1 /* 2 * Copyright (c) 2002, 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 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 27 #include "gc_implementation/parallelScavenge/psOldGen.hpp" 28 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp" 29 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" 30 #include "gc_implementation/shared/mutableSpace.hpp" 31 #include "memory/memRegion.hpp" 32 #include "oops/oop.inline.hpp" 33 #include "oops/oop.psgc.inline.hpp" 34 35 PSPromotionManager** PSPromotionManager::_manager_array = NULL; 36 OopStarTaskQueueSet* PSPromotionManager::_stack_array_depth = NULL; 37 PSOldGen* PSPromotionManager::_old_gen = NULL; 38 MutableSpace* PSPromotionManager::_young_space = NULL; 39 40 void PSPromotionManager::initialize() { 41 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 42 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 43 44 _old_gen = heap->old_gen(); 45 _young_space = heap->young_gen()->to_space(); 46 47 assert(_manager_array == NULL, "Attempt to initialize twice"); 48 _manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 ); 49 guarantee(_manager_array != NULL, "Could not initialize promotion manager"); 50 51 _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads); 52 guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager"); 53 54 // Create and register the PSPromotionManager(s) for the worker threads. 55 for(uint i=0; i<ParallelGCThreads; i++) { 56 _manager_array[i] = new PSPromotionManager(); 57 guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager"); 58 stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth()); 59 } 60 61 // The VMThread gets its own PSPromotionManager, which is not available 62 // for work stealing. 63 _manager_array[ParallelGCThreads] = new PSPromotionManager(); 64 guarantee(_manager_array[ParallelGCThreads] != NULL, "Could not create PSPromotionManager"); 65 } 66 67 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) { 68 assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range"); 69 assert(_manager_array != NULL, "Sanity"); 70 return _manager_array[index]; 71 } 72 73 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() { 74 assert(_manager_array != NULL, "Sanity"); 75 return _manager_array[ParallelGCThreads]; 76 } 77 78 void PSPromotionManager::pre_scavenge() { 79 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 80 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 81 82 _young_space = heap->young_gen()->to_space(); 83 84 for(uint i=0; i<ParallelGCThreads+1; i++) { 85 manager_array(i)->reset(); 86 } 87 } 88 89 void PSPromotionManager::post_scavenge() { 90 TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats()); 91 for (uint i = 0; i < ParallelGCThreads + 1; i++) { 92 PSPromotionManager* manager = manager_array(i); 93 assert(manager->claimed_stack_depth()->is_empty(), "should be empty"); 94 manager->flush_labs(); 95 } 96 } 97 98 #if TASKQUEUE_STATS 99 void 100 PSPromotionManager::print_taskqueue_stats(uint i) const { 101 tty->print("%3u ", i); 102 _claimed_stack_depth.stats.print(); 103 tty->cr(); 104 } 105 106 void 107 PSPromotionManager::print_local_stats(uint i) const { 108 #define FMT " " SIZE_FORMAT_W(10) 109 tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals, 110 _arrays_chunked, _array_chunks_processed); 111 #undef FMT 112 } 113 114 static const char* const pm_stats_hdr[] = { 115 " --------masked------- arrays array", 116 "thr push steal chunked chunks", 117 "--- ---------- ---------- ---------- ----------" 118 }; 119 120 void 121 PSPromotionManager::print_stats() { 122 tty->print_cr("== GC Tasks Stats, GC %3d", 123 Universe::heap()->total_collections()); 124 125 tty->print("thr "); TaskQueueStats::print_header(1); tty->cr(); 126 tty->print("--- "); TaskQueueStats::print_header(2); tty->cr(); 127 for (uint i = 0; i < ParallelGCThreads + 1; ++i) { 128 manager_array(i)->print_taskqueue_stats(i); 129 } 130 131 