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-rw-r--r--gettime.c106
1 files changed, 100 insertions, 6 deletions
diff --git a/gettime.c b/gettime.c
index 8ec70b9f..08d2d2b3 100644
--- a/gettime.c
+++ b/gettime.c
@@ -3,6 +3,7 @@
*/
#include <unistd.h>
+#include <math.h>
#include <sys/time.h>
#include "fio.h"
@@ -10,14 +11,17 @@
#include "hash.h"
-static int clock_gettime_works = 0;
+static unsigned long cycles_per_usec;
static struct timeval last_tv;
+static unsigned long last_cycles;
static int last_tv_valid;
static struct timeval *fio_tv;
int fio_gtod_offload = 0;
int fio_gtod_cpu = -1;
+enum fio_cs fio_clock_source = CS_GTOD;
+
#ifdef FIO_DEBUG_TIME
#define HASH_BITS 8
@@ -124,19 +128,44 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
if (fio_tv) {
memcpy(tp, fio_tv, sizeof(*tp));
return;
- } else if (!clock_gettime_works) {
-gtod:
+ }
+
+ switch (fio_clock_source) {
+ case CS_GTOD:
gettimeofday(tp, NULL);
- } else {
+ break;
+ case CS_CGETTIME: {
struct timespec ts;
if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
- clock_gettime_works = 0;
- goto gtod;
+ log_err("fio: clock_gettime fails\n");
+ assert(0);
}
tp->tv_sec = ts.tv_sec;
tp->tv_usec = ts.tv_nsec / 1000;
+ break;
+ }
+#ifdef ARCH_HAVE_CPU_CLOCK
+ case CS_CPUCLOCK: {
+ unsigned long long usecs, t;
+
+ t = get_cpu_clock();
+ if (t < last_cycles) {
+ dprint(FD_TIME, "CPU clock going back in time\n");
+ t = last_cycles;
+ }
+
+ usecs = t / cycles_per_usec;
+ tp->tv_sec = usecs / 1000000;
+ tp->tv_usec = usecs % 1000000;
+ last_cycles = t;
+ break;
+ }
+#endif
+ default:
+ log_err("fio: invalid clock source %d\n", fio_clock_source);
+ break;
}
/*
@@ -154,6 +183,71 @@ gtod:
memcpy(&last_tv, tp, sizeof(*tp));
}
+static unsigned long get_cycles_per_usec(void)
+{
+ struct timeval s, e;
+ unsigned long long c_s, c_e;
+
+ gettimeofday(&s, NULL);
+ c_s = get_cpu_clock();
+ do {
+ unsigned long long elapsed;
+
+ gettimeofday(&e, NULL);
+ elapsed = utime_since(&s, &e);
+ if (elapsed >= 10) {
+ c_e = get_cpu_clock();
+ break;
+ }
+ } while (1);
+
+ return c_e - c_s;
+}
+
+void fio_clock_init(void)
+{
+ double delta, mean, S;
+ unsigned long avg, cycles[10];
+ int i, samples;
+
+ last_tv_valid = 0;
+
+ cycles[0] = get_cycles_per_usec();
+ S = delta = mean = 0.0;
+ for (i = 0; i < 10; i++) {
+ cycles[i] = get_cycles_per_usec();
+ delta = cycles[i] - mean;
+ if (delta) {
+ mean += delta / (i + 1.0);
+ S += delta * (cycles[i] - mean);
+ }
+ }
+
+ S = sqrt(S / (10 - 1.0));
+
+ samples = avg = 0;
+ for (i = 0; i < 10; i++) {
+ double this = cycles[i];
+
+ if ((max(this, mean) - min(this, mean)) > S)
+ continue;
+ samples++;
+ avg += this;
+ }
+
+ S /= 10.0;
+ mean /= 10.0;
+
+ for (i = 0; i < 10; i++)
+ dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
+
+ avg /= (samples * 10);
+ dprint(FD_TIME, "avg: %lu\n", avg);
+ dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
+
+ cycles_per_usec = avg;
+}
+
void fio_gtod_init(void)
{
fio_tv = smalloc(sizeof(struct timeval));