| /* |
| * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_MEMORY_PADDED_HPP |
| #define SHARE_VM_MEMORY_PADDED_HPP |
| |
| #include "memory/allocation.hpp" |
| #include "utilities/align.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| |
| // Bytes needed to pad type to avoid cache-line sharing; alignment should be the |
| // expected cache line size (a power of two). The first addend avoids sharing |
| // when the start address is not a multiple of alignment; the second maintains |
| // alignment of starting addresses that happen to be a multiple. |
| #define PADDING_SIZE(type, alignment) \ |
| ((alignment) + align_up_(sizeof(type), (alignment))) |
| |
| // Templates to create a subclass padded to avoid cache line sharing. These are |
| // effective only when applied to derived-most (leaf) classes. |
| |
| // When no args are passed to the base ctor. |
| template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class Padded : public T { |
| private: |
| char _pad_buf_[PADDING_SIZE(T, alignment)]; |
| }; |
| |
| // When either 0 or 1 args may be passed to the base ctor. |
| template <class T, typename Arg1T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class Padded01 : public T { |
| public: |
| Padded01(): T() { } |
| Padded01(Arg1T arg1): T(arg1) { } |
| private: |
| char _pad_buf_[PADDING_SIZE(T, alignment)]; |
| }; |
| |
| // Super class of PaddedEnd when pad_size != 0. |
| template <class T, size_t pad_size> |
| class PaddedEndImpl : public T { |
| private: |
| char _pad_buf[pad_size]; |
| }; |
| |
| // Super class of PaddedEnd when pad_size == 0. |
| template <class T> |
| class PaddedEndImpl<T, /*pad_size*/ 0> : public T { |
| // No padding. |
| }; |
| |
| #define PADDED_END_SIZE(type, alignment) (align_up_(sizeof(type), (alignment)) - sizeof(type)) |
| |
| // More memory conservative implementation of Padded. The subclass adds the |
| // minimal amount of padding needed to make the size of the objects be aligned. |
| // This will help reducing false sharing, |
| // if the start address is a multiple of alignment. |
| template <class T, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class PaddedEnd : public PaddedEndImpl<T, PADDED_END_SIZE(T, alignment)> { |
| // C++ doesn't allow zero-length arrays. The padding is put in a |
| // super class that is specialized for the pad_size == 0 case. |
| }; |
| |
| // Similar to PaddedEnd, this macro defines a _pad_buf#id field |
| // that is (alignment - size) bytes in size. This macro is used |
| // to add padding in between non-class fields in a class or struct. |
| #define DEFINE_PAD_MINUS_SIZE(id, alignment, size) \ |
| char _pad_buf##id[(alignment) - (size)] |
| |
| // Helper class to create an array of PaddedEnd<T> objects. All elements will |
| // start at a multiple of alignment and the size will be aligned to alignment. |
| template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class PaddedArray { |
| public: |
| // Creates an aligned padded array. |
| // The memory can't be deleted since the raw memory chunk is not returned. |
| static PaddedEnd<T>* create_unfreeable(uint length); |
| }; |
| |
| // Helper class to create an array of references to arrays of primitive types |
| // Both the array of references and the data arrays are aligned to the given |
| // alignment. The allocated memory is zero-filled. |
| template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class Padded2DArray { |
| public: |
| // Creates an aligned padded 2D array. |
| // The memory cannot be deleted since the raw memory chunk is not returned. |
| static T** create_unfreeable(uint rows, uint columns, size_t* allocation_size = NULL); |
| }; |
| |
| // Helper class to create an array of T objects. The array as a whole will |
| // start at a multiple of alignment and its size will be aligned to alignment. |
| template <class T, MEMFLAGS flags, size_t alignment = DEFAULT_CACHE_LINE_SIZE> |
| class PaddedPrimitiveArray { |
| public: |
| static T* create_unfreeable(size_t length); |
| }; |
| |
| #endif // SHARE_VM_MEMORY_PADDED_HPP |