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/g1CodeBlobClosure.hpp" 30 #include "gc/g1/g1CollectedHeap.inline.hpp" 31 #include "gc/g1/g1CollectorPolicy.hpp" 32 #include "gc/g1/g1GCPhaseTimes.hpp" 33 #include "gc/g1/g1HotCardCache.hpp" 34 #include "gc/g1/g1OopClosures.inline.hpp" 35 #include "gc/g1/g1RemSet.inline.hpp" 36 #include "gc/g1/heapRegionManager.inline.hpp" 37 #include "gc/g1/heapRegionRemSet.hpp" 38 #include "memory/iterator.hpp" 39 #include "oops/oop.inline.hpp" 40 #include "utilities/globalDefinitions.hpp" 41 #include "utilities/intHisto.hpp" 42 #include "utilities/stack.inline.hpp" 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 _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 size_t G1RemSet::scanRS(G1ParPushHeapRSClosure* oc, 231 OopClosure* non_heap_roots, 232 uint worker_i) { 233 double rs_time_start = os::elapsedTime(); 234 235 G1CodeBlobClosure code_root_cl(non_heap_roots); 236 237 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i); 238 239 ScanRSClosure scanRScl(oc, &code_root_cl, worker_i); 240 241 _g1->collection_set_iterate_from(startRegion, &scanRScl); 242 scanRScl.set_try_claimed(); 243 _g1->collection_set_iterate_from(startRegion, &scanRScl); 244 245 double scan_rs_time_sec = (os::elapsedTime() - rs_time_start) 246 - scanRScl.strong_code_root_scan_time_sec(); 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 return scanRScl.cards_done(); 252 } 253 254 // Closure used for updating RSets and recording references that 255 // point into the collection set. Only called during an 256 // evacuation pause. 257 258 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure { 259 G1RemSet* _g1rs; 260 DirtyCardQueue* _into_cset_dcq; 261 public: 262 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h, 263 DirtyCardQueue* into_cset_dcq) : 264 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq) 265 {} 266 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 267 // The only time we care about recording cards that 268 // contain references that point into the collection set 269 // is during RSet updating within an evacuation pause. 270 // In this case worker_i should be the id of a GC worker thread. 271 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause"); 272 assert(worker_i < ParallelGCThreads, "should be a GC worker"); 273 274 if (_g1rs->refine_card(card_ptr, worker_i, true)) { 275 // 'card_ptr' contains references that point into the collection 276 // set. We need to record the card in the DCQS 277 // (G1CollectedHeap::into_cset_dirty_card_queue_set()) 278 // that's used for that purpose. 279 // 280 // Enqueue the card 281 _into_cset_dcq->enqueue(card_ptr); 282 } 283 return true; 284 } 285 }; 286 287 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i) { 288 G1GCParPhaseTimesTracker x(_g1p->phase_times(), G1GCPhaseTimes::UpdateRS, worker_i); 289 // Apply the given closure to all remaining log entries. 290 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq); 291 292 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i); 293 } 294 295 void G1RemSet::cleanupHRRS() { 296 HeapRegionRemSet::cleanup(); 297 } 298 299 size_t G1RemSet::oops_into_collection_set_do(G1ParPushHeapRSClosure* oc, 300 OopClosure* non_heap_roots, 301 uint worker_i) { 302 #if CARD_REPEAT_HISTO 303 ct_freq_update_histo_and_reset(); 304 #endif 305 306 // We cache the value of 'oc' closure into the appropriate slot in the 307 // _cset_rs_update_cl for this worker 308 assert(worker_i < n_workers(), "sanity"); 309 _cset_rs_update_cl[worker_i] = oc; 310 311 // A DirtyCardQueue that is used to hold cards containing references 312 // that point into the collection set. This DCQ is associated with a 313 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal 314 // circumstances (i.e. the pause successfully completes), these cards 315 // are just discarded (there's no need to update the RSets of regions 316 // that were in the collection set - after the pause these regions 317 // are wholly 'free' of live objects. In the event of an evacuation 318 // failure the cards/buffers in this queue set are passed to the 319 // DirtyCardQueueSet that is used to manage