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]); 132 for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]); 133 for (uint i = 0; i < ParallelGCThreads + 1; ++i) { 134 manager_array(i)->print_local_stats(i); 135 } 136 } 137 138 void 139 PSPromotionManager::reset_stats() { 140 claimed_stack_depth()->stats.reset(); 141 _masked_pushes = _masked_steals = 0; 142 _arrays_chunked = _array_chunks_processed = 0; 143 } 144 #endif // TASKQUEUE_STATS 145 146 PSPromotionManager::PSPromotionManager() { 147 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 148 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 149 150 // We set the old lab's start array. 151 _old_lab.set_start_array(old_gen()->start_array()); 152 153 uint queue_size; 154 claimed_stack_depth()->initialize(); 155 queue_size = claimed_stack_depth()->max_elems(); 156 157 _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0); 158 if (_totally_drain) { 159 _target_stack_size = 0; 160 } else { 161 // don't let the target stack size to be more than 1/4 of the entries 162 _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize, 163 (uint) (queue_size / 4)); 164 } 165 166 _array_chunk_size = ParGCArrayScanChunk; 167 // let's choose 1.5x the chunk size 168 _min_array_size_for_chunking = 3 * _array_chunk_size / 2; 169 170 reset(); 171 } 172 173 void PSPromotionManager::reset() { 174 assert(stacks_empty(), "reset of non-empty stack"); 175 176 // We need to get an assert in here to make sure the labs are always flushed. 177 178 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 179 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 180 181 // Do not prefill the LAB's, save heap wastage! 182 HeapWord* lab_base = young_space()->top(); 183 _young_lab.initialize(MemRegion(lab_base, (size_t)0)); 184 _young_gen_is_full = false; 185 186 lab_base = old_gen()->object_space()->top(); 187 _old_lab.initialize(MemRegion(lab_base, (size_t)0)); 188 _old_gen_is_full = false; 189 190 TASKQUEUE_STATS_ONLY(reset_stats()); 191 } 192 193 194 void PSPromotionManager::drain_stacks_depth(bool totally_drain) { 195 assert(claimed_stack_depth()->overflow_stack() != NULL, "invariant"); 196 totally_drain = totally_drain || _totally_drain; 197 198 #ifdef ASSERT 199 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 200 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 201 MutableSpace* to_space = heap->young_gen()->to_space(); 202 MutableSpace* old_space = heap->old_gen()->object_space(); 203 MutableSpace* perm_space = heap->perm_gen()->object_space(); 204 #endif /* ASSERT */ 205 206 OopStarTaskQueue* const tq = claimed_stack_depth(); 207 do { 208 StarTask p; 209 210 // Drain overflow stack first, so other threads can steal from 211 // claimed stack while we work. 212 while (tq->pop_overflow(p)) { 213 process_popped_location_depth(p); 214 } 215 216 if (totally_drain) { 217 while (tq->pop_local(p)) { 218 process_popped_location_depth(p); 219 } 220 } else { 221 while (tq->size() > _target_stack_size && tq->pop_local(p)) { 222 process_popped_location_depth(p); 223 } 224 } 225 } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty()); 226 227 assert(!totally_drain || tq->taskqueue_empty(), "Sanity"); 228 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity"); 229 assert(tq->overflow_empty(), "Sanity"); 230 } 231 232 void PSPromotionManager::flush_labs() { 233 assert(stacks_empty(), "Attempt to flush lab with live stack"); 234 235 // If either promotion lab fills up, we can flush the 236 // lab but not refill it, so check first. 237 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity"); 238 if (!_young_lab.is_flushed()) 239 _young_lab.flush(); 240 241 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity"); 242 if (!_old_lab.is_flushed()) 243 _old_lab.flush(); 244 245 // Let PSScavenge know if we overflowed 246 if (_young_gen_is_full) { 247 PSScavenge::set_survivor_overflow(true); 248 } 249 } 250 251 // 252 // This method is pretty bulky. It would be nice to split it up 253 // into smaller submethods, but we need to be careful not to hurt 254 // performance. 