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src/share/vm/gc_implementation/g1/vm_operations_g1.hpp@631f79e71e90
src/share/vm/gc_implementation/g1/vm_operations_g1.hpp
Tue, 24 Aug 2010 17:24:33 -0400
- author
- tonyp
- date
- Tue, 24 Aug 2010 17:24:33 -0400
- changeset 2315
- 631f79e71e90
- parent 2314
- f95d63e2154a
- child 2532
- c798c277ddd1
- permissions
- -rw-r--r--
6974966: G1: unnecessary direct-to-old allocations
Summary: This change revamps the slow allocation path of G1. Improvements include the following: a) Allocations directly to old regions are now totally banned. G1 now only allows allocations out of young regions (with the only exception being humongous regions). b) The thread that allocates a new region (which is now guaranteed to be young) does not dirty all its cards. Each thread that successfully allocates out of a young region is now responsible for dirtying the cards that corresponding to the "block" that just got allocated. c) allocate_new_tlab() and mem_allocate() are now implemented differently and TLAB allocations are only done by allocate_new_tlab(). d) If a thread schedules an evacuation pause in order to satisfy an allocation request, it will perform the allocation at the end of the safepoint so that the thread that initiated the GC also gets "first pick" of any space made available by the GC. e) If a thread is unable to allocate a humongous object it will schedule an evacuation pause in case it reclaims enough regions so that the humongous allocation can be satisfied aftewards. f) The G1 policy is more careful to set the young list target length to be the survivor number +1. g) Lots of code tidy up, removal, refactoring to make future changes easier.
Reviewed-by: johnc, ysr
1 /*
2 * Copyright (c) 2001, 2010, 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.
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_VM_OPERATIONS_G1_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_VM_OPERATIONS_G1_HPP
28 #include "gc_implementation/shared/vmGCOperations.hpp"
30 // VM_operations for the G1 collector.
31 // VM_GC_Operation:
32 // - VM_CGC_Operation
33 // - VM_G1CollectFull
34 // - VM_G1OperationWithAllocRequest
35 // - VM_G1CollectForAllocation
36 // - VM_G1IncCollectionPause
38 class VM_G1OperationWithAllocRequest: public VM_GC_Operation {
39 protected:
40 size_t _word_size;
41 HeapWord* _result;
42 bool _pause_succeeded;
44 public:
45 VM_G1OperationWithAllocRequest(unsigned int gc_count_before,
46 size_t word_size)
47 : VM_GC_Operation(gc_count_before),
48 _word_size(word_size), _result(NULL), _pause_succeeded(false) { }
49 HeapWord* result() { return _result; }
50 bool pause_succeeded() { return _pause_succeeded; }
51 };
53 class VM_G1CollectFull: public VM_GC_Operation {
54 public:
55 VM_G1CollectFull(unsigned int gc_count_before,
56 unsigned int full_gc_count_before,
57 GCCause::Cause cause)
58 : VM_GC_Operation(gc_count_before, full_gc_count_before) {
59 _gc_cause = cause;
60 }
61 virtual VMOp_Type type() const { return VMOp_G1CollectFull; }
62 virtual void doit();
63 virtual const char* name() const {
64 return "full garbage-first collection";
65 }
66 };
68 class VM_G1CollectForAllocation: public VM_G1OperationWithAllocRequest {
69 public:
70 VM_G1CollectForAllocation(unsigned int gc_count_before,
71 size_t word_size);
72 virtual VMOp_Type type() const { return VMOp_G1CollectForAllocation; }
73 virtual void doit();
74 virtual const char* name() const {
75 return "garbage-first collection to satisfy allocation";
76 }
77 };
79 class VM_G1IncCollectionPause: public VM_G1OperationWithAllocRequest {
80 private:
81 bool _should_initiate_conc_mark;
82 double _target_pause_time_ms;
83 unsigned int _full_collections_completed_before;
84 public:
85 VM_G1IncCollectionPause(unsigned int gc_count_before,
86 size_t word_size,
87 bool should_initiate_conc_mark,
88 double target_pause_time_ms,
89 GCCause::Cause gc_cause);
90 virtual VMOp_Type type() const { return VMOp_G1IncCollectionPause; }
91 virtual void doit();
92 virtual void doit_epilogue();
93 virtual const char* name() const {
94 return "garbage-first incremental collection pause";
95 }
96 };
98 // Concurrent GC stop-the-world operations such as initial and final mark;
99 // consider sharing these with CMS's counterparts.
100 class VM_CGC_Operation: public VM_Operation {
101 VoidClosure* _cl;
102 const char* _printGCMessage;
103 public:
104 VM_CGC_Operation(VoidClosure* cl, const char *printGCMsg)
105 : _cl(cl), _printGCMessage(printGCMsg) { }
106 virtual VMOp_Type type() const { return VMOp_CGC_Operation; }
107 virtual void doit();
108 virtual bool doit_prologue();
109 virtual void doit_epilogue();
110 virtual const char* name() const {
111 return "concurrent gc";
112 }
113 };
115 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_VM_OPERATIONS_G1_HPP
