1 /* 2 * Copyright (c) 2001, 2015, 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/g1/concurrentG1Refine.hpp" 27 #include "gc/g1/concurrentG1RefineThread.hpp" 28 #include "gc/g1/g1BlockOffsetTable.inline.hpp" 29 #include "gc/g1/g1CollectedHeap.inline.hpp" 30 #include "gc/g1/g1CollectorPolicy.hpp" 31 #include "gc/g1/g1GCPhaseTimes.hpp" 32 #include "gc/g1/g1HotCardCache.hpp" 33 #include "gc/g1/g1OopClosures.inline.hpp" 34 #include "gc/g1/g1RemSet.inline.hpp" 35 #include "gc/g1/heapRegionManager.inline.hpp" 36 #include "gc/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 #include "utilities/stack.inline.hpp" 42 43 #define CARD_REPEAT_HISTO 0 44 45 #if CARD_REPEAT_HISTO 46 static size_t ct_freq_sz; 47 static jbyte* ct_freq = NULL; 48 49 void init_ct_freq_table(size_t heap_sz_bytes) { 50 if (ct_freq == NULL) { 51 ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size; 52 ct_freq = new jbyte[ct_freq_sz]; 53 for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0; 54 } 55 } 56 57 void ct_freq_note_card(size_t index) { 58 assert(0 <= index && index < ct_freq_sz, "Bounds error."); 59 if (ct_freq[index] < 100) { ct_freq[index]++; } 60 } 61 62 static IntHistogram card_repeat_count(10, 10); 63 64 void ct_freq_update_histo_and_reset() { 65 for (size_t j = 0; j < ct_freq_sz; j++) { 66 card_repeat_count.add_entry(ct_freq[j]); 67 ct_freq[j] = 0; 68 } 69 70 } 71 #endif 72 73 G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs) 74 : _g1(g1), _conc_refine_cards(0), 75 _ct_bs(ct_bs), _g1p(_g1->g1_policy()), 76 _cg1r(g1->concurrent_g1_refine()), 77 _cset_rs_update_cl(NULL), 78 _cards_scanned(NULL), _total_cards_scanned(0), 79 _prev_period_summary() 80 { 81 _cset_rs_update_cl = NEW_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, n_workers(), mtGC); 82 for (uint i = 0; i < n_workers(); i++) { 83 _cset_rs_update_cl[i] = NULL; 84 } 85 if (G1SummarizeRSetStats) { 86 _prev_period_summary.initialize(this); 87 } 88 } 89 90 G1RemSet::~G1RemSet() { 91 for (uint i = 0; i < n_workers(); i++) { 92 assert(_cset_rs_update_cl[i] == NULL, "it should be"); 93 } 94 FREE_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, _cset_rs_update_cl); 95 } 96 97 class ScanRSClosure : public HeapRegionClosure { 98 size_t _cards_done, _cards; 99 G1CollectedHeap* _g1h; 100 101 G1ParPushHeapRSClosure* _oc; 102 CodeBlobClosure* _code_root_cl; 103 104 G1BlockOffsetSharedArray* _bot_shared; 105 G1SATBCardTableModRefBS *_ct_bs; 106 107 double _strong_code_root_scan_time_sec; 108 uint _worker_i; 109 size_t _block_size; 110 bool _try_claimed; 111 112 public: 113 ScanRSClosure(G1ParPushHeapRSClosure* oc, 114 CodeBlobClosure* code_root_cl, 115 uint worker_i) : 116 _oc(oc), 117 _code_root_cl(code_root_cl), 118 _strong_code_root_scan_time_sec(0.0), 119 _cards(0), 120 _cards_done(0), 121 _worker_i(worker_i), 122 _try_claimed(false) 123 { 124 _g1h = G1CollectedHeap::heap(); 125 _bot_shared = _g1h->bot_shared(); 126 _ct_bs = _g1h->g1_barrier_set(); 127 _block_size = MAX2<size_t>(G1RSetScanBlockSize, 1); 128 } 129 130 void set_try_claimed() { _try_claimed = true; } 131 132 void scanCard(size_t index, HeapRegion *r) { 133 // Stack allocate the DirtyCardToOopClosure instance 134 HeapRegionDCTOC cl(_g1h, r, _oc, 135 CardTableModRefBS::Precise); 136 137 // Set the "from" region in the closure. 138 _oc->set_region(r); 139 MemRegion card_region(_bot_shared->address_for_index(index), G1BlockOffsetSharedArray::N_words); 140 MemRegion pre_gc_allocated(r->bottom(), r->scan_top()); 141 MemRegion mr = pre_gc_allocated.intersection(card_region); 142 if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) { 143 // We make the card as "claimed" lazily (so races are possible 144 // but they're benign), which reduces the number of duplicate 145 // scans (the rsets of the regions in the cset can intersect). 