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src/share/vm/gc_implementation/g1/heapRegionBounds.hpp@e7d0505c8a30 (annotated)
src/share/vm/gc_implementation/g1/heapRegionBounds.hpp
Fri, 10 Oct 2014 15:51:58 +0200
- author
- tschatzl
- date
- Fri, 10 Oct 2014 15:51:58 +0200
- changeset 7257
- e7d0505c8a30
- parent 7137
- 5248357b7113
- 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
| sjohanss@7137 | 1 | /* |
| sjohanss@7137 | 2 | * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. |
| sjohanss@7137 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| sjohanss@7137 | 4 | * |
| sjohanss@7137 | 5 | * This code is free software; you can redistribute it and/or modify it |
| sjohanss@7137 | 6 | * under the terms of the GNU General Public License version 2 only, as |
| sjohanss@7137 | 7 | * published by the Free Software Foundation. |
| sjohanss@7137 | 8 | * |
| sjohanss@7137 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| sjohanss@7137 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| sjohanss@7137 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| sjohanss@7137 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
| sjohanss@7137 | 13 | * accompanied this code). |
| sjohanss@7137 | 14 | * |
| sjohanss@7137 | 15 | * You should have received a copy of the GNU General Public License version |
| sjohanss@7137 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
| sjohanss@7137 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| sjohanss@7137 | 18 | * |
| sjohanss@7137 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| sjohanss@7137 | 20 | * or visit www.oracle.com if you need additional information or have any |
| sjohanss@7137 | 21 | * questions. |
| sjohanss@7137 | 22 | * |
| sjohanss@7137 | 23 | */ |
| sjohanss@7137 | 24 | |
| sjohanss@7137 | 25 | #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP |
| sjohanss@7137 | 26 | #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP |
| sjohanss@7137 | 27 | |
| sjohanss@7137 | 28 | class HeapRegionBounds : public AllStatic { |
| sjohanss@7137 | 29 | private: |
| sjohanss@7137 | 30 | // Minimum region size; we won't go lower than that. |
| sjohanss@7137 | 31 | // We might want to decrease this in the future, to deal with small |
| sjohanss@7137 | 32 | // heaps a bit more efficiently. |
| sjohanss@7137 | 33 | static const size_t MIN_REGION_SIZE = 1024 * 1024; |
| sjohanss@7137 | 34 | |
| sjohanss@7137 | 35 | // Maximum region size; we don't go higher than that. There's a good |
| sjohanss@7137 | 36 | // reason for having an upper bound. We don't want regions to get too |
| sjohanss@7137 | 37 | // large, otherwise cleanup's effectiveness would decrease as there |
| sjohanss@7137 | 38 | // will be fewer opportunities to find totally empty regions after |
| sjohanss@7137 | 39 | // marking. |
| sjohanss@7137 | 40 | static const size_t MAX_REGION_SIZE = 32 * 1024 * 1024; |
| sjohanss@7137 | 41 | |
| sjohanss@7137 | 42 | // The automatic region size calculation will try to have around this |
| sjohanss@7137 | 43 | // many regions in the heap (based on the min heap size). |
| sjohanss@7137 | 44 | static const size_t TARGET_REGION_NUMBER = 2048; |
| sjohanss@7137 | 45 | |
| sjohanss@7137 | 46 | public: |
| sjohanss@7137 | 47 | static inline size_t min_size(); |
| sjohanss@7137 | 48 | static inline size_t max_size(); |
| sjohanss@7137 | 49 | static inline size_t target_number(); |
| sjohanss@7137 | 50 | }; |
| sjohanss@7137 | 51 | |
| sjohanss@7137 | 52 | #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONBOUNDS_HPP |
