From e797203fb3ba8c0ed2f4a8800d626c9d54fedfbf Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Thu, 16 Mar 2023 13:30:28 +0100 Subject: selftests/timers/posix_timers: Test delivery of signals across threads Test that POSIX timers using CLOCK_PROCESS_CPUTIME_ID eventually deliver a signal to all running threads. This effectively tests that the kernel doesn't prefer any one thread (or subset of threads) for signal delivery. Signed-off-by: Dmitry Vyukov Signed-off-by: Marco Elver Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230316123028.2890338-2-elver@google.com --- tools/testing/selftests/timers/posix_timers.c | 77 +++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) (limited to 'tools/testing') diff --git a/tools/testing/selftests/timers/posix_timers.c b/tools/testing/selftests/timers/posix_timers.c index 0ba500056e63..8a17c0e8d82b 100644 --- a/tools/testing/selftests/timers/posix_timers.c +++ b/tools/testing/selftests/timers/posix_timers.c @@ -188,6 +188,80 @@ static int check_timer_create(int which) return 0; } +int remain; +__thread int got_signal; + +static void *distribution_thread(void *arg) +{ + while (__atomic_load_n(&remain, __ATOMIC_RELAXED)); + return NULL; +} + +static void distribution_handler(int nr) +{ + if (!__atomic_exchange_n(&got_signal, 1, __ATOMIC_RELAXED)) + __atomic_fetch_sub(&remain, 1, __ATOMIC_RELAXED); +} + +/* + * Test that all running threads _eventually_ receive CLOCK_PROCESS_CPUTIME_ID + * timer signals. This primarily tests that the kernel does not favour any one. + */ +static int check_timer_distribution(void) +{ + int err, i; + timer_t id; + const int nthreads = 10; + pthread_t threads[nthreads]; + struct itimerspec val = { + .it_value.tv_sec = 0, + .it_value.tv_nsec = 1000 * 1000, + .it_interval.tv_sec = 0, + .it_interval.tv_nsec = 1000 * 1000, + }; + + printf("Check timer_create() per process signal distribution... "); + fflush(stdout); + + remain = nthreads + 1; /* worker threads + this thread */ + signal(SIGALRM, distribution_handler); + err = timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); + if (err < 0) { + perror("Can't create timer\n"); + return -1; + } + err = timer_settime(id, 0, &val, NULL); + if (err < 0) { + perror("Can't set timer\n"); + return -1; + } + + for (i = 0; i < nthreads; i++) { + if (pthread_create(&threads[i], NULL, distribution_thread, NULL)) { + perror("Can't create thread\n"); + return -1; + } + } + + /* Wait for all threads to receive the signal. */ + while (__atomic_load_n(&remain, __ATOMIC_RELAXED)); + + for (i = 0; i < nthreads; i++) { + if (pthread_join(threads[i], NULL)) { + perror("Can't join thread\n"); + return -1; + } + } + + if (timer_delete(id)) { + perror("Can't delete timer\n"); + return -1; + } + + printf("[OK]\n"); + return 0; +} + int main(int argc, char **argv) { printf("Testing posix timers. False negative may happen on CPU execution \n"); @@ -217,5 +291,8 @@ int main(int argc, char **argv) if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0) return ksft_exit_fail(); + if (check_timer_distribution() < 0) + return ksft_exit_fail(); + return ksft_exit_pass(); } -- cgit v1.2.3 From 270b2a679ea7be1ee2d84ea67751fb1ab15bcb20 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 22 Feb 2023 15:46:48 +0100 Subject: selftests/proc: Remove idle time monotonicity assertions Due to broken iowait task counting design (cf: comments above get_cpu_idle_time_us() and nr_iowait()), it is not possible to provide the guarantee that /proc/stat or /proc/uptime display monotonic idle time values. Remove the assertions that verify the related wrong assumption so that testers and maintainers don't spend more time on that. Reported-by: Yu Liao Reported-by: Thomas Gleixner Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230222144649.624380-8-frederic@kernel.org --- tools/testing/selftests/proc/proc-uptime-001.c | 