1 /*
2 * Copyright (c) 2018, 2019, 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 #ifndef SHARE_MEMORY_METASPACE_CHUNKLEVEL_HPP
26 #define SHARE_MEMORY_METASPACE_CHUNKLEVEL_HPP
27
28 #include "utilities/globalDefinitions.hpp"
29
30 // Constants for the chunk levels and some utility functions.
31
32 namespace metaspace {
33
34 // Metachunk level (must be signed)
35 typedef signed char chklvl_t;
36
37 // Chunks are managed by a binary buddy allocator.
38
39 // Chunk sizes range from 1K to 4MB (64bit).
40 //
41 // Reasoning: .... TODO explain
42
43 // Each chunk has a level; the level corresponds to its position in the tree
44 // and describes its size.
45 //
46 // The largest chunks are called root chunks, of 4MB in size, and have level 0.
47 // From there on it goes:
48 //
49 // size level
50 // 4MB 0
51 // 2MB 1
52 // 1MB 2
53 // 512K 3
54 // 256K 4
55 // 128K 5
56 // 64K 6
57 // 32K 7
58 // 16K 8
59 // 8K 9
60 // 4K 10
61 // 2K 11
62 // 1K 12
63
64 namespace chklvl {
65
66 static const size_t MAX_CHUNK_BYTE_SIZE = 4 * M;
67 static const int NUM_CHUNK_LEVELS = 13;
68 static const size_t MIN_CHUNK_BYTE_SIZE = (MAX_CHUNK_BYTE_SIZE >> (size_t)NUM_CHUNK_LEVELS);
69
70 static const size_t MIN_CHUNK_WORD_SIZE = MIN_CHUNK_BYTE_SIZE / sizeof(MetaWord);
71 static const size_t MAX_CHUNK_WORD_SIZE = MAX_CHUNK_BYTE_SIZE / sizeof(MetaWord);
72
73 static const chklvl_t ROOT_CHUNK_LEVEL = 0;
74
75 static const chklvl_t HIGHEST_CHUNK_LEVEL = NUM_CHUNK_LEVELS - 1;
76 static const chklvl_t LOWEST_CHUNK_LEVEL = 0;
77
78 static const chklvl_t INVALID_CHUNK_LEVEL = (chklvl_t) -1;
79
80 inline bool is_valid_level(chklvl_t level) {
81 return level >= LOWEST_CHUNK_LEVEL &&
82 level <= HIGHEST_CHUNK_LEVEL;
83 }
84
85 inline void check_valid_level(chklvl_t lvl) {
86 assert(is_valid_level(lvl), "invalid level (%d)", (int)lvl);
87 }
88
89 // Given a level return the chunk size, in words.
90 inline size_t word_size_for_level(chklvl_t level) {
91 check_valid_level(level);
92 return MAX_CHUNK_BYTE_SIZE >> level;
93 }
94
95 // Given an arbitrary word size smaller than the highest chunk size,
96 // return the highest chunk level able to hold this size.
97 // Returns INVALID_CHUNK_LEVEL if no fitting level can be found.
98 chklvl_t level_fitting_word_size(size_t word_size);
99
100 // Shorthands to refer to exact sizes
101 static const chklvl_t CHUNK_LEVEL_4M = ROOT_CHUNK_LEVEL;
102 static const chklvl_t CHUNK_LEVEL_2M = (ROOT_CHUNK_LEVEL + 1);
103 static const chklvl_t CHUNK_LEVEL_1M = (ROOT_CHUNK_LEVEL + 2);
104 static const chklvl_t CHUNK_LEVEL_512K = (ROOT_CHUNK_LEVEL + 3);
105 static const chklvl_t CHUNK_LEVEL_256K = (ROOT_CHUNK_LEVEL + 4);
106 static const chklvl_t CHUNK_LEVEL_128K = (ROOT_CHUNK_LEVEL + 5);
107 static const chklvl_t CHUNK_LEVEL_64K = (ROOT_CHUNK_LEVEL + 6);
108 static const chklvl_t CHUNK_LEVEL_32K = (ROOT_CHUNK_LEVEL + 7);
109 static const chklvl_t CHUNK_LEVEL_16K = (ROOT_CHUNK_LEVEL + 8);
110 static const chklvl_t CHUNK_LEVEL_8K = (ROOT_CHUNK_LEVEL + 9);
111 static const chklvl_t CHUNK_LEVEL_4K = (ROOT_CHUNK_LEVEL + 10);
112 static const chklvl_t CHUNK_LEVEL_2K = (ROOT_CHUNK_LEVEL + 11);
113 static const chklvl_t CHUNK_LEVEL_1K = (ROOT_CHUNK_LEVEL + 12);
114
115 STATIC_ASSERT(CHUNK_LEVEL_1K == HIGHEST_CHUNK_LEVEL);
116
117
118 } // namespace chklvl
119
120 } // namespace metaspace
121
122 #endif // SHARE_MEMORY_METASPACE_BLOCKFREELIST_HPP