1 /* 2 * Copyright (c) 2001, 2014, 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/g1/concurrentG1Refine.hpp" 27 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 28 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp" 29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 30 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 31 #include "gc_implementation/g1/g1HotCardCache.hpp" 32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 33 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 34 #include "gc_implementation/g1/g1RemSet.inline.hpp" 35 #include "gc_implementation/g1/heapRegionManager.inline.hpp" 36 #include "gc_implementation/g1/heapRegionRemSet.hpp" 37 #include "memory/iterator.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "utilities/globalDefinitions.hpp" 40 #include "utilities/intHisto.hpp" 41 42 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 43 44 #define CARD_REPEAT_HISTO 0 45 46 #if CARD_REPEAT_HISTO 47 static size_t ct_freq_sz; 48 static jbyte* ct_freq = NULL; 49 50 void init_ct_freq_table(size_t heap_sz_bytes) { 51 if (ct_freq == NULL) { 52 ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size; 53 ct_freq = new jbyte[ct_freq_sz]; 54 for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0; 55 } 56 } 57 58 void ct_freq_note_card(size_t index) { 59 assert(0 <= index && index < ct_freq_sz, "Bounds error."); 60 if (ct_freq[index] < 100) { ct_freq[index]++; } 61 } 62 63 static IntHistogram card_repeat_count(10, 10); 64 65 void ct_freq_update_histo_and_reset() { 66 for (size_t j = 0; j < ct_freq_sz; j++) { 67 card_repeat_count.add_entry(ct_freq[j]); 68 ct_freq[j] = 0; 69 } 70 71 } 72 #endif 73 74 G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs) 75 : _g1(g1), _conc_refine_cards(0), 76 _ct_bs(ct_bs), _g1p(_g1->g1_policy()), 77 _cg1r(g1->concurrent_g1_refine()), 78 _cset_rs_update_cl(NULL), 79 _cards_scanned(NULL), _total_cards_scanned(0), 80 _prev_period_summary() 81 { 82 _seq_task = new SubTasksDone(NumSeqTasks); 83 _cset_rs_update_cl = NEW_C_HEAP_ARRAY(OopsInHeapRegionClosure*, n_workers(), mtGC); 84 for (uint i = 0; i < n_workers(); i++) { 85 _cset_rs_update_cl[i] = NULL; 86 } 87 if (G1SummarizeRSetStats) { 88 _prev_period_summary.initialize(this); 89 } 90 } 91 92 G1RemSet::~G1RemSet() { 93 delete _seq_task; 94 for (uint i = 0; i < n_workers(); i++) { 95 assert(_cset_rs_update_cl[i] == NULL, "it should be"); 96 } 97 FREE_C_HEAP_ARRAY(OopsInHeapRegionClosure*, _cset_rs_update_cl, mtGC); 98 } 99 100 void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) { 101 if (_g1->is_in_g1_reserved(mr.start())) { 102 _n += (int) ((mr.byte_size() / CardTableModRefBS::card_size)); 103 if (_start_first == NULL) _start_first = mr.start(); 104 } 105 } 106 107 class ScanRSClosure : public HeapRegionClosure { 108 size_t _cards_done, _cards; 109 G1CollectedHeap* _g1h; 110 111 OopsInHeapRegionClosure* _oc; 112 CodeBlobClosure* _code_root_cl; 113 114 G1BlockOffsetSharedArray* _bot_shared; 115 G1SATBCardTableModRefBS *_ct_bs; 116 117 double _strong_code_root_scan_time_sec; 118 uint _worker_i; 119 int _block_size; 120 bool _try_claimed; 121 122 public: 123 ScanRSClosure(OopsInHeapRegionClosure* oc, 124 CodeBlobClosure* code_root_cl, 125 uint worker_i) : 126 _oc(oc), 127 _code_root_cl(code_root_cl), 128 _strong_code_root_scan_time_sec(0.0), 129 _cards(0), 130 _cards_done(0), 131 _worker_i(worker_i), 132 _try_claimed(false) 133 { 134 _g1h = G1CollectedHeap::heap(); 135 _bot_shared = _g1h->bot_shared(); 136 _ct_bs = _g1h->g1_barrier_set(); 137 _block_size = MAX2<int>(G1RSetScanBlockSize, 1); 138 } 139 140 void set_try_claimed() { _try_claimed = true; } 141 142 void scanCard(size_t index, HeapRegion *r) { 143 // Stack allocate the DirtyCardToOopClosure instance 144 HeapRegionDCTOC cl(_g1h, r, _oc, 145 CardTableModRefBS::Precise, 146 HeapRegionDCTOC::IntoCSFilterKind); 147 148 // Set the "from" region in the closure. 