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) 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP
28 #ifndef SERIALGC
29 #include "runtime/thread.hpp"
30 #endif
32 class VoidClosure;
34 // A SuspendibleThreadSet is (obviously) a set of threads that can be
35 // suspended. A thread can join and later leave the set, and periodically
36 // yield. If some thread (not in the set) requests, via suspend_all, that
37 // the threads be suspended, then the requesting thread is blocked until
38 // all the threads in the set have yielded or left the set. (Threads may
39 // not enter the set when an attempted suspension is in progress.) The
40 // suspending thread later calls resume_all, allowing the suspended threads
41 // to continue.
43 class SuspendibleThreadSet {
44 Monitor* _m;
45 int _async;
46 bool _async_stop;
47 int _async_stopped;
48 bool _initialized;
49 double _suspend_all_start;
51 void initialize_work();
53 public:
54 SuspendibleThreadSet() : _initialized(false) {}
56 // Add the current thread to the set. May block if a suspension
57 // is in progress.
58 void join();
59 // Removes the current thread from the set.
60 void leave();
61 // Returns "true" iff an suspension is in progress.
62 bool should_yield() { return _async_stop; }
63 // Suspends the current thread if a suspension is in progress (for
64 // the duration of the suspension.)
65 void yield(const char* id);
66 // Return when all threads in the set are suspended.
67 void suspend_all();
68 // Allow suspended threads to resume.
69 void resume_all();
70 // Redundant initializations okay.
71 void initialize() {
72 // Double-check dirty read idiom.
73 if (!_initialized) initialize_work();
74 }
75 };
78 class ConcurrentGCThread: public NamedThread {
79 friend class VMStructs;
81 protected:
82 bool _should_terminate;
83 bool _has_terminated;
85 enum CGC_flag_type {
86 CGC_nil = 0x0,
87 CGC_dont_suspend = 0x1,
88 CGC_CGC_safepoint = 0x2,
89 CGC_VM_safepoint = 0x4
90 };
92 static int _CGC_flag;
94 static bool CGC_flag_is_set(int b) { return (_CGC_flag & b) != 0; }
95 static int set_CGC_flag(int b) { return _CGC_flag |= b; }
96 static int reset_CGC_flag(int b) { return _CGC_flag &= ~b; }
98 // All instances share this one set.
99 static SuspendibleThreadSet _sts;
101 // Create and start the thread (setting it's priority high.)
102 void create_and_start();
104 // Do initialization steps in the thread: record stack base and size,
105 // init thread local storage, set JNI handle block.
106 void initialize_in_thread();
108 // Wait until Universe::is_fully_initialized();
109 void wait_for_universe_init();
111 // Record that the current thread is terminating, and will do more
112 // concurrent work.
113 void terminate();
115 public:
116 // Constructor
118 ConcurrentGCThread();
119 ~ConcurrentGCThread() {} // Exists to call NamedThread destructor.
121 // Tester
122 bool is_ConcurrentGC_thread() const { return true; }
124 static void safepoint_synchronize();
125 static void safepoint_desynchronize();
127 // All overridings should probably do _sts::yield, but we allow
128 // overriding for distinguished debugging messages. Default is to do
129 // nothing.
130 virtual void yield() {}
132 bool should_yield() { return _sts.should_yield(); }
134 // they are prefixed by sts since there are already yield() and
135 // should_yield() (non-static) methods in this class and it was an
136 // easy way to differentiate them.
137 static void stsYield(const char* id);
138 static bool stsShouldYield();
139 static void stsJoin();
140 static void stsLeave();
142 };
144 // The SurrogateLockerThread is used by concurrent GC threads for
145 // manipulating Java monitors, in particular, currently for
146 // manipulating the pending_list_lock. XXX
147 class SurrogateLockerThread: public JavaThread {
148 friend class VMStructs;
149 public:
150 enum SLT_msg_type {
151 empty = 0, // no message
152 acquirePLL, // acquire pending list lock
153 releaseAndNotifyPLL // notify and release pending list lock
154 };
155 private:
156 // the following are shared with the CMSThread
157 SLT_msg_type _buffer; // communication buffer
158 Monitor _monitor; // monitor controlling buffer
159 BasicLock _basicLock; // used for PLL locking
161 public:
162 static SurrogateLockerThread* make(TRAPS);
164 SurrogateLockerThread();
166 bool is_hidden_from_external_view() const { return true; }
168 void loop(); // main method
170 void manipulatePLL(SLT_msg_type msg);
172 };
174 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP