1 /* 2 * Copyright (c) 2001, 2013, 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/bufferingOopClosure.hpp" 27 #include "gc_implementation/g1/concurrentG1Refine.hpp" 28 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 29 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp" 30 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 31 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 32 #include "gc_implementation/g1/g1HotCardCache.hpp" 33 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 34 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 35 #include "gc_implementation/g1/g1RemSet.inline.hpp" 36 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 37 #include "memory/iterator.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "utilities/intHisto.hpp" 40 41 #define CARD_REPEAT_HISTO 0 42 43 #if CARD_REPEAT_HISTO 44 static size_t ct_freq_sz; 45 static jbyte* ct_freq = NULL; 46 47 void init_ct_freq_table(size_t heap_sz_bytes) { 48 if (ct_freq == NULL) { 49 ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size; 50 ct_freq = new jbyte[ct_freq_sz]; 51 for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0; 52 } 53 } 54 55 void ct_freq_note_card(size_t index) { 56 assert(0 <= index && index < ct_freq_sz, "Bounds error."); 57 if (ct_freq[index] < 100) { ct_freq[index]++; } 58 } 59 60 static IntHistogram card_repeat_count(10, 10); 61 62 void ct_freq_update_histo_and_reset() { 63 for (size_t j = 0; j < ct_freq_sz; j++) { 64 card_repeat_count.add_entry(ct_freq[j]); 65 ct_freq[j] = 0; 66 } 67 68 } 69 #endif 70 71 G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs) 72 : _g1(g1), _conc_refine_cards(0), 73 _ct_bs(ct_bs), _g1p(_g1->g1_policy()), 74 _cg1r(g1->concurrent_g1_refine()), 75 _cset_rs_update_cl(NULL), 76 _cards_scanned(NULL), _total_cards_scanned(0) 77 { 78 _seq_task = new SubTasksDone(NumSeqTasks); 79 guarantee(n_workers() > 0, "There should be some workers"); 80 _cset_rs_update_cl = NEW_C_HEAP_ARRAY(OopsInHeapRegionClosure*, n_workers(), mtGC); 81 for (uint i = 0; i < n_workers(); i++) { 82 _cset_rs_update_cl[i] = NULL; 83 } 84 } 85 86 G1RemSet::~G1RemSet() { 87 delete _seq_task; 88 for (uint i = 0; i < n_workers(); i++) { 89 assert(_cset_rs_update_cl[i] == NULL, "it should be"); 90 } 91 FREE_C_HEAP_ARRAY(OopsInHeapRegionClosure*, _cset_rs_update_cl, mtGC); 92 } 93 94 void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) { 95 if (_g1->is_in_g1_reserved(mr.start())) { 96 _n += (int) ((mr.byte_size() / CardTableModRefBS::card_size)); 97 if (_start_first == NULL) _start_first = mr.start(); 98 } 99 } 100 101 class ScanRSClosure : public HeapRegionClosure { 102 size_t _cards_done, _cards; 103 G1CollectedHeap* _g1h; 104 OopsInHeapRegionClosure* _oc; 105 G1BlockOffsetSharedArray* _bot_shared; 106 CardTableModRefBS *_ct_bs; 107 int _worker_i; 108 int _block_size; 109 bool _try_claimed; 110 public: 111 ScanRSClosure(OopsInHeapRegionClosure* oc, int worker_i) : 112 _oc(oc), 113 _cards(0), 114 _cards_done(0), 115 _worker_i(worker_i), 116 _try_claimed(false) 117 { 118 _g1h = G1CollectedHeap::heap(); 119 _bot_shared = _g1h->bot_shared(); 120 _ct_bs = (CardTableModRefBS*) (_g1h->barrier_set()); 121 _block_size = MAX2<int>(G1RSetScanBlockSize, 1); 122 } 123 124 void set_try_claimed() { _try_claimed = true; } 125 126 void scanCard(size_t index, HeapRegion *r) { 127 // Stack allocate the DirtyCardToOopClosure instance 128 HeapRegionDCTOC cl(_g1h, r, _oc, 129 CardTableModRefBS::Precise, 130 HeapRegionDCTOC::IntoCSFilterKind); 131 132 // Set the "from" region in the closure. 