gistfile1.c

#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
    int ierr;
    MPI_Datatype unit, mine[2], remote[2];
    int rcount[2];
    int roffset[2];
    int rmine[8];
    int rremote[8];
    int ranks[2];
    int size;
    int rank;
    int i;
    MPI_Aint bytes;
    MPI_Aint lb;
    int nroots = -1;
    int nleaves = 8;
    int bs = 2;
    int nranks = 2;
    MPI_Comm comm;
    MPI_Win win;

    double *rootdata;
    double *leafdata;
    ierr = MPI_Init(&argc, &argv);
    comm = MPI_COMM_WORLD;

    ierr = MPI_Comm_rank(comm, &rank);
    ierr = MPI_Comm_size(comm, &size);
    
    ierr = MPI_Type_contiguous(bs, MPI_DOUBLE, &unit);
    ierr = MPI_Type_commit(&unit);


    ranks[0] = 0;
    ranks[1] = 1;
    if ( rank == 0 ) {
        nroots = 3;
        roffset[0] = 0;
        roffset[1] = 3;
        rcount[0] = 3;
        rcount[1] = 5;
        rmine[0] = 0;
        rmine[1] = 1;
        rmine[2] = 2;
        rmine[3] = 3;
        rmine[4] = 7;
        rmine[5] = 5;
        rmine[6] = 4;
        rmine[7] = 6;
        rremote[0] = 0;
        rremote[1] = 1;
        rremote[2] = 2;
        rremote[3] = 1;
        rremote[4] = 5;
        rremote[5] = 3;
        rremote[6] = 2;
        rremote[7] = 4;
    } else if ( rank == 1 ) {
        nroots = 6;
        roffset[0] = 0;
        roffset[1] = 2;
        rcount[0] = 2;
        rcount[1] = 6;
        rmine[0] = 6;
        rmine[1] = 7;
        rmine[2] = 1;
        rmine[3] = 5;
        rmine[4] = 0;
        rmine[5] = 3;
        rmine[6] = 2;
        rmine[7] = 4;
        rremote[0] = 1;
        rremote[1] = 2;
        rremote[2] = 1;
        rremote[3] = 5;
        rremote[4] = 0;
        rremote[5] = 3;
        rremote[6] = 2;
        rremote[7] = 4;
    } else {
        MPI_Abort(comm, 1);
    }
    rootdata = calloc(bs*nroots, sizeof(double));
    leafdata = calloc(bs*nleaves, sizeof(double));

    for ( i = 0; i < nroots*bs; i++ ) {
        leafdata[i] = 10 + 2 * rank;
    }
    for ( i = nroots*bs; i < nleaves*bs; i++ ) {
        leafdata[i] = 3 + 2 * rank;
    }
    for ( i = 0; i < 2; i++ ) {
        ierr = MPI_Type_create_indexed_block(rcount[i], 1, rmine + roffset[i],
                                             unit, &mine[i]);
        ierr = MPI_Type_create_indexed_block(rcount[i], 1, rremote + roffset[i],
                                             unit, &remote[i]);

        ierr = MPI_Type_commit(&mine[i]);
        ierr = MPI_Type_commit(&remote[i]);
    }

    ierr = MPI_Type_get_extent(unit, &lb, &bytes);

    ierr = MPI_Win_create((void *)rootdata, (MPI_Aint)bytes*nroots,
                          bytes, MPI_INFO_NULL, comm, &win);
    ierr = MPI_Win_fence(MPI_MODE_NOPRECEDE, win);
    for (i = 0; i < nranks; i++ ) {
        ierr = MPI_Accumulate((void*)leafdata,1,mine[i],ranks[i],0,1,remote[i],MPI_SUM,win);
    }
    ierr = MPI_Win_fence(MPI_MODE_NOSUCCEED,win);
    ierr = MPI_Win_free(&win);
    for ( i = 0; i < 2; i++ ) {
        ierr = MPI_Type_free(&mine[i]);
        ierr = MPI_Type_free(&remote[i]);
    }
    ierr = MPI_Type_free(&unit);

    if ( rank == 1 ) {
        MPI_Barrier(comm);
    }
    printf("[%d] ", rank);
    for ( i = 0; i < nroots*bs; i++ ) {
        printf("%g ", rootdata[i]);
    }
    printf("\n");
    fflush(stdout);
    if ( rank == 0 ) {
        MPI_Barrier(comm);
    }
    free(rootdata);
    free(leafdata);
    MPI_Finalize();
    return 0;
}