X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=gettime.c;h=89a3a016e4c871a767365f96318392a65ec30ba6;hb=fa80feae51331fb170e784459fa1359d7ec3a963;hp=2037354d0116a122ffb9b698c55b7b9aacbce86b;hpb=783a3eb15f143d26eed5fd1c943f238057f3ee52;p=fio.git

diff --git a/gettime.c b/gettime.c
index 2037354d..89a3a016 100644
--- a/gettime.c
+++ b/gettime.c
@@ -15,16 +15,13 @@
 #ifdef ARCH_HAVE_CPU_CLOCK
 static unsigned long cycles_per_usec;
 static unsigned long last_cycles;
+int tsc_reliable = 0;
 #endif
 static struct timeval last_tv;
 static int last_tv_valid;
 
-static struct timeval *fio_tv;
-int fio_gtod_offload = 0;
-int fio_gtod_cpu = -1;
-static pthread_t gtod_thread;
-
-enum fio_cs fio_clock_source = CS_GTOD;
+enum fio_cs fio_clock_source = FIO_PREFERRED_CLOCK_SOURCE;
+int fio_clock_source_set = 0;
 
 #ifdef FIO_DEBUG_TIME
 
@@ -213,15 +210,17 @@ static unsigned long get_cycles_per_usec(void)
 	return c_e - c_s;
 }
 
+#define NR_TIME_ITERS	50
+
 static void calibrate_cpu_clock(void)
 {
 	double delta, mean, S;
-	unsigned long avg, cycles[10];
+	unsigned long avg, cycles[NR_TIME_ITERS];
 	int i, samples;
 
 	cycles[0] = get_cycles_per_usec();
 	S = delta = mean = 0.0;
-	for (i = 0; i < 10; i++) {
+	for (i = 0; i < NR_TIME_ITERS; i++) {
 		cycles[i] = get_cycles_per_usec();
 		delta = cycles[i] - mean;
 		if (delta) {
@@ -230,10 +229,10 @@ static void calibrate_cpu_clock(void)
 		}
 	}
 
-	S = sqrt(S / (10 - 1.0));
+	S = sqrt(S / (NR_TIME_ITERS - 1.0));
 
 	samples = avg = 0;
-	for (i = 0; i < 10; i++) {
+	for (i = 0; i < NR_TIME_ITERS; i++) {
 		double this = cycles[i];
 
 		if ((fmax(this, mean) - fmin(this, mean)) > S)
@@ -242,10 +241,10 @@ static void calibrate_cpu_clock(void)
 		avg += this;
 	}
 
-	S /= 10.0;
-	mean /= 10.0;
+	S /= (double) NR_TIME_ITERS;
+	mean /= (double) NR_TIME_ITERS;
 
-	for (i = 0; i < 10; i++)
+	for (i = 0; i < NR_TIME_ITERS; i++)
 		dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
 
 	avg /= (samples * 10);
@@ -253,7 +252,6 @@ static void calibrate_cpu_clock(void)
 	dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
 
 	cycles_per_usec = avg;
-
 }
 #else
 static void calibrate_cpu_clock(void)
@@ -265,68 +263,81 @@ void fio_clock_init(void)
 {
 	last_tv_valid = 0;
 	calibrate_cpu_clock();
+
+	/*
+	 * If the arch sets tsc_reliable != 0, then it must be good enough
+	 * to use as THE clock source. For x86 CPUs, this means the TSC
+	 * runs at a constant rate and is synced across CPU cores.
+	 */
+	if (tsc_reliable) {
+		if (!fio_clock_source_set)
+			fio_clock_source = CS_CPUCLOCK;
+	} else if (fio_clock_source == CS_CPUCLOCK)
+		log_info("fio: clocksource=cpu may not be reliable\n");
 }
 
-void fio_gtod_init(void)
+unsigned long long utime_since(struct timeval *s, struct timeval *e)
 {
-	fio_tv = smalloc(sizeof(struct timeval));
-	assert(fio_tv);
+	long sec, usec;
+	unsigned long long ret;
+
+	sec = e->tv_sec - s->tv_sec;
+	usec = e->tv_usec - s->tv_usec;
+	if (sec > 0 && usec < 0) {
+		sec--;
+		usec += 1000000;
+	}
+
+	/*
+	 * time warp bug on some kernels?
+	 */
+	if (sec < 0 || (sec == 0 && usec < 0))
+		return 0;
+
+	ret = sec * 1000000ULL + usec;
+
+	return ret;
 }
 
-void fio_gtod_update(void)
+unsigned long long utime_since_now(struct timeval *s)
 {
-	gettimeofday(fio_tv, NULL);
+	struct timeval t;
+
+	fio_gettime(&t, NULL);
+	return utime_since(s, &t);
 }
 
-static void *gtod_thread_main(void *data)
+unsigned long mtime_since(struct timeval *s, struct timeval *e)
 {
-	struct fio_mutex *mutex = data;
-
-	fio_mutex_up(mutex);
+	long sec, usec, ret;
 
-	/*
-	 * As long as we have jobs around, update the clock. It would be nice
-	 * to have some way of NOT hammering that CPU with gettimeofday(),
-	 * but I'm not sure what to use outside of a simple CPU nop to relax
-	 * it - we don't want to lose precision.
-	 */
-	while (threads) {
-		fio_gtod_update();
-		nop;
+	sec = e->tv_sec - s->tv_sec;
+	usec = e->tv_usec - s->tv_usec;
+	if (sec > 0 && usec < 0) {
+		sec--;
+		usec += 1000000;
 	}
 
-	return NULL;
+	if (sec < 0 || (sec == 0 && usec < 0))
+		return 0;
+
+	sec *= 1000UL;
+	usec /= 1000UL;
+	ret = sec + usec;
+
+	return ret;
 }
 
-int fio_start_gtod_thread(void)
+unsigned long mtime_since_now(struct timeval *s)
 {
-	struct fio_mutex *mutex;
-	pthread_attr_t attr;
-	int ret;
-
-	mutex = fio_mutex_init(0);
-	if (!mutex)
-		return 1;
-
-	pthread_attr_init(&attr);
-	pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
-	ret = pthread_create(&gtod_thread, &attr, gtod_thread_main, NULL);
-	pthread_attr_destroy(&attr);
-	if (ret) {
-		log_err("Can't create gtod thread: %s\n", strerror(ret));
-		goto err;
-	}
+	struct timeval t;
+	void *p = __builtin_return_address(0);
 
-	ret = pthread_detach(gtod_thread);
-	if (ret) {
-		log_err("Can't detatch gtod thread: %s\n", strerror(ret));
-		goto err;
-	}
+	fio_gettime(&t, p);
+	return mtime_since(s, &t);
+}
 
-	dprint(FD_MUTEX, "wait on startup_mutex\n");
-	fio_mutex_down(mutex);
-	dprint(FD_MUTEX, "done waiting on startup_mutex\n");
-err:
-	fio_mutex_remove(mutex);
-	return ret;
+unsigned long time_since_now(struct timeval *s)
+{
+	return mtime_since_now(s) / 1000;
 }