// Build with -lrt

#define _POSIX_C_SOURCE 200112L

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

int main() {
        struct timespec tv_start, tv_end;
        struct timeval tv_tmp;
        int count = 1 * 1000 * 1000 * 50;
        clockid_t clockid;
        int rv = clock_getcpuclockid(0, &clockid);

        if (rv) {
                perror("clock_getcpuclockid");
                return 1;
        }

        clock_gettime(clockid, &tv_start);
        for (int i = 0; i < count; i++)
                gettimeofday(&tv_tmp, NULL);
        clock_gettime(clockid, &tv_end);

        long long diff = (long long)(tv_end.tv_sec - tv_start.tv_sec)*(1*1000*1000*1000);
        diff += (tv_end.tv_nsec - tv_start.tv_nsec);

        printf("%d cycles in %lld ns = %f ns/cycle\n", count, diff, (double)diff / (double)count);
        return 0;
}