1 /*
2 * Copyright (c) 2001, 2012, 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/g1GCPhaseTimes.hpp"
33 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
34 #include "gc_implementation/g1/g1RemSet.inline.hpp"
35 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
36 #include "memory/iterator.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "utilities/intHisto.hpp"
39
40 #define CARD_REPEAT_HISTO 0
41
42 #if CARD_REPEAT_HISTO
43 static size_t ct_freq_sz;
44 static jbyte* ct_freq = NULL;
45
46 void init_ct_freq_table(size_t heap_sz_bytes) {
47 if (ct_freq == NULL) {
48 ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size;
49 ct_freq = new jbyte[ct_freq_sz];
50 for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0;
51 }
231 // Closure used for updating RSets and recording references that
232 // point into the collection set. Only called during an
233 // evacuation pause.
234
235 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
236 G1RemSet* _g1rs;
237 DirtyCardQueue* _into_cset_dcq;
238 public:
239 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
240 DirtyCardQueue* into_cset_dcq) :
241 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
242 {}
243 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
244 // The only time we care about recording cards that
245 // contain references that point into the collection set
246 // is during RSet updating within an evacuation pause.
247 // In this case worker_i should be the id of a GC worker thread.
248 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
249 assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
250
251 if (_g1rs->concurrentRefineOneCard(card_ptr, worker_i, true)) {
252 // 'card_ptr' contains references that point into the collection
253 // set. We need to record the card in the DCQS
254 // (G1CollectedHeap::into_cset_dirty_card_queue_set())
255 // that's used for that purpose.
256 //
257 // Enqueue the card
258 _into_cset_dcq->enqueue(card_ptr);
259 }
260 return true;
261 }
262 };
263
264 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) {
265 double start = os::elapsedTime();
266 // Apply the given closure to all remaining log entries.
267 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
268
269 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
270
271 // Now there should be no dirty cards.
272 if (G1RSLogCheckCardTable) {
273 CountNonCleanMemRegionClosure cl(_g1);
274 _ct_bs->mod_card_iterate(&cl);
275 // XXX This isn't true any more: keeping cards of young regions
276 // marked dirty broke it. Need some reasonable fix.
277 guarantee(cl.n() == 0, "Card table should be clean.");
278 }
279
280 _g1p->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
281 }
282
283 void G1RemSet::cleanupHRRS() {
284 HeapRegionRemSet::cleanup();
285 }
286
287 void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
288 int worker_i) {
289 #if CARD_REPEAT_HISTO
290 ct_freq_update_histo_and_reset();
291 #endif
292 if (worker_i == 0) {
293 _cg1r->clear_and_record_card_counts();
294 }
295
296 // We cache the value of 'oc' closure into the appropriate slot in the
297 // _cset_rs_update_cl for this worker
298 assert(worker_i < (int)n_workers(), "sanity");
299 _cset_rs_update_cl[worker_i] = oc;
300
301 // A DirtyCardQueue that is used to hold cards containing references
302 // that point into the collection set. This DCQ is associated with a
303 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
304 // circumstances (i.e. the pause successfully completes), these cards
305 // are just discarded (there's no need to update the RSets of regions
306 // that were in the collection set - after the pause these regions
307 // are wholly 'free' of live objects. In the event of an evacuation
308 // failure the cards/buffers in this queue set are:
309 // * passed to the DirtyCardQueueSet that is used to manage deferred
310 // RSet updates, or
311 // * scanned for references that point into the collection set
312 // and the RSet of the corresponding region in the collection set
313 // is updated immediately.
314 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
380 assert(r != NULL, "unexpected null");
381
382 // Scan oops in the card looking for references into the collection set
383 // Don't use addr_for(card_ptr + 1) which can ask for
384 // a card beyond the heap. This is not safe without a perm
385 // gen.
386 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
387 MemRegion scanRegion(start, end);
388
389 UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
390 FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
391 FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
392
393 // We can pass false as the "filter_young" parameter here as:
394 // * we should be in a STW pause,
395 // * the DCQS to which this closure is applied is used to hold
396 // references that point into the collection set from the prior
397 // RSet updating,
398 // * the post-write barrier shouldn't be logging updates to young
399 // regions (but there is a situation where this can happen - see
400 // the comment in G1RemSet::concurrentRefineOneCard below -
401 // that should not be applicable here), and
402 // * during actual RSet updating, the filtering of cards in young
403 // regions in HeapRegion::oops_on_card_seq_iterate_careful is
404 // employed.
405 // As a result, when this closure is applied to "refs into cset"
406 // DCQS, we shouldn't see any cards in young regions.
407 update_rs_cl.set_region(r);
408 HeapWord* stop_point =
409 r->oops_on_card_seq_iterate_careful(scanRegion,
410 &filter_then_update_rs_cset_oop_cl,
411 false /* filter_young */,
412 NULL /* card_ptr */);
413
414 // Since this is performed in the event of an evacuation failure, we
415 // we shouldn't see a non-null stop point
416 assert(stop_point == NULL, "saw an unallocated region");
417 return true;
418 }
419 };
420
486 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
487 }
488 return false;
489 }
490 };
491
492 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
493 ScrubRSClosure scrub_cl(region_bm, card_bm);
494 _g1->heap_region_iterate(&scrub_cl);
495 }
496
497 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
498 uint worker_num, int claim_val) {
499 ScrubRSClosure scrub_cl(region_bm, card_bm);
500 _g1->heap_region_par_iterate_chunked(&scrub_cl,
501 worker_num,
502 n_workers(),
503 claim_val);
504 }
505
506
507
508 G1TriggerClosure::G1TriggerClosure() :
509 _triggered(false) { }
510
511 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
512 OopClosure* oop_cl) :
513 _trigger_cl(t_cl), _oop_cl(oop_cl) { }
514
515 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
516 _c1(c1), _c2(c2) { }
517
518 G1UpdateRSOrPushRefOopClosure::
519 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
520 G1RemSet* rs,
521 OopsInHeapRegionClosure* push_ref_cl,
522 bool record_refs_into_cset,
523 int worker_i) :
524 _g1(g1h), _g1_rem_set(rs), _from(NULL),
525 _record_refs_into_cset(record_refs_into_cset),
526 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
527
528 bool G1RemSet::concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
529 bool check_for_refs_into_cset) {
530 // Construct the region representing the card.
531 HeapWord* start = _ct_bs->addr_for(card_ptr);
532 // And find the region containing it.
533 HeapRegion* r = _g1->heap_region_containing(start);
534 assert(r != NULL, "unexpected null");
535
536 // Don't use addr_for(card_ptr + 1) which can ask for
537 // a card beyond the heap. This is not safe without a perm
538 // gen at the upper end of the heap.
539 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
540 MemRegion dirtyRegion(start, end);
541
542 #if CARD_REPEAT_HISTO
543 init_ct_freq_table(_g1->max_capacity());
544 ct_freq_note_card(_ct_bs->index_for(start));
545 #endif
546
547 OopsInHeapRegionClosure* oops_in_heap_closure = NULL;
548 if (check_for_refs_into_cset) {
549 // ConcurrentG1RefineThreads have worker numbers larger than what
597 // unallocated portion will be filled in. Alternatively, we might try
598 // the full complexity of the technique used in "regular" precleaning.
599 if (stop_point != NULL) {
600 // The card might have gotten re-dirtied and re-enqueued while we
601 // worked. (In fact, it's pretty likely.)
