Mercurial > hg > graal-compiler
annotate src/share/vm/utilities/yieldingWorkgroup.cpp @ 1552:c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair
| author | trims |
|---|---|
| date | Thu, 27 May 2010 19:08:38 -0700 |
| parents | 37f87013dfd8 |
| children | 8b10f48633dc |
| rev | line source |
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| 0 | 1 /* |
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2 * Copyright (c) 2005, 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) : |
| 35 AbstractWorkGang(name, are_GC_task_threads, false) { | |
| 0 | 36 // Save arguments. |
| 37 _total_workers = workers; | |
| 38 assert(_total_workers > 0, "Must have more than 1 worker"); | |
| 39 | |
| 40 _yielded_workers = 0; | |
| 41 | |
| 42 if (TraceWorkGang) { | |
| 43 tty->print_cr("Constructing work gang %s with %d threads", name, workers); | |
| 44 } | |
| 45 _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, workers); | |
| 46 assert(gang_workers() != NULL, "Failed to allocate gang workers"); | |
| 47 for (int worker = 0; worker < total_workers(); worker += 1) { | |
| 48 YieldingFlexibleGangWorker* new_worker = | |
| 49 new YieldingFlexibleGangWorker(this, worker); | |
| 50 assert(new_worker != NULL, "Failed to allocate YieldingFlexibleGangWorker"); | |
| 51 _gang_workers[worker] = new_worker; | |
| 52 if (new_worker == NULL || !os::create_thread(new_worker, os::pgc_thread)) | |
| 53 vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources."); | |
| 54 if (!DisableStartThread) { | |
| 55 os::start_thread(new_worker); | |
| 56 } | |
| 57 } | |
| 58 } | |
| 59 | |
| 60 // Run a task; returns when the task is done, or the workers yield, | |
| 61 // or the task is aborted, or the work gang is terminated via stop(). | |
| 62 // A task that has been yielded can be continued via this interface | |
| 63 // by using the same task repeatedly as the argument to the call. | |
| 64 // It is expected that the YieldingFlexibleGangTask carries the appropriate | |
| 65 // continuation information used by workers to continue the task | |
| 66 // from its last yield point. Thus, a completed task will return | |
| 67 // immediately with no actual work having been done by the workers. | |
| 68 ///////////////////// | |
| 69 // Implementatiuon notes: remove before checking XXX | |
| 70 /* | |
| 71 Each gang is working on a task at a certain time. | |
| 72 Some subset of workers may have yielded and some may | |
| 73 have finished their quota of work. Until this task has | |
| 74 been completed, the workers are bound to that task. | |
| 75 Once the task has been completed, the gang unbounds | |
| 76 itself from the task. | |
| 77 | |
| 78 The yielding work gang thus exports two invokation | |
| 79 interfaces: run_task() and continue_task(). The | |
| 80 first is used to initiate a new task and bind it | |
| 81 to the workers; the second is used to continue an | |
| 82 already bound task that has yielded. Upon completion | |
| 83 the binding is released and a new binding may be | |
| 84 created. | |
| 85 | |
| 86 The shape of a yielding work gang is as follows: | |
| 87 | |
| 88 Overseer invokes run_task(*task). | |
| 89 Lock gang monitor | |
| 90 Check that there is no existing binding for the gang | |
| 91 If so, abort with an error | |
| 92 Else, create a new binding of this gang to the given task | |
| 93 Set number of active workers (as asked) | |
| 94 Notify workers that work is ready to be done | |
| 95 [the requisite # workers would then start up | |
| 96 and do the task] | |
| 97 Wait on the monitor until either | |
| 98 all work is completed or the task has yielded | |
| 99 -- this is normally done through | |
| 100 yielded + completed == active | |
| 101 [completed workers are rest to idle state by overseer?] | |
| 102 return appropriate status to caller | |
| 103 | |
