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1 /*
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2 * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_taskqueue.cpp.incl"
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27
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28 bool TaskQueueSuper::peek() {
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29 return _bottom != _age.top();
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30 }
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31
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32 int TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
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33 const int a = 16807;
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34 const int m = 2147483647;
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35 const int q = 127773; /* m div a */
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36 const int r = 2836; /* m mod a */
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37 assert(sizeof(int) == 4, "I think this relies on that");
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38 int seed = *seed0;
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39 int hi = seed / q;
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40 int lo = seed % q;
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41 int test = a * lo - r * hi;
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42 if (test > 0)
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43 seed = test;
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44 else
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45 seed = test + m;
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46 *seed0 = seed;
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47 return seed;
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48 }
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49
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50 ParallelTaskTerminator::
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51 ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
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52 _n_threads(n_threads),
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53 _queue_set(queue_set),
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54 _offered_termination(0) {}
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55
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56 bool ParallelTaskTerminator::peek_in_queue_set() {
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57 return _queue_set->peek();
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58 }
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59
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60 void ParallelTaskTerminator::yield() {
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61 os::yield();
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62 }
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63
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64 void ParallelTaskTerminator::sleep(uint millis) {
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65 os::sleep(Thread::current(), millis, false);
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66 }
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67
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68 bool ParallelTaskTerminator::offer_termination() {
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69 Atomic::inc(&_offered_termination);
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70
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71 juint yield_count = 0;
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72 while (true) {
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73 if (_offered_termination == _n_threads) {
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74 //inner_termination_loop();
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75 return true;
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76 } else {
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77 if (yield_count <= WorkStealingYieldsBeforeSleep) {
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78 yield_count++;
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79 yield();
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80 } else {
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81 if (PrintGCDetails && Verbose) {
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82 gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
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83 "thread %d sleeps after %d yields",
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84 Thread::current(), yield_count);
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85 }
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86 yield_count = 0;
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87 // A sleep will cause this processor to seek work on another processor's
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88 // runqueue, if it has nothing else to run (as opposed to the yield
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89 // which may only move the thread to the end of the this processor's
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90 // runqueue).
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91 sleep(WorkStealingSleepMillis);
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92 }
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93
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94 if (peek_in_queue_set()) {
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95 Atomic::dec(&_offered_termination);
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96 return false;
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97 }
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98 }
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99 }
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100 }
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101
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102 void ParallelTaskTerminator::reset_for_reuse() {
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103 if (_offered_termination != 0) {
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104 assert(_offered_termination == _n_threads,
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105 "Terminator may still be in use");
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106 _offered_termination = 0;
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107 }
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108 }
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109
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110 bool ChunkTaskQueueWithOverflow::is_empty() {
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111 return (_chunk_queue.size() == 0) &&
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112 (_overflow_stack->length() == 0);
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113 }
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114
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115 bool ChunkTaskQueueWithOverflow::stealable_is_empty() {
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116 return _chunk_queue.size() == 0;
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117 }
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118
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119 bool ChunkTaskQueueWithOverflow::overflow_is_empty() {
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120 return _overflow_stack->length() == 0;
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121 }
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122
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123 void ChunkTaskQueueWithOverflow::initialize() {
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124 _chunk_queue.initialize();
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125 assert(_overflow_stack == 0, "Creating memory leak");
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126 _overflow_stack =
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127 new (ResourceObj::C_HEAP) GrowableArray<ChunkTask>(10, true);
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128 }
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129
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130 void ChunkTaskQueueWithOverflow::save(ChunkTask t) {
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131 if (TraceChunkTasksQueuing && Verbose) {
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132 gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
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133 }
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134 if(!_chunk_queue.push(t)) {
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135 _overflow_stack->push(t);
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136 }
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137 }
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138
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139 // Note that using this method will retrieve all chunks
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140 // that have been saved but that it will always check
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141 // the overflow stack. It may be more efficient to
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142 // check the stealable queue and the overflow stack
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143 // separately.
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144 bool ChunkTaskQueueWithOverflow::retrieve(ChunkTask& chunk_task) {
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145 bool result = retrieve_from_overflow(chunk_task);
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146 if (!result) {
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147 result = retrieve_from_stealable_queue(chunk_task);
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148 }
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149 if (TraceChunkTasksQueuing && Verbose && result) {
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150 gclog_or_tty->print_cr(" CTQ: retrieve " PTR_FORMAT, result);
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151 }
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152 return result;
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153 }
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154
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155 bool ChunkTaskQueueWithOverflow::retrieve_from_stealable_queue(
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156 ChunkTask& chunk_task) {
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157 bool result = _chunk_queue.pop_local(chunk_task);
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158 if (TraceChunkTasksQueuing && Verbose) {
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159 gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
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160 }
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161 return result;
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162 }
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163
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164 bool ChunkTaskQueueWithOverflow::retrieve_from_overflow(
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165 ChunkTask& chunk_task) {
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166 bool result;
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167 if (!_overflow_stack->is_empty()) {
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168 chunk_task = _overflow_stack->pop();
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169 result = true;
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170 } else {
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171 chunk_task = (ChunkTask) NULL;
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172 result = false;
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173 }
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174 if (TraceChunkTasksQueuing && Verbose) {
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175 gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
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176 }
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177 return result;
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178 }
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