src/gromacs/fft/gpu_3dfft_ocl.cpp

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  35
  36 /*! \internal \file
  37  *  \brief Implements GPU 3D FFT routines for OpenCL.
  38  *
  39  *  \author Aleksei Iupinov <a.yupinov@gmail.com>
  40  *  \author Mark Abraham <mark.j.abraham@gmail.com>
  41  *  \ingroup module_fft
  42  */
  43
  44 #include "gmxpre.h"
  45
  46 #include "gpu_3dfft.h"
  47
  48 #include <array>
  49 #include <vector>
  50
  51 #include <clFFT.h>
  52
  53 #include "gromacs/gpu_utils/device_context.h"
  54 #include "gromacs/gpu_utils/device_stream.h"
  55 #include "gromacs/gpu_utils/gmxopencl.h"
  56 #include "gromacs/utility/exceptions.h"
  57 #include "gromacs/utility/gmxassert.h"
  58 #include "gromacs/utility/stringutil.h"
  59
  60 namespace gmx
  61 {
  62
  63 class Gpu3dFft::Impl
  64 {
  65 public:
  66     Impl(ivec                 realGridSize,
  67          ivec                 realGridSizePadded,
  68          ivec                 complexGridSizePadded,
  69          bool                 useDecomposition,
  70          bool                 performOutOfPlaceFFT,
  71          const DeviceContext& context,
  72          const DeviceStream&  pmeStream,
  73          DeviceBuffer<float>  realGrid,
  74          DeviceBuffer<float>  complexGrid);
  75     ~Impl();
  76
  77     clfftPlanHandle               planR2C_;
  78     clfftPlanHandle               planC2R_;
  79     std::vector<cl_command_queue> commandStreams_;
  80     cl_mem                        realGrid_;
  81     cl_mem                        complexGrid_;
  82 };
  83
  84 //! Throws the exception on clFFT error
  85 static void handleClfftError(clfftStatus status, const char* msg)
  86 {
  87     // Supposedly it's just a superset of standard OpenCL errors
  88     if (status != CLFFT_SUCCESS)
  89     {
  90         GMX_THROW(InternalError(formatString("%s: %d", msg, status)));
  91     }
  92 }
  93
  94 Gpu3dFft::Impl::Impl(ivec                 realGridSize,
  95                      ivec                 realGridSizePadded,
  96                      ivec                 complexGridSizePadded,
  97                      const bool           useDecomposition,
  98                      const bool           performOutOfPlaceFFT,
  99                      const DeviceContext& context,
 100                      const DeviceStream&  pmeStream,
 101                      DeviceBuffer<float>  realGrid,
 102                      DeviceBuffer<float>  complexGrid) :
 103     realGrid_(realGrid), complexGrid_(complexGrid)
 104 {
 105     GMX_RELEASE_ASSERT(!useDecomposition, "FFT decomposition not implemented");
 106
 107     cl_context clContext = context.context();
 108     commandStreams_.push_back(pmeStream.stream());
 109
 110     // clFFT expects row-major, so dimensions/strides are reversed (ZYX instead of XYZ)
 111     std::array<size_t, DIM> realGridDimensions = { size_t(realGridSize[ZZ]),
 112                                                    size_t(realGridSize[YY]),
 113                                                    size_t(realGridSize[XX]) };
 114     std::array<size_t, DIM> realGridStrides    = {
 115         1, size_t(realGridSizePadded[ZZ]), size_t(realGridSizePadded[YY] * realGridSizePadded[ZZ])
 116     };
 117     std::array<size_t, DIM> complexGridStrides = {
 118         1, size_t(complexGridSizePadded[ZZ]), size_t(complexGridSizePadded[YY] * complexGridSizePadded[ZZ])
 119     };
 120
 121     constexpr clfftDim dims = CLFFT_3D;
 122     handleClfftError(clfftCreateDefaultPlan(&planR2C_, clContext, dims, realGridDimensions.data()),
 123                      "clFFT planning failure");
 124     handleClfftError(clfftSetResultLocation(planR2C_, performOutOfPlaceFFT ? CLFFT_OUTOFPLACE : CLFFT_INPLACE),
 125                      "clFFT planning failure");
 126     handleClfftError(clfftSetPlanPrecision(planR2C_, CLFFT_SINGLE), "clFFT planning failure");
 127     constexpr cl_float scale = 1.0;
 128     handleClfftError(clfftSetPlanScale(planR2C_, CLFFT_FORWARD, scale),
 129                      "clFFT coefficient setup failure");
 130     handleClfftError(clfftSetPlanScale(planR2C_, CLFFT_BACKWARD, scale),
 131                      "clFFT coefficient setup failure");
 132
 133     // The only difference between 2 plans is direction
 134     handleClfftError(clfftCopyPlan(&planC2R_, clContext, planR2C_), "clFFT plan copying failure");
