johnc@5078: /*
johnc@5078:  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
johnc@5078:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
johnc@5078:  *
johnc@5078:  * This code is free software; you can redistribute it and/or modify it
johnc@5078:  * under the terms of the GNU General Public License version 2 only, as
johnc@5078:  * published by the Free Software Foundation.
johnc@5078:  *
johnc@5078:  * This code is distributed in the hope that it will be useful, but WITHOUT
johnc@5078:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
johnc@5078:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
johnc@5078:  * version 2 for more details (a copy is included in the LICENSE file that
johnc@5078:  * accompanied this code).
johnc@5078:  *
johnc@5078:  * You should have received a copy of the GNU General Public License version
johnc@5078:  * 2 along with this work; if not, write to the Free Software Foundation,
johnc@5078:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
johnc@5078:  *
johnc@5078:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
johnc@5078:  * or visit www.oracle.com if you need additional information or have any
johnc@5078:  * questions.
johnc@5078:  *
johnc@5078:  */
johnc@5078: 
johnc@5078: #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
johnc@5078: #define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
johnc@5078: 
johnc@5078: #include "gc_implementation/g1/g1_globals.hpp"
johnc@5078: #include "gc_implementation/g1/g1CardCounts.hpp"
johnc@5078: #include "memory/allocation.hpp"
johnc@5078: #include "runtime/safepoint.hpp"
johnc@5078: #include "runtime/thread.inline.hpp"
johnc@5078: #include "utilities/globalDefinitions.hpp"
johnc@5078: 
johnc@5078: class DirtyCardQueue;
johnc@5078: class G1CollectedHeap;
johnc@5078: class G1RemSet;
johnc@5078: class HeapRegion;
johnc@5078: 
johnc@5078: // An evicting cache of cards that have been logged by the G1 post
johnc@5078: // write barrier. Placing a card in the cache delays the refinement
johnc@5078: // of the card until the card is evicted, or the cache is drained
johnc@5078: // during the next evacuation pause.
johnc@5078: //
johnc@5078: // The first thing the G1 post write barrier does is to check whether
johnc@5078: // the card containing the updated pointer is already dirty and, if
johnc@5078: // so, skips the remaining code in the barrier.
johnc@5078: //
johnc@5078: // Delaying the refinement of a card will make the card fail the
johnc@5078: // first is_dirty check in the write barrier, skipping the remainder
johnc@5078: // of the write barrier.
johnc@5078: //
johnc@5078: // This can significantly reduce the overhead of the write barrier
johnc@5078: // code, increasing throughput.
johnc@5078: 
johnc@5078: class G1HotCardCache: public CHeapObj<mtGC> {
johnc@5078:   G1CollectedHeap*   _g1h;
johnc@5078: 
johnc@5078:   // The card cache table
johnc@5078:   jbyte**      _hot_cache;
johnc@5078: 
johnc@5078:   int          _hot_cache_size;
johnc@5078:   int          _n_hot;
johnc@5078:   int          _hot_cache_idx;
johnc@5078: 
johnc@5078:   int          _hot_cache_par_chunk_size;
johnc@5078:   volatile int _hot_cache_par_claimed_idx;
johnc@5078: 
johnc@5078:   bool         _use_cache;
johnc@5078: 
johnc@5078:   G1CardCounts _card_counts;
johnc@5078: 
johnc@5078:   bool default_use_cache() const {
johnc@5078:     return (G1ConcRSLogCacheSize > 0);
johnc@5078:   }
johnc@5078: 
johnc@5078:  public:
johnc@5078:   G1HotCardCache(G1CollectedHeap* g1h);
johnc@5078:   ~G1HotCardCache();
johnc@5078: 
johnc@5078:   void initialize();
johnc@5078: 
johnc@5078:   bool use_cache() { return _use_cache; }
johnc@5078: 
johnc@5078:   void set_use_cache(bool b) {
johnc@5078:     _use_cache = (b ? default_use_cache() : false);
johnc@5078:   }
johnc@5078: 
johnc@5078:   // Returns the card to be refined or NULL.
johnc@5078:   //
johnc@5078:   // Increments the count for given the card. if the card is not 'hot',
johnc@5078:   // it is returned for immediate refining. Otherwise the card is
johnc@5078:   // added to the hot card cache.
johnc@5078:   // If there is enough room in the hot card cache for the card we're
johnc@5078:   // adding, NULL is returned and no further action in needed.
johnc@5078:   // If we evict a card from the cache to make room for the new card,
johnc@5078:   // the evicted card is then returned for refinement.
johnc@5078:   jbyte* insert(jbyte* card_ptr);
johnc@5078: 
johnc@5078:   // Refine the cards that have delayed as a result of
johnc@5078:   // being in the cache.
johnc@5078:   void drain(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
johnc@5078: 
johnc@5078:   // Set up for parallel processing of the cards in the hot cache
johnc@5078:   void reset_hot_cache_claimed_index() {
johnc@5078:     _hot_cache_par_claimed_idx = 0;
johnc@5078:   }
johnc@5078: 
johnc@5078:   // Resets the hot card cache and discards the entries.
johnc@5078:   void reset_hot_cache() {
johnc@5078:     assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
johnc@5078:     assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread");
johnc@5078:     _hot_cache_idx = 0; _n_hot = 0;
johnc@5078:   }
johnc@5078: 
johnc@5078:   bool hot_cache_is_empty() { return _n_hot == 0; }
johnc@5078: 
johnc@5078:   // Resizes the card counts table to match the given capacity
johnc@5078:   void resize_card_counts(size_t heap_capacity);
johnc@5078: 
johnc@5078:   // Zeros the values in the card counts table for entire committed heap
johnc@5078:   void reset_card_counts();
johnc@5078: 
johnc@5078:   // Zeros the values in the card counts table for the given region
johnc@5078:   void reset_card_counts(HeapRegion* hr);
johnc@5078: };
johnc@5078: 
johnc@5078: #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP