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];
21 MTest_Init( &argc, &argv );
22 MPI_Comm_rank( MPI_COMM_WORLD, &rank );
23 MPI_Comm_size( MPI_COMM_WORLD, &size );
25 /* A maximum of MAX_PROCESSES processes can participate */
26 if ( size > MAX_PROCESSES ) participants = MAX_PROCESSES;
27 else participants = size;
28 /* while (MAX_PROCESSES % participants) participants--; */
29 if (MAX_PROCESSES % participants) {
30 fprintf( stderr, "Number of processors must divide %d\n",
32 MPI_Abort( MPI_COMM_WORLD, 1 );
34 if ( (rank < participants) ) {
36 /* Determine what rows are my responsibility */
37 int block_size = MAX_PROCESSES / participants;
38 int begin_row = rank * block_size;
39 int end_row = (rank+1) * block_size;
40 int send_count = block_size * MAX_PROCESSES;
42 /* Fill in the displacements and recv_counts */
43 for (i=0; i<participants; i++) {
44 displs[i] = i * block_size * MAX_PROCESSES;
45 recv_counts[i] = send_count;
48 /* Paint my rows my color */
49 for (i=begin_row; i<end_row ;i++)
50 for (j=0; j<MAX_PROCESSES; j++)
51 table[i][j] = rank + 10;
53 /* Gather everybody's result together - sort of like an */
54 /* inefficient allgather */
55 for (i=0; i<participants; i++) {
56 void *sendbuf = (i == rank ? MPI_IN_PLACE : &table[begin_row][0]);
57 MPI_Gatherv(sendbuf, send_count, MPI_INT,
58 &table[0][0], recv_counts, displs, MPI_INT,
63 /* Everybody should have the same table now.
66 Table[i][j] = (i/block_size) + 10;
68 for (i=0; i<MAX_PROCESSES;i++)
69 if ( (table[i][0] - table[i][MAX_PROCESSES-1] !=0) )
71 for (i=0; i<MAX_PROCESSES;i++) {
72 for (j=0; j<MAX_PROCESSES;j++) {
73 if (table[i][j] != (i/block_size) + 10) errors++;
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 return MTestReturnValue( errors );