
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sched.h>
#include <mpi.h>
#include <omp.h>
/* Borrowed from util-linux-2.13-pre7/schedutils/taskset.c */
static char *cpuset_to_cstr(cpu_set_t *mask, char *str)
{
char *ptr = str;
int i, j, entry_made = 0;
for (i = 0; i < CPU_SETSIZE; i++) {
if (CPU_ISSET(i, mask)) {
int run = 0;
entry_made = 1;
for (j = i + 1; j < CPU_SETSIZE; j++) {
if (CPU_ISSET(j, mask)) run++;
else break;
}
if (!run)
sprintf(ptr, "%d,", i);
else if (run == 1) {
sprintf(ptr, "%d,%d,", i, i + 1);
i++;
} else {
sprintf(ptr, "%d-%d,", i, i + run);
i += run;
}
while (*ptr != 0) ptr++;
}
}
ptr -= entry_made;
*ptr = 0;
return(str);
}
int main(int argc, char *argv[])
{
int rank, thread;
cpu_set_t coremask;
char clbuf[7 * CPU_SETSIZE], hnbuf[64];
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
memset(clbuf, 0, sizeof(clbuf));
memset(hnbuf, 0, sizeof(hnbuf));
(void)gethostname(hnbuf, sizeof(hnbuf));
#pragma omp parallel private(thread, coremask, clbuf)
{
thread = omp_get_thread_num();
(void)sched_getaffinity(0, sizeof(coremask), &coremask);
cpuset_to_cstr(&coremask, clbuf);
#pragma omp barrier
printf("Hello from rank %d, thread %d, on %s. (core affinity = %s)\n",
rank, thread, hnbuf, clbuf);
}
MPI_Finalize();
return(0);
}
