#define _GNU_SOURCE
#include <sched.h>

#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <string.h>

int main (int argc, char *argv[])
{
int i, procs, count, rank, namelength;
char host[MPI_MAX_PROCESSOR_NAME];
cpu_set_t mask;

MPI_Init(&argc,&argv);

MPI_Comm_size(MPI_COMM_WORLD,&count);
printf("Running with %d (size of comm_world)\n",count);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Get_processor_name(host, &namelength);

sched_getaffinity(0, sizeof(mask), &mask);
procs = sysconf(_SC_NPROCESSORS_ONLN);
count = CPU_COUNT(&mask);
printf("Affinity Procs %d und count %d\n",procs,count);
if (procs != count)
   {
   char cores[1024];
   cores[0] = '\0';
   char buffer[10]; 
   buffer[0] = '\0';
   count=0;
   for (i=0; i<procs; ++i) 
       {
       if (CPU_ISSET(i, &mask))
          {
          snprintf(buffer, 10, "%d", i);
          if (count > 0) strncat(cores, ",", sizeof(buffer));
          strncat(cores, buffer, sizeof(buffer));
          count++;
          }
       }
   printf("MPI rank %2d is running on %s and uses %d of %d cores (%s)\n", rank, host, count, procs, cores);
   }   
else printf("MPI rank %2d is running on %s and uses all %d cores\n", rank, host, procs);

sleep(180);

MPI_Finalize();

return 0;
}