Timing MPI routines

time_mpi.c

#include <mpi.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
    int num = 7;
    int i;
    int rank;
    double begin, end;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Barrier(MPI_COMM_WORLD);
    begin = MPI_Wtime();
    for (i = 0; i != 1000000; ++i) {
        MPI_Bcast(&num, 1, MPI_INT, 0, MPI_COMM_WORLD);
    }
    MPI_Barrier(MPI_COMM_WORLD);
    end = MPI_Wtime();
    MPI_Finalize();

    if (rank == 0) {
        printf("Run time: %f\n", end-begin);
    }
}