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