jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 6969: 02e61cf08ab3
child 7535: 7ae4e26cb1e0
permissions: -rw-r--r--

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

 /*
  * Copyright (c) 2001, 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
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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP
 #include "memory/iterator.hpp"
 #include "oops/oopsHierarchy.hpp"
 #include "runtime/os.hpp"
 #include "utilities/debug.hpp"
 // A BufferingOops closure tries to separate out the cost of finding roots
 // from the cost of applying closures to them.  It maintains an array of
 // ref-containing locations.  Until the array is full, applying the closure
 // to an oop* merely records that location in the array.  Since this
 // closure app cost is small, an elapsed timer can approximately attribute
 // all of this cost to the cost of finding the roots.  When the array fills
 // up, the wrapped closure is applied to all elements, keeping track of
 // this elapsed time of this process, and leaving the array empty.
 // The caller must be sure to call "done" to process any unprocessed
 // buffered entriess.
 class BufferingOopClosure: public OopClosure {
   friend class TestBufferingOopClosure;
 protected:
   static const size_t BufferLength = 1024;
   // We need to know if the buffered addresses contain oops or narrowOops.
   // We can't tag the addresses the way StarTask does, because we need to
   // be able to handle unaligned addresses coming from oops embedded in code.
   //
   // The addresses for the full-sized oops are filled in from the bottom,
   // while the addresses for the narrowOops are filled in from the top.
   OopOrNarrowOopStar  _buffer[BufferLength];
   OopOrNarrowOopStar* _oop_top;
   OopOrNarrowOopStar* _narrowOop_bottom;
   OopClosure* _oc;
   double      _closure_app_seconds;
   bool is_buffer_empty() {
     return _oop_top == _buffer && _narrowOop_bottom == (_buffer + BufferLength - 1);
   }
   bool is_buffer_full() {
     return _narrowOop_bottom < _oop_top;
   }
   // Process addresses containing full-sized oops.
   void process_oops() {
     for (OopOrNarrowOopStar* curr = _buffer; curr < _oop_top; ++curr) {
       _oc->do_oop((oop*)(*curr));
     }
     _oop_top = _buffer;
   }
   // Process addresses containing narrow oops.
   void process_narrowOops() {
     for (OopOrNarrowOopStar* curr = _buffer + BufferLength - 1; curr > _narrowOop_bottom; --curr) {
       _oc->do_oop((narrowOop*)(*curr));
     }
     _narrowOop_bottom = _buffer + BufferLength - 1;
   }
   // Apply the closure to all oops and clear the buffer.
   // Accumulate the time it took.
   void process_buffer() {
     double start = os::elapsedTime();
     process_oops();
     process_narrowOops();
     _closure_app_seconds += (os::elapsedTime() - start);
   }
   void process_buffer_if_full() {
     if (is_buffer_full()) {
       process_buffer();
     }
   }
   void add_narrowOop(narrowOop* p) {
     assert(!is_buffer_full(), "Buffer should not be full");
     *_narrowOop_bottom = (OopOrNarrowOopStar)p;
     _narrowOop_bottom--;
   }
   void add_oop(oop* p) {
     assert(!is_buffer_full(), "Buffer should not be full");
     *_oop_top = (OopOrNarrowOopStar)p;
     _oop_top++;
   }
 public:
   virtual void do_oop(narrowOop* p) {
     process_buffer_if_full();
     add_narrowOop(p);
   }
   virtual void do_oop(oop* p)       {
     process_buffer_if_full();
     add_oop(p);
   }
   void done() {
     if (!is_buffer_empty()) {
       process_buffer();
     }
   }
   double closure_app_seconds() {
     return _closure_app_seconds;
   }
   BufferingOopClosure(OopClosure *oc) :
     _oc(oc),
     _oop_top(_buffer),
     _narrowOop_bottom(_buffer + BufferLength - 1),
     _closure_app_seconds(0.0) { }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp