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