1 | // |
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2 | // Cforall Version 1.0.0 Copyright (C) 2019 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 | // ready_queue.cfa -- |
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8 | // |
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9 | // Author : Thierry Delisle |
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10 | // Created On : Mon Nov dd 16:29:18 2019 |
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11 | // Last Modified By : |
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12 | // Last Modified On : |
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13 | // Update Count : |
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14 | // |
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15 | |
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16 | #define __cforall_thread__ |
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17 | // #define __CFA_DEBUG_PRINT_READY_QUEUE__ |
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18 | |
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19 | #include "bits/defs.hfa" |
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20 | #include "kernel_private.hfa" |
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21 | |
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22 | #define _GNU_SOURCE |
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23 | #include "stdlib.hfa" |
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24 | #include "math.hfa" |
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25 | |
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26 | #include <unistd.h> |
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27 | |
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28 | static const size_t cache_line_size = 64; |
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29 | |
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30 | // No overriden function, no environment variable, no define |
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31 | // fall back to a magic number |
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32 | #ifndef __CFA_MAX_PROCESSORS__ |
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33 | #define __CFA_MAX_PROCESSORS__ 1024 |
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34 | #endif |
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35 | |
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36 | #define BIAS 64 |
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37 | |
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38 | // returns the maximum number of processors the RWLock support |
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39 | __attribute__((weak)) unsigned __max_processors() { |
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40 | const char * max_cores_s = getenv("CFA_MAX_PROCESSORS"); |
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41 | if(!max_cores_s) { |
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42 | __cfadbg_print_nolock(ready_queue, "No CFA_MAX_PROCESSORS in ENV\n"); |
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43 | return __CFA_MAX_PROCESSORS__; |
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44 | } |
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45 | |
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46 | char * endptr = 0p; |
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47 | long int max_cores_l = strtol(max_cores_s, &endptr, 10); |
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48 | if(max_cores_l < 1 || max_cores_l > 65535) { |
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49 | __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS out of range : %ld\n", max_cores_l); |
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50 | return __CFA_MAX_PROCESSORS__; |
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51 | } |
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52 | if('\0' != *endptr) { |
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53 | __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS not a decimal number : %s\n", max_cores_s); |
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54 | return __CFA_MAX_PROCESSORS__; |
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55 | } |
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56 | |
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57 | return max_cores_l; |
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58 | } |
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59 | |
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60 | //======================================================================= |
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61 | // Cluster wide reader-writer lock |
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62 | //======================================================================= |
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63 | void ?{}(__scheduler_RWLock_t & this) { |
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64 | this.max = __max_processors(); |
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65 | this.alloc = 0; |
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66 | this.ready = 0; |
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67 | this.lock = false; |
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68 | this.data = alloc(this.max); |
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69 | |
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70 | /*paranoid*/ verify( 0 == (((uintptr_t)(this.data )) % 64) ); |
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71 | /*paranoid*/ verify( 0 == (((uintptr_t)(this.data + 1)) % 64) ); |
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72 | /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.alloc), &this.alloc)); |
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73 | /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.ready), &this.ready)); |
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74 | |
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75 | } |
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76 | void ^?{}(__scheduler_RWLock_t & this) { |
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77 | free(this.data); |
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78 | } |
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79 | |
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80 | void ?{}( __scheduler_lock_id_t & this, __processor_id_t * proc ) { |
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81 | this.handle = proc; |
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82 | this.lock = false; |
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83 | #ifdef __CFA_WITH_VERIFY__ |
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84 | this.owned = false; |
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85 | #endif |
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86 | } |
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87 | |
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88 | //======================================================================= |
