view src/share/vm/memory/barrierSet.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 3205e78d8193
children 4ca6dc0799b6
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/*
 * Copyright (c) 2001, 2010, 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
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 */

#ifndef SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP
#define SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP

#include "memory/barrierSet.hpp"
#include "memory/cardTableModRefBS.hpp"

// Inline functions of BarrierSet, which de-virtualize certain
// performance-critical calls when the barrier is the most common
// card-table kind.

template <class T> void BarrierSet::write_ref_field_pre(T* field, oop new_val) {
  if (kind() == CardTableModRef) {
    ((CardTableModRefBS*)this)->inline_write_ref_field_pre(field, new_val);
  } else {
    write_ref_field_pre_work(field, new_val);
  }
}

void BarrierSet::write_ref_field(void* field, oop new_val, bool release) {
  if (kind() == CardTableModRef) {
    ((CardTableModRefBS*)this)->inline_write_ref_field(field, new_val, release);
  } else {
    write_ref_field_work(field, new_val, release);
  }
}

// count is number of array elements being written
void BarrierSet::write_ref_array(HeapWord* start, size_t count) {
  assert(count <= (size_t)max_intx, "count too large");
  HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));
  // In the case of compressed oops, start and end may potentially be misaligned;
  // so we need to conservatively align the first downward (this is not
  // strictly necessary for current uses, but a case of good hygiene and,
  // if you will, aesthetics) and the second upward (this is essential for
  // current uses) to a HeapWord boundary, so we mark all cards overlapping
  // this write. If this evolves in the future to calling a
  // logging barrier of narrow oop granularity, like the pre-barrier for G1
  // (mentioned here merely by way of example), we will need to change this
  // interface, so it is "exactly precise" (if i may be allowed the adverbial
  // redundancy for emphasis) and does not include narrow oop slots not
  // included in the original write interval.
  HeapWord* aligned_start = (HeapWord*)align_size_down((uintptr_t)start, HeapWordSize);
  HeapWord* aligned_end   = (HeapWord*)align_size_up  ((uintptr_t)end,   HeapWordSize);
  // If compressed oops were not being used, these should already be aligned
  assert(UseCompressedOops || (aligned_start == start && aligned_end == end),
         "Expected heap word alignment of start and end");
#if 0
  warning("Post:\t" INTPTR_FORMAT "[" SIZE_FORMAT "] : [" INTPTR_FORMAT","INTPTR_FORMAT")\t",
                   start,            count,              aligned_start,   aligned_end);
#endif
  write_ref_array_work(MemRegion(aligned_start, aligned_end));
}


void BarrierSet::write_region(MemRegion mr) {
  if (kind() == CardTableModRef) {
    ((CardTableModRefBS*)this)->inline_write_region(mr);
  } else {
    write_region_work(mr);
  }
}

#endif // SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP