Mon, 02 Jul 2012 13:11:28 -0400
Merge
1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "oops/oop.inline.hpp"
27 #include "runtime/os.hpp"
28 #include "utilities/debug.hpp"
29 #include "utilities/stack.inline.hpp"
30 #include "utilities/taskqueue.hpp"
31 #ifdef TARGET_OS_FAMILY_linux
32 # include "thread_linux.inline.hpp"
33 #endif
34 #ifdef TARGET_OS_FAMILY_solaris
35 # include "thread_solaris.inline.hpp"
36 #endif
37 #ifdef TARGET_OS_FAMILY_windows
38 # include "thread_windows.inline.hpp"
39 #endif
40 #ifdef TARGET_OS_FAMILY_bsd
41 # include "thread_bsd.inline.hpp"
42 #endif
44 #ifdef TRACESPINNING
45 uint ParallelTaskTerminator::_total_yields = 0;
46 uint ParallelTaskTerminator::_total_spins = 0;
47 uint ParallelTaskTerminator::_total_peeks = 0;
48 #endif
50 #if TASKQUEUE_STATS
51 const char * const TaskQueueStats::_names[last_stat_id] = {
52 "qpush", "qpop", "qpop-s", "qattempt", "qsteal", "opush", "omax"
53 };
55 TaskQueueStats & TaskQueueStats::operator +=(const TaskQueueStats & addend)
56 {
57 for (unsigned int i = 0; i < last_stat_id; ++i) {
58 _stats[i] += addend._stats[i];
59 }
60 return *this;
61 }
63 void TaskQueueStats::print_header(unsigned int line, outputStream* const stream,
64 unsigned int width)
65 {
66 // Use a width w: 1 <= w <= max_width
67 const unsigned int max_width = 40;
68 const unsigned int w = MAX2(MIN2(width, max_width), 1U);
70 if (line == 0) { // spaces equal in width to the header
71 const unsigned int hdr_width = w * last_stat_id + last_stat_id - 1;
72 stream->print("%*s", hdr_width, " ");
73 } else if (line == 1) { // labels
74 stream->print("%*s", w, _names[0]);
75 for (unsigned int i = 1; i < last_stat_id; ++i) {
76 stream->print(" %*s", w, _names[i]);
77 }
78 } else if (line == 2) { // dashed lines
79 char dashes[max_width + 1];
80 memset(dashes, '-', w);
81 dashes[w] = '\0';
82 stream->print("%s", dashes);
83 for (unsigned int i = 1; i < last_stat_id; ++i) {
84 stream->print(" %s", dashes);
85 }
86 }
87 }
89 void TaskQueueStats::print(outputStream* stream, unsigned int width) const
90 {
91 #define FMT SIZE_FORMAT_W(*)
92 stream->print(FMT, width, _stats[0]);
93 for (unsigned int i = 1; i < last_stat_id; ++i) {
94 stream->print(" " FMT, width, _stats[i]);
95 }
96 #undef FMT
97 }
99 #ifdef ASSERT
100 // Invariants which should hold after a TaskQueue has been emptied and is
101 // quiescent; they do not hold at arbitrary times.
102 void TaskQueueStats::verify() const
103 {
104 assert(get(push) == get(pop) + get(steal),
105 err_msg("push=" SIZE_FORMAT " pop=" SIZE_FORMAT " steal=" SIZE_FORMAT,
106 get(push), get(pop), get(steal)));
107 assert(get(pop_slow) <= get(pop),
108 err_msg("pop_slow=" SIZE_FORMAT " pop=" SIZE_FORMAT,
109 get(pop_slow), get(pop)));
110 assert(get(steal) <= get(steal_attempt),
111 err_msg("steal=" SIZE_FORMAT " steal_attempt=" SIZE_FORMAT,
112 get(steal), get(steal_attempt)));
113 assert(get(overflow) == 0 || get(push) != 0,
114 err_msg("overflow=" SIZE_FORMAT " push=" SIZE_FORMAT,
115 get(overflow), get(push)));
116 assert(get(overflow_max_len) == 0 || get(overflow) != 0,
117 err_msg("overflow_max_len=" SIZE_FORMAT " overflow=" SIZE_FORMAT,
118 get(overflow_max_len), get(overflow)));
119 }
120 #endif // ASSERT
121 #endif // TASKQUEUE_STATS
123 int TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
124 const int a = 16807;
125 const int m = 2147483647;
126 const int q = 127773; /* m div a */
127 const int r = 2836; /* m mod a */
128 assert(sizeof(int) == 4, "I think this relies on that");
129 int seed = *seed0;
130 int hi = seed / q;
131 int lo = seed % q;
132 int test = a * lo - r * hi;
133 if (test > 0)
134 seed = test;
135 else
136 seed = test + m;
137 *seed0 = seed;
138 return seed;
139 }
141 ParallelTaskTerminator::
142 ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
143 _n_threads(n_threads),
144 _queue_set(queue_set),
145 _offered_termination(0) {}
147 bool ParallelTaskTerminator::peek_in_queue_set() {
148 return _queue_set->peek();
149 }
151 void ParallelTaskTerminator::yield() {
152 assert(_offered_termination <= _n_threads, "Invariant");
153 os::yield();
154 }
156 void ParallelTaskTerminator::sleep(uint millis) {
157 assert(_offered_termination <= _n_threads, "Invariant");
158 os::sleep(Thread::current(), millis, false);
159 }
161 bool
162 ParallelTaskTerminator::offer_termination(TerminatorTerminator* terminator) {
163 assert(_n_threads > 0, "Initialization is incorrect");
164 assert(_offered_termination < _n_threads, "Invariant");
165 Atomic::inc(&_offered_termination);
167 uint yield_count = 0;
168 // Number of hard spin loops done since last yield
169 uint hard_spin_count = 0;
170 // Number of iterations in the hard spin loop.
