jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/heapRegionBounds.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 /*

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

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

    13  * accompanied this code).

    14  *

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    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP

    28 class HeapRegionBounds : public AllStatic {

    29 private:

    30   // Minimum region size; we won't go lower than that.

    31   // We might want to decrease this in the future, to deal with small

    32   // heaps a bit more efficiently.

    33   static const size_t MIN_REGION_SIZE = 1024 * 1024;

    35   // Maximum region size; we don't go higher than that. There's a good

    36   // reason for having an upper bound. We don't want regions to get too

    37   // large, otherwise cleanup's effectiveness would decrease as there

    38   // will be fewer opportunities to find totally empty regions after

    39   // marking.

    40   static const size_t MAX_REGION_SIZE = 32 * 1024 * 1024;

    42   // The automatic region size calculation will try to have around this

    43   // many regions in the heap (based on the min heap size).

    44   static const size_t TARGET_REGION_NUMBER = 2048;

    46 public:

    47   static inline size_t min_size();

    48   static inline size_t max_size();

    49   static inline size_t target_number();

    50 };

    52 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP

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

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

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