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89 | // Lock-Free registering/unregistering of threads |
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90 | unsigned doregister( struct __processor_id_t * proc ) with(*__scheduler_lock) { |
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91 | __cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p for RW-Lock\n", proc); |
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92 | |
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93 | // Step - 1 : check if there is already space in the data |
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94 | uint_fast32_t s = ready; |
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95 | |
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96 | // Check among all the ready |
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97 | for(uint_fast32_t i = 0; i < s; i++) { |
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98 | __processor_id_t * null = 0p; // Re-write every loop since compare thrashes it |
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99 | if( __atomic_load_n(&data[i].handle, (int)__ATOMIC_RELAXED) == null |
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100 | && __atomic_compare_exchange_n( &data[i].handle, &null, proc, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) { |
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101 | /*paranoid*/ verify(i < ready); |
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102 | /*paranoid*/ verify(0 == (__alignof__(data[i]) % cache_line_size)); |
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103 | /*paranoid*/ verify((((uintptr_t)&data[i]) % cache_line_size) == 0); |
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104 | return i; |
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105 | } |
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106 | } |
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107 | |
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108 | if(max <= alloc) abort("Trying to create more than %ud processors", __scheduler_lock->max); |
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109 | |
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110 | // Step - 2 : F&A to get a new spot in the array. |
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111 | uint_fast32_t n = __atomic_fetch_add(&alloc, 1, __ATOMIC_SEQ_CST); |
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112 | if(max <= n) abort("Trying to create more than %ud processors", __scheduler_lock->max); |
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113 | |
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114 | // Step - 3 : Mark space as used and then publish it. |
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115 | __scheduler_lock_id_t * storage = (__scheduler_lock_id_t *)&data[n]; |
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116 | (*storage){ proc }; |
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117 | while(true) { |
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118 | unsigned copy = n; |
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119 | if( __atomic_load_n(&ready, __ATOMIC_RELAXED) == n |
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120 | && __atomic_compare_exchange_n(&ready, ©, n + 1, true, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) |
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121 | break; |
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122 | asm volatile("pause"); |
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123 | } |
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124 | |
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125 | __cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p done, id %lu\n", proc, n); |
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126 | |
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127 | // Return new spot. |
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128 | /*paranoid*/ verify(n < ready); |
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129 | /*paranoid*/ verify(__alignof__(data[n]) == (2 * cache_line_size)); |
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130 | /*paranoid*/ verify((((uintptr_t)&data[n]) % cache_line_size) == 0); |
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131 | return n; |
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132 | } |
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133 | |
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134 | void unregister( struct __processor_id_t * proc ) with(*__scheduler_lock) { |
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135 | unsigned id = proc->id; |
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136 | /*paranoid*/ verify(id < ready); |
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137 | /*paranoid*/ verify(proc == __atomic_load_n(&data[id].handle, __ATOMIC_RELAXED)); |
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138 | __atomic_store_n(&data[id].handle, 0p, __ATOMIC_RELEASE); |
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139 | |
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140 | __cfadbg_print_safe(ready_queue, "Kernel : Unregister proc %p\n", proc); |
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141 | } |
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142 | |
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143 | //----------------------------------------------------------------------- |
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144 | // Writer side : acquire when changing the ready queue, e.g. adding more |
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145 | // queues or removing them. |
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146 | uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) { |
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147 | // Step 1 : lock global lock |
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148 | // It is needed to avoid processors that register mid Critical-Section |
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149 | // to simply lock their own lock and enter. |
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150 | __atomic_acquire( &lock ); |
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151 | |
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152 | // Step 2 : lock per-proc lock |
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153 | // Processors that are currently being registered aren't counted |
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154 | // but can't be in read_lock or in the critical section. |
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155 | // All other processors are counted |
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156 | uint_fast32_t s = ready; |
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157 | for(uint_fast32_t i = 0; i < s; i++) { |
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158 | __atomic_acquire( &data[i].lock ); |
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159 | } |
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160 | |
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161 | return s; |
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162 | } |
