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<h1 class="settitle" align="center">GNU libgomp</h1>







<a name="SEC_Overview"></a>
<h2 class="shortcontents-heading">Short Table of Contents</h2>

<div class="shortcontents">
<ul class="no-bullet">
<li><a name="stoc-Enabling-OpenMP-1" href="#toc-Enabling-OpenMP-1">1 Enabling OpenMP</a></li>
<li><a name="stoc-Runtime-Library-Routines-1" href="#toc-Runtime-Library-Routines-1">2 Runtime Library Routines</a></li>
<li><a name="stoc-Environment-Variables-1" href="#toc-Environment-Variables-1">3 Environment Variables</a></li>
<li><a name="stoc-Enabling-OpenACC-1" href="#toc-Enabling-OpenACC-1">4 Enabling OpenACC</a></li>
<li><a name="stoc-OpenACC-Runtime-Library-Routines-1" href="#toc-OpenACC-Runtime-Library-Routines-1">5 OpenACC Runtime Library Routines</a></li>
<li><a name="stoc-OpenACC-Environment-Variables-1" href="#toc-OpenACC-Environment-Variables-1">6 OpenACC Environment Variables</a></li>
<li><a name="stoc-CUDA-Streams-Usage-1" href="#toc-CUDA-Streams-Usage-1">7 CUDA Streams Usage</a></li>
<li><a name="stoc-OpenACC-Library-Interoperability-1" href="#toc-OpenACC-Library-Interoperability-1">8 OpenACC Library Interoperability</a></li>
<li><a name="stoc-The-libgomp-ABI-1" href="#toc-The-libgomp-ABI-1">9 The libgomp ABI</a></li>
<li><a name="stoc-Reporting-Bugs-1" href="#toc-Reporting-Bugs-1">10 Reporting Bugs</a></li>
<li><a name="stoc-GNU-General-Public-License" href="#toc-GNU-General-Public-License">GNU General Public License</a></li>
<li><a name="stoc-GNU-Free-Documentation-License-1" href="#toc-GNU-Free-Documentation-License-1">GNU Free Documentation License</a></li>
<li><a name="stoc-Funding-Free-Software" href="#toc-Funding-Free-Software">Funding Free Software</a></li>
<li><a name="stoc-Library-Index-1" href="#toc-Library-Index-1">Library Index</a></li>
</ul>
</div>

<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="no-bullet">
  <li><a name="toc-Enabling-OpenMP-1" href="#Enabling-OpenMP">1 Enabling OpenMP</a></li>
  <li><a name="toc-Runtime-Library-Routines-1" href="#Runtime-Library-Routines">2 Runtime Library Routines</a>
  <ul class="no-bullet">
    <li><a name="toc-omp_005fget_005factive_005flevel-_002d_002d-Number-of-parallel-regions" href="#omp_005fget_005factive_005flevel">2.1 <code>omp_get_active_level</code> &ndash; Number of parallel regions</a></li>
    <li><a name="toc-omp_005fget_005fancestor_005fthread_005fnum-_002d_002d-Ancestor-thread-ID" href="#omp_005fget_005fancestor_005fthread_005fnum">2.2 <code>omp_get_ancestor_thread_num</code> &ndash; Ancestor thread ID</a></li>
    <li><a name="toc-omp_005fget_005fcancellation-_002d_002d-Whether-cancellation-support-is-enabled" href="#omp_005fget_005fcancellation">2.3 <code>omp_get_cancellation</code> &ndash; Whether cancellation support is enabled</a></li>
    <li><a name="toc-omp_005fget_005fdefault_005fdevice-_002d_002d-Get-the-default-device-for-target-regions" href="#omp_005fget_005fdefault_005fdevice">2.4 <code>omp_get_default_device</code> &ndash; Get the default device for target regions</a></li>
    <li><a name="toc-omp_005fget_005fdynamic-_002d_002d-Dynamic-teams-setting" href="#omp_005fget_005fdynamic">2.5 <code>omp_get_dynamic</code> &ndash; Dynamic teams setting</a></li>
    <li><a name="toc-omp_005fget_005flevel-_002d_002d-Obtain-the-current-nesting-level" href="#omp_005fget_005flevel">2.6 <code>omp_get_level</code> &ndash; Obtain the current nesting level</a></li>
    <li><a name="toc-omp_005fget_005fmax_005factive_005flevels-_002d_002d-Maximum-number-of-active-regions" href="#omp_005fget_005fmax_005factive_005flevels">2.7 <code>omp_get_max_active_levels</code> &ndash; Maximum number of active regions</a></li>
    <li><a name="toc-omp_005fget_005fmax_005ftask_005fpriority-_002d_002d-Maximum-priority-value" href="#omp_005fget_005fmax_005ftask_005fpriority">2.8 <code>omp_get_max_task_priority</code> &ndash; Maximum priority value</a></li>
    <li><a name="toc-omp_005fget_005fmax_005fthreads-_002d_002d-Maximum-number-of-threads-of-parallel-region" href="#omp_005fget_005fmax_005fthreads">2.9 <code>omp_get_max_threads</code> &ndash; Maximum number of threads of parallel region</a></li>
    <li><a name="toc-omp_005fget_005fnested-_002d_002d-Nested-parallel-regions" href="#omp_005fget_005fnested">2.10 <code>omp_get_nested</code> &ndash; Nested parallel regions</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fdevices-_002d_002d-Number-of-target-devices" href="#omp_005fget_005fnum_005fdevices">2.11 <code>omp_get_num_devices</code> &ndash; Number of target devices</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fprocs-_002d_002d-Number-of-processors-online" href="#omp_005fget_005fnum_005fprocs">2.12 <code>omp_get_num_procs</code> &ndash; Number of processors online</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fteams-_002d_002d-Number-of-teams" href="#omp_005fget_005fnum_005fteams">2.13 <code>omp_get_num_teams</code> &ndash; Number of teams</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fthreads-_002d_002d-Size-of-the-active-team" href="#omp_005fget_005fnum_005fthreads">2.14 <code>omp_get_num_threads</code> &ndash; Size of the active team</a></li>
    <li><a name="toc-omp_005fget_005fproc_005fbind-_002d_002d-Whether-theads-may-be-moved-between-CPUs" href="#omp_005fget_005fproc_005fbind">2.15 <code>omp_get_proc_bind</code> &ndash; Whether theads may be moved between CPUs</a></li>
    <li><a name="toc-omp_005fget_005fschedule-_002d_002d-Obtain-the-runtime-scheduling-method" href="#omp_005fget_005fschedule">2.16 <code>omp_get_schedule</code> &ndash; Obtain the runtime scheduling method</a></li>
    <li><a name="toc-omp_005fget_005fteam_005fnum-_002d_002d-Get-team-number" href="#omp_005fget_005fteam_005fnum">2.17 <code>omp_get_team_num</code> &ndash; Get team number</a></li>
    <li><a name="toc-omp_005fget_005fteam_005fsize-_002d_002d-Number-of-threads-in-a-team" href="#omp_005fget_005fteam_005fsize">2.18 <code>omp_get_team_size</code> &ndash; Number of threads in a team</a></li>
    <li><a name="toc-omp_005fget_005fthread_005flimit-_002d_002d-Maximum-number-of-threads" href="#omp_005fget_005fthread_005flimit">2.19 <code>omp_get_thread_limit</code> &ndash; Maximum number of threads</a></li>
    <li><a name="toc-omp_005fget_005fthread_005fnum-_002d_002d-Current-thread-ID" href="#omp_005fget_005fthread_005fnum">2.20 <code>omp_get_thread_num</code> &ndash; Current thread ID</a></li>
    <li><a name="toc-omp_005fin_005fparallel-_002d_002d-Whether-a-parallel-region-is-active" href="#omp_005fin_005fparallel">2.21 <code>omp_in_parallel</code> &ndash; Whether a parallel region is active</a></li>
    <li><a name="toc-omp_005fin_005ffinal-_002d_002d-Whether-in-final-or-included-task-region" href="#omp_005fin_005ffinal">2.22 <code>omp_in_final</code> &ndash; Whether in final or included task region</a></li>
    <li><a name="toc-omp_005fis_005finitial_005fdevice-_002d_002d-Whether-executing-on-the-host-device" href="#omp_005fis_005finitial_005fdevice">2.23 <code>omp_is_initial_device</code> &ndash; Whether executing on the host device</a></li>
    <li><a name="toc-omp_005fset_005fdefault_005fdevice-_002d_002d-Set-the-default-device-for-target-regions" href="#omp_005fset_005fdefault_005fdevice">2.24 <code>omp_set_default_device</code> &ndash; Set the default device for target regions</a></li>
    <li><a name="toc-omp_005fset_005fdynamic-_002d_002d-Enable_002fdisable-dynamic-teams" href="#omp_005fset_005fdynamic">2.25 <code>omp_set_dynamic</code> &ndash; Enable/disable dynamic teams</a></li>
    <li><a name="toc-omp_005fset_005fmax_005factive_005flevels-_002d_002d-Limits-the-number-of-active-parallel-regions" href="#omp_005fset_005fmax_005factive_005flevels">2.26 <code>omp_set_max_active_levels</code> &ndash; Limits the number of active parallel regions</a></li>
    <li><a name="toc-omp_005fset_005fnested-_002d_002d-Enable_002fdisable-nested-parallel-regions" href="#omp_005fset_005fnested">2.27 <code>omp_set_nested</code> &ndash; Enable/disable nested parallel regions</a></li>
    <li><a name="toc-omp_005fset_005fnum_005fthreads-_002d_002d-Set-upper-team-size-limit" href="#omp_005fset_005fnum_005fthreads">2.28 <code>omp_set_num_threads</code> &ndash; Set upper team size limit</a></li>
    <li><a name="toc-omp_005fset_005fschedule-_002d_002d-Set-the-runtime-scheduling-method" href="#omp_005fset_005fschedule">2.29 <code>omp_set_schedule</code> &ndash; Set the runtime scheduling method</a></li>
    <li><a name="toc-omp_005finit_005flock-_002d_002d-Initialize-simple-lock" href="#omp_005finit_005flock">2.30 <code>omp_init_lock</code> &ndash; Initialize simple lock</a></li>
    <li><a name="toc-omp_005fset_005flock-_002d_002d-Wait-for-and-set-simple-lock" href="#omp_005fset_005flock">2.31 <code>omp_set_lock</code> &ndash; Wait for and set simple lock</a></li>
    <li><a name="toc-omp_005ftest_005flock-_002d_002d-Test-and-set-simple-lock-if-available" href="#omp_005ftest_005flock">2.32 <code>omp_test_lock</code> &ndash; Test and set simple lock if available</a></li>
    <li><a name="toc-omp_005funset_005flock-_002d_002d-Unset-simple-lock" href="#omp_005funset_005flock">2.33 <code>omp_unset_lock</code> &ndash; Unset simple lock</a></li>
    <li><a name="toc-omp_005fdestroy_005flock-_002d_002d-Destroy-simple-lock" href="#omp_005fdestroy_005flock">2.34 <code>omp_destroy_lock</code> &ndash; Destroy simple lock</a></li>
    <li><a name="toc-omp_005finit_005fnest_005flock-_002d_002d-Initialize-nested-lock" href="#omp_005finit_005fnest_005flock">2.35 <code>omp_init_nest_lock</code> &ndash; Initialize nested lock</a></li>
    <li><a name="toc-omp_005fset_005fnest_005flock-_002d_002d-Wait-for-and-set-nested-lock" href="#omp_005fset_005fnest_005flock">2.36 <code>omp_set_nest_lock</code> &ndash; Wait for and set nested lock</a></li>
    <li><a name="toc-omp_005ftest_005fnest_005flock-_002d_002d-Test-and-set-nested-lock-if-available" href="#omp_005ftest_005fnest_005flock">2.37 <code>omp_test_nest_lock</code> &ndash; Test and set nested lock if available</a></li>
    <li><a name="toc-omp_005funset_005fnest_005flock-_002d_002d-Unset-nested-lock" href="#omp_005funset_005fnest_005flock">2.38 <code>omp_unset_nest_lock</code> &ndash; Unset nested lock</a></li>
    <li><a name="toc-omp_005fdestroy_005fnest_005flock-_002d_002d-Destroy-nested-lock" href="#omp_005fdestroy_005fnest_005flock">2.39 <code>omp_destroy_nest_lock</code> &ndash; Destroy nested lock</a></li>
    <li><a name="toc-omp_005fget_005fwtick-_002d_002d-Get-timer-precision" href="#omp_005fget_005fwtick">2.40 <code>omp_get_wtick</code> &ndash; Get timer precision</a></li>
    <li><a name="toc-omp_005fget_005fwtime-_002d_002d-Elapsed-wall-clock-time" href="#omp_005fget_005fwtime">2.41 <code>omp_get_wtime</code> &ndash; Elapsed wall clock time</a></li>
  </ul></li>
  <li><a name="toc-Environment-Variables-1" href="#Environment-Variables">3 Environment Variables</a>
  <ul class="no-bullet">
    <li><a name="toc-OMP_005fCANCELLATION-_002d_002d-Set-whether-cancellation-is-activated" href="#OMP_005fCANCELLATION">3.1 <code>OMP_CANCELLATION</code> &ndash; Set whether cancellation is activated</a></li>
    <li><a name="toc-OMP_005fDISPLAY_005fENV-_002d_002d-Show-OpenMP-version-and-environment-variables" href="#OMP_005fDISPLAY_005fENV">3.2 <code>OMP_DISPLAY_ENV</code> &ndash; Show OpenMP version and environment variables</a></li>
    <li><a name="toc-OMP_005fDEFAULT_005fDEVICE-_002d_002d-Set-the-device-used-in-target-regions" href="#OMP_005fDEFAULT_005fDEVICE">3.3 <code>OMP_DEFAULT_DEVICE</code> &ndash; Set the device used in target regions</a></li>
    <li><a name="toc-OMP_005fDYNAMIC-_002d_002d-Dynamic-adjustment-of-threads" href="#OMP_005fDYNAMIC">3.4 <code>OMP_DYNAMIC</code> &ndash; Dynamic adjustment of threads</a></li>
    <li><a name="toc-OMP_005fMAX_005fACTIVE_005fLEVELS-_002d_002d-Set-the-maximum-number-of-nested-parallel-regions" href="#OMP_005fMAX_005fACTIVE_005fLEVELS">3.5 <code>OMP_MAX_ACTIVE_LEVELS</code> &ndash; Set the maximum number of nested parallel regions</a></li>
    <li><a name="toc-OMP_005fMAX_005fTASK_005fPRIORITY-_002d_002d-Set-the-maximum-priority" href="#OMP_005fMAX_005fTASK_005fPRIORITY">3.6 <code>OMP_MAX_TASK_PRIORITY</code> &ndash; Set the maximum priority</a></li>
    <li><a name="toc-OMP_005fNESTED-_002d_002d-Nested-parallel-regions" href="#OMP_005fNESTED">3.7 <code>OMP_NESTED</code> &ndash; Nested parallel regions</a></li>
    <li><a name="toc-OMP_005fNUM_005fTHREADS-_002d_002d-Specifies-the-number-of-threads-to-use" href="#OMP_005fNUM_005fTHREADS">3.8 <code>OMP_NUM_THREADS</code> &ndash; Specifies the number of threads to use</a></li>
    <li><a name="toc-OMP_005fPROC_005fBIND-_002d_002d-Whether-theads-may-be-moved-between-CPUs" href="#OMP_005fPROC_005fBIND">3.9 <code>OMP_PROC_BIND</code> &ndash; Whether theads may be moved between CPUs</a></li>
    <li><a name="toc-OMP_005fPLACES-_002d_002d-Specifies-on-which-CPUs-the-theads-should-be-placed" href="#OMP_005fPLACES">3.10 <code>OMP_PLACES</code> &ndash; Specifies on which CPUs the theads should be placed</a></li>
    <li><a name="toc-OMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size" href="#OMP_005fSTACKSIZE">3.11 <code>OMP_STACKSIZE</code> &ndash; Set default thread stack size</a></li>
    <li><a name="toc-OMP_005fSCHEDULE-_002d_002d-How-threads-are-scheduled" href="#OMP_005fSCHEDULE">3.12 <code>OMP_SCHEDULE</code> &ndash; How threads are scheduled</a></li>
    <li><a name="toc-OMP_005fTHREAD_005fLIMIT-_002d_002d-Set-the-maximum-number-of-threads" href="#OMP_005fTHREAD_005fLIMIT">3.13 <code>OMP_THREAD_LIMIT</code> &ndash; Set the maximum number of threads</a></li>
    <li><a name="toc-OMP_005fWAIT_005fPOLICY-_002d_002d-How-waiting-threads-are-handled" href="#OMP_005fWAIT_005fPOLICY">3.14 <code>OMP_WAIT_POLICY</code> &ndash; How waiting threads are handled</a></li>
    <li><a name="toc-GOMP_005fCPU_005fAFFINITY-_002d_002d-Bind-threads-to-specific-CPUs" href="#GOMP_005fCPU_005fAFFINITY">3.15 <code>GOMP_CPU_AFFINITY</code> &ndash; Bind threads to specific CPUs</a></li>
    <li><a name="toc-GOMP_005fDEBUG-_002d_002d-Enable-debugging-output" href="#GOMP_005fDEBUG">3.16 <code>GOMP_DEBUG</code> &ndash; Enable debugging output</a></li>
    <li><a name="toc-GOMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size" href="#GOMP_005fSTACKSIZE">3.17 <code>GOMP_STACKSIZE</code> &ndash; Set default thread stack size</a></li>
    <li><a name="toc-GOMP_005fSPINCOUNT-_002d_002d-Set-the-busy_002dwait-spin-count" href="#GOMP_005fSPINCOUNT">3.18 <code>GOMP_SPINCOUNT</code> &ndash; Set the busy-wait spin count</a></li>
    <li><a name="toc-GOMP_005fRTEMS_005fTHREAD_005fPOOLS-_002d_002d-Set-the-RTEMS-specific-thread-pools" href="#GOMP_005fRTEMS_005fTHREAD_005fPOOLS">3.19 <code>GOMP_RTEMS_THREAD_POOLS</code> &ndash; Set the RTEMS specific thread pools</a></li>
  </ul></li>
  <li><a name="toc-Enabling-OpenACC-1" href="#Enabling-OpenACC">4 Enabling OpenACC</a></li>
  <li><a name="toc-OpenACC-Runtime-Library-Routines-1" href="#OpenACC-Runtime-Library-Routines">5 OpenACC Runtime Library Routines</a>
  <ul class="no-bullet">
    <li><a name="toc-acc_005fget_005fnum_005fdevices-_002d_002d-Get-number-of-devices-for-given-device-type" href="#acc_005fget_005fnum_005fdevices">5.1 <code>acc_get_num_devices</code> &ndash; Get number of devices for given device type</a></li>
    <li><a name="toc-acc_005fset_005fdevice_005ftype-_002d_002d-Set-type-of-device-accelerator-to-use_002e" href="#acc_005fset_005fdevice_005ftype">5.2 <code>acc_set_device_type</code> &ndash; Set type of device accelerator to use.</a></li>
    <li><a name="toc-acc_005fget_005fdevice_005ftype-_002d_002d-Get-type-of-device-accelerator-to-be-used_002e" href="#acc_005fget_005fdevice_005ftype">5.3 <code>acc_get_device_type</code> &ndash; Get type of device accelerator to be used.</a></li>
    <li><a name="toc-acc_005fset_005fdevice_005fnum-_002d_002d-Set-device-number-to-use_002e" href="#acc_005fset_005fdevice_005fnum">5.4 <code>acc_set_device_num</code> &ndash; Set device number to use.</a></li>
    <li><a name="toc-acc_005fget_005fdevice_005fnum-_002d_002d-Get-device-number-to-be-used_002e" href="#acc_005fget_005fdevice_005fnum">5.5 <code>acc_get_device_num</code> &ndash; Get device number to be used.</a></li>
    <li><a name="toc-acc_005fasync_005ftest-_002d_002d-Test-for-completion-of-a-specific-asynchronous-operation_002e" href="#acc_005fasync_005ftest">5.6 <code>acc_async_test</code> &ndash; Test for completion of a specific asynchronous operation.</a></li>
    <li><a name="toc-acc_005fasync_005ftest_005fall-_002d_002d-Tests-for-completion-of-all-asynchronous-operations_002e" href="#acc_005fasync_005ftest_005fall">5.7 <code>acc_async_test_all</code> &ndash; Tests for completion of all asynchronous operations.</a></li>
    <li><a name="toc-acc_005fwait-_002d_002d-Wait-for-completion-of-a-specific-asynchronous-operation_002e" href="#acc_005fwait">5.8 <code>acc_wait</code> &ndash; Wait for completion of a specific asynchronous operation.</a></li>
    <li><a name="toc-acc_005fwait_005fall-_002d_002d-Waits-for-completion-of-all-asynchronous-operations_002e" href="#acc_005fwait_005fall">5.9 <code>acc_wait_all</code> &ndash; Waits for completion of all asynchronous operations.</a></li>
    <li><a name="toc-acc_005fwait_005fall_005fasync-_002d_002d-Wait-for-completion-of-all-asynchronous-operations_002e" href="#acc_005fwait_005fall_005fasync">5.10 <code>acc_wait_all_async</code> &ndash; Wait for completion of all asynchronous operations.</a></li>
    <li><a name="toc-acc_005fwait_005fasync-_002d_002d-Wait-for-completion-of-asynchronous-operations_002e" href="#acc_005fwait_005fasync">5.11 <code>acc_wait_async</code> &ndash; Wait for completion of asynchronous operations.</a></li>
    <li><a name="toc-acc_005finit-_002d_002d-Initialize-runtime-for-a-specific-device-type_002e" href="#acc_005finit">5.12 <code>acc_init</code> &ndash; Initialize runtime for a specific device type.</a></li>
    <li><a name="toc-acc_005fshutdown-_002d_002d-Shuts-down-the-runtime-for-a-specific-device-type_002e" href="#acc_005fshutdown">5.13 <code>acc_shutdown</code> &ndash; Shuts down the runtime for a specific device type.</a></li>
    <li><a name="toc-acc_005fon_005fdevice-_002d_002d-Whether-executing-on-a-particular-device" href="#acc_005fon_005fdevice">5.14 <code>acc_on_device</code> &ndash; Whether executing on a particular device</a></li>
    <li><a name="toc-acc_005fmalloc-_002d_002d-Allocate-device-memory_002e" href="#acc_005fmalloc">5.15 <code>acc_malloc</code> &ndash; Allocate device memory.</a></li>
    <li><a name="toc-acc_005ffree-_002d_002d-Free-device-memory_002e" href="#acc_005ffree">5.16 <code>acc_free</code> &ndash; Free device memory.</a></li>
    <li><a name="toc-acc_005fcopyin-_002d_002d-Allocate-device-memory-and-copy-host-memory-to-it_002e" href="#acc_005fcopyin">5.17 <code>acc_copyin</code> &ndash; Allocate device memory and copy host memory to it.</a></li>
    <li><a name="toc-acc_005fpresent_005for_005fcopyin-_002d_002d-If-the-data-is-not-present-on-the-device_002c-allocate-device-memory-and-copy-from-host-memory_002e" href="#acc_005fpresent_005for_005fcopyin">5.18 <code>acc_present_or_copyin</code> &ndash; If the data is not present on the device, allocate device memory and copy from host memory.</a></li>
    <li><a name="toc-acc_005fcreate-_002d_002d-Allocate-device-memory-and-map-it-to-host-memory_002e" href="#acc_005fcreate">5.19 <code>acc_create</code> &ndash; Allocate device memory and map it to host memory.</a></li>
    <li><a name="toc-acc_005fpresent_005for_005fcreate-_002d_002d-If-the-data-is-not-present-on-the-device_002c-allocate-device-memory-and-map-it-to-host-memory_002e" href="#acc_005fpresent_005for_005fcreate">5.20 <code>acc_present_or_create</code> &ndash; If the data is not present on the device, allocate device memory and map it to host memory.</a></li>
    <li><a name="toc-acc_005fcopyout-_002d_002d-Copy-device-memory-to-host-memory_002e" href="#acc_005fcopyout">5.21 <code>acc_copyout</code> &ndash; Copy device memory to host memory.</a></li>
    <li><a name="toc-acc_005fdelete-_002d_002d-Free-device-memory_002e" href="#acc_005fdelete">5.22 <code>acc_delete</code> &ndash; Free device memory.</a></li>
    <li><a name="toc-acc_005fupdate_005fdevice-_002d_002d-Update-device-memory-from-mapped-host-memory_002e" href="#acc_005fupdate_005fdevice">5.23 <code>acc_update_device</code> &ndash; Update device memory from mapped host memory.</a></li>
    <li><a name="toc-acc_005fupdate_005fself-_002d_002d-Update-host-memory-from-mapped-device-memory_002e" href="#acc_005fupdate_005fself">5.24 <code>acc_update_self</code> &ndash; Update host memory from mapped device memory.</a></li>
    <li><a name="toc-acc_005fmap_005fdata-_002d_002d-Map-previously-allocated-device-memory-to-host-memory_002e" href="#acc_005fmap_005fdata">5.25 <code>acc_map_data</code> &ndash; Map previously allocated device memory to host memory.</a></li>
    <li><a name="toc-acc_005funmap_005fdata-_002d_002d-Unmap-device-memory-from-host-memory_002e" href="#acc_005funmap_005fdata">5.26 <code>acc_unmap_data</code> &ndash; Unmap device memory from host memory.</a></li>
    <li><a name="toc-acc_005fdeviceptr-_002d_002d-Get-device-pointer-associated-with-specific-host-address_002e" href="#acc_005fdeviceptr">5.27 <code>acc_deviceptr</code> &ndash; Get device pointer associated with specific host address.</a></li>
    <li><a name="toc-acc_005fhostptr-_002d_002d-Get-host-pointer-associated-with-specific-device-address_002e" href="#acc_005fhostptr">5.28 <code>acc_hostptr</code> &ndash; Get host pointer associated with specific device address.</a></li>
    <li><a name="toc-acc_005fis_005fpresent-_002d_002d-Indicate-whether-host-variable-_002f-array-is-present-on-device_002e" href="#acc_005fis_005fpresent">5.29 <code>acc_is_present</code> &ndash; Indicate whether host variable / array is present on device.</a></li>
    <li><a name="toc-acc_005fmemcpy_005fto_005fdevice-_002d_002d-Copy-host-memory-to-device-memory_002e" href="#acc_005fmemcpy_005fto_005fdevice">5.30 <code>acc_memcpy_to_device</code> &ndash; Copy host memory to device memory.</a></li>
    <li><a name="toc-acc_005fmemcpy_005ffrom_005fdevice-_002d_002d-Copy-device-memory-to-host-memory_002e" href="#acc_005fmemcpy_005ffrom_005fdevice">5.31 <code>acc_memcpy_from_device</code> &ndash; Copy device memory to host memory.</a></li>
    <li><a name="toc-acc_005fget_005fcurrent_005fcuda_005fdevice-_002d_002d-Get-CUDA-device-handle_002e" href="#acc_005fget_005fcurrent_005fcuda_005fdevice">5.32 <code>acc_get_current_cuda_device</code> &ndash; Get CUDA device handle.</a></li>
    <li><a name="toc-acc_005fget_005fcurrent_005fcuda_005fcontext-_002d_002d-Get-CUDA-context-handle_002e" href="#acc_005fget_005fcurrent_005fcuda_005fcontext">5.33 <code>acc_get_current_cuda_context</code> &ndash; Get CUDA context handle.</a></li>
    <li><a name="toc-acc_005fget_005fcuda_005fstream-_002d_002d-Get-CUDA-stream-handle_002e" href="#acc_005fget_005fcuda_005fstream">5.34 <code>acc_get_cuda_stream</code> &ndash; Get CUDA stream handle.</a></li>
    <li><a name="toc-acc_005fset_005fcuda_005fstream-_002d_002d-Set-CUDA-stream-handle_002e" href="#acc_005fset_005fcuda_005fstream">5.35 <code>acc_set_cuda_stream</code> &ndash; Set CUDA stream handle.</a></li>
  </ul></li>
  <li><a name="toc-OpenACC-Environment-Variables-1" href="#OpenACC-Environment-Variables">6 OpenACC Environment Variables</a>
  <ul class="no-bullet">
    <li><a name="toc-ACC_005fDEVICE_005fTYPE-1" href="#ACC_005fDEVICE_005fTYPE">6.1 <code>ACC_DEVICE_TYPE</code></a></li>
    <li><a name="toc-ACC_005fDEVICE_005fNUM-1" href="#ACC_005fDEVICE_005fNUM">6.2 <code>ACC_DEVICE_NUM</code></a></li>
    <li><a name="toc-GCC_005fACC_005fNOTIFY-1" href="#GCC_005fACC_005fNOTIFY">6.3 <code>GCC_ACC_NOTIFY</code></a></li>
  </ul></li>
  <li><a name="toc-CUDA-Streams-Usage-1" href="#CUDA-Streams-Usage">7 CUDA Streams Usage</a></li>
  <li><a name="toc-OpenACC-Library-Interoperability-1" href="#OpenACC-Library-Interoperability">8 OpenACC Library Interoperability</a>
  <ul class="no-bullet">
    <li><a name="toc-Introduction-1" href="#Introduction-1">8.1 Introduction</a></li>
    <li><a name="toc-First-invocation_003a-NVIDIA-CUBLAS-library-API" href="#First-invocation_003a-NVIDIA-CUBLAS-library-API">8.2 First invocation: NVIDIA CUBLAS library API</a></li>
    <li><a name="toc-First-invocation_003a-OpenACC-library-API" href="#First-invocation_003a-OpenACC-library-API">8.3 First invocation: OpenACC library API</a></li>
    <li><a name="toc-OpenACC-library-and-environment-variables" href="#OpenACC-library-and-environment-variables">8.4 OpenACC library and environment variables</a></li>
  </ul></li>
  <li><a name="toc-The-libgomp-ABI-1" href="#The-libgomp-ABI">9 The libgomp ABI</a>
  <ul class="no-bullet">
    <li><a name="toc-Implementing-MASTER-construct-1" href="#Implementing-MASTER-construct">9.1 Implementing MASTER construct</a></li>
    <li><a name="toc-Implementing-CRITICAL-construct-1" href="#Implementing-CRITICAL-construct">9.2 Implementing CRITICAL construct</a></li>
    <li><a name="toc-Implementing-ATOMIC-construct-1" href="#Implementing-ATOMIC-construct">9.3 Implementing ATOMIC construct</a></li>
    <li><a name="toc-Implementing-FLUSH-construct-1" href="#Implementing-FLUSH-construct">9.4 Implementing FLUSH construct</a></li>
    <li><a name="toc-Implementing-BARRIER-construct-1" href="#Implementing-BARRIER-construct">9.5 Implementing BARRIER construct</a></li>
    <li><a name="toc-Implementing-THREADPRIVATE-construct-1" href="#Implementing-THREADPRIVATE-construct">9.6 Implementing THREADPRIVATE construct</a></li>
    <li><a name="toc-Implementing-PRIVATE-clause-1" href="#Implementing-PRIVATE-clause">9.7 Implementing PRIVATE clause</a></li>
    <li><a name="toc-Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1" href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses">9.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a></li>
    <li><a name="toc-Implementing-REDUCTION-clause-1" href="#Implementing-REDUCTION-clause">9.9 Implementing REDUCTION clause</a></li>
    <li><a name="toc-Implementing-PARALLEL-construct-1" href="#Implementing-PARALLEL-construct">9.10 Implementing PARALLEL construct</a></li>
    <li><a name="toc-Implementing-FOR-construct-1" href="#Implementing-FOR-construct">9.11 Implementing FOR construct</a></li>
    <li><a name="toc-Implementing-ORDERED-construct-1" href="#Implementing-ORDERED-construct">9.12 Implementing ORDERED construct</a></li>
    <li><a name="toc-Implementing-SECTIONS-construct-1" href="#Implementing-SECTIONS-construct">9.13 Implementing SECTIONS construct</a></li>
    <li><a name="toc-Implementing-SINGLE-construct-1" href="#Implementing-SINGLE-construct">9.14 Implementing SINGLE construct</a></li>
    <li><a name="toc-Implementing-OpenACC_0027s-PARALLEL-construct-1" href="#Implementing-OpenACC_0027s-PARALLEL-construct">9.15 Implementing OpenACC&rsquo;s PARALLEL construct</a></li>
  </ul></li>
  <li><a name="toc-Reporting-Bugs-1" href="#Reporting-Bugs">10 Reporting Bugs</a></li>
  <li><a name="toc-GNU-General-Public-License" href="#Copying">GNU General Public License</a></li>
  <li><a name="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">GNU Free Documentation License</a>
  <ul class="no-bullet">
    <li><a name="toc-ADDENDUM_003a-How-to-use-this-License-for-your-documents" href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</a></li>
  </ul></li>
  <li><a name="toc-Funding-Free-Software" href="#Funding">Funding Free Software</a></li>
  <li><a name="toc-Library-Index-1" href="#Library-Index">Library Index</a></li>
</ul>
</div>



