Add gettime.h

[fio.git] / gettime.c

diff --git a/gettime.c b/gettime.c
index 80eeaf14bcbb75293a1621382eaa8d765fe2d015..cf0d664030d2b2d82267b79e15ee53d04205bb0d 100644 (file)
--- a/gettime.c
+++ b/gettime.c
@@ -3,16 +3,29 @@
  */
 
 #include <unistd.h>
+#include <math.h>
 #include <sys/time.h>
+#include <time.h>
 
 #include "fio.h"
+#include "smalloc.h"
 
 #include "hash.h"
 
-static int clock_gettime_works;
+#ifdef ARCH_HAVE_CPU_CLOCK
+static unsigned long cycles_per_usec;
+static unsigned long last_cycles;
+#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;
+
 #ifdef FIO_DEBUG_TIME
 
 #define HASH_BITS      8
@@ -116,19 +129,51 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
 
        gtod_log_caller(caller);
 #endif
-       if (!clock_gettime_works) {
-gtod:
+       if (fio_tv) {
+               memcpy(tp, fio_tv, sizeof(*tp));
+               return;
+       }
+
+       switch (fio_clock_source) {
+       case CS_GTOD:
                gettimeofday(tp, NULL);
-       } else {
+               break;
+       case CS_CGETTIME: {
                struct timespec ts;
 
+#ifdef FIO_HAVE_CLOCK_MONOTONIC
                if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
-                       clock_gettime_works = 0;
-                       goto gtod;
+#else
+               if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
+#endif
+                       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;
        }
 
        /*
@@ -145,3 +190,143 @@ gtod:
        last_tv_valid = 1;
        memcpy(&last_tv, tp, sizeof(*tp));
 }
+
+#ifdef ARCH_HAVE_CPU_CLOCK
+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;
+}
+
+static void calibrate_cpu_clock(void)
+{
+       double delta, mean, S;
+       unsigned long avg, cycles[10];
+       int i, samples;
+
+       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 ((fmax(this, mean) - fmin(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;
+
+}
+#else
+static void calibrate_cpu_clock(void)
+{
+}
+#endif
+
+void fio_clock_init(void)
+{
+       last_tv_valid = 0;
+       calibrate_cpu_clock();
+}
+
+void fio_gtod_init(void)
+{
+       fio_tv = smalloc(sizeof(struct timeval));
+       assert(fio_tv);
+}
+
+static void fio_gtod_update(void)
+{
+       gettimeofday(fio_tv, NULL);
+}
+
+static void *gtod_thread_main(void *data)
+{
+       struct fio_mutex *mutex = data;
+
+       fio_mutex_up(mutex);
+
+       /*
+        * 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;
+       }
+
+       return NULL;
+}
+
+int fio_start_gtod_thread(void)
+{
+       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;
+       }
+
+       ret = pthread_detach(gtod_thread);
+       if (ret) {
+               log_err("Can't detatch gtod thread: %s\n", strerror(ret));
+               goto err;
+       }
+
+       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;
+}