| /* |
| * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc/g1/g1BarrierSet.hpp" |
| #include "gc/g1/g1BlockOffsetTable.inline.hpp" |
| #include "gc/g1/g1CardTable.inline.hpp" |
| #include "gc/g1/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/g1ConcurrentRefine.hpp" |
| #include "gc/g1/g1DirtyCardQueue.hpp" |
| #include "gc/g1/g1FromCardCache.hpp" |
| #include "gc/g1/g1GCPhaseTimes.hpp" |
| #include "gc/g1/g1HotCardCache.hpp" |
| #include "gc/g1/g1OopClosures.inline.hpp" |
| #include "gc/g1/g1RootClosures.hpp" |
| #include "gc/g1/g1RemSet.hpp" |
| #include "gc/g1/g1SharedDirtyCardQueue.hpp" |
| #include "gc/g1/heapRegion.inline.hpp" |
| #include "gc/g1/heapRegionManager.inline.hpp" |
| #include "gc/g1/heapRegionRemSet.inline.hpp" |
| #include "gc/g1/sparsePRT.hpp" |
| #include "gc/shared/gcTraceTime.inline.hpp" |
| #include "gc/shared/suspendibleThreadSet.hpp" |
| #include "jfr/jfrEvents.hpp" |
| #include "memory/iterator.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/access.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/os.hpp" |
| #include "utilities/align.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| #include "utilities/stack.inline.hpp" |
| #include "utilities/ticks.hpp" |
| |
| // Collects information about the overall heap root scan progress during an evacuation. |
| // |
| // Scanning the remembered sets works by first merging all sources of cards to be |
| // scanned (log buffers, hcc, remembered sets) into a single data structure to remove |
| // duplicates and simplify work distribution. |
| // |
| // During the following card scanning we not only scan this combined set of cards, but |
| // also remember that these were completely scanned. The following evacuation passes |
| // do not scan these cards again, and so need to be preserved across increments. |
| // |
| // The representation for all the cards to scan is the card table: cards can have |
| // one of three states during GC: |
| // - clean: these cards will not be scanned in this pass |
| // - dirty: these cards will be scanned in this pass |
| // - scanned: these cards have already been scanned in a previous pass |
| // |
| // After all evacuation is done, we reset the card table to clean. |
| // |
| // Work distribution occurs on "chunk" basis, i.e. contiguous ranges of cards. As an |
| // additional optimization, during card merging we remember which regions and which |
| // chunks actually contain cards to be scanned. Threads iterate only across these |
| // regions, and only compete for chunks containing any cards. |
| // |
| // Within these chunks, a worker scans the card table on "blocks" of cards, i.e. |
| // contiguous ranges of dirty cards to be scanned. These blocks are converted to actual |
| // memory ranges and then passed on to actual scanning. |
| class G1RemSetScanState : public CHeapObj<mtGC> { |
| class G1DirtyRegions; |
| |
| size_t _max_regions; |
| |
| // Has this region that is part of the regions in the collection set been processed yet. |
| typedef bool G1RemsetIterState; |
| |
| G1RemsetIterState volatile* _collection_set_iter_state; |
| |
| // Card table iteration claim for each heap region, from 0 (completely unscanned) |
| // to (>=) HeapRegion::CardsPerRegion (completely scanned). |
| uint volatile* _card_table_scan_state; |
| |
| // Random power of two number of cards we want to claim per thread. This corresponds |
| // to a 64k of memory work chunk area for every thread. |
| // We use the same claim size as Parallel GC. No particular measurements have been |
| // performed to determine an optimal number. |
| static const uint CardsPerChunk = 128; |
| |
| uint _scan_chunks_per_region; |
| bool* _region_scan_chunks; |
| uint8_t _scan_chunks_shift; |
| public: |
| uint scan_chunk_size() const { return (uint)1 << _scan_chunks_shift; } |
| |
| // Returns whether the chunk corresponding to the given region/card in region contain a |
| // dirty card, i.e. actually needs scanning. |
| bool chunk_needs_scan(uint const region_idx, uint const card_in_region) const { |
| size_t const idx = (size_t)region_idx * _scan_chunks_per_region + (card_in_region >> _scan_chunks_shift); |
| assert(idx < (_max_regions * _scan_chunks_per_region), "Index " SIZE_FORMAT " out of bounds " SIZE_FORMAT, |
| idx, _max_regions * _scan_chunks_per_region); |
| return _region_scan_chunks[idx]; |
| } |
| |
| private: |
| // The complete set of regions which card table needs to be cleared at the end of GC because |
| // we scribbled all over them. |
| G1DirtyRegions* _all_dirty_regions; |
| // The set of regions which card table needs to be scanned for new dirty cards |
| // in the current evacuation pass. |
| G1DirtyRegions* _next_dirty_regions; |
| |
| // Set of (unique) regions that can be added to concurrently. |
| class G1DirtyRegions : public CHeapObj<mtGC> { |
| uint* _buffer; |
| uint _cur_idx; |
| size_t _max_regions; |
| |
| bool* _contains; |
| |
| public: |
| G1DirtyRegions(size_t max_regions) : |
| _buffer(NEW_C_HEAP_ARRAY(uint, max_regions, mtGC)), |
| _cur_idx(0), |
| _max_regions(max_regions), |
| _contains(NEW_C_HEAP_ARRAY(bool, max_regions, mtGC)) { |
| |
| reset(); |
| } |
| |
| static size_t chunk_size() { return M; } |
| |
| ~G1DirtyRegions() { |
| FREE_C_HEAP_ARRAY(uint, _buffer); |
| FREE_C_HEAP_ARRAY(bool, _contains); |
| } |
| |
| void reset() { |
| _cur_idx = 0; |
| ::memset(_contains, false, _max_regions * sizeof(bool)); |
| } |
| |
| uint size() const { return _cur_idx; } |
| |
| uint at(uint idx) const { |
| assert(idx < _cur_idx, "Index %u beyond valid regions", idx); |
| return _buffer[idx]; |
| } |
| |
| void add_dirty_region(uint region) { |
| if (_contains[region]) { |
| return; |
| } |
| |
| bool marked_as_dirty = Atomic::cmpxchg(true, &_contains[region], false) == false; |
| if (marked_as_dirty) { |
| uint allocated = Atomic::add(1u, &_cur_idx) - 1; |
| _buffer[allocated] = region; |
| } |
| } |
| |
| // Creates the union of this and the other G1DirtyRegions. |
| void merge(const G1DirtyRegions* other) { |
| for (uint i = 0; i < other->size(); i++) { |
| uint region = other->at(i); |
| if (!_contains[region]) { |
| _buffer[_cur_idx++] = region; |
| _contains[region] = true; |
| } |
| } |
| } |
| }; |
| |
| // Creates a snapshot of the current _top values at the start of collection to |
| // filter out card marks that we do not want to scan. |
| class G1ResetScanTopClosure : public HeapRegionClosure { |
| G1RemSetScanState* _scan_state; |
| |
| public: |
| G1ResetScanTopClosure(G1RemSetScanState* scan_state) : _scan_state(scan_state) { } |
| |
| virtual bool do_heap_region(HeapRegion* r) { |
| uint hrm_index = r->hrm_index(); |
| if (r->in_collection_set()) { |
| // Young regions had their card table marked as young at their allocation; |
| // we need to make sure that these marks are cleared at the end of GC, *but* |
| // they should not be scanned for cards. |
| // So directly add them to the "all_dirty_regions". |
| // Same for regions in the (initial) collection set: they may contain cards from |
| // the log buffers, make sure they are cleaned. |
| _scan_state->add_all_dirty_region(hrm_index); |
| } else if (r->is_old_or_humongous_or_archive()) { |
| _scan_state->set_scan_top(hrm_index, r->top()); |
| } |
| return false; |
| } |
| }; |
| // For each region, contains the maximum top() value to be used during this garbage |
| // collection. Subsumes common checks like filtering out everything but old and |
| // humongous regions outside the collection set. |
| // This is valid because we are not interested in scanning stray remembered set |
