view src/share/vm/memory/padded.inline.hpp @ 20543:e7d0505c8a30

8059758: Footprint regressions with JDK-8038423 Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything. Reviewed-by: jwilhelm, brutisso
author tschatzl
date Fri, 10 Oct 2014 15:51:58 +0200
parents 5479cb006184
children
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/*
 * 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.
 *
 */

#include "memory/allocation.inline.hpp"
#include "memory/padded.hpp"
#include "utilities/debug.hpp"
#include "utilities/globalDefinitions.hpp"

// Creates an aligned padded array.
// The memory can't be deleted since the raw memory chunk is not returned.
template <class T, MEMFLAGS flags, size_t alignment>
PaddedEnd<T>* PaddedArray<T, flags, alignment>::create_unfreeable(uint length) {
  // Check that the PaddedEnd class works as intended.
  STATIC_ASSERT(is_size_aligned_(sizeof(PaddedEnd<T>), alignment));

  // Allocate a chunk of memory large enough to allow for some alignment.
  void* chunk = AllocateHeap(length * sizeof(PaddedEnd<T, alignment>) + alignment, flags);

  // Make the initial alignment.
  PaddedEnd<T>* aligned_padded_array = (PaddedEnd<T>*)align_pointer_up(chunk, alignment);

  // Call the default constructor for each element.
  for (uint i = 0; i < length; i++) {
    ::new (&aligned_padded_array[i]) T();
  }

  return aligned_padded_array;
}

template <class T, MEMFLAGS flags, size_t alignment>
T** Padded2DArray<T, flags, alignment>::create_unfreeable(uint rows, uint columns, size_t* allocation_size) {
  // Calculate and align the size of the first dimension's table.
  size_t table_size = align_size_up_(rows * sizeof(T*), alignment);
  // The size of the separate rows.
  size_t row_size = align_size_up_(columns * sizeof(T), alignment);
  // Total size consists of the indirection table plus the rows.
  size_t total_size = table_size + rows * row_size + alignment;

  // Allocate a chunk of memory large enough to allow alignment of the chunk.
  void* chunk = AllocateHeap(total_size, flags);
  // Clear the allocated memory.
  memset(chunk, 0, total_size);
  // Align the chunk of memory.
  T** result = (T**)align_pointer_up(chunk, alignment);
  void* data_start = (void*)((uintptr_t)result + table_size);

  // Fill in the row table.
  for (size_t i = 0; i < rows; i++) {
    result[i] = (T*)((uintptr_t)data_start + i * row_size);
  }

  if (allocation_size != NULL) {
    *allocation_size = total_size;
  }

  return result;
}

template <class T, MEMFLAGS flags, size_t alignment>
T* PaddedPrimitiveArray<T, flags, alignment>::create_unfreeable(size_t length) {
  // Allocate a chunk of memory large enough to allow for some alignment.
  void* chunk = AllocateHeap(length * sizeof(T) + alignment, flags);

  memset(chunk, 0, length * sizeof(T) + alignment);

  return (T*)align_pointer_up(chunk, alignment);
}