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