<a name="Top"></a>
<div class="header">
<p>
Next: <a href="#Enabling-OpenMP" accesskey="n" rel="next">Enabling OpenMP</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Introduction"></a>
<h1 class="top">Introduction</h1>
<a name="index-Introduction"></a>

<p>This manual documents the usage of libgomp, the GNU Offloading and
Multi Processing Runtime Library.  This includes the GNU
implementation of the <a href="http://www.openmp.org">OpenMP</a> Application
Programming Interface (API) for multi-platform shared-memory parallel
programming in C/C++ and Fortran, and the GNU implementation of the
<a href="https://www.openacc.org">OpenACC</a> Application Programming
Interface (API) for offloading of code to accelerator devices in C/C++
and Fortran.
</p>
<p>Originally, libgomp implemented the GNU OpenMP Runtime Library.  Based
on this, support for OpenACC and offloading (both OpenACC and OpenMP
4&rsquo;s target construct) has been added later on, and the library&rsquo;s name
changed to GNU Offloading and Multi Processing Runtime Library.
</p>


<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Enabling-OpenMP" accesskey="1">Enabling OpenMP</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to enable OpenMP for your applications.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Runtime-Library-Routines" accesskey="2">Runtime Library Routines</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">The OpenMP runtime application programming 
                               interface.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Environment-Variables" accesskey="3">Environment Variables</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Influencing runtime behavior with environment 
                               variables.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Enabling-OpenACC" accesskey="4">Enabling OpenACC</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to enable OpenACC for your
                               applications.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OpenACC-Runtime-Library-Routines" accesskey="5">OpenACC Runtime Library Routines</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">The OpenACC runtime application
                               programming interface.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OpenACC-Environment-Variables" accesskey="6">OpenACC Environment Variables</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Influencing OpenACC runtime behavior with
                               environment variables.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#CUDA-Streams-Usage" accesskey="7">CUDA Streams Usage</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Notes on the implementation of
                               asynchronous operations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OpenACC-Library-Interoperability" accesskey="8">OpenACC Library Interoperability</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">OpenACC library interoperability with the
                               NVIDIA CUBLAS library.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-libgomp-ABI" accesskey="9">The libgomp ABI</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Notes on the external ABI presented by libgomp.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Reporting-Bugs">Reporting Bugs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to report bugs in the GNU Offloading and
                               Multi Processing Runtime Library.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Copying">Copying</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">GNU general public license says
                               how you can copy and share libgomp.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
                               How you can copy and share this manual.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Funding">Funding</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to help assure continued work for free 
                               software.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Library-Index">Library Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Index of this documentation.
</td></tr>
</table>



<hr>
<a name="Enabling-OpenMP"></a>
<div class="header">
<p>
Next: <a href="#Runtime-Library-Routines" accesskey="n" rel="next">Runtime Library Routines</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Enabling-OpenMP-1"></a>
<h2 class="chapter">1 Enabling OpenMP</h2>

<p>To activate the OpenMP extensions for C/C++ and Fortran, the compile-time 
flag <code>-fopenmp</code> must be specified.  This enables the OpenMP directive
<code>#pragma omp</code> in C/C++ and <code>!$omp</code> directives in free form, 
<code>c$omp</code>, <code>*$omp</code> and <code>!$omp</code> directives in fixed form, 
<code>!$</code> conditional compilation sentinels in free form and <code>c$</code>,
<code>*$</code> and <code>!$</code> sentinels in fixed form, for Fortran.  The flag also
arranges for automatic linking of the OpenMP runtime library 
(<a href="#Runtime-Library-Routines">Runtime Library Routines</a>).
</p>
<p>A complete description of all OpenMP directives accepted may be found in 
the <a href="http://www.openmp.org">OpenMP Application Program Interface</a> manual,
version 4.5.
</p>


<hr>
<a name="Runtime-Library-Routines"></a>
<div class="header">
<p>
Next: <a href="#Environment-Variables" accesskey="n" rel="next">Environment Variables</a>, Previous: <a href="#Enabling-OpenMP" accesskey="p" rel="prev">Enabling OpenMP</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Runtime-Library-Routines-1"></a>
<h2 class="chapter">2 Runtime Library Routines</h2>

<p>The runtime routines described here are defined by Section 3 of the OpenMP
specification in version 4.5.  The routines are structured in following
three parts:
</p>
<table class="menu" border="0" cellspacing="0">
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">Control threads, processors and the parallel environment.  They have C
linkage, and do not throw exceptions.

</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005factive_005flevel" accesskey="1">omp_get_active_level</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of active parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="2">omp_get_ancestor_thread_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Ancestor thread ID
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fcancellation" accesskey="3">omp_get_cancellation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether cancellation support is enabled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fdefault_005fdevice" accesskey="4">omp_get_default_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get the default device for target regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fdynamic" accesskey="5">omp_get_dynamic</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Dynamic teams setting
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005flevel" accesskey="6">omp_get_level</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="7">omp_get_max_active_levels</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of active regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fmax_005ftask_005fpriority" accesskey="8">omp_get_max_task_priority</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum task priority value that can be set
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fmax_005fthreads" accesskey="9">omp_get_max_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of threads of parallel region
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnested">omp_get_nested</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fdevices">omp_get_num_devices</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of target devices
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fprocs">omp_get_num_procs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of processors online
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fteams">omp_get_num_teams</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of teams
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Size of the active team
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fproc_005fbind">omp_get_proc_bind</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether theads may be moved between CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fschedule">omp_get_schedule</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Obtain the runtime scheduling method
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fteam_005fnum">omp_get_team_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get team number
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fteam_005fsize">omp_get_team_size</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of threads in a team
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fthread_005fnum">omp_get_thread_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Current thread ID
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fin_005fparallel">omp_in_parallel</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether a parallel region is active
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fin_005ffinal">omp_in_final</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether in final or included task region
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fis_005finitial_005fdevice">omp_is_initial_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether executing on the host device
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fdefault_005fdevice">omp_set_default_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the default device for target regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable/disable dynamic teams
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Limits the number of active parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnested">omp_set_nested</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable/disable nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set upper team size limit
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fschedule">omp_set_schedule</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the runtime scheduling method
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">

Initialize, set, test, unset and destroy simple and nested locks.

</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="#omp_005finit_005flock">omp_init_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Initialize simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005flock">omp_set_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for and set simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005ftest_005flock">omp_test_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Test and set simple lock if available
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005funset_005flock">omp_unset_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Unset simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fdestroy_005flock">omp_destroy_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Destroy simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005finit_005fnest_005flock">omp_init_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Initialize nested lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnest_005flock">omp_set_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for and set simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005ftest_005fnest_005flock">omp_test_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Test and set nested lock if available
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005funset_005fnest_005flock">omp_unset_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Unset nested lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fdestroy_005fnest_005flock">omp_destroy_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Destroy nested lock
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">

Portable, thread-based, wall clock timer.