| 104 Overseer invokes continue_task(*task), | |
| 105 Lock gang monitor | |
| 106 Check that task is the same as current binding | |
| 107 If not, abort with an error | |
| 108 Else, set the number of active workers as requested? | |
| 109 Notify workers that they can continue from yield points | |
| 110 New workers can also start up as required | |
| 111 while satisfying the constraint that | |
| 112 active + yielded does not exceed required number | |
| 113 Wait (as above). | |
| 114 | |
| 115 NOTE: In the above, for simplicity in a first iteration | |
| 116 our gangs will be of fixed population and will not | |
| 117 therefore be flexible work gangs, just yielding work | |
| 118 gangs. Once this works well, we will in a second | |
| 119 iteration.refinement introduce flexibility into | |
| 120 the work gang. | |
| 121 | |
| 122 NOTE: we can always create a new gang per each iteration | |
| 123 in order to get the flexibility, but we will for now | |
| 124 desist that simplified route. | |
| 125 | |
| 126 */ | |
| 127 ///////////////////// | |
| 128 void YieldingFlexibleWorkGang::start_task(YieldingFlexibleGangTask* new_task) { | |
| 129 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 130 assert(task() == NULL, "Gang currently tied to a task"); | |
| 131 assert(new_task != NULL, "Null task"); | |
| 132 // Bind task to gang | |
| 133 _task = new_task; | |
| 134 new_task->set_gang(this); // Establish 2-way binding to support yielding | |
| 135 _sequence_number++; | |
| 136 | |
| 137 int requested_size = new_task->requested_size(); | |
| 138 assert(requested_size >= 0, "Should be non-negative"); | |
| 139 if (requested_size != 0) { | |
| 140 _active_workers = MIN2(requested_size, total_workers()); | |
| 141 } else { | |
| 142 _active_workers = total_workers(); | |
| 143 } | |
| 144 new_task->set_actual_size(_active_workers); | |
| 145 | |
| 146 assert(_started_workers == 0, "Tabula rasa non"); | |
| 147 assert(_finished_workers == 0, "Tabula rasa non"); | |
| 148 assert(_yielded_workers == 0, "Tabula rasa non"); | |
| 149 yielding_task()->set_status(ACTIVE); | |
| 150 | |
| 151 // Wake up all the workers, the first few will get to work, | |
| 152 // and the rest will go back to sleep | |
| 153 monitor()->notify_all(); | |
| 154 wait_for_gang(); | |
| 155 } | |
| 156 | |
| 157 void YieldingFlexibleWorkGang::wait_for_gang() { | |
| 158 | |
| 159 assert(monitor()->owned_by_self(), "Data race"); | |
| 160 // Wait for task to complete or yield | |
| 161 for (Status status = yielding_task()->status(); | |
| 162 status != COMPLETED && status != YIELDED && status != ABORTED; | |
| 163 status = yielding_task()->status()) { | |
| 164 assert(started_workers() <= active_workers(), "invariant"); | |
| 165 assert(finished_workers() <= active_workers(), "invariant"); | |
| 166 assert(yielded_workers() <= active_workers(), "invariant"); | |
| 167 monitor()->wait(Mutex::_no_safepoint_check_flag); | |
| 168 } | |
| 169 switch (yielding_task()->status()) { | |
| 170 case COMPLETED: | |
| 171 case ABORTED: { | |
| 172 assert(finished_workers() == active_workers(), "Inconsistent status"); | |
| 173 assert(yielded_workers() == 0, "Invariant"); | |
| 174 reset(); // for next task; gang<->task binding released | |
| 175 break; | |
| 176 } | |
| 177 case YIELDED: { | |
| 178 assert(yielded_workers() > 0, "Invariant"); | |
| 179 assert(yielded_workers() + finished_workers() == active_workers(), | |
| 180 "Inconsistent counts"); | |
| 181 break; | |
| 182 } | |
| 183 case ACTIVE: | |
| 184 case INACTIVE: | |
| 185 case COMPLETING: | |
| 186 case YIELDING: | |
| 187 case ABORTING: | |
| 188 default: | |
| 189 ShouldNotReachHere(); | |
| 190 } | |
| 191 } | |
| 192 | |
| 193 void YieldingFlexibleWorkGang::continue_task( | |
| 194 YieldingFlexibleGangTask* gang_task) { | |
| 195 | |
