/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *  (C) 2011 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

/*

 * Test of reduce scatter block with large data on an intercommunicator

 * (needed in MPICH to trigger the long-data algorithm)

 *

 * Each processor contributes its rank + the index to the reduction,

 * then receives the ith sum

 *

 * Can be called with any number of processors.

 */

#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include "mpitest.h"

int main(int argc, char **argv)

{

    int errs = 0;

    int size, rsize, rank, i;

    int recvcount,              /* Each process receives this much data */

     sendcount,                 /* Each process contributes this much data */

     basecount;                 /* Unit of elements - basecount *rsize is recvcount,

                                 * etc. */

    int isLeftGroup;

    long long *sendbuf, *recvbuf;

    long long sumval;

    MPI_Comm comm;

    MTest_Init(&argc, &argv);

    comm = MPI_COMM_WORLD;

    basecount = 1024;

    while (MTestGetIntercomm(&comm, &isLeftGroup, 2)) {

        if (comm == MPI_COMM_NULL)

            continue;

        MPI_Comm_remote_size(comm, &rsize);

        MPI_Comm_size(comm, &size);

        MPI_Comm_rank(comm, &rank;;

        if (0) {

            printf("[%d] %s (%d,%d) remote %d\n", rank, isLeftGroup ? "L" : "R", rank, size, rsize);

        }

        recvcount = basecount * rsize;

        sendcount = basecount * rsize * size;

        sendbuf = (long long *) malloc(sendcount * sizeof(long long));

        if (!sendbuf) {

            fprintf(stderr, "Could not allocate %d ints for sendbuf\n", sendcount);

            MPI_Abort(MPI_COMM_WORLD, 1);

        }

        for (i = 0; i < sendcount; i++) {

            sendbuf[i] = (long long) (rank * sendcount + i);

        }

        recvbuf = (long long *) malloc(recvcount * sizeof(long long));

        if (!recvbuf) {

            fprintf(stderr, "Could not allocate %d ints for recvbuf\n", recvcount);

            MPI_Abort(MPI_COMM_WORLD, 1);

        }

        for (i = 0; i < recvcount; i++) {

            recvbuf[i] = (long long) (-i);

        }

        MPI_Reduce_scatter_block(sendbuf, recvbuf, recvcount, MPI_LONG_LONG, MPI_SUM, comm);

        /* Check received data */

        for (i = 0; i < recvcount; i++) {

            sumval = (long long) (sendcount) * (long long) ((rsize * (rsize - 1)) / 2) +

                (long long) (i + rank * rsize * basecount) * (long long) rsize;

            if (recvbuf[i] != sumval) {

                errs++;

                if (errs < 4) {

                    fprintf(stdout, "Did not get expected value for reduce scatter\n");

                    fprintf(stdout, "[%d] %s recvbuf[%d] = %lld, expected %lld\n",

                            rank, isLeftGroup ? "L" : "R", i, recvbuf[i], sumval);

                }

            }

        }

        free(sendbuf);

        free(recvbuf);

        MTestFreeComm(&comm);

    }

    MTest_Finalize(errs);

    return MTestReturnValue(errs);

}