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 }
230 // Closure used for updating RSets and recording references that
231 // point into the collection set. Only called during an
232 // evacuation pause.
233
234 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
235 G1RemSet* _g1rs;
236 DirtyCardQueue* _into_cset_dcq;
237 public:
238 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
239 DirtyCardQueue* into_cset_dcq) :
240 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
241 {}
242 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
243 // The only time we care about recording cards that
244 // contain references that point into the collection set
245 // is during RSet updating within an evacuation pause.
246 // In this case worker_i should be the id of a GC worker thread.
247 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
248 assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
249
250 if (_g1rs->concurrentRefineOneCard(card_ptr, worker_i, true)) {
251 // 'card_ptr' contains references that point into the collection
252 // set. We need to record the card in the DCQS
253 // (G1CollectedHeap::into_cset_dirty_card_queue_set())
254 // that's used for that purpose.
255 //
256 // Enqueue the card
257 _into_cset_dcq->enqueue(card_ptr);
258 }
259 return true;
260 }
261 };
262
263 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) {
264 double start = os::elapsedTime();
265 // Apply the given closure to all remaining log entries.
266 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
267
268 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
269
270 // Now there should be no dirty cards.
271 if (G1RSLogCheckCardTable) {
272 CountNonCleanMemRegionClosure cl(_g1);
273 _ct_bs->mod_card_iterate(&cl);
274 // XXX This isn't true any more: keeping cards of young regions
275 // marked dirty broke it. Need some reasonable fix.
276 guarantee(cl.n() == 0, "Card table should be clean.");
277 }
278
279 _g1p->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
280 }
281
282 void G1RemSet::cleanupHRRS() {
283 HeapRegionRemSet::cleanup();
284 }
285
286 void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
287 int worker_i) {
288 #if CARD_REPEAT_HISTO
289 ct_freq_update_histo_and_reset();
290 #endif
291 if (worker_i == 0) {
292 _cg1r->clear_and_record_card_counts();
293 }
294
295 // We cache the value of 'oc' closure into the appropriate slot in the
296 // _cset_rs_update_cl for this worker
297 assert(worker_i < (int)n_workers(), "sanity");
298 _cset_rs_update_cl[worker_i] = oc;
299
300 // A DirtyCardQueue that is used to hold cards containing references
301 // that point into the collection set. This DCQ is associated with a
302 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
303 // circumstances (i.e. the pause successfully completes), these cards
304 // are just discarded (there's no need to update the RSets of regions
305 // that were in the collection set - after the pause these regions
306 // are wholly 'free' of live objects. In the event of an evacuation
307 // failure the cards/buffers in this queue set are:
308 // * passed to the DirtyCardQueueSet that is used to manage deferred
309 // RSet updates, or
310 // * scanned for references that point into the collection set
311 // and the RSet of the corresponding region in the collection set
312 // is updated immediately.
313 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
379 assert(r != NULL, "unexpected null");
380
381 // Scan oops in the card looking for references into the collection set
382 // Don't use addr_for(card_ptr + 1) which can ask for
383 // a card beyond the heap. This is not safe without a perm
384 // gen.
385 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
386 MemRegion scanRegion(start, end);
387
388 UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
389 FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
390 FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
391
392 // We can pass false as the "filter_young" parameter here as:
393 // * we should be in a STW pause,
394 // * the DCQS to which this closure is applied is used to hold
395 // references that point into the collection set from the prior
396 // RSet updating,
397 // * the post-write barrier shouldn't be logging updates to young
398 // regions (but there is a situation where this can happen - see
399 // the comment in G1RemSet::concurrentRefineOneCard below -
400 // that should not be applicable here), and
401 // * during actual RSet updating, the filtering of cards in young
402 // regions in HeapRegion::oops_on_card_seq_iterate_careful is
403 // employed.
404 // As a result, when this closure is applied to "refs into cset"
405 // DCQS, we shouldn't see any cards in young regions.
406 update_rs_cl.set_region(r);
407 HeapWord* stop_point =
408 r->oops_on_card_seq_iterate_careful(scanRegion,
409 &filter_then_update_rs_cset_oop_cl,
410 false /* filter_young */,
411 NULL /* card_ptr */);
412
413 // Since this is performed in the event of an evacuation failure, we
414 // we shouldn't see a non-null stop point
415 assert(stop_point == NULL, "saw an unallocated region");
416 return true;
417 }
418 };
419
485 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
486 }
487 return false;
488 }
489 };
490
491 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
492 ScrubRSClosure scrub_cl(region_bm, card_bm);
493 _g1->heap_region_iterate(&scrub_cl);
494 }
495
496 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
497 uint worker_num, int claim_val) {
498 ScrubRSClosure scrub_cl(region_bm, card_bm);
499 _g1->heap_region_par_iterate_chunked(&scrub_cl,
500 worker_num,
501 n_workers(),
502 claim_val);
503 }
504
505
506
507 G1TriggerClosure::G1TriggerClosure() :
508 _triggered(false) { }
509
510 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
511 OopClosure* oop_cl) :
512 _trigger_cl(t_cl), _oop_cl(oop_cl) { }
513
514 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
515 _c1(c1), _c2(c2) { }
516
517 G1UpdateRSOrPushRefOopClosure::
518 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
519 G1RemSet* rs,
520 OopsInHeapRegionClosure* push_ref_cl,
521 bool record_refs_into_cset,
522 int worker_i) :
523 _g1(g1h), _g1_rem_set(rs), _from(NULL),
524 _record_refs_into_cset(record_refs_into_cset),
525 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
526
527 bool G1RemSet::concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
528 bool check_for_refs_into_cset) {
529 // Construct the region representing the card.
530 HeapWord* start = _ct_bs->addr_for(card_ptr);
531 // And find the region containing it.
532 HeapRegion* r = _g1->heap_region_containing(start);
533 assert(r != NULL, "unexpected null");
534
535 // Don't use addr_for(card_ptr + 1) which can ask for
536 // a card beyond the heap. This is not safe without a perm
537 // gen at the upper end of the heap.
538 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
539 MemRegion dirtyRegion(start, end);
540
541 #if CARD_REPEAT_HISTO
542 init_ct_freq_table(_g1->max_capacity());
543 ct_freq_note_card(_ct_bs->index_for(start));
544 #endif
545
546 OopsInHeapRegionClosure* oops_in_heap_closure = NULL;
547 if (check_for_refs_into_cset) {
548 // ConcurrentG1RefineThreads have worker numbers larger than what
549 // _cset_rs_update_cl[] is set up to handle. But those threads should
550 // only be active outside of a collection which means that when they
551 // reach here they should have check_for_refs_into_cset == false.
552 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
553 oops_in_heap_closure = _cset_rs_update_cl[worker_i];
593 // If stop_point is non-null, then we encountered an unallocated region
594 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the
595 // card and re-enqueue: if we put off the card until a GC pause, then the
596 // unallocated portion will be filled in. Alternatively, we might try
597 // the full complexity of the technique used in "regular" precleaning.
598 if (stop_point != NULL) {
599 // The card might have gotten re-dirtied and re-enqueued while we
600 // worked. (In fact, it's pretty likely.)
601 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
602 *card_ptr = CardTableModRefBS::dirty_card_val();
603 MutexLockerEx x(Shared_DirtyCardQ_lock,
604 Mutex::_no_safepoint_check_flag);
605 DirtyCardQueue* sdcq =
606 JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
607 sdcq->enqueue(card_ptr);
608 }
609 } else {
610 _conc_refine_cards++;
611 }
612
613 return trigger_cl.triggered();
614 }
615
616 bool G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
617 bool check_for_refs_into_cset) {
618 // If the card is no longer dirty, nothing to do.
619 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
620 // No need to return that this card contains refs that point
621 // into the collection set.
622 return false;
623 }
624
625 // Construct the region representing the card.
626 HeapWord* start = _ct_bs->addr_for(card_ptr);
627 // And find the region containing it.
628 HeapRegion* r = _g1->heap_region_containing(start);
629 if (r == NULL) {
630 // Again no need to return that this card contains refs that
631 // point into the collection set.
632 return false; // Not in the G1 heap (might be in perm, for example.)
633 }
634 // Why do we have to check here whether a card is on a young region,
635 // given that we dirty young regions and, as a result, the
636 // post-barrier is supposed to filter them out and never to enqueue
637 // them? When we allocate a new region as the "allocation region" we
638 // actually dirty its cards after we release the lock, since card
639 // dirtying while holding the lock was a performance bottleneck. So,
640 // as a result, it is possible for other threads to actually
641 // allocate objects in the region (after the acquire the lock)
642 // before all the cards on the region are dirtied. This is unlikely,
643 // and it doesn't happen often, but it can happen. So, the extra
644 // check below filters out those cards.
