Tue, 26 Jan 2010 16:52:29 -0800
6920090: G1: Disable ReduceInitialCardMarks at least until 6920109 is fixed
Summary: G1 now answers "no" to the query can_elide_initializing_store_barrier() in the product build. A debug flag allows alternate behaviour in debug builds.
Reviewed-by: iveresov, tonyp
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
25 // Keeps track of the GC work and decides when it is OK to do GC work
26 // and for how long so that the MMU invariants are maintained.
28 /***** ALL TIMES ARE IN SECS!!!!!!! *****/
30 // this is the "interface"
31 class G1MMUTracker: public CHeapObj {
32 protected:
33 double _time_slice;
34 double _max_gc_time; // this is per time slice
36 public:
37 G1MMUTracker(double time_slice, double max_gc_time);
39 virtual void add_pause(double start, double end, bool gc_thread) = 0;
40 virtual double longest_pause(double current_time) = 0;
41 virtual double when_sec(double current_time, double pause_time) = 0;
43 double max_gc_time() {
44 return _max_gc_time;
45 }
47 inline bool now_max_gc(double current_time) {
48 return when_sec(current_time, max_gc_time()) < 0.00001;
49 }
51 inline double when_max_gc_sec(double current_time) {
52 return when_sec(current_time, max_gc_time());
53 }
55 inline jlong when_max_gc_ms(double current_time) {
56 double when = when_max_gc_sec(current_time);
57 return (jlong) (when * 1000.0);
58 }
60 inline jlong when_ms(double current_time, double pause_time) {
61 double when = when_sec(current_time, pause_time);
62 return (jlong) (when * 1000.0);
63 }
64 };
66 class G1MMUTrackerQueueElem VALUE_OBJ_CLASS_SPEC {
67 private:
68 double _start_time;
69 double _end_time;
71 public:
72 inline double start_time() { return _start_time; }
73 inline double end_time() { return _end_time; }
74 inline double duration() { return _end_time - _start_time; }
76 G1MMUTrackerQueueElem() {
77 _start_time = 0.0;
78 _end_time = 0.0;
79 }
81 G1MMUTrackerQueueElem(double start_time, double end_time) {
82 _start_time = start_time;
83 _end_time = end_time;
84 }
85 };
87 // this is an implementation of the MMUTracker using a (fixed-size) queue
88 // that keeps track of all the recent pause times
89 class G1MMUTrackerQueue: public G1MMUTracker {
90 private:
91 enum PrivateConstants {
92 QueueLength = 64
93 };
95 // The array keeps track of all the pauses that fall within a time
96 // slice (the last time slice during which pauses took place).
97 // The data structure implemented is a circular queue.
98 // Head "points" to the most recent addition, tail to the oldest one.
99 // The array is of fixed size and I don't think we'll need more than
100 // two or three entries with the current behaviour of G1 pauses.
101 // If the array is full, an easy fix is to look for the pauses with
102 // the shortest gap between them and consolidate them.
103 // For now, we have taken the expedient alternative of forgetting
104 // the oldest entry in the event that +G1ForgetfulMMUTracker, thus
105 // potentially violating MMU specs for some time thereafter.
107 G1MMUTrackerQueueElem _array[QueueLength];
108 int _head_index;
109 int _tail_index;
110 int _no_entries;
112 inline int trim_index(int index) {
113 return (index + QueueLength) % QueueLength;
114 }
116 void remove_expired_entries(double current_time);
117 double calculate_gc_time(double current_time);
119 double longest_pause_internal(double current_time);
120 double when_internal(double current_time, double pause_time);
122 public:
123 G1MMUTrackerQueue(double time_slice, double max_gc_time);
125 virtual void add_pause(double start, double end, bool gc_thread);
127 virtual double longest_pause(double current_time);
128 virtual double when_sec(double current_time, double pause_time);
129 };