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37 * \brief Implements PME-PP communication using CUDA
40 * \author Alan Gray <alang@nvidia.com>
42 * \ingroup module_ewald
46 #include "gromacs/ewald/pme_pp_communication.h"
47 #include "pme_pp_comm_gpu_impl.h"
51 #include "gromacs/gpu_utils/cudautils.cuh"
52 #include "gromacs/gpu_utils/device_context.h"
53 #include "gromacs/gpu_utils/device_stream.h"
54 #include "gromacs/gpu_utils/devicebuffer.h"
55 #include "gromacs/gpu_utils/gpueventsynchronizer.h"
56 #include "gromacs/gpu_utils/typecasts.cuh"
57 #include "gromacs/utility/gmxmpi.h"
62 PmePpCommGpu::Impl::Impl(MPI_Comm comm,
64 std::vector<gmx::RVec>* pmeCpuForceBuffer,
65 const DeviceContext& deviceContext,
66 const DeviceStream& deviceStream) :
67 deviceContext_(deviceContext),
68 pmePpCommStream_(deviceStream),
71 pmeCpuForceBuffer_(pmeCpuForceBuffer),
76 PmePpCommGpu::Impl::~Impl() = default;
78 void PmePpCommGpu::Impl::reinit(int size)
80 // Reallocate device buffer used for staging PME force
81 reallocateDeviceBuffer(&d_pmeForces_, size, &d_pmeForcesSize_, &d_pmeForcesSizeAlloc_, deviceContext_);
83 // This rank will access PME rank memory directly, so needs to receive the remote PME buffer addresses.
88 // receive device coordinate buffer address from PME rank
89 MPI_Recv(&remotePmeXBuffer_, sizeof(float3*), MPI_BYTE, pmeRank_, 0, comm_, MPI_STATUS_IGNORE);
90 // send host and device force buffer addresses to PME rank
91 MPI_Send(&d_pmeForces_, sizeof(float3*), MPI_BYTE, pmeRank_, 0, comm_);
92 RVec* pmeCpuForceBufferData = pmeCpuForceBuffer_->data();
93 MPI_Send(&pmeCpuForceBufferData, sizeof(RVec*), MPI_BYTE, pmeRank_, 0, comm_);
94 // Receive address of event and associated flag from PME rank, to allow sync to local stream after force transfer
95 // NOLINTNEXTLINE(bugprone-sizeof-expression)
96 MPI_Recv(&remotePmeForceSendEvent_, sizeof(GpuEventSynchronizer*), MPI_BYTE, pmeRank_, 0, comm_, MPI_STATUS_IGNORE);
97 MPI_Recv(&remotePmeForceSendEventRecorded_, sizeof(std::atomic<bool>*), MPI_BYTE, pmeRank_, 0, comm_, MPI_STATUS_IGNORE);
103 void PmePpCommGpu::Impl::receiveForceFromPmeCudaDirect(bool receivePmeForceToGpu)
106 // Wait until remote PME task has pushed data, and then enqueue remote event to local stream.
108 // Spin until PME rank sets flag
109 while (!(remotePmeForceSendEventRecorded_->load(std::memory_order_acquire))) {};
111 // Enqueue remote event
112 remotePmeForceSendEvent_->enqueueWaitEvent(pmePpCommStream_);
115 remotePmeForceSendEventRecorded_->store(false, std::memory_order_release);
117 if (receivePmeForceToGpu)
119 // Record event to be enqueued in the GPU local buffer operations, to
120 // satisfy dependency on receiving the PME force data before
121 // reducing it with the other force contributions.
122 forcesReadySynchronizer_.markEvent(pmePpCommStream_);
126 // Ensure CPU waits for PME forces to be copied before reducing
127 // them with other forces on the CPU
128 pmePpCommStream_.synchronize();
133 void PmePpCommGpu::Impl::receiveForceFromPmeCudaMpi(float3* pmeForcePtr, int recvSize)
136 MPI_Recv(pmeForcePtr, recvSize * DIM, MPI_FLOAT, pmeRank_, 0, comm_, MPI_STATUS_IGNORE);
138 GMX_UNUSED_VALUE(pmeForcePtr);
139 GMX_UNUSED_VALUE(recvSize);
143 void PmePpCommGpu::Impl::receiveForceFromPme(float3* recvPtr, int recvSize, bool receivePmeForceToGpu)
145 float3* pmeForcePtr = receivePmeForceToGpu ? asFloat3(d_pmeForces_) : recvPtr;
148 receiveForceFromPmeCudaDirect(receivePmeForceToGpu);
152 receiveForceFromPmeCudaMpi(pmeForcePtr, recvSize);
156 void PmePpCommGpu::Impl::sendCoordinatesToPmeCudaDirect(float3* sendPtr,
158 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent)
160 // ensure stream waits until coordinate data is available on device
161 coordinatesReadyOnDeviceEvent->enqueueWaitEvent(pmePpCommStream_);
163 cudaError_t stat = cudaMemcpyAsync(remotePmeXBuffer_,
165 sendSize * DIM * sizeof(float),
167 pmePpCommStream_.stream());
168 CU_RET_ERR(stat, "cudaMemcpyAsync on Send to PME CUDA direct data transfer failed");
171 // Record and send event to allow PME task to sync to above transfer before commencing force calculations
172 pmeCoordinatesSynchronizer_.markEvent(pmePpCommStream_);
173 GpuEventSynchronizer* pmeSync = &pmeCoordinatesSynchronizer_;
174 // NOLINTNEXTLINE(bugprone-sizeof-expression)
175 MPI_Send(&pmeSync, sizeof(GpuEventSynchronizer*), MPI_BYTE, pmeRank_, 0, comm_);
179 void PmePpCommGpu::Impl::sendCoordinatesToPmeCudaMpi(float3* sendPtr,
181 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent)
183 // ensure coordinate data is available on device before we start transfer
184 coordinatesReadyOnDeviceEvent->waitForEvent();
187 float3* sendptr_x = sendPtr;
189 MPI_Send(sendptr_x, sendSize * DIM, MPI_FLOAT, pmeRank_, eCommType_COORD_GPU, comm_);
191 GMX_UNUSED_VALUE(sendPtr);
192 GMX_UNUSED_VALUE(sendSize);
196 void PmePpCommGpu::Impl::sendCoordinatesToPme(float3* sendPtr,
198 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent)
202 sendCoordinatesToPmeCudaDirect(sendPtr, sendSize, coordinatesReadyOnDeviceEvent);
206 sendCoordinatesToPmeCudaMpi(sendPtr, sendSize, coordinatesReadyOnDeviceEvent);
209 DeviceBuffer<Float3> PmePpCommGpu::Impl::getGpuForceStagingPtr()
214 GpuEventSynchronizer* PmePpCommGpu::Impl::getForcesReadySynchronizer()
218 return &forcesReadySynchronizer_;
226 PmePpCommGpu::PmePpCommGpu(MPI_Comm comm,
228 std::vector<gmx::RVec>* pmeCpuForceBuffer,
229 const DeviceContext& deviceContext,
230 const DeviceStream& deviceStream) :
231 impl_(new Impl(comm, pmeRank, pmeCpuForceBuffer, deviceContext, deviceStream))
235 PmePpCommGpu::~PmePpCommGpu() = default;
237 void PmePpCommGpu::reinit(int size)
242 void PmePpCommGpu::receiveForceFromPme(RVec* recvPtr, int recvSize, bool receivePmeForceToGpu)
244 impl_->receiveForceFromPme(asFloat3(recvPtr), recvSize, receivePmeForceToGpu);
247 void PmePpCommGpu::sendCoordinatesToPmeFromGpu(DeviceBuffer<RVec> sendPtr,
249 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent)
251 impl_->sendCoordinatesToPme(asFloat3(sendPtr), sendSize, coordinatesReadyOnDeviceEvent);
254 void PmePpCommGpu::sendCoordinatesToPmeFromCpu(RVec* sendPtr,
256 GpuEventSynchronizer* coordinatesReadyOnDeviceEvent)
258 impl_->sendCoordinatesToPme(asFloat3(sendPtr), sendSize, coordinatesReadyOnDeviceEvent);
261 DeviceBuffer<Float3> PmePpCommGpu::getGpuForceStagingPtr()
263 return impl_->getGpuForceStagingPtr();
266 GpuEventSynchronizer* PmePpCommGpu::getForcesReadySynchronizer()
268 return impl_->getForcesReadySynchronizer();