645 if (r->is_young()) {
646 return false;
647 }
648 // While we are processing RSet buffers during the collection, we
649 // actually don't want to scan any cards on the collection set,
650 // since we don't want to update remebered sets with entries that
651 // point into the collection set, given that live objects from the
652 // collection set are about to move and such entries will be stale
653 // very soon. This change also deals with a reliability issue which
654 // involves scanning a card in the collection set and coming across
655 // an array that was being chunked and looking malformed. Note,
656 // however, that if evacuation fails, we have to scan any objects
657 // that were not moved and create any missing entries.
658 if (r->in_collection_set()) {
659 return false;
660 }
661
662 // Should we defer processing the card?
663 //
664 // Previously the result from the insert_cache call would be
665 // either card_ptr (implying that card_ptr was currently "cold"),
666 // null (meaning we had inserted the card ptr into the "hot"
667 // cache, which had some headroom), or a "hot" card ptr
668 // extracted from the "hot" cache.
669 //
670 // Now that the _card_counts cache in the ConcurrentG1Refine
671 // instance is an evicting hash table, the result we get back
672 // could be from evicting the card ptr in an already occupied
673 // bucket (in which case we have replaced the card ptr in the
674 // bucket with card_ptr and "defer" is set to false). To avoid
675 // having a data structure (updates to which would need a lock)
676 // to hold these unprocessed dirty cards, we need to immediately
677 // process card_ptr. The actions needed to be taken on return
678 // from cache_insert are summarized in the following table:
679 //
680 // res defer action
681 // --------------------------------------------------------------
682 // null false card evicted from _card_counts & replaced with
683 // card_ptr; evicted ptr added to hot cache.
684 // No need to process res; immediately process card_ptr
685 //
686 // null true card not evicted from _card_counts; card_ptr added
687 // to hot cache.
688 // Nothing to do.
689 //
690 // non-null false card evicted from _card_counts & replaced with
691 // card_ptr; evicted ptr is currently "cold" or
692 // caused an eviction from the hot cache.
693 // Immediately process res; process card_ptr.
694 //
695 // non-null true card not evicted from _card_counts; card_ptr is
696 // currently cold, or caused an eviction from hot
697 // cache.
698 // Immediately process res; no need to process card_ptr.
699
700
701 jbyte* res = card_ptr;
702 bool defer = false;
703
704 // This gets set to true if the card being refined has references
705 // that point into the collection set.
706 bool oops_into_cset = false;
707
708 if (_cg1r->use_cache()) {
709 jbyte* res = _cg1r->cache_insert(card_ptr, &defer);
710 if (res != NULL && (res != card_ptr || defer)) {
711 start = _ct_bs->addr_for(res);
712 r = _g1->heap_region_containing(start);
713 if (r != NULL) {
714 // Checking whether the region we got back from the cache
715 // is young here is inappropriate. The region could have been
716 // freed, reallocated and tagged as young while in the cache.
717 // Hence we could see its young type change at any time.
718 //
719 // Process card pointer we get back from the hot card cache. This
720 // will check whether the region containing the card is young
721 // _after_ checking that the region has been allocated from.
722 oops_into_cset = concurrentRefineOneCard_impl(res, worker_i,
723 false /* check_for_refs_into_cset */);
724 // The above call to concurrentRefineOneCard_impl is only
725 // performed if the hot card cache is enabled. This cache is
726 // disabled during an evacuation pause - which is the only
727 // time when we need know if the card contains references
728 // that point into the collection set. Also when the hot card
729 // cache is enabled, this code is executed by the concurrent
730 // refine threads - rather than the GC worker threads - and
731 // concurrentRefineOneCard_impl will return false.
732 assert(!oops_into_cset, "should not see true here");
733 }
734 }
735 }
736
737 if (!defer) {
738 oops_into_cset =
739 concurrentRefineOneCard_impl(card_ptr, worker_i, check_for_refs_into_cset);
740 // We should only be detecting that the card contains references
741 // that point into the collection set if the current thread is
742 // a GC worker thread.