149 _oc->set_region(r); 150 HeapWord* card_start = _bot_shared->address_for_index(index); 151 HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words; 152 Space *sp = SharedHeap::heap()->space_containing(card_start); 153 MemRegion sm_region = sp->used_region_at_save_marks(); 154 MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end)); 155 if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) { 156 // We make the card as "claimed" lazily (so races are possible 157 // but they're benign), which reduces the number of duplicate 158 // scans (the rsets of the regions in the cset can intersect). 159 _ct_bs->set_card_claimed(index); 160 _cards_done++; 161 cl.do_MemRegion(mr); 162 } 163 } 164 165 void printCard(HeapRegion* card_region, size_t card_index, 166 HeapWord* card_start) { 167 gclog_or_tty->print_cr("T %u Region [" PTR_FORMAT ", " PTR_FORMAT ") " 168 "RS names card " SIZE_FORMAT_HEX ": " 169 "[" PTR_FORMAT ", " PTR_FORMAT ")", 170 _worker_i, 171 card_region->bottom(), card_region->end(), 172 card_index, 173 card_start, card_start + G1BlockOffsetSharedArray::N_words); 174 } 175 176 void scan_strong_code_roots(HeapRegion* r) { 177 double scan_start = os::elapsedTime(); 178 r->strong_code_roots_do(_code_root_cl); 179 _strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start); 180 } 181 182 bool doHeapRegion(HeapRegion* r) { 183 assert(r->in_collection_set(), "should only be called on elements of CS."); 184 HeapRegionRemSet* hrrs = r->rem_set(); 185 if (hrrs->iter_is_complete()) return false; // All done. 186 if (!_try_claimed && !hrrs->claim_iter()) return false; 187 // If we ever free the collection set concurrently, we should also 188 // clear the card table concurrently therefore we won't need to 189 // add regions of the collection set to the dirty cards region. 190 _g1h->push_dirty_cards_region(r); 191 // If we didn't return above, then 192 // _try_claimed || r->claim_iter() 193 // is true: either we're supposed to work on claimed-but-not-complete 194 // regions, or we successfully claimed the region. 195 196 HeapRegionRemSetIterator iter(hrrs); 197 size_t card_index; 198 199 // We claim cards in block so as to reduce the contention. The block size is determined by 200 // the G1RSetScanBlockSize parameter. 201 size_t jump_to_card = hrrs->iter_claimed_next(_block_size); 202 for (size_t current_card = 0; iter.has_next(card_index); current_card++) { 203 if (current_card >= jump_to_card + _block_size) { 204 jump_to_card = hrrs->iter_claimed_next(_block_size); 205 } 206 if (current_card < jump_to_card) continue; 207 HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index); 208 #if 0 209 gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n", 210 card_start, card_start + CardTableModRefBS::card_size_in_words); 211 #endif 212 213 HeapRegion* card_region = _g1h->heap_region_containing(card_start); 214 _cards++; 215 216 if (!card_region->is_on_dirty_cards_region_list()) { 217 _g1h->push_dirty_cards_region(card_region); 218 } 219 220 // If the card is dirty, then we will scan it during updateRS. 221 if (!card_region->in_collection_set() && 222 !_ct_bs->is_card_dirty(card_index)) { 223 scanCard(card_index, card_region); 224 } 225 } 226 if (!_try_claimed) { 227 // Scan the strong code root list attached to the current region 228 scan_strong_code_roots(r); 229 230 hrrs->set_iter_complete(); 231 } 232 return false; 233 } 234 235 double strong_code_root_scan_time_sec() { 236 return _strong_code_root_scan_time_sec; 237 } 238 239 size_t cards_done() { return _cards_done;} 240 size_t cards_looked_up() { return _cards;} 241 }; 242 243 void G1RemSet::scanRS(OopsInHeapRegionClosure* oc, 244 CodeBlobClosure* code_root_cl, 245 uint worker_i) { 246 double rs_time_start = os::elapsedTime(); 247 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i); 248 249 ScanRSClosure scanRScl(oc, code_root_cl, worker_i); 250 251 _g1->collection_set_iterate_from(startRegion, &scanRScl); 252 scanRScl.set_try_claimed(); 253 _g1->collection_set_iterate_from(startRegion, &scanRScl); 254 255 double scan_rs_time_sec = (os::elapsedTime() - rs_time_start) 256 - scanRScl.strong_code_root_scan_time_sec(); 257 258 assert(_cards_scanned != NULL, "invariant"); 259 _cards_scanned[worker_i] = scanRScl.cards_done(); 260 261 _g1p->phase_times()->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0); 262 _g1p->phase_times()->record_strong_code_root_scan_time(worker_i, 263 scanRScl.strong_code_root_scan_time_sec() * 1000.0); 264 } 265 266 // Closure used for updating RSets and recording references that 267 // point into the collection set. Only called during an 268 // evacuation pause. 