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 "gc_implementation/g1/heapRegion.hpp"
31 #include "runtime/atomic.hpp"
32
33 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
34 _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
35
36 void G1HotCardCache::initialize() {
37 if (default_use_cache()) {
38 _use_cache = true;
39
40 _hot_cache_size = (1 << G1ConcRSLogCacheSize);
41 _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
42
43 _n_hot = 0;
44 _hot_cache_idx = 0;
45
46 // For refining the cards in the hot cache in parallel
47 int n_workers = (ParallelGCThreads > 0 ?
48 _g1h->workers()->total_workers() : 1);
49 _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
50 _hot_cache_par_claimed_idx = 0;
51
52 _card_counts.initialize();
53 }
54 }
55
56 G1HotCardCache::~G1HotCardCache() {
57 if (default_use_cache()) {
58 assert(_hot_cache != NULL, "Logic");
59 FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
60 }
61 }
62
63 jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
64 uint count = _card_counts.add_card_count(card_ptr);
65 if (!_card_counts.is_hot(count)) {
66 // The card is not hot so do not store it in the cache;
67 // return it for immediate refining.
68 return card_ptr;
69 }
70
71 // Otherwise, the card is hot.
72 jbyte* res = NULL;
73 MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
74 if (_n_hot == _hot_cache_size) {
75 res = _hot_cache[_hot_cache_idx];
76 _n_hot--;
77 }
78
79 // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
80 _hot_cache[_hot_cache_idx] = card_ptr;
81 _hot_cache_idx++;
82
83 if (_hot_cache_idx == _hot_cache_size) {
84 // Wrap around
85 _hot_cache_idx = 0;
86 }
87 _n_hot++;
88
89 return res;
90 }
91
92 void G1HotCardCache::drain(int worker_i,
93 G1RemSet* g1rs,
94 DirtyCardQueue* into_cset_dcq) {
95 if (!default_use_cache()) {
96 assert(_hot_cache == NULL, "Logic");
97 return;
98 }
99
100 assert(_hot_cache != NULL, "Logic");
101 assert(!use_cache(), "cache should be disabled");
102 int start_idx;
103
104 while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
105 int end_idx = start_idx + _hot_cache_par_chunk_size;
106
107 if (start_idx ==
108 Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
109 // The current worker has successfully claimed the chunk [start_idx..end_idx)
110 end_idx = MIN2(end_idx, _n_hot);
111 for (int i = start_idx; i < end_idx; i++) {
112 jbyte* card_ptr = _hot_cache[i];
113 if (card_ptr != NULL) {
114 if (g1rs->refine_card(card_ptr, worker_i, true)) {
115 // The part of the heap spanned by the card contains references
116 // that point into the current collection set.
117 // We need to record the card pointer in the DirtyCardQueueSet
118 // that we use for such cards.
119 //
120 // The only time we care about recording cards that contain
121 // references that point into the collection set is during
122 // RSet updating while within an evacuation pause.
123 // In this case worker_i should be the id of a GC worker thread
124 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
125 assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads),
126 err_msg("incorrect worker id: "INT32_FORMAT, worker_i));
127
128 into_cset_dcq->enqueue(card_ptr);
129 }
130 }
131 }
132 }
133 }
134 // The existing entries in the hot card cache, which were just refined
135 // above, are discarded prior to re-enabling the cache near the end of the GC.
136 }
137
138 void G1HotCardCache::resize_card_counts(size_t heap_capacity) {
139 _card_counts.resize(heap_capacity);
140 }
141
142 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
143 _card_counts.clear_region(hr);
144 }
145
146 void G1HotCardCache::reset_card_counts() {
147 _card_counts.clear_all();
148 }