146 _ct_bs->set_card_claimed(index); 147 _cards_done++; 148 cl.do_MemRegion(mr); 149 } 150 } 151 152 void printCard(HeapRegion* card_region, size_t card_index, 153 HeapWord* card_start) { 154 gclog_or_tty->print_cr("T %u Region [" PTR_FORMAT ", " PTR_FORMAT ") " 155 "RS names card " SIZE_FORMAT_HEX ": " 156 "[" PTR_FORMAT ", " PTR_FORMAT ")", 157 _worker_i, 158 p2i(card_region->bottom()), p2i(card_region->end()), 159 card_index, 160 p2i(card_start), p2i(card_start + G1BlockOffsetSharedArray::N_words)); 161 } 162 163 void scan_strong_code_roots(HeapRegion* r) { 164 double scan_start = os::elapsedTime(); 165 r->strong_code_roots_do(_code_root_cl); 166 _strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start); 167 } 168 169 bool doHeapRegion(HeapRegion* r) { 170 assert(r->in_collection_set(), "should only be called on elements of CS."); 171 HeapRegionRemSet* hrrs = r->rem_set(); 172 if (hrrs->iter_is_complete()) return false; // All done. 173 if (!_try_claimed && !hrrs->claim_iter()) return false; 174 // If we ever free the collection set concurrently, we should also 175 // clear the card table concurrently therefore we won't need to 176 // add regions of the collection set to the dirty cards region. 177 _g1h->push_dirty_cards_region(r); 178 // If we didn't return above, then 179 // _try_claimed || r->claim_iter() 180 // is true: either we're supposed to work on claimed-but-not-complete 181 // regions, or we successfully claimed the region. 182 183 HeapRegionRemSetIterator iter(hrrs); 184 size_t card_index; 185 186 // We claim cards in block so as to reduce the contention. The block size is determined by 187 // the G1RSetScanBlockSize parameter. 188 size_t jump_to_card = hrrs->iter_claimed_next(_block_size); 189 for (size_t current_card = 0; iter.has_next(card_index); current_card++) { 190 if (current_card >= jump_to_card + _block_size) { 191 jump_to_card = hrrs->iter_claimed_next(_block_size); 192 } 193 if (current_card < jump_to_card) continue; 194 HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index); 195 #if 0 196 gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n", 197 card_start, card_start + CardTableModRefBS::card_size_in_words); 198 #endif 199 200 HeapRegion* card_region = _g1h->heap_region_containing(card_start); 201 _cards++; 202 203 if (!card_region->is_on_dirty_cards_region_list()) { 204 _g1h->push_dirty_cards_region(card_region); 205 } 206 207 // If the card is dirty, then we will scan it during updateRS. 208 if (!card_region->in_collection_set() && 209 !_ct_bs->is_card_dirty(card_index)) { 210 scanCard(card_index, card_region); 211 } 212 } 213 if (!_try_claimed) { 214 // Scan the strong code root list attached to the current region 215 scan_strong_code_roots(r); 216 217 hrrs->set_iter_complete(); 218 } 219 return false; 220 } 221 222 double strong_code_root_scan_time_sec() { 223 return _strong_code_root_scan_time_sec; 224 } 225 226 size_t cards_done() { return _cards_done;} 227 size_t cards_looked_up() { return _cards;} 228 }; 229 230 void G1RemSet::scanRS(G1ParPushHeapRSClosure* oc, 231 CodeBlobClosure* code_root_cl, 232 uint worker_i) { 233 double rs_time_start = os::elapsedTime(); 234 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i); 235 236 ScanRSClosure scanRScl(oc, code_root_cl, worker_i); 237 238 _g1->collection_set_iterate_from(startRegion, &scanRScl); 239 scanRScl.set_try_claimed(); 240 _g1->collection_set_iterate_from(startRegion, &scanRScl); 241 242 double scan_rs_time_sec = (os::elapsedTime() - rs_time_start) 243 - scanRScl.strong_code_root_scan_time_sec(); 244 245 assert(_cards_scanned != NULL, "invariant"); 246 _cards_scanned[worker_i] = scanRScl.cards_done(); 247 248 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::ScanRS, worker_i, scan_rs_time_sec); 249 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::CodeRoots, worker_i, scanRScl.strong_code_root_scan_time_sec()); 250 } 251 252 // Closure used for updating RSets and recording references that 253 // point into the collection set. Only called during an 254 // evacuation pause. 