demonstrate high-res timers

clocks.c

#include <stdio.h>
#include <time.h>

const int kSamples = 16;

int main(int argc, char* argv[]) {
  struct timespec t[kSamples];
  for (int i = 0; i < kSamples; ++i) {
    clock_gettime(CLOCK_REALTIME, &t[i]);
  }
  printf("0: %ld %ld\n", t[0].tv_sec, t[0].tv_nsec);
  for (int i = 1; i < kSamples; ++i) {
    printf("%ld\n", t[i].tv_nsec - t[i - 1].tv_nsec +
           1000000000L * (t[i].tv_sec - t[i - 1].tv_sec));
  }
}