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 <axboe@fb.com>
diff --git a/gettime.c b/gettime.c
index 172b478..5ceb809 100644
--- a/gettime.c
+++ b/gettime.c
@@ -361,7 +361,7 @@
* 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 @@
#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_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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
#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