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
|
/* elision-lock.c: Elided pthread mutex lock.
Copyright (C) 2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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/>. */
#include <stdio.h>
#include <pthread.h>
#include <pthreadP.h>
#include <lowlevellock.h>
#include <elision-conf.h>
#include "htm.h"
/* PowerISA 2.0.7 Section B.5.5 defines isync to be insufficient as a
barrier in acquire mechanism for HTM operations, a strong 'sync' is
required. */
#undef __arch_compare_and_exchange_val_32_acq
#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
({ \
__typeof (*(mem)) __tmp; \
__typeof (mem) __memp = (mem); \
__asm __volatile ( \
"1: lwarx %0,0,%1" MUTEX_HINT_ACQ "\n" \
" cmpw %0,%2\n" \
" bne 2f\n" \
" stwcx. %3,0,%1\n" \
" bne- 1b\n" \
"2: sync" \
: "=&r" (__tmp) \
: "b" (__memp), "r" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp; \
})
#if !defined(LLL_LOCK) && !defined(EXTRAARG)
/* Make sure the configuration code is always linked in for static
libraries. */
#include "elision-conf.c"
#endif
#ifndef EXTRAARG
# define EXTRAARG
#endif
#ifndef LLL_LOCK
# define LLL_LOCK(a,b) lll_lock(a,b), 0
#endif
#define aconf __elision_aconf
/* Adaptive lock using transactions.
By default the lock region is run as a transaction, and when it
aborts or the lock is busy the lock adapts itself. */
int
__lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
{
if (*adapt_count > 0)
{
(*adapt_count)--;
goto use_lock;
}
int try_begin = aconf.try_tbegin;
while (1)
{
if (__builtin_tbegin (0))
{
if (*lock == 0)
return 0;
/* Lock was busy. Fall back to normal locking. */
__builtin_tabort (_ABORT_LOCK_BUSY);
}
else
{
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
for the next couple of calls. */
if (try_begin-- <= 0
|| _TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
{
if (aconf.skip_lock_internal_abort > 0)
*adapt_count = aconf.skip_lock_internal_abort;
goto use_lock;
}
/* Same logic as above, but for for a number of temporary failures
in a row. */
else if (aconf.skip_lock_out_of_tbegin_retries > 0
&& aconf.try_tbegin > 0)
*adapt_count = aconf.skip_lock_out_of_tbegin_retries;
}
}
use_lock:
return LLL_LOCK ((*lock), pshared);
}
|
