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
23 #include <common/compat/time.h>
28 #include <urcu/system.h>
29 #include <urcu/arch.h>
30 #include <lttng/ust-clock.h>
32 #include <common/compat/uuid.h>
36 struct lttng_trace_clock
{
37 uint64_t (*read64
)(void);
38 uint64_t (*freq
)(void);
39 int (*uuid
)(char *uuid
);
40 const char *(*name
)(void);
41 const char *(*description
)(void);
44 extern struct lttng_trace_clock
*lttng_trace_clock
;
46 void lttng_ust_clock_init(void);
49 * Currently using the kernel MONOTONIC clock, waiting for kernel-side
50 * LTTng to implement mmap'd trace clock.
53 /* Choosing correct trace clock */
56 uint64_t trace_clock_read64_monotonic(void)
60 if (lttng_clock_gettime(CLOCK_MONOTONIC
, &ts
)) {
61 /* TODO Report error cleanly up the chain. */
62 PERROR("clock_gettime CLOCK_MONOTONIC");
66 return ((uint64_t) ts
.tv_sec
* 1000000000ULL) + ts
.tv_nsec
;
70 uint64_t trace_clock_freq_monotonic(void)
76 int trace_clock_uuid_monotonic(char *uuid
)
83 * boot_id needs to be read once before being used concurrently
84 * to deal with a Linux kernel race. A fix is proposed for
85 * upstream, but the work-around is needed for older kernels.
87 fp
= fopen("/proc/sys/kernel/random/boot_id", "r");
91 len
= fread(uuid
, 1, LTTNG_UST_UUID_STR_LEN
- 1, fp
);
92 if (len
< LTTNG_UST_UUID_STR_LEN
- 1) {
96 uuid
[LTTNG_UST_UUID_STR_LEN
- 1] = '\0';
103 const char *trace_clock_name_monotonic(void)
109 const char *trace_clock_description_monotonic(void)
111 return "Monotonic Clock";
115 uint64_t trace_clock_read64(void)
117 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
119 if (caa_likely(!ltc
)) {
120 return trace_clock_read64_monotonic();
122 cmm_read_barrier_depends(); /* load ltc before content */
123 return ltc
->read64();
128 uint64_t trace_clock_freq(void)
130 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
133 return trace_clock_freq_monotonic();
135 cmm_read_barrier_depends(); /* load ltc before content */
141 int trace_clock_uuid(char *uuid
)
143 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
145 cmm_read_barrier_depends(); /* load ltc before content */
146 /* Use default UUID cb when NULL */
147 if (!ltc
|| !ltc
->uuid
) {
148 return trace_clock_uuid_monotonic(uuid
);
150 return ltc
->uuid(uuid
);
155 const char *trace_clock_name(void)
157 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
160 return trace_clock_name_monotonic();
162 cmm_read_barrier_depends(); /* load ltc before content */
168 const char *trace_clock_description(void)
170 struct lttng_trace_clock
*ltc
= CMM_LOAD_SHARED(lttng_trace_clock
);
173 return trace_clock_description_monotonic();
175 cmm_read_barrier_depends(); /* load ltc before content */
176 return ltc
->description();
180 #endif /* _UST_CLOCK_H */
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