Mercurial > hg > graal-compiler
annotate src/share/vm/utilities/yieldingWorkgroup.cpp @ 1833:8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
Summary: Associate number of GC workers with the workgang as opposed to the task.
Reviewed-by: johnc, ysr
| author | jmasa |
|---|---|
| date | Mon, 20 Sep 2010 14:38:38 -0700 |
| parents | c18cbe5936b8 |
| children | f95d63e2154a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2005, 2010 Oracle and/or its affiliates. All rights reserved. |
| 0 | 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 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 # include "incls/_precompiled.incl" | |
| 26 # include "incls/_yieldingWorkgroup.cpp.incl" | |
| 27 | |
| 28 // Forward declaration of classes declared here. | |
| 29 | |
| 30 class GangWorker; | |
| 31 class WorkData; | |
| 32 | |
| 33 YieldingFlexibleWorkGang::YieldingFlexibleWorkGang( | |
| 342 | 34 const char* name, int workers, bool are_GC_task_threads) : |
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35 FlexibleWorkGang(name, workers, are_GC_task_threads, false), |
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36 _yielded_workers(0) {} |
| 0 | 37 |
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38 GangWorker* YieldingFlexibleWorkGang::allocate_worker(int which) { |
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39 YieldingFlexibleGangWorker* new_member = |
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40 new YieldingFlexibleGangWorker(this, which); |
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41 return (YieldingFlexibleGangWorker*) new_member; |
| 0 | 42 } |
| 43 | |
| 44 // Run a task; returns when the task is done, or the workers yield, | |
| 45 // or the task is aborted, or the work gang is terminated via stop(). | |
| 46 // A task that has been yielded can be continued via this interface | |
| 47 // by using the same task repeatedly as the argument to the call. | |
| 48 // It is expected that the YieldingFlexibleGangTask carries the appropriate | |
| 49 // continuation information used by workers to continue the task | |
| 50 // from its last yield point. Thus, a completed task will return | |
| 51 // immediately with no actual work having been done by the workers. | |
| 52 ///////////////////// | |
| 53 // Implementatiuon notes: remove before checking XXX | |
| 54 /* | |
| 55 Each gang is working on a task at a certain time. | |
| 56 Some subset of workers may have yielded and some may | |
| 57 have finished their quota of work. Until this task has | |
| 58 been completed, the workers are bound to that task. | |
| 59 Once the task has been completed, the gang unbounds | |
| 60 itself from the task. | |
| 61 | |
| 62 The yielding work gang thus exports two invokation | |
| 63 interfaces: run_task() and continue_task(). The | |
| 64 first is used to initiate a new task and bind it | |
| 65 to the workers; the second is used to continue an | |
| 66 already bound task that has yielded. Upon completion | |
| 67 the binding is released and a new binding may be | |
| 68 created. | |
| 69 | |
| 70 The shape of a yielding work gang is as follows: | |
| 71 | |
| 72 Overseer invokes run_task(*task). | |
| 73 Lock gang monitor | |
| 74 Check that there is no existing binding for the gang | |
| 75 If so, abort with an error | |
| 76 Else, create a new binding of this gang to the given task | |
| 77 Set number of active workers (as asked) | |
| 78 Notify workers that work is ready to be done | |
| 79 [the requisite # workers would then start up | |
| 80 and do the task] | |
| 81 Wait on the monitor until either | |
| 82 all work is completed or the task has yielded | |
| 83 -- this is normally done through | |
| 84 yielded + completed == active | |
| 85 [completed workers are rest to idle state by overseer?] | |
| 86 return appropriate status to caller | |
| 87 | |
| 88 Overseer invokes continue_task(*task), | |
| 89 Lock gang monitor | |
| 90 Check that task is the same as current binding | |
| 91 If not, abort with an error | |
| 92 Else, set the number of active workers as requested? | |
| 93 Notify workers that they can continue from yield points | |
| 94 New workers can also start up as required | |
| 95 while satisfying the constraint that | |
| 96 active + yielded does not exceed required number | |
| 97 Wait (as above). | |
| 98 | |
| 99 NOTE: In the above, for simplicity in a first iteration | |
| 100 our gangs will be of fixed population and will not | |
| 101 therefore be flexible work gangs, just yielding work | |
| 102 gangs. Once this works well, we will in a second | |
| 103 iteration.refinement introduce flexibility into | |
| 104 the work gang. | |
| 105 | |
| 106 NOTE: we can always create a new gang per each iteration | |
| 107 in order to get the flexibility, but we will for now | |
| 108 desist that simplified route. | |
| 109 | |
| 110 */ | |
| 111 ///////////////////// | |
| 112 void YieldingFlexibleWorkGang::start_task(YieldingFlexibleGangTask* new_task) { | |
| 113 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 114 assert(task() == NULL, "Gang currently tied to a task"); | |
| 115 assert(new_task != NULL, "Null task"); | |
| 116 // Bind task to gang | |
| 117 _task = new_task; | |
| 118 new_task->set_gang(this); // Establish 2-way binding to support yielding | |
| 119 _sequence_number++; | |
| 120 | |
| 121 int requested_size = new_task->requested_size(); | |
| 122 assert(requested_size >= 0, "Should be non-negative"); | |
| 123 if (requested_size != 0) { | |
| 124 _active_workers = MIN2(requested_size, total_workers()); | |
| 125 } else { | |
| 126 _active_workers = total_workers(); | |
| 127 } | |
| 128 new_task->set_actual_size(_active_workers); | |
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129 new_task->set_for_termination(_active_workers); |
| 0 | 130 |
| 131 assert(_started_workers == 0, "Tabula rasa non"); | |
| 132 assert(_finished_workers == 0, "Tabula rasa non"); | |
| 133 assert(_yielded_workers == 0, "Tabula rasa non"); | |
| 134 yielding_task()->set_status(ACTIVE); | |
| 135 | |
| 136 // Wake up all the workers, the first few will get to work, | |
| 137 // and the rest will go back to sleep | |
| 138 monitor()->notify_all(); | |
| 139 wait_for_gang(); | |
| 140 } | |
| 141 | |
| 142 void YieldingFlexibleWorkGang::wait_for_gang() { | |
| 143 | |
| 144 assert(monitor()->owned_by_self(), "Data race"); | |
| 145 // Wait for task to complete or yield | |
| 146 for (Status status = yielding_task()->status(); | |
| 147 status != COMPLETED && status != YIELDED && status != ABORTED; | |
| 148 status = yielding_task()->status()) { | |
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149 assert(started_workers() <= total_workers(), "invariant"); |
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150 assert(finished_workers() <= total_workers(), "invariant"); |
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151 assert(yielded_workers() <= total_workers(), "invariant"); |
| 0 | 152 monitor()->wait(Mutex::_no_safepoint_check_flag); |
| 153 } | |
| 154 switch (yielding_task()->status()) { | |
| 155 case COMPLETED: | |
| 156 case ABORTED: { | |
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157 assert(finished_workers() == total_workers(), "Inconsistent status"); |
| 0 | 158 assert(yielded_workers() == 0, "Invariant"); |
| 159 reset(); // for next task; gang<->task binding released | |
| 160 break; | |
| 161 } | |
| 162 case YIELDED: { | |
| 163 assert(yielded_workers() > 0, "Invariant"); | |
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164 assert(yielded_workers() + finished_workers() == total_workers(), |
| 0 | 165 "Inconsistent counts"); |
| 166 break; | |
| 167 } | |
| 168 case ACTIVE: | |
| 169 case INACTIVE: | |
| 170 case COMPLETING: | |
| 171 case YIELDING: | |
| 172 case ABORTING: | |
| 173 default: | |
| 174 ShouldNotReachHere(); | |
| 175 } | |
| 176 } | |
| 177 | |
| 178 void YieldingFlexibleWorkGang::continue_task( | |
| 179 YieldingFlexibleGangTask* gang_task) { | |
| 180 | |
| 181 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 182 assert(task() != NULL && task() == gang_task, "Incorrect usage"); | |
| 183 // assert(_active_workers == total_workers(), "For now"); | |
| 184 assert(_started_workers == _active_workers, "Precondition"); | |
| 185 assert(_yielded_workers > 0 && yielding_task()->status() == YIELDED, | |
| 186 "Else why are we calling continue_task()"); | |
| 187 // Restart the yielded gang workers | |
| 188 yielding_task()->set_status(ACTIVE); | |
| 189 monitor()->notify_all(); | |
| 190 wait_for_gang(); | |
| 191 } | |
| 192 | |
| 193 void YieldingFlexibleWorkGang::reset() { | |
| 194 _started_workers = 0; | |
| 195 _finished_workers = 0; | |
| 196 yielding_task()->set_gang(NULL); | |
| 197 _task = NULL; // unbind gang from task | |
| 198 } | |
| 199 | |
| 200 void YieldingFlexibleWorkGang::yield() { | |
| 201 assert(task() != NULL, "Inconsistency; should have task binding"); | |
| 202 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
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203 assert(yielded_workers() < total_workers(), "Consistency check"); |
| 0 | 204 if (yielding_task()->status() == ABORTING) { |
| 205 // Do not yield; we need to abort as soon as possible | |
| 206 // XXX NOTE: This can cause a performance pathology in the | |
| 207 // current implementation in Mustang, as of today, and | |
| 208 // pre-Mustang in that as soon as an overflow occurs, | |
| 209 // yields will not be honoured. The right way to proceed | |
| 210 // of course is to fix bug # TBF, so that abort's cause | |
| 211 // us to return at each potential yield point. | |
| 212 return; | |
| 213 } | |
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214 if (++_yielded_workers + finished_workers() == total_workers()) { |
| 0 | 215 yielding_task()->set_status(YIELDED); |
| 216 monitor()->notify_all(); | |
| 217 } else { | |
| 218 yielding_task()->set_status(YIELDING); | |
| 219 } | |
| 220 | |
| 221 while (true) { | |
| 222 switch (yielding_task()->status()) { | |
| 223 case YIELDING: | |
| 224 case YIELDED: { | |
| 225 monitor()->wait(Mutex::_no_safepoint_check_flag); | |
| 226 break; // from switch | |
| 227 } | |
| 228 case ACTIVE: | |
| 229 case ABORTING: | |
| 230 case COMPLETING: { | |
| 231 assert(_yielded_workers > 0, "Else why am i here?"); | |
| 232 _yielded_workers--; | |
| 233 return; | |
| 234 } | |
| 235 case INACTIVE: | |
| 236 case ABORTED: | |
| 237 case COMPLETED: | |
| 238 default: { | |
| 239 ShouldNotReachHere(); | |
| 240 } | |
| 241 } | |
| 242 } | |
| 243 // Only return is from inside switch statement above | |
| 244 ShouldNotReachHere(); | |
| 245 } | |
| 246 | |
| 247 void YieldingFlexibleWorkGang::abort() { | |
| 248 assert(task() != NULL, "Inconsistency; should have task binding"); | |
| 249 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 250 assert(yielded_workers() < active_workers(), "Consistency check"); | |
| 251 #ifndef PRODUCT | |
| 252 switch (yielding_task()->status()) { | |
| 253 // allowed states | |
| 254 case ACTIVE: | |
| 255 case ABORTING: | |
| 256 case COMPLETING: | |
| 257 case YIELDING: | |
| 258 break; | |
| 259 // not allowed states | |
| 260 case INACTIVE: | |
| 261 case ABORTED: | |
| 262 case COMPLETED: | |
| 263 case YIELDED: | |
| 264 default: | |
| 265 ShouldNotReachHere(); | |
| 266 } | |
| 267 #endif // !PRODUCT | |
| 268 Status prev_status = yielding_task()->status(); | |
| 269 yielding_task()->set_status(ABORTING); | |
| 270 if (prev_status == YIELDING) { | |
| 271 assert(yielded_workers() > 0, "Inconsistency"); | |
| 272 // At least one thread has yielded, wake it up | |
| 273 // so it can go back to waiting stations ASAP. | |
| 274 monitor()->notify_all(); | |
| 275 } | |
| 276 } | |
| 277 | |
| 278 /////////////////////////////// | |
| 279 // YieldingFlexibleGangTask | |
