/* set_timer latency test
* John Stultz ([email protected])
* (C) Copyright Linaro 2014
* Licensed under the GPLv2
*
* This test makes sure the set_timer api is correct
*
* To build:
* $ gcc set-timer-lat.c -o set-timer-lat -lrt
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <pthread.h>
#include "../kselftest.h"
#define CLOCK_REALTIME 0
#define CLOCK_MONOTONIC 1
#define CLOCK_PROCESS_CPUTIME_ID 2
#define CLOCK_THREAD_CPUTIME_ID 3
#define CLOCK_MONOTONIC_RAW 4
#define CLOCK_REALTIME_COARSE 5
#define CLOCK_MONOTONIC_COARSE 6
#define CLOCK_BOOTTIME 7
#define CLOCK_REALTIME_ALARM 8
#define CLOCK_BOOTTIME_ALARM 9
#define CLOCK_HWSPECIFIC 10
#define CLOCK_TAI 11
#define NR_CLOCKIDS 12
#define NSEC_PER_SEC 1000000000ULL
#define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */
#define TIMER_SECS 1
int alarmcount;
int clock_id;
struct timespec start_time;
long long max_latency_ns;
int timer_fired_early;
char *clockstring(int clockid)
{
switch (clockid) {
case CLOCK_REALTIME:
return "CLOCK_REALTIME";
case CLOCK_MONOTONIC:
return "CLOCK_MONOTONIC";
case CLOCK_PROCESS_CPUTIME_ID:
return "CLOCK_PROCESS_CPUTIME_ID";
case CLOCK_THREAD_CPUTIME_ID:
return "CLOCK_THREAD_CPUTIME_ID";
case CLOCK_MONOTONIC_RAW:
return "CLOCK_MONOTONIC_RAW";
case CLOCK_REALTIME_COARSE:
return "CLOCK_REALTIME_COARSE";
case CLOCK_MONOTONIC_COARSE:
return "CLOCK_MONOTONIC_COARSE";
case CLOCK_BOOTTIME:
return "CLOCK_BOOTTIME";
case CLOCK_REALTIME_ALARM:
return "CLOCK_REALTIME_ALARM";
case CLOCK_BOOTTIME_ALARM:
return "CLOCK_BOOTTIME_ALARM";
case CLOCK_TAI:
return "CLOCK_TAI";
};
return "UNKNOWN_CLOCKID";
}
long long timespec_sub(struct timespec a, struct timespec b)
{
long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
return ret;
}
void sigalarm(int signo)
{
long long delta_ns;
struct timespec ts;
clock_gettime(clock_id, &ts);
alarmcount++;
delta_ns = timespec_sub(start_time, ts);
delta_ns -= NSEC_PER_SEC * TIMER_SECS * alarmcount;
if (delta_ns < 0)
timer_fired_early = 1;
if (delta_ns > max_latency_ns)
max_latency_ns = delta_ns;
}
void describe_timer(int flags, int interval)
{
printf("%-22s %s %s ",
clockstring(clock_id),
flags ? "ABSTIME":"RELTIME",
interval ? "PERIODIC":"ONE-SHOT");
}
int setup_timer(int clock_id, int flags, int interval, timer_t *tm1)
{
struct sigevent se;
struct itimerspec its1, its2;
int err;
/* Set up timer: */
memset(&se, 0, sizeof(se));
se.sigev_notify = SIGEV_SIGNAL;
se.sigev_signo = SIGRTMAX;
se.sigev_value.sival_int = 0;
max_latency_ns = 0;
alarmcount = 0;
timer_fired_early = 0;
err = timer_create(clock_id, &se, tm1);
if (err) {
if ((clock_id == CLOCK_REALTIME_ALARM) ||
(clock_id == CLOCK_BOOTTIME_ALARM)) {
printf("%-22s %s missing CAP_WAKE_ALARM? : [UNSUPPORTED]\n",
clockstring(clock_id),
flags ? "ABSTIME":"RELTIME");
/* Indicate timer isn't set, so caller doesn't wait */
return 1;
}
printf("%s - timer_create() failed\n", clockstring(clock_id));
return -1;
}
clock_gettime(clock_id, &start_time);
if (flags) {
its1.it_value = start_time;
its1.it_value.tv_sec += TIMER_SECS;
} else {
its1.it_value.tv_sec = TIMER_SECS;
its1.it_value.tv_nsec = 0;
}
its1.it_interval.tv_sec = interval;
its1.it_interval.tv_nsec = 0;
err = timer_settime(*tm1, flags, &its1, &its2);
if (err) {
printf("%s - timer_settime() failed\n", clockstring(clock_id));
return -1;
}
return 0;
}
int check_timer_latency(int flags, int interval)
{
int err = 0;
describe_timer(flags, interval);
printf("timer fired early: %7d : ", timer_fired_early);
if (!timer_fired_early) {
printf("[OK]\n");
} else {
printf("[FAILED]\n");
err = -1;
}
describe_timer(flags, interval);
printf("max latency: %10lld ns : ", max_latency_ns);
if (max_latency_ns < UNRESONABLE_LATENCY) {
printf("[OK]\n");
} else {
printf("[FAILED]\n");
err = -1;
}
return err;
}
int check_alarmcount(int flags, int interval)
{
describe_timer(flags, interval);
printf("count: %19d : ", alarmcount);
if (alarmcount == 1) {
printf("[OK]\n");
return 0;
}
printf("[FAILED]\n");
return -1;
}
int do_timer(int clock_id, int flags)
{
timer_t tm1;
const int interval = TIMER_SECS;
int err;
err = setup_timer(clock_id, flags, interval, &tm1);
/* Unsupported case - return 0 to not fail the test */
if (err)
return err == 1 ? 0 : err;
while (alarmcount < 5)
sleep(1);
timer_delete(tm1);
return check_timer_latency(flags, interval);
}
int do_timer_oneshot(int clock_id, int flags)
{
timer_t tm1;
const int interval = 0;
struct timeval timeout;
int err;
err = setup_timer(clock_id, flags, interval, &tm1);
/* Unsupported case - return 0 to not fail the test */
if (err)
return err == 1 ? 0 : err;
memset(&timeout, 0, sizeof(timeout));
timeout.tv_sec = 5;
do {
err = select(0, NULL, NULL, NULL, &timeout);
} while (err == -1 && errno == EINTR);
timer_delete(tm1);
err = check_timer_latency(flags, interval);
err |= check_alarmcount(flags, interval);
return err;
}
int main(void)
{
struct sigaction act;
int signum = SIGRTMAX;
int ret = 0;
/* Set up signal handler: */
sigfillset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = sigalarm;
sigaction(signum, &act, NULL);
printf("Setting timers for every %i seconds\n", TIMER_SECS);
for (clock_id = 0; clock_id < NR_CLOCKIDS; clock_id++) {
if ((clock_id == CLOCK_PROCESS_CPUTIME_ID) ||
(clock_id == CLOCK_THREAD_CPUTIME_ID) ||
(clock_id == CLOCK_MONOTONIC_RAW) ||
(clock_id == CLOCK_REALTIME_COARSE) ||
(clock_id == CLOCK_MONOTONIC_COARSE) ||
(clock_id == CLOCK_HWSPECIFIC))
continue;
ret |= do_timer(clock_id, TIMER_ABSTIME);
ret |= do_timer(clock_id, 0);
ret |= do_timer_oneshot(clock_id, TIMER_ABSTIME);
ret |= do_timer_oneshot(clock_id, 0);
}
if (ret)
ksft_exit_fail();
ksft_exit_pass();
}
Codebase Browser
linux