#define large 128
#include "mpi.h"
#include <stdio.h>
int main(argc, argv)
int argc;
char **argv;
{
int rank, size, i, sbuf = 1, cnt;
MPI_Init( &argc, &argv );
MPI_Comm_rank( MPI_COMM_WORLD, &rank );
MPI_Comm_size( MPI_COMM_WORLD, &size );
if (rank == 0) {
MPI_Request requests[large];
MPI_Status statuses[large];
int indices[large];
int buf[large];
int j, ndone;
cnt = (size-1)*100;
for (i=1; i<size; i++)
MPI_Irecv( buf+i, 1, MPI_INT, i,
MPI_ANY_TAG, MPI_COMM_WORLD, &requests[i-1] );
while(cnt > 0) {
MPI_Waitsome( size-1, requests, &ndone, indices, statuses );
for (i=0; i<ndone; i++) {
j = indices[i];
printf( "Msg from %d with tag %d\n",
statuses[i].MPI_SOURCE,
statuses[i].MPI_TAG );
MPI_Irecv( buf+j, 1, MPI_INT, j+1,
MPI_ANY_TAG, MPI_COMM_WORLD, &requests[j] );
}
cnt -= ndone;
}
/* We should really cancel the pending receives */
for (i=0; i<size; i++)
MPI_Cancel( &requests[i] );
}
else {
for (i=0; i<100; i++)
MPI_Send( &sbuf, 1, MPI_INT, 0, i, MPI_COMM_WORLD );
}
MPI_Finalize();
return 0;
}