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/* MPI test program. Reports user namespace and rank, then sends and receives
some simple messages.
Patterned after:
http://en.wikipedia.org/wiki/Message_Passing_Interface#Example_program */
#define _GNU_SOURCE
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <mpi.h>
#define TAG 0
#define MSG_OUT 8675309
void fatal(char * fmt, ...);
int op(int rank, int i);
int rank, rank_ct;
int main(int argc, char ** argv)
{
char hostname[HOST_NAME_MAX+1];
char mpi_version[MPI_MAX_LIBRARY_VERSION_STRING];
int mpi_version_len;
int msg;
MPI_Status mstat;
struct stat st;
stat("/proc/self/ns/user", &st);
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &rank_ct);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (rank == 0) {
MPI_Get_library_version(mpi_version, &mpi_version_len);
printf("%d: MPI version:\n%s\n", rank, mpi_version);
}
gethostname(hostname, HOST_NAME_MAX+1);
printf("%d: init ok %s, %d ranks, userns %lu\n",
rank, hostname, rank_ct, st.st_ino);
fflush(stdout);
if (rank == 0) {
for (int i = 1; i < rank_ct; i++) {
msg = MSG_OUT;
MPI_Send(&msg, 1, MPI_INT, i, TAG, MPI_COMM_WORLD);
msg = 0;
MPI_Recv(&msg, 1, MPI_INT, i, TAG, MPI_COMM_WORLD, &mstat);
if (msg != op(i, MSG_OUT))
fatal("0: expected %d back but got %d", op(i, MSG_OUT), msg);
}
} else {
msg = 0;
MPI_Recv(&msg, 1, MPI_INT, 0, TAG, MPI_COMM_WORLD, &mstat);
if (msg != MSG_OUT)
fatal("%d: expected %d but got %d", rank, MSG_OUT, msg);
msg = op(rank, msg);
MPI_Send(&msg, 1, MPI_INT, 0, TAG, MPI_COMM_WORLD);
}
if (rank == 0)
printf("%d: send/receive ok\n", rank);
MPI_Finalize();
if (rank == 0)
printf("%d: finalize ok\n", rank);
return 0;
}
void fatal(char * fmt, ...)
{
va_list ap;
fprintf(stderr, "rank %d:", rank);
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
fprintf(stderr, "\n");
exit(EXIT_FAILURE);
}
int op(int rank, int i)
{
return i * rank;
}
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