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163 | |
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164 | void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) { |
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165 | // Step 1 : release local locks |
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166 | // This must be done while the global lock is held to avoid |
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167 | // threads that where created mid critical section |
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168 | // to race to lock their local locks and have the writer |
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169 | // immidiately unlock them |
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170 | // Alternative solution : return s in write_lock and pass it to write_unlock |
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171 | for(uint_fast32_t i = 0; i < last_s; i++) { |
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172 | verify(data[i].lock); |
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173 | __atomic_store_n(&data[i].lock, (bool)false, __ATOMIC_RELEASE); |
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174 | } |
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175 | |
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176 | // Step 2 : release global lock |
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177 | /*paranoid*/ assert(true == lock); |
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178 | __atomic_store_n(&lock, (bool)false, __ATOMIC_RELEASE); |
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179 | } |
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180 | |
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181 | //======================================================================= |
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182 | // Intrusive Queue used by ready queue |
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183 | //======================================================================= |
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184 | // Intrusives lanes which are used by the relaxed ready queue |
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185 | struct __attribute__((aligned(128))) __intrusive_lane_t { |
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186 | // spin lock protecting the queue |
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187 | volatile bool lock; |
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188 | |
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189 | // anchor for the head and the tail of the queue |
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190 | struct __sentinel_t { |
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191 | // Link lists fields |
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192 | // instrusive link field for threads |
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193 | // must be exactly as in $thread |
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194 | __thread_desc_link link; |
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195 | } before, after; |
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196 | |
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197 | // Optional statistic counters |
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198 | #if !defined(__CFA_NO_SCHED_STATS__) |
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199 | struct __attribute__((aligned(64))) { |
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200 | // difference between number of push and pops |
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201 | ssize_t diff; |
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202 | |
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203 | // total number of pushes and pops |
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204 | size_t push; |
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205 | size_t pop ; |
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206 | } stat; |
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207 | #endif |
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208 | }; |
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209 | |
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210 | void ?{}(__intrusive_lane_t & this); |
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211 | void ^?{}(__intrusive_lane_t & this); |
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212 | |
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213 | // Get the head pointer (one before the first element) from the anchor |
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214 | static inline $thread * head(const __intrusive_lane_t & this) { |
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215 | $thread * rhead = ($thread *)( |
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216 | (uintptr_t)( &this.before ) - offsetof( $thread, link ) |
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217 | ); |
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218 | /* paranoid */ verify(rhead); |
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219 | return rhead; |
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220 | } |
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221 | |
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222 | // Get the tail pointer (one after the last element) from the anchor |
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223 | static inline $thread * tail(const __intrusive_lane_t & this) { |
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224 | $thread * rtail = ($thread *)( |
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225 | (uintptr_t)( &this.after ) - offsetof( $thread, link ) |
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226 | ); |
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227 | /* paranoid */ verify(rtail); |
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228 | return rtail; |
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229 | } |
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230 | |
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231 | // Ctor |
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232 | void ?{}( __intrusive_lane_t & this ) { |
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233 | this.lock = false; |
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234 | |
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235 | this.before.link.prev = 0p; |
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236 | this.before.link.next = tail(this); |
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237 | this.before.link.ts = 0; |
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238 | |
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239 | this.after .link.prev = head(this); |
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240 | this.after .link.next = 0p; |
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241 | this.after .link.ts = 0; |
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242 | |
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243 | #if !defined(__CFA_NO_SCHED_STATS__) |
