Mercurial > hg > graal-jvmci-8
diff src/share/vm/gc_implementation/g1/g1HotCardCache.hpp @ 10246:194f52aa2f23
7176479: G1: JVM crashes on T5-8 system with 1.5 TB heap
Summary: Refactor G1's hot card cache and card counts table into their own files. Simplify the card counts table, including removing the encoding of the card index in each entry. The card counts table now has a 1:1 correspondence with the cards spanned by heap. Space for the card counts table is reserved from virtual memory (rather than C heap) during JVM startup and is committed/expanded when the heap is expanded. Changes were also reviewed-by Vitaly Davidovich.
Reviewed-by: tschatzl, jmasa
author | johnc |
---|---|
date | Thu, 09 May 2013 11:16:39 -0700 |
parents | |
children | 8847586c9037 |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1HotCardCache.hpp Thu May 09 11:16:39 2013 -0700 @@ -0,0 +1,128 @@ +/* + * Copyright (c) 2013, 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_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP + +#include "gc_implementation/g1/g1_globals.hpp" +#include "gc_implementation/g1/g1CardCounts.hpp" +#include "memory/allocation.hpp" +#include "runtime/safepoint.hpp" +#include "runtime/thread.inline.hpp" +#include "utilities/globalDefinitions.hpp" + +class DirtyCardQueue; +class G1CollectedHeap; +class G1RemSet; +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; + + // The card cache table + jbyte** _hot_cache; + + int _hot_cache_size; + int _n_hot; + int _hot_cache_idx; + + int _hot_cache_par_chunk_size; + volatile int _hot_cache_par_claimed_idx; + + bool _use_cache; + + G1CardCounts _card_counts; + + bool default_use_cache() const { + return (G1ConcRSLogCacheSize > 0); + } + + public: + G1HotCardCache(G1CollectedHeap* g1h); + ~G1HotCardCache(); + + void initialize(); + + 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(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq); + + // 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"); + _hot_cache_idx = 0; _n_hot = 0; + } + + bool hot_cache_is_empty() { return _n_hot == 0; } + + // Resizes the card counts table to match the given capacity + void resize_card_counts(size_t heap_capacity); + + // 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); +}; + +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP