[ea7d2b0] | 1 | // |
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
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| 3 | // |
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| 4 | // The contents of this file are covered under the licence agreement in the |
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| 5 | // file "LICENCE" distributed with Cforall. |
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| 6 | // |
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| 7 | // bits/locks.h -- Fast internal locks. |
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| 8 | // |
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| 9 | // Author : Thierry Delisle |
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| 10 | // Created On : Tue Oct 31 15:14:38 2017 |
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| 11 | // Last Modified By : -- |
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| 12 | // Last Modified On : -- |
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| 13 | // Update Count : 0 |
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| 14 | // |
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| 15 | |
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| 16 | #pragma once |
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| 17 | |
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[875a72f] | 18 | #include "bits/debug.h" |
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[ea7d2b0] | 19 | #include "bits/defs.h" |
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| 20 | |
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| 21 | // pause to prevent excess processor bus usage |
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| 22 | #if defined( __sparc ) |
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| 23 | #define Pause() __asm__ __volatile__ ( "rd %ccr,%g0" ) |
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| 24 | #elif defined( __i386 ) || defined( __x86_64 ) |
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| 25 | #define Pause() __asm__ __volatile__ ( "pause" : : : ) |
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| 26 | #else |
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| 27 | #error unsupported architecture |
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| 28 | #endif |
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| 29 | |
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| 30 | #if defined( __i386 ) || defined( __x86_64 ) |
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| 31 | // Intel recommendation |
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| 32 | #define __ALIGN__ __attribute__(( aligned (128) )) |
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| 33 | #elif defined( __sparc ) |
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| 34 | #define __ALIGN__ CALIGN |
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| 35 | #else |
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| 36 | #error unsupported architecture |
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| 37 | #endif |
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| 38 | |
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| 39 | #if defined( __x86_64 ) |
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| 40 | #define __lock_test_and_test_and_set( lock ) (lock) == 0 && __sync_lock_test_and_set_8( &(lock), 1 ) == 0 |
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| 41 | #define __lock_release( lock ) __sync_lock_release_8( &(lock) ); |
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| 42 | #elif defined( __i386 ) |
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| 43 | #define __lock_test_and_test_and_set( lock ) (lock) == 0 && __sync_lock_test_and_set_4( &(lock), 1 ) == 0 |
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| 44 | #define __lock_release( lock ) __sync_lock_release_4( &(lock) ); |
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| 45 | #else |
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| 46 | #error unsupported architecture |
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| 47 | #endif |
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| 48 | |
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| 49 | struct __spinlock_t { |
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| 50 | __ALIGN__ volatile uintptr_t lock; |
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| 51 | #ifdef __CFA_DEBUG__ |
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| 52 | const char * prev_name; |
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| 53 | void* prev_thrd; |
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| 54 | #endif |
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| 55 | } __ALIGN__; |
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| 56 | |
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[0cf5b79] | 57 | #ifdef __cforall |
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[ea7d2b0] | 58 | extern void yield( unsigned int ); |
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| 59 | extern thread_local struct thread_desc * volatile this_thread; |
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| 60 | |
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| 61 | static inline void ?{}( __spinlock_t & this ) { |
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| 62 | this.lock = 0; |
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| 63 | } |
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| 64 | |
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| 65 | // Lock the spinlock, return false if already acquired |
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[36982fc] | 66 | static inline _Bool try_lock ( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) { |
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[ea7d2b0] | 67 | _Bool result = __lock_test_and_test_and_set( this.lock ); |
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[36982fc] | 68 | __cfaabi_dbg_debug_do( |
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[ea7d2b0] | 69 | if( result ) { |
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| 70 | this.prev_name = caller; |
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| 71 | this.prev_thrd = this_thread; |
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| 72 | } |
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| 73 | ) |
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| 74 | return result; |
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| 75 | } |
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| 76 | |
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| 77 | // Lock the spinlock, spin if already acquired |
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[36982fc] | 78 | static inline void lock( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) { |
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[ea7d2b0] | 79 | #ifndef NOEXPBACK |
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| 80 | enum { SPIN_START = 4, SPIN_END = 64 * 1024, }; |
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| 81 | unsigned int spin = SPIN_START; |
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| 82 | #endif |
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| 83 | |
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| 84 | for ( unsigned int i = 1;; i += 1 ) { |
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| 85 | if ( __lock_test_and_test_and_set( this.lock ) ) break; |
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| 86 | #ifndef NOEXPBACK |
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| 87 | // exponential spin |
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| 88 | for ( volatile unsigned int s = 0; s < spin; s += 1 ) Pause(); |
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| 89 | |
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| 90 | // slowly increase by powers of 2 |
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| 91 | if ( i % 64 == 0 ) spin += spin; |
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| 92 | |
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| 93 | // prevent overflow |
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| 94 | if ( spin > SPIN_END ) spin = SPIN_START; |
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| 95 | #else |
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| 96 | Pause(); |
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| 97 | #endif |
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| 98 | } |
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[36982fc] | 99 | __cfaabi_dbg_debug_do( |
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[ea7d2b0] | 100 | this.prev_name = caller; |
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| 101 | this.prev_thrd = this_thread; |
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| 102 | ) |
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| 103 | } |
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| 104 | |
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| 105 | // Lock the spinlock, spin if already acquired |
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[36982fc] | 106 | static inline void lock_yield( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) { |
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[ea7d2b0] | 107 | for ( unsigned int i = 1;; i += 1 ) { |
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| 108 | if ( __lock_test_and_test_and_set( this.lock ) ) break; |
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| 109 | yield( i ); |
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| 110 | } |
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[36982fc] | 111 | __cfaabi_dbg_debug_do( |
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[ea7d2b0] | 112 | this.prev_name = caller; |
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| 113 | this.prev_thrd = this_thread; |
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| 114 | ) |
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| 115 | } |
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| 116 | |
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| 117 | static inline void unlock( __spinlock_t & this ) { |
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| 118 | __lock_release( this.lock ); |
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| 119 | } |
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| 120 | #endif |
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