</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fwtick">omp_get_wtick</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get timer precision.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fwtime">omp_get_wtime</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Elapsed wall clock time.
</td></tr>
</table>



<hr>
<a name="omp_005fget_005factive_005flevel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="n" rel="next">omp_get_ancestor_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005factive_005flevel-_002d_002d-Number-of-parallel-regions"></a>
<h3 class="section">2.1 <code>omp_get_active_level</code> &ndash; Number of parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the nesting level for the active parallel blocks,
which enclose the calling call.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_active_level(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_active_level()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fmax_005factive_005flevels">omp_get_max_active_levels</a>, <a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.20.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fancestor_005fthread_005fnum"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fcancellation" accesskey="n" rel="next">omp_get_cancellation</a>, Previous: <a href="#omp_005fget_005factive_005flevel" accesskey="p" rel="prev">omp_get_active_level</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fancestor_005fthread_005fnum-_002d_002d-Ancestor-thread-ID"></a>
<h3 class="section">2.2 <code>omp_get_ancestor_thread_num</code> &ndash; Ancestor thread ID</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the thread identification number for the given
nesting level of the current thread.  For values of <var>level</var> outside
zero to <code>omp_get_level</code> -1 is returned; if <var>level</var> is
<code>omp_get_level</code> the result is identical to <code>omp_get_thread_num</code>.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_ancestor_thread_num(int level);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_ancestor_thread_num(level)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer level</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fthread_005fnum">omp_get_thread_num</a>, <a href="#omp_005fget_005fteam_005fsize">omp_get_team_size</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.18.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fcancellation"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fdefault_005fdevice" accesskey="n" rel="next">omp_get_default_device</a>, Previous: <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="p" rel="prev">omp_get_ancestor_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fcancellation-_002d_002d-Whether-cancellation-support-is-enabled"></a>
<h3 class="section">2.3 <code>omp_get_cancellation</code> &ndash; Whether cancellation support is enabled</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if cancellation is activated, <code>false</code>
otherwise.  Here, <code>true</code> and <code>false</code> represent their language-specific
counterparts.  Unless <code>OMP_CANCELLATION</code> is set true, cancellations are
deactivated.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_cancellation(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_get_cancellation()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fCANCELLATION">OMP_CANCELLATION</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.9.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fdefault_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fdynamic" accesskey="n" rel="next">omp_get_dynamic</a>, Previous: <a href="#omp_005fget_005fcancellation" accesskey="p" rel="prev">omp_get_cancellation</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fdefault_005fdevice-_002d_002d-Get-the-default-device-for-target-regions"></a>
<h3 class="section">2.4 <code>omp_get_default_device</code> &ndash; Get the default device for target regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Get the default device for target regions without device clause.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_default_device(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_default_device()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fDEFAULT_005fDEVICE">OMP_DEFAULT_DEVICE</a>, <a href="#omp_005fset_005fdefault_005fdevice">omp_set_default_device</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.30.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fdynamic"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005flevel" accesskey="n" rel="next">omp_get_level</a>, Previous: <a href="#omp_005fget_005fdefault_005fdevice" accesskey="p" rel="prev">omp_get_default_device</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fdynamic-_002d_002d-Dynamic-teams-setting"></a>
<h3 class="section">2.5 <code>omp_get_dynamic</code> &ndash; Dynamic teams setting</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if enabled, <code>false</code> otherwise. 
Here, <code>true</code> and <code>false</code> represent their language-specific 
counterparts.
</p>
<p>The dynamic team setting may be initialized at startup by the 
<code>OMP_DYNAMIC</code> environment variable or at runtime using
<code>omp_set_dynamic</code>.  If undefined, dynamic adjustment is
disabled by default.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_dynamic(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_get_dynamic()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>, <a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.8.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005flevel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="n" rel="next">omp_get_max_active_levels</a>, Previous: <a href="#omp_005fget_005fdynamic" accesskey="p" rel="prev">omp_get_dynamic</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005flevel-_002d_002d-Obtain-the-current-nesting-level"></a>
<h3 class="section">2.6 <code>omp_get_level</code> &ndash; Obtain the current nesting level</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the nesting level for the parallel blocks,
which enclose the calling call.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_level(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_level()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.17.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fmax_005factive_005flevels"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fmax_005ftask_005fpriority" accesskey="n" rel="next">omp_get_max_task_priority</a>, Previous: <a href="#omp_005fget_005flevel" accesskey="p" rel="prev">omp_get_level</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fmax_005factive_005flevels-_002d_002d-Maximum-number-of-active-regions"></a>
<h3 class="section">2.7 <code>omp_get_max_active_levels</code> &ndash; Maximum number of active regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function obtains the maximum allowed number of nested, active parallel regions.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_max_active_levels(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_max_active_levels()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>, <a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.16.
</p></dd>
</dl>


<hr>
<a name="omp_005fget_005fmax_005ftask_005fpriority"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fmax_005fthreads" accesskey="n" rel="next">omp_get_max_threads</a>, Previous: <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="p" rel="prev">omp_get_max_active_levels</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fmax_005ftask_005fpriority-_002d_002d-Maximum-priority-value"></a>
<h3 class="section">2.8 <code>omp_get_max_task_priority</code> &ndash; Maximum priority value</h3>
<p>that can be set for tasks.
</p><dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function obtains the maximum allowed priority number for tasks.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_max_task_priority(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_max_task_priority()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.29.
</p></dd>
</dl>


<hr>
<a name="omp_005fget_005fmax_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnested" accesskey="n" rel="next">omp_get_nested</a>, Previous: <a href="#omp_005fget_005fmax_005ftask_005fpriority" accesskey="p" rel="prev">omp_get_max_task_priority</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fmax_005fthreads-_002d_002d-Maximum-number-of-threads-of-parallel-region"></a>
<h3 class="section">2.9 <code>omp_get_max_threads</code> &ndash; Maximum number of threads of parallel region</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Return the maximum number of threads used for the current parallel region
that does not use the clause <code>num_threads</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_max_threads(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_max_threads()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>, <a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>, <a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.3.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnested"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fdevices" accesskey="n" rel="next">omp_get_num_devices</a>, Previous: <a href="#omp_005fget_005fmax_005fthreads" accesskey="p" rel="prev">omp_get_max_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnested-_002d_002d-Nested-parallel-regions"></a>
<h3 class="section">2.10 <code>omp_get_nested</code> &ndash; Nested parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if nested parallel regions are
enabled, <code>false</code> otherwise.  Here, <code>true</code> and <code>false</code>
represent their language-specific counterparts.
</p>
<p>Nested parallel regions may be initialized at startup by the 
<code>OMP_NESTED</code> environment variable or at runtime using
<code>omp_set_nested</code>.  If undefined, nested parallel regions are
disabled by default.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_nested(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_get_nested()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnested">omp_set_nested</a>, <a href="#OMP_005fNESTED">OMP_NESTED</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.11.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fdevices"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fprocs" accesskey="n" rel="next">omp_get_num_procs</a>, Previous: <a href="#omp_005fget_005fnested" accesskey="p" rel="prev">omp_get_nested</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fdevices-_002d_002d-Number-of-target-devices"></a>
<h3 class="section">2.11 <code>omp_get_num_devices</code> &ndash; Number of target devices</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of target devices.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_devices(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_devices()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.31.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fprocs"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fteams" accesskey="n" rel="next">omp_get_num_teams</a>, Previous: <a href="#omp_005fget_005fnum_005fdevices" accesskey="p" rel="prev">omp_get_num_devices</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fprocs-_002d_002d-Number-of-processors-online"></a>
<h3 class="section">2.12 <code>omp_get_num_procs</code> &ndash; Number of processors online</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of processors online on that device.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_procs(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_procs()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.5.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fteams"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fthreads" accesskey="n" rel="next">omp_get_num_threads</a>, Previous: <a href="#omp_005fget_005fnum_005fprocs" accesskey="p" rel="prev">omp_get_num_procs</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fteams-_002d_002d-Number-of-teams"></a>
<h3 class="section">2.13 <code>omp_get_num_teams</code> &ndash; Number of teams</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of teams in the current team region.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_teams(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_teams()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.32.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fproc_005fbind" accesskey="n" rel="next">omp_get_proc_bind</a>, Previous: <a href="#omp_005fget_005fnum_005fteams" accesskey="p" rel="prev">omp_get_num_teams</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fthreads-_002d_002d-Size-of-the-active-team"></a>
<h3 class="section">2.14 <code>omp_get_num_threads</code> &ndash; Size of the active team</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of threads in the current team.  In a sequential section of
the program <code>omp_get_num_threads</code> returns 1.
</p>
<p>The default team size may be initialized at startup by the 
<code>OMP_NUM_THREADS</code> environment variable.  At runtime, the size
of the current team may be set either by the <code>NUM_THREADS</code>
clause or by <code>omp_set_num_threads</code>.  If none of the above were
used to define a specific value and <code>OMP_DYNAMIC</code> is disabled,
one thread per CPU online is used.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_threads(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_threads()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>, <a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>, <a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.2.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fproc_005fbind"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fschedule" accesskey="n" rel="next">omp_get_schedule</a>, Previous: <a href="#omp_005fget_005fnum_005fthreads" accesskey="p" rel="prev">omp_get_num_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fproc_005fbind-_002d_002d-Whether-theads-may-be-moved-between-CPUs"></a>
<h3 class="section">2.15 <code>omp_get_proc_bind</code> &ndash; Whether theads may be moved between CPUs</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This functions returns the currently active thread affinity policy, which is
set via <code>OMP_PROC_BIND</code>.  Possible values are <code>omp_proc_bind_false</code>,
<code>omp_proc_bind_true</code>, <code>omp_proc_bind_master</code>,
<code>omp_proc_bind_close</code> and <code>omp_proc_bind_spread</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>omp_proc_bind_t omp_get_proc_bind(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer(kind=omp_proc_bind_kind) function omp_get_proc_bind()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a>, <a href="#OMP_005fPLACES">OMP_PLACES</a>, <a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>,
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.22.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fschedule"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fteam_005fnum" accesskey="n" rel="next">omp_get_team_num</a>, Previous: <a href="#omp_005fget_005fproc_005fbind" accesskey="p" rel="prev">omp_get_proc_bind</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fschedule-_002d_002d-Obtain-the-runtime-scheduling-method"></a>
<h3 class="section">2.16 <code>omp_get_schedule</code> &ndash; Obtain the runtime scheduling method</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Obtain the runtime scheduling method.  The <var>kind</var> argument will be
set to the value <code>omp_sched_static</code>, <code>omp_sched_dynamic</code>,
<code>omp_sched_guided</code> or <code>omp_sched_auto</code>.  The second argument,
<var>chunk_size</var>, is set to the chunk size.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_get_schedule(omp_sched_t *kind, int *chunk_size);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_get_schedule(kind, chunk_size)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=omp_sched_kind) kind</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer chunk_size</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fschedule">omp_set_schedule</a>, <a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.13.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fteam_005fnum"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fteam_005fsize" accesskey="n" rel="next">omp_get_team_size</a>, Previous: <a href="#omp_005fget_005fschedule" accesskey="p" rel="prev">omp_get_schedule</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fteam_005fnum-_002d_002d-Get-team-number"></a>
<h3 class="section">2.17 <code>omp_get_team_num</code> &ndash; Get team number</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the team number of the calling thread.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_team_num(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_team_num()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.33.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fteam_005fsize"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fthread_005flimit" accesskey="n" rel="next">omp_get_thread_limit</a>, Previous: <a href="#omp_005fget_005fteam_005fnum" accesskey="p" rel="prev">omp_get_team_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fteam_005fsize-_002d_002d-Number-of-threads-in-a-team"></a>
<h3 class="section">2.18 <code>omp_get_team_size</code> &ndash; Number of threads in a team</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the number of threads in a thread team to which
either the current thread or its ancestor belongs.  For values of <var>level</var>
outside zero to <code>omp_get_level</code>, -1 is returned; if <var>level</var> is zero,
1 is returned, and for <code>omp_get_level</code>, the result is identical
to <code>omp_get_num_threads</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_team_size(int level);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_team_size(level)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer level</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fancestor_005fthread_005fnum">omp_get_ancestor_thread_num</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.19.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fthread_005flimit"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fthread_005fnum" accesskey="n" rel="next">omp_get_thread_num</a>, Previous: <a href="#omp_005fget_005fteam_005fsize" accesskey="p" rel="prev">omp_get_team_size</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fthread_005flimit-_002d_002d-Maximum-number-of-threads"></a>
<h3 class="section">2.19 <code>omp_get_thread_limit</code> &ndash; Maximum number of threads</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Return the maximum number of threads of the program.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_thread_limit(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_thread_limit()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>, <a href="#OMP_005fTHREAD_005fLIMIT">OMP_THREAD_LIMIT</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.14.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fthread_005fnum"></a>
<div class="header">
<p>
Next: <a href="#omp_005fin_005fparallel" accesskey="n" rel="next">omp_in_parallel</a>, Previous: <a href="#omp_005fget_005fthread_005flimit" accesskey="p" rel="prev">omp_get_thread_limit</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fthread_005fnum-_002d_002d-Current-thread-ID"></a>
<h3 class="section">2.20 <code>omp_get_thread_num</code> &ndash; Current thread ID</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns a unique thread identification number within the current team.
In a sequential parts of the program, <code>omp_get_thread_num</code>
always returns 0.  In parallel regions the return value varies
from 0 to <code>omp_get_num_threads</code>-1 inclusive.  The return
value of the master thread of a team is always 0.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_thread_num(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_thread_num()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005fancestor_005fthread_005fnum">omp_get_ancestor_thread_num</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.4.
</p></dd>
</dl>



<hr>
<a name="omp_005fin_005fparallel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fin_005ffinal" accesskey="n" rel="next">omp_in_final</a>, Previous: <a href="#omp_005fget_005fthread_005fnum" accesskey="p" rel="prev">omp_get_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fin_005fparallel-_002d_002d-Whether-a-parallel-region-is-active"></a>
<h3 class="section">2.21 <code>omp_in_parallel</code> &ndash; Whether a parallel region is active</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if currently running in parallel,
<code>false</code> otherwise.  Here, <code>true</code> and <code>false</code> represent
their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_in_parallel(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_in_parallel()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.6.
</p></dd>
</dl>


<hr>
<a name="omp_005fin_005ffinal"></a>
<div class="header">
<p>
Next: <a href="#omp_005fis_005finitial_005fdevice" accesskey="n" rel="next">omp_is_initial_device</a>, Previous: <a href="#omp_005fin_005fparallel" accesskey="p" rel="prev">omp_in_parallel</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fin_005ffinal-_002d_002d-Whether-in-final-or-included-task-region"></a>
<h3 class="section">2.22 <code>omp_in_final</code> &ndash; Whether in final or included task region</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if currently running in a final
or included task region, <code>false</code> otherwise.  Here, <code>true</code>
and <code>false</code> represent their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_in_final(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_in_final()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.21.
</p></dd>
</dl>



<hr>
<a name="omp_005fis_005finitial_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fdefault_005fdevice" accesskey="n" rel="next">omp_set_default_device</a>, Previous: <a href="#omp_005fin_005ffinal" accesskey="p" rel="prev">omp_in_final</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fis_005finitial_005fdevice-_002d_002d-Whether-executing-on-the-host-device"></a>
<h3 class="section">2.23 <code>omp_is_initial_device</code> &ndash; Whether executing on the host device</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if currently running on the host device,
<code>false</code> otherwise.  Here, <code>true</code> and <code>false</code> represent
their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_is_initial_device(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_is_initial_device()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.34.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fdefault_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fdynamic" accesskey="n" rel="next">omp_set_dynamic</a>, Previous: <a href="#omp_005fis_005finitial_005fdevice" accesskey="p" rel="prev">omp_is_initial_device</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fdefault_005fdevice-_002d_002d-Set-the-default-device-for-target-regions"></a>
<h3 class="section">2.24 <code>omp_set_default_device</code> &ndash; Set the default device for target regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set the default device for target regions without device clause.  The argument
shall be a nonnegative device number.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_default_device(int device_num);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_default_device(device_num)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer device_num</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fDEFAULT_005fDEVICE">OMP_DEFAULT_DEVICE</a>, <a href="#omp_005fget_005fdefault_005fdevice">omp_get_default_device</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.29.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fdynamic"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fmax_005factive_005flevels" accesskey="n" rel="next">omp_set_max_active_levels</a>, Previous: <a href="#omp_005fset_005fdefault_005fdevice" accesskey="p" rel="prev">omp_set_default_device</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fdynamic-_002d_002d-Enable_002fdisable-dynamic-teams"></a>
<h3 class="section">2.25 <code>omp_set_dynamic</code> &ndash; Enable/disable dynamic teams</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable the dynamic adjustment of the number of threads 
within a team.  The function takes the language-specific equivalent
of <code>true</code> and <code>false</code>, where <code>true</code> enables dynamic 
adjustment of team sizes and <code>false</code> disables it.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_dynamic(int dynamic_threads);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_dynamic(dynamic_threads)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical, intent(in) :: dynamic_threads</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a>, <a href="#omp_005fget_005fdynamic">omp_get_dynamic</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.7.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fmax_005factive_005flevels"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnested" accesskey="n" rel="next">omp_set_nested</a>, Previous: <a href="#omp_005fset_005fdynamic" accesskey="p" rel="prev">omp_set_dynamic</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fmax_005factive_005flevels-_002d_002d-Limits-the-number-of-active-parallel-regions"></a>
<h3 class="section">2.26 <code>omp_set_max_active_levels</code> &ndash; Limits the number of active parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function limits the maximum allowed number of nested, active
parallel regions.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_max_active_levels(int max_levels);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_max_active_levels(max_levels)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer max_levels</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005factive_005flevels">omp_get_max_active_levels</a>, <a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.15.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fnested"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnum_005fthreads" accesskey="n" rel="next">omp_set_num_threads</a>, Previous: <a href="#omp_005fset_005fmax_005factive_005flevels" accesskey="p" rel="prev">omp_set_max_active_levels</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnested-_002d_002d-Enable_002fdisable-nested-parallel-regions"></a>
<h3 class="section">2.27 <code>omp_set_nested</code> &ndash; Enable/disable nested parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable nested parallel regions, i.e., whether team members
are allowed to create new teams.  The function takes the language-specific
equivalent of <code>true</code> and <code>false</code>, where <code>true</code> enables 
dynamic adjustment of team sizes and <code>false</code> disables it.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_nested(int nested);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_nested(nested)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical, intent(in) :: nested</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNESTED">OMP_NESTED</a>, <a href="#omp_005fget_005fnested">omp_get_nested</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.10.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fnum_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fschedule" accesskey="n" rel="next">omp_set_schedule</a>, Previous: <a href="#omp_005fset_005fnested" accesskey="p" rel="prev">omp_set_nested</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnum_005fthreads-_002d_002d-Set-upper-team-size-limit"></a>
<h3 class="section">2.28 <code>omp_set_num_threads</code> &ndash; Set upper team size limit</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the number of threads used by default in subsequent parallel 
sections, if those do not specify a <code>num_threads</code> clause.  The
argument of <code>omp_set_num_threads</code> shall be a positive integer.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_num_threads(int num_threads);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_num_threads(num_threads)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer, intent(in) :: num_threads</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>, <a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.1.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fschedule"></a>
<div class="header">
<p>
Next: <a href="#omp_005finit_005flock" accesskey="n" rel="next">omp_init_lock</a>, Previous: <a href="#omp_005fset_005fnum_005fthreads" accesskey="p" rel="prev">omp_set_num_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fschedule-_002d_002d-Set-the-runtime-scheduling-method"></a>
<h3 class="section">2.29 <code>omp_set_schedule</code> &ndash; Set the runtime scheduling method</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Sets the runtime scheduling method.  The <var>kind</var> argument can have the
value <code>omp_sched_static</code>, <code>omp_sched_dynamic</code>,
<code>omp_sched_guided</code> or <code>omp_sched_auto</code>.  Except for
<code>omp_sched_auto</code>, the chunk size is set to the value of
<var>chunk_size</var> if positive, or to the default value if zero or negative.
For <code>omp_sched_auto</code> the <var>chunk_size</var> argument is ignored.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_schedule(omp_sched_t kind, int chunk_size);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_schedule(kind, chunk_size)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=omp_sched_kind) kind</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer chunk_size</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fschedule">omp_get_schedule</a>
<a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.2.12.
</p></dd>
</dl>



<hr>
<a name="omp_005finit_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005flock" accesskey="n" rel="next">omp_set_lock</a>, Previous: <a href="#omp_005fset_005fschedule" accesskey="p" rel="prev">omp_set_schedule</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005finit_005flock-_002d_002d-Initialize-simple-lock"></a>
<h3 class="section">2.30 <code>omp_init_lock</code> &ndash; Initialize simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Initialize a simple lock.  After initialization, the lock is in
an unlocked state.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_init_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_init_lock(svar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(out) :: svar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fdestroy_005flock">omp_destroy_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.1.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005ftest_005flock" accesskey="n" rel="next">omp_test_lock</a>, Previous: <a href="#omp_005finit_005flock" accesskey="p" rel="prev">omp_init_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005flock-_002d_002d-Wait-for-and-set-simple-lock"></a>
<h3 class="section">2.31 <code>omp_set_lock</code> &ndash; Wait for and set simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a simple lock, the lock variable must be initialized by 
<code>omp_init_lock</code>.  The calling thread is blocked until the lock 
is available.  If the lock is already held by the current thread, 
a deadlock occurs.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_lock(svar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: svar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005ftest_005flock">omp_test_lock</a>, <a href="#omp_005funset_005flock">omp_unset_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.4.
</p></dd>
</dl>



<hr>
<a name="omp_005ftest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005funset_005flock" accesskey="n" rel="next">omp_unset_lock</a>, Previous: <a href="#omp_005fset_005flock" accesskey="p" rel="prev">omp_set_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005ftest_005flock-_002d_002d-Test-and-set-simple-lock-if-available"></a>
<h3 class="section">2.32 <code>omp_test_lock</code> &ndash; Test and set simple lock if available</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a simple lock, the lock variable must be initialized by 
<code>omp_init_lock</code>.  Contrary to <code>omp_set_lock</code>, <code>omp_test_lock</code> 
does not block if the lock is not available.  This function returns
<code>true</code> upon success, <code>false</code> otherwise.  Here, <code>true</code> and
<code>false</code> represent their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_test_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_test_lock(svar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: svar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.6.
</p></dd>
</dl>



<hr>
<a name="omp_005funset_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fdestroy_005flock" accesskey="n" rel="next">omp_destroy_lock</a>, Previous: <a href="#omp_005ftest_005flock" accesskey="p" rel="prev">omp_test_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005funset_005flock-_002d_002d-Unset-simple-lock"></a>
<h3 class="section">2.33 <code>omp_unset_lock</code> &ndash; Unset simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>A simple lock about to be unset must have been locked by <code>omp_set_lock</code>
or <code>omp_test_lock</code> before.  In addition, the lock must be held by the
thread calling <code>omp_unset_lock</code>.  Then, the lock becomes unlocked.  If one
or more threads attempted to set the lock before, one of them is chosen to,
again, set the lock to itself.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_unset_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_unset_lock(svar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: svar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005ftest_005flock">omp_test_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.5.
</p></dd>
</dl>



