iticks.3c (2010 09)

iticks(3C) iticks(3C)

The time it takes to execute any given sequence of code, and thus the values reported by these interfaces,

will vary from machine to machine.

The behavior of

iticks_gettimes()

is unspeciﬁed if used with unbound threads.

These interfaces are intended to be used to measure small intervals (fractions of a second). If the value of

the time interval that is stored in an iticks_t object is too large, it will silently overﬂow the

struct

timespec or hrtime_t when it is converted.

EXAMPLES

The following code fragment measures the average cost of

gethostname():

#include <iticks.h>

#include <unistd.h>

#include <stdlib.h>

#include <stdio.h>

#include <time.h>

int main() {

iticks_t begin_user, end_user, total_user = 0;

iticks_t begin_sys, end_sys, total_sys = 0;

iticks_t begin_real, end_real, total_real = 0;

struct timespec user, sys, real;

char *name;

int i, count = 1000;

size_t size = sysconf(_SC_HOST_NAME_MAX) + 1;

name = (char*)malloc(size);

for (i = 0; i < count; i++) {

iticks_gettimes(&begin_user, &begin_sys, NULL, &begin_real);

(void)gethostname(name, size);

iticks_gettimes(&end_user, &end_sys, NULL, &end_real);

total_user += (end_user - begin_user);

total_sys += (end_sys - begin_sys);

total_real += (end_real - begin_real);

}

user = iticks_to_timespec(total_user / count);

sys = iticks_to_timespec(total_sys / count);

real = iticks_to_timespec(total_real / count);

printf("Avg gethostname() time:\n");

printf("\tuser:\t%ld.%09ld\n", user.tv_sec, user.tv_nsec);

printf("\tsys:\t%ld.%09ld\n", sys.tv_sec, sys.tv_nsec);

printf("\treal:\t%ld.%09ld\n", real.tv_sec, real.tv_nsec);

}