test code to measure cost of gettimeofday() call.

test_gettimeofday.c

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

int
main(void)
{
  int i, j;
  struct timeval s,e;
  struct timeval t;
  float avg;

  gettimeofday(&s, NULL);
  for (i=0 ; i<1000 ; i++)
    {
      for (j=0 ; j<1000 ; j++)
        {
          gettimeofday(&t, NULL);
        }
    }
  gettimeofday(&e, NULL);

  avg = (float)((e.tv_sec - s.tv_sec) * 1000 * 1000 + (e.tv_usec - s.tv_usec))  / 1000.0 / 1000.0;
  printf("gettimeofday: avg %.2f usec.\n", avg);

  return 0;
}