From aad918e47d119eb2043311f1a2a45ce109c047d1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 23 Dec 2014 10:41:34 -0700 Subject: [PATCH] gettime: add basic init cpuclock test Some systems claim to have a synced and constant rate tsc, even if they don't. So add the basic cpuclock-test test as part of fio trusting the CPU clock, to avoid using the CPU clock on a system where the TSC truly isn't synced between CPUs. Signed-off-by: Jens Axboe --- gettime.c | 70 ++++++++++++++++++++++++++++++++++++++----------------- gettime.h | 2 +- init.c | 2 +- 3 files changed, 50 insertions(+), 24 deletions(-) diff --git a/gettime.c b/gettime.c index 172b4782..5ceb809d 100644 --- a/gettime.c +++ b/gettime.c @@ -361,7 +361,7 @@ void fio_clock_init(void) * runs at a constant rate and is synced across CPU cores. */ if (tsc_reliable) { - if (!fio_clock_source_set) + if (!fio_clock_source_set && !fio_monotonic_clocktest(0)) fio_clock_source = CS_CPUCLOCK; } else if (fio_clock_source == CS_CPUCLOCK) log_info("fio: clocksource=cpu may not be reliable\n"); @@ -436,7 +436,8 @@ uint64_t time_since_now(const struct timeval *s) #if defined(FIO_HAVE_CPU_AFFINITY) && defined(ARCH_HAVE_CPU_CLOCK) && \ defined(CONFIG_SFAA) -#define CLOCK_ENTRIES 100000 +#define CLOCK_ENTRIES_DEBUG 100000 +#define CLOCK_ENTRIES_TEST 10000 struct clock_entry { uint32_t seq; @@ -447,8 +448,10 @@ struct clock_entry { struct clock_thread { pthread_t thread; int cpu; + int debug; pthread_mutex_t lock; pthread_mutex_t started; + unsigned long nr_entries; uint32_t *seq; struct clock_entry *entries; }; @@ -479,7 +482,7 @@ static void *clock_thread_fn(void *data) last_seq = 0; c = &t->entries[0]; - for (i = 0; i < CLOCK_ENTRIES; i++, c++) { + for (i = 0; i < t->nr_entries; i++, c++) { uint32_t seq; uint64_t tsc; @@ -495,8 +498,12 @@ static void *clock_thread_fn(void *data) c->tsc = tsc; } - log_info("cs: cpu%3d: %llu clocks seen\n", t->cpu, - (unsigned long long) t->entries[i - 1].tsc - t->entries[0].tsc); + if (t->debug) { + unsigned long long clocks; + + clocks = t->entries[i - 1].tsc - t->entries[0].tsc; + log_info("cs: cpu%3d: %llu clocks seen\n", t->cpu, clocks); + } /* * The most common platform clock breakage is returning zero @@ -519,38 +526,49 @@ static int clock_cmp(const void *p1, const void *p2) return c1->seq - c2->seq; } -int fio_monotonic_clocktest(void) +int fio_monotonic_clocktest(int debug) { struct clock_thread *cthreads; unsigned int nr_cpus = cpus_online(); struct clock_entry *entries; - unsigned long tentries, failed = 0; + unsigned long nr_entries, tentries, failed = 0; struct clock_entry *prev, *this; uint32_t seq = 0; unsigned int i; - log_info("cs: reliable_tsc: %s\n", tsc_reliable ? "yes" : "no"); + if (debug) { + log_info("cs: reliable_tsc: %s\n", tsc_reliable ? "yes" : "no"); #ifdef FIO_INC_DEBUG - fio_debug |= 1U << FD_TIME; + fio_debug |= 1U << FD_TIME; #endif + nr_entries = CLOCK_ENTRIES_DEBUG; + } else + nr_entries = CLOCK_ENTRIES_TEST; + calibrate_cpu_clock(); + + if (debug) { #ifdef FIO_INC_DEBUG - fio_debug &= ~(1U << FD_TIME); + fio_debug &= ~(1U << FD_TIME); #endif + } cthreads = malloc(nr_cpus * sizeof(struct clock_thread)); - tentries = CLOCK_ENTRIES * nr_cpus; + tentries = nr_entries * nr_cpus; entries = malloc(tentries * sizeof(struct clock_entry)); - log_info("cs: Testing %u CPUs\n", nr_cpus); + if (debug) + log_info("cs: Testing %u CPUs\n", nr_cpus); for (i = 0; i < nr_cpus; i++) { struct clock_thread *t = &cthreads[i]; t->cpu = i; + t->debug = debug; t->seq = &seq; - t->entries = &entries[i * CLOCK_ENTRIES]; + t->nr_entries = nr_entries; + t->entries = &entries[i * nr_entries]; pthread_mutex_init(&t->lock, NULL); pthread_mutex_init(&t->started, NULL); pthread_mutex_lock(&t->lock); @@ -584,7 +602,8 @@ int fio_monotonic_clocktest(void) free(cthreads); if (failed) { - log_err("Clocksource test: %lu threads failed\n", failed); + if (debug) + log_err("Clocksource test: %lu threads failed\n", failed); goto err; } @@ -601,6 +620,11 @@ int fio_monotonic_clocktest(void) if (prev->tsc > this->tsc) { uint64_t diff = prev->tsc - this->tsc; + if (!debug) { + failed++; + break; + } + log_info("cs: CPU clock mismatch (diff=%llu):\n", (unsigned long long) diff); log_info("\t CPU%3u: TSC=%llu, SEQ=%u\n", prev->cpu, (unsigned long long) prev->tsc, prev->seq); @@ -611,11 +635,12 @@ int fio_monotonic_clocktest(void) prev = this; } - if (failed) - log_info("cs: Failed: %lu\n", failed); - else - log_info("cs: Pass!\n"); - + if (debug) { + if (failed) + log_info("cs: Failed: %lu\n", failed); + else + log_info("cs: Pass!\n"); + } err: free(entries); return !!failed; @@ -623,10 +648,11 @@ err: #else /* defined(FIO_HAVE_CPU_AFFINITY) && defined(ARCH_HAVE_CPU_CLOCK) */ -int fio_monotonic_clocktest(void) +int fio_monotonic_clocktest(int debug) { - log_info("cs: current platform does not support CPU clocks\n"); - return 0; + if (debug) + log_info("cs: current platform does not support CPU clocks\n"); + return 1; } #endif diff --git a/gettime.h b/gettime.h index b775ef3a..eb3537b1 100644 --- a/gettime.h +++ b/gettime.h @@ -17,7 +17,7 @@ extern void fio_gettime(struct timeval *, void *); extern void fio_gtod_init(void); extern void fio_clock_init(void); extern int fio_start_gtod_thread(void); -extern int fio_monotonic_clocktest(void); +extern int fio_monotonic_clocktest(int debug); extern void fio_local_clock_init(int); extern struct timeval *fio_tv; diff --git a/init.c b/init.c index d3dec0a1..dc563fd2 100644 --- a/init.c +++ b/init.c @@ -2238,7 +2238,7 @@ int parse_cmd_line(int argc, char *argv[], int client_type) case 'T': did_arg = 1; do_exit++; - exit_val = fio_monotonic_clocktest(); + exit_val = fio_monotonic_clocktest(1); break; case 'G': did_arg = 1; -- 2.25.1