255 256 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure { 257 G1RemSet* _g1rs; 258 DirtyCardQueue* _into_cset_dcq; 259 public: 260 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h, 261 DirtyCardQueue* into_cset_dcq) : 262 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq) 263 {} 264 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 265 // The only time we care about recording cards that 266 // contain references that point into the collection set 267 // is during RSet updating within an evacuation pause. 268 // In this case worker_i should be the id of a GC worker thread. 269 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause"); 270 assert(worker_i < ParallelGCThreads, "should be a GC worker"); 271 272 if (_g1rs->refine_card(card_ptr, worker_i, true)) { 273 // 'card_ptr' contains references that point into the collection 274 // set. We need to record the card in the DCQS 275 // (G1CollectedHeap::into_cset_dirty_card_queue_set()) 276 // that's used for that purpose. 277 // 278 // Enqueue the card 279 _into_cset_dcq->enqueue(card_ptr); 280 } 281 return true; 282 } 283 }; 284 285 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i) { 286 G1GCParPhaseTimesTracker x(_g1p->phase_times(), G1GCPhaseTimes::UpdateRS, worker_i); 287 // Apply the given closure to all remaining log entries. 288 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq); 289 290 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i); 291 } 292 293 void G1RemSet::cleanupHRRS() { 294 HeapRegionRemSet::cleanup(); 295 } 296 297 void G1RemSet::oops_into_collection_set_do(G1ParPushHeapRSClosure* oc, 298 CodeBlobClosure* code_root_cl, 299 uint worker_i) { 300 #if CARD_REPEAT_HISTO 301 ct_freq_update_histo_and_reset(); 302 #endif 303 304 // We cache the value of 'oc' closure into the appropriate slot in the 305 // _cset_rs_update_cl for this worker 306 assert(worker_i < n_workers(), "sanity"); 307 _cset_rs_update_cl[worker_i] = oc; 308 309 // A DirtyCardQueue that is used to hold cards containing references 310 // that point into the collection set. This DCQ is associated with a 311 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal 312 // circumstances (i.e. the pause successfully completes), these cards 313 // are just discarded (there's no need to update the RSets of regions 314 // that were in the collection set - after the pause these regions 315 // are wholly 'free' of live objects. In the event of an evacuation 316 // failure the cards/buffers in this queue set are passed to the 317 // DirtyCardQueueSet that is used to manage RSet updates 318 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 319 320 updateRS(&into_cset_dcq, worker_i); 321 scanRS(oc, code_root_cl, worker_i); 322 323 // We now clear the cached values of _cset_rs_update_cl for this worker 324 _cset_rs_update_cl[worker_i] = NULL; 325 } 326 327 void G1RemSet::prepare_for_oops_into_collection_set_do() { 328 cleanupHRRS(); 329 _g1->set_refine_cte_cl_concurrency(false); 330 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 331 dcqs.concatenate_logs(); 332 333 guarantee( _cards_scanned == NULL, "invariant" ); 334 _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC); 335 for (uint i = 0; i < n_workers(); ++i) { 336 _cards_scanned[i] = 0; 337 } 338 _total_cards_scanned = 0; 339 } 340 341 void G1RemSet::cleanup_after_oops_into_collection_set_do() { 342 guarantee( _cards_scanned != NULL, "invariant" ); 343 _total_cards_scanned = 0; 344 for (uint i = 0; i < n_workers(); ++i) { 345 _total_cards_scanned += _cards_scanned[i]; 346 } 347 FREE_C_HEAP_ARRAY(size_t, _cards_scanned); 348 _cards_scanned = NULL; 349 // Cleanup after copy 350 _g1->set_refine_cte_cl_concurrency(true); 351 // Set all cards back to clean. 