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comparison src/share/vm/utilities/taskqueue.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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children 37f87013dfd8
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_taskqueue.cpp.incl"
27
28 bool TaskQueueSuper::peek() {
29 return _bottom != _age.top();
30 }
31
32 int TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
33 const int a = 16807;
34 const int m = 2147483647;
35 const int q = 127773; /* m div a */
36 const int r = 2836; /* m mod a */
37 assert(sizeof(int) == 4, "I think this relies on that");
38 int seed = *seed0;
39 int hi = seed / q;
40 int lo = seed % q;
41 int test = a * lo - r * hi;
42 if (test > 0)
43 seed = test;
44 else
45 seed = test + m;
46 *seed0 = seed;
47 return seed;
48 }
49
50 ParallelTaskTerminator::
51 ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
52 _n_threads(n_threads),
53 _queue_set(queue_set),
54 _offered_termination(0) {}
55
56 bool ParallelTaskTerminator::peek_in_queue_set() {
57 return _queue_set->peek();
58 }
59
60 void ParallelTaskTerminator::yield() {
61 os::yield();
62 }
63
64 void ParallelTaskTerminator::sleep(uint millis) {
65 os::sleep(Thread::current(), millis, false);
66 }
67
68 bool ParallelTaskTerminator::offer_termination() {
69 Atomic::inc(&_offered_termination);
70
71 juint yield_count = 0;
72 while (true) {
73 if (_offered_termination == _n_threads) {
74 //inner_termination_loop();
75 return true;
76 } else {
77 if (yield_count <= WorkStealingYieldsBeforeSleep) {
78 yield_count++;
79 yield();
80 } else {
81 if (PrintGCDetails && Verbose) {
82 gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
83 "thread %d sleeps after %d yields",
84 Thread::current(), yield_count);
85 }
86 yield_count = 0;
87 // A sleep will cause this processor to seek work on another processor's
88 // runqueue, if it has nothing else to run (as opposed to the yield
89 // which may only move the thread to the end of the this processor's
90 // runqueue).
91 sleep(WorkStealingSleepMillis);
92 }
93
94 if (peek_in_queue_set()) {
95 Atomic::dec(&_offered_termination);
96 return false;
97 }
98 }
99 }
100 }
101
102 void ParallelTaskTerminator::reset_for_reuse() {
103 if (_offered_termination != 0) {
104 assert(_offered_termination == _n_threads,
105 "Terminator may still be in use");
106 _offered_termination = 0;
107 }
108 }
109
110 bool ChunkTaskQueueWithOverflow::is_empty() {
111 return (_chunk_queue.size() == 0) &&
112 (_overflow_stack->length() == 0);
113 }
114
115 bool ChunkTaskQueueWithOverflow::stealable_is_empty() {
116 return _chunk_queue.size() == 0;
117 }
118
119 bool ChunkTaskQueueWithOverflow::overflow_is_empty() {
120 return _overflow_stack->length() == 0;
121 }
122
123 void ChunkTaskQueueWithOverflow::initialize() {
124 _chunk_queue.initialize();
125 assert(_overflow_stack == 0, "Creating memory leak");
126 _overflow_stack =
127 new (ResourceObj::C_HEAP) GrowableArray<ChunkTask>(10, true);
128 }
129
130 void ChunkTaskQueueWithOverflow::save(ChunkTask t) {
131 if (TraceChunkTasksQueuing && Verbose) {
132 gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
133 }
134 if(!_chunk_queue.push(t)) {
135 _overflow_stack->push(t);
136 }
137 }
138
139 // Note that using this method will retrieve all chunks
140 // that have been saved but that it will always check
141 // the overflow stack. It may be more efficient to
142 // check the stealable queue and the overflow stack
143 // separately.
144 bool ChunkTaskQueueWithOverflow::retrieve(ChunkTask& chunk_task) {
145 bool result = retrieve_from_overflow(chunk_task);
146 if (!result) {
147 result = retrieve_from_stealable_queue(chunk_task);
148 }
149 if (TraceChunkTasksQueuing && Verbose && result) {
150 gclog_or_tty->print_cr(" CTQ: retrieve " PTR_FORMAT, result);
151 }
152 return result;
153 }
154
155 bool ChunkTaskQueueWithOverflow::retrieve_from_stealable_queue(
156 ChunkTask& chunk_task) {
157 bool result = _chunk_queue.pop_local(chunk_task);
158 if (TraceChunkTasksQueuing && Verbose) {
159 gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
160 }
161 return result;
162 }
163
164 bool ChunkTaskQueueWithOverflow::retrieve_from_overflow(
165 ChunkTask& chunk_task) {
166 bool result;
167 if (!_overflow_stack->is_empty()) {
168 chunk_task = _overflow_stack->pop();
169 result = true;
170 } else {
171 chunk_task = (ChunkTask) NULL;
172 result = false;
173 }
174 if (TraceChunkTasksQueuing && Verbose) {
175 gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
176 }
177 return result;
178 }