/usr/include/gromacs/utility/alignedallocator.h is in libgromacs-dev 2018.1-1.
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* This file is part of the GROMACS molecular simulation package.
*
* Copyright (c) 2017, by the GROMACS development team, led by
* Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
* and including many others, as listed in the AUTHORS file in the
* top-level source directory and at http://www.gromacs.org.
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/*! \file
* \brief Declares allocation policy classes and allocators that are
* used to make library containers compatible with alignment
* requirements of particular hardware, e.g. memory operations for
* SIMD or accelerators.
*
* \author Erik Lindahl <erik.lindahl@gmail.com>
* \author Mark Abraham <mark.j.abraham@gmail.com>
* \inpublicapi
* \ingroup module_utility
*/
#ifndef GMX_UTILITY_ALIGNEDALLOCATOR_H
#define GMX_UTILITY_ALIGNEDALLOCATOR_H
#include <cstddef>
#include "gromacs/utility/allocator.h"
namespace gmx
{
/*! \libinternal \brief Policy class for configuring gmx::Allocator, to manage
* allocations of aligned memory for SIMD code.
*/
class AlignedAllocationPolicy
{
public:
/*! \brief Return the alignment size. */
static std::size_t
alignment();
/*! \brief Allocate memory aligned to alignment() bytes.
*
* \param bytes Amount of memory (bytes) to allocate. It is valid to ask for
* 0 bytes, which will return a non-null pointer that is properly
* aligned and padded (but that you should not use).
*
* \return Valid pointer if the allocation worked, otherwise nullptr.
*
* The memory will always be aligned to 128 bytes, which is our
* estimate of the longest cache lines on architectures currently in use.
* It will also be padded by the same amount at the end of the
* area, to help avoid false cache sharing.
*
* \note Memory allocated with this routine must be released with
* gmx::AlignedAllocationPolicy::free(), and absolutely not the system free().
*/
static void *
malloc(std::size_t bytes);
/*! \brief Free aligned memory
*
* \param p Memory pointer previously returned from malloc()
*
* \note This routine should only be called with pointers obtained from
* gmx::AlignedAllocationPolicy::malloc(), and absolutely not any
* pointers obtained the system malloc().
*/
static void
free(void *p);
};
/*! \brief Aligned memory allocator.
*
* \tparam T Type of objects to allocate
*
* This convenience partial specialization can be used for the
* optional allocator template parameter in standard library
* containers, which is necessary e.g. to use SIMD aligned load and
* store operations on data in those containers. The memory will
* always be aligned according to the behavior of
* AlignedAllocationPolicy.
*/
template <class T>
using AlignedAllocator = Allocator<T, AlignedAllocationPolicy>;
/*! \brief Return the memory page size on this system
*
* Implements the "construct on first use" idiom to avoid the static
* initialization order fiasco where a possible static page-aligned
* container would be initialized before the alignment variable was.
*
* Note that thread-safety is guaranteed by the C++11 language
* standard. */
std::size_t pageSize();
/*! \libinternal \brief Policy class for configuring gmx::Allocator,
* to manage allocations of page-aligned memory that can be locked for
* asynchronous transfer to GPU devices.
*/
class PageAlignedAllocationPolicy
{
public:
/*! \brief Return the alignment size of memory pages on this system.
*
* Queries sysconf/WinAPI, otherwise guesses 4096. */
static std::size_t
alignment();
/*! \brief Allocate memory aligned to alignment() bytes.
*
* \param bytes Amount of memory (bytes) to allocate. It is valid to ask for
* 0 bytes, which will return a non-null pointer that is properly
* aligned and padded (but that you should not use).
*
* \return Valid pointer if the allocation worked, otherwise nullptr.
*
* \note Memory allocated with this routine must be released with
* gmx::PageAlignedAllocationPolicy::free(), and absolutely not the system free().
*/
static void *
malloc(std::size_t bytes);
/*! \brief Free aligned memory
*
* \param p Memory pointer previously returned from malloc()
*
* \note This routine should only be called with pointers obtained from
* gmx::PageAlignedAllocationPolicy::malloc(), and absolutely not any
* pointers obtained the system malloc().
*/
static void
free(void *p);
};
/*! \brief PageAligned memory allocator.
*
* \tparam T Type of objects to allocate
*
* This convenience partial specialization can be used for the
* optional allocator template parameter in standard library
* containers, which is necessary for locking memory pages for
* asynchronous transfer between a GPU device and the host. The
* memory will always be aligned according to the behavior of
* PageAlignedAllocationPolicy.
*/
template <class T>
using PageAlignedAllocator = Allocator<T, PageAlignedAllocationPolicy>;
} // namespace gmx
#endif // GMX_UTILITY_ALIGNEDALLOCATOR_H
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