255 // 256 257 oop PSPromotionManager::copy_to_survivor_space(oop o) { 258 assert(PSScavenge::should_scavenge(&o), "Sanity"); 259 260 oop new_obj = NULL; 261 262 // NOTE! We must be very careful with any methods that access the mark 263 // in o. There may be multiple threads racing on it, and it may be forwarded 264 // at any time. Do not use oop methods for accessing the mark! 265 markOop test_mark = o->mark(); 266 267 // The same test as "o->is_forwarded()" 268 if (!test_mark->is_marked()) { 269 bool new_obj_is_tenured = false; 270 size_t new_obj_size = o->size(); 271 272 // Find the objects age, MT safe. 273 int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ? 274 test_mark->displaced_mark_helper()->age() : test_mark->age(); 275 276 // Try allocating obj in to-space (unless too old) 277 if (age < PSScavenge::tenuring_threshold()) { 278 new_obj = (oop) _young_lab.allocate(new_obj_size); 279 if (new_obj == NULL && !_young_gen_is_full) { 280 // Do we allocate directly, or flush and refill? 281 if (new_obj_size > (YoungPLABSize / 2)) { 282 // Allocate this object directly 283 new_obj = (oop)young_space()->cas_allocate(new_obj_size); 284 } else { 285 // Flush and fill 286 _young_lab.flush(); 287 288 HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize); 289 if (lab_base != NULL) { 290 _young_lab.initialize(MemRegion(lab_base, YoungPLABSize)); 291 // Try the young lab allocation again. 292 new_obj = (oop) _young_lab.allocate(new_obj_size); 293 } else { 294 _young_gen_is_full = true; 295 } 296 } 297 } 298 } 299 300 // Otherwise try allocating obj tenured 301 if (new_obj == NULL) { 302 #ifndef PRODUCT 303 if (Universe::heap()->promotion_should_fail()) { 304 return oop_promotion_failed(o, test_mark); 305 } 306 #endif // #ifndef PRODUCT 307 308 new_obj = (oop) _old_lab.allocate(new_obj_size); 309 new_obj_is_tenured = true; 310 311 if (new_obj == NULL) { 312 if (!_old_gen_is_full) { 313 // Do we allocate directly, or flush and refill? 314 if (new_obj_size > (OldPLABSize / 2)) { 315 // Allocate this object directly 316 new_obj = (oop)old_gen()->cas_allocate(new_obj_size); 317 } else { 318 // Flush and fill 319 _old_lab.flush(); 320 321 HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize); 322 if(lab_base != NULL) { 323 _old_lab.initialize(MemRegion(lab_base, OldPLABSize)); 324 // Try the old lab allocation again. 325 new_obj = (oop) _old_lab.allocate(new_obj_size); 326 } 327 } 328 } 329 330 // This is the promotion failed test, and code handling. 331 // The code belongs here for two reasons. It is slightly 332 // different thatn the code below, and cannot share the 333 // CAS testing code. Keeping the code here also minimizes 334 // the impact on the common case fast path code. 335 336 if (new_obj == NULL) { 337 _old_gen_is_full = true; 338 return oop_promotion_failed(o, test_mark); 339 } 340 } 341 } 342 343 assert(new_obj != NULL, "allocation should have succeeded"); 344 345 // Copy obj 346 Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size); 347 348 // Now we have to CAS in the header. 349 if (o->cas_forward_to(new_obj, test_mark)) { 350 // We won any races, we "own" this object. 351 assert(new_obj == o->forwardee(), "Sanity"); 352 353 // Increment age if obj still in new generation. Now that 354 // we're dealing with a markOop that cannot change, it is 355 // okay to use the non mt safe oop methods. 356 if (!new_obj_is_tenured) { 357 new_obj->incr_age(); 358 assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj"); 359 } 360 361 // Do the size comparison first with new_obj_size, which we 362 // already have. Hopefully, only a few objects are larger than 363 // _min_array_size_for_chunking, and most of them will be arrays. 364 // So, the is->objArray() test would be very infrequent. 