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 #include "precompiled.hpp" 26 #include "gc_implementation/g1/dirtyCardQueue.hpp" 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 28 #include "gc_implementation/g1/g1HotCardCache.hpp" 29 #include "gc_implementation/g1/g1RemSet.hpp" 30 #include "runtime/atomic.inline.hpp" 31 32 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h): 33 _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {} 34 35 void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) { 36 if (default_use_cache()) { 37 _use_cache = true; 38 39 _hot_cache_size = (1 << G1ConcRSLogCacheSize); 40 _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC); 41 42 _n_hot = 0; 43 _hot_cache_idx = 0; 44 45 // For refining the cards in the hot cache in parallel 46 _hot_cache_par_chunk_size = (ParallelGCThreads > 0 ? ClaimChunkSize : _hot_cache_size); 47 _hot_cache_par_claimed_idx = 0; 48 49 _card_counts.initialize(card_counts_storage); 50 } 51 } 52 53 G1HotCardCache::~G1HotCardCache() { 54 if (default_use_cache()) { 55 assert(_hot_cache != NULL, "Logic"); 56 FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC); 57 } 58 } 59 60 jbyte* G1HotCardCache::insert(jbyte* card_ptr) { 61 uint count = _card_counts.add_card_count(card_ptr); 62 if (!_card_counts.is_hot(count)) { 63 // The card is not hot so do not store it in the cache; 64 // return it for immediate refining. 65 return card_ptr; 66 } 67 68 // Otherwise, the card is hot. 69 jbyte* res = NULL; 70 MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag); 71 if (_n_hot == _hot_cache_size) { 72 res = _hot_cache[_hot_cache_idx]; 73 _n_hot--; 74 } 75 76 // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx. 77 _hot_cache[_hot_cache_idx] = card_ptr; 78 _hot_cache_idx++; 79 80 if (_hot_cache_idx == _hot_cache_size) { 81 // Wrap around 82 _hot_cache_idx = 0; 83 } 84 _n_hot++; 85 86 return res; 87 } 88 89 void G1HotCardCache::drain(uint worker_i, 90 G1RemSet* g1rs, 91 DirtyCardQueue* into_cset_dcq) { 92 if (!default_use_cache()) { 93 assert(_hot_cache == NULL, "Logic"); 94 return; 95 } 96 97 assert(_hot_cache != NULL, "Logic"); 98 assert(!use_cache(), "cache should be disabled"); 99 int start_idx; 100 101 while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once 102 int end_idx = start_idx + _hot_cache_par_chunk_size; 103 104 if (start_idx == 105 Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) { 106 // The current worker has successfully claimed the chunk [start_idx..end_idx) 107 end_idx = MIN2(end_idx, _n_hot); 108 for (int i = start_idx; i < end_idx; i++) { 109 jbyte* card_ptr = _hot_cache[i]; 110 if (card_ptr != NULL) { 111 if (g1rs->refine_card(card_ptr, worker_i, true)) { 112 // The part of the heap spanned by the card contains references 113 // that point into the current collection set. 114 // We need to record the card pointer in the DirtyCardQueueSet 115 // that we use for such cards. 116 // 117 // The only time we care about recording cards that contain 118 // references that point into the collection set is during 119 // RSet updating while within an evacuation pause. 120 // In this case worker_i should be the id of a GC worker thread 121 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint"); 122 assert(worker_i < (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), 123 err_msg("incorrect worker id: %u", worker_i)); 124 125 into_cset_dcq->enqueue(card_ptr); 126 } 127 } 128 } 129 } 130 } 131 // The existing entries in the hot card cache, which were just refined 132 // above, are discarded prior to re-enabling the cache near the end of the GC. 133 } 134 135 void G1HotCardCache::reset_card_counts(HeapRegion* hr) { 136 _card_counts.clear_region(hr); 137 } 138 139 void G1HotCardCache::reset_card_counts() { 140 _card_counts.clear_all(); 141 }