171 uint hard_spin_limit = WorkStealingHardSpins;
173 // If WorkStealingSpinToYieldRatio is 0, no hard spinning is done.
174 // If it is greater than 0, then start with a small number
175 // of spins and increase number with each turn at spinning until
176 // the count of hard spins exceeds WorkStealingSpinToYieldRatio.
177 // Then do a yield() call and start spinning afresh.
178 if (WorkStealingSpinToYieldRatio > 0) {
179 hard_spin_limit = WorkStealingHardSpins >> WorkStealingSpinToYieldRatio;
180 hard_spin_limit = MAX2(hard_spin_limit, 1U);
181 }
182 // Remember the initial spin limit.
183 uint hard_spin_start = hard_spin_limit;
185 // Loop waiting for all threads to offer termination or
186 // more work.
187 while (true) {
188 assert(_offered_termination <= _n_threads, "Invariant");
189 // Are all threads offering termination?
190 if (_offered_termination == _n_threads) {
191 return true;
192 } else {
193 // Look for more work.
194 // Periodically sleep() instead of yield() to give threads
195 // waiting on the cores the chance to grab this code
196 if (yield_count <= WorkStealingYieldsBeforeSleep) {
197 // Do a yield or hardspin. For purposes of deciding whether
198 // to sleep, count this as a yield.
199 yield_count++;
201 // Periodically call yield() instead spinning
202 // After WorkStealingSpinToYieldRatio spins, do a yield() call
203 // and reset the counts and starting limit.
204 if (hard_spin_count > WorkStealingSpinToYieldRatio) {
205 yield();
206 hard_spin_count = 0;
207 hard_spin_limit = hard_spin_start;
208 #ifdef TRACESPINNING
209 _total_yields++;
210 #endif
211 } else {
212 // Hard spin this time
213 // Increase the hard spinning period but only up to a limit.
214 hard_spin_limit = MIN2(2*hard_spin_limit,
215 (uint) WorkStealingHardSpins);
216 for (uint j = 0; j < hard_spin_limit; j++) {
217 SpinPause();
218 }
219 hard_spin_count++;
220 #ifdef TRACESPINNING
221 _total_spins++;
222 #endif
223 }
224 } else {
225 if (PrintGCDetails && Verbose) {
226 gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
227 "thread %d sleeps after %d yields",
228 Thread::current(), yield_count);
229 }
230 yield_count = 0;
231 // A sleep will cause this processor to seek work on another processor's
232 // runqueue, if it has nothing else to run (as opposed to the yield
233 // which may only move the thread to the end of the this processor's
234 // runqueue).
235 sleep(WorkStealingSleepMillis);
236 }
238 #ifdef TRACESPINNING
239 _total_peeks++;
240 #endif
241 if (peek_in_queue_set() ||
242 (terminator != NULL && terminator->should_exit_termination())) {
243 Atomic::dec(&_offered_termination);
244 assert(_offered_termination < _n_threads, "Invariant");
245 return false;
246 }
247 }
248 }
249 }
251 #ifdef TRACESPINNING
252 void ParallelTaskTerminator::print_termination_counts() {
253 gclog_or_tty->print_cr("ParallelTaskTerminator Total yields: %lld "
254 "Total spins: %lld Total peeks: %lld",
255 total_yields(),
256 total_spins(),
257 total_peeks());
258 }
259 #endif
261 void ParallelTaskTerminator::reset_for_reuse() {
262 if (_offered_termination != 0) {
263 assert(_offered_termination == _n_threads,
264 "Terminator may still be in use");
265 _offered_termination = 0;
266 }
267 }
269 #ifdef ASSERT
270 bool ObjArrayTask::is_valid() const {
271 return _obj != NULL && _obj->is_objArray() && _index > 0 &&
272 _index < objArrayOop(_obj)->length();
273 }
274 #endif // ASSERT
276 void ParallelTaskTerminator::reset_for_reuse(int n_threads) {
277 reset_for_reuse();
278 _n_threads = n_threads;
279 }