1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
|
// Copyright (c) 2004, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ----------------------------------------------------------------------
// CycleClock
// A CycleClock tells you the current time in Cycles. The "time"
// is actually time since power-on. This is like time() but doesn't
// involve a system call and is much more precise.
//
// NOTE: Not all cpu/platform/kernel combinations guarantee that this
// clock increments at a constant rate or is synchronized across all logical
// cpus in a system.
//
// Also, in some out of order CPU implementations, the CycleClock is not
// serializing. So if you're trying to count at cycles granularity, your
// data might be inaccurate due to out of order instruction execution.
// ----------------------------------------------------------------------
#ifndef GOOGLE_BASE_CYCLECLOCK_H_
#define GOOGLE_BASE_CYCLECLOCK_H_
#include "base/basictypes.h" // make sure we get the def for int64
#if defined(__MACH__) && defined(__APPLE__)
#include <mach/mach_time.h>
#endif
// NOTE: only i386 and x86_64 have been well tested.
// PPC, sparc, alpha, and ia64 are based on
// http://peter.kuscsik.com/wordpress/?p=14
// with modifications by m3b. cf
// https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
struct CycleClock {
// This should return the number of cycles since power-on. Thread-safe.
static inline int64 Now() {
#if defined(__MACH__) && defined(__APPLE__)
// this goes at the top because we need ALL Macs, regardless
// of architecture, to return the number of "mach time units"
// that have passes since startup. See sysinfo.cc where
// InitializeSystemInfo() sets the supposed cpu clock frequency of macs
// to the number of mach time units per second, not actual
// CPU clock frequency (which can change in the face of CPU
// frequency scaling). also note that when the Mac sleeps,
// this counter pauses; it does not continue counting, nor resets
// to zero.
return mach_absolute_time();
#elif defined(__i386__)
int64 ret;
__asm__ volatile ("rdtsc"
: "=A" (ret) );
return ret;
#elif defined(__x86_64__) || defined(__amd64__)
uint64 low, high;
__asm__ volatile ("rdtsc" : "=a" (low), "=d" (high));
return (high << 32) | low;
#elif defined(__powerpc__) || defined(__ppc__)
// This returns a time-base, which is not always precisely a cycle-count.
int64 tbl, tbu0, tbu1;
asm("mftbu %0" : "=r" (tbu0));
asm("mftb %0" : "=r" (tbl ));
asm("mftbu %0" : "=r" (tbu1));
tbl &= -static_cast<int64>(tbu0 == tbu1);
// high 32 bits in tbu1; low 32 bits in tbl (tbu0 is garbage)
return (tbu1 << 32) | tbl;
#elif defined(__sparc__)
int64 tick;
asm(".byte 0x83, 0x41, 0x00, 0x00");
asm("mov %%g1, %0" : "=r" (tick));
return tick;
#elif defined(__ia64__)
int64 itc;
asm("mov %0 = ar.itc" : "=r" (itc));
return itc;
#elif defined(_MSC_VER) && defined(_M_IX86)
_asm rdtsc
#else
// We could define __alpha here as well, but it only has a 32-bit
// timer (good for like 4 seconds), which isn't very useful.
#error You need to define CycleTimer for your O/S and CPU
#endif
}
};
#endif // GOOGLE_BASE_CYCLECLOCK_H_
|