269 270 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure { 271 G1RemSet* _g1rs; 272 DirtyCardQueue* _into_cset_dcq; 273 public: 274 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h, 275 DirtyCardQueue* into_cset_dcq) : 276 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq) 277 {} 278 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 279 // The only time we care about recording cards that 280 // contain references that point into the collection set 281 // is during RSet updating within an evacuation pause. 282 // In this case worker_i should be the id of a GC worker thread. 283 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause"); 284 assert(worker_i < ParallelGCThreads, "should be a GC worker"); 285 286 if (_g1rs->refine_card(card_ptr, worker_i, true)) { 287 // 'card_ptr' contains references that point into the collection 288 // set. We need to record the card in the DCQS 289 // (G1CollectedHeap::into_cset_dirty_card_queue_set()) 290 // that's used for that purpose. 291 // 292 // Enqueue the card 293 _into_cset_dcq->enqueue(card_ptr); 294 } 295 return true; 296 } 297 }; 298 299 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i) { 300 double start = os::elapsedTime(); 301 // Apply the given closure to all remaining log entries. 302 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq); 303 304 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i); 305 306 // Now there should be no dirty cards. 307 if (G1RSLogCheckCardTable) { 308 CountNonCleanMemRegionClosure cl(_g1); 309 _ct_bs->mod_card_iterate(&cl); 310 // XXX This isn't true any more: keeping cards of young regions 311 // marked dirty broke it. Need some reasonable fix. 312 guarantee(cl.n() == 0, "Card table should be clean."); 313 } 314 315 _g1p->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0); 316 } 317 318 void G1RemSet::cleanupHRRS() { 319 HeapRegionRemSet::cleanup(); 320 } 321 322 void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc, 323 CodeBlobClosure* code_root_cl, 324 uint worker_i) { 325 #if CARD_REPEAT_HISTO 326 ct_freq_update_histo_and_reset(); 327 #endif 328 329 // We cache the value of 'oc' closure into the appropriate slot in the 330 // _cset_rs_update_cl for this worker 331 assert(worker_i < n_workers(), "sanity"); 332 _cset_rs_update_cl[worker_i] = oc; 333 334 // A DirtyCardQueue that is used to hold cards containing references 335 // that point into the collection set. This DCQ is associated with a 336 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal 337 // circumstances (i.e. the pause successfully completes), these cards 338 // are just discarded (there's no need to update the RSets of regions 339 // that were in the collection set - after the pause these regions 340 // are wholly 'free' of live objects. In the event of an evacuation 341 // failure the cards/buffers in this queue set are passed to the 342 // DirtyCardQueueSet that is used to manage RSet updates 343 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 344 345 updateRS(&into_cset_dcq, worker_i); 346 scanRS(oc, code_root_cl, worker_i); 347 348 // We now clear the cached values of _cset_rs_update_cl for this worker 349 _cset_rs_update_cl[worker_i] = NULL; 350 } 351 352 void G1RemSet::prepare_for_oops_into_collection_set_do() { 353 cleanupHRRS(); 354 _g1->set_refine_cte_cl_concurrency(false); 355 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 356 dcqs.concatenate_logs(); 357 358 guarantee( _cards_scanned == NULL, "invariant" ); 359 _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC); 360 for (uint i = 0; i < n_workers(); ++i) { 361 _cards_scanned[i] = 0; 362 } 363 _total_cards_scanned = 0; 364 } 365 366 void G1RemSet::cleanup_after_oops_into_collection_set_do() { 367 guarantee( _cards_scanned != NULL, "invariant" ); 368 _total_cards_scanned = 0; 369 for (uint i = 0; i < n_workers(); ++i) { 370 _total_cards_scanned += _cards_scanned[i]; 371 } 372 FREE_C_HEAP_ARRAY(size_t, _cards_scanned, mtGC); 373 _cards_scanned = NULL; 374 // Cleanup after copy 375 _g1->set_refine_cte_cl_concurrency(true); 376 // Set all cards back to clean. 