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244 | this.stat.diff = 0; |
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245 | this.stat.push = 0; |
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246 | this.stat.pop = 0; |
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247 | #endif |
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248 | |
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249 | // We add a boat-load of assertions here because the anchor code is very fragile |
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250 | /* paranoid */ verify(((uintptr_t)( head(this) ) + offsetof( $thread, link )) == (uintptr_t)(&this.before)); |
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251 | /* paranoid */ verify(((uintptr_t)( tail(this) ) + offsetof( $thread, link )) == (uintptr_t)(&this.after )); |
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252 | /* paranoid */ verify(head(this)->link.prev == 0p ); |
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253 | /* paranoid */ verify(head(this)->link.next == tail(this) ); |
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254 | /* paranoid */ verify(tail(this)->link.next == 0p ); |
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255 | /* paranoid */ verify(tail(this)->link.prev == head(this) ); |
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256 | /* paranoid */ verify(&head(this)->link.prev == &this.before.link.prev ); |
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257 | /* paranoid */ verify(&head(this)->link.next == &this.before.link.next ); |
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258 | /* paranoid */ verify(&tail(this)->link.prev == &this.after .link.prev ); |
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259 | /* paranoid */ verify(&tail(this)->link.next == &this.after .link.next ); |
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260 | /* paranoid */ verify(sizeof(__intrusive_lane_t) == 128); |
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261 | /* paranoid */ verify(sizeof(this) == 128); |
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262 | /* paranoid */ verify(__alignof__(__intrusive_lane_t) == 128); |
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263 | /* paranoid */ verify(__alignof__(this) == 128); |
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264 | /* paranoid */ verifyf(((intptr_t)(&this) % 128) == 0, "Expected address to be aligned %p %% 128 == %zd", &this, ((intptr_t)(&this) % 128)); |
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265 | } |
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266 | |
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267 | // Dtor is trivial |
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268 | void ^?{}( __intrusive_lane_t & this ) { |
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269 | // Make sure the list is empty |
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270 | /* paranoid */ verify(head(this)->link.prev == 0p ); |
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271 | /* paranoid */ verify(head(this)->link.next == tail(this) ); |
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272 | /* paranoid */ verify(tail(this)->link.next == 0p ); |
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273 | /* paranoid */ verify(tail(this)->link.prev == head(this) ); |
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274 | } |
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275 | |
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276 | // Push a thread onto this lane |
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277 | // returns true of lane was empty before push, false otherwise |
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278 | bool push(__intrusive_lane_t & this, $thread * node) { |
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279 | #if defined(__CFA_WITH_VERIFY__) |
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280 | /* paranoid */ verify(this.lock); |
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281 | /* paranoid */ verify(node->link.ts != 0); |
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282 | /* paranoid */ verify(node->link.next == 0p); |
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283 | /* paranoid */ verify(node->link.prev == 0p); |
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284 | /* paranoid */ verify(tail(this)->link.next == 0p); |
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285 | /* paranoid */ verify(head(this)->link.prev == 0p); |
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286 | |
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287 | if(this.before.link.ts == 0l) { |
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288 | /* paranoid */ verify(tail(this)->link.prev == head(this)); |
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289 | /* paranoid */ verify(head(this)->link.next == tail(this)); |
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290 | } else { |
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291 | /* paranoid */ verify(tail(this)->link.prev != head(this)); |
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292 | /* paranoid */ verify(head(this)->link.next != tail(this)); |
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293 | } |
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294 | #endif |
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295 | |
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296 | // Get the relevant nodes locally |
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297 | $thread * tail = tail(this); |
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298 | $thread * prev = tail->link.prev; |
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299 | |
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300 | // Do the push |
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301 | node->link.next = tail; |
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302 | node->link.prev = prev; |
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303 | prev->link.next = node; |
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304 | tail->link.prev = node; |
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305 | |
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306 | // Update stats |
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307 | #if !defined(__CFA_NO_SCHED_STATS__) |
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308 | this.stat.diff++; |
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309 | this.stat.push++; |
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310 | #endif |
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311 | |
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312 | verify(node->link.next == tail(this)); |
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313 | |
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314 | // Check if the queue used to be empty |
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315 | if(this.before.link.ts == 0l) { |
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316 | this.before.link.ts = node->link.ts; |
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317 | /* paranoid */ verify(node->link.prev == head(this)); |