352 _g1->cleanUpCardTable(); 353 354 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set(); 355 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num(); 356 357 if (_g1->evacuation_failed()) { 358 double restore_remembered_set_start = os::elapsedTime(); 359 360 // Restore remembered sets for the regions pointing into the collection set. 361 // We just need to transfer the completed buffers from the DirtyCardQueueSet 362 // used to hold cards that contain references that point into the collection set 363 // to the DCQS used to hold the deferred RS updates. 364 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs); 365 _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0); 366 } 367 368 // Free any completed buffers in the DirtyCardQueueSet used to hold cards 369 // which contain references that point into the collection. 370 _g1->into_cset_dirty_card_queue_set().clear(); 371 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0, 372 "all buffers should be freed"); 373 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers(); 374 } 375 376 class ScrubRSClosure: public HeapRegionClosure { 377 G1CollectedHeap* _g1h; 378 BitMap* _region_bm; 379 BitMap* _card_bm; 380 CardTableModRefBS* _ctbs; 381 public: 382 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) : 383 _g1h(G1CollectedHeap::heap()), 384 _region_bm(region_bm), _card_bm(card_bm), 385 _ctbs(_g1h->g1_barrier_set()) {} 386 387 bool doHeapRegion(HeapRegion* r) { 388 if (!r->is_continues_humongous()) { 389 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm); 390 } 391 return false; 392 } 393 }; 394 395 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer *hrclaimer) { 396 ScrubRSClosure scrub_cl(region_bm, card_bm); 397 _g1->heap_region_par_iterate(&scrub_cl, worker_num, hrclaimer); 398 } 399 400 G1TriggerClosure::G1TriggerClosure() : 401 _triggered(false) { } 402 403 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl, 404 OopClosure* oop_cl) : 405 _trigger_cl(t_cl), _oop_cl(oop_cl) { } 406 407 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) : 408 _c1(c1), _c2(c2) { } 409 410 G1UpdateRSOrPushRefOopClosure:: 411 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h, 412 G1RemSet* rs, 413 G1ParPushHeapRSClosure* push_ref_cl, 414 bool record_refs_into_cset, 415 uint worker_i) : 416 _g1(g1h), _g1_rem_set(rs), _from(NULL), 417 _record_refs_into_cset(record_refs_into_cset), 418 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { } 419 420 // Returns true if the given card contains references that point 421 // into the collection set, if we're checking for such references; 422 // false otherwise. 423 424 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i, 425 bool check_for_refs_into_cset) { 426 assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)), 427 err_msg("Card at " PTR_FORMAT " index " SIZE_FORMAT " representing heap at " PTR_FORMAT " (%u) must be in committed heap", 428 p2i(card_ptr), 429 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)), 430 p2i(_ct_bs->addr_for(card_ptr)), 431 _g1->addr_to_region(_ct_bs->addr_for(card_ptr)))); 432 433 // If the card is no longer dirty, nothing to do. 434 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 435 // No need to return that this card contains refs that point 436 // into the collection set. 437 return false; 438 } 439 440 // Construct the region representing the card. 441 HeapWord* start = _ct_bs->addr_for(card_ptr); 442 // And find the region containing it. 443 HeapRegion* r = _g1->heap_region_containing(start); 444 445 // Why do we have to check here whether a card is on a young region, 446 // given that we dirty young regions and, as a result, the 447 // post-barrier is supposed to filter them out and never to enqueue 448 // them? When we allocate a new region as the "allocation region" we 449 // actually dirty its cards after we release the lock, since card 450 // dirtying while holding the lock was a performance bottleneck. So, 451 // as a result, it is possible for other threads to actually 452 // allocate objects in the region (after the acquire the lock) 453 // before all the cards on the region are dirtied. This is unlikely, 454 // and it doesn't happen often, but it can happen. So, the extra 455 // check below filters out those cards. 