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

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

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

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

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 7195: c02ec279b062
child 9861: a248d0be1309
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) 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_HEAPREGIONTYPE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP
 #include "memory/allocation.hpp"
 #define hrt_assert_is_valid(tag) \
   assert(is_valid((tag)), err_msg("invalid HR type: %u", (uint) (tag)))
 class HeapRegionType VALUE_OBJ_CLASS_SPEC {
 private:
   // We encode the value of the heap region type so the generation can be
   // determined quickly. The tag is split into two parts:
   //
   //   major type (young, humongous)                         : top N-1 bits
   //   minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
   //
   // If there's need to increase the number of minor types in the
   // future, we'll have to increase the size of the latter and hence
   // decrease the size of the former.
   //
   // 0000 0 [ 0] Free
   //
   // 0001 0      Young Mask
   // 0001 0 [ 2] Eden
   // 0001 1 [ 3] Survivor
   //
   // 0010 0      Humongous Mask
   // 0010 0 [ 4] Humongous Starts
   // 0010 1 [ 5] Humongous Continues
   //
   // 01000 [ 8] Old
   typedef enum {
     FreeTag       = 0,
     YoungMask     = 2,
     EdenTag       = YoungMask,
     SurvTag       = YoungMask + 1,
     HumMask       = 4,
     HumStartsTag  = HumMask,
     HumContTag    = HumMask + 1,
     OldTag        = 8
   } Tag;
   volatile Tag _tag;
   static bool is_valid(Tag tag);
   Tag get() const {
     hrt_assert_is_valid(_tag);
     return _tag;
   }
   // Sets the type to 'tag'.
   void set(Tag tag) {
     hrt_assert_is_valid(tag);
     hrt_assert_is_valid(_tag);
     _tag = tag;
   }
   // Sets the type to 'tag', expecting the type to be 'before'. This
   // is available for when we want to add sanity checking to the type
   // transition.
   void set_from(Tag tag, Tag before) {
     hrt_assert_is_valid(tag);
     hrt_assert_is_valid(before);
     hrt_assert_is_valid(_tag);
     assert(_tag == before,
            err_msg("HR tag: %u, expected: %u new tag; %u", _tag, before, tag));
     _tag = tag;
   }
 public:
   // Queries
   bool is_free() const { return get() == FreeTag; }
   bool is_young()    const { return (get() & YoungMask) != 0; }
   bool is_eden()     const { return get() == EdenTag;  }
   bool is_survivor() const { return get() == SurvTag;  }
   bool is_humongous()           const { return (get() & HumMask) != 0; }
   bool is_starts_humongous()    const { return get() == HumStartsTag;  }
   bool is_continues_humongous() const { return get() == HumContTag;    }
   bool is_old() const { return get() == OldTag; }
   // Setters
   void set_free() { set(FreeTag); }
   void set_eden()        { set_from(EdenTag, FreeTag); }
   void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
   void set_survivor()    { set_from(SurvTag, FreeTag); }
   void set_starts_humongous()    { set_from(HumStartsTag, FreeTag); }
   void set_continues_humongous() { set_from(HumContTag,   FreeTag); }
   void set_old() { set(OldTag); }
   // Misc
   const char* get_str() const;
   const char* get_short_str() const;
   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

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

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