X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=gettime.c;h=a95b5452e5d5b3dcb382fb40ad7f79715ebfdc73;hp=9f8362090095c2d679c2b568274649d931aa8942;hb=73df3e072e210c93934d21668cc8adba4ae74d77;hpb=b220c6d6f37fc55760d66728f6f9f521ea2f9b46

diff --git a/gettime.c b/gettime.c
index 9f836209..a95b5452 100644
--- a/gettime.c
+++ b/gettime.c
@@ -16,13 +16,15 @@
 #if defined(ARCH_HAVE_CPU_CLOCK) && !defined(ARCH_CPU_CLOCK_CYCLES_PER_USEC)
 static unsigned long cycles_per_usec;
 static unsigned long inv_cycles_per_usec;
+static uint64_t max_cycles_for_mult;
+static unsigned long long cycles_start, cycles_wrap;
 #endif
 int tsc_reliable = 0;
 
 struct tv_valid {
-	struct timeval last_tv;
 	uint64_t last_cycles;
 	int last_tv_valid;
+	int warned;
 };
 #ifdef CONFIG_TLS_THREAD
 static __thread struct tv_valid static_tv_valid;
@@ -64,7 +66,7 @@ static struct gtod_log *find_hash(void *caller)
 	return NULL;
 }
 
-static struct gtod_log *find_log(void *caller)
+static void inc_caller(void *caller)
 {
 	struct gtod_log *log = find_hash(caller);
 
@@ -80,16 +82,13 @@ static struct gtod_log *find_log(void *caller)
 		flist_add_tail(&log->list, &hash[h]);
 	}
 
-	return log;
+	log->calls++;
 }
 
 static void gtod_log_caller(void *caller)
 {
-	if (gtod_inited) {
-		struct gtod_log *log = find_log(caller);
-
-		log->calls++;
-	}
+	if (gtod_inited)
+		inc_caller(caller);
 }
 
 static void fio_exit fio_dump_gtod(void)
@@ -136,7 +135,7 @@ static int fill_clock_gettime(struct timespec *ts)
 }
 #endif
 
-static void *__fio_gettime(struct timeval *tp)
+static void __fio_gettime(struct timeval *tp)
 {
 	struct tv_valid *tv;
 
@@ -171,16 +170,25 @@ static void *__fio_gettime(struct timeval *tp)
 		uint64_t usecs, t;
 
 		t = get_cpu_clock();
-		if (tv && t < tv->last_cycles) {
-			dprint(FD_TIME, "CPU clock going back in time\n");
-			t = tv->last_cycles;
-		} else if (tv)
-			tv->last_cycles = t;
+		if (t < cycles_start && !cycles_wrap)
+			cycles_wrap = 1;
+		else if (cycles_wrap && t >= cycles_start) {
+			if (!tv->warned) {
+				log_err("fio: double CPU clock wrap\n");
+				tv->warned = 1;
+			}
+		}
 
+		t -= cycles_start;
+		tv->last_cycles = t;
+		tv->last_tv_valid = 1;
 #ifdef ARCH_CPU_CLOCK_CYCLES_PER_USEC
 		usecs = t / ARCH_CPU_CLOCK_CYCLES_PER_USEC;
 #else
-		usecs = (t * inv_cycles_per_usec) / 16777216UL;
+		if (t < max_cycles_for_mult)
+			usecs = (t * inv_cycles_per_usec) / 16777216UL;
+		else
+			usecs = t / cycles_per_usec;
 #endif
 		tp->tv_sec = usecs / 1000000;
 		tp->tv_usec = usecs % 1000000;
@@ -191,8 +199,6 @@ static void *__fio_gettime(struct timeval *tp)
 		log_err("fio: invalid clock source %d\n", fio_clock_source);
 		break;
 	}
-
-	return tv;
 }
 
 #ifdef FIO_DEBUG_TIME
@@ -201,36 +207,16 @@ void fio_gettime(struct timeval *tp, void *caller)
 void fio_gettime(struct timeval *tp, void fio_unused *caller)
 #endif
 {
-	struct tv_valid *tv;
-
 #ifdef FIO_DEBUG_TIME
 	if (!caller)
 		caller = __builtin_return_address(0);
 
 	gtod_log_caller(caller);
 #endif
-	if (fio_unlikely(fio_tv)) {
-		memcpy(tp, fio_tv, sizeof(*tp));
+	if (fio_unlikely(fio_gettime_offload(tp)))
 		return;
-	}
 
