123 lines
4.6 KiB
C++
123 lines
4.6 KiB
C++
/*
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* Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "gc/g1/g1CardTableEntryClosure.hpp"
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#include "gc/g1/g1CollectedHeap.inline.hpp"
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#include "gc/g1/g1DirtyCardQueue.hpp"
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#include "gc/g1/g1HotCardCache.hpp"
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#include "runtime/atomic.hpp"
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G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
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_g1h(g1h), _use_cache(false), _card_counts(g1h),
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_hot_cache(NULL), _hot_cache_size(0), _hot_cache_par_chunk_size(0),
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_hot_cache_idx(0), _hot_cache_par_claimed_idx(0), _cache_wrapped_around(false)
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{}
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void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {
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if (default_use_cache()) {
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_use_cache = true;
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_hot_cache_size = (size_t)1 << G1ConcRSLogCacheSize;
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_hot_cache = ArrayAllocator<CardValue*>::allocate(_hot_cache_size, mtGC);
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reset_hot_cache_internal();
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// For refining the cards in the hot cache in parallel
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_hot_cache_par_chunk_size = ClaimChunkSize;
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_hot_cache_par_claimed_idx = 0;
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_cache_wrapped_around = false;
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_card_counts.initialize(card_counts_storage);
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}
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}
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G1HotCardCache::~G1HotCardCache() {
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if (default_use_cache()) {
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assert(_hot_cache != NULL, "Logic");
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ArrayAllocator<CardValue*>::free(_hot_cache, _hot_cache_size);
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_hot_cache = NULL;
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}
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}
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CardTable::CardValue* G1HotCardCache::insert(CardValue* card_ptr) {
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uint count = _card_counts.add_card_count(card_ptr);
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if (!_card_counts.is_hot(count)) {
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// The card is not hot so do not store it in the cache;
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// return it for immediate refining.
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return card_ptr;
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}
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// Otherwise, the card is hot.
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size_t index = Atomic::fetch_and_add(&_hot_cache_idx, 1u);
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if (index == _hot_cache_size) {
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// Can use relaxed store because all racing threads are writing the same
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// value and there aren't any concurrent readers.
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Atomic::store(&_cache_wrapped_around, true);
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}
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size_t masked_index = index & (_hot_cache_size - 1);
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CardValue* current_ptr = _hot_cache[masked_index];
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// Try to store the new card pointer into the cache. Compare-and-swap to guard
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// against the unlikely event of a race resulting in another card pointer to
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// have already been written to the cache. In this case we will return
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// card_ptr in favor of the other option, which would be starting over. This
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// should be OK since card_ptr will likely be the older card already when/if
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// this ever happens.
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CardValue* previous_ptr = Atomic::cmpxchg(&_hot_cache[masked_index],
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current_ptr,
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card_ptr);
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return (previous_ptr == current_ptr) ? previous_ptr : card_ptr;
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}
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void G1HotCardCache::drain(G1CardTableEntryClosure* cl, uint worker_id) {
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assert(default_use_cache(), "Drain only necessary if we use the hot card cache.");
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assert(_hot_cache != NULL, "Logic");
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assert(!use_cache(), "cache should be disabled");
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while (_hot_cache_par_claimed_idx < _hot_cache_size) {
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size_t end_idx = Atomic::add(&_hot_cache_par_claimed_idx,
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_hot_cache_par_chunk_size);
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size_t start_idx = end_idx - _hot_cache_par_chunk_size;
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// The current worker has successfully claimed the chunk [start_idx..end_idx)
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end_idx = MIN2(end_idx, _hot_cache_size);
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for (size_t i = start_idx; i < end_idx; i++) {
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CardValue* card_ptr = _hot_cache[i];
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if (card_ptr != NULL) {
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cl->do_card_ptr(card_ptr, worker_id);
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} else {
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break;
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}
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}
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}
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// The existing entries in the hot card cache, which were just refined
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// above, are discarded prior to re-enabling the cache near the end of the GC.
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}
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void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
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_card_counts.clear_region(hr);
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}
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