RSet updates 320 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 321 322 updateRS(&into_cset_dcq, worker_i); 323 size_t cards_scanned = scanRS(oc, non_heap_roots, worker_i); 324 325 // We now clear the cached values of _cset_rs_update_cl for this worker 326 _cset_rs_update_cl[worker_i] = NULL; 327 return cards_scanned; 328 } 329 330 void G1RemSet::prepare_for_oops_into_collection_set_do() { 331 cleanupHRRS(); 332 _g1->set_refine_cte_cl_concurrency(false); 333 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 334 dcqs.concatenate_logs(); 335 } 336 337 void G1RemSet::cleanup_after_oops_into_collection_set_do() { 338 // Cleanup after copy 339 _g1->set_refine_cte_cl_concurrency(true); 340 // Set all cards back to clean. 341 _g1->cleanUpCardTable(); 342 343 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set(); 344 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num(); 345 346 if (_g1->evacuation_failed()) { 347 double restore_remembered_set_start = os::elapsedTime(); 348 349 // Restore remembered sets for the regions pointing into the collection set. 350 // We just need to transfer the completed buffers from the DirtyCardQueueSet 351 // used to hold cards that contain references that point into the collection set 352 // to the DCQS used to hold the deferred RS updates. 353 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs); 354 _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0); 355 } 356 357 // Free any completed buffers in the DirtyCardQueueSet used to hold cards 358 // which contain references that point into the collection. 359 _g1->into_cset_dirty_card_queue_set().clear(); 360 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0, 361 "all buffers should be freed"); 362 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers(); 363 } 364 365 class ScrubRSClosure: public HeapRegionClosure { 366 G1CollectedHeap* _g1h; 367 BitMap* _region_bm; 368 BitMap* _card_bm; 369 CardTableModRefBS* _ctbs; 370 public: 371 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) : 372 _g1h(G1CollectedHeap::heap()), 373 _region_bm(region_bm), _card_bm(card_bm), 374 _ctbs(_g1h->g1_barrier_set()) {} 375 376 bool doHeapRegion(HeapRegion* r) { 377 if (!r->is_continues_humongous()) { 378 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm); 379 } 380 return false; 381 } 382 }; 383 384 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer *hrclaimer) { 385 ScrubRSClosure scrub_cl(region_bm, card_bm); 386 _g1->heap_region_par_iterate(&scrub_cl, worker_num, hrclaimer); 387 } 388 389 G1TriggerClosure::G1TriggerClosure() : 390 _triggered(false) { } 391 392 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl, 393 OopClosure* oop_cl) : 394 _trigger_cl(t_cl), _oop_cl(oop_cl) { } 395 396 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) : 397 _c1(c1), _c2(c2) { } 398 399 G1UpdateRSOrPushRefOopClosure:: 400 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h, 401 G1RemSet* rs, 402 G1ParPushHeapRSClosure* push_ref_cl, 403 bool record_refs_into_cset, 404 uint worker_i) : 405 _g1(g1h), _g1_rem_set(rs), _from(NULL), 406 _record_refs_into_cset(record_refs_into_cset), 407 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { } 408 409 // Returns true if the given card contains references that point 410 // into the collection set, if we're checking for such references; 411 // false otherwise. 412 413 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i, 414 bool check_for_refs_into_cset) { 415 assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)), 416 "Card at " PTR_FORMAT " index " SIZE_FORMAT " representing heap at " PTR_FORMAT " (%u) must be in committed heap", 417 p2i(card_ptr), 418 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)), 419 p2i(_ct_bs->addr_for(card_ptr)), 420 _g1->addr_to_region(_ct_bs->addr_for(card_ptr))); 421 422 // If the card is no longer dirty, nothing to do. 423 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 424 // No need to return that this card contains refs that point 425 // into the collection set. 426 return false; 427 } 428 429 // Construct the region representing the card. 430 HeapWord* start = _ct_bs->addr_for(card_ptr); 