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/*
* Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
*
* Licensed under the terms of the GNU GPL License version 2
*
* Selftests for a few posix timers interface.
*
* Kernel loop code stolen from Steven Rostedt <srostedt@redhat.com>
*/
#include <sys/time.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <time.h>
#include <pthread.h>
#define DELAY 2
#define USECS_PER_SEC 1000000
static volatile int done;
/* Busy loop in userspace to elapse ITIMER_VIRTUAL */
static void user_loop(void)
{
while (!done);
}
/*
* Try to spend as much time as possible in kernelspace
* to elapse ITIMER_PROF.
*/
static void kernel_loop(void)
{
void *addr = sbrk(0);
while (!done) {
brk(addr + 4096);
brk(addr);
}
}
/*
* Sleep until ITIMER_REAL expiration.
*/
static void idle_loop(void)
{
pause();
}
static void sig_handler(int nr)
{
done = 1;
}
/*
* Check the expected timer expiration matches the GTOD elapsed delta since
* we armed the timer. Keep a 0.5 sec error margin due to various jitter.
*/
static int check_diff(struct timeval start, struct timeval end)
{
long long diff;
diff = end.tv_usec - start.tv_usec;
diff += (end.tv_sec - start.tv_sec) * USECS_PER_SEC;
if (abs(diff - DELAY * USECS_PER_SEC) > USECS_PER_SEC / 2) {
printf("Diff too high: %lld..", diff);
return -1;
}
return 0;
}
static int check_itimer(int which)
{
int err;
struct timeval start, end;
struct itimerval val = {
.it_value.tv_sec = DELAY,
};
printf("Check itimer ");
if (which == ITIMER_VIRTUAL)
printf("virtual... ");
else if (which == ITIMER_PROF)
printf("prof... ");
else if (which == ITIMER_REAL)
printf("real... ");
fflush(stdout);
done = 0;
if (which == ITIMER_VIRTUAL)
signal(SIGVTALRM, sig_handler);
else if (which == ITIMER_PROF)
signal(SIGPROF, sig_handler);
else if (which == ITIMER_REAL)
signal(SIGALRM, sig_handler);
err = gettimeofday(&start, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
err = setitimer(which, &val, NULL);
if (err < 0) {
perror("Can't set timer\n");
return -1;
}
if (which == ITIMER_VIRTUAL)
user_loop();
else if (which == ITIMER_PROF)
kernel_loop();
else if (which == ITIMER_REAL)
idle_loop();
gettimeofday(&end, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
if (!check_diff(start, end))
printf("[OK]\n");
else
printf("[FAIL]\n");
return 0;
}
static int check_timer_create(int which)
{
int err;
timer_t id;
struct timeval start, end;
struct itimerspec val = {
.it_value.tv_sec = DELAY,
};
printf("Check timer_create() ");
if (which == CLOCK_THREAD_CPUTIME_ID) {
printf("per thread... ");
} else if (which == CLOCK_PROCESS_CPUTIME_ID) {
printf("per process... ");
}
fflush(stdout);
done = 0;
timer_create(which, NULL, &id);
if (err < 0) {
perror("Can't create timer\n");
return -1;
}
signal(SIGALRM, sig_handler);
err = gettimeofday(&start, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
err = timer_settime(id, 0, &val, NULL);
if (err < 0) {
perror("Can't set timer\n");
return -1;
}
user_loop();
gettimeofday(&end, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
if (!check_diff(start, end))
printf("[OK]\n");
else
printf("[FAIL]\n");
return 0;
}
int main(int argc, char **argv)
{
int err;
printf("Testing posix timers. False negative may happen on CPU execution \n");
printf("based timers if other threads run on the CPU...\n");
if (check_itimer(ITIMER_VIRTUAL) < 0)
return -1;
if (check_itimer(ITIMER_PROF) < 0)
return -1;
if (check_itimer(ITIMER_REAL) < 0)
return -1;
if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0)
return -1;
/*
* It's unfortunately hard to reliably test a timer expiration
* on parallel multithread cputime. We could arm it to expire
* on DELAY * nr_threads, with nr_threads busy looping, then wait
* the normal DELAY since the time is elapsing nr_threads faster.
* But for that we need to ensure we have real physical free CPUs
* to ensure true parallelism. So test only one thread until we
* find a better solution.
*/
if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
return -1;
return 0;
}
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