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318 | return true; |
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319 | } |
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320 | return false; |
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321 | } |
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322 | |
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323 | // Pop a thread from this lane (must be non-empty) |
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324 | // returns popped |
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325 | // returns true of lane was empty before push, false otherwise |
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326 | [$thread *, bool] pop(__intrusive_lane_t & this) { |
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327 | /* paranoid */ verify(this.lock); |
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328 | /* paranoid */ verify(this.before.link.ts != 0ul); |
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329 | |
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330 | // Get anchors locally |
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331 | $thread * head = head(this); |
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332 | $thread * tail = tail(this); |
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333 | |
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334 | // Get the relevant nodes locally |
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335 | $thread * node = head->link.next; |
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336 | $thread * next = node->link.next; |
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337 | |
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338 | /* paranoid */ verify(node != tail); |
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339 | /* paranoid */ verify(node); |
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340 | |
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341 | // Do the pop |
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342 | head->link.next = next; |
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343 | next->link.prev = head; |
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344 | node->link.[next, prev] = 0p; |
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345 | |
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346 | // Update head time stamp |
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347 | this.before.link.ts = next->link.ts; |
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348 | |
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349 | // Update stats |
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350 | #ifndef __CFA_NO_SCHED_STATS__ |
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351 | this.stat.diff--; |
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352 | this.stat.pop ++; |
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353 | #endif |
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354 | |
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355 | // Check if we emptied list and return accordingly |
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356 | /* paranoid */ verify(tail(this)->link.next == 0p); |
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357 | /* paranoid */ verify(head(this)->link.prev == 0p); |
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358 | if(next == tail) { |
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359 | /* paranoid */ verify(this.before.link.ts == 0); |
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360 | /* paranoid */ verify(tail(this)->link.prev == head(this)); |
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361 | /* paranoid */ verify(head(this)->link.next == tail(this)); |
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362 | return [node, true]; |
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363 | } |
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364 | else { |
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365 | /* paranoid */ verify(next->link.ts != 0); |
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366 | /* paranoid */ verify(tail(this)->link.prev != head(this)); |
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367 | /* paranoid */ verify(head(this)->link.next != tail(this)); |
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368 | /* paranoid */ verify(this.before.link.ts != 0); |
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369 | return [node, false]; |
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370 | } |
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371 | } |
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372 | |
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373 | // Check whether or not list is empty |
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374 | static inline bool is_empty(__intrusive_lane_t & this) { |
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375 | // Cannot verify here since it may not be locked |
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376 | return this.before.link.ts == 0; |
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377 | } |
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378 | |
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379 | // Return the timestamp |
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380 | static inline unsigned long long ts(__intrusive_lane_t & this) { |
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381 | // Cannot verify here since it may not be locked |
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382 | return this.before.link.ts; |
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383 | } |
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384 | |
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385 | //======================================================================= |
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386 | // Scalable Non-Zero counter |
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387 | //======================================================================= |
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388 | |
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389 | union __snzi_val_t { |
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390 | uint64_t _all; |
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391 | struct __attribute__((packed)) { |
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392 | char cnt; |
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393 | uint64_t ver:56; |
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394 | }; |
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395 | }; |
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396 | |
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397 | bool cas(volatile __snzi_val_t & self, __snzi_val_t & exp, char _cnt, uint64_t _ver) { |
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398 | __snzi_val_t t; |
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399 | t.ver = _ver; |
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400 | t.cnt = _cnt; |