377 _g1->cleanUpCardTable(); 378 379 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set(); 380 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num(); 381 382 if (_g1->evacuation_failed()) { 383 double restore_remembered_set_start = os::elapsedTime(); 384 385 // Restore remembered sets for the regions pointing into the collection set. 386 // We just need to transfer the completed buffers from the DirtyCardQueueSet 387 // used to hold cards that contain references that point into the collection set 388 // to the DCQS used to hold the deferred RS updates. 389 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs); 390 _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0); 391 } 392 393 // Free any completed buffers in the DirtyCardQueueSet used to hold cards 394 // which contain references that point into the collection. 395 _g1->into_cset_dirty_card_queue_set().clear(); 396 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0, 397 "all buffers should be freed"); 398 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers(); 399 } 400 401 class ScrubRSClosure: public HeapRegionClosure { 402 G1CollectedHeap* _g1h; 403 BitMap* _region_bm; 404 BitMap* _card_bm; 405 CardTableModRefBS* _ctbs; 406 public: 407 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) : 408 _g1h(G1CollectedHeap::heap()), 409 _region_bm(region_bm), _card_bm(card_bm), 410 _ctbs(_g1h->g1_barrier_set()) {} 411 412 bool doHeapRegion(HeapRegion* r) { 413 if (!r->is_continues_humongous()) { 414 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm); 415 } 416 return false; 417 } 418 }; 419 420 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer *hrclaimer) { 421 ScrubRSClosure scrub_cl(region_bm, card_bm); 422 _g1->heap_region_par_iterate(&scrub_cl, worker_num, hrclaimer); 423 } 424 425 G1TriggerClosure::G1TriggerClosure() : 426 _triggered(false) { } 427 428 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl, 429 OopClosure* oop_cl) : 430 _trigger_cl(t_cl), _oop_cl(oop_cl) { } 431 432 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) : 433 _c1(c1), _c2(c2) { } 434 435 G1UpdateRSOrPushRefOopClosure:: 436 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h, 437 G1RemSet* rs, 438 OopsInHeapRegionClosure* push_ref_cl, 439 bool record_refs_into_cset, 440 uint worker_i) : 441 _g1(g1h), _g1_rem_set(rs), _from(NULL), 442 _record_refs_into_cset(record_refs_into_cset), 443 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { } 444 445 // Returns true if the given card contains references that point 446 // into the collection set, if we're checking for such references; 447 // false otherwise. 448 449 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i, 450 bool check_for_refs_into_cset) { 451 assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)), 452 err_msg("Card at "PTR_FORMAT" index "SIZE_FORMAT" representing heap at "PTR_FORMAT" (%u) must be in committed heap", 453 p2i(card_ptr), 454 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)), 455 _ct_bs->addr_for(card_ptr), 456 _g1->addr_to_region(_ct_bs->addr_for(card_ptr)))); 457 458 // If the card is no longer dirty, nothing to do. 459 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 460 // No need to return that this card contains refs that point 461 // into the collection set. 462 return false; 463 } 464 465 // Construct the region representing the card. 466 HeapWord* start = _ct_bs->addr_for(card_ptr); 467 // And find the region containing it. 468 HeapRegion* r = _g1->heap_region_containing(start); 469 470 // Why do we have to check here whether a card is on a young region, 471 // given that we dirty young regions and, as a result, the 472 // post-barrier is supposed to filter them out and never to enqueue 473 // them? When we allocate a new region as the "allocation region" we 474 // actually dirty its cards after we release the lock, since card 475 // dirtying while holding the lock was a performance bottleneck. So, 476 // as a result, it is possible for other threads to actually 477 // allocate objects in the region (after the acquire the lock) 478 // before all the cards on the region are dirtied. This is unlikely, 479 // and it doesn't happen often, but it can happen. So, the extra 480 // check below filters out those cards. 481 if (r->is_young()) { 482 return false; 483 } 484 485 // While we are processing RSet buffers during the collection, we 486 // actually don't want to scan any cards on the collection set, 487 // since we don't want to update remembered sets with entries that 488 // point into the collection set, given that live objects from the 489 // collection set are about to move and such entries will be stale 490 // very soon. This change also deals with a reliability issue which 491 // involves scanning a card in the collection set and coming across 492 // an array that was being chunked and looking malformed. Note, 493 // however, that if evacuation fails, we have to scan any objects 494 // that were not moved and create any missing entries. 495 if (r->in_collection_set()) { 496 return false; 497 } 498 499 // The result from the hot card cache insert call is either: 500 // * pointer to the current card 501 // (implying that the current card is not 'hot'), 502 // * null 503 // (meaning we had inserted the card ptr into the "hot" card cache, 504 // which had some headroom), 505 // * a pointer to a "hot" card that was evicted from the "hot" cache. 506 // 507 508 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 509 if (hot_card_cache->use_cache()) { 510 assert(!check_for_refs_into_cset, "sanity"); 511 assert(!SafepointSynchronize::is_at_safepoint(), "sanity"); 512 513 card_ptr = hot_card_cache->insert(card_ptr); 514 if (card_ptr == NULL) { 515 // There was no eviction. Nothing to do. 516 return false; 517 } 518 519 start = _ct_bs->addr_for(card_ptr); 520 r = _g1->heap_region_containing(start); 521 522 // Checking whether the region we got back from the cache 523 // is young here is inappropriate. The region could have been 524 // freed, reallocated and tagged as young while in the cache. 525 // Hence we could see its young type change at any time. 526 } 527 528 // Don't use addr_for(card_ptr + 1) which can ask for 529 // a card beyond the heap. This is not safe without a perm 530 // gen at the upper end of the heap. 531 HeapWord* end = start + CardTableModRefBS::card_size_in_words; 532 MemRegion dirtyRegion(start, end); 533 534 #if CARD_REPEAT_HISTO 535 init_ct_freq_table(_g1->max_capacity()); 536 ct_freq_note_card(_ct_bs->index_for(start)); 537 #endif 538 539 OopsInHeapRegionClosure* oops_in_heap_closure = NULL; 540 if (check_for_refs_into_cset) { 541 // ConcurrentG1RefineThreads have worker numbers larger than what 542 // _cset_rs_update_cl[] is set up to handle. But those threads should 543 // only be active outside of a collection which means that when they 544 // reach here they should have check_for_refs_into_cset == false. 545 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length"); 546 oops_in_heap_closure = _cset_rs_update_cl[worker_i]; 547 } 548 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1, 549 _g1->g1_rem_set(), 550 oops_in_heap_closure, 551 check_for_refs_into_cset, 552 worker_i); 553 update_rs_oop_cl.set_from(r); 554 555 G1TriggerClosure trigger_cl; 556 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl); 557 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl); 558 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl); 559 560 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r, 561 (check_for_refs_into_cset ? 