365 if (new_obj_size > _min_array_size_for_chunking && 366 new_obj->is_objArray() && 367 PSChunkLargeArrays) { 368 // we'll chunk it 369 oop* const masked_o = mask_chunked_array_oop(o); 370 push_depth(masked_o); 371 TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes); 372 } else { 373 // we'll just push its contents 374 new_obj->push_contents(this); 375 } 376 } else { 377 // We lost, someone else "owns" this object 378 guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed."); 379 380 // Try to deallocate the space. If it was directly allocated we cannot 381 // deallocate it, so we have to test. If the deallocation fails, 382 // overwrite with a filler object. 383 if (new_obj_is_tenured) { 384 if (!_old_lab.unallocate_object(new_obj)) { 385 CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size); 386 } 387 } else if (!_young_lab.unallocate_object(new_obj)) { 388 CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size); 389 } 390 391 // don't update this before the unallocation! 392 new_obj = o->forwardee(); 393 } 394 } else { 395 assert(o->is_forwarded(), "Sanity"); 396 new_obj = o->forwardee(); 397 } 398 399 #ifdef DEBUG 400 // This code must come after the CAS test, or it will print incorrect 401 // information. 402 if (TraceScavenge) { 403 gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}", 404 PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring", 405 new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size()); 406 } 407 #endif 408 409 return new_obj; 410 } 411 412 template <class T> void PSPromotionManager::process_array_chunk_work( 413 oop obj, 414 int start, int end) { 415 assert(start < end, "invariant"); 416 T* const base = (T*)objArrayOop(obj)->base(); 417 T* p = base + start; 418 T* const chunk_end = base + end; 419 while (p < chunk_end) { 420 if (PSScavenge::should_scavenge(p)) { 421 claim_or_forward_depth(p); 422 } 423 ++p; 424 } 425 } 426 427 void PSPromotionManager::process_array_chunk(oop old) { 428 assert(PSChunkLargeArrays, "invariant"); 429 assert(old->is_objArray(), "invariant"); 430 assert(old->is_forwarded(), "invariant"); 431 432 TASKQUEUE_STATS_ONLY(++_array_chunks_processed); 433 434 oop const obj = old->forwardee(); 435 436 int start; 437 int const end = arrayOop(old)->length(); 438 if (end > (int) _min_array_size_for_chunking) { 439 // we'll chunk more 440 start = end - _array_chunk_size; 441 assert(start > 0, "invariant"); 442 arrayOop(old)->set_length(start); 443 push_depth(mask_chunked_array_oop(old)); 444 TASKQUEUE_STATS_ONLY(++_masked_pushes); 445 } else { 446 // this is the final chunk for this array 447 start = 0; 448 int const actual_length = arrayOop(obj)->length(); 449 arrayOop(old)->set_length(actual_length); 450 } 451 452 if (UseCompressedOops) { 453 process_array_chunk_work<narrowOop>(obj, start, end); 454 } else { 455 process_array_chunk_work<oop>(obj, start, end); 456 } 457 } 458 459 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) { 460 assert(_old_gen_is_full || PromotionFailureALot, "Sanity"); 461 462 // Attempt to CAS in the header. 463 // This tests if the header is still the same as when 464 // this started. If it is the same (i.e., no forwarding 465 // pointer has been installed), then this thread owns 466 // it. 467 if (obj->cas_forward_to(obj, obj_mark)) { 468 // We won any races, we "own" this object. 469 assert(obj == obj->forwardee(), "Sanity"); 470 471 obj->push_contents(this); 472 473 // Save the mark if needed 474 PSScavenge::oop_promotion_failed(obj, obj_mark); 475 } else { 476 // We lost, someone else "owns" this object 477 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed."); 478 479 // No unallocation to worry about. 480 obj = obj->forwardee(); 481 } 482 483 #ifdef DEBUG 484 if (TraceScavenge) { 485 gclog_or_tty->print_cr("{%s %s 0x%x (%d)}", 486 "promotion-failure", 487 obj->blueprint()->internal_name(), 488 obj, obj->size()); 489 490 } 491 #endif 492 493 return obj; 494 }