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annotate src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.hpp @ 20543: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
| author | tschatzl |
|---|---|
| date | Fri, 10 Oct 2014 15:51:58 +0200 |
| parents | 7b2fc3129653 |
| children |
| rev | line source |
|---|---|
| 20337 | 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 */ | |
| 24 | |
| 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP | |
| 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP | |
| 27 | |
| 28 #include "gc_implementation/g1/g1PageBasedVirtualSpace.hpp" | |
|
20339
7b2fc3129653
8055635: Missing include in g1RegionToSpaceMapper.hpp results in unresolved symbol of fastdebug build without precompiled headers
tschatzl
parents:
20337
diff
changeset
|
29 #include "memory/allocation.hpp" |
| 20337 | 30 #include "utilities/debug.hpp" |
| 31 | |
| 32 class G1MappingChangedListener VALUE_OBJ_CLASS_SPEC { | |
| 33 public: | |
| 34 // Fired after commit of the memory, i.e. the memory this listener is registered | |
| 35 // for can be accessed. | |
| 20543 | 36 // Zero_filled indicates that the memory can be considered as filled with zero bytes |
| 37 // when called. | |
| 38 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled) = 0; | |
| 20337 | 39 }; |
| 40 | |
| 41 // Maps region based commit/uncommit requests to the underlying page sized virtual | |
| 42 // space. | |
| 43 class G1RegionToSpaceMapper : public CHeapObj<mtGC> { | |
| 44 private: | |
| 45 G1MappingChangedListener* _listener; | |
| 46 protected: | |
| 47 // Backing storage. | |
| 48 G1PageBasedVirtualSpace _storage; | |
| 49 size_t _commit_granularity; | |
| 50 size_t _region_granularity; | |
| 51 // Mapping management | |
| 52 BitMap _commit_map; | |
| 53 | |
| 54 G1RegionToSpaceMapper(ReservedSpace rs, size_t commit_granularity, size_t region_granularity, MemoryType type); | |
| 55 | |
| 20543 | 56 void fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled); |
| 20337 | 57 public: |
| 58 MemRegion reserved() { return _storage.reserved(); } | |
| 59 | |
| 60 void set_mapping_changed_listener(G1MappingChangedListener* listener) { _listener = listener; } | |
| 61 | |
| 62 virtual ~G1RegionToSpaceMapper() { | |
| 63 _commit_map.resize(0, /* in_resource_area */ false); | |
| 64 } | |
| 65 | |
| 66 bool is_committed(uintptr_t idx) const { | |
| 67 return _commit_map.at(idx); | |
| 68 } | |
| 69 | |
| 70 virtual void commit_regions(uintptr_t start_idx, size_t num_regions = 1) = 0; | |
| 71 virtual void uncommit_regions(uintptr_t start_idx, size_t num_regions = 1) = 0; | |
| 72 | |
| 73 // Creates an appropriate G1RegionToSpaceMapper for the given parameters. | |
| 74 // The byte_translation_factor defines how many bytes in a region correspond to | |
| 75 // a single byte in the data structure this mapper is for. | |
| 76 // Eg. in the card table, this value corresponds to the size a single card | |
| 77 // table entry corresponds to. | |
| 78 static G1RegionToSpaceMapper* create_mapper(ReservedSpace rs, | |
| 79 size_t os_commit_granularity, | |
| 80 size_t region_granularity, | |
| 81 size_t byte_translation_factor, | |
| 82 MemoryType type); | |
| 83 }; | |
| 84 | |
| 85 #endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP */ |