2 * Copyright (C) 2010 Pierre-Marc Fournier
3 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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
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.
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
28 #include <urcu/system.h>
29 #include <urcu/arch.h>
30 #include <lttng/ust-clock.h>
32 #include "lttng-ust-uuid.h"
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);
42 extern struct lttng_trace_clock
*lttng_trace_clock
;
44 void lttng_ust_clock_init(void);
46 /* Use the kernel MONOTONIC clock. */
49 uint64_t trace_clock_read64_monotonic(void)
53 clock_gettime(CLOCK_MONOTONIC
, &ts
);
54 return ((uint64_t) ts
.tv_sec
* 1000000000ULL) + ts
.tv_nsec
;
58 uint64_t trace_clock_freq_monotonic(void)
64 int trace_clock_uuid_monotonic(char *uuid
)
71 * boot_id needs to be read once before being used concurrently
72 * to deal with a Linux kernel race. A fix is proposed for
73 * upstream, but the work-around is needed for older kernels.
75 fp
= fopen("/proc/sys/kernel/random/boot_id", "r");
79 len
= fread(uuid
, 1, LTTNG_UST_UUID_STR_LEN
- 1, fp
);
80 if (len
< LTTNG_UST_UUID_STR_LEN
- 1) {
84 uuid
[LTTNG_UST_UUID_STR_LEN
- 1] = '\0';
91 const char *trace_clock_name_monotonic(void)
97 const char *trace_clock_description_monotonic(void)
99 return "Monotonic Clock";
103 uint64_t trace_clock_read64(void)
105 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
107 if (caa_likely(!ltc
)) {
108 return trace_clock_read64_monotonic();
110 cmm_read_barrier_depends(); /* load ltc before content */
111 return ltc
->read64();
116 uint64_t trace_clock_freq(void)
118 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
121 return trace_clock_freq_monotonic();
123 cmm_read_barrier_depends(); /* load ltc before content */
129 int trace_clock_uuid(char *uuid
)
131 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
133 cmm_read_barrier_depends(); /* load ltc before content */
134 /* Use default UUID cb when NULL */
135 if (!ltc
|| !ltc
->uuid
) {
136 return trace_clock_uuid_monotonic(uuid
);
138 return ltc
->uuid(uuid
);
143 const char *trace_clock_name(void)
145 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
148 return trace_clock_name_monotonic();
150 cmm_read_barrier_depends(); /* load ltc before content */
156 const char *trace_clock_description(void)
158 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
161 return trace_clock_description_monotonic();
163 cmm_read_barrier_depends(); /* load ltc before content */
164 return ltc
->description();
168 #endif /* _UST_CLOCK_H */
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