Use clock_gettime() for CPU clock calibration

gettimeofday() has very poor resolution on some platforms. So
use clock_gettime() instead.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/gettime.c b/gettime.c
index 248f14691a5b307c8ae17e4fc6b0111ae6e2c2ec..035d275df60e2fc325be540818a130fc7835aba3 100644 (file)
--- a/gettime.c
+++ b/gettime.c
@@ -120,6 +120,15 @@ static void fio_init gtod_init(void)
 
 #endif /* FIO_DEBUG_TIME */
 
+static int fill_clock_gettime(struct timespec *ts)
+{
+#ifdef FIO_HAVE_CLOCK_MONOTONIC
+       return clock_gettime(CLOCK_MONOTONIC, ts);
+#else
+       return clock_gettime(CLOCK_REALTIME, ts);
+#endif
+}
+
 #ifdef FIO_DEBUG_TIME
 void fio_gettime(struct timeval *tp, void *caller)
 #else
@@ -148,11 +157,7 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
        case CS_CGETTIME: {
                struct timespec ts;
 
-#ifdef FIO_HAVE_CLOCK_MONOTONIC
-               if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
-#else
-               if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
-#endif
+               if (fill_clock_gettime(&ts) < 0) {
                        log_err("fio: clock_gettime fails\n");
                        assert(0);
                }
@@ -203,15 +208,22 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
 #ifdef ARCH_HAVE_CPU_CLOCK
 static unsigned long get_cycles_per_usec(void)
 {
+       struct timespec ts;
        struct timeval s, e;
        unsigned long long c_s, c_e;
 
-       gettimeofday(&s, NULL);
+       fill_clock_gettime(&ts);
+       s.tv_sec = ts.tv_sec;
+       s.tv_usec = ts.tv_nsec / 1000;
+
        c_s = get_cpu_clock();
        do {
                unsigned long long elapsed;
 
-               gettimeofday(&e, NULL);
+               fill_clock_gettime(&ts);
+               e.tv_sec = ts.tv_sec;
+               e.tv_usec = ts.tv_nsec / 1000;
+
                elapsed = utime_since(&s, &e);
                if (elapsed >= 1280) {
                        c_e = get_cpu_clock();