602 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
603 *card_ptr = CardTableModRefBS::dirty_card_val();
604 MutexLockerEx x(Shared_DirtyCardQ_lock,
605 Mutex::_no_safepoint_check_flag);
606 DirtyCardQueue* sdcq =
607 JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
608 sdcq->enqueue(card_ptr);
609 }
610 } else {
611 _conc_refine_cards++;
612 }
613
614 return trigger_cl.triggered();
615 }
616
617 bool G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
618 bool check_for_refs_into_cset) {
619 // If the card is no longer dirty, nothing to do.
620 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
621 // No need to return that this card contains refs that point
622 // into the collection set.
623 return false;
624 }
625
626 // Construct the region representing the card.
627 HeapWord* start = _ct_bs->addr_for(card_ptr);
628 // And find the region containing it.
629 HeapRegion* r = _g1->heap_region_containing(start);
630 if (r == NULL) {
631 // Again no need to return that this card contains refs that
632 // point into the collection set.
633 return false; // Not in the G1 heap (might be in perm, for example.)
634 }
635 // Why do we have to check here whether a card is on a young region,
636 // given that we dirty young regions and, as a result, the
637 // post-barrier is supposed to filter them out and never to enqueue
638 // them? When we allocate a new region as the "allocation region" we
639 // actually dirty its cards after we release the lock, since card
640 // dirtying while holding the lock was a performance bottleneck. So,
641 // as a result, it is possible for other threads to actually
642 // allocate objects in the region (after the acquire the lock)
643 // before all the cards on the region are dirtied. This is unlikely,
644 // and it doesn't happen often, but it can happen. So, the extra
645 // check below filters out those cards.
646 if (r->is_young()) {
647 return false;
648 }
649 // While we are processing RSet buffers during the collection, we
650 // actually don't want to scan any cards on the collection set,
651 // since we don't want to update remebered sets with entries that
652 // point into the collection set, given that live objects from the
653 // collection set are about to move and such entries will be stale
654 // very soon. This change also deals with a reliability issue which
655 // involves scanning a card in the collection set and coming across
656 // an array that was being chunked and looking malformed. Note,
657 // however, that if evacuation fails, we have to scan any objects
658 // that were not moved and create any missing entries.
659 if (r->in_collection_set()) {
660 return false;
661 }
662
663 // Should we defer processing the card?
664 //
665 // Previously the result from the insert_cache call would be
666 // either card_ptr (implying that card_ptr was currently "cold"),
667 // null (meaning we had inserted the card ptr into the "hot"
668 // cache, which had some headroom), or a "hot" card ptr
669 // extracted from the "hot" cache.
670 //
671 // Now that the _card_counts cache in the ConcurrentG1Refine
672 // instance is an evicting hash table, the result we get back
673 // could be from evicting the card ptr in an already occupied
674 // bucket (in which case we have replaced the card ptr in the
675 // bucket with card_ptr and "defer" is set to false). To avoid
676 // having a data structure (updates to which would need a lock)
677 // to hold these unprocessed dirty cards, we need to immediately
678 // process card_ptr. The actions needed to be taken on return
679 // from cache_insert are summarized in the following table:
680 //
681 // res defer action
682 // --------------------------------------------------------------
683 // null false card evicted from _card_counts & replaced with
684 // card_ptr; evicted ptr added to hot cache.
685 // No need to process res; immediately process card_ptr
686 //
687 // null true card not evicted from _card_counts; card_ptr added
688 // to hot cache.
689 // Nothing to do.
690 //
691 // non-null false card evicted from _card_counts & replaced with
692 // card_ptr; evicted ptr is currently "cold" or
693 // caused an eviction from the hot cache.
694 // Immediately process res; process card_ptr.
695 //
696 // non-null true card not evicted from _card_counts; card_ptr is
697 // currently cold, or caused an eviction from hot
698 // cache.
699 // Immediately process res; no need to process card_ptr.
700
701
702 jbyte* res = card_ptr;
703 bool defer = false;
704
705 // This gets set to true if the card being refined has references
706 // that point into the collection set.