133 _oc->set_region(r); 134 HeapWord* card_start = _bot_shared->address_for_index(index); 135 HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words; 136 Space *sp = SharedHeap::heap()->space_containing(card_start); 137 MemRegion sm_region = sp->used_region_at_save_marks(); 138 MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end)); 139 if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) { 140 // We make the card as "claimed" lazily (so races are possible 141 // but they're benign), which reduces the number of duplicate 142 // scans (the rsets of the regions in the cset can intersect). 143 _ct_bs->set_card_claimed(index); 144 _cards_done++; 145 cl.do_MemRegion(mr); 146 } 147 } 148 149 void printCard(HeapRegion* card_region, size_t card_index, 150 HeapWord* card_start) { 151 gclog_or_tty->print_cr("T %d Region [" PTR_FORMAT ", " PTR_FORMAT ") " 152 "RS names card %p: " 153 "[" PTR_FORMAT ", " PTR_FORMAT ")", 154 _worker_i, 155 card_region->bottom(), card_region->end(), 156 card_index, 157 card_start, card_start + G1BlockOffsetSharedArray::N_words); 158 } 159 160 bool doHeapRegion(HeapRegion* r) { 161 assert(r->in_collection_set(), "should only be called on elements of CS."); 162 HeapRegionRemSet* hrrs = r->rem_set(); 163 if (hrrs->iter_is_complete()) return false; // All done. 164 if (!_try_claimed && !hrrs->claim_iter()) return false; 165 // If we ever free the collection set concurrently, we should also 166 // clear the card table concurrently therefore we won't need to 167 // add regions of the collection set to the dirty cards region. 168 _g1h->push_dirty_cards_region(r); 169 // If we didn't return above, then 170 // _try_claimed || r->claim_iter() 171 // is true: either we're supposed to work on claimed-but-not-complete 172 // regions, or we successfully claimed the region. 173 HeapRegionRemSetIterator* iter = _g1h->rem_set_iterator(_worker_i); 174 hrrs->init_iterator(iter); 175 size_t card_index; 176 177 // We claim cards in block so as to recude the contention. The block size is determined by 178 // the G1RSetScanBlockSize parameter. 179 size_t jump_to_card = hrrs->iter_claimed_next(_block_size); 180 for (size_t current_card = 0; iter->has_next(card_index); current_card++) { 181 if (current_card >= jump_to_card + _block_size) { 182 jump_to_card = hrrs->iter_claimed_next(_block_size); 183 } 184 if (current_card < jump_to_card) continue; 185 HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index); 186 #if 0 187 gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n", 188 card_start, card_start + CardTableModRefBS::card_size_in_words); 189 #endif 190 191 HeapRegion* card_region = _g1h->heap_region_containing(card_start); 192 assert(card_region != NULL, "Yielding cards not in the heap?"); 193 _cards++; 194 195 if (!card_region->is_on_dirty_cards_region_list()) { 196 _g1h->push_dirty_cards_region(card_region); 197 } 198 199 // If the card is dirty, then we will scan it during updateRS. 200 if (!card_region->in_collection_set() && 201 !_ct_bs->is_card_dirty(card_index)) { 202 scanCard(card_index, card_region); 203 } 204 } 205 if (!_try_claimed) { 206 hrrs->set_iter_complete(); 207 } 208 return false; 209 } 210 size_t cards_done() { return _cards_done;} 211 size_t cards_looked_up() { return _cards;} 212 }; 213 214 void G1RemSet::scanRS(OopsInHeapRegionClosure* oc, int worker_i) { 215 double rs_time_start = os::elapsedTime(); 216 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i); 217 218 ScanRSClosure scanRScl(oc, worker_i); 219 220 _g1->collection_set_iterate_from(startRegion, &scanRScl); 221 scanRScl.set_try_claimed(); 222 _g1->collection_set_iterate_from(startRegion, &scanRScl); 223 224 double scan_rs_time_sec = os::elapsedTime() - rs_time_start; 225 226 assert( _cards_scanned != NULL, "invariant" ); 227 _cards_scanned[worker_i] = scanRScl.cards_done(); 228 229 _g1p->phase_times()->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0); 230 } 231 232 // Closure used for updating RSets and recording references that 233 // point into the collection set. Only called during an 234 // evacuation pause. 