#define MAX_PROCESSES 10
-int main( int argc, char **argv )
+int main(int argc, char **argv)
{
- int rank, size, i,j;
- int table[MAX_PROCESSES][MAX_PROCESSES];
- int errors=0;
- int participants;
- int displs[MAX_PROCESSES];
- int recv_counts[MAX_PROCESSES];
- MPI_Comm test_comm;
+ int rank, size, i, j;
+ int table[MAX_PROCESSES][MAX_PROCESSES];
+ int errors = 0;
+ int participants;
+ int displs[MAX_PROCESSES];
+ int recv_counts[MAX_PROCESSES];
+ MPI_Comm test_comm;
- MTest_Init( &argc, &argv );
- MPI_Comm_rank( MPI_COMM_WORLD, &rank );
- MPI_Comm_size( MPI_COMM_WORLD, &size );
+ MTest_Init(&argc, &argv);
+ MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+ MPI_Comm_size(MPI_COMM_WORLD, &size);
/* A maximum of MAX_PROCESSES processes can participate */
- participants = ( size > MAX_PROCESSES ) ? MAX_PROCESSES : size;
+ participants = (size > MAX_PROCESSES) ? MAX_PROCESSES : size;
if (MAX_PROCESSES % participants) {
- fprintf( stderr, "Number of processors must divide %d\n",
- MAX_PROCESSES );
- MPI_Abort( MPI_COMM_WORLD, 1 );
- }
- MPI_Comm_split(MPI_COMM_WORLD, rank<participants, rank, &test_comm);
+ fprintf(stderr, "Number of processors must divide %d\n", MAX_PROCESSES);
+ MPI_Abort(MPI_COMM_WORLD, 1);
+ }
+ MPI_Comm_split(MPI_COMM_WORLD, rank < participants, rank, &test_comm);
- if ( rank < participants ) {
+ if (rank < participants) {
- /* Determine what rows are my responsibility */
- int block_size = MAX_PROCESSES / participants;
- int begin_row = rank * block_size;
- int end_row = (rank+1) * block_size;
- int send_count = block_size * MAX_PROCESSES;
-
- /* Fill in the displacements and recv_counts */
- for (i=0; i<participants; i++) {
- displs[i] = i * block_size * MAX_PROCESSES;
- recv_counts[i] = send_count;
- }
+ /* Determine what rows are my responsibility */
+ int block_size = MAX_PROCESSES / participants;
+ int begin_row = rank * block_size;
+ int end_row = (rank + 1) * block_size;
+ int send_count = block_size * MAX_PROCESSES;
- /* Paint my rows my color */
- for (i=begin_row; i<end_row ;i++)
- for (j=0; j<MAX_PROCESSES; j++)
- table[i][j] = rank + 10;
-
- /* Everybody gets the gathered data */
- MPI_Allgatherv(&table[begin_row][0], send_count, MPI_INT,
- &table[0][0], recv_counts, displs,
- MPI_INT, test_comm);
+ /* Fill in the displacements and recv_counts */
+ for (i = 0; i < participants; i++) {
+ displs[i] = i * block_size * MAX_PROCESSES;
+ recv_counts[i] = send_count;
+ }
- /* Everybody should have the same table now.
+ /* Paint my rows my color */
+ for (i = begin_row; i < end_row; i++)
+ for (j = 0; j < MAX_PROCESSES; j++)
+ table[i][j] = rank + 10;
- The entries are:
- Table[i][j] = (i/block_size) + 10;
- */
- for (i=0; i<MAX_PROCESSES;i++)
- if ( (table[i][0] - table[i][MAX_PROCESSES-1] !=0) )
- errors++;
- for (i=0; i<MAX_PROCESSES;i++) {
- for (j=0; j<MAX_PROCESSES;j++) {
- if (table[i][j] != (i/block_size) + 10) errors++;
- }
- }
- if (errors) {
- /* Print out table if there are any errors */
- for (i=0; i<MAX_PROCESSES;i++) {
- printf("\n");
- for (j=0; j<MAX_PROCESSES; j++)
- printf(" %d",table[i][j]);
- }
- printf("\n");
- }
- }
+ /* Everybody gets the gathered data */
+ if ((char *) &table[begin_row][0] != (char *) table + displs[rank] * sizeof(int))
+ MPI_Allgatherv(&table[begin_row][0], send_count, MPI_INT,
+ &table[0][0], recv_counts, displs, MPI_INT, test_comm);
+ else
+ MPI_Allgatherv(MPI_IN_PLACE, send_count, MPI_INT,
+ &table[0][0], recv_counts, displs, MPI_INT, test_comm);
- MTest_Finalize( errors );
+ /* Everybody should have the same table now.
+ *
+ * The entries are:
+ * Table[i][j] = (i/block_size) + 10;
+ */
+ for (i = 0; i < MAX_PROCESSES; i++)
+ if ((table[i][0] - table[i][MAX_PROCESSES - 1] != 0))
+ errors++;
+ for (i = 0; i < MAX_PROCESSES; i++) {
+ for (j = 0; j < MAX_PROCESSES; j++) {
+ if (table[i][j] != (i / block_size) + 10)
+ errors++;
+ }
+ }
+ if (errors) {
+ /* Print out table if there are any errors */
+ for (i = 0; i < MAX_PROCESSES; i++) {
+ printf("\n");
+ for (j = 0; j < MAX_PROCESSES; j++)
+ printf(" %d", table[i][j]);
+ }
+ printf("\n");
+ }
+ }
+
+ MTest_Finalize(errors);
MPI_Comm_free(&test_comm);
MPI_Finalize();
- return MTestReturnValue( errors );
+ return MTestReturnValue(errors);
}