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
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
/* High precision, low overhead timing functions. powerpc64 version.
Copyright (C) 2005-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _HP_TIMING_H
#define _HP_TIMING_H 1
#include <string.h>
#include <sys/param.h>
#include <_itoa.h>
#include <atomic.h>
/* The macros defined here use the powerpc 64-bit time base register.
The time base is nominally clocked at 1/8th the CPU clock, but this
can vary.
The list of macros we need includes the following:
- HP_TIMING_AVAIL: test for availability.
- HP_TIMING_INLINE: this macro is non-zero if the functionality is not
implemented using function calls but instead uses some inlined code
which might simply consist of a few assembler instructions. We have to
know this since we might want to use the macros here in places where we
cannot make function calls.
- hp_timing_t: This is the type for variables used to store the time
values.
- HP_TIMING_ZERO: clear `hp_timing_t' object.
- HP_TIMING_NOW: place timestamp for current time in variable given as
parameter.
- HP_TIMING_DIFF_INIT: do whatever is necessary to be able to use the
HP_TIMING_DIFF macro.
- HP_TIMING_DIFF: compute difference between two times and store it
in a third. Source and destination might overlap.
- HP_TIMING_ACCUM: add time difference to another variable. This might
be a bit more complicated to implement for some platforms as the
operation should be thread-safe and 64bit arithmetic on 32bit platforms
is not.
- HP_TIMING_ACCUM_NT: this is the variant for situations where we know
there are no threads involved.
- HP_TIMING_PRINT: write decimal representation of the timing value into
the given string. This operation need not be inline even though
HP_TIMING_INLINE is specified.
*/
/* We always assume having the timestamp register. */
#define HP_TIMING_AVAIL (1)
/* We indeed have inlined functions. */
#define HP_TIMING_INLINE (1)
/* We use 64bit values for the times. */
typedef unsigned long long int hp_timing_t;
/* Set timestamp value to zero. */
#define HP_TIMING_ZERO(Var) (Var) = (0)
/* That's quite simple. Use the `mftb' instruction. Note that the value
might not be 100% accurate since there might be some more instructions
running in this moment. This could be changed by using a barrier like
'lwsync' right before the `mftb' instruction. But we are not interested
in accurate clock cycles here so we don't do this. */
#define HP_TIMING_NOW(Var) \
do { \
unsigned int hi, lo, tmp; \
__asm__ __volatile__ ("1: mfspr %0,269;" \
" mfspr %1,268;" \
" mfspr %2,269;" \
" cmpw %0,%2;" \
" bne 1b;" \
: "=&r" (hi), "=&r" (lo), "=&r" (tmp) \
: : "cr0"); \
Var = ((hp_timing_t) hi << 32) | lo; \
} while (0)
/* Use two 'mftb' instructions in a row to find out how long it takes.
On current POWER4, POWER5, and 970 processors mftb take ~10 cycles. */
#define HP_TIMING_DIFF_INIT() \
do { \
if (GLRO(dl_hp_timing_overhead) == 0) \
{ \
int __cnt = 5; \
GLRO(dl_hp_timing_overhead) = ~0ull; \
do \
{ \
hp_timing_t __t1, __t2; \
HP_TIMING_NOW (__t1); \
HP_TIMING_NOW (__t2); \
if (__t2 - __t1 < GLRO(dl_hp_timing_overhead)) \
GLRO(dl_hp_timing_overhead) = __t2 - __t1; \
} \
while (--__cnt > 0); \
} \
} while (0)
/* It's simple arithmetic in 64-bit. */
#define HP_TIMING_DIFF(Diff, Start, End) (Diff) = ((End) - (Start))
/* We need to insure that this add is atomic in threaded environments. We use
__arch_atomic_exchange_and_add_64 from atomic.h to get thread safety. */
#define HP_TIMING_ACCUM(Sum, Diff) \
do { \
hp_timing_t __diff = (Diff) - GLRO(dl_hp_timing_overhead); \
__arch_atomic_exchange_and_add_64 (&(Sum), __diff); \
} while (0)
/* No threads, no extra work. */
#define HP_TIMING_ACCUM_NT(Sum, Diff) (Sum) += (Diff)
/* Print the time value. */
#define HP_TIMING_PRINT(Buf, Len, Val) \
do { \
char __buf[20]; \
char *__cp = _itoa (Val, __buf + sizeof (__buf), 10, 0); \
size_t __len = (Len); \
char *__dest = (Buf); \
while (__len-- > 0 && __cp < __buf + sizeof (__buf)) \
*__dest++ = *__cp++; \
memcpy (__dest, " ticks", MIN (__len, sizeof (" ticks"))); \
} while (0)
#endif /* hp-timing.h */
|