743 assert(!oops_into_cset || SafepointSynchronize::is_at_safepoint(),
744 "invalid result at non safepoint");
745 }
746 return oops_into_cset;
747 }
748
749 class HRRSStatsIter: public HeapRegionClosure {
750 size_t _occupied;
751 size_t _total_mem_sz;
752 size_t _max_mem_sz;
753 HeapRegion* _max_mem_sz_region;
754 public:
755 HRRSStatsIter() :
756 _occupied(0),
757 _total_mem_sz(0),
758 _max_mem_sz(0),
759 _max_mem_sz_region(NULL)
760 {}
761
762 bool doHeapRegion(HeapRegion* r) {
763 if (r->continuesHumongous()) return false;
764 size_t mem_sz = r->rem_set()->mem_size();
765 if (mem_sz > _max_mem_sz) {
766 _max_mem_sz = mem_sz;
829 HeapRegionRemSet* rem_set = max_mem_sz_region->rem_set();
830 gclog_or_tty->print_cr(" Max size region = "HR_FORMAT", "
831 "size = "SIZE_FORMAT "K, occupied = "SIZE_FORMAT"K.",
832 HR_FORMAT_PARAMS(max_mem_sz_region),
833 (rem_set->mem_size() + K - 1)/K,
834 (rem_set->occupied() + K - 1)/K);
835 gclog_or_tty->print_cr(" Did %d coarsenings.",
836 HeapRegionRemSet::n_coarsenings());
837 }
838
839 void G1RemSet::prepare_for_verify() {
840 if (G1HRRSFlushLogBuffersOnVerify &&
841 (VerifyBeforeGC || VerifyAfterGC)
842 && !_g1->full_collection()) {
843 cleanupHRRS();
844 _g1->set_refine_cte_cl_concurrency(false);
845 if (SafepointSynchronize::is_at_safepoint()) {
846 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
847 dcqs.concatenate_logs();
848 }
849 bool cg1r_use_cache = _cg1r->use_cache();
850 _cg1r->set_use_cache(false);
851 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
852 updateRS(&into_cset_dcq, 0);
853 _g1->into_cset_dirty_card_queue_set().clear();
854 _cg1r->set_use_cache(cg1r_use_cache);
855
856 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
857 }
858 }
|
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 }
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->refine_card(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
293 // We cache the value of 'oc' closure into the appropriate slot in the
294 // _cset_rs_update_cl for this worker
295 assert(worker_i < (int)n_workers(), "sanity");
296 _cset_rs_update_cl[worker_i] = oc;
297
298 // A DirtyCardQueue that is used to hold cards containing references
299 // that point into the collection set. This DCQ is associated with a
300 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
301 // circumstances (i.e. the pause successfully completes), these cards
302 // are just discarded (there's no need to update the RSets of regions
303 // that were in the collection set - after the pause these regions
304 // are wholly 'free' of live objects. In the event of an evacuation
305 // failure the cards/buffers in this queue set are:
306 // * passed to the DirtyCardQueueSet that is used to manage deferred
307 // RSet updates, or
308 // * scanned for references that point into the collection set
309 // and the RSet of the corresponding region in the collection set
310 // is updated immediately.
311 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
377 assert(r != NULL, "unexpected null");
378
379 // Scan oops in the card looking for references into the collection set
380 // Don't use addr_for(card_ptr + 1) which can ask for
381 // a card beyond the heap. This is not safe without a perm
382 // gen.
383 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
384 MemRegion scanRegion(start, end);
385
386 UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
387 FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
388 FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
389
390 // We can pass false as the "filter_young" parameter here as:
391 // * we should be in a STW pause,
392 // * the DCQS to which this closure is applied is used to hold
393 // references that point into the collection set from the prior
394 // RSet updating,
395 // * the post-write barrier shouldn't be logging updates to young
396 // regions (but there is a situation where this can happen - see
397 // the comment in G1RemSet::refine_card() below -
398 // that should not be applicable here), and
399 // * during actual RSet updating, the filtering of cards in young
400 // regions in HeapRegion::oops_on_card_seq_iterate_careful is
401 // employed.
402 // As a result, when this closure is applied to "refs into cset"
403 // DCQS, we shouldn't see any cards in young regions.
