1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2011 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
7 /* USE_STRICT_MPI may be defined in mpitestconf.h */
8 #include "mpitestconf.h"
14 int main(int argc, char *argv[])
16 int size, rank, i, *excl;
17 MPI_Group world_group, even_group;
18 MPI_Comm __attribute__((unused)) even_comm;
20 MPI_Init(&argc, &argv);
22 MPI_Comm_size(MPI_COMM_WORLD, &size);
23 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
26 fprintf(stderr, "this program requires a multiple of 2 number of processes\n");
27 MPI_Abort(MPI_COMM_WORLD, 1);
30 excl = malloc((size / 2) * sizeof(int));
33 /* exclude the odd ranks */
34 for (i = 0; i < size / 2; i++)
35 excl[i] = (2 * i) + 1;
37 /* Create some groups */
38 MPI_Comm_group(MPI_COMM_WORLD, &world_group);
39 MPI_Group_excl(world_group, size / 2, excl, &even_group);
40 MPI_Group_free(&world_group);
42 #if !defined(USE_STRICT_MPI) && defined(MPICH)
44 /* Even processes create a group for themselves */
45 MPI_Comm_create_group(MPI_COMM_WORLD, even_group, 0, &even_comm);
46 MPI_Barrier(even_comm);
47 MPI_Comm_free(&even_comm);
49 #endif /* USE_STRICT_MPI */
51 MPI_Group_free(&even_group);
52 MPI_Barrier(MPI_COMM_WORLD);
55 printf(" No errors\n");