| 196 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 197 assert(task() != NULL && task() == gang_task, "Incorrect usage"); | |
| 198 // assert(_active_workers == total_workers(), "For now"); | |
| 199 assert(_started_workers == _active_workers, "Precondition"); | |
| 200 assert(_yielded_workers > 0 && yielding_task()->status() == YIELDED, | |
| 201 "Else why are we calling continue_task()"); | |
| 202 // Restart the yielded gang workers | |
| 203 yielding_task()->set_status(ACTIVE); | |
| 204 monitor()->notify_all(); | |
| 205 wait_for_gang(); | |
| 206 } | |
| 207 | |
| 208 void YieldingFlexibleWorkGang::reset() { | |
| 209 _started_workers = 0; | |
| 210 _finished_workers = 0; | |
| 211 _active_workers = 0; | |
| 212 yielding_task()->set_gang(NULL); | |
| 213 _task = NULL; // unbind gang from task | |
| 214 } | |
| 215 | |
| 216 void YieldingFlexibleWorkGang::yield() { | |
| 217 assert(task() != NULL, "Inconsistency; should have task binding"); | |
| 218 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 219 assert(yielded_workers() < active_workers(), "Consistency check"); | |
| 220 if (yielding_task()->status() == ABORTING) { | |
| 221 // Do not yield; we need to abort as soon as possible | |
| 222 // XXX NOTE: This can cause a performance pathology in the | |
| 223 // current implementation in Mustang, as of today, and | |
| 224 // pre-Mustang in that as soon as an overflow occurs, | |
| 225 // yields will not be honoured. The right way to proceed | |
| 226 // of course is to fix bug # TBF, so that abort's cause | |
| 227 // us to return at each potential yield point. | |
| 228 return; | |
| 229 } | |
| 230 if (++_yielded_workers + finished_workers() == active_workers()) { | |
| 231 yielding_task()->set_status(YIELDED); | |
| 232 monitor()->notify_all(); | |
| 233 } else { | |
| 234 yielding_task()->set_status(YIELDING); | |
| 235 } | |
| 236 | |
| 237 while (true) { | |
| 238 switch (yielding_task()->status()) { | |
| 239 case YIELDING: | |
| 240 case YIELDED: { | |
| 241 monitor()->wait(Mutex::_no_safepoint_check_flag); | |
| 242 break; // from switch | |
| 243 } | |
| 244 case ACTIVE: | |
| 245 case ABORTING: | |
| 246 case COMPLETING: { | |
| 247 assert(_yielded_workers > 0, "Else why am i here?"); | |
| 248 _yielded_workers--; | |
| 249 return; | |
| 250 } | |
| 251 case INACTIVE: | |
| 252 case ABORTED: | |
| 253 case COMPLETED: | |
| 254 default: { | |
| 255 ShouldNotReachHere(); | |
| 256 } | |
| 257 } | |
| 258 } | |
| 259 // Only return is from inside switch statement above | |
| 260 ShouldNotReachHere(); | |
| 261 } | |
| 262 | |
| 263 void YieldingFlexibleWorkGang::abort() { | |
| 264 assert(task() != NULL, "Inconsistency; should have task binding"); | |
| 265 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); | |
| 266 assert(yielded_workers() < active_workers(), "Consistency check"); | |
| 267 #ifndef PRODUCT | |
| 268 switch (yielding_task()->status()) { | |
| 269 // allowed states | |
| 270 case ACTIVE: | |
| 271 case ABORTING: | |
| 272 case COMPLETING: | |
| 273 case YIELDING: | |
| 274 break; | |
| 275 // not allowed states | |
| 276 case INACTIVE: | |
| 277 case ABORTED: | |
| 278 case COMPLETED: | |
| 279 case YIELDED: | |
| 280 default: | |
| 281 ShouldNotReachHere(); | |
| 282 } | |
| 283 #endif // !PRODUCT | |
| 284 Status prev_status = yielding_task()->status(); | |
| 285 yielding_task()->set_status(ABORTING); | |
| 286 if (prev_status == YIELDING) { | |
| 287 assert(yielded_workers() > 0, "Inconsistency"); | |
| 288 // At least one thread has yielded, wake it up | |
| 289 // so it can go back to waiting stations ASAP. | |
| 290 monitor()->notify_all(); | |
| 291 } | |
| 292 } | |
| 293 | |
| 294 /////////////////////////////// | |
| 295 // YieldingFlexibleGangTask | |
| 296 /////////////////////////////// | |
| 297 void YieldingFlexibleGangTask::yield() { | |