 135
 136     handleClfftError(clfftSetLayout(planR2C_, CLFFT_REAL, CLFFT_HERMITIAN_INTERLEAVED),
 137                      "clFFT R2C layout failure");
 138     handleClfftError(clfftSetLayout(planC2R_, CLFFT_HERMITIAN_INTERLEAVED, CLFFT_REAL),
 139                      "clFFT C2R layout failure");
 140
 141     handleClfftError(clfftSetPlanInStride(planR2C_, dims, realGridStrides.data()),
 142                      "clFFT stride setting failure");
 143     handleClfftError(clfftSetPlanOutStride(planR2C_, dims, complexGridStrides.data()),
 144                      "clFFT stride setting failure");
 145
 146     handleClfftError(clfftSetPlanInStride(planC2R_, dims, complexGridStrides.data()),
 147                      "clFFT stride setting failure");
 148     handleClfftError(clfftSetPlanOutStride(planC2R_, dims, realGridStrides.data()),
 149                      "clFFT stride setting failure");
 150
 151     handleClfftError(clfftBakePlan(planR2C_, commandStreams_.size(), commandStreams_.data(), nullptr, nullptr),
 152                      "clFFT precompiling failure");
 153     handleClfftError(clfftBakePlan(planC2R_, commandStreams_.size(), commandStreams_.data(), nullptr, nullptr),
 154                      "clFFT precompiling failure");
 155
 156     // TODO: implement solve kernel as R2C FFT callback
 157     // TODO: disable last transpose (clfftSetPlanTransposeResult)
 158 }
 159
 160 Gpu3dFft::Impl::~Impl()
 161 {
 162     clfftDestroyPlan(&planR2C_);
 163     clfftDestroyPlan(&planC2R_);
 164 }
 165
 166 void Gpu3dFft::perform3dFft(gmx_fft_direction dir, CommandEvent* timingEvent)
 167 {
 168     cl_mem                            tempBuffer = nullptr;
 169     constexpr std::array<cl_event, 0> waitEvents{ {} };
 170
 171     clfftPlanHandle plan;
 172     clfftDirection  direction;
 173     cl_mem *        inputGrids, *outputGrids;
 174
 175     switch (dir)
 176     {
 177         case GMX_FFT_REAL_TO_COMPLEX:
 178             plan        = impl_->planR2C_;
 179             direction   = CLFFT_FORWARD;
 180             inputGrids  = &impl_->realGrid_;
 181             outputGrids = &impl_->complexGrid_;
 182             break;
 183         case GMX_FFT_COMPLEX_TO_REAL:
 184             plan        = impl_->planC2R_;
 185             direction   = CLFFT_BACKWARD;
 186             inputGrids  = &impl_->complexGrid_;
 187             outputGrids = &impl_->realGrid_;
 188             break;
 189         default:
 190             GMX_THROW(NotImplementedError("The chosen 3D-FFT case is not implemented on GPUs"));
 191     }
 192     handleClfftError(clfftEnqueueTransform(plan,
 193                                            direction,
 194                                            impl_->commandStreams_.size(),
 195                                            impl_->commandStreams_.data(),
 196                                            waitEvents.size(),
 197                                            waitEvents.data(),
 198                                            timingEvent,
 199                                            inputGrids,
 200                                            outputGrids,
 201                                            tempBuffer),
 202                      "clFFT execution failure");
 203 }
 204
 205 Gpu3dFft::Gpu3dFft(ivec                 realGridSize,
 206                    ivec                 realGridSizePadded,
 207                    ivec                 complexGridSizePadded,
 208                    const bool           useDecomposition,
 209                    const bool           performOutOfPlaceFFT,
 210                    const DeviceContext& context,
 211                    const DeviceStream&  pmeStream,
 212                    DeviceBuffer<float>  realGrid,
 213                    DeviceBuffer<float>  complexGrid) :
 214     impl_(std::make_unique<Impl>(realGridSize,
 215                                  realGridSizePadded,
 216                                  complexGridSizePadded,
 217                                  useDecomposition,
 218                                  performOutOfPlaceFFT,
 219                                  context,
 220                                  pmeStream,
 221                                  realGrid,
 222                                  complexGrid))
 223 {
 224 }
 225
 226 Gpu3dFft::~Gpu3dFft() = default;
 227
 228 } // namespace gmx