12 ++++++------ tools/testing/selftests/proc/proc-uptime-002.c | 13 ++++++------- tools/testing/selftests/proc/proc-uptime.h | 16 ++-------------- 3 files changed, 14 insertions(+), 27 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/proc/proc-uptime-001.c b/tools/testing/selftests/proc/proc-uptime-001.c index 781f7a50fc3f..35bddd9dd60b 100644 --- a/tools/testing/selftests/proc/proc-uptime-001.c +++ b/tools/testing/selftests/proc/proc-uptime-001.c @@ -13,7 +13,9 @@ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ -// Test that values in /proc/uptime increment monotonically. +// Test that boottime value in /proc/uptime increments monotonically. +// We don't test idle time monotonicity due to broken iowait task +// counting, cf: comment above get_cpu_idle_time_us() #undef NDEBUG #include #include @@ -25,20 +27,18 @@ int main(void) { - uint64_t start, u0, u1, i0, i1; + uint64_t start, u0, u1; int fd; fd = open("/proc/uptime", O_RDONLY); assert(fd >= 0); - proc_uptime(fd, &u0, &i0); + u0 = proc_uptime(fd); start = u0; do { - proc_uptime(fd, &u1, &i1); + u1 = proc_uptime(fd); assert(u1 >= u0); - assert(i1 >= i0); u0 = u1; - i0 = i1; } while (u1 - start < 100); return 0; diff --git a/tools/testing/selftests/proc/proc-uptime-002.c b/tools/testing/selftests/proc/proc-uptime-002.c index 7d0aa22bdc12..7ad79d5eaa84 100644 --- a/tools/testing/selftests/proc/proc-uptime-002.c +++ b/tools/testing/selftests/proc/proc-uptime-002.c @@ -13,8 +13,9 @@ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ -// Test that values in /proc/uptime increment monotonically -// while shifting across CPUs. +// Test that boottime value in /proc/uptime increments monotonically +// while shifting across CPUs. We don't test idle time monotonicity +// due to broken iowait task counting, cf: comment above get_cpu_idle_time_us() #undef NDEBUG #include #include @@ -45,7 +46,7 @@ int main(void) unsigned int len; unsigned long *m; unsigned int cpu; - uint64_t u0, u1, i0, i1; + uint64_t u0, u1; int fd; /* find out "nr_cpu_ids" */ @@ -60,7 +61,7 @@ int main(void) fd = open("/proc/uptime", O_RDONLY); assert(fd >= 0); - proc_uptime(fd, &u0, &i0); + u0 = proc_uptime(fd); for (cpu = 0; cpu < len * 8; cpu++) { memset(m, 0, len); m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long))); @@ -68,11 +69,9 @@ int main(void) /* CPU might not exist, ignore error */ sys_sched_setaffinity(0, len, m); - proc_uptime(fd, &u1, &i1); + u1 = proc_uptime(fd); assert(u1 >= u0); - assert(i1 >= i0); u0 = u1; - i0 = i1; } return 0; diff --git a/tools/testing/selftests/proc/proc-uptime.h b/tools/testing/selftests/proc/proc-uptime.h index dc6a42b1d6b0..ca55abeb0ccc 100644 --- a/tools/testing/selftests/proc/proc-uptime.h +++ b/tools/testing/selftests/proc/proc-uptime.h @@ -22,7 +22,7 @@ #include "proc.h" -static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle) +static uint64_t proc_uptime(int fd) { uint64_t val1, val2; char buf[64], *p; @@ -43,18 +43,6 @@ static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle) assert(p[3] == ' '); val2 = (p[1] - '0') * 10 + p[2] - '0'; - *uptime = val1 * 100 + val2; - p += 4; - - val1 = xstrtoull(p, &p); - assert(p[0] == '.'); - assert('0' <= p[1] && p[1] <= '9'); - assert('0' <= p[2] && p[2] <= '9'); - assert(p[3] == '\n'); - - val2 = (p[1] - '0') * 10 + p[2] - '0'; - *idle = val1 * 100 + val2; - - assert(p + 4 == buf + rv); + return val1 * 100 + val2; } -- cgit v1.2.3 From 263dda24fff0957f6b0a9abde2809122f7f0fad8 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 22 Feb 2023 15:46:49 +0100 Subject: selftests/proc: Assert clock_gettime(CLOCK_BOOTTIME) VS /proc/uptime monotonicity The first field of /proc/uptime relies on the CLOCK_BOOTTIME clock which can also be fetched from clock_gettime() API. Improve the test coverage while verifying the monotonicity of CLOCK_BOOTTIME accross both interfaces. Suggested-by: