view src/share/vm/utilities/nativeCallStack.cpp @ 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 c6211b707068
children
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/*
 * Copyright (c) 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 "precompiled.hpp"
#include "runtime/os.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/nativeCallStack.hpp"

const NativeCallStack NativeCallStack::EMPTY_STACK(0, false);

NativeCallStack::NativeCallStack(int toSkip, bool fillStack) :
  _hash_value(0) {

#if !PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
  fillStack = false;
#endif

  if (fillStack) {
    os::get_native_stack(_stack, NMT_TrackingStackDepth, toSkip);
  } else {
    for (int index = 0; index < NMT_TrackingStackDepth; index ++) {
      _stack[index] = NULL;
    }
  }
}

NativeCallStack::NativeCallStack(address* pc, int frameCount) {
  int frameToCopy = (frameCount < NMT_TrackingStackDepth) ?
    frameCount : NMT_TrackingStackDepth;
  int index;
  for (index = 0; index < frameToCopy; index ++) {
    _stack[index] = pc[index];
  }
  for (; index < NMT_TrackingStackDepth; index ++) {
    _stack[index] = NULL;
  }
}

// number of stack frames captured
int NativeCallStack::frames() const {
  int index;
  for (index = 0; index < NMT_TrackingStackDepth; index ++) {
    if (_stack[index] == NULL) {
      break;
    }
  }
  return index;
}

// Hash code. Any better algorithm?
int NativeCallStack::hash() const {
  long hash_val = _hash_value;
  if (hash_val == 0) {
    long pc;
    int  index;
    for (index = 0; index < NMT_TrackingStackDepth; index ++) {
      pc = (long)_stack[index];
      if (pc == 0) break;
      hash_val += pc;
    }

    NativeCallStack* p = const_cast<NativeCallStack*>(this);
    p->_hash_value = (int)(hash_val & 0xFFFFFFFF);
  }
  return _hash_value;
}

void NativeCallStack::print_on(outputStream* out) const {
  print_on(out, 0);
}

// Decode and print this call path
void NativeCallStack::print_on(outputStream* out, int indent) const {
  address pc;
  char    buf[1024];
  int     offset;
  if (is_empty()) {
    for (int index = 0; index < indent; index ++) out->print(" ");
#if PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
    out->print("[BOOTSTRAP]");
#else
    out->print("[No stack]");
#endif
  } else {
    for (int frame = 0; frame < NMT_TrackingStackDepth; frame ++) {
      pc = get_frame(frame);
      if (pc == NULL) break;
      // Print indent
      for (int index = 0; index < indent; index ++) out->print(" ");
      if (os::dll_address_to_function_name(pc, buf, sizeof(buf), &offset)) {
        out->print_cr("[" PTR_FORMAT "] %s+0x%x", p2i(pc), buf, offset);
      } else {
        out->print_cr("[" PTR_FORMAT "]", p2i(pc));
      }
    }
  }
}