| // entries from free or archive regions. |
| HeapWord** _scan_top; |
| |
| class G1ClearCardTableTask : public AbstractGangTask { |
| G1CollectedHeap* _g1h; |
| G1DirtyRegions* _regions; |
| uint _chunk_length; |
| |
| uint volatile _cur_dirty_regions; |
| |
| G1RemSetScanState* _scan_state; |
| |
| public: |
| G1ClearCardTableTask(G1CollectedHeap* g1h, |
| G1DirtyRegions* regions, |
| uint chunk_length, |
| G1RemSetScanState* scan_state) : |
| AbstractGangTask("G1 Clear Card Table Task"), |
| _g1h(g1h), |
| _regions(regions), |
| _chunk_length(chunk_length), |
| _cur_dirty_regions(0), |
| _scan_state(scan_state) { |
| |
| assert(chunk_length > 0, "must be"); |
| } |
| |
| static uint chunk_size() { return M; } |
| |
| void work(uint worker_id) { |
| while (_cur_dirty_regions < _regions->size()) { |
| uint next = Atomic::add(_chunk_length, &_cur_dirty_regions) - _chunk_length; |
| uint max = MIN2(next + _chunk_length, _regions->size()); |
| |
| for (uint i = next; i < max; i++) { |
| HeapRegion* r = _g1h->region_at(_regions->at(i)); |
| if (!r->is_survivor()) { |
| r->clear_cardtable(); |
| } |
| } |
| } |
| } |
| }; |
| |
| // Clear the card table of "dirty" regions. |
| void clear_card_table(WorkGang* workers) { |
| uint num_regions = _all_dirty_regions->size(); |
| |
| if (num_regions == 0) { |
| return; |
| } |
| |
| uint const num_chunks = (uint)(align_up((size_t)num_regions << HeapRegion::LogCardsPerRegion, G1ClearCardTableTask::chunk_size()) / G1ClearCardTableTask::chunk_size()); |
| uint const num_workers = MIN2(num_chunks, workers->active_workers()); |
| uint const chunk_length = G1ClearCardTableTask::chunk_size() / (uint)HeapRegion::CardsPerRegion; |
| |
| // Iterate over the dirty cards region list. |
| G1ClearCardTableTask cl(G1CollectedHeap::heap(), _all_dirty_regions, chunk_length, this); |
| |
| log_debug(gc, ergo)("Running %s using %u workers for %u " |
| "units of work for %u regions.", |
| cl.name(), num_workers, num_chunks, num_regions); |
| workers->run_task(&cl, num_workers); |
| |
| #ifndef PRODUCT |
| G1CollectedHeap::heap()->verifier()->verify_card_table_cleanup(); |
| #endif |
| } |
| |
| public: |
| G1RemSetScanState() : |
| _max_regions(0), |
| _collection_set_iter_state(NULL), |
| _card_table_scan_state(NULL), |
| _scan_chunks_per_region((uint)(HeapRegion::CardsPerRegion / CardsPerChunk)), |
| _region_scan_chunks(NULL), |
| _scan_chunks_shift(0), |
| _all_dirty_regions(NULL), |
| _next_dirty_regions(NULL), |
| _scan_top(NULL) { |
| } |
| |
| ~G1RemSetScanState() { |
| FREE_C_HEAP_ARRAY(G1RemsetIterState, _collection_set_iter_state); |
| FREE_C_HEAP_ARRAY(uint, _card_table_scan_state); |
| FREE_C_HEAP_ARRAY(bool, _region_scan_chunks); |
| FREE_C_HEAP_ARRAY(HeapWord*, _scan_top); |
| } |
| |
| void initialize(size_t max_regions) { |
| assert(_collection_set_iter_state == NULL, "Must not be initialized twice"); |
| _max_regions = max_regions; |
| _collection_set_iter_state = NEW_C_HEAP_ARRAY(G1RemsetIterState, max_regions, mtGC); |
| _card_table_scan_state = NEW_C_HEAP_ARRAY(uint, max_regions, mtGC); |
| _region_scan_chunks = NEW_C_HEAP_ARRAY(bool, max_regions * _scan_chunks_per_region, mtGC); |
| |
| _scan_chunks_shift = (uint8_t)log2_intptr(HeapRegion::CardsPerRegion / _scan_chunks_per_region); |
| _scan_top = NEW_C_HEAP_ARRAY(HeapWord*, max_regions, mtGC); |
| } |
| |
| void prepare() { |
| for (size_t i = 0; i < _max_regions; i++) { |
| _collection_set_iter_state[i] = false; |
| clear_scan_top((uint)i); |
| } |
| |
| _all_dirty_regions = new G1DirtyRegions(_max_regions); |
| _next_dirty_regions = new G1DirtyRegions(_max_regions); |
| |
| G1ResetScanTopClosure cl(this); |
| G1CollectedHeap::heap()->heap_region_iterate(&cl); |
| } |
| |
| void prepare_for_merge_heap_roots() { |
| _all_dirty_regions->merge(_next_dirty_regions); |
| |
| _next_dirty_regions->reset(); |
| for (size_t i = 0; i < _max_regions; i++) { |
| _card_table_scan_state[i] = 0; |
| } |
| |
| ::memset(_region_scan_chunks, false, _max_regions * _scan_chunks_per_region * sizeof(*_region_scan_chunks)); |
| } |
| |
| // Returns whether the given region contains cards we need to scan. The remembered |
| // set and other sources may contain cards that |
| // - are in uncommitted regions |
| // - are located in the collection set |
| // - are located in free regions |
| // as we do not clean up remembered sets before merging heap roots. |
| bool contains_cards_to_process(uint const region_idx) const { |
| HeapRegion* hr = G1CollectedHeap::heap()->region_at_or_null(region_idx); |
| return (hr != NULL && !hr->in_collection_set() && hr->is_old_or_humongous_or_archive()); |
| } |
| |
| size_t num_visited_cards() const { |
| size_t result = 0; |
| for (uint i = 0; i < _max_regions * _scan_chunks_per_region; i++) { |
| if (_region_scan_chunks[i]) { |
| result++; |
| } |
| } |
| return result * CardsPerChunk; |
| } |
| |
| size_t num_cards_in_dirty_regions() const { |
| return _next_dirty_regions->size() * HeapRegion::CardsPerRegion; |
| } |
| |
| void set_chunk_region_dirty(size_t const region_card_idx) { |
| size_t chunk_idx = region_card_idx >> _scan_chunks_shift; |
| for (uint i = 0; i < _scan_chunks_per_region; i++) { |
| _region_scan_chunks[chunk_idx++] = true; |
| } |
| } |
| |
| void set_chunk_dirty(size_t const card_idx) { |
| assert((card_idx >> _scan_chunks_shift) < (_max_regions * _scan_chunks_per_region), |
| "Trying to access index " SIZE_FORMAT " out of bounds " SIZE_FORMAT, |
| card_idx >> _scan_chunks_shift, _max_regions * _scan_chunks_per_region); |
| size_t const chunk_idx = card_idx >> _scan_chunks_shift; |
| if (!_region_scan_chunks[chunk_idx]) { |
| _region_scan_chunks[chunk_idx] = true; |
| } |
| } |
| |
| void cleanup(WorkGang* workers) { |
| _all_dirty_regions->merge(_next_dirty_regions); |
| |
| clear_card_table(workers); |
| |
| delete _all_dirty_regions; |
| _all_dirty_regions = NULL; |
| |
| delete _next_dirty_regions; |
| _next_dirty_regions = NULL; |
| } |
| |
| void iterate_dirty_regions_from(HeapRegionClosure* cl, uint worker_id) { |
| uint num_regions = _next_dirty_regions->size(); |
| |
| if (num_regions == 0) { |
| return; |
| } |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| |
| WorkGang* workers = g1h->workers(); |
| uint const max_workers = workers->active_workers(); |
| |
| uint const start_pos = num_regions * worker_id / max_workers; |
| uint cur = start_pos; |
| |
| do { |
| bool result = cl->do_heap_region(g1h->region_at(_next_dirty_regions->at(cur))); |
| guarantee(!result, "Not allowed to ask for early termination."); |
| cur++; |
| if (cur == _next_dirty_regions->size()) { |
| cur = 0; |
| } |
| } while (cur != start_pos); |
| } |
| |
| // Attempt to claim the given region in the collection set for iteration. Returns true |
| // if this call caused the transition from Unclaimed to Claimed. |
| inline bool claim_collection_set_region(uint region) { |
| assert(region < _max_regions, "Tried to access invalid region %u", region); |
| if (_collection_set_iter_state[region]) { |
| return false; |
| } |
| return !Atomic::cmpxchg(true, &_collection_set_iter_state[region], false); |
| } |
| |
| bool has_cards_to_scan(uint region) { |
| assert(region < _max_regions, "Tried to access invalid region %u", region); |
| return _card_table_scan_state[region] < HeapRegion::CardsPerRegion; |
| } |
| |
| uint claim_cards_to_scan(uint region, uint increment) { |
| assert(region < _max_regions, "Tried to access invalid region %u", region); |
| return Atomic::add(increment, &_card_table_scan_state[region]) - increment; |
