#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <time.h>
#define NSEMS   2

/* change this per CPU to run between 8 and 12 s*/
const static int maxloop = 10000000; 

main(int argc, char *argv[])
{
    time_t start,last,stop;
    long int i;
    int estimate = 100;
    int sid;
    key_t key;
    ushort vals[NSEMS] = { 0, 0 };

    key = ftok("/tmp",99);
    last=start=time(NULL);
    for (i = 0; i < 1000; ++i) {
        usleep(10);
        last=time(NULL);
        if (last > start) break;
    }
    start=last;
    last = 0;

    for (i = maxloop/8; i < maxloop; i++) {
      if ((sid = semget(key, NSEMS, IPC_CREAT | 0777)) == -1) {
          perror("Can Not Get Semaphore ID");
      }
      if (semctl(sid, NSEMS, GETALL, vals) == -1) {
          perror("Can Not Get Semaphore Values");
      }
    }

/* do the last 1/8th until the second changes.
    If your processor reaches the maxloop before that,
    change the maxloop or the divisor or the "estimate" */

    stop=time(NULL);
    for (i = maxloop - maxloop/8; i < maxloop; ++i) {
      if ( !(i % estimate) ) {
        last=time(NULL);
        if (last > stop) break;
        stop=last;
      }

      /* repeat semaphore opts */
      if ((sid = semget(key, NSEMS, IPC_CREAT | 0777)) == -1) {
          perror("Can Not Get Semaphore ID");
      }
      if (semctl(sid, NSEMS, GETALL, vals) == -1) {
          perror("Can Not Get Semaphore Values");
      }
    }
    stop=last;

    printf("%.2f semop/s (%i/%i) [%d]\n", (double)i/(stop-start), i, stop-start, estimate);
}