jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1AllocationContext.hpp@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

     1 /*

     2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATIONCONTEXT_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATIONCONTEXT_HPP

    28 #include "memory/allocation.hpp"

    30 typedef unsigned char AllocationContext_t;

    32 class AllocationContext : AllStatic {

    33 public:

    34   // Currently used context

    35   static AllocationContext_t current() {

    36     return 0;

    37   }

    38   // System wide default context

    39   static AllocationContext_t system() {

    40     return 0;

    41   }

    42 };

    44 class AllocationContextStats: public StackObj {

    45 public:

    46   inline void clear() { }

    47   inline void update(bool full_gc) { }

    48   inline void update_at_remark() { }

    49   inline bool available() { return false; }

    50 };

    52 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATIONCONTEXT_HPP

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/gc_implementation/g1/g1AllocationContext.hpp@e7d0505c8a30

src/share/vm/gc_implementation/g1/g1AllocationContext.hpp