404 update_rs_cl.set_region(r);
405 HeapWord* stop_point =
406 r->oops_on_card_seq_iterate_careful(scanRegion,
407 &filter_then_update_rs_cset_oop_cl,
408 false /* filter_young */,
409 NULL /* card_ptr */);
410
411 // Since this is performed in the event of an evacuation failure, we
412 // we shouldn't see a non-null stop point
413 assert(stop_point == NULL, "saw an unallocated region");
414 return true;
415 }
416 };
417
483 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
484 }
485 return false;
486 }
487 };
488
489 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
490 ScrubRSClosure scrub_cl(region_bm, card_bm);
491 _g1->heap_region_iterate(&scrub_cl);
492 }
493
494 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
495 uint worker_num, int claim_val) {
496 ScrubRSClosure scrub_cl(region_bm, card_bm);
497 _g1->heap_region_par_iterate_chunked(&scrub_cl,
498 worker_num,
499 n_workers(),
500 claim_val);
501 }
502
503 G1TriggerClosure::G1TriggerClosure() :
504 _triggered(false) { }
505
506 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
507 OopClosure* oop_cl) :
508 _trigger_cl(t_cl), _oop_cl(oop_cl) { }
509
510 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
511 _c1(c1), _c2(c2) { }
512
513 G1UpdateRSOrPushRefOopClosure::
514 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
515 G1RemSet* rs,
516 OopsInHeapRegionClosure* push_ref_cl,
517 bool record_refs_into_cset,
518 int worker_i) :
519 _g1(g1h), _g1_rem_set(rs), _from(NULL),
520 _record_refs_into_cset(record_refs_into_cset),
521 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
522
523 // Returns true if the given card contains references that point
524 // into the collection set, if we're checking for such references;
525 // false otherwise.
526
527 bool G1RemSet::refine_card(jbyte* card_ptr, int worker_i,
528 bool check_for_refs_into_cset) {
529
530 // If the card is no longer dirty, nothing to do.
531 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
532 // No need to return that this card contains refs that point
533 // into the collection set.
534 return false;
535 }
536
537 // Construct the region representing the card.
538 HeapWord* start = _ct_bs->addr_for(card_ptr);
539 // And find the region containing it.
540 HeapRegion* r = _g1->heap_region_containing(start);
541 if (r == NULL) {
542 // Again no need to return that this card contains refs that
543 // point into the collection set.
544 return false; // Not in the G1 heap (might be in perm, for example.)
545 }
546
547 // Why do we have to check here whether a card is on a young region,
548 // given that we dirty young regions and, as a result, the
549 // post-barrier is supposed to filter them out and never to enqueue
550 // them? When we allocate a new region as the "allocation region" we
551 // actually dirty its cards after we release the lock, since card
552 // dirtying while holding the lock was a performance bottleneck. So,
553 // as a result, it is possible for other threads to actually
554 // allocate objects in the region (after the acquire the lock)
555 // before all the cards on the region are dirtied. This is unlikely,
556 // and it doesn't happen often, but it can happen. So, the extra
557 // check below filters out those cards.
558 if (r->is_young()) {
559 return false;
560 }
561
562 // While we are processing RSet buffers during the collection, we
563 // actually don't want to scan any cards on the collection set,
564 // since we don't want to update remebered sets with entries that
565 // point into the collection set, given that live objects from the
566 // collection set are about to move and such entries will be stale
567 // very soon. This change also deals with a reliability issue which
568 // involves scanning a card in the collection set and coming across
569 // an array that was being chunked and looking malformed. Note,
570 // however, that if evacuation fails, we have to scan any objects
571 // that were not moved and create any missing entries.
572 if (r->in_collection_set()) {
573 return false;
574 }
575
576 // The result from the hot card cache insert call is either:
577 // * pointer to the current card
578 // (implying that the current card is not 'hot'),
579 // * null
580 // (meaning we had inserted the card ptr into the "hot" card cache,
581 // which had some headroom),
582 // * a pointer to a "hot" card that was evicted from the "hot" cache.
583 //
584
585 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
586 if (hot_card_cache->use_cache()) {
587 assert(!check_for_refs_into_cset, "sanity");
588 assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
589
590 card_ptr = hot_card_cache->insert(card_ptr);
591 if (card_ptr == NULL) {
592 // There was no eviction. Nothing to do.
593 return false;
594 }
595
596 start = _ct_bs->addr_for(card_ptr);
597 r = _g1->heap_region_containing(start);
598 if (r == NULL) {
599 // Not in the G1 heap
600 return false;
601 }
602
603 // Checking whether the region we got back from the cache
604 // is young here is inappropriate. The region could have been
605 // freed, reallocated and tagged as young while in the cache.
606 // Hence we could see its young type change at any time.
607 }
608
609 // Don't use addr_for(card_ptr + 1) which can ask for
610 // a card beyond the heap. This is not safe without a perm
611 // gen at the upper end of the heap.
612 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
613 MemRegion dirtyRegion(start, end);
614
615 #if CARD_REPEAT_HISTO
616 init_ct_freq_table(_g1->max_capacity());
617 ct_freq_note_card(_ct_bs->index_for(start));
618 #endif
619
620 OopsInHeapRegionClosure* oops_in_heap_closure = NULL;
621 if (check_for_refs_into_cset) {
622 // ConcurrentG1RefineThreads have worker numbers larger than what
623 // _cset_rs_update_cl[] is set up to handle. But those threads should
624 // only be active outside of a collection which means that when they
625 // reach here they should have check_for_refs_into_cset == false.
626 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
627 oops_in_heap_closure = _cset_rs_update_cl[worker_i];
667 // If stop_point is non-null, then we encountered an unallocated region
668 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the
669 // card and re-enqueue: if we put off the card until a GC pause, then the
670 // unallocated portion will be filled in. Alternatively, we might try
671 // the full complexity of the technique used in "regular" precleaning.
672 if (stop_point != NULL) {
673 // The card might have gotten re-dirtied and re-enqueued while we
674 // worked. (In fact, it's pretty likely.)
675 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
676 *card_ptr = CardTableModRefBS::dirty_card_val();
677 MutexLockerEx x(Shared_DirtyCardQ_lock,
678 Mutex::_no_safepoint_check_flag);
679 DirtyCardQueue* sdcq =
680 JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
681 sdcq->enqueue(card_ptr);
682 }
683 } else {
684 _conc_refine_cards++;
685 }
686
687 // This gets set to true if the card being refined has
688 // references that point into the collection set.
689 bool has_refs_into_cset = trigger_cl.triggered();
690
691 // We should only be detecting that the card contains references
692 // that point into the collection set if the current thread is
693 // a GC worker thread.
694 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
695 "invalid result at non safepoint");
696
697 return has_refs_into_cset;
698 }
699
700 class HRRSStatsIter: public HeapRegionClosure {
701 size_t _occupied;
702 size_t _total_mem_sz;
703 size_t _max_mem_sz;
704 HeapRegion* _max_mem_sz_region;
705 public:
706 HRRSStatsIter() :
707 _occupied(0),
708 _total_mem_sz(0),
709 _max_mem_sz(0),
710 _max_mem_sz_region(NULL)
711 {}
712
713 bool doHeapRegion(HeapRegion* r) {
714 if (r->continuesHumongous()) return false;
715 size_t mem_sz = r->rem_set()->mem_size();
716 if (mem_sz > _max_mem_sz) {
717 _max_mem_sz = mem_sz;
780 HeapRegionRemSet* rem_set = max_mem_sz_region->rem_set();
781 gclog_or_tty->print_cr(" Max size region = "HR_FORMAT", "
782 "size = "SIZE_FORMAT "K, occupied = "SIZE_FORMAT"K.",
783 HR_FORMAT_PARAMS(max_mem_sz_region),
784 (rem_set->mem_size() + K - 1)/K,
785 (rem_set->occupied() + K - 1)/K);
786 gclog_or_tty->print_cr(" Did %d coarsenings.",
787 HeapRegionRemSet::n_coarsenings());
788 }
789
790 void G1RemSet::prepare_for_verify() {
791 if (G1HRRSFlushLogBuffersOnVerify &&
792 (VerifyBeforeGC || VerifyAfterGC)
793 && !_g1->full_collection()) {
794 cleanupHRRS();
795 _g1->set_refine_cte_cl_concurrency(false);
796 if (SafepointSynchronize::is_at_safepoint()) {
797 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
798 dcqs.concatenate_logs();
799 }
800
801 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
802 bool use_hot_card_cache = hot_card_cache->use_cache();
803 hot_card_cache->set_use_cache(false);
804
805 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
806 updateRS(&into_cset_dcq, 0);
807 _g1->into_cset_dirty_card_queue_set().clear();
808
809 hot_card_cache->set_use_cache(use_hot_card_cache);
810 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
811 }
812 }
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