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comparison src/share/vm/memory/metablock.cpp @ 7208:eade6b2e4782

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8003554: NPG: move Metablock and Metachunk code out of metaspace.cpp Reviewed-by: coleenp
author jmasa
date Thu, 29 Nov 2012 10:09:04 -0800
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children 3efdfd6ddbf2
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7207:0f80645e9c26 7208:eade6b2e4782
1 /*
2 * Copyright (c) 2012, 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 "memory/allocation.hpp"
27 #include "memory/metablock.hpp"
28 #include "utilities/copy.hpp"
29 #include "utilities/debug.hpp"
30
31 // Blocks of space for metadata are allocated out of Metachunks.
32 //
33 // Metachunk are allocated out of MetadataVirtualspaces and once
34 // allocated there is no explicit link between a Metachunk and
35 // the MetadataVirtualspaces from which it was allocated.
36 //
37 // Each SpaceManager maintains a
38 // list of the chunks it is using and the current chunk. The current
39 // chunk is the chunk from which allocations are done. Space freed in
40 // a chunk is placed on the free list of blocks (BlockFreelist) and
41 // reused from there.
42 //
43 // Future modification
44 //
45 // The Metachunk can conceivable be replaced by the Chunk in
46 // allocation.hpp. Note that the latter Chunk is the space for
47 // allocation (allocations from the chunk are out of the space in
48 // the Chunk after the header for the Chunk) where as Metachunks
49 // point to space in a VirtualSpace. To replace Metachunks with
50 // Chunks, change Chunks so that they can be allocated out of a VirtualSpace.
51 size_t Metablock::_min_block_byte_size = sizeof(Metablock);
52
53 #ifdef ASSERT
54 size_t Metablock::_overhead =
55 Chunk::aligned_overhead_size(sizeof(Metablock)) / BytesPerWord;
56 #else
57 size_t Metablock::_overhead = 0;
58 #endif
59
60 // New blocks returned by the Metaspace are zero initialized.
61 // We should fix the constructors to not assume this instead.
62 Metablock* Metablock::initialize(MetaWord* p, size_t word_size) {
63 if (p == NULL) {
64 return NULL;
65 }
66
67 Metablock* result = (Metablock*) p;
68
69 // Clear the memory
70 Copy::fill_to_aligned_words((HeapWord*)result, word_size);
71 #ifdef ASSERT
72 result->set_word_size(word_size);
73 #endif
74 return result;
75 }