-	tv = __fio_gettime(tp);
-
-	/*
-	 * If Linux is using the tsc clock on non-synced processors,
-	 * sometimes time can appear to drift backwards. Fix that up.
-	 */
-	if (tv) {
-		if (tv->last_tv_valid) {
-			if (tp->tv_sec < tv->last_tv.tv_sec)
-				tp->tv_sec = tv->last_tv.tv_sec;
-			else if (tv->last_tv.tv_sec == tp->tv_sec &&
-				 tp->tv_usec < tv->last_tv.tv_usec)
-				tp->tv_usec = tv->last_tv.tv_usec;
-		}
-		tv->last_tv_valid = 1;
-		memcpy(&tv->last_tv, tp, sizeof(*tp));
-	}
+	__fio_gettime(tp);
 }
 
 #if defined(ARCH_HAVE_CPU_CLOCK) && !defined(ARCH_CPU_CLOCK_CYCLES_PER_USEC)
@@ -316,7 +302,10 @@ static int calibrate_cpu_clock(void)
 
 	cycles_per_usec = avg;
 	inv_cycles_per_usec = 16777216UL / cycles_per_usec;
+	max_cycles_for_mult = ~0ULL / inv_cycles_per_usec;
 	dprint(FD_TIME, "inv_cycles_per_usec=%lu\n", inv_cycles_per_usec);
+	cycles_start = get_cpu_clock();
+	dprint(FD_TIME, "cycles_start=%llu\n", cycles_start);
 	return 0;
 }
 #else
@@ -336,8 +325,10 @@ void fio_local_clock_init(int is_thread)
 	struct tv_valid *t;
 
 	t = calloc(1, sizeof(*t));
-	if (pthread_setspecific(tv_tls_key, t))
+	if (pthread_setspecific(tv_tls_key, t)) {
 		log_err("fio: can't set TLS key\n");
+		assert(0);
+	}
 }
 
 static void kill_tv_tls_key(void *data)
@@ -531,7 +522,7 @@ static int clock_cmp(const void *p1, const void *p2)
 
 int fio_monotonic_clocktest(void)
 {
-	struct clock_thread *threads;
+	struct clock_thread *cthreads;
 	unsigned int nr_cpus = cpus_online();
 	struct clock_entry *entries;
 	unsigned long tentries, failed = 0;
@@ -549,14 +540,14 @@ int fio_monotonic_clocktest(void)
 	fio_debug &= ~(1U << FD_TIME);
 #endif
 
-	threads = malloc(nr_cpus * sizeof(struct clock_thread));
+	cthreads = malloc(nr_cpus * sizeof(struct clock_thread));
 	tentries = CLOCK_ENTRIES * nr_cpus;
 	entries = malloc(tentries * sizeof(struct clock_entry));
 
 	log_info("cs: Testing %u CPUs\n", nr_cpus);
 
 	for (i = 0; i < nr_cpus; i++) {
-		struct clock_thread *t = &threads[i];
+		struct clock_thread *t = &cthreads[i];
 
 		t->cpu = i;
 		t->seq = &seq;
@@ -572,26 +563,26 @@ int fio_monotonic_clocktest(void)
 	}
 
 	for (i = 0; i < nr_cpus; i++) {
-		struct clock_thread *t = &threads[i];
+		struct clock_thread *t = &cthreads[i];
 
 		pthread_mutex_lock(&t->started);
 	}
 
 	for (i = 0; i < nr_cpus; i++) {
-		struct clock_thread *t = &threads[i];
+		struct clock_thread *t = &cthreads[i];
 
 		pthread_mutex_unlock(&t->lock);
 	}
 
 	for (i = 0; i < nr_cpus; i++) {
-		struct clock_thread *t = &threads[i];
+		struct clock_thread *t = &cthreads[i];
 		void *ret;
 
 		pthread_join(t->thread, &ret);
 		if (ret)
 			failed++;
 	}
-	free(threads);
+	free(cthreads);
 
 	if (failed) {
 		log_err("Clocksource test: %lu threads failed\n", failed);