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 );
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 /* Gather everybody's result together - sort of like an */
55 /* inefficient allgather */
56 for (i=0; i<participants; i++) {
57 void *sendbuf = (i == rank ? MPI_IN_PLACE : &table[begin_row][0]);
58 MPI_Gatherv(sendbuf, send_count, MPI_INT,
59 &table[0][0], recv_counts, displs, MPI_INT,
64 /* Everybody should have the same table now.
67 Table[i][j] = (i/block_size) + 10;
69 for (i=0; i<MAX_PROCESSES;i++)
70 if ( (table[i][0] - table[i][MAX_PROCESSES-1] !=0) )
72 for (i=0; i<MAX_PROCESSES;i++) {
73 for (j=0; j<MAX_PROCESSES;j++) {
74 if (table[i][j] != (i/block_size) + 10) errors++;
78 /* Print out table if there are any errors */
79 for (i=0; i<MAX_PROCESSES;i++) {
81 for (j=0; j<MAX_PROCESSES; j++)
82 printf(" %d",table[i][j]);
88 MTest_Finalize( errors );
90 return MTestReturnValue( errors );