| } |
| |
| void add_dirty_region(uint const region) { |
| #ifdef ASSERT |
| HeapRegion* hr = G1CollectedHeap::heap()->region_at(region); |
| assert(!hr->in_collection_set() && hr->is_old_or_humongous_or_archive(), |
| "Region %u is not suitable for scanning, is %sin collection set or %s", |
| hr->hrm_index(), hr->in_collection_set() ? "" : "not ", hr->get_short_type_str()); |
| #endif |
| _next_dirty_regions->add_dirty_region(region); |
| } |
| |
| void add_all_dirty_region(uint region) { |
| #ifdef ASSERT |
| HeapRegion* hr = G1CollectedHeap::heap()->region_at(region); |
| assert(hr->in_collection_set(), |
| "Only add young regions to all dirty regions directly but %u is %s", |
| hr->hrm_index(), hr->get_short_type_str()); |
| #endif |
| _all_dirty_regions->add_dirty_region(region); |
| } |
| |
| void set_scan_top(uint region_idx, HeapWord* value) { |
| _scan_top[region_idx] = value; |
| } |
| |
| HeapWord* scan_top(uint region_idx) const { |
| return _scan_top[region_idx]; |
| } |
| |
| void clear_scan_top(uint region_idx) { |
| set_scan_top(region_idx, NULL); |
| } |
| }; |
| |
| G1RemSet::G1RemSet(G1CollectedHeap* g1h, |
| G1CardTable* ct, |
| G1HotCardCache* hot_card_cache) : |
| _scan_state(new G1RemSetScanState()), |
| _prev_period_summary(), |
| _g1h(g1h), |
| _num_conc_refined_cards(0), |
| _ct(ct), |
| _g1p(_g1h->policy()), |
| _hot_card_cache(hot_card_cache) { |
| } |
| |
| G1RemSet::~G1RemSet() { |
| delete _scan_state; |
| } |
| |
| uint G1RemSet::num_par_rem_sets() { |
| return G1DirtyCardQueueSet::num_par_ids() + G1ConcurrentRefine::max_num_threads() + MAX2(ConcGCThreads, ParallelGCThreads); |
| } |
| |
| void G1RemSet::initialize(size_t capacity, uint max_regions) { |
| G1FromCardCache::initialize(num_par_rem_sets(), max_regions); |
| _scan_state->initialize(max_regions); |
| } |
| |
| // Helper class to scan and detect ranges of cards that need to be scanned on the |
| // card table. |
| class G1CardTableScanner : public StackObj { |
| public: |
| typedef CardTable::CardValue CardValue; |
| |
| private: |
| CardValue* const _base_addr; |
| |
| CardValue* _cur_addr; |
| CardValue* const _end_addr; |
| |
| static const size_t ToScanMask = G1CardTable::g1_card_already_scanned; |
| static const size_t ExpandedToScanMask = G1CardTable::WordAlreadyScanned; |
| |
| bool cur_addr_aligned() const { |
| return ((uintptr_t)_cur_addr) % sizeof(size_t) == 0; |
| } |
| |
| bool cur_card_is_dirty() const { |
| CardValue value = *_cur_addr; |
| return (value & ToScanMask) == 0; |
| } |
| |
| bool cur_word_of_cards_contains_any_dirty_card() const { |
| assert(cur_addr_aligned(), "Current address should be aligned"); |
| size_t const value = *(size_t*)_cur_addr; |
| return (~value & ExpandedToScanMask) != 0; |
| } |
| |
| bool cur_word_of_cards_all_dirty_cards() const { |
| size_t const value = *(size_t*)_cur_addr; |
| return value == G1CardTable::WordAllDirty; |
| } |
| |
| size_t get_and_advance_pos() { |
| _cur_addr++; |
| return pointer_delta(_cur_addr, _base_addr, sizeof(CardValue)) - 1; |
| } |
| |
| public: |
| G1CardTableScanner(CardValue* start_card, size_t size) : |
| _base_addr(start_card), |
| _cur_addr(start_card), |
| _end_addr(start_card + size) { |
| |
| assert(is_aligned(start_card, sizeof(size_t)), "Unaligned start addr " PTR_FORMAT, p2i(start_card)); |
| assert(is_aligned(size, sizeof(size_t)), "Unaligned size " SIZE_FORMAT, size); |
| } |
| |
| size_t find_next_dirty() { |
| while (!cur_addr_aligned()) { |
| if (cur_card_is_dirty()) { |
| return get_and_advance_pos(); |
| } |
| _cur_addr++; |
| } |
| |
| assert(cur_addr_aligned(), "Current address should be aligned now."); |
| while (_cur_addr != _end_addr) { |
| if (cur_word_of_cards_contains_any_dirty_card()) { |
| for (size_t i = 0; i < sizeof(size_t); i++) { |
| if (cur_card_is_dirty()) { |
| return get_and_advance_pos(); |
| } |
| _cur_addr++; |
| } |
| assert(false, "Should not reach here given we detected a dirty card in the word."); |
| } |
| _cur_addr += sizeof(size_t); |
| } |
| return get_and_advance_pos(); |
| } |
| |
| size_t find_next_non_dirty() { |
| assert(_cur_addr <= _end_addr, "Not allowed to search for marks after area."); |
| |
| while (!cur_addr_aligned()) { |
| if (!cur_card_is_dirty()) { |
| return get_and_advance_pos(); |
| } |
| _cur_addr++; |
| } |
| |
| assert(cur_addr_aligned(), "Current address should be aligned now."); |
| while (_cur_addr != _end_addr) { |
| if (!cur_word_of_cards_all_dirty_cards()) { |
| for (size_t i = 0; i < sizeof(size_t); i++) { |
| if (!cur_card_is_dirty()) { |
| return get_and_advance_pos(); |
| } |
| _cur_addr++; |
| } |
| assert(false, "Should not reach here given we detected a non-dirty card in the word."); |
| } |
| _cur_addr += sizeof(size_t); |
| } |
| return get_and_advance_pos(); |
| } |
| }; |
| |
| // Helper class to claim dirty chunks within the card table. |
| class G1CardTableChunkClaimer { |
| G1RemSetScanState* _scan_state; |
| uint _region_idx; |
| uint _cur_claim; |
| |
| public: |
| G1CardTableChunkClaimer(G1RemSetScanState* scan_state, uint region_idx) : |
| _scan_state(scan_state), |
| _region_idx(region_idx), |
| _cur_claim(0) { |
| guarantee(size() <= HeapRegion::CardsPerRegion, "Should not claim more space than possible."); |
| } |
| |
| bool has_next() { |
| while (true) { |
| _cur_claim = _scan_state->claim_cards_to_scan(_region_idx, size()); |
| if (_cur_claim >= HeapRegion::CardsPerRegion) { |
| return false; |
| } |
| if (_scan_state->chunk_needs_scan(_region_idx, _cur_claim)) { |
| return true; |
| } |
| } |
| } |
| |
| uint value() const { return _cur_claim; } |
| uint size() const { return _scan_state->scan_chunk_size(); } |
| }; |
| |
| // Scans a heap region for dirty cards. |
| class G1ScanHRForRegionClosure : public HeapRegionClosure { |
| G1CollectedHeap* _g1h; |
| G1CardTable* _ct; |
| G1BlockOffsetTable* _bot; |
| |
| G1ParScanThreadState* _pss; |
| |
| G1RemSetScanState* _scan_state; |
| |
| G1GCPhaseTimes::GCParPhases _phase; |
| |
| uint _worker_id; |
| |
| size_t _cards_scanned; |
| size_t _blocks_scanned; |
| size_t _chunks_claimed; |
| |
| Tickspan _rem_set_root_scan_time; |
| Tickspan _rem_set_trim_partially_time; |
| |
| // The address to which this thread already scanned (walked the heap) up to during |
| // card scanning (exclusive). |
| HeapWord* _scanned_to; |
| |
| HeapWord* scan_memregion(uint region_idx_for_card, MemRegion mr) { |
| HeapRegion* const card_region = _g1h->region_at(region_idx_for_card); |
| G1ScanCardClosure card_cl(_g1h, _pss); |
| |
| HeapWord* const scanned_to = card_region->oops_on_memregion_seq_iterate_careful<true>(mr, &card_cl); |
| assert(scanned_to != NULL, "Should be able to scan range"); |
| assert(scanned_to >= mr.end(), "Scanned to " PTR_FORMAT " less than range " PTR_FORMAT, p2i(scanned_to), p2i(mr.end())); |
| |
| _pss->trim_queue_partially(); |
| return scanned_to; |
| } |
| |
| void do_claimed_block(uint const region_idx_for_card, size_t const first_card, size_t const num_cards) { |
| HeapWord* const card_start = _bot->address_for_index_raw(first_card); |
| #ifdef ASSERT |
| HeapRegion* hr = _g1h->region_at_or_null(region_idx_for_card); |
| assert(hr == NULL || hr->is_in_reserved(card_start), |
| "Card start " PTR_FORMAT " to scan outside of region %u", p2i(card_start), _g1h->region_at(region_idx_for_card)->hrm_index()); |
| #endif |
| HeapWord* const top = _scan_state->scan_top(region_idx_for_card); |
| if (card_start >= top) { |
| return; |
| } |
| |
| HeapWord* scan_end = MIN2(card_start + (num_cards << BOTConstants::LogN_words), top); |
