Tests overhead of nanosleep in a Unix system

test_nanosleep.c

// Tests overhead of nanosleep in a Unix system
// Compile it like this:
//   gcc -o test_nanosleep test_nanosleep -lrt
// Tested in Solaris

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

int main()
{
   struct timespec tim, tim2;
   tim.tv_sec = 0;
   tim.tv_nsec = 1e6;

   struct timeval start_time;
   struct timeval end_time;

   gettimeofday(&start_time, NULL);

   if(nanosleep(&tim , &tim2) < 0 )
   {
      printf("Nano sleep system call failed \n");
      return -1;
   }

   gettimeofday(&end_time, NULL);

   // Time elapsed in microseconds
   int elapsed = (end_time.tv_sec - start_time.tv_sec)*1000000 + (end_time.tv_usec - start_time.tv_usec);

   printf("Time elapsed %.3fms\n", elapsed/1000.0);

   return 0;
}