235 236 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure { 237 G1RemSet* _g1rs; 238 DirtyCardQueue* _into_cset_dcq; 239 public: 240 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h, 241 DirtyCardQueue* into_cset_dcq) : 242 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq) 243 {} 244 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 245 // The only time we care about recording cards that 246 // contain references that point into the collection set 247 // is during RSet updating within an evacuation pause. 248 // In this case worker_i should be the id of a GC worker thread. 249 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause"); 250 assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker"); 251 252 if (_g1rs->refine_card(card_ptr, worker_i, true)) { 253 // 'card_ptr' contains references that point into the collection 254 // set. We need to record the card in the DCQS 255 // (G1CollectedHeap::into_cset_dirty_card_queue_set()) 256 // that's used for that purpose. 257 // 258 // Enqueue the card 259 _into_cset_dcq->enqueue(card_ptr); 260 } 261 return true; 262 } 263 }; 264 265 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) { 266 double start = os::elapsedTime(); 267 // Apply the given closure to all remaining log entries. 268 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq); 269 270 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i); 271 272 // Now there should be no dirty cards. 273 if (G1RSLogCheckCardTable) { 274 CountNonCleanMemRegionClosure cl(_g1); 275 _ct_bs->mod_card_iterate(&cl); 276 // XXX This isn't true any more: keeping cards of young regions 277 // marked dirty broke it. Need some reasonable fix. 278 guarantee(cl.n() == 0, "Card table should be clean."); 279 } 280 281 _g1p->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0); 282 } 283 284 void G1RemSet::cleanupHRRS() { 285 HeapRegionRemSet::cleanup(); 286 } 287 288 void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc, 289 int worker_i) { 290 #if CARD_REPEAT_HISTO 291 ct_freq_update_histo_and_reset(); 292 #endif 293 294 // We cache the value of 'oc' closure into the appropriate slot in the 295 // _cset_rs_update_cl for this worker 296 assert(worker_i < (int)n_workers(), "sanity"); 297 _cset_rs_update_cl[worker_i] = oc; 298 299 // A DirtyCardQueue that is used to hold cards containing references 300 // that point into the collection set. This DCQ is associated with a 301 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal 302 // circumstances (i.e. the pause successfully completes), these cards 303 // are just discarded (there's no need to update the RSets of regions 304 // that were in the collection set - after the pause these regions 305 // are wholly 'free' of live objects. In the event of an evacuation 306 // failure the cards/buffers in this queue set are: 307 // * passed to the DirtyCardQueueSet that is used to manage deferred 308 // RSet updates, or 309 // * scanned for references that point into the collection set 310 // and the RSet of the corresponding region in the collection set 311 // is updated immediately. 312 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 313 314 assert((ParallelGCThreads > 0) || worker_i == 0, "invariant"); 315 316 // The two flags below were introduced temporarily to serialize 317 // the updating and scanning of remembered sets. There are some 318 // race conditions when these two operations are done in parallel 319 // and they are causing failures. When we resolve said race 320 // conditions, we'll revert back to parallel remembered set 321 // updating and scanning. See CRs 6677707 and 6677708. 