| if (_scanned_to >= scan_end) { |
| return; |
| } |
| MemRegion mr(MAX2(card_start, _scanned_to), scan_end); |
| _scanned_to = scan_memregion(region_idx_for_card, mr); |
| |
| _cards_scanned += num_cards; |
| } |
| |
| ALWAYSINLINE void do_card_block(uint const region_idx, size_t const first_card, size_t const num_cards) { |
| _ct->mark_as_scanned(first_card, num_cards); |
| do_claimed_block(region_idx, first_card, num_cards); |
| _blocks_scanned++; |
| } |
| |
| void scan_heap_roots(HeapRegion* r) { |
| EventGCPhaseParallel event; |
| uint const region_idx = r->hrm_index(); |
| |
| ResourceMark rm; |
| |
| G1CardTableChunkClaimer claim(_scan_state, region_idx); |
| |
| // Set the current scan "finger" to NULL for every heap region to scan. Since |
| // the claim value is monotonically increasing, the check to not scan below this |
| // will filter out objects spanning chunks within the region too then, as opposed |
| // to resetting this value for every claim. |
| _scanned_to = NULL; |
| |
| while (claim.has_next()) { |
| size_t const region_card_base_idx = ((size_t)region_idx << HeapRegion::LogCardsPerRegion) + claim.value(); |
| CardTable::CardValue* const base_addr = _ct->byte_for_index(region_card_base_idx); |
| |
| G1CardTableScanner scan(base_addr, claim.size()); |
| |
| size_t first_scan_idx = scan.find_next_dirty(); |
| while (first_scan_idx != claim.size()) { |
| assert(*_ct->byte_for_index(region_card_base_idx + first_scan_idx) <= 0x1, "is %d at region %u idx " SIZE_FORMAT, *_ct->byte_for_index(region_card_base_idx + first_scan_idx), region_idx, first_scan_idx); |
| |
| size_t const last_scan_idx = scan.find_next_non_dirty(); |
| size_t const len = last_scan_idx - first_scan_idx; |
| |
| do_card_block(region_idx, region_card_base_idx + first_scan_idx, len); |
| |
| if (last_scan_idx == claim.size()) { |
| break; |
| } |
| |
| first_scan_idx = scan.find_next_dirty(); |
| } |
| _chunks_claimed++; |
| } |
| |
| event.commit(GCId::current(), _worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ScanHR)); |
| } |
| |
| public: |
| G1ScanHRForRegionClosure(G1RemSetScanState* scan_state, |
| G1ParScanThreadState* pss, |
| uint worker_id, |
| G1GCPhaseTimes::GCParPhases phase) : |
| _g1h(G1CollectedHeap::heap()), |
| _ct(_g1h->card_table()), |
| _bot(_g1h->bot()), |
| _pss(pss), |
| _scan_state(scan_state), |
| _phase(phase), |
| _worker_id(worker_id), |
| _cards_scanned(0), |
| _blocks_scanned(0), |
| _chunks_claimed(0), |
| _rem_set_root_scan_time(), |
| _rem_set_trim_partially_time(), |
| _scanned_to(NULL) { |
| } |
| |
| bool do_heap_region(HeapRegion* r) { |
| assert(!r->in_collection_set() && r->is_old_or_humongous_or_archive(), |
| "Should only be called on old gen non-collection set regions but region %u is not.", |
| r->hrm_index()); |
| uint const region_idx = r->hrm_index(); |
| |
| if (_scan_state->has_cards_to_scan(region_idx)) { |
| G1EvacPhaseWithTrimTimeTracker timer(_pss, _rem_set_root_scan_time, _rem_set_trim_partially_time); |
| scan_heap_roots(r); |
| } |
| return false; |
| } |
| |
| Tickspan rem_set_root_scan_time() const { return _rem_set_root_scan_time; } |
| Tickspan rem_set_trim_partially_time() const { return _rem_set_trim_partially_time; } |
| |
| size_t cards_scanned() const { return _cards_scanned; } |
| size_t blocks_scanned() const { return _blocks_scanned; } |
| size_t chunks_claimed() const { return _chunks_claimed; } |
| }; |
| |
| void G1RemSet::scan_heap_roots(G1ParScanThreadState* pss, |
| uint worker_id, |
| G1GCPhaseTimes::GCParPhases scan_phase, |
| G1GCPhaseTimes::GCParPhases objcopy_phase) { |
| G1ScanHRForRegionClosure cl(_scan_state, pss, worker_id, scan_phase); |
| _scan_state->iterate_dirty_regions_from(&cl, worker_id); |
| |
| G1GCPhaseTimes* p = _g1p->phase_times(); |
| |
| p->record_or_add_time_secs(objcopy_phase, worker_id, cl.rem_set_trim_partially_time().seconds()); |
| |
| p->record_or_add_time_secs(scan_phase, worker_id, cl.rem_set_root_scan_time().seconds()); |
| p->record_or_add_thread_work_item(scan_phase, worker_id, cl.cards_scanned(), G1GCPhaseTimes::ScanHRScannedCards); |
| p->record_or_add_thread_work_item(scan_phase, worker_id, cl.blocks_scanned(), G1GCPhaseTimes::ScanHRScannedBlocks); |
| p->record_or_add_thread_work_item(scan_phase, worker_id, cl.chunks_claimed(), G1GCPhaseTimes::ScanHRClaimedChunks); |
| } |
| |
| // Heap region closure to be applied to all regions in the current collection set |
| // increment to fix up non-card related roots. |
| class G1ScanCollectionSetRegionClosure : public HeapRegionClosure { |
| G1ParScanThreadState* _pss; |
| G1RemSetScanState* _scan_state; |
| |
| G1GCPhaseTimes::GCParPhases _scan_phase; |
| G1GCPhaseTimes::GCParPhases _code_roots_phase; |
| |
| uint _worker_id; |
| |
| size_t _opt_refs_scanned; |
| size_t _opt_refs_memory_used; |
| |
| Tickspan _strong_code_root_scan_time; |
| Tickspan _strong_code_trim_partially_time; |
| |
| Tickspan _rem_set_opt_root_scan_time; |
| Tickspan _rem_set_opt_trim_partially_time; |
| |
| void scan_opt_rem_set_roots(HeapRegion* r) { |
| EventGCPhaseParallel event; |
| |
| G1OopStarChunkedList* opt_rem_set_list = _pss->oops_into_optional_region(r); |
| |
| G1ScanCardClosure scan_cl(G1CollectedHeap::heap(), _pss); |
| G1ScanRSForOptionalClosure cl(G1CollectedHeap::heap(), &scan_cl); |
| _opt_refs_scanned += opt_rem_set_list->oops_do(&cl, _pss->closures()->raw_strong_oops()); |
| _opt_refs_memory_used += opt_rem_set_list->used_memory(); |
| |
| event.commit(GCId::current(), _worker_id, G1GCPhaseTimes::phase_name(_scan_phase)); |
| } |
| |
| public: |
| G1ScanCollectionSetRegionClosure(G1RemSetScanState* scan_state, |
| G1ParScanThreadState* pss, |
| uint worker_i, |
| G1GCPhaseTimes::GCParPhases scan_phase, |
| G1GCPhaseTimes::GCParPhases code_roots_phase) : |
| _pss(pss), |
| _scan_state(scan_state), |
| _scan_phase(scan_phase), |
| _code_roots_phase(code_roots_phase), |
| _worker_id(worker_i), |
| _opt_refs_scanned(0), |
| _opt_refs_memory_used(0), |
| _strong_code_root_scan_time(), |
| _strong_code_trim_partially_time(), |
| _rem_set_opt_root_scan_time(), |
| _rem_set_opt_trim_partially_time() { } |
| |
| bool do_heap_region(HeapRegion* r) { |
| uint const region_idx = r->hrm_index(); |
| |
| // The individual references for the optional remembered set are per-worker, so we |
| // always need to scan them. |
| if (r->has_index_in_opt_cset()) { |
| G1EvacPhaseWithTrimTimeTracker timer(_pss, _rem_set_opt_root_scan_time, _rem_set_opt_trim_partially_time); |
| scan_opt_rem_set_roots(r); |
| } |
| |
| if (_scan_state->claim_collection_set_region(region_idx)) { |
| EventGCPhaseParallel event; |
| |
| G1EvacPhaseWithTrimTimeTracker timer(_pss, _strong_code_root_scan_time, _strong_code_trim_partially_time); |
| // Scan the strong code root list attached to the current region |
| r->strong_code_roots_do(_pss->closures()->weak_codeblobs()); |
| |
| event.commit(GCId::current(), _worker_id, G1GCPhaseTimes::phase_name(_code_roots_phase)); |
| } |
| |
| return false; |
| } |
| |
| Tickspan strong_code_root_scan_time() const { return _strong_code_root_scan_time; } |
| Tickspan strong_code_root_trim_partially_time() const { return _strong_code_trim_partially_time; } |
| |
| Tickspan rem_set_opt_root_scan_time() const { return _rem_set_opt_root_scan_time; } |
| Tickspan rem_set_opt_trim_partially_time() const { return _rem_set_opt_trim_partially_time; } |
| |
| size_t opt_refs_scanned() const { return _opt_refs_scanned; } |
| size_t opt_refs_memory_used() const { return _opt_refs_memory_used; } |
| }; |
| |
