MPI+OpenMP混合编程

experiment

MPI+OpenMP混合编程

demo

下面给出demo程序

#include "mpi.h"
#include "omp.h"
#include <math.h>
#define N 1000000000
int main( int  argc, char* argv[] ){
    int rank, nproc;
    int  i,low,up;
    double local = 0.0, pi, w, temp;
    MPI_Status  status;
    MPI_Init( &argc, &argv );
    MPI_Comm_size( MPI_COMM_WORLD, &nproc );
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );
    w = 1.0/N; low = rank*(N / nproc); up = low + N/nproc - 1;
#pragma omp parallel for reduction(+:local) private(temp,i)
     for (i=low;i<up; i++){
          temp = (i+0.5)*w;
          local = local + 4.0/(1.0+temp*temp);
     }
    MPI_Reduce(&local, &pi, 1, MPI_DOUBLE, MPI_SUM, 0,MPI_COMM_WORLD);
    if(rank==0) printf("pi = %.20f\n",pi*w);
    MPI_Finalize();
}

编译

mpicc -o pi -fopenmp test.c

设置环境变量

export OMP_NUM_THREADS=8

运行

mpirun -np 4 -hostfile ./mynodes ./pi