322 if (G1UseParallelRSetUpdating || (worker_i == 0)) { 323 updateRS(&into_cset_dcq, worker_i); 324 } else { 325 _g1p->phase_times()->record_update_rs_processed_buffers(worker_i, 0); 326 _g1p->phase_times()->record_update_rs_time(worker_i, 0.0); 327 } 328 if (G1UseParallelRSetScanning || (worker_i == 0)) { 329 scanRS(oc, worker_i); 330 } else { 331 _g1p->phase_times()->record_scan_rs_time(worker_i, 0.0); 332 } 333 334 // We now clear the cached values of _cset_rs_update_cl for this worker 335 _cset_rs_update_cl[worker_i] = NULL; 336 } 337 338 void G1RemSet::prepare_for_oops_into_collection_set_do() { 339 cleanupHRRS(); 340 ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine(); 341 _g1->set_refine_cte_cl_concurrency(false); 342 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 343 dcqs.concatenate_logs(); 344 345 if (G1CollectedHeap::use_parallel_gc_threads()) { 346 // Don't set the number of workers here. It will be set 347 // when the task is run 348 // _seq_task->set_n_termination((int)n_workers()); 349 } 350 guarantee( _cards_scanned == NULL, "invariant" ); 351 _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC); 352 for (uint i = 0; i < n_workers(); ++i) { 353 _cards_scanned[i] = 0; 354 } 355 _total_cards_scanned = 0; 356 } 357 358 359 // This closure, applied to a DirtyCardQueueSet, is used to immediately 360 // update the RSets for the regions in the CSet. For each card it iterates 361 // through the oops which coincide with that card. It scans the reference 362 // fields in each oop; when it finds an oop that points into the collection 363 // set, the RSet for the region containing the referenced object is updated. 364 class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure { 365 G1CollectedHeap* _g1; 366 CardTableModRefBS* _ct_bs; 367 public: 368 UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1, 369 CardTableModRefBS* bs): 370 _g1(g1), _ct_bs(bs) 371 { } 372 373 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 374 // Construct the region representing the card. 375 HeapWord* start = _ct_bs->addr_for(card_ptr); 376 // And find the region containing it. 377 HeapRegion* r = _g1->heap_region_containing(start); 378 assert(r != NULL, "unexpected null"); 379 380 // Scan oops in the card looking for references into the collection set 381 // Don't use addr_for(card_ptr + 1) which can ask for 382 // a card beyond the heap. This is not safe without a perm 383 // gen. 384 HeapWord* end = start + CardTableModRefBS::card_size_in_words; 385 MemRegion scanRegion(start, end); 386 387 UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set()); 388 FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl); 389 FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl); 390 391 // We can pass false as the "filter_young" parameter here as: 392 // * we should be in a STW pause, 393 // * the DCQS to which this closure is applied is used to hold 394 // references that point into the collection set from the prior 395 // RSet updating, 396 // * the post-write barrier shouldn't be logging updates to young 397 // regions (but there is a situation where this can happen - see 398 // the comment in G1RemSet::refine_card() below - 399 // that should not be applicable here), and 400 // * during actual RSet updating, the filtering of cards in young 401 // regions in HeapRegion::oops_on_card_seq_iterate_careful is 402 // employed. 403 // As a result, when this closure is applied to "refs into cset" 404 // DCQS, we shouldn't see any cards in young regions. 405 update_rs_cl.set_region(r); 406 HeapWord* stop_point = 407 r->oops_on_card_seq_iterate_careful(scanRegion, 408 &filter_then_update_rs_cset_oop_cl, 409 false /* filter_young */, 410 NULL /* card_ptr */); 411 412 // Since this is performed in the event of an evacuation failure, we 413 // we shouldn't see a non-null stop point 414 assert(stop_point == NULL, "saw an unallocated region"); 415 return true; 416 } 417 }; 418 419 void G1RemSet::cleanup_after_oops_into_collection_set_do() { 420 guarantee( _cards_scanned != NULL, "invariant" ); 421 _total_cards_scanned = 0; 422 for (uint i = 0; i < n_workers(); ++i) { 423 _total_cards_scanned += _cards_scanned[i]; 424 } 425 FREE_C_HEAP_ARRAY(size_t, _cards_scanned, mtGC); 426 _cards_scanned = NULL; 427 // Cleanup after copy 428 _g1->set_refine_cte_cl_concurrency(true); 429 // Set all cards back to clean. 