<hr>
<a name="omp_005fdestroy_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005finit_005fnest_005flock" accesskey="n" rel="next">omp_init_nest_lock</a>, Previous: <a href="#omp_005funset_005flock" accesskey="p" rel="prev">omp_unset_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fdestroy_005flock-_002d_002d-Destroy-simple-lock"></a>
<h3 class="section">2.34 <code>omp_destroy_lock</code> &ndash; Destroy simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Destroy a simple lock.  In order to be destroyed, a simple lock must be
in the unlocked state. 
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_destroy_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_destroy_lock(svar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: svar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.3.
</p></dd>
</dl>



<hr>
<a name="omp_005finit_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnest_005flock" accesskey="n" rel="next">omp_set_nest_lock</a>, Previous: <a href="#omp_005fdestroy_005flock" accesskey="p" rel="prev">omp_destroy_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005finit_005fnest_005flock-_002d_002d-Initialize-nested-lock"></a>
<h3 class="section">2.35 <code>omp_init_nest_lock</code> &ndash; Initialize nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Initialize a nested lock.  After initialization, the lock is in
an unlocked state and the nesting count is set to zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_init_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_init_nest_lock(nvar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(out) :: nvar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fdestroy_005fnest_005flock">omp_destroy_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.1.
</p></dd>
</dl>


<hr>
<a name="omp_005fset_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005ftest_005fnest_005flock" accesskey="n" rel="next">omp_test_nest_lock</a>, Previous: <a href="#omp_005finit_005fnest_005flock" accesskey="p" rel="prev">omp_init_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnest_005flock-_002d_002d-Wait-for-and-set-nested-lock"></a>
<h3 class="section">2.36 <code>omp_set_nest_lock</code> &ndash; Wait for and set nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a nested lock, the lock variable must be initialized by 
<code>omp_init_nest_lock</code>.  The calling thread is blocked until the lock
is available.  If the lock is already held by the current thread, the
nesting count for the lock is incremented.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_nest_lock(nvar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: nvar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005fnest_005flock">omp_init_nest_lock</a>, <a href="#omp_005funset_005fnest_005flock">omp_unset_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.4.
</p></dd>
</dl>



<hr>
<a name="omp_005ftest_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005funset_005fnest_005flock" accesskey="n" rel="next">omp_unset_nest_lock</a>, Previous: <a href="#omp_005fset_005fnest_005flock" accesskey="p" rel="prev">omp_set_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005ftest_005fnest_005flock-_002d_002d-Test-and-set-nested-lock-if-available"></a>
<h3 class="section">2.37 <code>omp_test_nest_lock</code> &ndash; Test and set nested lock if available</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a nested lock, the lock variable must be initialized by 
<code>omp_init_nest_lock</code>.  Contrary to <code>omp_set_nest_lock</code>,
<code>omp_test_nest_lock</code> does not block if the lock is not available. 
If the lock is already held by the current thread, the new nesting count 
is returned.  Otherwise, the return value equals zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_test_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_test_nest_lock(nvar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: nvar</code></td></tr>
</table>


</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.6.
</p></dd>
</dl>



<hr>
<a name="omp_005funset_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fdestroy_005fnest_005flock" accesskey="n" rel="next">omp_destroy_nest_lock</a>, Previous: <a href="#omp_005ftest_005fnest_005flock" accesskey="p" rel="prev">omp_test_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005funset_005fnest_005flock-_002d_002d-Unset-nested-lock"></a>
<h3 class="section">2.38 <code>omp_unset_nest_lock</code> &ndash; Unset nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>A nested lock about to be unset must have been locked by <code>omp_set_nested_lock</code>
or <code>omp_test_nested_lock</code> before.  In addition, the lock must be held by the
thread calling <code>omp_unset_nested_lock</code>.  If the nesting count drops to zero, the
lock becomes unlocked.  If one ore more threads attempted to set the lock before,
one of them is chosen to, again, set the lock to itself.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_unset_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_unset_nest_lock(nvar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: nvar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnest_005flock">omp_set_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.5.
</p></dd>
</dl>



<hr>
<a name="omp_005fdestroy_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fwtick" accesskey="n" rel="next">omp_get_wtick</a>, Previous: <a href="#omp_005funset_005fnest_005flock" accesskey="p" rel="prev">omp_unset_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fdestroy_005fnest_005flock-_002d_002d-Destroy-nested-lock"></a>
<h3 class="section">2.39 <code>omp_destroy_nest_lock</code> &ndash; Destroy nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Destroy a nested lock.  In order to be destroyed, a nested lock must be
in the unlocked state and its nesting count must equal zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_destroy_nest_lock(omp_nest_lock_t *);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_destroy_nest_lock(nvar)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: nvar</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.3.3.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fwtick"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fwtime" accesskey="n" rel="next">omp_get_wtime</a>, Previous: <a href="#omp_005fdestroy_005fnest_005flock" accesskey="p" rel="prev">omp_destroy_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fwtick-_002d_002d-Get-timer-precision"></a>
<h3 class="section">2.40 <code>omp_get_wtick</code> &ndash; Get timer precision</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Gets the timer precision, i.e., the number of seconds between two 
successive clock ticks.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>double omp_get_wtick(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>double precision function omp_get_wtick()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fwtime">omp_get_wtime</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.4.2.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fwtime"></a>
<div class="header">
<p>
Previous: <a href="#omp_005fget_005fwtick" accesskey="p" rel="prev">omp_get_wtick</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fwtime-_002d_002d-Elapsed-wall-clock-time"></a>
<h3 class="section">2.41 <code>omp_get_wtime</code> &ndash; Elapsed wall clock time</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Elapsed wall clock time in seconds.  The time is measured per thread, no
guarantee can be made that two distinct threads measure the same time.
Time is measured from some &quot;time in the past&quot;, which is an arbitrary time
guaranteed not to change during the execution of the program.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>double omp_get_wtime(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>double precision function omp_get_wtime()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fwtick">omp_get_wtick</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 3.4.1.
</p></dd>
</dl>




<hr>
<a name="Environment-Variables"></a>
<div class="header">
<p>
Next: <a href="#Enabling-OpenACC" accesskey="n" rel="next">Enabling OpenACC</a>, Previous: <a href="#Runtime-Library-Routines" accesskey="p" rel="prev">Runtime Library Routines</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Environment-Variables-1"></a>
<h2 class="chapter">3 Environment Variables</h2>

<p>The environment variables which beginning with <code>OMP_</code> are defined by
section 4 of the OpenMP specification in version 4.5, while those
beginning with <code>GOMP_</code> are GNU extensions.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fCANCELLATION" accesskey="1">OMP_CANCELLATION</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set whether cancellation is activated
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fDISPLAY_005fENV" accesskey="2">OMP_DISPLAY_ENV</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Show OpenMP version and environment variables
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fDEFAULT_005fDEVICE" accesskey="3">OMP_DEFAULT_DEVICE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the device used in target regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fDYNAMIC" accesskey="4">OMP_DYNAMIC</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Dynamic adjustment of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="5">OMP_MAX_ACTIVE_LEVELS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fMAX_005fTASK_005fPRIORITY" accesskey="6">OMP_MAX_TASK_PRIORITY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum task priority value
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fNESTED" accesskey="7">OMP_NESTED</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fNUM_005fTHREADS" accesskey="8">OMP_NUM_THREADS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies the number of threads to use
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fPROC_005fBIND" accesskey="9">OMP_PROC_BIND</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether theads may be moved between CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fPLACES">OMP_PLACES</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies on which CPUs the theads should be placed
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fSTACKSIZE">OMP_STACKSIZE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How threads are scheduled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fTHREAD_005fLIMIT">OMP_THREAD_LIMIT</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fWAIT_005fPOLICY">OMP_WAIT_POLICY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How waiting threads are handled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Bind threads to specific CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fDEBUG">GOMP_DEBUG</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable debugging output
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fSPINCOUNT">GOMP_SPINCOUNT</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the busy-wait spin count
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fRTEMS_005fTHREAD_005fPOOLS">GOMP_RTEMS_THREAD_POOLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the RTEMS specific thread pools
</td></tr>
</table>


<hr>
<a name="OMP_005fCANCELLATION"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fDISPLAY_005fENV" accesskey="n" rel="next">OMP_DISPLAY_ENV</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fCANCELLATION-_002d_002d-Set-whether-cancellation-is-activated"></a>
<h3 class="section">3.1 <code>OMP_CANCELLATION</code> &ndash; Set whether cancellation is activated</h3>
<a name="index-Environment-Variable"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>If set to <code>TRUE</code>, the cancellation is activated.  If set to <code>FALSE</code> or
if unset, cancellation is disabled and the <code>cancel</code> construct is ignored.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fcancellation">omp_get_cancellation</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.11
</p></dd>
</dl>



<hr>
<a name="OMP_005fDISPLAY_005fENV"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fDEFAULT_005fDEVICE" accesskey="n" rel="next">OMP_DEFAULT_DEVICE</a>, Previous: <a href="#OMP_005fCANCELLATION" accesskey="p" rel="prev">OMP_CANCELLATION</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fDISPLAY_005fENV-_002d_002d-Show-OpenMP-version-and-environment-variables"></a>
<h3 class="section">3.2 <code>OMP_DISPLAY_ENV</code> &ndash; Show OpenMP version and environment variables</h3>
<a name="index-Environment-Variable-1"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>If set to <code>TRUE</code>, the OpenMP version number and the values
associated with the OpenMP environment variables are printed to <code>stderr</code>.
If set to <code>VERBOSE</code>, it additionally shows the value of the environment
variables which are GNU extensions.  If undefined or set to <code>FALSE</code>,
this information will not be shown.
</p>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.12
</p></dd>
</dl>



<hr>
<a name="OMP_005fDEFAULT_005fDEVICE"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fDYNAMIC" accesskey="n" rel="next">OMP_DYNAMIC</a>, Previous: <a href="#OMP_005fDISPLAY_005fENV" accesskey="p" rel="prev">OMP_DISPLAY_ENV</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fDEFAULT_005fDEVICE-_002d_002d-Set-the-device-used-in-target-regions"></a>
<h3 class="section">3.3 <code>OMP_DEFAULT_DEVICE</code> &ndash; Set the device used in target regions</h3>
<a name="index-Environment-Variable-2"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set to choose the device which is used in a <code>target</code> region, unless the
value is overridden by <code>omp_set_default_device</code> or by a <code>device</code>
clause.  The value shall be the nonnegative device number. If no device with
the given device number exists, the code is executed on the host.  If unset,
device number 0 will be used.
</p>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fdefault_005fdevice">omp_get_default_device</a>, <a href="#omp_005fset_005fdefault_005fdevice">omp_set_default_device</a>,
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.13
</p></dd>
</dl>



<hr>
<a name="OMP_005fDYNAMIC"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="n" rel="next">OMP_MAX_ACTIVE_LEVELS</a>, Previous: <a href="#OMP_005fDEFAULT_005fDEVICE" accesskey="p" rel="prev">OMP_DEFAULT_DEVICE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fDYNAMIC-_002d_002d-Dynamic-adjustment-of-threads"></a>
<h3 class="section">3.4 <code>OMP_DYNAMIC</code> &ndash; Dynamic adjustment of threads</h3>
<a name="index-Environment-Variable-3"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable the dynamic adjustment of the number of threads 
within a team.  The value of this environment variable shall be 
<code>TRUE</code> or <code>FALSE</code>.  If undefined, dynamic adjustment is
disabled by default.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.3
</p></dd>
</dl>



<hr>
<a name="OMP_005fMAX_005fACTIVE_005fLEVELS"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fMAX_005fTASK_005fPRIORITY" accesskey="n" rel="next">OMP_MAX_TASK_PRIORITY</a>, Previous: <a href="#OMP_005fDYNAMIC" accesskey="p" rel="prev">OMP_DYNAMIC</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fMAX_005fACTIVE_005fLEVELS-_002d_002d-Set-the-maximum-number-of-nested-parallel-regions"></a>
<h3 class="section">3.5 <code>OMP_MAX_ACTIVE_LEVELS</code> &ndash; Set the maximum number of nested parallel regions</h3>
<a name="index-Environment-Variable-4"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the initial value for the maximum number of nested parallel
regions.  The value of this variable shall be a positive integer.
If undefined, the number of active levels is unlimited.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.9
</p></dd>
</dl>



<hr>
<a name="OMP_005fMAX_005fTASK_005fPRIORITY"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fNESTED" accesskey="n" rel="next">OMP_NESTED</a>, Previous: <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="p" rel="prev">OMP_MAX_ACTIVE_LEVELS</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fMAX_005fTASK_005fPRIORITY-_002d_002d-Set-the-maximum-priority"></a>
<h3 class="section">3.6 <code>OMP_MAX_TASK_PRIORITY</code> &ndash; Set the maximum priority</h3>
<p>number that can be set for a task.
<a name="index-Environment-Variable-5"></a>
</p><dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the initial value for the maximum priority value that can be
set for a task.  The value of this variable shall be a non-negative
integer, and zero is allowed.  If undefined, the default priority is
0.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005ftask_005fpriority">omp_get_max_task_priority</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.14
</p></dd>
</dl>



<hr>
<a name="OMP_005fNESTED"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fNUM_005fTHREADS" accesskey="n" rel="next">OMP_NUM_THREADS</a>, Previous: <a href="#OMP_005fMAX_005fTASK_005fPRIORITY" accesskey="p" rel="prev">OMP_MAX_TASK_PRIORITY</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fNESTED-_002d_002d-Nested-parallel-regions"></a>
<h3 class="section">3.7 <code>OMP_NESTED</code> &ndash; Nested parallel regions</h3>
<a name="index-Environment-Variable-6"></a>
<a name="index-Implementation-specific-setting"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable nested parallel regions, i.e., whether team members
are allowed to create new teams.  The value of this environment variable 
shall be <code>TRUE</code> or <code>FALSE</code>.  If undefined, nested parallel 
regions are disabled by default.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnested">omp_set_nested</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.6
</p></dd>
</dl>



<hr>
<a name="OMP_005fNUM_005fTHREADS"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fPROC_005fBIND" accesskey="n" rel="next">OMP_PROC_BIND</a>, Previous: <a href="#OMP_005fNESTED" accesskey="p" rel="prev">OMP_NESTED</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fNUM_005fTHREADS-_002d_002d-Specifies-the-number-of-threads-to-use"></a>
<h3 class="section">3.8 <code>OMP_NUM_THREADS</code> &ndash; Specifies the number of threads to use</h3>
<a name="index-Environment-Variable-7"></a>
<a name="index-Implementation-specific-setting-1"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the default number of threads to use in parallel regions.  The 
value of this variable shall be a comma-separated list of positive integers;
the value specified the number of threads to use for the corresponding nested
level.  If undefined one thread per CPU is used.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.2
</p></dd>
</dl>



<hr>
<a name="OMP_005fPROC_005fBIND"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fPLACES" accesskey="n" rel="next">OMP_PLACES</a>, Previous: <a href="#OMP_005fNUM_005fTHREADS" accesskey="p" rel="prev">OMP_NUM_THREADS</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fPROC_005fBIND-_002d_002d-Whether-theads-may-be-moved-between-CPUs"></a>
<h3 class="section">3.9 <code>OMP_PROC_BIND</code> &ndash; Whether theads may be moved between CPUs</h3>
<a name="index-Environment-Variable-8"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies whether threads may be moved between processors.  If set to
<code>TRUE</code>, OpenMP theads should not be moved; if set to <code>FALSE</code>
they may be moved.  Alternatively, a comma separated list with the
values <code>MASTER</code>, <code>CLOSE</code> and <code>SPREAD</code> can be used to specify
the thread affinity policy for the corresponding nesting level.  With
<code>MASTER</code> the worker threads are in the same place partition as the
master thread.  With <code>CLOSE</code> those are kept close to the master thread
in contiguous place partitions.  And with <code>SPREAD</code> a sparse distribution
across the place partitions is used.
</p>
<p>When undefined, <code>OMP_PROC_BIND</code> defaults to <code>TRUE</code> when
<code>OMP_PLACES</code> or <code>GOMP_CPU_AFFINITY</code> is set and <code>FALSE</code> otherwise.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fPLACES">OMP_PLACES</a>, <a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>, <a href="#omp_005fget_005fproc_005fbind">omp_get_proc_bind</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.4
</p></dd>
</dl>



<hr>
<a name="OMP_005fPLACES"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fSTACKSIZE" accesskey="n" rel="next">OMP_STACKSIZE</a>, Previous: <a href="#OMP_005fPROC_005fBIND" accesskey="p" rel="prev">OMP_PROC_BIND</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fPLACES-_002d_002d-Specifies-on-which-CPUs-the-theads-should-be-placed"></a>
<h3 class="section">3.10 <code>OMP_PLACES</code> &ndash; Specifies on which CPUs the theads should be placed</h3>
<a name="index-Environment-Variable-9"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>The thread placement can be either specified using an abstract name or by an
explicit list of the places.  The abstract names <code>threads</code>, <code>cores</code>
and <code>sockets</code> can be optionally followed by a positive number in
parentheses, which denotes the how many places shall be created.  With
<code>threads</code> each place corresponds to a single hardware thread; <code>cores</code>
to a single core with the corresponding number of hardware threads; and with
<code>sockets</code> the place corresponds to a single socket.  The resulting
placement can be shown by setting the <code>OMP_DISPLAY_ENV</code> environment
variable.
</p>
<p>Alternatively, the placement can be specified explicitly as comma-separated
list of places.  A place is specified by set of nonnegative numbers in curly
braces, denoting the denoting the hardware threads.  The hardware threads
belonging to a place can either be specified as comma-separated list of
nonnegative thread numbers or using an interval.  Multiple places can also be
either specified by a comma-separated list of places or by an interval.  To
specify an interval, a colon followed by the count is placed after after
the hardware thread number or the place.  Optionally, the length can be
followed by a colon and the stride number &ndash; otherwise a unit stride is
assumed.  For instance, the following specifies the same places list:
<code>&quot;{0,1,2}, {3,4,6}, {7,8,9}, {10,11,12}&quot;</code>;
<code>&quot;{0:3}, {3:3}, {7:3}, {10:3}&quot;</code>; and <code>&quot;{0:2}:4:3&quot;</code>.
</p>
<p>If <code>OMP_PLACES</code> and <code>GOMP_CPU_AFFINITY</code> are unset and
<code>OMP_PROC_BIND</code> is either unset or <code>false</code>, threads may be moved
between CPUs following no placement policy.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a>, <a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>, <a href="#omp_005fget_005fproc_005fbind">omp_get_proc_bind</a>,
<a href="#OMP_005fDISPLAY_005fENV">OMP_DISPLAY_ENV</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.5
</p></dd>
</dl>



<hr>
<a name="OMP_005fSTACKSIZE"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fSCHEDULE" accesskey="n" rel="next">OMP_SCHEDULE</a>, Previous: <a href="#OMP_005fPLACES" accesskey="p" rel="prev">OMP_PLACES</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size"></a>
<h3 class="section">3.11 <code>OMP_STACKSIZE</code> &ndash; Set default thread stack size</h3>
<a name="index-Environment-Variable-10"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set the default thread stack size in kilobytes, unless the number
is suffixed by <code>B</code>, <code>K</code>, <code>M</code> or <code>G</code>, in which
case the size is, respectively, in bytes, kilobytes, megabytes
or gigabytes.  This is different from <code>pthread_attr_setstacksize</code>
which gets the number of bytes as an argument.  If the stack size cannot
be set due to system constraints, an error is reported and the initial
stack size is left unchanged.  If undefined, the stack size is system
dependent.
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.7
</p></dd>
</dl>



<hr>
<a name="OMP_005fSCHEDULE"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fTHREAD_005fLIMIT" accesskey="n" rel="next">OMP_THREAD_LIMIT</a>, Previous: <a href="#OMP_005fSTACKSIZE" accesskey="p" rel="prev">OMP_STACKSIZE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fSCHEDULE-_002d_002d-How-threads-are-scheduled"></a>
<h3 class="section">3.12 <code>OMP_SCHEDULE</code> &ndash; How threads are scheduled</h3>
<a name="index-Environment-Variable-11"></a>
<a name="index-Implementation-specific-setting-2"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Allows to specify <code>schedule type</code> and <code>chunk size</code>. 
The value of the variable shall have the form: <code>type[,chunk]</code> where
<code>type</code> is one of <code>static</code>, <code>dynamic</code>, <code>guided</code> or <code>auto</code>
The optional <code>chunk</code> size shall be a positive integer.  If undefined,
dynamic scheduling and a chunk size of 1 is used.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fschedule">omp_set_schedule</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Sections 2.7.1.1 and 4.1
</p></dd>
</dl>



<hr>
<a name="OMP_005fTHREAD_005fLIMIT"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fWAIT_005fPOLICY" accesskey="n" rel="next">OMP_WAIT_POLICY</a>, Previous: <a href="#OMP_005fSCHEDULE" accesskey="p" rel="prev">OMP_SCHEDULE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fTHREAD_005fLIMIT-_002d_002d-Set-the-maximum-number-of-threads"></a>
<h3 class="section">3.13 <code>OMP_THREAD_LIMIT</code> &ndash; Set the maximum number of threads</h3>
<a name="index-Environment-Variable-12"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the number of threads to use for the whole program.  The
value of this variable shall be a positive integer.  If undefined,
the number of threads is not limited.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>, <a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.10
</p></dd>
</dl>



