1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2001 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
10 #define MAX_PROCESSES 10
12 int main(int argc, char **argv)
15 int table[MAX_PROCESSES][MAX_PROCESSES];
18 int displs[MAX_PROCESSES];
19 int recv_counts[MAX_PROCESSES];
22 MTest_Init(&argc, &argv);
23 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
24 MPI_Comm_size(MPI_COMM_WORLD, &size);
26 /* A maximum of MAX_PROCESSES processes can participate */
27 participants = (size > MAX_PROCESSES) ? MAX_PROCESSES : size;
29 if (MAX_PROCESSES % participants) {
30 fprintf(stderr, "Number of processors must divide %d\n", MAX_PROCESSES);
31 MPI_Abort(MPI_COMM_WORLD, 1);
33 MPI_Comm_split(MPI_COMM_WORLD, rank < participants, rank, &test_comm);
35 if (rank < participants) {
37 /* Determine what rows are my responsibility */
38 int block_size = MAX_PROCESSES / participants;
39 int begin_row = rank * block_size;
40 int end_row = (rank + 1) * block_size;
41 int send_count = block_size * MAX_PROCESSES;
43 /* Fill in the displacements and recv_counts */
44 for (i = 0; i < participants; i++) {
45 displs[i] = i * block_size * MAX_PROCESSES;
46 recv_counts[i] = send_count;
49 /* Paint my rows my color */
50 for (i = begin_row; i < end_row; i++)
51 for (j = 0; j < MAX_PROCESSES; j++)
52 table[i][j] = rank + 10;
54 /* Everybody gets the gathered data */
55 if ((char *) &table[begin_row][0] != (char *) table + displs[rank] * sizeof(int))
56 MPI_Allgatherv(&table[begin_row][0], send_count, MPI_INT,
57 &table[0][0], recv_counts, displs, MPI_INT, test_comm);
59 MPI_Allgatherv(MPI_IN_PLACE, send_count, MPI_INT,
60 &table[0][0], recv_counts, displs, MPI_INT, test_comm);
62 /* Everybody should have the same table now.
65 * Table[i][j] = (i/block_size) + 10;
67 for (i = 0; i < MAX_PROCESSES; i++)
68 if ((table[i][0] - table[i][MAX_PROCESSES - 1] != 0))
70 for (i = 0; i < MAX_PROCESSES; i++) {
71 for (j = 0; j < MAX_PROCESSES; j++) {
72 if (table[i][j] != (i / block_size) + 10)
77 /* Print out table if there are any errors */
78 for (i = 0; i < MAX_PROCESSES; i++) {
80 for (j = 0; j < MAX_PROCESSES; j++)
81 printf(" %d", table[i][j]);
87 MTest_Finalize(errors);
89 MPI_Comm_free(&test_comm);
91 return MTestReturnValue(errors);