| 298 assert(gang() != NULL, "No gang to signal"); | |
| 299 gang()->yield(); | |
| 300 } | |
| 301 | |
| 302 void YieldingFlexibleGangTask::abort() { | |
| 303 assert(gang() != NULL, "No gang to signal"); | |
| 304 gang()->abort(); | |
| 305 } | |
| 306 | |
| 307 /////////////////////////////// | |
| 308 // YieldingFlexibleGangWorker | |
| 309 /////////////////////////////// | |
| 310 void YieldingFlexibleGangWorker::loop() { | |
| 311 int previous_sequence_number = 0; | |
| 312 Monitor* gang_monitor = gang()->monitor(); | |
| 313 MutexLockerEx ml(gang_monitor, Mutex::_no_safepoint_check_flag); | |
| 314 WorkData data; | |
| 315 int id; | |
| 316 while (true) { | |
| 317 // Check if there is work to do or if we have been asked | |
| 318 // to terminate | |
| 319 gang()->internal_worker_poll(&data); | |
| 320 if (data.terminate()) { | |
| 321 // We have been asked to terminate. | |
| 322 assert(gang()->task() == NULL, "No task binding"); | |
| 323 // set_status(TERMINATED); | |
| 324 return; | |
| 325 } else if (data.task() != NULL && | |
| 326 data.sequence_number() != previous_sequence_number) { | |
| 327 // There is work to be done. | |
| 328 // First check if we need to become active or if there | |
| 329 // are already the requisite number of workers | |
| 330 if (gang()->started_workers() == yf_gang()->active_workers()) { | |
| 331 // There are already enough workers, we do not need to | |
| 332 // to run; fall through and wait on monitor. | |
| 333 } else { | |
| 334 // We need to pitch in and do the work. | |
| 335 assert(gang()->started_workers() < yf_gang()->active_workers(), | |
| 336 "Unexpected state"); | |
| 337 id = gang()->started_workers(); | |
| 338 gang()->internal_note_start(); | |
| 339 // Now, release the gang mutex and do the work. | |
| 340 { | |
| 341 MutexUnlockerEx mul(gang_monitor, Mutex::_no_safepoint_check_flag); | |
| 342 data.task()->work(id); // This might include yielding | |
| 343 } | |
| 344 // Reacquire monitor and note completion of this worker | |
| 345 gang()->internal_note_finish(); | |
| 346 // Update status of task based on whether all workers have | |
| 347 // finished or some have yielded | |
| 348 assert(data.task() == gang()->task(), "Confused task binding"); | |
| 349 if (gang()->finished_workers() == yf_gang()->active_workers()) { | |
| 350 switch (data.yf_task()->status()) { | |
| 351 case ABORTING: { | |
| 352 data.yf_task()->set_status(ABORTED); | |
| 353 break; | |
| 354 } | |
| 355 case ACTIVE: | |
| 356 case COMPLETING: { | |
| 357 data.yf_task()->set_status(COMPLETED); | |
| 358 break; | |
| 359 } | |
| 360 default: | |
| 361 ShouldNotReachHere(); | |
| 362 } | |
| 363 gang_monitor->notify_all(); // Notify overseer | |
| 364 } else { // at least one worker is still working or yielded | |
| 365 assert(gang()->finished_workers() < yf_gang()->active_workers(), | |
| 366 "Counts inconsistent"); | |
| 367 switch (data.yf_task()->status()) { | |
| 368 case ACTIVE: { | |
| 369 // first, but not only thread to complete | |
| 370 data.yf_task()->set_status(COMPLETING); | |
| 371 break; | |
| 372 } | |
| 373 case YIELDING: { | |
| 374 if (gang()->finished_workers() + yf_gang()->yielded_workers() | |
| 375 == yf_gang()->active_workers()) { | |
| 376 data.yf_task()->set_status(YIELDED); | |
| 377 gang_monitor->notify_all(); // notify overseer | |
| 378 } | |
| 379 break; | |
| 380 } | |
| 381 case ABORTING: | |
| 382 case COMPLETING: { | |
| 383 break; // nothing to do | |
| 384 } | |
| 385 default: // everything else: INACTIVE, YIELDED, ABORTED, COMPLETED | |
| 386 ShouldNotReachHere(); | |
| 387 } | |
| 388 } | |
| 389 } | |
| 390 } | |
| 391 // Remember the sequence number | |
| 392 previous_sequence_number = data.sequence_number(); | |
| 393 // Wait for more work | |
| 394 gang_monitor->wait(Mutex::_no_safepoint_check_flag); | |
| 395 } | |
| 396 } |