1 /*
2 * Copyright (c) 2013, 2014, 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 = ClaimChunkSize;
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);
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,
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 }