| void G1RemSet::scan_collection_set_regions(G1ParScanThreadState* pss, |
| uint worker_id, |
| G1GCPhaseTimes::GCParPhases scan_phase, |
| G1GCPhaseTimes::GCParPhases coderoots_phase, |
| G1GCPhaseTimes::GCParPhases objcopy_phase) { |
| G1ScanCollectionSetRegionClosure cl(_scan_state, pss, worker_id, scan_phase, coderoots_phase); |
| _g1h->collection_set_iterate_increment_from(&cl, worker_id); |
| |
| G1GCPhaseTimes* p = _g1h->phase_times(); |
| |
| p->record_or_add_time_secs(scan_phase, worker_id, cl.rem_set_opt_root_scan_time().seconds()); |
| p->record_or_add_time_secs(scan_phase, worker_id, cl.rem_set_opt_trim_partially_time().seconds()); |
| |
| p->record_or_add_time_secs(coderoots_phase, worker_id, cl.strong_code_root_scan_time().seconds()); |
| p->add_time_secs(objcopy_phase, worker_id, cl.strong_code_root_trim_partially_time().seconds()); |
| |
| // At this time we record some metrics only for the evacuations after the initial one. |
| if (scan_phase == G1GCPhaseTimes::OptScanHR) { |
| p->record_or_add_thread_work_item(scan_phase, worker_id, cl.opt_refs_scanned(), G1GCPhaseTimes::ScanHRScannedOptRefs); |
| p->record_or_add_thread_work_item(scan_phase, worker_id, cl.opt_refs_memory_used(), G1GCPhaseTimes::ScanHRUsedMemory); |
| } |
| } |
| |
| void G1RemSet::prepare_for_scan_heap_roots() { |
| G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); |
| dcqs.concatenate_logs(); |
| |
| _scan_state->prepare(); |
| } |
| |
| class G1MergeHeapRootsTask : public AbstractGangTask { |
| |
| // Visitor for remembered sets, dropping entries onto the card table. |
| class G1MergeCardSetClosure : public HeapRegionClosure { |
| G1RemSetScanState* _scan_state; |
| G1CardTable* _ct; |
| |
| uint _merged_sparse; |
| uint _merged_fine; |
| uint _merged_coarse; |
| |
| // Returns if the region contains cards we need to scan. If so, remember that |
| // region in the current set of dirty regions. |
| bool remember_if_interesting(uint const region_idx) { |
| if (!_scan_state->contains_cards_to_process(region_idx)) { |
| return false; |
| } |
| _scan_state->add_dirty_region(region_idx); |
| return true; |
| } |
| public: |
| G1MergeCardSetClosure(G1RemSetScanState* scan_state) : |
| _scan_state(scan_state), |
| _ct(G1CollectedHeap::heap()->card_table()), |
| _merged_sparse(0), |
| _merged_fine(0), |
| _merged_coarse(0) { } |
| |
| void next_coarse_prt(uint const region_idx) { |
| if (!remember_if_interesting(region_idx)) { |
| return; |
| } |
| |
| _merged_coarse++; |
| |
| size_t region_base_idx = (size_t)region_idx << HeapRegion::LogCardsPerRegion; |
| _ct->mark_region_dirty(region_base_idx, HeapRegion::CardsPerRegion); |
| _scan_state->set_chunk_region_dirty(region_base_idx); |
| } |
| |
| void next_fine_prt(uint const region_idx, BitMap* bm) { |
| if (!remember_if_interesting(region_idx)) { |
| return; |
| } |
| |
| _merged_fine++; |
| |
| size_t const region_base_idx = (size_t)region_idx << HeapRegion::LogCardsPerRegion; |
| BitMap::idx_t cur = bm->get_next_one_offset(0); |
| while (cur != bm->size()) { |
| _ct->mark_clean_as_dirty(region_base_idx + cur); |
| _scan_state->set_chunk_dirty(region_base_idx + cur); |
| cur = bm->get_next_one_offset(cur + 1); |
| } |
| } |
| |
| void next_sparse_prt(uint const region_idx, SparsePRTEntry::card_elem_t* cards, uint const num_cards) { |
| if (!remember_if_interesting(region_idx)) { |
| return; |
| } |
| |
| _merged_sparse++; |
| |
| size_t const region_base_idx = (size_t)region_idx << HeapRegion::LogCardsPerRegion; |
| for (uint i = 0; i < num_cards; i++) { |
| size_t card_idx = region_base_idx + cards[i]; |
| _ct->mark_clean_as_dirty(card_idx); |
| _scan_state->set_chunk_dirty(card_idx); |
| } |
| } |
| |
| virtual bool do_heap_region(HeapRegion* r) { |
| assert(r->in_collection_set() || r->is_starts_humongous(), "must be"); |
| |
| HeapRegionRemSet* rem_set = r->rem_set(); |
| if (!rem_set->is_empty()) { |
| rem_set->iterate_prts(*this); |
| } |
| |
| return false; |
| } |
| |
| size_t merged_sparse() const { return _merged_sparse; } |
| size_t merged_fine() const { return _merged_fine; } |
| size_t merged_coarse() const { return _merged_coarse; } |
| }; |
| |
| // Visitor for the remembered sets of humongous candidate regions to merge their |
| // remembered set into the card table. |
| class G1FlushHumongousCandidateRemSets : public HeapRegionClosure { |
| G1MergeCardSetClosure _cl; |
| |
| public: |
| G1FlushHumongousCandidateRemSets(G1RemSetScanState* scan_state) : _cl(scan_state) { } |
| |
| virtual bool do_heap_region(HeapRegion* r) { |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| |
| if (!r->is_starts_humongous() || |
| !g1h->region_attr(r->hrm_index()).is_humongous() || |
| r->rem_set()->is_empty()) { |
| return false; |
| } |
| |
| guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), |
| "Found a not-small remembered set here. This is inconsistent with previous assumptions."); |
| |
| _cl.do_heap_region(r); |
| |
| // We should only clear the card based remembered set here as we will not |
| // implicitly rebuild anything else during eager reclaim. Note that at the moment |
| // (and probably never) we do not enter this path if there are other kind of |
| // remembered sets for this region. |
| r->rem_set()->clear_locked(true /* only_cardset */); |
| // Clear_locked() above sets the state to Empty. However we want to continue |
| // collecting remembered set entries for humongous regions that were not |
| // reclaimed. |
| r->rem_set()->set_state_complete(); |
| #ifdef ASSERT |
| G1HeapRegionAttr region_attr = g1h->region_attr(r->hrm_index()); |
| assert(region_attr.needs_remset_update(), "must be"); |
| #endif |
| assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); |
| |
| return false; |
| } |
| |
| size_t merged_sparse() const { return _cl.merged_sparse(); } |
| size_t merged_fine() const { return _cl.merged_fine(); } |
| size_t merged_coarse() const { return _cl.merged_coarse(); } |
| }; |
| |
| // Visitor for the log buffer entries to merge them into the card table. |
| class G1MergeLogBufferCardsClosure : public G1CardTableEntryClosure { |
| G1RemSetScanState* _scan_state; |
| G1CardTable* _ct; |
| |
| size_t _cards_dirty; |
| size_t _cards_skipped; |
| public: |
| G1MergeLogBufferCardsClosure(G1CollectedHeap* g1h, G1RemSetScanState* scan_state) : |
| _scan_state(scan_state), _ct(g1h->card_table()), _cards_dirty(0), _cards_skipped(0) |
| {} |
| |
| bool do_card_ptr(CardValue* card_ptr, uint worker_i) { |
| // The only time we care about recording cards that |
| // contain references that point into the collection set |
| // is during RSet updating within an evacuation pause. |
| // In this case worker_id should be the id of a GC worker thread. |
| assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause"); |
| |
| uint const region_idx = _ct->region_idx_for(card_ptr); |
| |
| // The second clause must come after - the log buffers might contain cards to uncommited |
| // regions. |
| // This code may count duplicate entries in the log buffers (even if rare) multiple |
| // times. |
| if (_scan_state->contains_cards_to_process(region_idx) && (*card_ptr == G1CardTable::dirty_card_val())) { |
| _scan_state->add_dirty_region(region_idx); |
| _scan_state->set_chunk_dirty(_ct->index_for_cardvalue(card_ptr)); |
| _cards_dirty++; |
| } else { |
| // We may have had dirty cards in the (initial) collection set (or the |
| // young regions which are always in the initial collection set). We do |
| // not fix their cards here: we already added these regions to the set of |
| // regions to clear the card table at the end during the prepare() phase. |
