diff options
Diffstat (limited to 'tools/testing/selftests/timers/posix_timers.c')
| -rw-r--r-- | tools/testing/selftests/timers/posix_timers.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/tools/testing/selftests/timers/posix_timers.c b/tools/testing/selftests/timers/posix_timers.c new file mode 100644 index 000000000..0ba500056 --- /dev/null +++ b/tools/testing/selftests/timers/posix_timers.c @@ -0,0 +1,221 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com> + * + * 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> + +#include "../kselftest.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); + int err = 0; + + while (!done && !err) { + err = brk(addr + 4096); + err |= 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(); + + err = 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; + err = 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(); + + err = 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) +{ + 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 ksft_exit_fail(); + + if (check_itimer(ITIMER_PROF) < 0) + return ksft_exit_fail(); + + if (check_itimer(ITIMER_REAL) < 0) + return ksft_exit_fail(); + + if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0) + return ksft_exit_fail(); + + /* + * 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 ksft_exit_fail(); + + return ksft_exit_pass(); +} |