im tying to the system time my program uses, but all i get is 0, what should i do?PHP Code:double wall_time;
struct rusage ru_start, ru_end;
getrusage(RUSAGE_SELF, &ru_start);
mergesort(args[i], sizeof(original)/sizeof(*original), sizeof(*original),my_cmp); /*my program that need to be measued*/
getrusage(RUSAGE_SELF, &ru_end);
sys_time = ru_end.ru_stime.tv_sec - ru_start.ru_stime.tv_sec;
sys_time += (ru_end.ru_stime.tv_usec - ru_start.ru_stime.tv_usec)/1000000.0;
print("%f",sys_time);