<hr>
<a name="OMP_005fWAIT_005fPOLICY"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fCPU_005fAFFINITY" accesskey="n" rel="next">GOMP_CPU_AFFINITY</a>, Previous: <a href="#OMP_005fTHREAD_005fLIMIT" accesskey="p" rel="prev">OMP_THREAD_LIMIT</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fWAIT_005fPOLICY-_002d_002d-How-waiting-threads-are-handled"></a>
<h3 class="section">3.14 <code>OMP_WAIT_POLICY</code> &ndash; How waiting threads are handled</h3>
<a name="index-Environment-Variable-13"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies whether waiting threads should be active or passive.  If
the value is <code>PASSIVE</code>, waiting threads should not consume CPU
power while waiting; while the value is <code>ACTIVE</code> specifies that
they should.  If undefined, threads wait actively for a short time
before waiting passively.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#GOMP_005fSPINCOUNT">GOMP_SPINCOUNT</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specification v4.5</a>, Section 4.8
</p></dd>
</dl>



<hr>
<a name="GOMP_005fCPU_005fAFFINITY"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fDEBUG" accesskey="n" rel="next">GOMP_DEBUG</a>, Previous: <a href="#OMP_005fWAIT_005fPOLICY" accesskey="p" rel="prev">OMP_WAIT_POLICY</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fCPU_005fAFFINITY-_002d_002d-Bind-threads-to-specific-CPUs"></a>
<h3 class="section">3.15 <code>GOMP_CPU_AFFINITY</code> &ndash; Bind threads to specific CPUs</h3>
<a name="index-Environment-Variable-14"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Binds threads to specific CPUs.  The variable should contain a space-separated
or comma-separated list of CPUs.  This list may contain different kinds of 
entries: either single CPU numbers in any order, a range of CPUs (M-N) 
or a range with some stride (M-N:S).  CPU numbers are zero based.  For example,
<code>GOMP_CPU_AFFINITY=&quot;0 3 1-2 4-15:2&quot;</code> will bind the initial thread
to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to 
CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8, 10, 12,
and 14 respectively and then start assigning back from the beginning of
the list.  <code>GOMP_CPU_AFFINITY=0</code> binds all threads to CPU 0.
</p>
<p>There is no libgomp library routine to determine whether a CPU affinity
specification is in effect.  As a workaround, language-specific library 
functions, e.g., <code>getenv</code> in C or <code>GET_ENVIRONMENT_VARIABLE</code> in 
Fortran, may be used to query the setting of the <code>GOMP_CPU_AFFINITY</code> 
environment variable.  A defined CPU affinity on startup cannot be changed 
or disabled during the runtime of the application.
</p>
<p>If both <code>GOMP_CPU_AFFINITY</code> and <code>OMP_PROC_BIND</code> are set,
<code>OMP_PROC_BIND</code> has a higher precedence.  If neither has been set and
<code>OMP_PROC_BIND</code> is unset, or when <code>OMP_PROC_BIND</code> is set to
<code>FALSE</code>, the host system will handle the assignment of threads to CPUs.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fPLACES">OMP_PLACES</a>, <a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a>
</p></dd>
</dl>



<hr>
<a name="GOMP_005fDEBUG"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fSTACKSIZE" accesskey="n" rel="next">GOMP_STACKSIZE</a>, Previous: <a href="#GOMP_005fCPU_005fAFFINITY" accesskey="p" rel="prev">GOMP_CPU_AFFINITY</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fDEBUG-_002d_002d-Enable-debugging-output"></a>
<h3 class="section">3.16 <code>GOMP_DEBUG</code> &ndash; Enable debugging output</h3>
<a name="index-Environment-Variable-15"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable debugging output.  The variable should be set to <code>0</code>
(disabled, also the default if not set), or <code>1</code> (enabled).
</p>
<p>If enabled, some debugging output will be printed during execution.
This is currently not specified in more detail, and subject to change.
</p></dd>
</dl>



<hr>
<a name="GOMP_005fSTACKSIZE"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fSPINCOUNT" accesskey="n" rel="next">GOMP_SPINCOUNT</a>, Previous: <a href="#GOMP_005fDEBUG" accesskey="p" rel="prev">GOMP_DEBUG</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size"></a>
<h3 class="section">3.17 <code>GOMP_STACKSIZE</code> &ndash; Set default thread stack size</h3>
<a name="index-Environment-Variable-16"></a>
<a name="index-Implementation-specific-setting-3"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set the default thread stack size in kilobytes.  This is different from
<code>pthread_attr_setstacksize</code> which gets the number of bytes as an 
argument.  If the stack size cannot be set due to system constraints, an 
error is reported and the initial stack size is left unchanged.  If undefined,
the stack size is system dependent.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fSTACKSIZE">OMP_STACKSIZE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00493.html">GCC Patches Mailinglist</a>, 
<a href="http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00496.html">GCC Patches Mailinglist</a>
</p></dd>
</dl>



<hr>
<a name="GOMP_005fSPINCOUNT"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fRTEMS_005fTHREAD_005fPOOLS" accesskey="n" rel="next">GOMP_RTEMS_THREAD_POOLS</a>, Previous: <a href="#GOMP_005fSTACKSIZE" accesskey="p" rel="prev">GOMP_STACKSIZE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fSPINCOUNT-_002d_002d-Set-the-busy_002dwait-spin-count"></a>
<h3 class="section">3.18 <code>GOMP_SPINCOUNT</code> &ndash; Set the busy-wait spin count</h3>
<a name="index-Environment-Variable-17"></a>
<a name="index-Implementation-specific-setting-4"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Determines how long a threads waits actively with consuming CPU power
before waiting passively without consuming CPU power.  The value may be
either <code>INFINITE</code>, <code>INFINITY</code> to always wait actively or an
integer which gives the number of spins of the busy-wait loop.  The
integer may optionally be followed by the following suffixes acting
as multiplication factors: <code>k</code> (kilo, thousand), <code>M</code> (mega,
million), <code>G</code> (giga, billion), or <code>T</code> (tera, trillion).
If undefined, 0 is used when <code>OMP_WAIT_POLICY</code> is <code>PASSIVE</code>,
300,000 is used when <code>OMP_WAIT_POLICY</code> is undefined and
30 billion is used when <code>OMP_WAIT_POLICY</code> is <code>ACTIVE</code>.
If there are more OpenMP threads than available CPUs, 1000 and 100
spins are used for <code>OMP_WAIT_POLICY</code> being <code>ACTIVE</code> or
undefined, respectively; unless the <code>GOMP_SPINCOUNT</code> is lower
or <code>OMP_WAIT_POLICY</code> is <code>PASSIVE</code>.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fWAIT_005fPOLICY">OMP_WAIT_POLICY</a>
</p></dd>
</dl>



<hr>
<a name="GOMP_005fRTEMS_005fTHREAD_005fPOOLS"></a>
<div class="header">
<p>
Previous: <a href="#GOMP_005fSPINCOUNT" accesskey="p" rel="prev">GOMP_SPINCOUNT</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fRTEMS_005fTHREAD_005fPOOLS-_002d_002d-Set-the-RTEMS-specific-thread-pools"></a>
<h3 class="section">3.19 <code>GOMP_RTEMS_THREAD_POOLS</code> &ndash; Set the RTEMS specific thread pools</h3>
<a name="index-Environment-Variable-18"></a>
<a name="index-Implementation-specific-setting-5"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This environment variable is only used on the RTEMS real-time operating system.
It determines the scheduler instance specific thread pools.  The format for
<code>GOMP_RTEMS_THREAD_POOLS</code> is a list of optional
<code>&lt;thread-pool-count&gt;[$&lt;priority&gt;]@&lt;scheduler-name&gt;</code> configurations
separated by <code>:</code> where:
</p><ul>
<li> <code>&lt;thread-pool-count&gt;</code> is the thread pool count for this scheduler
instance.
</li><li> <code>$&lt;priority&gt;</code> is an optional priority for the worker threads of a
thread pool according to <code>pthread_setschedparam</code>.  In case a priority
value is omitted, then a worker thread will inherit the priority of the OpenMP
master thread that created it.  The priority of the worker thread is not
changed after creation, even if a new OpenMP master thread using the worker has
a different priority.
</li><li> <code>@&lt;scheduler-name&gt;</code> is the scheduler instance name according to the
RTEMS application configuration.
</li></ul>
<p>In case no thread pool configuration is specified for a scheduler instance,
then each OpenMP master thread of this scheduler instance will use its own
dynamically allocated thread pool.  To limit the worker thread count of the
thread pools, each OpenMP master thread must call <code>omp_set_num_threads</code>.
</p></dd>
<dt><em>Example</em>:</dt>
<dd><p>Lets suppose we have three scheduler instances <code>IO</code>, <code>WRK0</code>, and
<code>WRK1</code> with <code>GOMP_RTEMS_THREAD_POOLS</code> set to
<code>&quot;1@WRK0:3$4@WRK1&quot;</code>.  Then there are no thread pool restrictions for
scheduler instance <code>IO</code>.  In the scheduler instance <code>WRK0</code> there is
one thread pool available.  Since no priority is specified for this scheduler
instance, the worker thread inherits the priority of the OpenMP master thread
that created it.  In the scheduler instance <code>WRK1</code> there are three thread
pools available and their worker threads run at priority four.
</p></dd>
</dl>




<hr>
<a name="Enabling-OpenACC"></a>
<div class="header">
<p>
Next: <a href="#OpenACC-Runtime-Library-Routines" accesskey="n" rel="next">OpenACC Runtime Library Routines</a>, Previous: <a href="#Environment-Variables" accesskey="p" rel="prev">Environment Variables</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Enabling-OpenACC-1"></a>
<h2 class="chapter">4 Enabling OpenACC</h2>

<p>To activate the OpenACC extensions for C/C++ and Fortran, the compile-time 
flag <samp>-fopenacc</samp> must be specified.  This enables the OpenACC directive
<code>#pragma acc</code> in C/C++ and <code>!$accp</code> directives in free form,
<code>c$acc</code>, <code>*$acc</code> and <code>!$acc</code> directives in fixed form,
<code>!$</code> conditional compilation sentinels in free form and <code>c$</code>,
<code>*$</code> and <code>!$</code> sentinels in fixed form, for Fortran.  The flag also
arranges for automatic linking of the OpenACC runtime library 
(<a href="#OpenACC-Runtime-Library-Routines">OpenACC Runtime Library Routines</a>).
</p>
<p>A complete description of all OpenACC directives accepted may be found in 
the <a href="https://www.openacc.org">OpenACC</a> Application Programming
Interface manual, version 2.0.
</p>
<p>Note that this is an experimental feature and subject to
change in future versions of GCC.  See
<a href="https://gcc.gnu.org/wiki/OpenACC">https://gcc.gnu.org/wiki/OpenACC</a> for more information.
</p>



<hr>
<a name="OpenACC-Runtime-Library-Routines"></a>
<div class="header">
<p>
Next: <a href="#OpenACC-Environment-Variables" accesskey="n" rel="next">OpenACC Environment Variables</a>, Previous: <a href="#Enabling-OpenACC" accesskey="p" rel="prev">Enabling OpenACC</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OpenACC-Runtime-Library-Routines-1"></a>
<h2 class="chapter">5 OpenACC Runtime Library Routines</h2>

<p>The runtime routines described here are defined by section 3 of the OpenACC
specifications in version 2.0.
They have C linkage, and do not throw exceptions.
Generally, they are available only for the host, with the exception of
<code>acc_on_device</code>, which is available for both the host and the
acceleration device.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fnum_005fdevices" accesskey="1">acc_get_num_devices</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get number of devices for the given device
                                type.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fset_005fdevice_005ftype" accesskey="2">acc_set_device_type</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set type of device accelerator to use.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fdevice_005ftype" accesskey="3">acc_get_device_type</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get type of device accelerator to be used.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fset_005fdevice_005fnum" accesskey="4">acc_set_device_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set device number to use.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fdevice_005fnum" accesskey="5">acc_get_device_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get device number to be used.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fasync_005ftest" accesskey="6">acc_async_test</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Tests for completion of a specific asynchronous
                                operation.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fasync_005ftest_005fall" accesskey="7">acc_async_test_all</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Tests for completion of all asychronous
                                operations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fwait" accesskey="8">acc_wait</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for completion of a specific asynchronous
                                operation.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fwait_005fall" accesskey="9">acc_wait_all</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Waits for completion of all asyncrhonous
                                operations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fwait_005fall_005fasync">acc_wait_all_async</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for completion of all asynchronous
                                operations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fwait_005fasync">acc_wait_async</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for completion of asynchronous operations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005finit">acc_init</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Initialize runtime for a specific device type.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fshutdown">acc_shutdown</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Shuts down the runtime for a specific device
                                type.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fon_005fdevice">acc_on_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether executing on a particular device
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fmalloc">acc_malloc</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Allocate device memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005ffree">acc_free</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Free device memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fcopyin">acc_copyin</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Allocate device memory and copy host memory to
                                it.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fpresent_005for_005fcopyin">acc_present_or_copyin</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">If the data is not present on the device,
                                allocate device memory and copy from host
                                memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fcreate">acc_create</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Allocate device memory and map it to host
                                memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fpresent_005for_005fcreate">acc_present_or_create</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">If the data is not present on the device,
                                allocate device memory and map it to host
                                memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fcopyout">acc_copyout</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Copy device memory to host memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fdelete">acc_delete</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Free device memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fupdate_005fdevice">acc_update_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Update device memory from mapped host memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fupdate_005fself">acc_update_self</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Update host memory from mapped device memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fmap_005fdata">acc_map_data</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Map previously allocated device memory to host
                                memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005funmap_005fdata">acc_unmap_data</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Unmap device memory from host memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fdeviceptr">acc_deviceptr</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get device pointer associated with specific
                                host address.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fhostptr">acc_hostptr</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get host pointer associated with specific
                                device address.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fis_005fpresent">acc_is_present</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Indiciate whether host variable / array is
                                present on device.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fmemcpy_005fto_005fdevice">acc_memcpy_to_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Copy host memory to device memory.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fmemcpy_005ffrom_005fdevice">acc_memcpy_from_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Copy device memory to host memory.
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">

API routines for target platforms.

</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fcurrent_005fcuda_005fdevice">acc_get_current_cuda_device</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get CUDA device handle.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fcurrent_005fcuda_005fcontext">acc_get_current_cuda_context</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get CUDA context handle.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fget_005fcuda_005fstream">acc_get_cuda_stream</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get CUDA stream handle.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#acc_005fset_005fcuda_005fstream">acc_set_cuda_stream</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set CUDA stream handle.
</td></tr>
</table>



<hr>
<a name="acc_005fget_005fnum_005fdevices"></a>
<div class="header">
<p>
Next: <a href="#acc_005fset_005fdevice_005ftype" accesskey="n" rel="next">acc_set_device_type</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fnum_005fdevices-_002d_002d-Get-number-of-devices-for-given-device-type"></a>
<h3 class="section">5.1 <code>acc_get_num_devices</code> &ndash; Get number of devices for given device type</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns a value indicating the number of devices available
for the device type specified in <var>devicetype</var>. 
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int acc_get_num_devices(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function acc_get_num_devices(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_device_kind) devicetype</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.1.
</p></dd>
</dl>



<hr>
<a name="acc_005fset_005fdevice_005ftype"></a>
<div class="header">
<p>
Next: <a href="#acc_005fget_005fdevice_005ftype" accesskey="n" rel="next">acc_get_device_type</a>, Previous: <a href="#acc_005fget_005fnum_005fdevices" accesskey="p" rel="prev">acc_get_num_devices</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fset_005fdevice_005ftype-_002d_002d-Set-type-of-device-accelerator-to-use_002e"></a>
<h3 class="section">5.2 <code>acc_set_device_type</code> &ndash; Set type of device accelerator to use.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function indicates to the runtime library which device typr, specified
in <var>devicetype</var>, to use when executing a parallel or kernels region. 
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_set_device_type(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_set_device_type(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_device_kind) devicetype</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.2.
</p></dd>
</dl>



<hr>
<a name="acc_005fget_005fdevice_005ftype"></a>
<div class="header">
<p>
Next: <a href="#acc_005fset_005fdevice_005fnum" accesskey="n" rel="next">acc_set_device_num</a>, Previous: <a href="#acc_005fset_005fdevice_005ftype" accesskey="p" rel="prev">acc_set_device_type</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fdevice_005ftype-_002d_002d-Get-type-of-device-accelerator-to-be-used_002e"></a>
<h3 class="section">5.3 <code>acc_get_device_type</code> &ndash; Get type of device accelerator to be used.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns what device type will be used when executing a
parallel or kernels region.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_device_t acc_get_device_type(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_get_device_type(void)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_device_kind) acc_get_device_type</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.3.
</p></dd>
</dl>



<hr>
<a name="acc_005fset_005fdevice_005fnum"></a>
<div class="header">
<p>
Next: <a href="#acc_005fget_005fdevice_005fnum" accesskey="n" rel="next">acc_get_device_num</a>, Previous: <a href="#acc_005fget_005fdevice_005ftype" accesskey="p" rel="prev">acc_get_device_type</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fset_005fdevice_005fnum-_002d_002d-Set-device-number-to-use_002e"></a>
<h3 class="section">5.4 <code>acc_set_device_num</code> &ndash; Set device number to use.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function will indicate to the runtime which device number,
specified by <var>num</var>, associated with the specifed device
type <var>devicetype</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_set_device_num(int num, acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_set_device_num(devicenum, devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer devicenum</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_device_kind) devicetype</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.4.
</p></dd>
</dl>



<hr>
<a name="acc_005fget_005fdevice_005fnum"></a>
<div class="header">
<p>
Next: <a href="#acc_005fasync_005ftest" accesskey="n" rel="next">acc_async_test</a>, Previous: <a href="#acc_005fset_005fdevice_005fnum" accesskey="p" rel="prev">acc_set_device_num</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fdevice_005fnum-_002d_002d-Get-device-number-to-be-used_002e"></a>
<h3 class="section">5.5 <code>acc_get_device_num</code> &ndash; Get device number to be used.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns which device number associated with the specified device
type <var>devicetype</var>, will be used when executing a parallel or kernels
region.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int acc_get_device_num(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_get_device_num(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_device_kind) devicetype</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer acc_get_device_num</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.5.
</p></dd>
</dl>



<hr>
<a name="acc_005fasync_005ftest"></a>
<div class="header">
<p>
Next: <a href="#acc_005fasync_005ftest_005fall" accesskey="n" rel="next">acc_async_test_all</a>, Previous: <a href="#acc_005fget_005fdevice_005fnum" accesskey="p" rel="prev">acc_get_device_num</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fasync_005ftest-_002d_002d-Test-for-completion-of-a-specific-asynchronous-operation_002e"></a>
<h3 class="section">5.6 <code>acc_async_test</code> &ndash; Test for completion of a specific asynchronous operation.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function tests for completion of the asynchrounous operation specified
in <var>arg</var>. In C/C++, a non-zero value will be returned to indicate
the specified asynchronous operation has completed. While Fortran will return
a <code>true</code>. If the asynchrounous operation has not completed, C/C++ returns
a zero and Fortran returns a <code>false</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int acc_async_test(int arg);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_async_test(arg)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=acc_handle_kind) arg</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical acc_async_test</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.6.
</p></dd>
</dl>



<hr>
<a name="acc_005fasync_005ftest_005fall"></a>
<div class="header">
<p>
Next: <a href="#acc_005fwait" accesskey="n" rel="next">acc_wait</a>, Previous: <a href="#acc_005fasync_005ftest" accesskey="p" rel="prev">acc_async_test</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fasync_005ftest_005fall-_002d_002d-Tests-for-completion-of-all-asynchronous-operations_002e"></a>
<h3 class="section">5.7 <code>acc_async_test_all</code> &ndash; Tests for completion of all asynchronous operations.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function tests for completion of all asynchrounous operations.
In C/C++, a non-zero value will be returned to indicate all asynchronous
operations have completed. While Fortran will return a <code>true</code>. If
any asynchronous operation has not completed, C/C++ returns a zero and
Fortran returns a <code>false</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int acc_async_test_all(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_async_test()</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical acc_get_device_num</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.7.
</p></dd>
</dl>



<hr>
<a name="acc_005fwait"></a>
<div class="header">
<p>
Next: <a href="#acc_005fwait_005fall" accesskey="n" rel="next">acc_wait_all</a>, Previous: <a href="#acc_005fasync_005ftest_005fall" accesskey="p" rel="prev">acc_async_test_all</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fwait-_002d_002d-Wait-for-completion-of-a-specific-asynchronous-operation_002e"></a>
<h3 class="section">5.8 <code>acc_wait</code> &ndash; Wait for completion of a specific asynchronous operation.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function waits for completion of the asynchronous operation
specified in <var>arg</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_wait(arg);</code></td></tr>
<tr><td width="20%"><em>Prototype (OpenACC 1.0 compatibility)</em>:</td><td width="80%"><code>acc_async_wait(arg);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_wait(arg)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_handle_kind) arg</code></td></tr>
<tr><td width="20%"><em>Interface (OpenACC 1.0 compatibility)</em>:</td><td width="80%"><code>subroutine acc_async_wait(arg)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_handle_kind) arg</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.8.
</p></dd>
</dl>



