cuda.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <mpi.h>
#include <cuda_runtime.h>

int main(int argc, char **argv)
{
  int i;
  int myid, nprocs, ierr, provided;
  MPI_Status status;
  int N = 1000, loops;
  double time, t_min=999999.99, t_max=0.0, t_sum=0.0;
  double *data, *d_data;
  int gpu=-1;

  if(argc!=4){
    printf("usage: %s length loops gpuid\n", argv[0]);
    return -1;
  }

  N = atoi(argv[1]);
  loops = atoi(argv[2]);

  //ierr = MPI_Init_thread(&argc,&argv,MPI_THREAD_FUNNELED,&provided);
  //if(provided!=MPI_THREAD_FUNNELED)printf("MPI_THREAD_FUNNELED is not provided.\n");
  ierr = MPI_Init(&argc,&argv);
  ierr = MPI_Comm_rank(MPI_COMM_WORLD, &myid);
  ierr = MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
  if(nprocs!=1){
    printf("1 process is required.\n");
    return -1;
  }

  data = (double*)malloc(sizeof(double)*N);

  gpu = atoi(argv[3]);
  printf("cudaSetDevice(%d)\n", gpu);
  cudaSetDevice(gpu);
  cudaMalloc((void*)&d_data, sizeof(double)*N);

  for(i=0; i<10; i++){
    cudaMemcpy(d_data, data, sizeof(double)*N, cudaMemcpyHostToDevice);
    cudaMemcpy(data, d_data, sizeof(double)*N, cudaMemcpyDeviceToHost);
  }
  for(i=0; i<loops; i++){
    time = MPI_Wtime();
    cudaMemcpy(d_data, data, sizeof(double)*N, cudaMemcpyHostToDevice);
    cudaMemcpy(data, d_data, sizeof(double)*N, cudaMemcpyDeviceToHost);
    time = MPI_Wtime() - time;
    if(time>t_max)t_max=time;
    if(time<t_min)t_min=time;
    t_sum += time;
  }
  printf("TIME %d : %e (average %e msec, min %e msec, max %e msec)\n", myid, t_sum,
	 t_sum/(double)loops*1000.0,
	 t_min*1000.0,
	 t_max*1000.0
	 );

  cudaFree(d_data);
  free(data);

  ierr = MPI_Finalize();

  return 0;
}