| _cards_skipped++; |
| } |
| return true; |
| } |
| |
| size_t cards_dirty() const { return _cards_dirty; } |
| size_t cards_skipped() const { return _cards_skipped; } |
| }; |
| |
| HeapRegionClaimer _hr_claimer; |
| G1RemSetScanState* _scan_state; |
| bool _initial_evacuation; |
| |
| volatile bool _fast_reclaim_handled; |
| |
| public: |
| G1MergeHeapRootsTask(G1RemSetScanState* scan_state, uint num_workers, bool initial_evacuation) : |
| AbstractGangTask("G1 Merge Heap Roots"), |
| _hr_claimer(num_workers), |
| _scan_state(scan_state), |
| _initial_evacuation(initial_evacuation), |
| _fast_reclaim_handled(false) { } |
| |
| virtual void work(uint worker_id) { |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| G1GCPhaseTimes* p = g1h->phase_times(); |
| |
| G1GCPhaseTimes::GCParPhases merge_remset_phase = _initial_evacuation ? |
| G1GCPhaseTimes::MergeRS : |
| G1GCPhaseTimes::OptMergeRS; |
| |
| // We schedule flushing the remembered sets of humongous fast reclaim candidates |
| // onto the card table first to allow the remaining parallelized tasks hide it. |
| if (_initial_evacuation && |
| p->fast_reclaim_humongous_candidates() > 0 && |
| !_fast_reclaim_handled && |
| !Atomic::cmpxchg(true, &_fast_reclaim_handled, false)) { |
| |
| G1FlushHumongousCandidateRemSets cl(_scan_state); |
| g1h->heap_region_iterate(&cl); |
| |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_sparse(), G1GCPhaseTimes::MergeRSMergedSparse); |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_fine(), G1GCPhaseTimes::MergeRSMergedFine); |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_coarse(), G1GCPhaseTimes::MergeRSMergedCoarse); |
| } |
| |
| // Merge remembered sets of current candidates. |
| { |
| G1GCParPhaseTimesTracker x(p, merge_remset_phase, worker_id, _initial_evacuation /* must_record */); |
| G1MergeCardSetClosure cl(_scan_state); |
| g1h->collection_set_iterate_increment_from(&cl, &_hr_claimer, worker_id); |
| |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_sparse(), G1GCPhaseTimes::MergeRSMergedSparse); |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_fine(), G1GCPhaseTimes::MergeRSMergedFine); |
| p->record_or_add_thread_work_item(merge_remset_phase, worker_id, cl.merged_coarse(), G1GCPhaseTimes::MergeRSMergedCoarse); |
| } |
| |
| // Apply closure to log entries in the HCC. |
| if (_initial_evacuation && G1HotCardCache::default_use_cache()) { |
| assert(merge_remset_phase == G1GCPhaseTimes::MergeRS, "Wrong merge phase"); |
| G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::MergeHCC, worker_id); |
| G1MergeLogBufferCardsClosure cl(g1h, _scan_state); |
| g1h->iterate_hcc_closure(&cl, worker_id); |
| } |
| |
| // Now apply the closure to all remaining log entries. |
| if (_initial_evacuation) { |
| assert(merge_remset_phase == G1GCPhaseTimes::MergeRS, "Wrong merge phase"); |
| G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::MergeLB, worker_id); |
| |
| G1MergeLogBufferCardsClosure cl(g1h, _scan_state); |
| g1h->iterate_dirty_card_closure(&cl, worker_id); |
| |
| p->record_thread_work_item(G1GCPhaseTimes::MergeLB, worker_id, cl.cards_dirty(), G1GCPhaseTimes::MergeLBDirtyCards); |
| p->record_thread_work_item(G1GCPhaseTimes::MergeLB, worker_id, cl.cards_skipped(), G1GCPhaseTimes::MergeLBSkippedCards); |
| } |
| } |
| }; |
| |
| void G1RemSet::print_merge_heap_roots_stats() { |
| size_t num_visited_cards = _scan_state->num_visited_cards(); |
| |
| size_t total_dirty_region_cards = _scan_state->num_cards_in_dirty_regions(); |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| size_t total_old_region_cards = |
| (g1h->num_regions() - (g1h->num_free_regions() - g1h->collection_set()->cur_length())) * HeapRegion::CardsPerRegion; |
| |
| log_debug(gc,remset)("Visited cards " SIZE_FORMAT " Total dirty " SIZE_FORMAT " (%.2lf%%) Total old " SIZE_FORMAT " (%.2lf%%)", |
| num_visited_cards, |
| total_dirty_region_cards, |
| percent_of(num_visited_cards, total_dirty_region_cards), |
| total_old_region_cards, |
| percent_of(num_visited_cards, total_old_region_cards)); |
| } |
| |
| void G1RemSet::merge_heap_roots(bool initial_evacuation) { |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| |
| { |
| Ticks start = Ticks::now(); |
| |
| _scan_state->prepare_for_merge_heap_roots(); |
| |
| Tickspan total = Ticks::now() - start; |
| if (initial_evacuation) { |
| g1h->phase_times()->record_prepare_merge_heap_roots_time(total.seconds() * 1000.0); |
| } else { |
| g1h->phase_times()->record_or_add_optional_prepare_merge_heap_roots_time(total.seconds() * 1000.0); |
| } |
| } |
| |
| WorkGang* workers = g1h->workers(); |
| size_t const increment_length = g1h->collection_set()->increment_length(); |
| |
| uint const num_workers = initial_evacuation ? workers->active_workers() : |
| MIN2(workers->active_workers(), (uint)increment_length); |
| |
| { |
| G1MergeHeapRootsTask cl(_scan_state, num_workers, initial_evacuation); |
| log_debug(gc, ergo)("Running %s using %u workers for " SIZE_FORMAT " regions", |
| cl.name(), num_workers, increment_length); |
| workers->run_task(&cl, num_workers); |
| } |
| |
| if (log_is_enabled(Debug, gc, remset)) { |
| print_merge_heap_roots_stats(); |
| } |
| } |
| |
| void G1RemSet::prepare_for_scan_heap_roots(uint region_idx) { |
| _scan_state->clear_scan_top(region_idx); |
| } |
| |
| void G1RemSet::cleanup_after_scan_heap_roots() { |
| G1GCPhaseTimes* phase_times = _g1h->phase_times(); |
| |
| // Set all cards back to clean. |
| double start = os::elapsedTime(); |
| _scan_state->cleanup(_g1h->workers()); |
| phase_times->record_clear_ct_time((os::elapsedTime() - start) * 1000.0); |
| } |
| |
| inline void check_card_ptr(CardTable::CardValue* card_ptr, G1CardTable* ct) { |
| #ifdef ASSERT |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| assert(g1h->is_in_exact(ct->addr_for(card_ptr)), |
| "Card at " PTR_FORMAT " index " SIZE_FORMAT " representing heap at " PTR_FORMAT " (%u) must be in committed heap", |
| p2i(card_ptr), |
| ct->index_for(ct->addr_for(card_ptr)), |
| p2i(ct->addr_for(card_ptr)), |
| g1h->addr_to_region(ct->addr_for(card_ptr))); |
| #endif |
| } |
| |
| void G1RemSet::refine_card_concurrently(CardValue* card_ptr, |
| uint worker_i) { |
| assert(!_g1h->is_gc_active(), "Only call concurrently"); |
| |
| // Construct the region representing the card. |
| HeapWord* start = _ct->addr_for(card_ptr); |
| // And find the region containing it. |
| HeapRegion* r = _g1h->heap_region_containing_or_null(start); |
| |
| // If this is a (stale) card into an uncommitted region, exit. |
| if (r == NULL) { |
| return; |
| } |
| |
| check_card_ptr(card_ptr, _ct); |
| |
| // If the card is no longer dirty, nothing to do. |
| if (*card_ptr != G1CardTable::dirty_card_val()) { |
| return; |
| } |
| |
| // This check is needed for some uncommon cases where we should |
| // ignore the card. |
| // |
| // The region could be young. Cards for young regions are |
| // distinctly marked (set to g1_young_gen), so the post-barrier will |
| // filter them out. However, that marking is performed |
| // concurrently. A write to a young object could occur before the |
| // card has been marked young, slipping past the filter. |
| // |
| // The card could be stale, because the region has been freed since |
| // the card was recorded. In this case the region type could be |
| // anything. If (still) free or (reallocated) young, just ignore |
| // it. If (reallocated) old or humongous, the later card trimming |
| // and additional checks in iteration may detect staleness. At |