456 if (r->is_young()) { 457 return false; 458 } 459 460 // While we are processing RSet buffers during the collection, we 461 // actually don't want to scan any cards on the collection set, 462 // since we don't want to update remembered sets with entries that 463 // point into the collection set, given that live objects from the 464 // collection set are about to move and such entries will be stale 465 // very soon. This change also deals with a reliability issue which 466 // involves scanning a card in the collection set and coming across 467 // an array that was being chunked and looking malformed. Note, 468 // however, that if evacuation fails, we have to scan any objects 469 // that were not moved and create any missing entries. 470 if (r->in_collection_set()) { 471 return false; 472 } 473 474 // The result from the hot card cache insert call is either: 475 // * pointer to the current card 476 // (implying that the current card is not 'hot'), 477 // * null 478 // (meaning we had inserted the card ptr into the "hot" card cache, 479 // which had some headroom), 480 // * a pointer to a "hot" card that was evicted from the "hot" cache. 481 // 482 483 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 484 if (hot_card_cache->use_cache()) { 485 assert(!check_for_refs_into_cset, "sanity"); 486 assert(!SafepointSynchronize::is_at_safepoint(), "sanity"); 487 488 card_ptr = hot_card_cache->insert(card_ptr); 489 if (card_ptr == NULL) { 490 // There was no eviction. Nothing to do. 491 return false; 492 } 493 494 start = _ct_bs->addr_for(card_ptr); 495 r = _g1->heap_region_containing(start); 496 497 // Checking whether the region we got back from the cache 498 // is young here is inappropriate. The region could have been 499 // freed, reallocated and tagged as young while in the cache. 500 // Hence we could see its young type change at any time. 501 } 502 503 // Don't use addr_for(card_ptr + 1) which can ask for 504 // a card beyond the heap. This is not safe without a perm 505 // gen at the upper end of the heap. 506 HeapWord* end = start + CardTableModRefBS::card_size_in_words; 507 MemRegion dirtyRegion(start, end); 508 509 #if CARD_REPEAT_HISTO 510 init_ct_freq_table(_g1->max_capacity()); 511 ct_freq_note_card(_ct_bs->index_for(start)); 512 #endif 513 514 G1ParPushHeapRSClosure* oops_in_heap_closure = NULL; 515 if (check_for_refs_into_cset) { 516 // ConcurrentG1RefineThreads have worker numbers larger than what 517 // _cset_rs_update_cl[] is set up to handle. But those threads should 518 // only be active outside of a collection which means that when they 519 // reach here they should have check_for_refs_into_cset == false. 520 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length"); 521 oops_in_heap_closure = _cset_rs_update_cl[worker_i]; 522 } 523 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1, 524 _g1->g1_rem_set(), 525 oops_in_heap_closure, 526 check_for_refs_into_cset, 527 worker_i); 528 update_rs_oop_cl.set_from(r); 529 530 G1TriggerClosure trigger_cl; 531 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl); 532 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl); 533 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl); 534 535 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r, 536 (check_for_refs_into_cset ? 537 (OopClosure*)&mux : 538 (OopClosure*)&update_rs_oop_cl)); 539 540 // The region for the current card may be a young region. The 541 // current card may have been a card that was evicted from the 542 // card cache. When the card was inserted into the cache, we had 543 // determined that its region was non-young. While in the cache, 544 // the region may have been freed during a cleanup pause, reallocated 545 // and tagged as young. 