1 /* Copyright (C) 2010 Pierre-Marc Fournier
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <ust/kcompat/kcompat.h>
27 /* There are two types of clocks that can be used.
29 - gettimeofday() clock
31 Microbenchmarks on Linux 2.6.30 on Core2 Duo 3GHz (functions are inlined):
32 Calls (100000000) to tsc(): 4004035641 cycles or 40 cycles/call
33 Calls (100000000) to gettimeofday(): 9723158352 cycles or 97 cycles/call
35 For merging traces with the kernel, a time source compatible with that of
36 the kernel is necessary.
38 Instead of gettimeofday(), we are now using clock_gettime for better
39 precision and monotonicity.
42 /* Only available for x86 arch */
43 #define CLOCK_TRACE_FREQ 14
44 #define CLOCK_TRACE 15
45 union lttng_timespec
{
50 extern int ust_clock_source
;
52 /* Choosing correct trace clock */
54 static __inline__ u64
trace_clock_read64(void)
58 union lttng_timespec
*lts
= (union lttng_timespec
*) &ts
;
60 clock_gettime(ust_clock_source
, &ts
);
62 * Clock source can change when loading the binary (tracectl.c)
63 * so we must check if the clock source has changed before
64 * returning the correct value
66 if (likely(ust_clock_source
== CLOCK_TRACE
)) {
67 retval
= lts
->lttng_ts
;
68 } else { /* CLOCK_MONOTONIC */
78 static __inline__ u64
trace_clock_frequency(void)
81 union lttng_timespec
*lts
= (union lttng_timespec
*) &ts
;
83 #if __i386__ || __x86_64__
84 if (likely(ust_clock_source
== CLOCK_TRACE
)) {
85 clock_gettime(CLOCK_TRACE_FREQ
, &ts
);
92 static __inline__ u32
trace_clock_freq_scale(void)
97 #endif /* _UST_CLOCK_H */
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