<hr>
<a name="acc_005fwait_005fall"></a>
<div class="header">
<p>
Next: <a href="#acc_005fwait_005fall_005fasync" accesskey="n" rel="next">acc_wait_all_async</a>, Previous: <a href="#acc_005fwait" accesskey="p" rel="prev">acc_wait</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fwait_005fall-_002d_002d-Waits-for-completion-of-all-asynchronous-operations_002e"></a>
<h3 class="section">5.9 <code>acc_wait_all</code> &ndash; Waits for completion of all asynchronous operations.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function waits for the completion of all asynchronous operations.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_wait_all(void);</code></td></tr>
<tr><td width="20%"><em>Prototype (OpenACC 1.0 compatibility)</em>:</td><td width="80%"><code>acc_async_wait_all(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_wait_all()</code></td></tr>
<tr><td width="20%"><em>Interface (OpenACC 1.0 compatibility)</em>:</td><td width="80%"><code>subroutine acc_async_wait_all()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.10.
</p></dd>
</dl>



<hr>
<a name="acc_005fwait_005fall_005fasync"></a>
<div class="header">
<p>
Next: <a href="#acc_005fwait_005fasync" accesskey="n" rel="next">acc_wait_async</a>, Previous: <a href="#acc_005fwait_005fall" accesskey="p" rel="prev">acc_wait_all</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fwait_005fall_005fasync-_002d_002d-Wait-for-completion-of-all-asynchronous-operations_002e"></a>
<h3 class="section">5.10 <code>acc_wait_all_async</code> &ndash; Wait for completion of all asynchronous operations.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function enqueues a wait operation on the queue <var>async</var> for any
and all asynchronous operations that have been previously enqueued on
any queue.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_wait_all_async(int async);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_wait_all_async(async)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_handle_kind) async</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.11.
</p></dd>
</dl>



<hr>
<a name="acc_005fwait_005fasync"></a>
<div class="header">
<p>
Next: <a href="#acc_005finit" accesskey="n" rel="next">acc_init</a>, Previous: <a href="#acc_005fwait_005fall_005fasync" accesskey="p" rel="prev">acc_wait_all_async</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fwait_005fasync-_002d_002d-Wait-for-completion-of-asynchronous-operations_002e"></a>
<h3 class="section">5.11 <code>acc_wait_async</code> &ndash; Wait for completion of asynchronous operations.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function enqueues a wait operation on queue <var>async</var> for any and all
asynchronous operations enqueued on queue <var>arg</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_wait_async(int arg, int async);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_wait_async(arg, async)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_handle_kind) arg, async</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.9.
</p></dd>
</dl>



<hr>
<a name="acc_005finit"></a>
<div class="header">
<p>
Next: <a href="#acc_005fshutdown" accesskey="n" rel="next">acc_shutdown</a>, Previous: <a href="#acc_005fwait_005fasync" accesskey="p" rel="prev">acc_wait_async</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005finit-_002d_002d-Initialize-runtime-for-a-specific-device-type_002e"></a>
<h3 class="section">5.12 <code>acc_init</code> &ndash; Initialize runtime for a specific device type.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function initializes the runtime for the device type specified in
<var>devicetype</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_init(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_init(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_device_kind) devicetype</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.12.
</p></dd>
</dl>



<hr>
<a name="acc_005fshutdown"></a>
<div class="header">
<p>
Next: <a href="#acc_005fon_005fdevice" accesskey="n" rel="next">acc_on_device</a>, Previous: <a href="#acc_005finit" accesskey="p" rel="prev">acc_init</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fshutdown-_002d_002d-Shuts-down-the-runtime-for-a-specific-device-type_002e"></a>
<h3 class="section">5.13 <code>acc_shutdown</code> &ndash; Shuts down the runtime for a specific device type.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function shuts down the runtime for the device type specified in
<var>devicetype</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_shutdown(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_shutdown(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_device_kind) devicetype</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.13.
</p></dd>
</dl>



<hr>
<a name="acc_005fon_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#acc_005fmalloc" accesskey="n" rel="next">acc_malloc</a>, Previous: <a href="#acc_005fshutdown" accesskey="p" rel="prev">acc_shutdown</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fon_005fdevice-_002d_002d-Whether-executing-on-a-particular-device"></a>
<h3 class="section">5.14 <code>acc_on_device</code> &ndash; Whether executing on a particular device</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns whether the program is executing on a particular
device specified in <var>devicetype</var>. In C/C++ a non-zero value is
returned to indicate the device is execiting on the specified device type.
In Fortran, <code>true</code> will be returned. If the program is not executing
on the specified device type C/C++ will return a zero, while Fortran will
return <code>false</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_on_device(acc_device_t devicetype);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_on_device(devicetype)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(acc_device_kind) devicetype</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical acc_on_device</code></td></tr>
</table>


</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.14.
</p></dd>
</dl>



<hr>
<a name="acc_005fmalloc"></a>
<div class="header">
<p>
Next: <a href="#acc_005ffree" accesskey="n" rel="next">acc_free</a>, Previous: <a href="#acc_005fon_005fdevice" accesskey="p" rel="prev">acc_on_device</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fmalloc-_002d_002d-Allocate-device-memory_002e"></a>
<h3 class="section">5.15 <code>acc_malloc</code> &ndash; Allocate device memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function allocates <var>len</var> bytes of device memory. It returns
the device address of the allocated memory.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>d_void* acc_malloc(size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.15.
</p></dd>
</dl>



<hr>
<a name="acc_005ffree"></a>
<div class="header">
<p>
Next: <a href="#acc_005fcopyin" accesskey="n" rel="next">acc_copyin</a>, Previous: <a href="#acc_005fmalloc" accesskey="p" rel="prev">acc_malloc</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005ffree-_002d_002d-Free-device-memory_002e"></a>
<h3 class="section">5.16 <code>acc_free</code> &ndash; Free device memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>Free previously allocated device memory at the device address <code>a</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_free(d_void *a);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.16.
</p></dd>
</dl>



<hr>
<a name="acc_005fcopyin"></a>
<div class="header">
<p>
Next: <a href="#acc_005fpresent_005for_005fcopyin" accesskey="n" rel="next">acc_present_or_copyin</a>, Previous: <a href="#acc_005ffree" accesskey="p" rel="prev">acc_free</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fcopyin-_002d_002d-Allocate-device-memory-and-copy-host-memory-to-it_002e"></a>
<h3 class="section">5.17 <code>acc_copyin</code> &ndash; Allocate device memory and copy host memory to it.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>In C/C++, this function allocates <var>len</var> bytes of device memory
and maps it to the specified host address in <var>a</var>. The device
address of the newly allocated device memory is returned.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a
variable or array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_copyin(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_copyin(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_copyin(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.17.
</p></dd>
</dl>



<hr>
<a name="acc_005fpresent_005for_005fcopyin"></a>
<div class="header">
<p>
Next: <a href="#acc_005fcreate" accesskey="n" rel="next">acc_create</a>, Previous: <a href="#acc_005fcopyin" accesskey="p" rel="prev">acc_copyin</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fpresent_005for_005fcopyin-_002d_002d-If-the-data-is-not-present-on-the-device_002c-allocate-device-memory-and-copy-from-host-memory_002e"></a>
<h3 class="section">5.18 <code>acc_present_or_copyin</code> &ndash; If the data is not present on the device, allocate device memory and copy from host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function tests if the host data specifed by <var>a</var> and of length
<var>len</var> is present or not. If it is not present, then device memory
will be allocated and the host memory copied. The device address of
the newly allocated device memory is returned.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_present_or_copyin(h_void *a, size_t len);</code></td></tr>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_pcopyin(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_present_or_copyin(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_present_or_copyin(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_pcopyin(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_pcopyin(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.18.
</p></dd>
</dl>



<hr>
<a name="acc_005fcreate"></a>
<div class="header">
<p>
Next: <a href="#acc_005fpresent_005for_005fcreate" accesskey="n" rel="next">acc_present_or_create</a>, Previous: <a href="#acc_005fpresent_005for_005fcopyin" accesskey="p" rel="prev">acc_present_or_copyin</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fcreate-_002d_002d-Allocate-device-memory-and-map-it-to-host-memory_002e"></a>
<h3 class="section">5.19 <code>acc_create</code> &ndash; Allocate device memory and map it to host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function allocates device memory and maps it to host memory specified
by the host address <var>a</var> with a length of <var>len</var> bytes. In C/C++,
the function returns the device address of the allocated device memory.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_create(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_create(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_create(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.19.
</p></dd>
</dl>



<hr>
<a name="acc_005fpresent_005for_005fcreate"></a>
<div class="header">
<p>
Next: <a href="#acc_005fcopyout" accesskey="n" rel="next">acc_copyout</a>, Previous: <a href="#acc_005fcreate" accesskey="p" rel="prev">acc_create</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fpresent_005for_005fcreate-_002d_002d-If-the-data-is-not-present-on-the-device_002c-allocate-device-memory-and-map-it-to-host-memory_002e"></a>
<h3 class="section">5.20 <code>acc_present_or_create</code> &ndash; If the data is not present on the device, allocate device memory and map it to host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function tests if the host data specifed by <var>a</var> and of length
<var>len</var> is present or not. If it is not present, then device memory
will be allocated and mapped to host memory. In C/C++, the device address
of the newly allocated device memory is returned.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>

</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_present_or_create(h_void *a, size_t len)</code></td></tr>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_pcreate(h_void *a, size_t len)</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_present_or_create(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_present_or_create(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_pcreate(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_pcreate(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.20.
</p></dd>
</dl>



<hr>
<a name="acc_005fcopyout"></a>
<div class="header">
<p>
Next: <a href="#acc_005fdelete" accesskey="n" rel="next">acc_delete</a>, Previous: <a href="#acc_005fpresent_005for_005fcreate" accesskey="p" rel="prev">acc_present_or_create</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fcopyout-_002d_002d-Copy-device-memory-to-host-memory_002e"></a>
<h3 class="section">5.21 <code>acc_copyout</code> &ndash; Copy device memory to host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function copies mapped device memory to host memory which is specified
by host address <var>a</var> for a length <var>len</var> bytes in C/C++.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_copyout(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_copyout(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_copyout(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.21.
</p></dd>
</dl>



<hr>
<a name="acc_005fdelete"></a>
<div class="header">
<p>
Next: <a href="#acc_005fupdate_005fdevice" accesskey="n" rel="next">acc_update_device</a>, Previous: <a href="#acc_005fcopyout" accesskey="p" rel="prev">acc_copyout</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fdelete-_002d_002d-Free-device-memory_002e"></a>
<h3 class="section">5.22 <code>acc_delete</code> &ndash; Free device memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function frees previously allocated device memory specified by
the device address <var>a</var> and the length of <var>len</var> bytes.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_delete(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_delete(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_delete(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.22.
</p></dd>
</dl>



<hr>
<a name="acc_005fupdate_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#acc_005fupdate_005fself" accesskey="n" rel="next">acc_update_self</a>, Previous: <a href="#acc_005fdelete" accesskey="p" rel="prev">acc_delete</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fupdate_005fdevice-_002d_002d-Update-device-memory-from-mapped-host-memory_002e"></a>
<h3 class="section">5.23 <code>acc_update_device</code> &ndash; Update device memory from mapped host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function updates the device copy from the previously mapped host memory.
The host memory is specified with the host address <var>a</var> and a length of
<var>len</var> bytes.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_update_device(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_update_device(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_update_device(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.23.
</p></dd>
</dl>



<hr>
<a name="acc_005fupdate_005fself"></a>
<div class="header">
<p>
Next: <a href="#acc_005fmap_005fdata" accesskey="n" rel="next">acc_map_data</a>, Previous: <a href="#acc_005fupdate_005fdevice" accesskey="p" rel="prev">acc_update_device</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fupdate_005fself-_002d_002d-Update-host-memory-from-mapped-device-memory_002e"></a>
<h3 class="section">5.24 <code>acc_update_self</code> &ndash; Update host memory from mapped device memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function updates the host copy from the previously mapped device memory.
The host memory is specified with the host address <var>a</var> and a length of
<var>len</var> bytes.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_update_self(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_update_self(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine acc_update_self(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.24.
</p></dd>
</dl>



<hr>
<a name="acc_005fmap_005fdata"></a>
<div class="header">
<p>
Next: <a href="#acc_005funmap_005fdata" accesskey="n" rel="next">acc_unmap_data</a>, Previous: <a href="#acc_005fupdate_005fself" accesskey="p" rel="prev">acc_update_self</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fmap_005fdata-_002d_002d-Map-previously-allocated-device-memory-to-host-memory_002e"></a>
<h3 class="section">5.25 <code>acc_map_data</code> &ndash; Map previously allocated device memory to host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function maps previously allocated device and host memory. The device
memory is specified with the device address <var>d</var>. The host memory is
specified with the host address <var>h</var> and a length of <var>len</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_map_data(h_void *h, d_void *d, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.25.
</p></dd>
</dl>



<hr>
<a name="acc_005funmap_005fdata"></a>
<div class="header">
<p>
Next: <a href="#acc_005fdeviceptr" accesskey="n" rel="next">acc_deviceptr</a>, Previous: <a href="#acc_005fmap_005fdata" accesskey="p" rel="prev">acc_map_data</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005funmap_005fdata-_002d_002d-Unmap-device-memory-from-host-memory_002e"></a>
<h3 class="section">5.26 <code>acc_unmap_data</code> &ndash; Unmap device memory from host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function unmaps previously mapped device and host memory. The latter
specified by <var>h</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_unmap_data(h_void *h);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.26.
</p></dd>
</dl>



<hr>
<a name="acc_005fdeviceptr"></a>
<div class="header">
<p>
Next: <a href="#acc_005fhostptr" accesskey="n" rel="next">acc_hostptr</a>, Previous: <a href="#acc_005funmap_005fdata" accesskey="p" rel="prev">acc_unmap_data</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fdeviceptr-_002d_002d-Get-device-pointer-associated-with-specific-host-address_002e"></a>
<h3 class="section">5.27 <code>acc_deviceptr</code> &ndash; Get device pointer associated with specific host address.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns the device address that has been mapped to the
host address specified by <var>h</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_deviceptr(h_void *h);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.27.
</p></dd>
</dl>



<hr>
<a name="acc_005fhostptr"></a>
<div class="header">
<p>
Next: <a href="#acc_005fis_005fpresent" accesskey="n" rel="next">acc_is_present</a>, Previous: <a href="#acc_005fdeviceptr" accesskey="p" rel="prev">acc_deviceptr</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fhostptr-_002d_002d-Get-host-pointer-associated-with-specific-device-address_002e"></a>
<h3 class="section">5.28 <code>acc_hostptr</code> &ndash; Get host pointer associated with specific device address.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns the host address that has been mapped to the
device address specified by <var>d</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_hostptr(d_void *d);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.28.
</p></dd>
</dl>



<hr>
<a name="acc_005fis_005fpresent"></a>
<div class="header">
<p>
Next: <a href="#acc_005fmemcpy_005fto_005fdevice" accesskey="n" rel="next">acc_memcpy_to_device</a>, Previous: <a href="#acc_005fhostptr" accesskey="p" rel="prev">acc_hostptr</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fis_005fpresent-_002d_002d-Indicate-whether-host-variable-_002f-array-is-present-on-device_002e"></a>
<h3 class="section">5.29 <code>acc_is_present</code> &ndash; Indicate whether host variable / array is present on device.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function indicates whether the specified host address in <var>a</var> and a
length of <var>len</var> bytes is present on the device. In C/C++, a non-zero
value is returned to indicate the presence of the mapped memory on the
device. A zero is returned to indicate the memory is not mapped on the
device.
</p>
<p>In Fortran, two (2) forms are supported. In the first form, <var>a</var> specifies
a contiguous array section. The second form <var>a</var> specifies a variable or
array element and <var>len</var> specifies the length in bytes. If the host
memory is mapped to device memory, then a <code>true</code> is returned. Otherwise,
a <code>false</code> is return to indicate the mapped memory is not present.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int acc_is_present(h_void *a, size_t len);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_is_present(a)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical acc_is_present</code></td></tr>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>function acc_is_present(a, len)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>type, dimension(:[,:]...) :: a</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer len</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical acc_is_present</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.29.
</p></dd>
</dl>



<hr>
<a name="acc_005fmemcpy_005fto_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#acc_005fmemcpy_005ffrom_005fdevice" accesskey="n" rel="next">acc_memcpy_from_device</a>, Previous: <a href="#acc_005fis_005fpresent" accesskey="p" rel="prev">acc_is_present</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fmemcpy_005fto_005fdevice-_002d_002d-Copy-host-memory-to-device-memory_002e"></a>
<h3 class="section">5.30 <code>acc_memcpy_to_device</code> &ndash; Copy host memory to device memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function copies host memory specified by host address of <var>src</var> to
device memory specified by the device address <var>dest</var> for a length of
<var>bytes</var> bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_memcpy_to_device(d_void *dest, h_void *src, size_t bytes);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.30.
</p></dd>
</dl>



<hr>
<a name="acc_005fmemcpy_005ffrom_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#acc_005fget_005fcurrent_005fcuda_005fdevice" accesskey="n" rel="next">acc_get_current_cuda_device</a>, Previous: <a href="#acc_005fmemcpy_005fto_005fdevice" accesskey="p" rel="prev">acc_memcpy_to_device</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fmemcpy_005ffrom_005fdevice-_002d_002d-Copy-device-memory-to-host-memory_002e"></a>
<h3 class="section">5.31 <code>acc_memcpy_from_device</code> &ndash; Copy device memory to host memory.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function copies host memory specified by host address of <var>src</var> from
device memory specified by the device address <var>dest</var> for a length of
<var>bytes</var> bytes.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_memcpy_from_device(d_void *dest, h_void *src, size_t bytes);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
3.2.31.
</p></dd>
</dl>



<hr>
<a name="acc_005fget_005fcurrent_005fcuda_005fdevice"></a>
<div class="header">
<p>
Next: <a href="#acc_005fget_005fcurrent_005fcuda_005fcontext" accesskey="n" rel="next">acc_get_current_cuda_context</a>, Previous: <a href="#acc_005fmemcpy_005ffrom_005fdevice" accesskey="p" rel="prev">acc_memcpy_from_device</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fcurrent_005fcuda_005fdevice-_002d_002d-Get-CUDA-device-handle_002e"></a>
<h3 class="section">5.32 <code>acc_get_current_cuda_device</code> &ndash; Get CUDA device handle.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns the CUDA device handle. This handle is the same
as used by the CUDA Runtime or Driver API&rsquo;s.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void *acc_get_current_cuda_device(void);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
A.2.1.1.
</p></dd>
</dl>



<hr>
<a name="acc_005fget_005fcurrent_005fcuda_005fcontext"></a>
<div class="header">
<p>
Next: <a href="#acc_005fget_005fcuda_005fstream" accesskey="n" rel="next">acc_get_cuda_stream</a>, Previous: <a href="#acc_005fget_005fcurrent_005fcuda_005fdevice" accesskey="p" rel="prev">acc_get_current_cuda_device</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fcurrent_005fcuda_005fcontext-_002d_002d-Get-CUDA-context-handle_002e"></a>
<h3 class="section">5.33 <code>acc_get_current_cuda_context</code> &ndash; Get CUDA context handle.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns the CUDA context handle. This handle is the same
as used by the CUDA Runtime or Driver API&rsquo;s.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_get_current_cuda_context(void);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
A.2.1.2.
</p></dd>
</dl>



<hr>
<a name="acc_005fget_005fcuda_005fstream"></a>
<div class="header">
<p>
Next: <a href="#acc_005fset_005fcuda_005fstream" accesskey="n" rel="next">acc_set_cuda_stream</a>, Previous: <a href="#acc_005fget_005fcurrent_005fcuda_005fcontext" accesskey="p" rel="prev">acc_get_current_cuda_context</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fget_005fcuda_005fstream-_002d_002d-Get-CUDA-stream-handle_002e"></a>
<h3 class="section">5.34 <code>acc_get_cuda_stream</code> &ndash; Get CUDA stream handle.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function returns the CUDA stream handle. This handle is the same
as used by the CUDA Runtime or Driver API&rsquo;s.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_get_cuda_stream(void);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
A.2.1.3.
</p></dd>
</dl>



<hr>
<a name="acc_005fset_005fcuda_005fstream"></a>
<div class="header">
<p>
Previous: <a href="#acc_005fget_005fcuda_005fstream" accesskey="p" rel="prev">acc_get_cuda_stream</a>, Up: <a href="#OpenACC-Runtime-Library-Routines" accesskey="u" rel="up">OpenACC Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="acc_005fset_005fcuda_005fstream-_002d_002d-Set-CUDA-stream-handle_002e"></a>
<h3 class="section">5.35 <code>acc_set_cuda_stream</code> &ndash; Set CUDA stream handle.</h3>
<dl compact="compact">
<dt><em>Description</em></dt>
<dd><p>This function associates the stream handle specified by <var>stream</var> with
the asynchronous value specified by <var>async</var>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>acc_set_cuda_stream(int async void *stream);</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
A.2.1.4.
</p></dd>
</dl>




