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selftests: add basic posix timers selftests
Add some initial basic tests on a few posix timers interface such as setitimer() and timer_settime(). These simply check that expiration happens in a reasonable timeframe after expected elapsed clock time (user time, user + system time, real time, ...). This is helpful for finding basic breakages while hacking on this subsystem. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Olivier Langlois <olivier@trillion01.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -6,6 +6,7 @@ TARGETS += memory-hotplug
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TARGETS += mqueue
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TARGETS += net
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TARGETS += ptrace
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TARGETS += timers
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TARGETS += vm
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all:
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8
tools/testing/selftests/timers/Makefile
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8
tools/testing/selftests/timers/Makefile
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@ -0,0 +1,8 @@
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all:
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gcc posix_timers.c -o posix_timers -lrt
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run_tests: all
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./posix_timers
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clean:
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rm -f ./posix_timers
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221
tools/testing/selftests/timers/posix_timers.c
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221
tools/testing/selftests/timers/posix_timers.c
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@ -0,0 +1,221 @@
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/*
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* Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
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*
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* Licensed under the terms of the GNU GPL License version 2
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*
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* Selftests for a few posix timers interface.
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*
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* Kernel loop code stolen from Steven Rostedt <srostedt@redhat.com>
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*/
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#include <sys/time.h>
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#include <stdio.h>
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#include <signal.h>
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#include <unistd.h>
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#include <time.h>
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#include <pthread.h>
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#define DELAY 2
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#define USECS_PER_SEC 1000000
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static volatile int done;
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/* Busy loop in userspace to elapse ITIMER_VIRTUAL */
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static void user_loop(void)
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{
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while (!done);
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}
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/*
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* Try to spend as much time as possible in kernelspace
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* to elapse ITIMER_PROF.
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*/
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static void kernel_loop(void)
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{
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void *addr = sbrk(0);
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while (!done) {
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brk(addr + 4096);
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brk(addr);
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}
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}
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/*
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* Sleep until ITIMER_REAL expiration.
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*/
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static void idle_loop(void)
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{
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pause();
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}
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static void sig_handler(int nr)
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{
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done = 1;
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}
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/*
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* Check the expected timer expiration matches the GTOD elapsed delta since
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* we armed the timer. Keep a 0.5 sec error margin due to various jitter.
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*/
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static int check_diff(struct timeval start, struct timeval end)
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{
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long long diff;
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diff = end.tv_usec - start.tv_usec;
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diff += (end.tv_sec - start.tv_sec) * USECS_PER_SEC;
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if (abs(diff - DELAY * USECS_PER_SEC) > USECS_PER_SEC / 2) {
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printf("Diff too high: %lld..", diff);
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return -1;
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}
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return 0;
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}
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static int check_itimer(int which)
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{
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int err;
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struct timeval start, end;
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struct itimerval val = {
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.it_value.tv_sec = DELAY,
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};
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printf("Check itimer ");
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if (which == ITIMER_VIRTUAL)
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printf("virtual... ");
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else if (which == ITIMER_PROF)
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printf("prof... ");
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else if (which == ITIMER_REAL)
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printf("real... ");
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fflush(stdout);
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done = 0;
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if (which == ITIMER_VIRTUAL)
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signal(SIGVTALRM, sig_handler);
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else if (which == ITIMER_PROF)
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signal(SIGPROF, sig_handler);
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else if (which == ITIMER_REAL)
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signal(SIGALRM, sig_handler);
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err = gettimeofday(&start, NULL);
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if (err < 0) {
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perror("Can't call gettimeofday()\n");
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return -1;
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}
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err = setitimer(which, &val, NULL);
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if (err < 0) {
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perror("Can't set timer\n");
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return -1;
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}
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if (which == ITIMER_VIRTUAL)
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user_loop();
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else if (which == ITIMER_PROF)
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kernel_loop();
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else if (which == ITIMER_REAL)
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idle_loop();
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gettimeofday(&end, NULL);
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if (err < 0) {
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perror("Can't call gettimeofday()\n");
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return -1;
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}
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if (!check_diff(start, end))
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printf("[OK]\n");
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else
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printf("[FAIL]\n");
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return 0;
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}
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static int check_timer_create(int which)
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{
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int err;
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timer_t id;
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struct timeval start, end;
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struct itimerspec val = {
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.it_value.tv_sec = DELAY,
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};
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printf("Check timer_create() ");
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if (which == CLOCK_THREAD_CPUTIME_ID) {
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printf("per thread... ");
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} else if (which == CLOCK_PROCESS_CPUTIME_ID) {
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printf("per process... ");
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}
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fflush(stdout);
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done = 0;
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timer_create(which, NULL, &id);
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if (err < 0) {
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perror("Can't create timer\n");
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return -1;
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}
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signal(SIGALRM, sig_handler);
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err = gettimeofday(&start, NULL);
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if (err < 0) {
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perror("Can't call gettimeofday()\n");
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return -1;
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}
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err = timer_settime(id, 0, &val, NULL);
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if (err < 0) {
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perror("Can't set timer\n");
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return -1;
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}
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user_loop();
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gettimeofday(&end, NULL);
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if (err < 0) {
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perror("Can't call gettimeofday()\n");
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return -1;
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}
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if (!check_diff(start, end))
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printf("[OK]\n");
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else
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printf("[FAIL]\n");
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return 0;
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}
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int main(int argc, char **argv)
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{
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int err;
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printf("Testing posix timers. False negative may happen on CPU execution \n");
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printf("based timers if other threads run on the CPU...\n");
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if (check_itimer(ITIMER_VIRTUAL) < 0)
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return -1;
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if (check_itimer(ITIMER_PROF) < 0)
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return -1;
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if (check_itimer(ITIMER_REAL) < 0)
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return -1;
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if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0)
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return -1;
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/*
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* It's unfortunately hard to reliably test a timer expiration
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* on parallel multithread cputime. We could arm it to expire
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* on DELAY * nr_threads, with nr_threads busy looping, then wait
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* the normal DELAY since the time is elapsing nr_threads faster.
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* But for that we need to ensure we have real physical free CPUs
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* to ensure true parallelism. So test only one thread until we
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* find a better solution.
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*/
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if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
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return -1;
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return 0;
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}
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