1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2009 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
12 #define MAX_LOG_WSIZE 31
15 int main(int argc, char *argv[])
18 MPI_Comm comm, newcomm[MAX_LOOP];
19 int wsize, wrank, range[1][3], errs = 0;
20 double t[MAX_LOG_WSIZE], tf;
21 int maxi, i, k, ts, gsize[MAX_LOG_WSIZE];
23 MTest_Init(&argc, &argv);
25 MPI_Comm_size(MPI_COMM_WORLD, &wsize);
26 MPI_Comm_rank(MPI_COMM_WORLD, &wrank);
29 MTestPrintfMsg(1, "size\ttime\n");
31 MPI_Comm_group(MPI_COMM_WORLD, &gworld);
33 comm = MPI_COMM_WORLD;
34 for (i = 0; ts <= wsize; i++, ts = ts + ts) {
35 /* Create some groups with at most ts members */
39 MPI_Group_range_incl(gworld, 1, range, &g);
41 MPI_Barrier(MPI_COMM_WORLD);
43 for (k = 0; k < MAX_LOOP; k++)
44 MPI_Comm_create(comm, g, &newcomm[k]);
45 tf = MPI_Wtime() - tf;
46 MPI_Allreduce(&tf, &t[i], 1, MPI_DOUBLE, MPI_MAX, MPI_COMM_WORLD);
47 t[i] = t[i] / MAX_LOOP;
50 MTestPrintfMsg(1, "%d\t%e\n", ts, t[i]);
52 if (newcomm[0] != MPI_COMM_NULL)
53 for (k = 0; k < MAX_LOOP; k++)
54 MPI_Comm_free(&newcomm[k]);
56 MPI_Group_free(&gworld);
59 /* The cost should be linear or at worst ts*log(ts).
60 * We can check this in a number of ways.
63 for (i = 4; i <= maxi; i++) {
66 rdiff = (t[i] - t[i - 1]) / t[i];
70 "Relative difference between group of size %d and %d is %e exceeds 4\n",
71 gsize[i - 1], gsize[i], rdiff);