546 // 547 // We wish to filter out cards for such a region but the current 548 // thread, if we're running concurrently, may "see" the young type 549 // change at any time (so an earlier "is_young" check may pass or 550 // fail arbitrarily). We tell the iteration code to perform this 551 // filtering when it has been determined that there has been an actual 552 // allocation in this region and making it safe to check the young type. 553 bool filter_young = true; 554 555 HeapWord* stop_point = 556 r->oops_on_card_seq_iterate_careful(dirtyRegion, 557 &filter_then_update_rs_oop_cl, 558 filter_young, 559 card_ptr); 560 561 // If stop_point is non-null, then we encountered an unallocated region 562 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the 563 // card and re-enqueue: if we put off the card until a GC pause, then the 564 // unallocated portion will be filled in. Alternatively, we might try 565 // the full complexity of the technique used in "regular" precleaning. 566 if (stop_point != NULL) { 567 // The card might have gotten re-dirtied and re-enqueued while we 568 // worked. (In fact, it's pretty likely.) 569 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 570 *card_ptr = CardTableModRefBS::dirty_card_val(); 571 MutexLockerEx x(Shared_DirtyCardQ_lock, 572 Mutex::_no_safepoint_check_flag); 573 DirtyCardQueue* sdcq = 574 JavaThread::dirty_card_queue_set().shared_dirty_card_queue(); 575 sdcq->enqueue(card_ptr); 576 } 577 } else { 578 _conc_refine_cards++; 579 } 580 581 // This gets set to true if the card being refined has 582 // references that point into the collection set. 583 bool has_refs_into_cset = trigger_cl.triggered(); 584 585 // We should only be detecting that the card contains references 586 // that point into the collection set if the current thread is 587 // a GC worker thread. 588 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(), 589 "invalid result at non safepoint"); 590 591 return has_refs_into_cset; 592 } 593 594 void G1RemSet::print_periodic_summary_info(const char* header) { 595 G1RemSetSummary current; 596 current.initialize(this); 597 598 _prev_period_summary.subtract_from(¤t); 599 print_summary_info(&_prev_period_summary, header); 600 601 _prev_period_summary.set(¤t); 602 } 603 604 void G1RemSet::print_summary_info() { 605 G1RemSetSummary current; 606 current.initialize(this); 607 608 print_summary_info(¤t, " Cumulative RS summary"); 609 } 610 611 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) { 612 assert(summary != NULL, "just checking"); 613 614 if (header != NULL) { 615 gclog_or_tty->print_cr("%s", header); 616 } 617 618 #if CARD_REPEAT_HISTO 619 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: "); 620 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number."); 621 card_repeat_count.print_on(gclog_or_tty); 622 #endif 623 624 summary->print_on(gclog_or_tty); 625 } 626 627 void G1RemSet::prepare_for_verify() { 628 if (G1HRRSFlushLogBuffersOnVerify && 629 (VerifyBeforeGC || VerifyAfterGC) 630 && (!_g1->full_collection() || G1VerifyRSetsDuringFullGC)) { 631 cleanupHRRS(); 632 _g1->set_refine_cte_cl_concurrency(false); 633 if (SafepointSynchronize::is_at_safepoint()) { 634 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 635 dcqs.concatenate_logs(); 636 } 637 638 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 639 bool use_hot_card_cache = hot_card_cache->use_cache(); 640 hot_card_cache->set_use_cache(false); 641 642 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 643 updateRS(&into_cset_dcq, 0); 644 _g1->into_cset_dirty_card_queue_set().clear(); 645 646 hot_card_cache->set_use_cache(use_hot_card_cache); 647 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 648 } 649 }