I've been assigned CMR 2728, which is to apply some thread-support
changes to 1.5.x. The trac ticket has amusing language about "needs
testing". I'm not sure what that means. We rather consistently say
that we don't promise anything with regards to true thread support. We
specifically say certain BTLs are off limits and we say things are
poorly tested and can be expected to break. Given all that, what does
it mean to test thread support in OMPI?
One option, specifically in the context of this CMR, is to test only
configuration options and so on. I've done this.
Another possibility is to confirm that simple run-time tests of
multi-threaded message passing succeed. I'm having trouble with this.
Attached is a simple test. It passes over sm but fails over TCP. (One
or both of the initial messages is not received.)
How high should I set my sights on this?
#include <stdio.h>
#include <omp.h>
#include <mpi.h>
#include <string.h> /* memset */
#define N 10000
int main(int argc, char **argv) {
int np, me, buf[2][N], provided;
/* init some stuff */
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
MPI_Comm_size(MPI_COMM_WORLD,&np);
MPI_Comm_rank(MPI_COMM_WORLD,&me);
if ( provided < MPI_THREAD_MULTIPLE ) MPI_Abort(MPI_COMM_WORLD,-1);
/* initialize the buffers */
memset(buf[0], 0, N * sizeof(int));
memset(buf[1], 0, N * sizeof(int));
/* test */
#pragma omp parallel num_threads(2)
{
int id = omp_get_thread_num();
MPI_Status st;
printf("%d %d in parallel region\n", me, id); fflush(stdout);
/* pingpong */
if ( me == 0 ) {
MPI_Send(buf[id],N,MPI_INT,1,7+id,MPI_COMM_WORLD ); printf("%d %d sent\n",me,id); fflush(stdout);
MPI_Recv(buf[id],N,MPI_INT,1,7+id,MPI_COMM_WORLD,&st); printf("%d %d recd\n",me,id); fflush(stdout);
} else {
MPI_Recv(buf[id],N,MPI_INT,0,7+id,MPI_COMM_WORLD,&st); printf("%d %d recd\n",me,id); fflush(stdout);
MPI_Send(buf[id],N,MPI_INT,0,7+id,MPI_COMM_WORLD ); printf("%d %d sent\n",me,id); fflush(stdout);
}
}
MPI_Finalize();
return 0;
}
#!/bin/csh
mpicc -xopenmp -m64 -O5 main.c
mpirun -np 2 --mca btl self,sm ./a.out
mpirun -np 2 --mca btl self,tcp ./a.out
