10246
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1 /*
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2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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24
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25 #include "precompiled.hpp"
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26 #include "gc_implementation/g1/dirtyCardQueue.hpp"
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27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
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28 #include "gc_implementation/g1/g1HotCardCache.hpp"
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29 #include "gc_implementation/g1/g1RemSet.hpp"
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30 #include "gc_implementation/g1/heapRegion.hpp"
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31 #include "runtime/atomic.hpp"
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32
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33 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
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34 _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
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35
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36 void G1HotCardCache::initialize() {
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37 if (default_use_cache()) {
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38 _use_cache = true;
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39
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40 _hot_cache_size = (1 << G1ConcRSLogCacheSize);
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41 _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
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42
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43 _n_hot = 0;
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44 _hot_cache_idx = 0;
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45
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46 // For refining the cards in the hot cache in parallel
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47 int n_workers = (ParallelGCThreads > 0 ?
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48 _g1h->workers()->total_workers() : 1);
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49 _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
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50 _hot_cache_par_claimed_idx = 0;
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51
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52 _card_counts.initialize();
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53 }
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54 }
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55
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56 G1HotCardCache::~G1HotCardCache() {
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57 if (default_use_cache()) {
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58 assert(_hot_cache != NULL, "Logic");
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59 FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
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60 }
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61 }
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62
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63 jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
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64 uint count = _card_counts.add_card_count(card_ptr);
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65 if (!_card_counts.is_hot(count)) {
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66 // The card is not hot so do not store it in the cache;
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67 // return it for immediate refining.
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68 return card_ptr;
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69 }
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70
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71 // Otherwise, the card is hot.
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72 jbyte* res = NULL;
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73 MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
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74 if (_n_hot == _hot_cache_size) {
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75 res = _hot_cache[_hot_cache_idx];
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76 _n_hot--;
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77 }
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78
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79 // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
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80 _hot_cache[_hot_cache_idx] = card_ptr;
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81 _hot_cache_idx++;
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82
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83 if (_hot_cache_idx == _hot_cache_size) {
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84 // Wrap around
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85 _hot_cache_idx = 0;
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86 }
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87 _n_hot++;
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88
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89 return res;
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90 }
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91
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92 void G1HotCardCache::drain(int worker_i,
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93 G1RemSet* g1rs,
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94 DirtyCardQueue* into_cset_dcq) {
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95 if (!default_use_cache()) {
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96 assert(_hot_cache == NULL, "Logic");
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97 return;
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98 }
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99
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100 assert(_hot_cache != NULL, "Logic");
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101 assert(!use_cache(), "cache should be disabled");
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102 int start_idx;
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103
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104 while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
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105 int end_idx = start_idx + _hot_cache_par_chunk_size;
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106
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107 if (start_idx ==
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108 Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
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109 // The current worker has successfully claimed the chunk [start_idx..end_idx)
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110 end_idx = MIN2(end_idx, _n_hot);
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111 for (int i = start_idx; i < end_idx; i++) {
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112 jbyte* card_ptr = _hot_cache[i];
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113 if (card_ptr != NULL) {
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114 if (g1rs->refine_card(card_ptr, worker_i, true)) {
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115 // The part of the heap spanned by the card contains references
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116 // that point into the current collection set.
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117 // We need to record the card pointer in the DirtyCardQueueSet
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118 // that we use for such cards.
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119 //
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120 // The only time we care about recording cards that contain
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121 // references that point into the collection set is during
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122 // RSet updating while within an evacuation pause.
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123 // In this case worker_i should be the id of a GC worker thread
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124 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
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125 assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads),
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126 err_msg("incorrect worker id: "INT32_FORMAT, worker_i));
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127
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128 into_cset_dcq->enqueue(card_ptr);
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129 }
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130 }
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131 }
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132 }
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133 }
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134 // The existing entries in the hot card cache, which were just refined
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135 // above, are discarded prior to re-enabling the cache near the end of the GC.
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136 }
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137
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138 void G1HotCardCache::resize_card_counts(size_t heap_capacity) {
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139 _card_counts.resize(heap_capacity);
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140 }
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141
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142 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
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143 _card_counts.clear_region(hr);
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144 }
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145
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146 void G1HotCardCache::reset_card_counts() {
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147 _card_counts.clear_all();
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148 }
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