jdk8-mips64-public/hotspot: src/share/vm/memory/padded.hpp@461159cd7a91 (annotated)

src/share/vm/memory/padded.hpp@461159cd7a91 (annotated)

src/share/vm/memory/padded.hpp

Thu, 26 Sep 2013 12:18:21 +0200

author: tschatzl
date: Thu, 26 Sep 2013 12:18:21 +0200
changeset 5775: 461159cd7a91
parent 5515: 9766f73e770d
child 6403: d7070f371770
permissions: -rw-r--r--

Merge

 /*
  * Copyright (c) 2013, 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/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_size_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_size_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++ don't allow zero-length arrays. The padding is put in a
   // super class that is specialized for the pad_size == 0 case.
 };
 // 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);
 };
 #endif // SHARE_VM_MEMORY_PADDED_HPP

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src/share/vm/memory/padded.hpp@461159cd7a91 (annotated)

src/share/vm/memory/padded.hpp