liblttng-ust/clock.h

   1 /*
   2  * Copyright (C) 2010  Pierre-Marc Fournier
   3  * Copyright (C) 2011  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; version 2.1 of
   8  * the License.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  18  */
  19
  20 #ifndef _UST_CLOCK_H
  21 #define _UST_CLOCK_H
  22
  23 #include <time.h>
  24 #include <sys/time.h>
  25 #include <stdint.h>
  26 #include <stddef.h>
  27 #include <stdio.h>
  28 #include <urcu/system.h>
  29 #include <urcu/arch.h>
  30 #include <lttng/ust-clock.h>
  31
  32 #include "lttng-ust-uuid.h"
  33
  34 struct lttng_trace_clock {
  35         uint64_t (*read64)(void);
  36         uint64_t (*freq)(void);
  37         int (*uuid)(char *uuid);
  38         const char *(*name)(void);
  39         const char *(*description)(void);
  40 };
  41
  42 extern struct lttng_trace_clock *lttng_trace_clock;
  43
  44 void lttng_ust_clock_init(void);
  45
  46 /* Use the kernel MONOTONIC clock. */
  47
  48 static __inline__
  49 uint64_t trace_clock_read64_monotonic(void)
  50 {
  51         struct timespec ts;
  52
  53         if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts))) {
  54                 ts.tv_sec = 0;
  55                 ts.tv_nsec = 0;
  56         }
  57         return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
  58 }
  59
  60 static __inline__
  61 uint64_t trace_clock_read64(void)
  62 {
  63         struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
  64
  65         if (caa_likely(!ltc)) {
  66                 return trace_clock_read64_monotonic();
  67         } else {
  68                 cmm_read_barrier_depends();     /* load ltc before content */
  69                 return ltc->read64();
  70         }
  71 }
  72
  73 #endif /* _UST_CLOCK_H */