| /* |
| * Copyright (c) 2013, 2017, 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. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_G1_G1HOTCARDCACHE_HPP |
| #define SHARE_VM_GC_G1_G1HOTCARDCACHE_HPP |
| |
| #include "gc/g1/g1CardCounts.hpp" |
| #include "gc/g1/g1_globals.hpp" |
| #include "memory/allocation.hpp" |
| #include "runtime/safepoint.hpp" |
| #include "runtime/thread.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| |
| class CardTableEntryClosure; |
| class DirtyCardQueue; |
| class G1CollectedHeap; |
| class HeapRegion; |
| |
| // An evicting cache of cards that have been logged by the G1 post |
| // write barrier. Placing a card in the cache delays the refinement |
| // of the card until the card is evicted, or the cache is drained |
| // during the next evacuation pause. |
| // |
| // The first thing the G1 post write barrier does is to check whether |
| // the card containing the updated pointer is already dirty and, if |
| // so, skips the remaining code in the barrier. |
| // |
| // Delaying the refinement of a card will make the card fail the |
| // first is_dirty check in the write barrier, skipping the remainder |
| // of the write barrier. |
| // |
| // This can significantly reduce the overhead of the write barrier |
| // code, increasing throughput. |
| |
| class G1HotCardCache: public CHeapObj<mtGC> { |
| |
| G1CollectedHeap* _g1h; |
| |
| bool _use_cache; |
| |
| G1CardCounts _card_counts; |
| |
| |
| // The card cache table |
| jbyte** _hot_cache; |
| |
| size_t _hot_cache_size; |
| |
| size_t _hot_cache_par_chunk_size; |
| |
| // Avoids false sharing when concurrently updating _hot_cache_idx or |
| // _hot_cache_par_claimed_idx. These are never updated at the same time |
| // thus it's not necessary to separate them as well |
| char _pad_before[DEFAULT_CACHE_LINE_SIZE]; |
| |
| volatile size_t _hot_cache_idx; |
| |
| volatile size_t _hot_cache_par_claimed_idx; |
| |
| char _pad_after[DEFAULT_CACHE_LINE_SIZE]; |
| |
| // The number of cached cards a thread claims when flushing the cache |
| static const int ClaimChunkSize = 32; |
| |
| public: |
| static bool default_use_cache() { |
| return (G1ConcRSLogCacheSize > 0); |
| } |
| |
| G1HotCardCache(G1CollectedHeap* g1h); |
| ~G1HotCardCache(); |
| |
| void initialize(G1RegionToSpaceMapper* card_counts_storage); |
| |
| bool use_cache() { return _use_cache; } |
| |
| void set_use_cache(bool b) { |
| _use_cache = (b ? default_use_cache() : false); |
| } |
| |
| // Returns the card to be refined or NULL. |
| // |
| // Increments the count for given the card. if the card is not 'hot', |
| // it is returned for immediate refining. Otherwise the card is |
| // added to the hot card cache. |
| // If there is enough room in the hot card cache for the card we're |
| // adding, NULL is returned and no further action in needed. |
| // If we evict a card from the cache to make room for the new card, |
| // the evicted card is then returned for refinement. |
| jbyte* insert(jbyte* card_ptr); |
| |
| // Refine the cards that have delayed as a result of |
| // being in the cache. |
| void drain(CardTableEntryClosure* cl, uint worker_i); |
| |
| // Set up for parallel processing of the cards in the hot cache |
| void reset_hot_cache_claimed_index() { |
| _hot_cache_par_claimed_idx = 0; |
| } |
| |
| // Resets the hot card cache and discards the entries. |
| void reset_hot_cache() { |
| assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint"); |
| assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread"); |
| if (default_use_cache()) { |
| reset_hot_cache_internal(); |
| } |
| } |
| |
| // Zeros the values in the card counts table for entire committed heap |
| void reset_card_counts(); |
| |
| // Zeros the values in the card counts table for the given region |
| void reset_card_counts(HeapRegion* hr); |
| |
| private: |
| void reset_hot_cache_internal() { |
| assert(_hot_cache != NULL, "Logic"); |
| _hot_cache_idx = 0; |
| for (size_t i = 0; i < _hot_cache_size; i++) { |
| _hot_cache[i] = NULL; |
| } |
| } |
| }; |
| |
| #endif // SHARE_VM_GC_G1_G1HOTCARDCACHE_HPP |