431 // And find the region containing it. 432 HeapRegion* r = _g1->heap_region_containing(start); 433 434 // Why do we have to check here whether a card is on a young region, 435 // given that we dirty young regions and, as a result, the 436 // post-barrier is supposed to filter them out and never to enqueue 437 // them? When we allocate a new region as the "allocation region" we 438 // actually dirty its cards after we release the lock, since card 439 // dirtying while holding the lock was a performance bottleneck. So, 440 // as a result, it is possible for other threads to actually 441 // allocate objects in the region (after the acquire the lock) 442 // before all the cards on the region are dirtied. This is unlikely, 443 // and it doesn't happen often, but it can happen. So, the extra 444 // check below filters out those cards. 445 if (r->is_young()) { 446 return false; 447 } 448 449 // While we are processing RSet buffers during the collection, we 450 // actually don't want to scan any cards on the collection set, 451 // since we don't want to update remembered sets with entries that 452 // point into the collection set, given that live objects from the 453 // collection set are about to move and such entries will be stale 454 // very soon. This change also deals with a reliability issue which 455 // involves scanning a card in the collection set and coming across 456 // an array that was being chunked and looking malformed. Note, 457 // however, that if evacuation fails, we have to scan any objects 458 // that were not moved and create any missing entries. 459 if (r->in_collection_set()) { 460 return false; 461 } 462 463 // The result from the hot card cache insert call is either: 464 // * pointer to the current card 465 // (implying that the current card is not 'hot'), 466 // * null 467 // (meaning we had inserted the card ptr into the "hot" card cache, 468 // which had some headroom), 469 // * a pointer to a "hot" card that was evicted from the "hot" cache. 470 // 471 472 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 473 if (hot_card_cache->use_cache()) { 474 assert(!check_for_refs_into_cset, "sanity"); 475 assert(!SafepointSynchronize::is_at_safepoint(), "sanity"); 476 477 card_ptr = hot_card_cache->insert(card_ptr); 478 if (card_ptr == NULL) { 479 // There was no eviction. Nothing to do. 480 return false; 481 } 482 483 start = _ct_bs->addr_for(card_ptr); 484 r = _g1->heap_region_containing(start); 485 486 // Checking whether the region we got back from the cache 487 // is young here is inappropriate. The region could have been 488 // freed, reallocated and tagged as young while in the cache. 489 // Hence we could see its young type change at any time. 490 } 491 492 // Don't use addr_for(card_ptr + 1) which can ask for 493 // a card beyond the heap. This is not safe without a perm 494 // gen at the upper end of the heap. 495 HeapWord* end = start + CardTableModRefBS::card_size_in_words; 496 MemRegion dirtyRegion(start, end); 497 498 #if CARD_REPEAT_HISTO 499 init_ct_freq_table(_g1->max_capacity()); 500 ct_freq_note_card(_ct_bs->index_for(start)); 501 #endif 502 503 G1ParPushHeapRSClosure* oops_in_heap_closure = NULL; 504 if (check_for_refs_into_cset) { 505 // ConcurrentG1RefineThreads have worker numbers larger than what 506 // _cset_rs_update_cl[] is set up to handle. But those threads should 507 // only be active outside of a collection which means that when they 508 // reach here they should have check_for_refs_into_cset == false. 509 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length"); 510 oops_in_heap_closure = _cset_rs_update_cl[worker_i]; 511 } 512 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1, 513 _g1->g1_rem_set(), 514 oops_in_heap_closure, 515 check_for_refs_into_cset, 516 worker_i); 517 update_rs_oop_cl.set_from(r); 518 519 G1TriggerClosure trigger_cl; 520 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl); 521 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl); 522 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl); 523 524 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r, 525 (check_for_refs_into_cset ? 