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1 /* Copyright (c) 2009, Google Inc. | 1 /* Copyright (c) 2009, Google Inc. |
2 * All rights reserved. | 2 * All rights reserved. |
3 * | 3 * |
4 * Redistribution and use in source and binary forms, with or without | 4 * Redistribution and use in source and binary forms, with or without |
5 * modification, are permitted provided that the following conditions are | 5 * modification, are permitted provided that the following conditions are |
6 * met: | 6 * met: |
7 * | 7 * |
8 * * Redistributions of source code must retain the above copyright | 8 * * Redistributions of source code must retain the above copyright |
9 * notice, this list of conditions and the following disclaimer. | 9 * notice, this list of conditions and the following disclaimer. |
10 * * Redistributions in binary form must reproduce the above | 10 * * Redistributions in binary form must reproduce the above |
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24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
29 * | 29 * |
30 * --- | 30 * --- |
31 * This file is a Linux-specific part of spinlock_internal.cc | 31 * This file is a Linux-specific part of spinlock_internal.cc |
32 */ | 32 */ |
33 | 33 |
34 #include <errno.h> | |
35 #include <sched.h> | 34 #include <sched.h> |
36 #include <time.h> | 35 #include <time.h> |
37 #include <limits.h> | 36 #include <limits.h> |
38 #include "base/linux_syscall_support.h" | 37 #include "base/linux_syscall_support.h" |
39 | 38 |
40 #define FUTEX_WAIT 0 | 39 #define FUTEX_WAIT 0 |
41 #define FUTEX_WAKE 1 | 40 #define FUTEX_WAKE 1 |
42 #define FUTEX_PRIVATE_FLAG 128 | 41 #define FUTEX_PRIVATE_FLAG 128 |
43 | 42 |
44 // Note: Instead of making direct system calls that are inlined, we rely | 43 // Note: Instead of making direct system calls that are inlined, we rely |
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80 | 79 |
81 namespace base { | 80 namespace base { |
82 namespace internal { | 81 namespace internal { |
83 | 82 |
84 void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) { | 83 void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) { |
85 if (loop != 0) { | 84 if (loop != 0) { |
86 int save_errno = errno; | 85 int save_errno = errno; |
87 struct timespec tm; | 86 struct timespec tm; |
88 tm.tv_sec = 0; | 87 tm.tv_sec = 0; |
89 if (have_futex) { | 88 if (have_futex) { |
90 tm.tv_nsec = base::internal::SuggestedDelayNS(loop); | 89 tm.tv_nsec = 1000000; // 1ms; really we're trying to sleep for one |
| 90 // kernel clock tick |
91 } else { | 91 } else { |
92 tm.tv_nsec = 2000001; // above 2ms so linux 2.4 doesn't spin | 92 tm.tv_nsec = 2000001; // above 2ms so linux 2.4 doesn't spin |
93 } | 93 } |
94 if (have_futex) { | 94 if (have_futex) { |
95 tm.tv_nsec *= 16; // increase the delay; we expect explicit wakeups | |
96 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), | 95 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), |
97 FUTEX_WAIT | futex_private_flag, | 96 FUTEX_WAIT | futex_private_flag, |
98 value, reinterpret_cast<struct kernel_timespec *>(&tm)); | 97 value, reinterpret_cast<struct kernel_timespec *>(&tm)); |
99 } else { | 98 } else { |
100 nanosleep(&tm, NULL); | 99 nanosleep(&tm, NULL); |
101 } | 100 } |
102 errno = save_errno; | 101 errno = save_errno; |
103 } | 102 } |
104 } | 103 } |
105 | 104 |
106 void SpinLockWake(volatile Atomic32 *w, bool all) { | 105 void SpinLockWake(volatile Atomic32 *w, bool all) { |
107 if (have_futex) { | 106 if (have_futex) { |
108 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), | 107 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), |
109 FUTEX_WAKE | futex_private_flag, 1, 0); | 108 FUTEX_WAKE | futex_private_flag, 1, 0); |
110 } | 109 } |
111 } | 110 } |
112 | 111 |
113 } // namespace internal | 112 } // namespace internal |
114 } // namespace base | 113 } // namespace base |
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