| // worst, we end up processing a stale card unnecessarily. |
| // |
| // In the normal (non-stale) case, the synchronization between the |
| // enqueueing of the card and processing it here will have ensured |
| // we see the up-to-date region type here. |
| if (!r->is_old_or_humongous_or_archive()) { |
| return; |
| } |
| |
| // The result from the hot card cache insert call is either: |
| // * pointer to the current card |
| // (implying that the current card is not 'hot'), |
| // * null |
| // (meaning we had inserted the card ptr into the "hot" card cache, |
| // which had some headroom), |
| // * a pointer to a "hot" card that was evicted from the "hot" cache. |
| // |
| |
| if (_hot_card_cache->use_cache()) { |
| assert(!SafepointSynchronize::is_at_safepoint(), "sanity"); |
| |
| const CardValue* orig_card_ptr = card_ptr; |
| card_ptr = _hot_card_cache->insert(card_ptr); |
| if (card_ptr == NULL) { |
| // There was no eviction. Nothing to do. |
| return; |
| } else if (card_ptr != orig_card_ptr) { |
| // Original card was inserted and an old card was evicted. |
| start = _ct->addr_for(card_ptr); |
| r = _g1h->heap_region_containing(start); |
| |
| // Check whether the region formerly in the cache should be |
| // ignored, as discussed earlier for the original card. The |
| // region could have been freed while in the cache. |
| if (!r->is_old_or_humongous_or_archive()) { |
| return; |
| } |
| } // Else we still have the original card. |
| } |
| |
| // Trim the region designated by the card to what's been allocated |
| // in the region. The card could be stale, or the card could cover |
| // (part of) an object at the end of the allocated space and extend |
| // beyond the end of allocation. |
| |
| // Non-humongous objects are only allocated in the old-gen during |
| // GC, so if region is old then top is stable. Humongous object |
| // allocation sets top last; if top has not yet been set, this is |
| // a stale card and we'll end up with an empty intersection. If |
| // this is not a stale card, the synchronization between the |
| // enqueuing of the card and processing it here will have ensured |
| // we see the up-to-date top here. |
| HeapWord* scan_limit = r->top(); |
| |
| if (scan_limit <= start) { |
| // If the trimmed region is empty, the card must be stale. |
| return; |
| } |
| |
| // Okay to clean and process the card now. There are still some |
| // stale card cases that may be detected by iteration and dealt with |
| // as iteration failure. |
| *const_cast<volatile CardValue*>(card_ptr) = G1CardTable::clean_card_val(); |
| |
| // This fence serves two purposes. First, the card must be cleaned |
| // before processing the contents. Second, we can't proceed with |
| // processing until after the read of top, for synchronization with |
| // possibly concurrent humongous object allocation. It's okay that |
| // reading top and reading type were racy wrto each other. We need |
| // both set, in any order, to proceed. |
| OrderAccess::fence(); |
| |
| // Don't use addr_for(card_ptr + 1) which can ask for |
| // a card beyond the heap. |
| HeapWord* end = start + G1CardTable::card_size_in_words; |
| MemRegion dirty_region(start, MIN2(scan_limit, end)); |
| assert(!dirty_region.is_empty(), "sanity"); |
| |
| G1ConcurrentRefineOopClosure conc_refine_cl(_g1h, worker_i); |
| if (r->oops_on_memregion_seq_iterate_careful<false>(dirty_region, &conc_refine_cl) != NULL) { |
| _num_conc_refined_cards++; // Unsynchronized update, only used for logging. |
| return; |
| } |
| |
| // If unable to process the card then we encountered an unparsable |
| // part of the heap (e.g. a partially allocated object, so only |
| // temporarily a problem) while processing a stale card. Despite |
| // the card being stale, we can't simply ignore it, because we've |
| // already marked the card cleaned, so taken responsibility for |
| // ensuring the card gets scanned. |
| // |
| // However, the card might have gotten re-dirtied and re-enqueued |
| // while we worked. (In fact, it's pretty likely.) |
| if (*card_ptr == G1CardTable::dirty_card_val()) { |
| return; |
| } |
| |
| // Re-dirty the card and enqueue in the *shared* queue. Can't use |
| // the thread-local queue, because that might be the queue that is |
| // being processed by us; we could be a Java thread conscripted to |
| // perform refinement on our queue's current buffer. |
| *card_ptr = G1CardTable::dirty_card_val(); |
| G1BarrierSet::shared_dirty_card_queue().enqueue(card_ptr); |
| } |
| |
| void G1RemSet::print_periodic_summary_info(const char* header, uint period_count) { |
| if ((G1SummarizeRSetStatsPeriod > 0) && log_is_enabled(Trace, gc, remset) && |
| (period_count % G1SummarizeRSetStatsPeriod == 0)) { |
| |
| G1RemSetSummary current(this); |
| _prev_period_summary.subtract_from(¤t); |
| |
| Log(gc, remset) log; |
| log.trace("%s", header); |
| ResourceMark rm; |
| LogStream ls(log.trace()); |
| _prev_period_summary.print_on(&ls); |
| |
| _prev_period_summary.set(¤t); |
| } |
| } |
| |
| void G1RemSet::print_summary_info() { |
| Log(gc, remset, exit) log; |
| if (log.is_trace()) { |
| log.trace(" Cumulative RS summary"); |
| G1RemSetSummary current(this); |
| ResourceMark rm; |
| LogStream ls(log.trace()); |
| current.print_on(&ls); |
| } |
| } |
| |
| class G1RebuildRemSetTask: public AbstractGangTask { |
| // Aggregate the counting data that was constructed concurrently |
| // with marking. |
| class G1RebuildRemSetHeapRegionClosure : public HeapRegionClosure { |
| G1ConcurrentMark* _cm; |
| G1RebuildRemSetClosure _update_cl; |
| |
| // Applies _update_cl to the references of the given object, limiting objArrays |
| // to the given MemRegion. Returns the amount of words actually scanned. |
| size_t scan_for_references(oop const obj, MemRegion mr) { |
| size_t const obj_size = obj->size(); |
| // All non-objArrays and objArrays completely within the mr |
| // can be scanned without passing the mr. |
| if (!obj->is_objArray() || mr.contains(MemRegion((HeapWord*)obj, obj_size))) { |
| obj->oop_iterate(&_update_cl); |
| return obj_size; |
| } |
| // This path is for objArrays crossing the given MemRegion. Only scan the |
| // area within the MemRegion. |
| obj->oop_iterate(&_update_cl, mr); |
| return mr.intersection(MemRegion((HeapWord*)obj, obj_size)).word_size(); |
| } |
| |
| // A humongous object is live (with respect to the scanning) either |
| // a) it is marked on the bitmap as such |
| // b) its TARS is larger than TAMS, i.e. has been allocated during marking. |
| bool is_humongous_live(oop const humongous_obj, const G1CMBitMap* const bitmap, HeapWord* tams, HeapWord* tars) const { |
| return bitmap->is_marked(humongous_obj) || (tars > tams); |
| } |
| |
| // Iterator over the live objects within the given MemRegion. |
| class LiveObjIterator : public StackObj { |
| const G1CMBitMap* const _bitmap; |
| const HeapWord* _tams; |
| const MemRegion _mr; |
| HeapWord* _current; |
| |
| bool is_below_tams() const { |
| return _current < _tams; |
| } |
| |
| bool is_live(HeapWord* obj) const { |
| return !is_below_tams() || _bitmap->is_marked(obj); |
| } |
| |
| HeapWord* bitmap_limit() const { |
| return MIN2(const_cast<HeapWord*>(_tams), _mr.end()); |
| } |
| |
| void move_if_below_tams() { |
| if (is_below_tams() && has_next()) { |
| _current = _bitmap->get_next_marked_addr(_current, bitmap_limit()); |
| } |
| } |
| public: |
| LiveObjIterator(const G1CMBitMap* const bitmap, const HeapWord* tams, const MemRegion mr, HeapWord* first_oop_into_mr) : |
| _bitmap(bitmap), |
| _tams(tams), |
| _mr(mr), |