430 _g1->cleanUpCardTable(); 431 432 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set(); 433 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num(); 434 435 if (_g1->evacuation_failed()) { 436 // Restore remembered sets for the regions pointing into the collection set. 437 438 if (G1DeferredRSUpdate) { 439 // If deferred RS updates are enabled then we just need to transfer 440 // the completed buffers from (a) the DirtyCardQueueSet used to hold 441 // cards that contain references that point into the collection set 442 // to (b) the DCQS used to hold the deferred RS updates 443 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs); 444 } else { 445 446 CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set(); 447 UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs); 448 449 int n_completed_buffers = 0; 450 while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate, 451 0, 0, true)) { 452 n_completed_buffers++; 453 } 454 assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers"); 455 } 456 } 457 458 // Free any completed buffers in the DirtyCardQueueSet used to hold cards 459 // which contain references that point into the collection. 460 _g1->into_cset_dirty_card_queue_set().clear(); 461 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0, 462 "all buffers should be freed"); 463 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers(); 464 } 465 466 class ScrubRSClosure: public HeapRegionClosure { 467 G1CollectedHeap* _g1h; 468 BitMap* _region_bm; 469 BitMap* _card_bm; 470 CardTableModRefBS* _ctbs; 471 public: 472 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) : 473 _g1h(G1CollectedHeap::heap()), 474 _region_bm(region_bm), _card_bm(card_bm), 475 _ctbs(NULL) 476 { 477 ModRefBarrierSet* bs = _g1h->mr_bs(); 478 guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition"); 479 _ctbs = (CardTableModRefBS*)bs; 480 } 481 482 bool doHeapRegion(HeapRegion* r) { 483 if (!r->continuesHumongous()) { 484 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm); 485 } 486 return false; 487 } 488 }; 489 490 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) { 491 ScrubRSClosure scrub_cl(region_bm, card_bm); 492 _g1->heap_region_iterate(&scrub_cl); 493 } 494 495 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm, 496 uint worker_num, int claim_val) { 497 ScrubRSClosure scrub_cl(region_bm, card_bm); 498 _g1->heap_region_par_iterate_chunked(&scrub_cl, 499 worker_num, 500 n_workers(), 501 claim_val); 502 } 503 504 G1TriggerClosure::G1TriggerClosure() : 505 _triggered(false) { } 506 507 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl, 508 OopClosure* oop_cl) : 509 _trigger_cl(t_cl), _oop_cl(oop_cl) { } 510 511 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) : 512 _c1(c1), _c2(c2) { } 513 514 G1UpdateRSOrPushRefOopClosure:: 515 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h, 516 G1RemSet* rs, 517 OopsInHeapRegionClosure* push_ref_cl, 518 bool record_refs_into_cset, 519 int worker_i) : 520 _g1(g1h), _g1_rem_set(rs), _from(NULL), 521 _record_refs_into_cset(record_refs_into_cset), 522 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { } 523 524 525 bool G1RemSet::refine_card_helper(jbyte* card_ptr, int worker_i, 526 bool check_for_refs_into_cset) { 527 // Returns true if the given card contains references that point 528 // into the collection set, if we're checking for such references; 529 // false otherwise. 