1 /*
2 * Copyright (c) 2013, 2018, 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/g1/g1CardCounts.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/shared/cardTableModRefBS.hpp"
29 #include "services/memTracker.hpp"
30 #include "utilities/copy.hpp"
31
32 void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
33 if (zero_filled) {
34 return;
35 }
36 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
37 _counts->clear_range(mr);
38 }
39
40 size_t G1CardCounts::compute_size(size_t mem_region_size_in_words) {
41 // We keep card counts for every card, so the size of the card counts table must
42 // be the same as the card table.
43 return G1CardTable::compute_size(mem_region_size_in_words);
44 }
45
46 size_t G1CardCounts::heap_map_factor() {
47 // See G1CardCounts::compute_size() why we reuse the card table value.
48 return G1CardTable::heap_map_factor();
49 }
50
51 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
52 if (has_count_table()) {
53 assert(from_card_num < to_card_num,
54 "Wrong order? from: " SIZE_FORMAT ", to: " SIZE_FORMAT,
55 from_card_num, to_card_num);
56 Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
57 }
58 }
59
60 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
61 _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) {
62 _listener.set_cardcounts(this);
63 }
64
65 void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) {
66 assert(_g1h->max_capacity() > 0, "initialization order");
67 assert(_g1h->capacity() == 0, "initialization order");
68
69 if (G1ConcRSHotCardLimit > 0) {
70 // The max value we can store in the counts table is
71 // max_jubyte. Guarantee the value of the hot
72 // threshold limit is no more than this.
73 guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");
74
75 _ct = _g1h->card_table();
76 _ct_bot = _ct->byte_for_const(_g1h->reserved_region().start());
77
78 _card_counts = (jubyte*) mapper->reserved().start();
79 _reserved_max_card_num = mapper->reserved().byte_size();
80 mapper->set_mapping_changed_listener(&_listener);
81 }
82 }
83
84 uint G1CardCounts::add_card_count(jbyte* card_ptr) {
85 // Returns the number of times the card has been refined.
86 // If we failed to reserve/commit the counts table, return 0.
87 // If card_ptr is beyond the committed end of the counts table,
88 // return 0.
89 // Otherwise return the actual count.
90 // Unless G1ConcRSHotCardLimit has been set appropriately,
91 // returning 0 will result in the card being considered
92 // cold and will be refined immediately.
93 uint count = 0;
94 if (has_count_table()) {
95 size_t card_num = ptr_2_card_num(card_ptr);
96 assert(card_num < _reserved_max_card_num,
97 "Card " SIZE_FORMAT " outside of card counts table (max size " SIZE_FORMAT ")",
98 card_num, _reserved_max_card_num);
99 count = (uint) _card_counts[card_num];
100 if (count < G1ConcRSHotCardLimit) {
101 _card_counts[card_num] =
102 (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
103 }
104 }
105 return count;
106 }
107
108 bool G1CardCounts::is_hot(uint count) {
109 return (count >= G1ConcRSHotCardLimit);
110 }
111
112 void G1CardCounts::clear_region(HeapRegion* hr) {
113 MemRegion mr(hr->bottom(), hr->end());
114 clear_range(mr);
115 }
116
117 void G1CardCounts::clear_range(MemRegion mr) {
118 if (has_count_table()) {
119 const jbyte* from_card_ptr = _ct->byte_for_const(mr.start());
120 // We use the last address in the range as the range could represent the
121 // last region in the heap. In which case trying to find the card will be an
122 // OOB access to the card table.
123 const jbyte* last_card_ptr = _ct->byte_for_const(mr.last());
124
125 #ifdef ASSERT
126 HeapWord* start_addr = _ct->addr_for(from_card_ptr);
127 assert(start_addr == mr.start(), "MemRegion start must be aligned to a card.");
128 HeapWord* last_addr = _ct->addr_for(last_card_ptr);
129 assert((last_addr + G1CardTable::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card.");
130 #endif // ASSERT
131
132 // Clear the counts for the (exclusive) card range.
133 size_t from_card_num = ptr_2_card_num(from_card_ptr);
134 size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;
135 clear_range(from_card_num, to_card_num);
136 }
137 }
138
139 class G1CardCountsClearClosure : public HeapRegionClosure {
140 private:
141 G1CardCounts* _card_counts;
142 public:
143 G1CardCountsClearClosure(G1CardCounts* card_counts) :
144 HeapRegionClosure(), _card_counts(card_counts) { }
145
146
147 virtual bool do_heap_region(HeapRegion* r) {
148 _card_counts->clear_region(r);
149 return false;
150 }
151 };
152
153 void G1CardCounts::clear_all() {
154 assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
155 G1CardCountsClearClosure cl(this);
156 _g1h->heap_region_iterate(&cl);
157 }