526 (OopClosure*)&mux : 527 (OopClosure*)&update_rs_oop_cl)); 528 529 // The region for the current card may be a young region. The 530 // current card may have been a card that was evicted from the 531 // card cache. When the card was inserted into the cache, we had 532 // determined that its region was non-young. While in the cache, 533 // the region may have been freed during a cleanup pause, reallocated 534 // and tagged as young. 535 // 536 // We wish to filter out cards for such a region but the current 537 // thread, if we're running concurrently, may "see" the young type 538 // change at any time (so an earlier "is_young" check may pass or 539 // fail arbitrarily). We tell the iteration code to perform this 540 // filtering when it has been determined that there has been an actual 541 // allocation in this region and making it safe to check the young type. 542 bool filter_young = true; 543 544 HeapWord* stop_point = 545 r->oops_on_card_seq_iterate_careful(dirtyRegion, 546 &filter_then_update_rs_oop_cl, 547 filter_young, 548 card_ptr); 549 550 // If stop_point is non-null, then we encountered an unallocated region 551 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the 552 // card and re-enqueue: if we put off the card until a GC pause, then the 553 // unallocated portion will be filled in. Alternatively, we might try 554 // the full complexity of the technique used in "regular" precleaning. 555 if (stop_point != NULL) { 556 // The card might have gotten re-dirtied and re-enqueued while we 557 // worked. (In fact, it's pretty likely.) 558 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 559 *card_ptr = CardTableModRefBS::dirty_card_val(); 560 MutexLockerEx x(Shared_DirtyCardQ_lock, 561 Mutex::_no_safepoint_check_flag); 562 DirtyCardQueue* sdcq = 563 JavaThread::dirty_card_queue_set().shared_dirty_card_queue(); 564 sdcq->enqueue(card_ptr); 565 } 566 } else { 567 _conc_refine_cards++; 568 } 569 570 // This gets set to true if the card being refined has 571 // references that point into the collection set. 572 bool has_refs_into_cset = trigger_cl.triggered(); 573 574 // We should only be detecting that the card contains references 575 // that point into the collection set if the current thread is 576 // a GC worker thread. 577 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(), 578 "invalid result at non safepoint"); 579 580 return has_refs_into_cset; 581 } 582 583 void G1RemSet::print_periodic_summary_info(const char* header) { 584 G1RemSetSummary current; 585 current.initialize(this); 586 587 _prev_period_summary.subtract_from(¤t); 588 print_summary_info(&_prev_period_summary, header); 589 590 _prev_period_summary.set(¤t); 591 } 592 593 void G1RemSet::print_summary_info() { 594 G1RemSetSummary current; 595 current.initialize(this); 596 597 print_summary_info(¤t, " Cumulative RS summary"); 598 } 599 600 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) { 601 assert(summary != NULL, "just checking"); 602 603 if (header != NULL) { 604 gclog_or_tty->print_cr("%s", header); 605 } 606 607 #if CARD_REPEAT_HISTO 608 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: "); 609 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number."); 610 card_repeat_count.print_on(gclog_or_tty); 611 #endif 612 613 summary->print_on(gclog_or_tty); 614 } 615 616 void G1RemSet::prepare_for_verify() { 617 if (G1HRRSFlushLogBuffersOnVerify && 618 (VerifyBeforeGC || VerifyAfterGC) 619 && (!_g1->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC)) { 620 cleanupHRRS(); 621 _g1->set_refine_cte_cl_concurrency(false); 622 if (SafepointSynchronize::is_at_safepoint()) { 623 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 624 dcqs.concatenate_logs(); 625 } 626 627 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 628 bool use_hot_card_cache = hot_card_cache->use_cache(); 629 hot_card_cache->set_use_cache(false); 630 631 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 632 updateRS(&into_cset_dcq, 0); 633 _g1->into_cset_dirty_card_queue_set().clear(); 634 635 hot_card_cache->set_use_cache(use_hot_card_cache); 636 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 637 } 638 }