530 531 // Construct the region representing the card. 532 HeapWord* start = _ct_bs->addr_for(card_ptr); 533 // And find the region containing it. 534 HeapRegion* r = _g1->heap_region_containing(start); 535 assert(r != NULL, "unexpected null"); 536 537 // Don't use addr_for(card_ptr + 1) which can ask for 538 // a card beyond the heap. This is not safe without a perm 539 // gen at the upper end of the heap. 540 HeapWord* end = start + CardTableModRefBS::card_size_in_words; 541 MemRegion dirtyRegion(start, end); 542 543 #if CARD_REPEAT_HISTO 544 init_ct_freq_table(_g1->max_capacity()); 545 ct_freq_note_card(_ct_bs->index_for(start)); 546 #endif 547 548 OopsInHeapRegionClosure* oops_in_heap_closure = NULL; 549 if (check_for_refs_into_cset) { 550 // ConcurrentG1RefineThreads have worker numbers larger than what 551 // _cset_rs_update_cl[] is set up to handle. But those threads should 552 // only be active outside of a collection which means that when they 553 // reach here they should have check_for_refs_into_cset == false. 554 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length"); 555 oops_in_heap_closure = _cset_rs_update_cl[worker_i]; 556 } 557 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1, 558 _g1->g1_rem_set(), 559 oops_in_heap_closure, 560 check_for_refs_into_cset, 561 worker_i); 562 update_rs_oop_cl.set_from(r); 563 564 G1TriggerClosure trigger_cl; 565 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl); 566 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl); 567 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl); 568 569 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r, 570 (check_for_refs_into_cset ? 571 (OopClosure*)&mux : 572 (OopClosure*)&update_rs_oop_cl)); 573 574 // The region for the current card may be a young region. The 575 // current card may have been a card that was evicted from the 576 // card cache. When the card was inserted into the cache, we had 577 // determined that its region was non-young. While in the cache, 578 // the region may have been freed during a cleanup pause, reallocated 579 // and tagged as young. 580 // 581 // We wish to filter out cards for such a region but the current 582 // thread, if we're running concurrently, may "see" the young type 583 // change at any time (so an earlier "is_young" check may pass or 584 // fail arbitrarily). We tell the iteration code to perform this 585 // filtering when it has been determined that there has been an actual 586 // allocation in this region and making it safe to check the young type. 587 bool filter_young = true; 588 589 HeapWord* stop_point = 590 r->oops_on_card_seq_iterate_careful(dirtyRegion, 591 &filter_then_update_rs_oop_cl, 592 filter_young, 593 card_ptr); 594 595 // If stop_point is non-null, then we encountered an unallocated region 596 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the 597 // card and re-enqueue: if we put off the card until a GC pause, then the 598 // unallocated portion will be filled in. Alternatively, we might try 599 // the full complexity of the technique used in "regular" precleaning. 600 if (stop_point != NULL) { 601 // The card might have gotten re-dirtied and re-enqueued while we 602 // worked. (In fact, it's pretty likely.) 603 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 604 *card_ptr = CardTableModRefBS::dirty_card_val(); 605 MutexLockerEx x(Shared_DirtyCardQ_lock, 606 Mutex::_no_safepoint_check_flag); 607 DirtyCardQueue* sdcq = 608 JavaThread::dirty_card_queue_set().shared_dirty_card_queue(); 609 sdcq->enqueue(card_ptr); 610 } 611 } else { 612 _conc_refine_cards++; 613 } 614 615 return trigger_cl.triggered(); 616 } 617 618 bool G1RemSet::refine_card(jbyte* card_ptr, int worker_i, 619 bool check_for_refs_into_cset) { 620 621 // If the card is no longer dirty, nothing to do. 622 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 623 // No need to return that this card contains refs that point 624 // into the collection set. 625 return false; 626 } 627 628 // Construct the region representing the card. 629 HeapWord* start = _ct_bs->addr_for(card_ptr); 630 // And find the region containing it. 631 HeapRegion* r = _g1->heap_region_containing(start); 632 if (r == NULL) { 633 // Again no need to return that this card contains refs that 634 // point into the collection set. 635 return false; // Not in the G1 heap (might be in perm, for example.) 