1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2013 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
10 int main(int argc, char **argv)
12 int i, rank, size, color;
14 MPI_Comm primary[2], secondary[2], tmp;
17 MPI_Init(&argc, &argv);
18 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
19 MPI_Comm_size(MPI_COMM_WORLD, &size);
21 /* Each pair of processes creates a communicator */
22 for (i = 0; i < size; i++) {
24 MPI_Comm_split(MPI_COMM_WORLD, 0, 0, &primary[0]);
25 else if (rank == (i + 1) % size)
26 MPI_Comm_split(MPI_COMM_WORLD, 0, 0, &secondary[0]);
28 MPI_Comm_split(MPI_COMM_WORLD, 1, 0, &tmp);
31 MPI_Barrier(MPI_COMM_WORLD);
34 /* Each pair dups the communicator such that the dups are
35 * overlapping. If this were done with MPI_Comm_dup, this should
37 MPI_Comm_idup(primary[0], &primary[1], &req[0]);
38 MPI_Comm_idup(secondary[0], &secondary[1], &req[1]);
39 MPI_Waitall(2, req, MPI_STATUSES_IGNORE);
41 for (i = 0; i < 2; i++) {
42 MPI_Comm_free(&primary[i]);
43 MPI_Comm_free(&secondary[i]);
47 printf(" No Errors\n");