1 /*
2 * Copyright (c) 2001, 2010, 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/parallelScavenge/objectStartArray.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/cardTableModRefBS.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/java.hpp"
31
32 void ObjectStartArray::initialize(MemRegion reserved_region) {
33 // We're based on the assumption that we use the same
34 // size blocks as the card table.
35 assert((int)block_size == (int)CardTableModRefBS::card_size, "Sanity");
36 assert((int)block_size <= 512, "block_size must be less than or equal to 512");
37
38 // Calculate how much space must be reserved
39 _reserved_region = reserved_region;
40
41 size_t bytes_to_reserve = reserved_region.word_size() / block_size_in_words;
42 assert(bytes_to_reserve > 0, "Sanity");
43
44 bytes_to_reserve =
45 align_size_up(bytes_to_reserve, os::vm_allocation_granularity());
46
47 // Do not use large-pages for the backing store. The one large page region
48 // will be used for the heap proper.
49 ReservedSpace backing_store(bytes_to_reserve);
50 if (!backing_store.is_reserved()) {
51 vm_exit_during_initialization("Could not reserve space for ObjectStartArray");
52 }
53
54 // We do not commit any memory initially
55 if (!_virtual_space.initialize(backing_store, 0)) {
56 vm_exit_during_initialization("Could not commit space for ObjectStartArray");
57 }
58
59 _raw_base = (jbyte*)_virtual_space.low_boundary();
60 if (_raw_base == NULL) {
61 vm_exit_during_initialization("Could not get raw_base address");
62 }
63
64 _offset_base = _raw_base - (size_t(reserved_region.start()) >> block_shift);
65
66 _covered_region.set_start(reserved_region.start());
67 _covered_region.set_word_size(0);
68
69 _blocks_region.set_start((HeapWord*)_raw_base);
70 _blocks_region.set_word_size(0);
71 }
72
73 void ObjectStartArray::set_covered_region(MemRegion mr) {
74 assert(_reserved_region.contains(mr), "MemRegion outside of reserved space");
75 assert(_reserved_region.start() == mr.start(), "Attempt to move covered region");
76
77 HeapWord* low_bound = mr.start();
78 HeapWord* high_bound = mr.end();
79 assert((uintptr_t(low_bound) & (block_size - 1)) == 0, "heap must start at block boundary");
80 assert((uintptr_t(high_bound) & (block_size - 1)) == 0, "heap must end at block boundary");
81
82 size_t requested_blocks_size_in_bytes = mr.word_size() / block_size_in_words;
83
84 // Only commit memory in page sized chunks
85 requested_blocks_size_in_bytes =
86 align_size_up(requested_blocks_size_in_bytes, os::vm_page_size());
87
88 _covered_region = mr;
89
90 size_t current_blocks_size_in_bytes = _blocks_region.byte_size();
91
92 if (requested_blocks_size_in_bytes > current_blocks_size_in_bytes) {
93 // Expand
94 size_t expand_by = requested_blocks_size_in_bytes - current_blocks_size_in_bytes;
95 if (!_virtual_space.expand_by(expand_by)) {
96 vm_exit_out_of_memory(expand_by, "object start array expansion");
97 }
98 // Clear *only* the newly allocated region
99 memset(_blocks_region.end(), clean_block, expand_by);
100 }
101
102 if (requested_blocks_size_in_bytes < current_blocks_size_in_bytes) {
103 // Shrink
104 size_t shrink_by = current_blocks_size_in_bytes - requested_blocks_size_in_bytes;
105 _virtual_space.shrink_by(shrink_by);
106 }
107
108 _blocks_region.set_word_size(requested_blocks_size_in_bytes / sizeof(HeapWord));
109
110 assert(requested_blocks_size_in_bytes % sizeof(HeapWord) == 0, "Block table not expanded in word sized increment");
111 assert(requested_blocks_size_in_bytes == _blocks_region.byte_size(), "Sanity");
112 assert(block_for_addr(low_bound) == &_raw_base[0], "Checking start of map");
113 assert(block_for_addr(high_bound-1) <= &_raw_base[_blocks_region.byte_size()-1], "Checking end of map");
114 }
115
116 void ObjectStartArray::reset() {
117 memset(_blocks_region.start(), clean_block, _blocks_region.byte_size());
118 }
119
120
121 bool ObjectStartArray::object_starts_in_range(HeapWord* start_addr,
122 HeapWord* end_addr) const {
123 assert(start_addr <= end_addr, "range is wrong");
124 if (start_addr > end_addr) {
125 return false;
126 }
127
128 jbyte* start_block = block_for_addr(start_addr);
129 jbyte* end_block = block_for_addr(end_addr);
130
131 for (jbyte* block = start_block; block <= end_block; block++) {
132 if (*block != clean_block) {
133 return true;
134 }
135 }
136 // No object starts in this slice; verify this using
137 // more traditional methods:
138 assert(object_start(end_addr - 1) <= start_addr,
139 "Oops an object does start in this slice?");
140 return false;
141 }