562 (OopClosure*)&mux : 563 (OopClosure*)&update_rs_oop_cl)); 564 565 // The region for the current card may be a young region. The 566 // current card may have been a card that was evicted from the 567 // card cache. When the card was inserted into the cache, we had 568 // determined that its region was non-young. While in the cache, 569 // the region may have been freed during a cleanup pause, reallocated 570 // and tagged as young. 571 // 572 // We wish to filter out cards for such a region but the current 573 // thread, if we're running concurrently, may "see" the young type 574 // change at any time (so an earlier "is_young" check may pass or 575 // fail arbitrarily). We tell the iteration code to perform this 576 // filtering when it has been determined that there has been an actual 577 // allocation in this region and making it safe to check the young type. 578 bool filter_young = true; 579 580 HeapWord* stop_point = 581 r->oops_on_card_seq_iterate_careful(dirtyRegion, 582 &filter_then_update_rs_oop_cl, 583 filter_young, 584 card_ptr); 585 586 // If stop_point is non-null, then we encountered an unallocated region 587 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the 588 // card and re-enqueue: if we put off the card until a GC pause, then the 589 // unallocated portion will be filled in. Alternatively, we might try 590 // the full complexity of the technique used in "regular" precleaning. 591 if (stop_point != NULL) { 592 // The card might have gotten re-dirtied and re-enqueued while we 593 // worked. (In fact, it's pretty likely.) 594 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 595 *card_ptr = CardTableModRefBS::dirty_card_val(); 596 MutexLockerEx x(Shared_DirtyCardQ_lock, 597 Mutex::_no_safepoint_check_flag); 598 DirtyCardQueue* sdcq = 599 JavaThread::dirty_card_queue_set().shared_dirty_card_queue(); 600 sdcq->enqueue(card_ptr); 601 } 602 } else { 603 _conc_refine_cards++; 604 } 605 606 // This gets set to true if the card being refined has 607 // references that point into the collection set. 608 bool has_refs_into_cset = trigger_cl.triggered(); 609 610 // We should only be detecting that the card contains references 611 // that point into the collection set if the current thread is 612 // a GC worker thread. 613 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(), 614 "invalid result at non safepoint"); 615 616 return has_refs_into_cset; 617 } 618 619 void G1RemSet::print_periodic_summary_info(const char* header) { 620 G1RemSetSummary current; 621 current.initialize(this); 622 623 _prev_period_summary.subtract_from(¤t); 624 print_summary_info(&_prev_period_summary, header); 625 626 _prev_period_summary.set(¤t); 627 } 628 629 void G1RemSet::print_summary_info() { 630 G1RemSetSummary current; 631 current.initialize(this); 632 633 print_summary_info(¤t, " Cumulative RS summary"); 634 } 635 636 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) { 637 assert(summary != NULL, "just checking"); 638 639 if (header != NULL) { 640 gclog_or_tty->print_cr("%s", header); 641 } 642 643 #if CARD_REPEAT_HISTO 644 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: "); 645 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number."); 646 card_repeat_count.print_on(gclog_or_tty); 647 #endif 648 649 summary->print_on(gclog_or_tty); 650 } 651 652 void G1RemSet::prepare_for_verify() { 653 if (G1HRRSFlushLogBuffersOnVerify && 654 (VerifyBeforeGC || VerifyAfterGC) 655 && (!_g1->full_collection() || G1VerifyRSetsDuringFullGC)) { 656 cleanupHRRS(); 657 _g1->set_refine_cte_cl_concurrency(false); 658 if (SafepointSynchronize::is_at_safepoint()) { 659 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 660 dcqs.concatenate_logs(); 661 } 662 663 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 664 bool use_hot_card_cache = hot_card_cache->use_cache(); 665 hot_card_cache->set_use_cache(false); 666 667 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 668 updateRS(&into_cset_dcq, 0); 669 _g1->into_cset_dirty_card_queue_set().clear(); 670 671 hot_card_cache->set_use_cache(use_hot_card_cache); 672 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 673 } 674 }