| 280 /////////////////////////////// | |
| 281 void YieldingFlexibleGangTask::yield() { | |
| 282 assert(gang() != NULL, "No gang to signal"); | |
| 283 gang()->yield(); | |
| 284 } | |
| 285 | |
| 286 void YieldingFlexibleGangTask::abort() { | |
| 287 assert(gang() != NULL, "No gang to signal"); | |
| 288 gang()->abort(); | |
| 289 } | |
| 290 | |
| 291 /////////////////////////////// | |
| 292 // YieldingFlexibleGangWorker | |
| 293 /////////////////////////////// | |
| 294 void YieldingFlexibleGangWorker::loop() { | |
| 295 int previous_sequence_number = 0; | |
| 296 Monitor* gang_monitor = gang()->monitor(); | |
| 297 MutexLockerEx ml(gang_monitor, Mutex::_no_safepoint_check_flag); | |
| 298 WorkData data; | |
| 299 int id; | |
| 300 while (true) { | |
| 301 // Check if there is work to do or if we have been asked | |
| 302 // to terminate | |
| 303 gang()->internal_worker_poll(&data); | |
| 304 if (data.terminate()) { | |
| 305 // We have been asked to terminate. | |
| 306 assert(gang()->task() == NULL, "No task binding"); | |
| 307 // set_status(TERMINATED); | |
| 308 return; | |
| 309 } else if (data.task() != NULL && | |
| 310 data.sequence_number() != previous_sequence_number) { | |
| 311 // There is work to be done. | |
| 312 // First check if we need to become active or if there | |
| 313 // are already the requisite number of workers | |
| 314 if (gang()->started_workers() == yf_gang()->active_workers()) { | |
| 315 // There are already enough workers, we do not need to | |
| 316 // to run; fall through and wait on monitor. | |
| 317 } else { | |
| 318 // We need to pitch in and do the work. | |
| 319 assert(gang()->started_workers() < yf_gang()->active_workers(), | |
| 320 "Unexpected state"); | |
| 321 id = gang()->started_workers(); | |
| 322 gang()->internal_note_start(); | |
| 323 // Now, release the gang mutex and do the work. | |
| 324 { | |
| 325 MutexUnlockerEx mul(gang_monitor, Mutex::_no_safepoint_check_flag); | |
| 326 data.task()->work(id); // This might include yielding | |
| 327 } | |
| 328 // Reacquire monitor and note completion of this worker | |
| 329 gang()->internal_note_finish(); | |
| 330 // Update status of task based on whether all workers have | |
| 331 // finished or some have yielded | |
| 332 assert(data.task() == gang()->task(), "Confused task binding"); | |
| 333 if (gang()->finished_workers() == yf_gang()->active_workers()) { | |
| 334 switch (data.yf_task()->status()) { | |
| 335 case ABORTING: { | |
| 336 data.yf_task()->set_status(ABORTED); | |
| 337 break; | |
| 338 } | |
| 339 case ACTIVE: | |
| 340 case COMPLETING: { | |
| 341 data.yf_task()->set_status(COMPLETED); | |
| 342 break; | |
| 343 } | |
| 344 default: | |
| 345 ShouldNotReachHere(); | |
| 346 } | |
| 347 gang_monitor->notify_all(); // Notify overseer | |
| 348 } else { // at least one worker is still working or yielded | |
| 349 assert(gang()->finished_workers() < yf_gang()->active_workers(), | |
| 350 "Counts inconsistent"); | |
| 351 switch (data.yf_task()->status()) { | |
| 352 case ACTIVE: { | |
| 353 // first, but not only thread to complete | |
| 354 data.yf_task()->set_status(COMPLETING); | |
| 355 break; | |
| 356 } | |
| 357 case YIELDING: { | |
| 358 if (gang()->finished_workers() + yf_gang()->yielded_workers() | |
| 359 == yf_gang()->active_workers()) { | |
| 360 data.yf_task()->set_status(YIELDED); | |
| 361 gang_monitor->notify_all(); // notify overseer | |
| 362 } | |
| 363 break; | |
| 364 } | |
| 365 case ABORTING: | |
| 366 case COMPLETING: { | |
| 367 break; // nothing to do | |
| 368 } | |
| 369 default: // everything else: INACTIVE, YIELDED, ABORTED, COMPLETED | |
| 370 ShouldNotReachHere(); | |
| 371 } | |
| 372 } | |
| 373 } | |
| 374 } | |
| 375 // Remember the sequence number | |
| 376 previous_sequence_number = data.sequence_number(); | |
| 377 // Wait for more work | |
| 378 gang_monitor->wait(Mutex::_no_safepoint_check_flag); | |
| 379 } | |
| 380 } |