1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/memory/padded.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,112 @@
1.4 +/*
1.5 + * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_MEMORY_PADDED_HPP
1.29 +#define SHARE_VM_MEMORY_PADDED_HPP
1.30 +
1.31 +#include "memory/allocation.hpp"
1.32 +#include "utilities/globalDefinitions.hpp"
1.33 +
1.34 +// Bytes needed to pad type to avoid cache-line sharing; alignment should be the
1.35 +// expected cache line size (a power of two). The first addend avoids sharing
1.36 +// when the start address is not a multiple of alignment; the second maintains
1.37 +// alignment of starting addresses that happen to be a multiple.
1.38 +#define PADDING_SIZE(type, alignment) \
1.39 + ((alignment) + align_size_up_(sizeof(type), alignment))
1.40 +
1.41 +// Templates to create a subclass padded to avoid cache line sharing. These are
1.42 +// effective only when applied to derived-most (leaf) classes.
1.43 +
1.44 +// When no args are passed to the base ctor.
1.45 +template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.46 +class Padded : public T {
1.47 + private:
1.48 + char _pad_buf_[PADDING_SIZE(T, alignment)];
1.49 +};
1.50 +
1.51 +// When either 0 or 1 args may be passed to the base ctor.
1.52 +template <class T, typename Arg1T, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.53 +class Padded01 : public T {
1.54 + public:
1.55 + Padded01(): T() { }
1.56 + Padded01(Arg1T arg1): T(arg1) { }
1.57 + private:
1.58 + char _pad_buf_[PADDING_SIZE(T, alignment)];
1.59 +};
1.60 +
1.61 +// Super class of PaddedEnd when pad_size != 0.
1.62 +template <class T, size_t pad_size>
1.63 +class PaddedEndImpl : public T {
1.64 + private:
1.65 + char _pad_buf[pad_size];
1.66 +};
1.67 +
1.68 +// Super class of PaddedEnd when pad_size == 0.
1.69 +template <class T>
1.70 +class PaddedEndImpl<T, /*pad_size*/ 0> : public T {
1.71 + // No padding.
1.72 +};
1.73 +
1.74 +#define PADDED_END_SIZE(type, alignment) (align_size_up_(sizeof(type), alignment) - sizeof(type))
1.75 +
1.76 +// More memory conservative implementation of Padded. The subclass adds the
1.77 +// minimal amount of padding needed to make the size of the objects be aligned.
1.78 +// This will help reducing false sharing,
1.79 +// if the start address is a multiple of alignment.
1.80 +template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.81 +class PaddedEnd : public PaddedEndImpl<T, PADDED_END_SIZE(T, alignment)> {
1.82 + // C++ don't allow zero-length arrays. The padding is put in a
1.83 + // super class that is specialized for the pad_size == 0 case.
1.84 +};
1.85 +
1.86 +// Helper class to create an array of PaddedEnd<T> objects. All elements will
1.87 +// start at a multiple of alignment and the size will be aligned to alignment.
1.88 +template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.89 +class PaddedArray {
1.90 + public:
1.91 + // Creates an aligned padded array.
1.92 + // The memory can't be deleted since the raw memory chunk is not returned.
1.93 + static PaddedEnd<T>* create_unfreeable(uint length);
1.94 +};
1.95 +
1.96 +// Helper class to create an array of references to arrays of primitive types
1.97 +// Both the array of references and the data arrays are aligned to the given
1.98 +// alignment. The allocated memory is zero-filled.
1.99 +template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.100 +class Padded2DArray {
1.101 + public:
1.102 + // Creates an aligned padded 2D array.
1.103 + // The memory cannot be deleted since the raw memory chunk is not returned.
1.104 + static T** create_unfreeable(uint rows, uint columns, size_t* allocation_size = NULL);
1.105 +};
1.106 +
1.107 +// Helper class to create an array of T objects. The array as a whole will
1.108 +// start at a multiple of alignment and its size will be aligned to alignment.
1.109 +template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE>
1.110 +class PaddedPrimitiveArray {
1.111 + public:
1.112 + static T* create_unfreeable(size_t length);
1.113 +};
1.114 +
1.115 +#endif // SHARE_VM_MEMORY_PADDED_HPP