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401 | /* paranoid */ verify(t._all == ((_ver << 8) | ((unsigned char)_cnt))); |
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402 | return __atomic_compare_exchange_n(&self._all, &exp._all, t._all, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); |
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403 | } |
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404 | |
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405 | bool cas(volatile __snzi_val_t & self, __snzi_val_t & exp, const __snzi_val_t & tar) { |
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406 | return __atomic_compare_exchange_n(&self._all, &exp._all, tar._all, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); |
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407 | } |
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408 | |
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409 | void ?{}( __snzi_val_t & this ) { this._all = 0; } |
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410 | void ?{}( __snzi_val_t & this, const volatile __snzi_val_t & o) { this._all = o._all; } |
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411 | |
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412 | struct __attribute__((aligned(128))) __snzi_node_t { |
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413 | volatile __snzi_val_t value; |
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414 | struct __snzi_node_t * parent; |
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415 | bool is_root; |
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416 | }; |
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417 | |
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418 | static inline void arrive( __snzi_node_t & ); |
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419 | static inline void depart( __snzi_node_t & ); |
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420 | |
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421 | #define __snzi_half -1 |
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422 | |
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423 | //-------------------------------------------------- |
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424 | // Root node |
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425 | static void arrive_r( __snzi_node_t & this ) { |
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426 | /* paranoid */ verify( this.is_root ); |
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427 | __atomic_fetch_add(&this.value._all, 1, __ATOMIC_SEQ_CST); |
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428 | } |
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429 | |
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430 | static void depart_r( __snzi_node_t & this ) { |
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431 | /* paranoid */ verify( this.is_root ); |
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432 | __atomic_fetch_sub(&this.value._all, 1, __ATOMIC_SEQ_CST); |
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433 | } |
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434 | |
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435 | //-------------------------------------------------- |
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436 | // Hierarchical node |
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437 | static void arrive_h( __snzi_node_t & this ) { |
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438 | int undoArr = 0; |
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439 | bool success = false; |
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440 | while(!success) { |
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441 | __snzi_val_t x = { this.value }; |
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442 | /* paranoid */ verify(x.cnt <= 120); |
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443 | if( x.cnt >= 1 ) { |
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444 | if( cas( this.value, x, x.cnt + 1, x.ver ) ) { |
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445 | success = true; |
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446 | } |
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447 | } |
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448 | /* paranoid */ verify(x.cnt <= 120); |
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449 | if( x.cnt == 0 ) { |
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450 | if( cas( this.value, x, __snzi_half, x.ver + 1) ) { |
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451 | success = true; |
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452 | x.cnt = __snzi_half; |
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453 | x.ver = x.ver + 1; |
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454 | } |
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455 | } |
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456 | /* paranoid */ verify(x.cnt <= 120); |
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457 | if( x.cnt == __snzi_half ) { |
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458 | /* paranoid */ verify( this.parent); |
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459 | arrive( *this.parent ); |
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460 | if( !cas( this.value, x, 1, x.ver) ) { |
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461 | undoArr = undoArr + 1; |
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462 | } |
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463 | } |
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464 | } |
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465 | |
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466 | for(int i = 0; i < undoArr; i++) { |
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467 | /* paranoid */ verify( this.parent ); |
---|
468 | depart( *this.parent ); |
---|
469 | } |
---|
470 | } |
---|
471 | |
---|
472 | static void depart_h( __snzi_node_t & this ) { |
---|
473 | while(true) { |
---|
474 | const __snzi_val_t x = { this.value }; |
---|
475 | /* paranoid */ verifyf(x.cnt >= 1, "%d", x.cnt); |
---|
476 | if( cas( this.value, x, x.cnt - 1, x.ver ) ) { |
---|
477 | if( x.cnt == 1 ) { |
---|
478 | /* paranoid */ verify( this.parent ); |
---|
479 | depart( *this.parent ); |
---|
480 | } |
---|
481 | return; |
---|
482 | } |
---|
483 | } |
---|
484 | } |
---|
485 | |
---|
486 | //-------------------------------------------------- |
---|
487 | // All nodes |
---|
488 | static inline void arrive( __snzi_node_t & this ) { |
---|
489 | if(this.is_root) arrive_r( this ); |
---|
490 | else arrive_h( this ); |
---|
491 | } |
---|
492 | |
---|
493 | static inline void depart( __snzi_node_t & this ) { |
---|
494 | if(this.is_root) depart_r( this ); |
---|
495 | else depart_h( this ); |
---|
496 | } |
---|
497 | |
---|
498 | static inline bool query( __snzi_node_t & this ) { |
---|
499 | /* paranoid */ verify( this.is_root ); |
---|
500 | return this.value._all > 0; |
---|
501 | } |
---|
502 | |
---|
503 | //-------------------------------------------------- |
---|
504 | // SNZI object |
