jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1InCSetState.hpp@b7c8142a9e0b (annotated)

src/share/vm/gc_implementation/g1/g1InCSetState.hpp@b7c8142a9e0b (annotated)

src/share/vm/gc_implementation/g1/g1InCSetState.hpp

Wed, 15 Apr 2015 12:16:01 -0400

author: kbarrett
date: Wed, 15 Apr 2015 12:16:01 -0400
changeset 7830: b7c8142a9e0b
parent 7651: c132be0fb74d
child 9327: f96fcd9e1e1b
permissions: -rw-r--r--

8069367: Eagerly reclaimed humongous objects left on mark stack
Summary: Prevent eager reclaim of objects that might be on mark stack.
Reviewed-by: brutisso, tschatzl

 /*
  * 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.
  *
  */
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP
 #include "gc_implementation/g1/g1BiasedArray.hpp"
 #include "memory/allocation.hpp"
 // Per-region state during garbage collection.
 struct InCSetState {
  public:
   // We use different types to represent the state value. Particularly SPARC puts
   // values in structs from "left to right", i.e. MSB to LSB. This results in many
   // unnecessary shift operations when loading and storing values of this type.
   // This degrades performance significantly (>10%) on that platform.
   // Other tested ABIs do not seem to have this problem, and actually tend to
   // favor smaller types, so we use the smallest usable type there.
 #ifdef SPARC
   #define CSETSTATE_FORMAT INTPTR_FORMAT
   typedef intptr_t in_cset_state_t;
 #else
   #define CSETSTATE_FORMAT "%d"
   typedef int8_t in_cset_state_t;
 #endif
  private:
   in_cset_state_t _value;
  public:
   enum {
     // Selection of the values were driven to micro-optimize the encoding and
     // frequency of the checks.
     // The most common check is whether the region is in the collection set or not.
     // This encoding allows us to use an != 0 check which in some architectures
     // (x86*) can be encoded slightly more efficently than a normal comparison
     // against zero.
     // The same situation occurs when checking whether the region is humongous
     // or not, which is encoded by values < 0.
     // The other values are simply encoded in increasing generation order, which
     // makes getting the next generation fast by a simple increment.
     Humongous    = -1,    // The region is humongous - note that actually any value < 0 would be possible here.
     NotInCSet    =  0,    // The region is not in the collection set.
     Young        =  1,    // The region is in the collection set and a young region.
     Old          =  2,    // The region is in the collection set and an old region.
     Num
   };
   InCSetState(in_cset_state_t value = NotInCSet) : _value(value) {
     assert(is_valid(), err_msg("Invalid state %d", _value));
   }
   in_cset_state_t value() const        { return _value; }
   void set_old()                       { _value = Old; }
   bool is_in_cset_or_humongous() const { return _value != NotInCSet; }
   bool is_in_cset() const              { return _value > NotInCSet; }
   bool is_humongous() const            { return _value < NotInCSet; }
   bool is_young() const                { return _value == Young; }
   bool is_old() const                  { return _value == Old; }
 #ifdef ASSERT
   bool is_default() const              { return !is_in_cset_or_humongous(); }
   bool is_valid() const                { return (_value >= Humongous) && (_value < Num); }
   bool is_valid_gen() const            { return (_value >= Young && _value <= Old); }
 #endif
 };
 // Instances of this class are used for quick tests on whether a reference points
 // into the collection set and into which generation or is a humongous object
 //
 // Each of the array's elements indicates whether the corresponding region is in
 // the collection set and if so in which generation, or a humongous region.
 //
 // We use this to speed up reference processing during young collection and
 // quickly reclaim humongous objects. For the latter, by making a humongous region
 // succeed this test, we sort-of add it to the collection set. During the reference
 // iteration closures, when we see a humongous region, we then simply mark it as
 // referenced, i.e. live.
 class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<InCSetState> {
  protected:
   InCSetState default_value() const { return InCSetState::NotInCSet; }
  public:
   void set_humongous(uintptr_t index) {
     assert(get_by_index(index).is_default(),
            err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
     set_by_index(index, InCSetState::Humongous);
   }
   void clear_humongous(uintptr_t index) {
     set_by_index(index, InCSetState::NotInCSet);
   }
   void set_in_young(uintptr_t index) {
     assert(get_by_index(index).is_default(),
            err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
     set_by_index(index, InCSetState::Young);
   }
   void set_in_old(uintptr_t index) {
     assert(get_by_index(index).is_default(),
            err_msg("State at index " INTPTR_FORMAT" should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()));
     set_by_index(index, InCSetState::Old);
   }
   bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); }
   bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); }
   InCSetState at(HeapWord* addr) const { return get_by_address(addr); }
   void clear() { G1BiasedMappedArray<InCSetState>::clear(); }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1INCSETSTATE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1InCSetState.hpp@b7c8142a9e0b (annotated)

src/share/vm/gc_implementation/g1/g1InCSetState.hpp