636 } 637 638 // Why do we have to check here whether a card is on a young region, 639 // given that we dirty young regions and, as a result, the 640 // post-barrier is supposed to filter them out and never to enqueue 641 // them? When we allocate a new region as the "allocation region" we 642 // actually dirty its cards after we release the lock, since card 643 // dirtying while holding the lock was a performance bottleneck. So, 644 // as a result, it is possible for other threads to actually 645 // allocate objects in the region (after the acquire the lock) 646 // before all the cards on the region are dirtied. This is unlikely, 647 // and it doesn't happen often, but it can happen. So, the extra 648 // check below filters out those cards. 649 if (r->is_young()) { 650 return false; 651 } 652 653 // While we are processing RSet buffers during the collection, we 654 // actually don't want to scan any cards on the collection set, 655 // since we don't want to update remebered sets with entries that 656 // point into the collection set, given that live objects from the 657 // collection set are about to move and such entries will be stale 658 // very soon. This change also deals with a reliability issue which 659 // involves scanning a card in the collection set and coming across 660 // an array that was being chunked and looking malformed. Note, 661 // however, that if evacuation fails, we have to scan any objects 662 // that were not moved and create any missing entries. 663 if (r->in_collection_set()) { 664 return false; 665 } 666 667 // The result from the hot card cache insert call is either: 668 // * pointer to the current card 669 // (implying that the current card is not 'hot'), 670 // * null 671 // (meaning we had inserted the card ptr into the "hot" card cache, 672 // which had some headroom), 673 // * a pointer to a "hot" card that was evicted from the "hot" cache. 674 // 675 676 // This gets set to true if the card being refined has 677 // references that point into the collection set. 678 bool has_refs_into_cset = false; 679 680 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 681 if (hot_card_cache->use_cache()) { 682 assert(!check_for_refs_into_cset, "sanity"); 683 assert(!SafepointSynchronize::is_at_safepoint(), "sanity"); 684 685 card_ptr = hot_card_cache->insert(card_ptr); 686 if (card_ptr == NULL) { 687 // There was no eviction. Nothing to do. 688 return has_refs_into_cset; 689 } 690 691 start = _ct_bs->addr_for(card_ptr); 692 r = _g1->heap_region_containing(start); 693 if (r == NULL) { 694 // Not in the G1 heap 695 return has_refs_into_cset; 696 } 697 698 // Checking whether the region we got back from the cache 699 // is young here is inappropriate. The region could have been 700 // freed, reallocated and tagged as young while in the cache. 701 // Hence we could see its young type change at any time. 702 } 703 704 has_refs_into_cset = refine_card_helper(card_ptr, worker_i, 705 check_for_refs_into_cset); 706 // We should only be detecting that the card contains references 707 // that point into the collection set if the current thread is 708 // a GC worker thread. 