liblttng-ust/clock.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2010 Pierre-Marc Fournier
   5  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  */
   7
   8 #ifndef _UST_CLOCK_H
   9 #define _UST_CLOCK_H
  10
  11 #include <time.h>
  12 #include <sys/time.h>
  13 #include <stdint.h>
  14 #include <stddef.h>
  15 #include <stdio.h>
  16 #include <urcu/system.h>
  17 #include <urcu/arch.h>
  18 #include <lttng/ust-clock.h>
  19
  20 #include "lttng-ust-uuid.h"
  21
  22 struct lttng_trace_clock {
  23         uint64_t (*read64)(void);
  24         uint64_t (*freq)(void);
  25         int (*uuid)(char *uuid);
  26         const char *(*name)(void);
  27         const char *(*description)(void);
  28 };
  29
  30 extern struct lttng_trace_clock *lttng_trace_clock;
  31
  32 void lttng_ust_clock_init(void);
  33
  34 /* Use the kernel MONOTONIC clock. */
  35
  36 static __inline__
  37 uint64_t trace_clock_read64_monotonic(void)
  38 {
  39         struct timespec ts;
  40
  41         if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts))) {
  42                 ts.tv_sec = 0;
  43                 ts.tv_nsec = 0;
  44         }
  45         return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
  46 }
  47
  48 static __inline__
  49 uint64_t trace_clock_read64(void)
  50 {
  51         struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
  52
  53         if (caa_likely(!ltc)) {
  54                 return trace_clock_read64_monotonic();
  55         } else {
  56                 cmm_read_barrier_depends();     /* load ltc before content */
  57                 return ltc->read64();
  58         }
  59 }
  60
  61 #endif /* _UST_CLOCK_H */