Mercurial > hg > truffle
comparison src/share/vm/memory/padded.hpp @ 12029:9766f73e770d
8022880: False sharing between PSPromotionManager instances
Summary: Pad the PSPromotionManager instances in the manager array.
Reviewed-by: brutisso, jmasa
author | stefank |
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date | Fri, 31 May 2013 14:32:44 +0200 |
parents | |
children | d7070f371770 |
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12009:39127bb12d32 | 12029:9766f73e770d |
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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 #ifndef SHARE_VM_MEMORY_PADDED_HPP | |
26 #define SHARE_VM_MEMORY_PADDED_HPP | |
27 | |
28 #include "memory/allocation.hpp" | |
29 #include "utilities/globalDefinitions.hpp" | |
30 | |
31 // Bytes needed to pad type to avoid cache-line sharing; alignment should be the | |
32 // expected cache line size (a power of two). The first addend avoids sharing | |
33 // when the start address is not a multiple of alignment; the second maintains | |
34 // alignment of starting addresses that happen to be a multiple. | |
35 #define PADDING_SIZE(type, alignment) \ | |
36 ((alignment) + align_size_up_(sizeof(type), alignment)) | |
37 | |
38 // Templates to create a subclass padded to avoid cache line sharing. These are | |
39 // effective only when applied to derived-most (leaf) classes. | |
40 | |
41 // When no args are passed to the base ctor. | |
42 template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> | |
43 class Padded : public T { | |
44 private: | |
45 char _pad_buf_[PADDING_SIZE(T, alignment)]; | |
46 }; | |
47 | |
48 // When either 0 or 1 args may be passed to the base ctor. | |
49 template <class T, typename Arg1T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> | |
50 class Padded01 : public T { | |
51 public: | |
52 Padded01(): T() { } | |
53 Padded01(Arg1T arg1): T(arg1) { } | |
54 private: | |
55 char _pad_buf_[PADDING_SIZE(T, alignment)]; | |
56 }; | |
57 | |
58 // Super class of PaddedEnd when pad_size != 0. | |
59 template <class T, size_t pad_size> | |
60 class PaddedEndImpl : public T { | |
61 private: | |
62 char _pad_buf[pad_size]; | |
63 }; | |
64 | |
65 // Super class of PaddedEnd when pad_size == 0. | |
66 template <class T> | |
67 class PaddedEndImpl<T, /*pad_size*/ 0> : public T { | |
68 // No padding. | |
69 }; | |
70 | |
71 #define PADDED_END_SIZE(type, alignment) (align_size_up_(sizeof(type), alignment) - sizeof(type)) | |
72 | |
73 // More memory conservative implementation of Padded. The subclass adds the | |
74 // minimal amount of padding needed to make the size of the objects be aligned. | |
75 // This will help reducing false sharing, | |
76 // if the start address is a multiple of alignment. | |
77 template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> | |
78 class PaddedEnd : public PaddedEndImpl<T, PADDED_END_SIZE(T, alignment)> { | |
79 // C++ don't allow zero-length arrays. The padding is put in a | |
80 // super class that is specialized for the pad_size == 0 case. | |
81 }; | |
82 | |
83 // Helper class to create an array of PaddedEnd<T> objects. All elements will | |
84 // start at a multiple of alignment and the size will be aligned to alignment. | |
85 template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE> | |
86 class PaddedArray { | |
87 public: | |
88 // Creates an aligned padded array. | |
89 // The memory can't be deleted since the raw memory chunk is not returned. | |
90 static PaddedEnd<T>* create_unfreeable(uint length); | |
91 }; | |
92 | |
93 #endif // SHARE_VM_MEMORY_PADDED_HPP |