Timing loop direction and speed

test.c

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


int getTime() {
   struct rusage r;

   if(getrusage(RUSAGE_SELF, &r)!=0) {perror("FAIL RUSAGE");}
   
   double u = (r.ru_utime.tv_sec * 1000) + (r.ru_utime.tv_usec/1000.0);
   double s = (r.ru_stime.tv_sec * 1000) + (r.ru_stime.tv_usec/1000.0);

   printf("-----------> u %lf, s %lf\n", u, s);
   return u + s;
}

int main(){ 
   int j=0;
   int i=0;
   int k=0;

   double t1 = getTime();

   for(k=0; k<10;k++) {
   for(i=1000000000;i>=0;i--) {
      j = i;
   }
   }

   double t2 = getTime();

   printf ("t1 %lf, t2 %lf, diff %lf\n", t1, t2, t2-t1);

   return 0;
}