---|
505 | void ?{}( __snzi_t & this, unsigned depth ) with( this ) { |
---|
506 | mask = (1 << depth) - 1; |
---|
507 | root = (1 << (depth + 1)) - 2; |
---|
508 | nodes = alloc( root + 1 ); |
---|
509 | |
---|
510 | int width = 1 << depth; |
---|
511 | for(int i = 0; i < root; i++) { |
---|
512 | nodes[i].value._all = 0; |
---|
513 | nodes[i].parent = &nodes[(i / 2) + width ]; |
---|
514 | nodes[i].is_root = false; |
---|
515 | } |
---|
516 | |
---|
517 | nodes[ root ].value._all = 0; |
---|
518 | nodes[ root ].parent = 0p; |
---|
519 | nodes[ root ].is_root = true; |
---|
520 | } |
---|
521 | |
---|
522 | void ^?{}( __snzi_t & this ) { |
---|
523 | free( this.nodes ); |
---|
524 | } |
---|
525 | |
---|
526 | static inline void arrive( __snzi_t & this, int idx) { |
---|
527 | idx &= this.mask; |
---|
528 | arrive( this.nodes[idx] ); |
---|
529 | } |
---|
530 | |
---|
531 | static inline void depart( __snzi_t & this, int idx) { |
---|
532 | idx &= this.mask; |
---|
533 | depart( this.nodes[idx] ); |
---|
534 | } |
---|
535 | |
---|
536 | static inline bool query( const __snzi_t & this ) { |
---|
537 | return query( this.nodes[ this.root ] ); |
---|
538 | } |
---|
539 | |
---|
540 | //======================================================================= |
---|
541 | // Cforall Reqdy Queue used by ready queue |
---|
542 | //======================================================================= |
---|
543 | |
---|
544 | void ?{}(__ready_queue_t & this) with (this) { |
---|
545 | |
---|
546 | lanes.data = alloc(4); |
---|
547 | for( i; 4 ) { |
---|
548 | (lanes.data[i]){}; |
---|
549 | } |
---|
550 | lanes.count = 4; |
---|
551 | snzi{ log2( lanes.count / 8 ) }; |
---|
552 | } |
---|
553 | |
---|
554 | void ^?{}(__ready_queue_t & this) with (this) { |
---|
555 | verify( 4 == lanes.count ); |
---|
556 | verify( !query( snzi ) ); |
---|
557 | |
---|
558 | ^(snzi){}; |
---|
559 | |
---|
560 | for( i; 4 ) { |
---|
561 | ^(lanes.data[i]){}; |
---|
562 | } |
---|
563 | free(lanes.data); |
---|
564 | } |
---|
565 | |
---|
566 | //----------------------------------------------------------------------- |
---|
567 | __attribute__((hot)) bool query(struct cluster * cltr) { |
---|
568 | return query(cltr->ready_queue.snzi); |
---|
569 | } |
---|
570 | |
---|
571 | //----------------------------------------------------------------------- |
---|
572 | __attribute__((hot)) bool push(struct cluster * cltr, struct $thread * thrd) with (cltr->ready_queue) { |
---|
573 | __cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr); |
---|
574 | |
---|
575 | // write timestamp |
---|
576 | thrd->link.ts = rdtscl(); |
---|
577 | |
---|
578 | // Try to pick a lane and lock it |
---|
579 | unsigned i; |
---|
580 | do { |
---|
581 | // Pick the index of a lane |
---|
582 | #if defined(BIAS) |
---|
583 | unsigned r = __tls_rand(); |
---|
584 | unsigned rlow = r % BIAS; |
---|
585 | unsigned rhigh = r / BIAS; |
---|
586 | if(0 != (rlow % BIAS) && kernelTLS.this_processor) { |
---|
587 | // (BIAS - 1) out of BIAS chances |
---|
588 | // Use perferred queues |
---|
589 | i = (kernelTLS.this_processor->id * 4) + (rhigh % 4); |
---|
590 | } |
---|
591 | else { |
---|
592 | // 1 out of BIAS chances |
---|
593 | // Use all queues |
---|
594 | i = rhigh; |
---|
595 | } |
---|
596 | #else |
---|
597 | i = __tls_rand(); |
---|
598 | #endif |
---|
599 | |
---|
600 | i %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED ); |
---|
601 | |
---|
602 | #if !defined(__CFA_NO_STATISTICS__) |
---|
603 | __tls_stats()->ready.pick.push.attempt++; |
---|
604 | #endif |
---|
605 | |
---|
606 | // If we can't lock it retry |
---|
607 | } while( !__atomic_try_acquire( &lanes.data[i].lock ) ); |
---|
608 | |
---|
609 | bool first = false; |
---|
610 | |
---|
611 | // Actually push it |
---|
612 | bool lane_first = push(lanes.data[i], thrd); |
---|
613 | |
---|
614 | // If this lane used to be empty we need to do more |
---|
615 | if(lane_first) { |
---|
616 | // Check if the entire queue used to be empty |
---|
617 | first = !query(snzi); |
---|
618 | |
---|
619 | // Update the snzi |
---|
620 | arrive( snzi, i ); |
---|
621 | } |
---|
622 | |
---|
623 | // Unlock and return |
---|
624 | __atomic_unlock( &lanes.data[i].lock ); |
---|
625 | |
---|
626 | __cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first); |
---|
627 | |
---|
628 | // Update statistics |
---|
629 | #if !defined(__CFA_NO_STATISTICS__) |
---|
630 | __tls_stats()->ready.pick.push.success++; |
---|
631 | #endif |
---|
632 | |
---|
633 | // return whether or not the list was empty before this push |
---|
634 | return first; |
---|
635 | } |
---|
636 | |
---|
637 | //----------------------------------------------------------------------- |
---|
638 | // Given 2 indexes, pick the list with the oldest push an try to pop from it |
---|
639 | static struct $thread * try_pop(struct cluster * cltr, unsigned i, unsigned j) with (cltr->ready_queue) { |
---|
640 | #if !defined(__CFA_NO_STATISTICS__) |
---|
641 | __tls_stats()->ready.pick.pop.attempt++; |
---|
642 | #endif |
---|
643 | |
---|
644 | // Pick the bet list |
---|
645 | int w = i; |
---|
646 | if( __builtin_expect(!is_empty(lanes.data[j]), true) ) { |
---|
647 | w = (ts(lanes.data[i]) < ts(lanes.data[j])) ? i : j; |
---|
648 | } |
---|
649 | |
---|
650 | // Get relevant elements locally |
---|
651 | __intrusive_lane_t & lane = lanes.data[w]; |
---|
652 | |
---|
653 | // If list looks empty retry |
---|
654 | if( is_empty(lane) ) return 0p; |
---|
655 | |
---|
656 | // If we can't get the lock retry |
---|
657 | if( !__atomic_try_acquire(&lane.lock) ) return 0p; |
---|
658 | |
---|
659 | |
---|
660 | // If list is empty, unlock and retry |
---|
661 | if( is_empty(lane) ) { |
---|
662 | __atomic_unlock(&lane.lock); |
---|
663 | return 0p; |
---|
664 | } |
---|
665 | |
---|
666 | // Actually pop the list |
---|
667 | struct $thread * thrd; |
---|
668 | bool emptied; |
---|
669 | [thrd, emptied] = pop(lane); |
---|
670 | |
---|
671 | /* paranoid */ verify(thrd); |
---|
672 | /* paranoid */ verify(lane.lock); |
---|
673 | |
---|
674 | // If this was the last element in the lane |
---|
675 | if(emptied) { |
---|
676 | depart( snzi, w ); |
---|
677 | } |
---|
678 | |
---|
679 | // Unlock and return |
---|
680 | __atomic_unlock(&lane.lock); |
---|
681 | |
---|
682 | // Update statistics |
---|
683 | #if !defined(__CFA_NO_STATISTICS__) |
---|
684 | __tls_stats()->ready.pick.pop.success++; |
---|
685 | #endif |
---|
686 | |
---|
687 | // return the popped thread |
---|
688 | return thrd; |
---|
689 | } |
---|
690 | |
---|
691 | // Pop from the ready queue from a given cluster |
---|
692 | __attribute__((hot)) $thread * pop(struct cluster * cltr) with (cltr->ready_queue) { |
---|
693 | /* paranoid */ verify( lanes.count > 0 ); |
---|
694 | |
---|
695 | // As long as the list is not empty, try finding a lane that isn't empty and pop from it |
---|
696 | while( query(snzi) ) { |
---|
697 | // Pick two lists at random |
---|
698 | #if defined(BIAS) |
---|
699 | unsigned i = __tls_rand(); |
---|
700 | unsigned j = __tls_rand(); |
---|
701 | |
---|
702 | if(0 == (i % BIAS)) { |
---|
703 | i = i / BIAS; |
---|
704 | } |
---|
705 | else { |
---|
