src/gromacs/gpu_utils/hostallocator.cpp

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  35 /*! \internal \file
  36  * \brief Implements gmx::HostAllocationPolicy for allocating memory
  37  * suitable for e.g. GPU transfers on CUDA.
  38  *
  39  * \author Mark Abraham <mark.j.abraham@gmail.com>
  40  */
  41 #include "gmxpre.h"
  42
  43 #include "hostallocator.h"
  44
  45 #include "config.h"
  46
  47 #include <cstddef>
  48
  49 #include <memory>
  50
  51 #include "gromacs/utility/alignedallocator.h"
  52 #include "gromacs/utility/gmxassert.h"
  53 #include "gromacs/utility/stringutil.h"
  54
  55 #include "pinning.h"
  56
  57 namespace gmx
  58 {
  59
  60 //! Private implementation class.
  61 class HostAllocationPolicy::Impl
  62 {
  63     public:
  64         /*! \brief Pointer to the last unfreed allocation, or nullptr
  65          * if no allocation exists.
  66          *
  67          * Note that during e.g. std::vector.resize() a call to its
  68          * allocator's allocate() function precedes the call to its
  69          * allocator's deallocate() function for freeing the old
  70          * buffer after the data has been copied from it. So in
  71          * general, pointer_ will not match the argument received by
  72          * free(). */
  73         void         *pointer_ = nullptr;
  74         //! Number of bytes in the last unfreed allocation.
  75         std::size_t   numBytes_ = 0;
  76         //! The pointer to any storage that has been pinned, or nullptr if none has been pinned.
  77         void         *pinnedPointer_ = nullptr;
  78         //! Whether this object is in mode where new allocations will be pinned by default.
  79         PinningPolicy pinningPolicy_ = PinningPolicy::CannotBePinned;
  80 };
  81
  82 HostAllocationPolicy::HostAllocationPolicy() : impl_(std::make_shared<Impl>())
  83 {
  84 }
  85
  86 std::size_t HostAllocationPolicy::alignment()
  87 {
  88     return (impl_->pinningPolicy_ == PinningPolicy::CanBePinned ?
  89             PageAlignedAllocationPolicy::alignment() :
  90             AlignedAllocationPolicy::alignment());
  91 }
  92 void *HostAllocationPolicy::malloc(std::size_t bytes) const noexcept
  93 {
  94     // A container could have a pinned allocation that is being
  95     // extended, in which case we must un-pin while we still know the
  96     // old pinned vector, and which also ensures we don't pin two
  97     // buffers at the same time. If there's no allocation, or it isn't
  98     // pinned, then attempting to unpin it is OK, too.
  99     unpin();
 100     impl_->pointer_ = (impl_->pinningPolicy_ == PinningPolicy::CanBePinned ?
 101                        PageAlignedAllocationPolicy::malloc(bytes) :
 102                        AlignedAllocationPolicy::malloc(bytes));
 103
 104     if (impl_->pointer_ != nullptr)
 105     {
 106         impl_->numBytes_ = bytes;
 107     }
 108     pin();
 109     return impl_->pointer_;
 110 }
 111
 112 void HostAllocationPolicy::free(void *buffer) const noexcept
 113 {
 114     unpin();
 115     if (buffer == nullptr)
 116     {
 117         // Nothing to do
 118         return;
 119     }
 120     if (impl_->pinningPolicy_ == PinningPolicy::CanBePinned)
 121     {
 122         PageAlignedAllocationPolicy::free(buffer);
 123     }
 124     else
 125     {
 126         AlignedAllocationPolicy::free(buffer);
 127     }
 128     impl_->pointer_  = nullptr;
 129     impl_->numBytes_ = 0;
 130 }
 131
 132 PinningPolicy HostAllocationPolicy::pinningPolicy() const
 133 {
 134     return impl_->pinningPolicy_;
 135 }
 136
 137 void HostAllocationPolicy::setPinningPolicy(PinningPolicy pinningPolicy)
 138 {
 139     if (GMX_GPU != GMX_GPU_CUDA)
 140     {
 141         GMX_RELEASE_ASSERT(pinningPolicy == PinningPolicy::CannotBePinned,
 142                            "A suitable build of GROMACS (e.g. with CUDA) is required for a "
 143                            "HostAllocationPolicy to be set to a mode that produces pinning.");
 144     }
 145     impl_->pinningPolicy_ = pinningPolicy;
 146 }
 147
 148 void HostAllocationPolicy::pin() const noexcept
 149 {
 150     if (impl_->pinningPolicy_ == PinningPolicy::CannotBePinned ||
 151         impl_->pointer_ == nullptr ||
 152         impl_->pinnedPointer_ != nullptr)
 153     {
 154         // Do nothing if we're not in pinning mode, or the allocation
 155         // is empty, or it is already pinned.
 156         return;
 157     }
 158 #if GMX_GPU == GMX_GPU_CUDA
 159     pinBuffer(impl_->pointer_, impl_->numBytes_);
 160     impl_->pinnedPointer_ = impl_->pointer_;
 161 #else
 162     const char *errorMessage = "Could not register the host memory for pinning.";
 163
 164     GMX_RELEASE_ASSERT(impl_->pinningPolicy_ == PinningPolicy::CannotBePinned,
 165                        formatString("%s This build configuration must only have pinning policy "
 166                                     "that leads to no pinning.", errorMessage).c_str());
 167 #endif
 168 }
 169
 170 void HostAllocationPolicy::unpin() const noexcept
 171 {
 172     if (impl_->pinnedPointer_ == nullptr)
 173     {
 174         return;
 175     }
 176
 177 #if GMX_GPU == GMX_GPU_CUDA
 178     // Note that if the caller deactivated pinning mode, we still want
 179     // to be able to unpin if the allocation is still pinned.
 180
 181     unpinBuffer(impl_->pointer_);
 182     impl_->pinnedPointer_ = nullptr;
 183 #else
 184     GMX_RELEASE_ASSERT(impl_->pinnedPointer_ == nullptr,
 185                        "Since the build configuration does not support pinning, then "
 186                        "the pinned pointer must be nullptr.");
 187 #endif
 188 }
 189
 190 } // namespace gmx