<hr>
<a name="OpenACC-Environment-Variables"></a>
<div class="header">
<p>
Next: <a href="#CUDA-Streams-Usage" accesskey="n" rel="next">CUDA Streams Usage</a>, Previous: <a href="#OpenACC-Runtime-Library-Routines" accesskey="p" rel="prev">OpenACC Runtime Library Routines</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OpenACC-Environment-Variables-1"></a>
<h2 class="chapter">6 OpenACC Environment Variables</h2>

<p>The variables <code>ACC_DEVICE_TYPE</code> and <code>ACC_DEVICE_NUM</code>
are defined by section 4 of the OpenACC specification in version 2.0.
The variable <code>GCC_ACC_NOTIFY</code> is used for diagnostic purposes.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#ACC_005fDEVICE_005fTYPE" accesskey="1">ACC_DEVICE_TYPE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#ACC_005fDEVICE_005fNUM" accesskey="2">ACC_DEVICE_NUM</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GCC_005fACC_005fNOTIFY" accesskey="3">GCC_ACC_NOTIFY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>



<hr>
<a name="ACC_005fDEVICE_005fTYPE"></a>
<div class="header">
<p>
Next: <a href="#ACC_005fDEVICE_005fNUM" accesskey="n" rel="next">ACC_DEVICE_NUM</a>, Up: <a href="#OpenACC-Environment-Variables" accesskey="u" rel="up">OpenACC Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="ACC_005fDEVICE_005fTYPE-1"></a>
<h3 class="section">6.1 <code>ACC_DEVICE_TYPE</code></h3>
<dl compact="compact">
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
4.1.
</p></dd>
</dl>



<hr>
<a name="ACC_005fDEVICE_005fNUM"></a>
<div class="header">
<p>
Next: <a href="#GCC_005fACC_005fNOTIFY" accesskey="n" rel="next">GCC_ACC_NOTIFY</a>, Previous: <a href="#ACC_005fDEVICE_005fTYPE" accesskey="p" rel="prev">ACC_DEVICE_TYPE</a>, Up: <a href="#OpenACC-Environment-Variables" accesskey="u" rel="up">OpenACC Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="ACC_005fDEVICE_005fNUM-1"></a>
<h3 class="section">6.2 <code>ACC_DEVICE_NUM</code></h3>
<dl compact="compact">
<dt><em>Reference</em>:</dt>
<dd><p><a href="https://www.openacc.org">OpenACC specification v2.0</a>, section
4.2.
</p></dd>
</dl>



<hr>
<a name="GCC_005fACC_005fNOTIFY"></a>
<div class="header">
<p>
Previous: <a href="#ACC_005fDEVICE_005fNUM" accesskey="p" rel="prev">ACC_DEVICE_NUM</a>, Up: <a href="#OpenACC-Environment-Variables" accesskey="u" rel="up">OpenACC Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GCC_005fACC_005fNOTIFY-1"></a>
<h3 class="section">6.3 <code>GCC_ACC_NOTIFY</code></h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Print debug information pertaining to the accelerator.
</p></dd>
</dl>




<hr>
<a name="CUDA-Streams-Usage"></a>
<div class="header">
<p>
Next: <a href="#OpenACC-Library-Interoperability" accesskey="n" rel="next">OpenACC Library Interoperability</a>, Previous: <a href="#OpenACC-Environment-Variables" accesskey="p" rel="prev">OpenACC Environment Variables</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="CUDA-Streams-Usage-1"></a>
<h2 class="chapter">7 CUDA Streams Usage</h2>

<p>This applies to the <code>nvptx</code> plugin only.
</p>
<p>The library provides elements that perform asynchronous movement of
data and asynchronous operation of computing constructs.  This
asynchronous functionality is implemented by making use of CUDA
streams<a name="DOCF1" href="#FOOT1"><sup>1</sup></a>.
</p>
<p>The primary means by that the asychronous functionality is accessed
is through the use of those OpenACC directives which make use of the
<code>async</code> and <code>wait</code> clauses.  When the <code>async</code> clause is
first used with a directive, it creates a CUDA stream.  If an
<code>async-argument</code> is used with the <code>async</code> clause, then the
stream is associated with the specified <code>async-argument</code>.
</p>
<p>Following the creation of an association between a CUDA stream and the
<code>async-argument</code> of an <code>async</code> clause, both the <code>wait</code>
clause and the <code>wait</code> directive can be used.  When either the
clause or directive is used after stream creation, it creates a
rendezvous point whereby execution waits until all operations
associated with the <code>async-argument</code>, that is, stream, have
completed.
</p>
<p>Normally, the management of the streams that are created as a result of
using the <code>async</code> clause, is done without any intervention by the
caller.  This implies the association between the <code>async-argument</code>
and the CUDA stream will be maintained for the lifetime of the program.
However, this association can be changed through the use of the library
function <code>acc_set_cuda_stream</code>.  When the function
<code>acc_set_cuda_stream</code> is called, the CUDA stream that was
originally associated with the <code>async</code> clause will be destroyed.
Caution should be taken when changing the association as subsequent
references to the <code>async-argument</code> refer to a different
CUDA stream.
</p>



<hr>
<a name="OpenACC-Library-Interoperability"></a>
<div class="header">
<p>
Next: <a href="#The-libgomp-ABI" accesskey="n" rel="next">The libgomp ABI</a>, Previous: <a href="#CUDA-Streams-Usage" accesskey="p" rel="prev">CUDA Streams Usage</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OpenACC-Library-Interoperability-1"></a>
<h2 class="chapter">8 OpenACC Library Interoperability</h2>

<a name="Introduction-1"></a>
<h3 class="section">8.1 Introduction</h3>

<p>The OpenACC library uses the CUDA Driver API, and may interact with
programs that use the Runtime library directly, or another library
based on the Runtime library, e.g., CUBLAS<a name="DOCF2" href="#FOOT2"><sup>2</sup></a>.
This chapter describes the use cases and what changes are
required in order to use both the OpenACC library and the CUBLAS and Runtime
libraries within a program.
</p>
<a name="First-invocation_003a-NVIDIA-CUBLAS-library-API"></a>
<h3 class="section">8.2 First invocation: NVIDIA CUBLAS library API</h3>

<p>In this first use case (see below), a function in the CUBLAS library is called
prior to any of the functions in the OpenACC library. More specifically, the
function <code>cublasCreate()</code>.
</p>
<p>When invoked, the function initializes the library and allocates the
hardware resources on the host and the device on behalf of the caller. Once
the initialization and allocation has completed, a handle is returned to the
caller. The OpenACC library also requires initialization and allocation of
hardware resources. Since the CUBLAS library has already allocated the
hardware resources for the device, all that is left to do is to initialize
the OpenACC library and acquire the hardware resources on the host.
</p>
<p>Prior to calling the OpenACC function that initializes the library and
allocate the host hardware resources, you need to acquire the device number
that was allocated during the call to <code>cublasCreate()</code>. The invoking of the
runtime library function <code>cudaGetDevice()</code> accomplishes this. Once
acquired, the device number is passed along with the device type as
parameters to the OpenACC library function <code>acc_set_device_num()</code>.
</p>
<p>Once the call to <code>acc_set_device_num()</code> has completed, the OpenACC
library uses the  context that was created during the call to
<code>cublasCreate()</code>. In other words, both libraries will be sharing the
same context.
</p>
<div class="smallexample">
<pre class="smallexample">    /* Create the handle */
    s = cublasCreate(&amp;h);
    if (s != CUBLAS_STATUS_SUCCESS)
    {
        fprintf(stderr, &quot;cublasCreate failed %d\n&quot;, s);
        exit(EXIT_FAILURE);
    }

    /* Get the device number */
    e = cudaGetDevice(&amp;dev);
    if (e != cudaSuccess)
    {
        fprintf(stderr, &quot;cudaGetDevice failed %d\n&quot;, e);
        exit(EXIT_FAILURE);
    }

    /* Initialize OpenACC library and use device 'dev' */
    acc_set_device_num(dev, acc_device_nvidia);

</pre></div>
<div align="center">Use Case 1
</div>
<a name="First-invocation_003a-OpenACC-library-API"></a>
<h3 class="section">8.3 First invocation: OpenACC library API</h3>

<p>In this second use case (see below), a function in the OpenACC library is
called prior to any of the functions in the CUBLAS library. More specificially,
the function <code>acc_set_device_num()</code>.
</p>
<p>In the use case presented here, the function <code>acc_set_device_num()</code>
is used to both initialize the OpenACC library and allocate the hardware
resources on the host and the device. In the call to the function, the
call parameters specify which device to use and what device
type to use, i.e., <code>acc_device_nvidia</code>. It should be noted that this
is but one method to initialize the OpenACC library and allocate the
appropriate hardware resources. Other methods are available through the
use of environment variables and these will be discussed in the next section.
</p>
<p>Once the call to <code>acc_set_device_num()</code> has completed, other OpenACC
functions can be called as seen with multiple calls being made to
<code>acc_copyin()</code>. In addition, calls can be made to functions in the
CUBLAS library. In the use case a call to <code>cublasCreate()</code> is made
subsequent to the calls to <code>acc_copyin()</code>.
As seen in the previous use case, a call to <code>cublasCreate()</code>
initializes the CUBLAS library and allocates the hardware resources on the
host and the device.  However, since the device has already been allocated,
<code>cublasCreate()</code> will only initialize the CUBLAS library and allocate
the appropriate hardware resources on the host. The context that was created
as part of the OpenACC initialization is shared with the CUBLAS library,
similarly to the first use case.
</p>
<div class="smallexample">
<pre class="smallexample">    dev = 0;

    acc_set_device_num(dev, acc_device_nvidia);

    /* Copy the first set to the device */
    d_X = acc_copyin(&amp;h_X[0], N * sizeof (float));
    if (d_X == NULL)
    { 
        fprintf(stderr, &quot;copyin error h_X\n&quot;);
        exit(EXIT_FAILURE);
    }

    /* Copy the second set to the device */
    d_Y = acc_copyin(&amp;h_Y1[0], N * sizeof (float));
    if (d_Y == NULL)
    { 
        fprintf(stderr, &quot;copyin error h_Y1\n&quot;);
        exit(EXIT_FAILURE);
    }

    /* Create the handle */
    s = cublasCreate(&amp;h);
    if (s != CUBLAS_STATUS_SUCCESS)
    {
        fprintf(stderr, &quot;cublasCreate failed %d\n&quot;, s);
        exit(EXIT_FAILURE);
    }

    /* Perform saxpy using CUBLAS library function */
    s = cublasSaxpy(h, N, &amp;alpha, d_X, 1, d_Y, 1);
    if (s != CUBLAS_STATUS_SUCCESS)
    {
        fprintf(stderr, &quot;cublasSaxpy failed %d\n&quot;, s);
        exit(EXIT_FAILURE);
    }

    /* Copy the results from the device */
    acc_memcpy_from_device(&amp;h_Y1[0], d_Y, N * sizeof (float));

</pre></div>
<div align="center">Use Case 2
</div>
<a name="OpenACC-library-and-environment-variables"></a>
<h3 class="section">8.4 OpenACC library and environment variables</h3>

<p>There are two environment variables associated with the OpenACC library
that may be used to control the device type and device number:
<code>ACC_DEVICE_TYPE</code> and <code>ACC_DEVICE_NUM</code>, respecively. These two
environement variables can be used as an alternative to calling
<code>acc_set_device_num()</code>. As seen in the second use case, the device
type and device number were specified using <code>acc_set_device_num()</code>.
If however, the aforementioned environment variables were set, then the
call to <code>acc_set_device_num()</code> would not be required.
</p>

<p>The use of the environment variables is only relevant when an OpenACC function
is called prior to a call to <code>cudaCreate()</code>. If <code>cudaCreate()</code>
is called prior to a call to an OpenACC function, then you must call
<code>acc_set_device_num()</code><a name="DOCF3" href="#FOOT3"><sup>3</sup></a>
</p>



<hr>
<a name="The-libgomp-ABI"></a>
<div class="header">
<p>
Next: <a href="#Reporting-Bugs" accesskey="n" rel="next">Reporting Bugs</a>, Previous: <a href="#OpenACC-Library-Interoperability" accesskey="p" rel="prev">OpenACC Library Interoperability</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-libgomp-ABI-1"></a>
<h2 class="chapter">9 The libgomp ABI</h2>

<p>The following sections present notes on the external ABI as 
presented by libgomp.  Only maintainers should need them.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Implementing-MASTER-construct" accesskey="1">Implementing MASTER construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-CRITICAL-construct" accesskey="2">Implementing CRITICAL construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-ATOMIC-construct" accesskey="3">Implementing ATOMIC construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FLUSH-construct" accesskey="4">Implementing FLUSH construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-BARRIER-construct" accesskey="5">Implementing BARRIER construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-THREADPRIVATE-construct" accesskey="6">Implementing THREADPRIVATE construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-PRIVATE-clause" accesskey="7">Implementing PRIVATE clause</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="8">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-REDUCTION-clause" accesskey="9">Implementing REDUCTION clause</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-PARALLEL-construct">Implementing PARALLEL construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FOR-construct">Implementing FOR construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-ORDERED-construct">Implementing ORDERED construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-SECTIONS-construct">Implementing SECTIONS construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-SINGLE-construct">Implementing SINGLE construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-OpenACC_0027s-PARALLEL-construct">Implementing OpenACC's PARALLEL construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>


<hr>
<a name="Implementing-MASTER-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-CRITICAL-construct" accesskey="n" rel="next">Implementing CRITICAL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-MASTER-construct-1"></a>
<h3 class="section">9.1 Implementing MASTER construct</h3>

<div class="smallexample">
<pre class="smallexample">if (omp_get_thread_num () == 0)
  block
</pre></div>

<p>Alternately, we generate two copies of the parallel subfunction
and only include this in the version run by the master thread.
Surely this is not worthwhile though...
</p>


<hr>
<a name="Implementing-CRITICAL-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-ATOMIC-construct" accesskey="n" rel="next">Implementing ATOMIC construct</a>, Previous: <a href="#Implementing-MASTER-construct" accesskey="p" rel="prev">Implementing MASTER construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-CRITICAL-construct-1"></a>
<h3 class="section">9.2 Implementing CRITICAL construct</h3>

<p>Without a specified name,
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_critical_start (void);
  void GOMP_critical_end (void);
</pre></div>

<p>so that we don&rsquo;t get COPY relocations from libgomp to the main
application.
</p>
<p>With a specified name, use omp_set_lock and omp_unset_lock with
name being transformed into a variable declared like
</p>
<div class="smallexample">
<pre class="smallexample">  omp_lock_t gomp_critical_user_&lt;name&gt; __attribute__((common))
</pre></div>

<p>Ideally the ABI would specify that all zero is a valid unlocked
state, and so we wouldn&rsquo;t need to initialize this at
startup.
</p>


<hr>
<a name="Implementing-ATOMIC-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FLUSH-construct" accesskey="n" rel="next">Implementing FLUSH construct</a>, Previous: <a href="#Implementing-CRITICAL-construct" accesskey="p" rel="prev">Implementing CRITICAL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-ATOMIC-construct-1"></a>
<h3 class="section">9.3 Implementing ATOMIC construct</h3>

<p>The target should implement the <code>__sync</code> builtins.
</p>
<p>Failing that we could add
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_atomic_enter (void)
  void GOMP_atomic_exit (void)
</pre></div>

<p>which reuses the regular lock code, but with yet another lock
object private to the library.
</p>


<hr>
<a name="Implementing-FLUSH-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-BARRIER-construct" accesskey="n" rel="next">Implementing BARRIER construct</a>, Previous: <a href="#Implementing-ATOMIC-construct" accesskey="p" rel="prev">Implementing ATOMIC construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FLUSH-construct-1"></a>
<h3 class="section">9.4 Implementing FLUSH construct</h3>

<p>Expands to the <code>__sync_synchronize</code> builtin.
</p>


<hr>
<a name="Implementing-BARRIER-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-THREADPRIVATE-construct" accesskey="n" rel="next">Implementing THREADPRIVATE construct</a>, Previous: <a href="#Implementing-FLUSH-construct" accesskey="p" rel="prev">Implementing FLUSH construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-BARRIER-construct-1"></a>
<h3 class="section">9.5 Implementing BARRIER construct</h3>

<div class="smallexample">
<pre class="smallexample">  void GOMP_barrier (void)
</pre></div>


<hr>
<a name="Implementing-THREADPRIVATE-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-PRIVATE-clause" accesskey="n" rel="next">Implementing PRIVATE clause</a>, Previous: <a href="#Implementing-BARRIER-construct" accesskey="p" rel="prev">Implementing BARRIER construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-THREADPRIVATE-construct-1"></a>
<h3 class="section">9.6 Implementing THREADPRIVATE construct</h3>

<p>In _most_ cases we can map this directly to <code>__thread</code>.  Except
that OMP allows constructors for C++ objects.  We can either
refuse to support this (how often is it used?) or we can 
implement something akin to .ctors.
</p>
<p>Even more ideally, this ctor feature is handled by extensions
to the main pthreads library.  Failing that, we can have a set
of entry points to register ctor functions to be called.
</p>


<hr>
<a name="Implementing-PRIVATE-clause"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="n" rel="next">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>, Previous: <a href="#Implementing-THREADPRIVATE-construct" accesskey="p" rel="prev">Implementing THREADPRIVATE construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-PRIVATE-clause-1"></a>
<h3 class="section">9.7 Implementing PRIVATE clause</h3>

<p>In association with a PARALLEL, or within the lexical extent
of a PARALLEL block, the variable becomes a local variable in
the parallel subfunction.
</p>
<p>In association with FOR or SECTIONS blocks, create a new
automatic variable within the current function.  This preserves
the semantic of new variable creation.
</p>


<hr>
<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses"></a>
<div class="header">
<p>
Next: <a href="#Implementing-REDUCTION-clause" accesskey="n" rel="next">Implementing REDUCTION clause</a>, Previous: <a href="#Implementing-PRIVATE-clause" accesskey="p" rel="prev">Implementing PRIVATE clause</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1"></a>
<h3 class="section">9.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</h3>

<p>This seems simple enough for PARALLEL blocks.  Create a private 
struct for communicating between the parent and subfunction.
In the parent, copy in values for scalar and &quot;small&quot; structs;
copy in addresses for others TREE_ADDRESSABLE types.  In the 
subfunction, copy the value into the local variable.
</p>
<p>It is not clear what to do with bare FOR or SECTION blocks.
The only thing I can figure is that we do something like:
</p>
<div class="smallexample">
<pre class="smallexample">#pragma omp for firstprivate(x) lastprivate(y)
for (int i = 0; i &lt; n; ++i)
  body;
</pre></div>

<p>which becomes
</p>
<div class="smallexample">
<pre class="smallexample">{
  int x = x, y;

  // for stuff

  if (i == n)
    y = y;
}
</pre></div>

<p>where the &quot;x=x&quot; and &quot;y=y&quot; assignments actually have different
uids for the two variables, i.e. not something you could write
directly in C.  Presumably this only makes sense if the &quot;outer&quot;
x and y are global variables.
</p>
<p>COPYPRIVATE would work the same way, except the structure 
broadcast would have to happen via SINGLE machinery instead.
</p>


<hr>
<a name="Implementing-REDUCTION-clause"></a>
<div class="header">
<p>
Next: <a href="#Implementing-PARALLEL-construct" accesskey="n" rel="next">Implementing PARALLEL construct</a>, Previous: <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="p" rel="prev">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-REDUCTION-clause-1"></a>
<h3 class="section">9.9 Implementing REDUCTION clause</h3>

<p>The private struct mentioned in the previous section should have 
a pointer to an array of the type of the variable, indexed by the 
thread&rsquo;s <var>team_id</var>.  The thread stores its final value into the 
array, and after the barrier, the master thread iterates over the
array to collect the values.
</p>

<hr>
<a name="Implementing-PARALLEL-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FOR-construct" accesskey="n" rel="next">Implementing FOR construct</a>, Previous: <a href="#Implementing-REDUCTION-clause" accesskey="p" rel="prev">Implementing REDUCTION clause</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-PARALLEL-construct-1"></a>
<h3 class="section">9.10 Implementing PARALLEL construct</h3>

<div class="smallexample">
<pre class="smallexample">  #pragma omp parallel
  {
    body;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  void subfunction (void *data)
  {
    use data;
    body;
  }

  setup data;
  GOMP_parallel_start (subfunction, &amp;data, num_threads);
  subfunction (&amp;data);
  GOMP_parallel_end ();
</pre></div>

<div class="smallexample">
<pre class="smallexample">  void GOMP_parallel_start (void (*fn)(void *), void *data, unsigned num_threads)
</pre></div>

