Mon, 06 Aug 2012 12:20:14 -0700
6818524: G1: use ergonomic resizing of PLABs
Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: Brandon Mitchell <brandon@twitter.com>
1 /*
2 * Copyright (c) 2005, 2011, 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.
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_VMGCOPERATIONS_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_VMGCOPERATIONS_HPP
28 #include "memory/heapInspection.hpp"
29 #include "runtime/handles.hpp"
30 #include "runtime/jniHandles.hpp"
31 #include "runtime/synchronizer.hpp"
32 #include "runtime/vm_operations.hpp"
33 #include "prims/jvmtiExport.hpp"
35 // The following class hierarchy represents
36 // a set of operations (VM_Operation) related to GC.
37 //
38 // VM_Operation
39 // VM_GC_Operation
40 // VM_GC_HeapInspection
41 // VM_GenCollectForAllocation
42 // VM_GenCollectFull
43 // VM_GenCollectFullConcurrent
44 // VM_ParallelGCFailedAllocation
45 // VM_ParallelGCFailedPermanentAllocation
46 // VM_ParallelGCSystemGC
47 // VM_GC_Operation
48 // - implements methods common to all classes in the hierarchy:
49 // prevents multiple gc requests and manages lock on heap;
50 //
51 // VM_GC_HeapInspection
52 // - prints class histogram on SIGBREAK if PrintClassHistogram
53 // is specified; and also the attach "inspectheap" operation
54 //
55 // VM_GenCollectForAllocation
56 // VM_GenCollectForPermanentAllocation
57 // VM_ParallelGCFailedAllocation
58 // VM_ParallelGCFailedPermanentAllocation
59 // - this operation is invoked when allocation is failed;
60 // operation performs garbage collection and tries to
61 // allocate afterwards;
62 //
63 // VM_GenCollectFull
64 // VM_GenCollectFullConcurrent
65 // VM_ParallelGCSystemGC
66 // - these operations preform full collection of heaps of
67 // different kind
68 //
70 class VM_GC_Operation: public VM_Operation {
71 protected:
72 BasicLock _pending_list_basic_lock; // for refs pending list notification (PLL)
73 unsigned int _gc_count_before; // gc count before acquiring PLL
74 unsigned int _full_gc_count_before; // full gc count before acquiring PLL
75 bool _full; // whether a "full" collection
76 bool _prologue_succeeded; // whether doit_prologue succeeded
77 GCCause::Cause _gc_cause; // the putative cause for this gc op
78 bool _gc_locked; // will be set if gc was locked
80 virtual bool skip_operation() const;
82 // java.lang.ref.Reference support
83 void acquire_pending_list_lock();
84 void release_and_notify_pending_list_lock();
86 public:
87 VM_GC_Operation(unsigned int gc_count_before,
88 GCCause::Cause _cause,
89 unsigned int full_gc_count_before = 0,
90 bool full = false) {
91 _full = full;
92 _prologue_succeeded = false;
93 _gc_count_before = gc_count_before;
95 // A subclass constructor will likely overwrite the following
96 _gc_cause = _cause;
98 _gc_locked = false;
100 _full_gc_count_before = full_gc_count_before;
101 // In ParallelScavengeHeap::mem_allocate() collections can be
102 // executed within a loop and _all_soft_refs_clear can be set
103 // true after they have been cleared by a collection and another
104 // collection started so that _all_soft_refs_clear can be true
105 // when this collection is started. Don't assert that
106 // _all_soft_refs_clear have to be false here even though
107 // mutators have run. Soft refs will be cleared again in this
108 // collection.
109 }
110 ~VM_GC_Operation() {
111 CollectedHeap* ch = Universe::heap();
112 ch->collector_policy()->set_all_soft_refs_clear(false);
113 }
115 // Acquire the reference synchronization lock
116 virtual bool doit_prologue();
117 // Do notifyAll (if needed) and release held lock
118 virtual void doit_epilogue();
120 virtual bool allow_nested_vm_operations() const { return true; }
121 bool prologue_succeeded() const { return _prologue_succeeded; }
123 void set_gc_locked() { _gc_locked = true; }
124 bool gc_locked() const { return _gc_locked; }
126 static void notify_gc_begin(bool full = false);
127 static void notify_gc_end();
128 };
131 class VM_GC_HeapInspection: public VM_GC_Operation {
132 private:
133 outputStream* _out;
134 bool _full_gc;
135 bool _need_prologue;
136 public:
137 VM_GC_HeapInspection(outputStream* out, bool request_full_gc,
138 bool need_prologue) :
139 VM_GC_Operation(0 /* total collections, dummy, ignored */,
140 GCCause::_heap_inspection /* GC Cause */,
141 0 /* total full collections, dummy, ignored */,
142 request_full_gc) {
143 _out = out;
144 _full_gc = request_full_gc;
145 _need_prologue = need_prologue;
146 }
148 ~VM_GC_HeapInspection() {}
149 virtual VMOp_Type type() const { return VMOp_GC_HeapInspection; }
150 virtual bool skip_operation() const;
151 virtual bool doit_prologue();
152 virtual void doit();
153 };
156 class VM_GenCollectForAllocation: public VM_GC_Operation {
157 private:
158 HeapWord* _res;
159 size_t _size; // size of object to be allocated.
160 bool _tlab; // alloc is of a tlab.
161 public:
162 VM_GenCollectForAllocation(size_t size,
163 bool tlab,
164 unsigned int gc_count_before)
165 : VM_GC_Operation(gc_count_before, GCCause::_allocation_failure),
166 _size(size),
167 _tlab(tlab) {
168 _res = NULL;
169 }
170 ~VM_GenCollectForAllocation() {}
171 virtual VMOp_Type type() const { return VMOp_GenCollectForAllocation; }
172 virtual void doit();
173 HeapWord* result() const { return _res; }
174 };
177 // VM operation to invoke a collection of the heap as a
178 // GenCollectedHeap heap.
179 class VM_GenCollectFull: public VM_GC_Operation {
180 private:
181 int _max_level;
182 public:
183 VM_GenCollectFull(unsigned int gc_count_before,
184 unsigned int full_gc_count_before,
185 GCCause::Cause gc_cause,
186 int max_level)
187 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true /* full */),
188 _max_level(max_level) { }
189 ~VM_GenCollectFull() {}
190 virtual VMOp_Type type() const { return VMOp_GenCollectFull; }
191 virtual void doit();
192 };
194 class VM_GenCollectForPermanentAllocation: public VM_GC_Operation {
195 private:
196 HeapWord* _res;
197 size_t _size; // size of object to be allocated
198 public:
199 VM_GenCollectForPermanentAllocation(size_t size,
200 unsigned int gc_count_before,
201 unsigned int full_gc_count_before,
202 GCCause::Cause gc_cause)
203 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
204 _size(size) {
205 _res = NULL;
206 _gc_cause = gc_cause;
207 }
208 ~VM_GenCollectForPermanentAllocation() {}
209 virtual VMOp_Type type() const { return VMOp_GenCollectForPermanentAllocation; }
210 virtual void doit();
211 HeapWord* result() const { return _res; }
212 };
214 class SvcGCMarker : public StackObj {
215 private:
216 JvmtiGCMarker _jgcm;
217 public:
218 typedef enum { MINOR, FULL, OTHER } reason_type;
220 SvcGCMarker(reason_type reason ) {
221 VM_GC_Operation::notify_gc_begin(reason == FULL);
222 }
224 ~SvcGCMarker() {
225 VM_GC_Operation::notify_gc_end();
226 }
227 };
229 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_VMGCOPERATIONS_HPP