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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> |
34 #include <sched.h> | 35 #include <sched.h> |
35 #include <time.h> | 36 #include <time.h> |
36 #include <limits.h> | 37 #include <limits.h> |
37 #include "base/linux_syscall_support.h" | 38 #include "base/linux_syscall_support.h" |
38 | 39 |
39 #define FUTEX_WAIT 0 | 40 #define FUTEX_WAIT 0 |
40 #define FUTEX_WAKE 1 | 41 #define FUTEX_WAKE 1 |
41 #define FUTEX_PRIVATE_FLAG 128 | 42 #define FUTEX_PRIVATE_FLAG 128 |
42 | 43 |
43 // Note: Instead of making direct system calls that are inlined, we rely | 44 // Note: Instead of making direct system calls that are inlined, we rely |
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79 | 80 |
80 namespace base { | 81 namespace base { |
81 namespace internal { | 82 namespace internal { |
82 | 83 |
83 void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) { | 84 void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) { |
84 if (loop != 0) { | 85 if (loop != 0) { |
85 int save_errno = errno; | 86 int save_errno = errno; |
86 struct timespec tm; | 87 struct timespec tm; |
87 tm.tv_sec = 0; | 88 tm.tv_sec = 0; |
88 if (have_futex) { | 89 if (have_futex) { |
89 tm.tv_nsec = 1000000; // 1ms; really we're trying to sleep for one | 90 tm.tv_nsec = base::internal::SuggestedDelayNS(loop); |
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 |
95 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), | 96 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), |
96 FUTEX_WAIT | futex_private_flag, | 97 FUTEX_WAIT | futex_private_flag, |
97 value, reinterpret_cast<struct kernel_timespec *>(&tm)); | 98 value, reinterpret_cast<struct kernel_timespec *>(&tm)); |
98 } else { | 99 } else { |
99 nanosleep(&tm, NULL); | 100 nanosleep(&tm, NULL); |
100 } | 101 } |
101 errno = save_errno; | 102 errno = save_errno; |
102 } | 103 } |
103 } | 104 } |
104 | 105 |
105 void SpinLockWake(volatile Atomic32 *w, bool all) { | 106 void SpinLockWake(volatile Atomic32 *w, bool all) { |
106 if (have_futex) { | 107 if (have_futex) { |
107 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), | 108 syscall(__NR_futex, reinterpret_cast<int *>(const_cast<Atomic32 *>(w)), |
108 FUTEX_WAKE | futex_private_flag, 1, 0); | 109 FUTEX_WAKE | futex_private_flag, 1, 0); |
109 } | 110 } |
110 } | 111 } |
111 | 112 |
112 } // namespace internal | 113 } // namespace internal |
113 } // namespace base | 114 } // namespace base |
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