<p>The <var>FN</var> argument is the subfunction to be run in parallel.
</p>
<p>The <var>DATA</var> argument is a pointer to a structure used to 
communicate data in and out of the subfunction, as discussed
above with respect to FIRSTPRIVATE et al.
</p>
<p>The <var>NUM_THREADS</var> argument is 1 if an IF clause is present
and false, or the value of the NUM_THREADS clause, if
present, or 0.
</p>
<p>The function needs to create the appropriate number of
threads and/or launch them from the dock.  It needs to
create the team structure and assign team ids.
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_parallel_end (void)
</pre></div>

<p>Tears down the team and returns us to the previous <code>omp_in_parallel()</code> state.
</p>


<hr>
<a name="Implementing-FOR-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-ORDERED-construct" accesskey="n" rel="next">Implementing ORDERED construct</a>, Previous: <a href="#Implementing-PARALLEL-construct" accesskey="p" rel="prev">Implementing PARALLEL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FOR-construct-1"></a>
<h3 class="section">9.11 Implementing FOR construct</h3>

<div class="smallexample">
<pre class="smallexample">  #pragma omp parallel for
  for (i = lb; i &lt;= ub; i++)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  void subfunction (void *data)
  {
    long _s0, _e0;
    while (GOMP_loop_static_next (&amp;_s0, &amp;_e0))
    {
      long _e1 = _e0, i;
      for (i = _s0; i &lt; _e1; i++)
        body;
    }
    GOMP_loop_end_nowait ();
  }

  GOMP_parallel_loop_static (subfunction, NULL, 0, lb, ub+1, 1, 0);
  subfunction (NULL);
  GOMP_parallel_end ();
</pre></div>

<div class="smallexample">
<pre class="smallexample">  #pragma omp for schedule(runtime)
  for (i = 0; i &lt; n; i++)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  {
    long i, _s0, _e0;
    if (GOMP_loop_runtime_start (0, n, 1, &amp;_s0, &amp;_e0))
      do {
        long _e1 = _e0;
        for (i = _s0, i &lt; _e0; i++)
          body;
      } while (GOMP_loop_runtime_next (&amp;_s0, _&amp;e0));
    GOMP_loop_end ();
  }
</pre></div>

<p>Note that while it looks like there is trickiness to propagating
a non-constant STEP, there isn&rsquo;t really.  We&rsquo;re explicitly allowed
to evaluate it as many times as we want, and any variables involved
should automatically be handled as PRIVATE or SHARED like any other
variables.  So the expression should remain evaluable in the 
subfunction.  We can also pull it into a local variable if we like,
but since its supposed to remain unchanged, we can also not if we like.
</p>
<p>If we have SCHEDULE(STATIC), and no ORDERED, then we ought to be
able to get away with no work-sharing context at all, since we can
simply perform the arithmetic directly in each thread to divide up
the iterations.  Which would mean that we wouldn&rsquo;t need to call any
of these routines.
</p>
<p>There are separate routines for handling loops with an ORDERED
clause.  Bookkeeping for that is non-trivial...
</p>


<hr>
<a name="Implementing-ORDERED-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-SECTIONS-construct" accesskey="n" rel="next">Implementing SECTIONS construct</a>, Previous: <a href="#Implementing-FOR-construct" accesskey="p" rel="prev">Implementing FOR construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-ORDERED-construct-1"></a>
<h3 class="section">9.12 Implementing ORDERED construct</h3>

<div class="smallexample">
<pre class="smallexample">  void GOMP_ordered_start (void)
  void GOMP_ordered_end (void)
</pre></div>



<hr>
<a name="Implementing-SECTIONS-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-SINGLE-construct" accesskey="n" rel="next">Implementing SINGLE construct</a>, Previous: <a href="#Implementing-ORDERED-construct" accesskey="p" rel="prev">Implementing ORDERED construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-SECTIONS-construct-1"></a>
<h3 class="section">9.13 Implementing SECTIONS construct</h3>

<p>A block as 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp sections
  {
    #pragma omp section
    stmt1;
    #pragma omp section
    stmt2;
    #pragma omp section
    stmt3;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  for (i = GOMP_sections_start (3); i != 0; i = GOMP_sections_next ())
    switch (i)
      {
      case 1:
        stmt1;
        break;
      case 2:
        stmt2;
        break;
      case 3:
        stmt3;
        break;
      }
  GOMP_barrier ();
</pre></div>


<hr>
<a name="Implementing-SINGLE-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-OpenACC_0027s-PARALLEL-construct" accesskey="n" rel="next">Implementing OpenACC's PARALLEL construct</a>, Previous: <a href="#Implementing-SECTIONS-construct" accesskey="p" rel="prev">Implementing SECTIONS construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-SINGLE-construct-1"></a>
<h3 class="section">9.14 Implementing SINGLE construct</h3>

<p>A block like 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp single
  {
    body;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  if (GOMP_single_start ())
    body;
  GOMP_barrier ();
</pre></div>

<p>while 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp single copyprivate(x)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  datap = GOMP_single_copy_start ();
  if (datap == NULL)
    {
      body;
      data.x = x;
      GOMP_single_copy_end (&amp;data);
    }
  else
    x = datap-&gt;x;
  GOMP_barrier ();
</pre></div>



<hr>
<a name="Implementing-OpenACC_0027s-PARALLEL-construct"></a>
<div class="header">
<p>
Previous: <a href="#Implementing-SINGLE-construct" accesskey="p" rel="prev">Implementing SINGLE construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-OpenACC_0027s-PARALLEL-construct-1"></a>
<h3 class="section">9.15 Implementing OpenACC&rsquo;s PARALLEL construct</h3>

<div class="smallexample">
<pre class="smallexample">  void GOACC_parallel ()
</pre></div>




<hr>
<a name="Reporting-Bugs"></a>
<div class="header">
<p>
Next: <a href="#Copying" accesskey="n" rel="next">Copying</a>, Previous: <a href="#The-libgomp-ABI" accesskey="p" rel="prev">The libgomp ABI</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Reporting-Bugs-1"></a>
<h2 class="chapter">10 Reporting Bugs</h2>

<p>Bugs in the GNU Offloading and Multi Processing Runtime Library should
be reported via <a href="http://gcc.gnu.org/bugzilla/">Bugzilla</a>.  Please add
&quot;openacc&quot;, or &quot;openmp&quot;, or both to the keywords field in the bug
report, as appropriate.
</p>



<hr>
<a name="Copying"></a>
<div class="header">
<p>
Next: <a href="#GNU-Free-Documentation-License" accesskey="n" rel="next">GNU Free Documentation License</a>, Previous: <a href="#Reporting-Bugs" accesskey="p" rel="prev">Reporting Bugs</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GNU-General-Public-License"></a>
<h2 class="unnumbered">GNU General Public License</h2>
<div align="center">Version 3, 29 June 2007
</div>

<div class="display">
<pre class="display">Copyright &copy; 2007 Free Software Foundation, Inc. <a href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
</pre></div>

<a name="Preamble"></a>
<h3 class="heading">Preamble</h3>

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<a name="TERMS-AND-CONDITIONS"></a>
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excuse you from the conditions of this License.  If you cannot convey
a covered work so as to satisfy simultaneously your obligations under
this License and any other pertinent obligations, then as a
consequence you may not convey it at all.  For example, if you agree
to terms that obligate you to collect a royalty for further conveying
from those to whom you convey the Program, the only way you could
satisfy both those terms and this License would be to refrain entirely
from conveying the Program.
</p>
</li><li> Use with the GNU Affero General Public License.

<p>Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work.  The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.
</p>
</li><li> Revised Versions of this License.

<p>The Free Software Foundation may publish revised and/or new versions
of the GNU General Public License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
</p>
<p>Each version is given a distinguishing version number.  If the Program
specifies that a certain numbered version of the GNU General Public
License &ldquo;or any later version&rdquo; applies to it, you have the option of
following the terms and conditions either of that numbered version or
of any later version published by the Free Software Foundation.  If
the Program does not specify a version number of the GNU General
Public License, you may choose any version ever published by the Free
Software Foundation.
</p>
<p>If the Program specifies that a proxy can decide which future versions
of the GNU General Public License can be used, that proxy&rsquo;s public
statement of acceptance of a version permanently authorizes you to
choose that version for the Program.
</p>
<p>Later license versions may give you additional or different
permissions.  However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.
</p>
</li><li> Disclaimer of Warranty.

<p>THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM &ldquo;AS IS&rdquo; WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND
PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
CORRECTION.
</p>
</li><li> Limitation of Liability.

<p>IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR
CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT
NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM
TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER
PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
</p>
</li><li> Interpretation of Sections 15 and 16.

<p>If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.
</p>
</li></ol>

<a name="END-OF-TERMS-AND-CONDITIONS"></a>
<h3 class="heading">END OF TERMS AND CONDITIONS</h3>

<a name="How-to-Apply-These-Terms-to-Your-New-Programs"></a>
<h3 class="heading">How to Apply These Terms to Your New Programs</h3>

<p>If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
</p>
<p>To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the &ldquo;copyright&rdquo; line and a pointer to where the full notice is found.
</p>
<div class="smallexample">
<pre class="smallexample"><var>one line to give the program's name and a brief idea of what it does.</var>  
Copyright (C) <var>year</var> <var>name of author</var>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <a href="http://www.gnu.org/licenses/">http://www.gnu.org/licenses/</a>.
</pre></div>

<p>Also add information on how to contact you by electronic and paper mail.
</p>
<p>If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
</p>
<div class="smallexample">
<pre class="smallexample"><var>program</var> Copyright (C) <var>year</var> <var>name of author</var> 
This program comes with ABSOLUTELY NO WARRANTY; for details type &lsquo;<samp>show w</samp>&rsquo;.
This is free software, and you are welcome to redistribute it
under certain conditions; type &lsquo;<samp>show c</samp>&rsquo; for details.
</pre></div>

<p>The hypothetical commands &lsquo;<samp>show w</samp>&rsquo; and &lsquo;<samp>show c</samp>&rsquo; should show
the appropriate parts of the General Public License.  Of course, your
program&rsquo;s commands might be different; for a GUI interface, you would
use an &ldquo;about box&rdquo;.
</p>
<p>You should also get your employer (if you work as a programmer) or school,
if any, to sign a &ldquo;copyright disclaimer&rdquo; for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<a href="http://www.gnu.org/licenses/">http://www.gnu.org/licenses/</a>.
</p>
<p>The GNU General Public License does not permit incorporating your
program into proprietary programs.  If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library.  If this is what you want to do, use
the GNU Lesser General Public License instead of this License.  But
first, please read <a href="http://www.gnu.org/philosophy/why-not-lgpl.html">http://www.gnu.org/philosophy/why-not-lgpl.html</a>.
</p>



<hr>
<a name="GNU-Free-Documentation-License"></a>
<div class="header">
<p>
Next: <a href="#Funding" accesskey="n" rel="next">Funding</a>, Previous: <a href="#Copying" accesskey="p" rel="prev">Copying</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GNU-Free-Documentation-License-1"></a>
<h2 class="unnumbered">GNU Free Documentation License</h2>

<a name="index-FDL_002c-GNU-Free-Documentation-License"></a>
<div align="center">Version 1.3, 3 November 2008
</div>
<div class="display">
<pre class="display">Copyright &copy; 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<ol start="0">
<li> PREAMBLE

<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em>free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of &ldquo;copyleft&rdquo;, which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS

<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The &ldquo;Document&rdquo;, below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as &ldquo;you&rdquo;.  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A &ldquo;Modified Version&rdquo; of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A &ldquo;Secondary Section&rdquo; is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document&rsquo;s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The &ldquo;Invariant Sections&rdquo; are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The &ldquo;Cover Texts&rdquo; are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A &ldquo;Transparent&rdquo; copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not &ldquo;Transparent&rdquo; is called &ldquo;Opaque&rdquo;.
</p>
<p>Examples of suitable formats for Transparent copies include plain
<small>ASCII</small> without markup, Texinfo input format, LaTeX input
format, <acronym>SGML</acronym> or <acronym>XML</acronym> using a publicly available
<acronym>DTD</acronym>, and standard-conforming simple <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> designed for human modification.  Examples
of transparent image formats include <acronym>PNG</acronym>, <acronym>XCF</acronym> and
<acronym>JPG</acronym>.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <acronym>SGML</acronym> or
<acronym>XML</acronym> for which the <acronym>DTD</acronym> and/or processing tools are
not generally available, and the machine-generated <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> produced by some word processors for
output purposes only.
</p>
<p>The &ldquo;Title Page&rdquo; means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, &ldquo;Title Page&rdquo; means
the text near the most prominent appearance of the work&rsquo;s title,
preceding the beginning of the body of the text.
</p>
<p>The &ldquo;publisher&rdquo; means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section &ldquo;Entitled XYZ&rdquo; means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, &ldquo;Endorsements&rdquo;, or &ldquo;History&rdquo;.)  To &ldquo;Preserve the Title&rdquo;
of such a section when you modify the Document means that it remains a
section &ldquo;Entitled XYZ&rdquo; according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING

<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY

<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document&rsquo;s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS

<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</p>
<ol type="A" start="1">
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.

</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.

</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.

</li><li> Preserve all the copyright notices of the Document.

</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.

</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document&rsquo;s license notice.

</li><li> Include an unaltered copy of this License.

</li><li> Preserve the section Entitled &ldquo;History&rdquo;, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled &ldquo;History&rdquo; in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.

</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the &ldquo;History&rdquo; section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.

</li><li> For any section Entitled &ldquo;Acknowledgements&rdquo; or &ldquo;Dedications&rdquo;, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.

</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.

</li><li> Delete any section Entitled &ldquo;Endorsements&rdquo;.  Such a section
may not be included in the Modified Version.

</li><li> Do not retitle any existing section to be Entitled &ldquo;Endorsements&rdquo; or
to conflict in title with any Invariant Section.

</li><li> Preserve any Warranty Disclaimers.
</li></ol>

<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version&rsquo;s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled &ldquo;Endorsements&rdquo;, provided it contains
nothing but endorsements of your Modified Version by various
parties&mdash;for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</p>
<p>You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</p>
<p>The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</p>
</li><li> COMBINING DOCUMENTS

<p>You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</p>
<p>The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</p>
<p>In the combination, you must combine any sections Entitled &ldquo;History&rdquo;
in the various original documents, forming one section Entitled
&ldquo;History&rdquo;; likewise combine any sections Entitled &ldquo;Acknowledgements&rdquo;,
and any sections Entitled &ldquo;Dedications&rdquo;.  You must delete all
sections Entitled &ldquo;Endorsements.&rdquo;
</p>
</li><li> COLLECTIONS OF DOCUMENTS

<p>You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</p>
<p>You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</p>
</li><li> AGGREGATION WITH INDEPENDENT WORKS

<p>A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an &ldquo;aggregate&rdquo; if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation&rsquo;s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</p>
<p>If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document&rsquo;s Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</p>
</li><li> TRANSLATION

<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, or &ldquo;History&rdquo;, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li> TERMINATION

<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li> FUTURE REVISIONS OF THIS LICENSE

<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
<a href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
</p>
<p>Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License &ldquo;or any later version&rdquo; applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.  If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy&rsquo;s public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</p>
</li><li> RELICENSING

<p>&ldquo;Massive Multiauthor Collaboration Site&rdquo; (or &ldquo;MMC Site&rdquo;) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.  A
public wiki that anybody can edit is an example of such a server.  A
&ldquo;Massive Multiauthor Collaboration&rdquo; (or &ldquo;MMC&rdquo;) contained in the
site means any set of copyrightable works thus published on the MMC
site.
</p>
<p>&ldquo;CC-BY-SA&rdquo; means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>&ldquo;Incorporate&rdquo; means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is &ldquo;eligible for relicensing&rdquo; if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>

<a name="ADDENDUM_003a-How-to-use-this-License-for-your-documents"></a>
<h3 class="unnumberedsec">ADDENDUM: How to use this License for your documents</h3>

<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="smallexample">
<pre class="smallexample">  Copyright (C)  <var>year</var>  <var>your name</var>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</pre></div>

<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the &ldquo;with...Texts.&rdquo; line with this:
</p>
<div class="smallexample">
<pre class="smallexample">    with the Invariant Sections being <var>list their titles</var>, with
    the Front-Cover Texts being <var>list</var>, and with the Back-Cover Texts
    being <var>list</var>.
</pre></div>

<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>





<hr>
<a name="Funding"></a>
<div class="header">
<p>
Next: <a href="#Library-Index" accesskey="n" rel="next">Library Index</a>, Previous: <a href="#GNU-Free-Documentation-License" accesskey="p" rel="prev">GNU Free Documentation License</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Funding-Free-Software"></a>
<h2 class="unnumbered">Funding Free Software</h2>

<p>If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development.  The most effective approach known is to encourage
commercial redistributors to donate.
</p>
<p>Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers&mdash;the Free Software Foundation, and others.
</p>
<p>The way to convince distributors to do this is to demand it and expect
it from them.  So when you compare distributors, judge them partly by
how much they give to free software development.  Show distributors
they must compete to be the one who gives the most.
</p>
<p>To make this approach work, you must insist on numbers that you can
compare, such as, &ldquo;We will donate ten dollars to the Frobnitz project
for each disk sold.&rdquo;  Don&rsquo;t be satisfied with a vague promise, such as
&ldquo;A portion of the profits are donated,&rdquo; since it doesn&rsquo;t give a basis
for comparison.
</p>
<p>Even a precise fraction &ldquo;of the profits from this disk&rdquo; is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.
If the price you pay is $50, ten percent of the profit is probably
less than a dollar; it might be a few cents, or nothing at all.
</p>
<p>Some redistributors do development work themselves.  This is useful too;
but to keep everyone honest, you need to inquire how much they do, and
what kind.  Some kinds of development make much more long-term
difference than others.  For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much.  Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU Compiler Collection contribute more;
major new features or packages contribute the most.
</p>
<p>By establishing the idea that supporting further development is &ldquo;the
proper thing to do&rdquo; when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.
</p>
<div class="display">
<pre class="display">Copyright &copy; 1994 Free Software Foundation, Inc.
Verbatim copying and redistribution of this section is permitted
without royalty; alteration is not permitted.
</pre></div>


<hr>
<a name="Library-Index"></a>
<div class="header">
<p>
Previous: <a href="#Funding" accesskey="p" rel="prev">Funding</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Library-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Library-Index-1"></a>
<h2 class="unnumbered">Library Index</h2>

<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Library-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter" href="#Library-Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter" href="#Library-Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
</td></tr></table>
<table class="index-cp" border="0">
<tr><td></td><th align="left">Index Entry</th><td>&nbsp;</td><th align="left"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Library-Index_cp_letter-E">E</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fCANCELLATION">OMP_CANCELLATION</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-1">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fDISPLAY_005fENV">OMP_DISPLAY_ENV</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-2">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fDEFAULT_005fDEVICE">OMP_DEFAULT_DEVICE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-3">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-4">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fMAX_005fACTIVE_005fLEVELS">OMP_MAX_ACTIVE_LEVELS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-5">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fMAX_005fTASK_005fPRIORITY">OMP_MAX_TASK_PRIORITY</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-6">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNESTED">OMP_NESTED</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-7">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-8">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-9">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fPLACES">OMP_PLACES</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-10">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSTACKSIZE">OMP_STACKSIZE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-11">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-12">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fTHREAD_005fLIMIT">OMP_THREAD_LIMIT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-13">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fWAIT_005fPOLICY">OMP_WAIT_POLICY</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-14">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-15">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fDEBUG">GOMP_DEBUG</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-16">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-17">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSPINCOUNT">GOMP_SPINCOUNT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-18">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fRTEMS_005fTHREAD_005fPOOLS">GOMP_RTEMS_THREAD_POOLS</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Library-Index_cp_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-FDL_002c-GNU-Free-Documentation-License">FDL, GNU Free Documentation License</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Library-Index_cp_letter-I">I</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNESTED">OMP_NESTED</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-1">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-2">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-3">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-4">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSPINCOUNT">GOMP_SPINCOUNT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-5">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fRTEMS_005fTHREAD_005fPOOLS">GOMP_RTEMS_THREAD_POOLS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Introduction">Introduction</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Top">Top</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Library-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter" href="#Library-Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter" href="#Library-Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
</td></tr></table>

<div class="footnote">
<hr>
<h4 class="footnotes-heading">Footnotes</h4>

<h3><a name="FOOT1" href="#DOCF1">(1)</a></h3>
<p>See &quot;Stream Management&quot; in &quot;CUDA Driver API&quot;,
TRM-06703-001, Version 5.5, for additional information</p>
<h3><a name="FOOT2" href="#DOCF2">(2)</a></h3>
<p>See section 2.26,
&quot;Interactions with the CUDA Driver API&quot; in
&quot;CUDA Runtime API&quot;, Version 5.5, and section 2.27, &quot;VDPAU
Interoperability&quot;, in &quot;CUDA Driver API&quot;, TRM-06703-001, Version 5.5,
for additional information on library interoperability.</p>
<h3><a name="FOOT3" href="#DOCF3">(3)</a></h3>
<p>More complete information
about <code>ACC_DEVICE_TYPE</code> and <code>ACC_DEVICE_NUM</code> can be found in
sections 4.1 and 4.2 of the <a href="https://www.openacc.org">OpenACC</a>
Application Programming Interface”, Version 2.0.</p>
</div>
<hr>



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