709 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(), 710 "invalid result at non safepoint"); 711 712 return has_refs_into_cset; 713 } 714 715 class HRRSStatsIter: public HeapRegionClosure { 716 size_t _occupied; 717 size_t _total_mem_sz; 718 size_t _max_mem_sz; 719 HeapRegion* _max_mem_sz_region; 720 public: 721 HRRSStatsIter() : 722 _occupied(0), 723 _total_mem_sz(0), 724 _max_mem_sz(0), 725 _max_mem_sz_region(NULL) 726 {} 727 728 bool doHeapRegion(HeapRegion* r) { 729 if (r->continuesHumongous()) return false; 730 size_t mem_sz = r->rem_set()->mem_size(); 731 if (mem_sz > _max_mem_sz) { 732 _max_mem_sz = mem_sz; 733 _max_mem_sz_region = r; 734 } 735 _total_mem_sz += mem_sz; 736 size_t occ = r->rem_set()->occupied(); 737 _occupied += occ; 738 return false; 739 } 740 size_t total_mem_sz() { return _total_mem_sz; } 741 size_t max_mem_sz() { return _max_mem_sz; } 742 size_t occupied() { return _occupied; } 743 HeapRegion* max_mem_sz_region() { return _max_mem_sz_region; } 744 }; 745 746 class PrintRSThreadVTimeClosure : public ThreadClosure { 747 public: 748 virtual void do_thread(Thread *t) { 749 ConcurrentG1RefineThread* crt = (ConcurrentG1RefineThread*) t; 750 gclog_or_tty->print(" %5.2f", crt->vtime_accum()); 751 } 752 }; 753 754 void G1RemSet::print_summary_info() { 755 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 756 757 #if CARD_REPEAT_HISTO 758 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: "); 759 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number."); 760 card_repeat_count.print_on(gclog_or_tty); 761 #endif 762 763 gclog_or_tty->print_cr("\n Concurrent RS processed %d cards", 764 _conc_refine_cards); 765 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 766 jint tot_processed_buffers = 767 dcqs.processed_buffers_mut() + dcqs.processed_buffers_rs_thread(); 768 gclog_or_tty->print_cr(" Of %d completed buffers:", tot_processed_buffers); 769 gclog_or_tty->print_cr(" %8d (%5.1f%%) by conc RS threads.", 770 dcqs.processed_buffers_rs_thread(), 771 100.0*(float)dcqs.processed_buffers_rs_thread()/ 772 (float)tot_processed_buffers); 773 gclog_or_tty->print_cr(" %8d (%5.1f%%) by mutator threads.", 774 dcqs.processed_buffers_mut(), 775 100.0*(float)dcqs.processed_buffers_mut()/ 776 (float)tot_processed_buffers); 777 gclog_or_tty->print_cr(" Conc RS threads times(s)"); 778 PrintRSThreadVTimeClosure p; 779 gclog_or_tty->print(" "); 780 g1->concurrent_g1_refine()->threads_do(&p); 781 gclog_or_tty->print_cr(""); 782 783 HRRSStatsIter blk; 784 g1->heap_region_iterate(&blk); 785 gclog_or_tty->print_cr(" Total heap region rem set sizes = "SIZE_FORMAT"K." 786 " Max = "SIZE_FORMAT"K.", 787 blk.total_mem_sz()/K, blk.max_mem_sz()/K); 788 gclog_or_tty->print_cr(" Static structures = "SIZE_FORMAT"K," 789 " free_lists = "SIZE_FORMAT"K.", 790 HeapRegionRemSet::static_mem_size() / K, 791 HeapRegionRemSet::fl_mem_size() / K); 792 gclog_or_tty->print_cr(" "SIZE_FORMAT" occupied cards represented.", 793 blk.occupied()); 794 HeapRegion* max_mem_sz_region = blk.max_mem_sz_region(); 795 HeapRegionRemSet* rem_set = max_mem_sz_region->rem_set(); 796 gclog_or_tty->print_cr(" Max size region = "HR_FORMAT", " 797 "size = "SIZE_FORMAT "K, occupied = "SIZE_FORMAT"K.", 798 HR_FORMAT_PARAMS(max_mem_sz_region), 799 (rem_set->mem_size() + K - 1)/K, 800 (rem_set->occupied() + K - 1)/K); 801 gclog_or_tty->print_cr(" Did %d coarsenings.", 802 HeapRegionRemSet::n_coarsenings()); 803 } 804 805 void G1RemSet::prepare_for_verify() { 806 if (G1HRRSFlushLogBuffersOnVerify && 807 (VerifyBeforeGC || VerifyAfterGC) 808 && !_g1->full_collection()) { 809 cleanupHRRS(); 810 _g1->set_refine_cte_cl_concurrency(false); 811 if (SafepointSynchronize::is_at_safepoint()) { 812 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 813 dcqs.concatenate_logs(); 814 } 815 816 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 817 bool use_hot_card_cache = hot_card_cache->use_cache(); 818 hot_card_cache->set_use_cache(false); 819 820 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set()); 821 updateRS(&into_cset_dcq, 0); 822 _g1->into_cset_dirty_card_queue_set().clear(); 823 824 hot_card_cache->set_use_cache(use_hot_card_cache); 825 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 826 } 827 }