#include<stdio.h>
#include<time.h>
#include <sys/time.h>
#include <sys/resource.h>
// nanosleep to delay process between successive calls to print out time uses timespec structure
int main(int argc, char** argv){
struct timespec curr_time1,curr_time2, sleeptime;
int i,delay,num_iter;
double now1,now2,init;
if (argc!=3) {
fprintf(stderr, "Usage: %s <sleep time..msec><num_iterations>\n", argv[0]);
exit(1);
}
// progname=argv[0];

delay=atoi(argv[1]);
num_iter=atoi(argv[2]);
printf("Delay is %d msec ..num_iter is %d\n",delay,num_iter);
// set up sleeptime struct
sleeptime.tv_sec=0;
while(delay>=1000){ // overflow if >=1sec
sleeptime.tv_sec++;
delay=delay-1000;
}
sleeptime.tv_nsec=delay*1000000;
printf("Sleeptime struct is %d sec: %d nsec\n",sleeptime.tv_sec,sleeptime.tv_nsec);
clock_gettime(CLOCK_REALTIME, &curr_time1);
init=curr_time1.tv_sec + curr_time1.tv_nsec*0.000000001;
for(i=0;i<num_iter;++i)
{
clock_gettime(CLOCK_REALTIME, &curr_time1);
//now=curr_time.tv_sec + curr_time.tv_nsec*0.000000001;
//prev=now;
//wakeup=now+delay*0.001;
nanosleep(&sleeptime,NULL);
clock_gettime(CLOCK_REALTIME, &curr_time2);
now1=curr_time1.tv_sec + curr_time1.tv_nsec*0.000000001;
now2=curr_time2.tv_sec + curr_time2.tv_nsec*0.000000001;
printf("Time is %ld : %ld..slept for %lf
nsec\n",curr_time2.tv_sec,curr_time2.tv_nsec,(now2-now1)*1000000000);
}
printf("Total time taken : actual %lf msec theory(excl. runtime): %d msec\n",(now2-
init)*1000,num_iter*atoi(argv[1]));
return 0;
}