707 bool oops_into_cset = false;
708
709 if (_cg1r->use_cache()) {
710 jbyte* res = _cg1r->cache_insert(card_ptr, &defer);
711 if (res != NULL && (res != card_ptr || defer)) {
712 start = _ct_bs->addr_for(res);
713 r = _g1->heap_region_containing(start);
714 if (r != NULL) {
715 // Checking whether the region we got back from the cache
716 // is young here is inappropriate. The region could have been
717 // freed, reallocated and tagged as young while in the cache.
718 // Hence we could see its young type change at any time.
719 //
720 // Process card pointer we get back from the hot card cache. This
721 // will check whether the region containing the card is young
722 // _after_ checking that the region has been allocated from.
723 oops_into_cset = concurrentRefineOneCard_impl(res, worker_i,
724 false /* check_for_refs_into_cset */);
725 // The above call to concurrentRefineOneCard_impl is only
726 // performed if the hot card cache is enabled. This cache is
727 // disabled during an evacuation pause - which is the only
728 // time when we need know if the card contains references
729 // that point into the collection set. Also when the hot card
730 // cache is enabled, this code is executed by the concurrent
731 // refine threads - rather than the GC worker threads - and
732 // concurrentRefineOneCard_impl will return false.
733 assert(!oops_into_cset, "should not see true here");
734 }
735 }
736 }
737
738 if (!defer) {
739 oops_into_cset =
740 concurrentRefineOneCard_impl(card_ptr, worker_i, check_for_refs_into_cset);
741 // We should only be detecting that the card contains references
742 // that point into the collection set if the current thread is
743 // a GC worker thread.
744 assert(!oops_into_cset || SafepointSynchronize::is_at_safepoint(),
745 "invalid result at non safepoint");
746 }
747 return oops_into_cset;
748 }
749
750 class HRRSStatsIter: public HeapRegionClosure {
751 size_t _occupied;
752 size_t _total_mem_sz;
753 size_t _max_mem_sz;
754 HeapRegion* _max_mem_sz_region;
755 public:
756 HRRSStatsIter() :
757 _occupied(0),
758 _total_mem_sz(0),
759 _max_mem_sz(0),
760 _max_mem_sz_region(NULL)
761 {}
762
763 bool doHeapRegion(HeapRegion* r) {
764 if (r->continuesHumongous()) return false;
765 size_t mem_sz = r->rem_set()->mem_size();
766 if (mem_sz > _max_mem_sz) {
767 _max_mem_sz = mem_sz;
830 HeapRegionRemSet* rem_set = max_mem_sz_region->rem_set();
831 gclog_or_tty->print_cr(" Max size region = "HR_FORMAT", "
832 "size = "SIZE_FORMAT "K, occupied = "SIZE_FORMAT"K.",
833 HR_FORMAT_PARAMS(max_mem_sz_region),
834 (rem_set->mem_size() + K - 1)/K,
835 (rem_set->occupied() + K - 1)/K);
836 gclog_or_tty->print_cr(" Did %d coarsenings.",
837 HeapRegionRemSet::n_coarsenings());
838 }
839
840 void G1RemSet::prepare_for_verify() {
841 if (G1HRRSFlushLogBuffersOnVerify &&
842 (VerifyBeforeGC || VerifyAfterGC)
843 && !_g1->full_collection()) {
844 cleanupHRRS();
845 _g1->set_refine_cte_cl_concurrency(false);
846 if (SafepointSynchronize::is_at_safepoint()) {
847 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
848 dcqs.concatenate_logs();
849 }
850 bool cg1r_use_cache = _cg1r->use_cache();
851 _cg1r->set_use_cache(false);
852 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
853 updateRS(&into_cset_dcq, 0);
854 _g1->into_cset_dirty_card_queue_set().clear();
855 _cg1r->set_use_cache(cg1r_use_cache);
856
857 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
858 }
859 }
|
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 }
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());
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
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
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;
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 }
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