Thomas Gleixner Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230222144649.624380-9-frederic@kernel.org --- tools/testing/selftests/proc/proc-uptime-001.c | 21 +++++++++++++++++---- tools/testing/selftests/proc/proc-uptime-002.c | 22 ++++++++++++++++++---- tools/testing/selftests/proc/proc-uptime.h | 12 ++++++++++++ 3 files changed, 47 insertions(+), 8 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/proc/proc-uptime-001.c b/tools/testing/selftests/proc/proc-uptime-001.c index 35bddd9dd60b..f335eec5067e 100644 --- a/tools/testing/selftests/proc/proc-uptime-001.c +++ b/tools/testing/selftests/proc/proc-uptime-001.c @@ -13,9 +13,9 @@ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ -// Test that boottime value in /proc/uptime increments monotonically. -// We don't test idle time monotonicity due to broken iowait task -// counting, cf: comment above get_cpu_idle_time_us() +// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment +// monotonically. We don't test idle time monotonicity due to broken iowait +// task counting, cf: comment above get_cpu_idle_time_us() #undef NDEBUG #include #include @@ -27,7 +27,7 @@ int main(void) { - uint64_t start, u0, u1; + uint64_t start, u0, u1, c0, c1; int fd; fd = open("/proc/uptime", O_RDONLY); @@ -35,10 +35,23 @@ int main(void) u0 = proc_uptime(fd); start = u0; + c0 = clock_boottime(); + do { u1 = proc_uptime(fd); + c1 = clock_boottime(); + + /* Is /proc/uptime monotonic ? */ assert(u1 >= u0); + + /* Is CLOCK_BOOTTIME monotonic ? */ + assert(c1 >= c0); + + /* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */ + assert(c0 >= u0); + u0 = u1; + c0 = c1; } while (u1 - start < 100); return 0; diff --git a/tools/testing/selftests/proc/proc-uptime-002.c b/tools/testing/selftests/proc/proc-uptime-002.c index 7ad79d5eaa84..ae453daa96c1 100644 --- a/tools/testing/selftests/proc/proc-uptime-002.c +++ b/tools/testing/selftests/proc/proc-uptime-002.c @@ -13,9 +13,10 @@ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ -// Test that boottime value in /proc/uptime increments monotonically -// while shifting across CPUs. We don't test idle time monotonicity -// due to broken iowait task counting, cf: comment above get_cpu_idle_time_us() +// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment +// monotonically while shifting across CPUs. We don't test idle time +// monotonicity due to broken iowait task counting, cf: comment above +// get_cpu_idle_time_us() #undef NDEBUG #include #include @@ -43,10 +44,10 @@ static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned lo int main(void) { + uint64_t u0, u1, c0, c1; unsigned int len; unsigned long *m; unsigned int cpu; - uint64_t u0, u1; int fd; /* find out "nr_cpu_ids" */ @@ -62,6 +63,8 @@ int main(void) assert(fd >= 0); u0 = proc_uptime(fd); + c0 = clock_boottime(); + for (cpu = 0; cpu < len * 8; cpu++) { memset(m, 0, len); m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long))); @@ -70,8 +73,19 @@ int main(void) sys_sched_setaffinity(0, len, m); u1 = proc_uptime(fd); + c1 = clock_boottime(); + + /* Is /proc/uptime monotonic ? */ assert(u1 >= u0); + + /* Is CLOCK_BOOTTIME monotonic ? */ + assert(c1 >= c0); + + /* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */ + assert(c0 >= u0); + u0 = u1; + c0 = c1; } return 0; diff --git a/tools/testing/selftests/proc/proc-uptime.h b/tools/testing/selftests/proc/proc-uptime.h index ca55abeb0ccc..730cce4a3d73 100644 --- a/tools/testing/selftests/proc/proc-uptime.h +++ b/tools/testing/selftests/proc/proc-uptime.h @@ -19,9 +19,21 @@ #include #include #include +#include #include "proc.h" +static uint64_t clock_boottime(void) +{ + struct timespec ts; + int err; + + err = clock_gettime(CLOCK_BOOTTIME, &ts); + assert(err >= 0); + + return (ts.tv_sec * 100) + (ts.tv_nsec / 10000000); +} + static uint64_t proc_uptime(int fd) { uint64_t val1, val2; -- cgit v1.2.3