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comparison src/share/vm/gc_implementation/g1/g1HotCardCache.hpp @ 10246:194f52aa2f23

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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
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children 8847586c9037
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10245:923ac8d1df95 10246:194f52aa2f23
1 /*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
27
28 #include "gc_implementation/g1/g1_globals.hpp"
29 #include "gc_implementation/g1/g1CardCounts.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/safepoint.hpp"
32 #include "runtime/thread.inline.hpp"
33 #include "utilities/globalDefinitions.hpp"
34
35 class DirtyCardQueue;
36 class G1CollectedHeap;
37 class G1RemSet;
38 class HeapRegion;
39
40 // An evicting cache of cards that have been logged by the G1 post
41 // write barrier. Placing a card in the cache delays the refinement
42 // of the card until the card is evicted, or the cache is drained
43 // during the next evacuation pause.
44 //
45 // The first thing the G1 post write barrier does is to check whether
46 // the card containing the updated pointer is already dirty and, if
47 // so, skips the remaining code in the barrier.
48 //
49 // Delaying the refinement of a card will make the card fail the
50 // first is_dirty check in the write barrier, skipping the remainder
51 // of the write barrier.
52 //
53 // This can significantly reduce the overhead of the write barrier
54 // code, increasing throughput.
55
56 class G1HotCardCache: public CHeapObj<mtGC> {
57 G1CollectedHeap* _g1h;
58
59 // The card cache table
60 jbyte** _hot_cache;
61
62 int _hot_cache_size;
63 int _n_hot;
64 int _hot_cache_idx;
65
66 int _hot_cache_par_chunk_size;
67 volatile int _hot_cache_par_claimed_idx;
68
69 bool _use_cache;
70
71 G1CardCounts _card_counts;
72
73 bool default_use_cache() const {
74 return (G1ConcRSLogCacheSize > 0);
75 }
76
77 public:
78 G1HotCardCache(G1CollectedHeap* g1h);
79 ~G1HotCardCache();
80
81 void initialize();
82
83 bool use_cache() { return _use_cache; }
84
85 void set_use_cache(bool b) {
86 _use_cache = (b ? default_use_cache() : false);
87 }
88
89 // Returns the card to be refined or NULL.
90 //
91 // Increments the count for given the card. if the card is not 'hot',
92 // it is returned for immediate refining. Otherwise the card is
93 // added to the hot card cache.
94 // If there is enough room in the hot card cache for the card we're
95 // adding, NULL is returned and no further action in needed.
96 // If we evict a card from the cache to make room for the new card,
97 // the evicted card is then returned for refinement.
98 jbyte* insert(jbyte* card_ptr);
99
100 // Refine the cards that have delayed as a result of
101 // being in the cache.
102 void drain(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
103
104 // Set up for parallel processing of the cards in the hot cache
105 void reset_hot_cache_claimed_index() {
106 _hot_cache_par_claimed_idx = 0;
107 }
108
109 // Resets the hot card cache and discards the entries.
110 void reset_hot_cache() {
111 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
112 assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread");
113 _hot_cache_idx = 0; _n_hot = 0;
114 }
115
116 bool hot_cache_is_empty() { return _n_hot == 0; }
117
118 // Resizes the card counts table to match the given capacity
119 void resize_card_counts(size_t heap_capacity);
120
121 // Zeros the values in the card counts table for entire committed heap
122 void reset_card_counts();
123
124 // Zeros the values in the card counts table for the given region
125 void reset_card_counts(HeapRegion* hr);
126 };
127
128 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP