Better when you're using OpenMP offloading

cuda_fft.cpp

+#include <stdlib.h>
+#include <stdio.h>
+#include <cufftMp.h>
+#include <mpi.h>
+#include <cuda_runtime.h>
+#include <complex.h>
+#include "cuComplex.h"
+#include "w-stacking_omp.h"
+#include <time.h>
+
+#if defined(CUFFTMP) && !defined(USE_FFTW)
+
+void cuda_fft(
+	      int num_w_planes,
+	      int grid_size_x,
+	      int grid_size_y,
+	      int xaxis,
+	      int yaxis,
+	      double * grid,
+	      double * gridss,
+	      int rank,
+	      MPI_Comm comm)
+{
+
+ #if !defined __CUDACC__
+  int ndevices;
+  cudaGetDeviceCount(&ndevices);
+  cudaSetDevice(rank % ndevices);
+
+  if ( rank == 0 ) {
+    if (0 == ndevices) {
+      
+      shutdown_wstacking(NO_ACCELERATORS_FOUND, "No accelerators found", __FILE__, __LINE__ );
+    }
+  }
+ #endif
+  
+  cudaError_t mmm;
+  cufftResult_t status;
+
+  cufftDoubleComplex *fftwgrid;
+  fftwgrid = (cufftDoubleComplex*) malloc(sizeof(cufftDoubleComplex)*2*num_w_planes*yaxis*grid_size_x);
+
+
+
+  // Plan creation
+
+  cufftHandle plan;
+  status = cufftCreate(&plan);
+  if (status != CUFFT_SUCCESS) {printf("!!! cufftCreate ERROR %d !!!\n", status);}
+
+  cudaStream_t stream{};
+  cudaStreamCreate(&stream);
+
+
+  status = cufftMpAttachComm(plan, CUFFT_COMM_MPI, &comm);
+  if (status != CUFFT_SUCCESS) {printf("!!! cufftMpAttachComm ERROR %d !!!\n", status);}
+
+  status = cufftSetStream(plan, stream);
+  if (status != CUFFT_SUCCESS) {printf("!!! cufftSetStream ERROR %d !!!\n", status);}
+
+  size_t workspace;
+  status = cufftMakePlan2d(plan, grid_size_x, grid_size_y, CUFFT_Z2Z, &workspace);
+  if (status != CUFFT_SUCCESS) {printf("!!! cufftMakePlan2d ERROR %d !!!\n", status);}
+  cudaDeviceSynchronize();
+
+
+
+  uint fftwindex = 0;
+  uint fftwindex2D = 0;
+  double norm = 1.0/(double)(grid_size_x*grid_size_y);
+
+
+
+
+  // Grid composition
+
+  for (int iw=0; iw<num_w_planes; iw++)
+    {
+      printf("select the %d w-plane to transform\n", iw);
+      for (int iv=0; iv<yaxis; iv++)
+	{
+	  for (int iu=0; iu<xaxis; iu++)
+	    {
+	      fftwindex2D = iu + iv*xaxis;
+	      fftwindex = 2*(fftwindex2D + iw*xaxis*yaxis);
+	      fftwgrid[fftwindex2D].x = grid[fftwindex];
+	      fftwgrid[fftwindex2D].y = grid[fftwindex+1];
+	    }
+	}
+
+
+      cudaLibXtDesc *fftwgrid_g;
+      cudaLibXtDesc *fftwgrid_g2;
+
+
+      status = cufftXtMalloc(plan, &fftwgrid_g, CUFFT_XT_FORMAT_INPLACE);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtMalloc ERROR %d !!!\n", status);}
+
+      status = cufftXtMalloc(plan, &fftwgrid_g2, CUFFT_XT_FORMAT_INPLACE);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtMalloc 2 ERROR %d !!!\n", status);}
+      cudaDeviceSynchronize();
+
+      mmm = cudaStreamSynchronize(stream);
+      if (mmm != cudaSuccess) {printf("!!! cudaStreamSynchronize ERROR %d !!!\n", mmm);}
+
+      status = cufftXtMemcpy(plan, fftwgrid_g, fftwgrid, CUFFT_COPY_HOST_TO_DEVICE);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtMemcpy htd fftwgrid_g ERROR %d !!!\n", status);}
+
+      cudaDeviceSynchronize();
+
+      status = cufftXtExecDescriptor(plan, fftwgrid_g, fftwgrid_g, CUFFT_INVERSE);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtExecDescriptor ERROR %d !!!\n", status);}
+
+
+      mmm = cudaStreamSynchronize(stream);
+      if (mmm != cudaSuccess) {printf("!!! cudaStreamSynchronize 2 ERROR %d !!!\n", mmm);}
+
+      cudaDeviceSynchronize();
+
+
+      status = cufftXtMemcpy(plan, fftwgrid_g2, fftwgrid_g, CUFFT_COPY_DEVICE_TO_DEVICE);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtMemcpy dtd fftwgrid ERROR %d !!!\n", status);}
+
+
+      mmm = cudaStreamSynchronize(stream);
+      if (mmm != cudaSuccess) {printf("!!! cudaStreamSynchronize 2 ERROR %d !!!\n", mmm);}
+
+      cudaDeviceSynchronize();
+
+      status = cufftXtMemcpy(plan, fftwgrid, fftwgrid_g2, CUFFT_COPY_DEVICE_TO_HOST);
+      if (status != CUFFT_SUCCESS) {printf("!!! cufftXtMemcpy dth fftwgrid ERROR %d !!!\n", status);}
+
+
+      cufftXtFree(fftwgrid_g);
+      cufftXtFree(fftwgrid_g2);
+
+      for (int iv=0; iv<yaxis; iv++)
+	{
+	  for (int iu=0; iu<xaxis; iu++)
+	    {
+	      fftwindex2D = iu + iv*xaxis;
+	      fftwindex = 2*(fftwindex2D + iw*xaxis*yaxis);
+	      gridss[fftwindex] = norm*fftwgrid[fftwindex2D].x;
+	      gridss[fftwindex+1] = norm*fftwgrid[fftwindex2D].y;
+	    }
+	}
+    }
+
+
+
+  status = cufftDestroy(plan);
+  if (status != CUFFT_SUCCESS) {printf("!!! cufftDestroy fftwgrid ERROR %d !!!\n", status);}
+
+
+  cudaStreamDestroy(stream);
+  cudaDeviceSynchronize();
+
+}
+#endif 
+