Mercurial > hg > truffle
annotate src/share/vm/memory/modRefBarrierSet.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 | 3205e78d8193 |
| children | 8a9bb7821e28 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 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 | |
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| 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 | |
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| 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #ifndef SHARE_VM_MEMORY_MODREFBARRIERSET_HPP |
| 26 #define SHARE_VM_MEMORY_MODREFBARRIERSET_HPP | |
| 27 | |
| 28 #include "memory/barrierSet.hpp" | |
| 29 | |
| 0 | 30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and |
| 31 // enumerate ref fields that have been modified (since the last | |
| 32 // enumeration), using a card table. | |
| 33 | |
| 34 class OopClosure; | |
| 35 class Generation; | |
| 36 | |
| 37 class ModRefBarrierSet: public BarrierSet { | |
| 38 public: | |
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39 |
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40 ModRefBarrierSet() { _kind = BarrierSet::ModRef; } |
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41 |
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42 bool is_a(BarrierSet::Name bsn) { |
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43 return bsn == BarrierSet::ModRef; |
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44 } |
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45 |
| 0 | 46 // Barriers only on ref writes. |
| 47 bool has_read_ref_barrier() { return false; } | |
| 48 bool has_read_prim_barrier() { return false; } | |
| 49 bool has_write_ref_barrier() { return true; } | |
| 50 bool has_write_prim_barrier() { return false; } | |
| 51 | |
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52 bool read_ref_needs_barrier(void* field) { return false; } |
| 0 | 53 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; } |
| 54 bool write_prim_needs_barrier(HeapWord* field, size_t bytes, | |
| 55 juint val1, juint val2) { return false; } | |
| 56 | |
| 57 void write_prim_field(oop obj, size_t offset, size_t bytes, | |
| 58 juint val1, juint val2) {} | |
| 59 | |
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60 void read_ref_field(void* field) {} |
| 0 | 61 void read_prim_field(HeapWord* field, size_t bytes) {} |
| 62 protected: | |
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63 virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0; |
| 0 | 64 public: |
| 65 void write_prim_field(HeapWord* field, size_t bytes, | |
| 66 juint val1, juint val2) {} | |
| 67 | |
| 68 bool has_read_ref_array_opt() { return false; } | |
| 69 bool has_read_prim_array_opt() { return false; } | |
| 70 bool has_write_prim_array_opt() { return false; } | |
| 71 | |
| 72 bool has_read_region_opt() { return false; } | |
| 73 | |
| 74 | |
| 75 // These operations should assert false unless the correponding operation | |
| 76 // above returns true. | |
| 77 void read_ref_array(MemRegion mr) { | |
| 78 assert(false, "can't call"); | |
| 79 } | |
| 80 void read_prim_array(MemRegion mr) { | |
| 81 assert(false, "can't call"); | |
| 82 } | |
| 83 void write_prim_array(MemRegion mr) { | |
| 84 assert(false, "can't call"); | |
| 85 } | |
| 86 void read_region(MemRegion mr) { | |
| 87 assert(false, "can't call"); | |
| 88 } | |
| 89 | |
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90 // Causes all refs in "mr" to be assumed to be modified. If "whole_heap" |
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91 // is true, the caller asserts that the entire heap is being invalidated, |
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92 // which may admit an optimized implementation for some barriers. |
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93 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0; |
| 0 | 94 |
| 95 // The caller guarantees that "mr" contains no references. (Perhaps it's | |
| 96 // objects have been moved elsewhere.) | |
| 97 virtual void clear(MemRegion mr) = 0; | |
| 98 | |
| 99 // Pass along the argument to the superclass. | |
| 100 ModRefBarrierSet(int max_covered_regions) : | |
| 101 BarrierSet(max_covered_regions) {} | |
| 102 }; | |
| 1972 | 103 |
| 104 #endif // SHARE_VM_MEMORY_MODREFBARRIERSET_HPP |