| _current(first_oop_into_mr) { |
| |
| assert(_current <= _mr.start(), |
| "First oop " PTR_FORMAT " should extend into mr [" PTR_FORMAT ", " PTR_FORMAT ")", |
| p2i(first_oop_into_mr), p2i(mr.start()), p2i(mr.end())); |
| |
| // Step to the next live object within the MemRegion if needed. |
| if (is_live(_current)) { |
| // Non-objArrays were scanned by the previous part of that region. |
| if (_current < mr.start() && !oop(_current)->is_objArray()) { |
| _current += oop(_current)->size(); |
| // We might have positioned _current on a non-live object. Reposition to the next |
| // live one if needed. |
| move_if_below_tams(); |
| } |
| } else { |
| // The object at _current can only be dead if below TAMS, so we can use the bitmap. |
| // immediately. |
| _current = _bitmap->get_next_marked_addr(_current, bitmap_limit()); |
| assert(_current == _mr.end() || is_live(_current), |
| "Current " PTR_FORMAT " should be live (%s) or beyond the end of the MemRegion (" PTR_FORMAT ")", |
| p2i(_current), BOOL_TO_STR(is_live(_current)), p2i(_mr.end())); |
| } |
| } |
| |
| void move_to_next() { |
| _current += next()->size(); |
| move_if_below_tams(); |
| } |
| |
| oop next() const { |
| oop result = oop(_current); |
| assert(is_live(_current), |
| "Object " PTR_FORMAT " must be live TAMS " PTR_FORMAT " below %d mr " PTR_FORMAT " " PTR_FORMAT " outside %d", |
| p2i(_current), p2i(_tams), _tams > _current, p2i(_mr.start()), p2i(_mr.end()), _mr.contains(result)); |
| return result; |
| } |
| |
| bool has_next() const { |
| return _current < _mr.end(); |
| } |
| }; |
| |
| // Rebuild remembered sets in the part of the region specified by mr and hr. |
| // Objects between the bottom of the region and the TAMS are checked for liveness |
| // using the given bitmap. Objects between TAMS and TARS are assumed to be live. |
| // Returns the number of live words between bottom and TAMS. |
| size_t rebuild_rem_set_in_region(const G1CMBitMap* const bitmap, |
| HeapWord* const top_at_mark_start, |
| HeapWord* const top_at_rebuild_start, |
| HeapRegion* hr, |
| MemRegion mr) { |
| size_t marked_words = 0; |
| |
| if (hr->is_humongous()) { |
| oop const humongous_obj = oop(hr->humongous_start_region()->bottom()); |
| if (is_humongous_live(humongous_obj, bitmap, top_at_mark_start, top_at_rebuild_start)) { |
| // We need to scan both [bottom, TAMS) and [TAMS, top_at_rebuild_start); |
| // however in case of humongous objects it is sufficient to scan the encompassing |
| // area (top_at_rebuild_start is always larger or equal to TAMS) as one of the |
| // two areas will be zero sized. I.e. TAMS is either |
| // the same as bottom or top(_at_rebuild_start). There is no way TAMS has a different |
| // value: this would mean that TAMS points somewhere into the object. |
| assert(hr->top() == top_at_mark_start || hr->top() == top_at_rebuild_start, |
| "More than one object in the humongous region?"); |
| humongous_obj->oop_iterate(&_update_cl, mr); |
| return top_at_mark_start != hr->bottom() ? mr.intersection(MemRegion((HeapWord*)humongous_obj, humongous_obj->size())).byte_size() : 0; |
| } else { |
| return 0; |
| } |
| } |
| |
| for (LiveObjIterator it(bitmap, top_at_mark_start, mr, hr->block_start(mr.start())); it.has_next(); it.move_to_next()) { |
| oop obj = it.next(); |
| size_t scanned_size = scan_for_references(obj, mr); |
| if ((HeapWord*)obj < top_at_mark_start) { |
| marked_words += scanned_size; |
| } |
| } |
| |
| return marked_words * HeapWordSize; |
| } |
| public: |
| G1RebuildRemSetHeapRegionClosure(G1CollectedHeap* g1h, |
| G1ConcurrentMark* cm, |
| uint worker_id) : |
| HeapRegionClosure(), |
| _cm(cm), |
| _update_cl(g1h, worker_id) { } |
| |
| bool do_heap_region(HeapRegion* hr) { |
| if (_cm->has_aborted()) { |
| return true; |
| } |
| |
| uint const region_idx = hr->hrm_index(); |
| DEBUG_ONLY(HeapWord* const top_at_rebuild_start_check = _cm->top_at_rebuild_start(region_idx);) |
| assert(top_at_rebuild_start_check == NULL || |
| top_at_rebuild_start_check > hr->bottom(), |
| "A TARS (" PTR_FORMAT ") == bottom() (" PTR_FORMAT ") indicates the old region %u is empty (%s)", |
| p2i(top_at_rebuild_start_check), p2i(hr->bottom()), region_idx, hr->get_type_str()); |
| |
| size_t total_marked_bytes = 0; |
| size_t const chunk_size_in_words = G1RebuildRemSetChunkSize / HeapWordSize; |
| |
| HeapWord* const top_at_mark_start = hr->prev_top_at_mark_start(); |
| |
| HeapWord* cur = hr->bottom(); |
| while (cur < hr->end()) { |
| // After every iteration (yield point) we need to check whether the region's |
| // TARS changed due to e.g. eager reclaim. |
| HeapWord* const top_at_rebuild_start = _cm->top_at_rebuild_start(region_idx); |
| if (top_at_rebuild_start == NULL) { |
| return false; |
| } |
| |
| MemRegion next_chunk = MemRegion(hr->bottom(), top_at_rebuild_start).intersection(MemRegion(cur, chunk_size_in_words)); |
| if (next_chunk.is_empty()) { |
| break; |
| } |
| |
| const Ticks start = Ticks::now(); |
| size_t marked_bytes = rebuild_rem_set_in_region(_cm->prev_mark_bitmap(), |
| top_at_mark_start, |
| top_at_rebuild_start, |
| hr, |
| next_chunk); |
| Tickspan time = Ticks::now() - start; |
| |
| log_trace(gc, remset, tracking)("Rebuilt region %u " |
| "live " SIZE_FORMAT " " |
| "time %.3fms " |
| "marked bytes " SIZE_FORMAT " " |
| "bot " PTR_FORMAT " " |
| "TAMS " PTR_FORMAT " " |
| "TARS " PTR_FORMAT, |
| region_idx, |
| _cm->liveness(region_idx) * HeapWordSize, |
| time.seconds() * 1000.0, |
| marked_bytes, |
| p2i(hr->bottom()), |
| p2i(top_at_mark_start), |
| p2i(top_at_rebuild_start)); |
| |
| if (marked_bytes > 0) { |
| total_marked_bytes += marked_bytes; |
| } |
| cur += chunk_size_in_words; |
| |
| _cm->do_yield_check(); |
| if (_cm->has_aborted()) { |
| return true; |
| } |
| } |
| // In the final iteration of the loop the region might have been eagerly reclaimed. |
| // Simply filter out those regions. We can not just use region type because there |
| // might have already been new allocations into these regions. |
| DEBUG_ONLY(HeapWord* const top_at_rebuild_start = _cm->top_at_rebuild_start(region_idx);) |
| assert(top_at_rebuild_start == NULL || |
| total_marked_bytes == hr->marked_bytes(), |
| "Marked bytes " SIZE_FORMAT " for region %u (%s) in [bottom, TAMS) do not match calculated marked bytes " SIZE_FORMAT " " |
| "(" PTR_FORMAT " " PTR_FORMAT " " PTR_FORMAT ")", |
| total_marked_bytes, hr->hrm_index(), hr->get_type_str(), hr->marked_bytes(), |
| p2i(hr->bottom()), p2i(top_at_mark_start), p2i(top_at_rebuild_start)); |
| // Abort state may have changed after the yield check. |
| return _cm->has_aborted(); |
| } |
| }; |
| |
| HeapRegionClaimer _hr_claimer; |
| G1ConcurrentMark* _cm; |
| |
| uint _worker_id_offset; |
| public: |
| G1RebuildRemSetTask(G1ConcurrentMark* cm, |
| uint n_workers, |
| uint worker_id_offset) : |
| AbstractGangTask("G1 Rebuild Remembered Set"), |
| _hr_claimer(n_workers), |
| _cm(cm), |
| _worker_id_offset(worker_id_offset) { |
| } |
| |
| void work(uint worker_id) { |
| SuspendibleThreadSetJoiner sts_join; |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| |
| G1RebuildRemSetHeapRegionClosure cl(g1h, _cm, _worker_id_offset + worker_id); |
| g1h->heap_region_par_iterate_from_worker_offset(&cl, &_hr_claimer, worker_id); |
| } |
| }; |
| |
| void G1RemSet::rebuild_rem_set(G1ConcurrentMark* cm, |
| WorkGang* workers, |
| uint worker_id_offset) { |
| uint num_workers = workers->active_workers(); |
| |
| G1RebuildRemSetTask cl(cm, |
| num_workers, |
| worker_id_offset); |
| workers->run_task(&cl, num_workers); |
| } |