706 | i = ((kernelTLS.this_processor->id * 4) + ((i / BIAS) % 4)); |
---|
707 | j = ((kernelTLS.this_processor->id * 4) + ((j / BIAS) % 4)); |
---|
708 | } |
---|
709 | #else |
---|
710 | unsigned i = __tls_rand(); |
---|
711 | unsigned j = __tls_rand(); |
---|
712 | #endif |
---|
713 | |
---|
714 | i %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED ); |
---|
715 | j %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED ); |
---|
716 | |
---|
717 | // try popping from the 2 picked lists |
---|
718 | struct $thread * thrd = try_pop(cltr, i, j); |
---|
719 | if(thrd) return thrd; |
---|
720 | } |
---|
721 | |
---|
722 | // All lanes where empty return 0p |
---|
723 | return 0p; |
---|
724 | } |
---|
725 | |
---|
726 | //----------------------------------------------------------------------- |
---|
727 | |
---|
728 | static void check( __ready_queue_t & q ) with (q) { |
---|
729 | #if defined(__CFA_WITH_VERIFY__) |
---|
730 | { |
---|
731 | for( idx ; lanes.count ) { |
---|
732 | __intrusive_lane_t & sl = lanes.data[idx]; |
---|
733 | assert(!lanes.data[idx].lock); |
---|
734 | |
---|
735 | assert(head(sl)->link.prev == 0p ); |
---|
736 | assert(head(sl)->link.next->link.prev == head(sl) ); |
---|
737 | assert(tail(sl)->link.next == 0p ); |
---|
738 | assert(tail(sl)->link.prev->link.next == tail(sl) ); |
---|
739 | |
---|
740 | if(sl.before.link.ts == 0l) { |
---|
741 | assert(tail(sl)->link.prev == head(sl)); |
---|
742 | assert(head(sl)->link.next == tail(sl)); |
---|
743 | } else { |
---|
744 | assert(tail(sl)->link.prev != head(sl)); |
---|
745 | assert(head(sl)->link.next != tail(sl)); |
---|
746 | } |
---|
747 | } |
---|
748 | } |
---|
749 | #endif |
---|
750 | } |
---|
751 | |
---|
752 | // Call this function of the intrusive list was moved using memcpy |
---|
753 | // fixes the list so that the pointers back to anchors aren't left dangling |
---|
754 | static inline void fix(__intrusive_lane_t & ll) { |
---|
755 | // if the list is not empty then follow he pointer and fix its reverse |
---|
756 | if(!is_empty(ll)) { |
---|
757 | head(ll)->link.next->link.prev = head(ll); |
---|
758 | tail(ll)->link.prev->link.next = tail(ll); |
---|
759 | } |
---|
760 | // Otherwise just reset the list |
---|
761 | else { |
---|
762 | verify(tail(ll)->link.next == 0p); |
---|
763 | tail(ll)->link.prev = head(ll); |
---|
764 | head(ll)->link.next = tail(ll); |
---|
765 | verify(head(ll)->link.prev == 0p); |
---|
766 | } |
---|
767 | } |
---|
768 | |
---|
769 | // Grow the ready queue |
---|
770 | void ready_queue_grow (struct cluster * cltr) { |
---|
771 | /* paranoid */ verify( ready_mutate_islocked() ); |
---|
772 | __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue\n"); |
---|
773 | |
---|
774 | // Make sure that everything is consistent |
---|
775 | /* paranoid */ check( cltr->ready_queue ); |
---|
776 | |
---|
777 | // grow the ready queue |
---|
778 | with( cltr->ready_queue ) { |
---|
779 | ^(snzi){}; |
---|
780 | |
---|
781 | size_t ncount = lanes.count; |
---|
782 | |
---|
783 | // increase count |
---|
784 | ncount += 4; |
---|
785 | |
---|
786 | // Allocate new array (uses realloc and memcpies the data) |
---|
787 | lanes.data = alloc(lanes.data, ncount); |
---|
788 | |
---|
789 | // Fix the moved data |
---|
790 | for( idx; (size_t)lanes.count ) { |
---|
791 | fix(lanes.data[idx]); |
---|
792 | } |
---|
793 | |
---|
794 | // Construct new data |
---|
795 | for( idx; (size_t)lanes.count ~ ncount) { |
---|
796 | (lanes.data[idx]){}; |
---|
797 | } |
---|
798 | |
---|
799 | // Update original |
---|
800 | lanes.count = ncount; |
---|
801 | |
---|
802 | // Re-create the snzi |
---|
803 | snzi{ log2( lanes.count / 8 ) }; |
---|
804 | for( idx; (size_t)lanes.count ) { |
---|
805 | if( !is_empty(lanes.data[idx]) ) { |
---|
806 | arrive(snzi, idx); |
---|
807 | } |
---|
808 | } |
---|
809 | } |
---|
810 | |
---|
811 | // Make sure that everything is consistent |
---|
812 | /* paranoid */ check( cltr->ready_queue ); |
---|
813 | |
---|
814 | __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue done\n"); |
---|
815 | |
---|
816 | /* paranoid */ verify( ready_mutate_islocked() ); |
---|
817 | } |
---|
818 | |
---|
819 | // Shrink the ready queue |
---|
820 | void ready_queue_shrink(struct cluster * cltr) { |
---|
821 | /* paranoid */ verify( ready_mutate_islocked() ); |
---|
822 | __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue\n"); |
---|
823 | |
---|
824 | // Make sure that everything is consistent |
---|
825 | /* paranoid */ check( cltr->ready_queue ); |
---|
826 | |
---|
827 | with( cltr->ready_queue ) { |
---|
828 | ^(snzi){}; |
---|
829 | |
---|
830 | size_t ocount = lanes.count; |
---|
831 | // Check that we have some space left |
---|
832 | if(ocount < 8) abort("Program attempted to destroy more Ready Queues than were created"); |
---|
833 | |
---|
834 | // reduce the actual count so push doesn't use the old queues |
---|
835 | lanes.count -= 4; |
---|
836 | verify(ocount > lanes.count); |
---|
837 | |
---|
838 | // for printing count the number of displaced threads |
---|
839 | #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__) |
---|
840 | __attribute__((unused)) size_t displaced = 0; |
---|
841 | #endif |
---|
842 | |
---|
843 | // redistribute old data |
---|
844 | for( idx; (size_t)lanes.count ~ ocount) { |
---|
845 | // Lock is not strictly needed but makes checking invariants much easier |
---|
846 | __attribute__((unused)) bool locked = __atomic_try_acquire(&lanes.data[idx].lock); |
---|
847 | verify(locked); |
---|
848 | |
---|
849 | // As long as we can pop from this lane to push the threads somewhere else in the queue |
---|
850 | while(!is_empty(lanes.data[idx])) { |
---|
851 | struct $thread * thrd; |
---|
852 | __attribute__((unused)) bool _; |
---|
853 | [thrd, _] = pop(lanes.data[idx]); |
---|
854 | |
---|
855 | push(cltr, thrd); |
---|
856 | |
---|
857 | // for printing count the number of displaced threads |
---|
858 | #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__) |
---|
859 | displaced++; |
---|
860 | #endif |
---|
861 | } |
---|
862 | |
---|
863 | // Unlock the lane |
---|
864 | __atomic_unlock(&lanes.data[idx].lock); |
---|
865 | |
---|
866 | // TODO print the queue statistics here |
---|
867 | |
---|
868 | ^(lanes.data[idx]){}; |
---|
869 | } |
---|
870 | |
---|
871 | __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue displaced %zu threads\n", displaced); |
---|
872 | |
---|
873 | // Allocate new array (uses realloc and memcpies the data) |
---|
874 | lanes.data = alloc(lanes.data, lanes.count); |
---|
875 | |
---|
876 | // Fix the moved data |
---|
877 | for( idx; (size_t)lanes.count ) { |
---|
878 | fix(lanes.data[idx]); |
---|
879 | } |
---|
880 | |
---|
881 | // Re-create the snzi |
---|
882 | snzi{ log2( lanes.count / 8 ) }; |
---|
883 | for( idx; (size_t)lanes.count ) { |
---|
884 | if( !is_empty(lanes.data[idx]) ) { |
---|
885 | arrive(snzi, idx); |
---|
886 | } |
---|
887 | } |
---|
888 | } |
---|
889 | |
---|
890 | // Make sure that everything is consistent |
---|
891 | /* paranoid */ check( cltr->ready_queue ); |
---|
892 | |
---|
893 | __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue done\n"); |
---|
894 | /* paranoid */ verify( ready_mutate_islocked() ); |
---|
895 | } |
---|