Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1MMUTracker.cpp @ 6615:09aad8452938
7190310: Inlining WeakReference.get(), and hoisting $referent may lead to non-terminating loops
Summary: In C2 add software membar after load from Reference.referent field to prevent commoning of loads across safepoint since GC can change its value. In C1 always generate Reference.get() intrinsic.
Reviewed-by: roland, twisti, dholmes, johnc
author | kvn |
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date | Mon, 20 Aug 2012 09:58:58 -0700 |
parents | 20213c8a3c40 |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. |
342 | 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 * | |
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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. |
342 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/g1/g1MMUTracker.hpp" | |
27 #include "runtime/mutexLocker.hpp" | |
28 #include "utilities/ostream.hpp" | |
342 | 29 |
30 #define _DISABLE_MMU 0 | |
31 | |
32 // can't rely on comparing doubles with tolerating a small margin for error | |
33 #define SMALL_MARGIN 0.0000001 | |
34 #define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN ) | |
35 #define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2)) | |
36 #define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1)) | |
37 | |
38 /***** ALL TIMES ARE IN SECS!!!!!!! *****/ | |
39 | |
40 G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) : | |
41 _time_slice(time_slice), | |
936 | 42 _max_gc_time(max_gc_time) { } |
342 | 43 |
44 G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) : | |
45 G1MMUTracker(time_slice, max_gc_time), | |
46 _head_index(0), | |
47 _tail_index(trim_index(_head_index+1)), | |
48 _no_entries(0) { } | |
49 | |
50 void G1MMUTrackerQueue::remove_expired_entries(double current_time) { | |
51 double limit = current_time - _time_slice; | |
52 while (_no_entries > 0) { | |
53 if (is_double_geq(limit, _array[_tail_index].end_time())) { | |
54 _tail_index = trim_index(_tail_index + 1); | |
55 --_no_entries; | |
56 } else | |
57 return; | |
58 } | |
59 guarantee(_no_entries == 0, "should have no entries in the array"); | |
60 } | |
61 | |
62 double G1MMUTrackerQueue::calculate_gc_time(double current_time) { | |
63 double gc_time = 0.0; | |
64 double limit = current_time - _time_slice; | |
65 for (int i = 0; i < _no_entries; ++i) { | |
66 int index = trim_index(_tail_index + i); | |
67 G1MMUTrackerQueueElem *elem = &_array[index]; | |
68 if (elem->end_time() > limit) { | |
69 if (elem->start_time() > limit) | |
70 gc_time += elem->duration(); | |
71 else | |
72 gc_time += elem->end_time() - limit; | |
73 } | |
74 } | |
75 return gc_time; | |
76 } | |
77 | |
78 void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) { | |
79 double longest_allowed = longest_pause_internal(start); | |
80 if (longest_allowed < 0.0) | |
81 longest_allowed = 0.0; | |
82 double duration = end - start; | |
83 | |
84 remove_expired_entries(end); | |
85 if (_no_entries == QueueLength) { | |
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86 // OK, we've filled up the queue. There are a few ways |
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87 // of dealing with this "gracefully" |
342 | 88 // increase the array size (:-) |
89 // remove the oldest entry (this might allow more GC time for | |
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90 // the time slice than what's allowed) - this is what we |
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91 // currently do |
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92 // consolidate the two entries with the minimum gap between them |
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93 // (this might allow less GC time than what's allowed) |
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94 |
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95 // In the case where ScavengeALot is true, such overflow is not |
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96 // uncommon; in such cases, we can, without much loss of precision |
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97 // or performance (we are GC'ing most of the time anyway!), |
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98 // simply overwrite the oldest entry in the tracker. |
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99 |
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100 _head_index = trim_index(_head_index + 1); |
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101 assert(_head_index == _tail_index, "Because we have a full circular buffer"); |
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102 _tail_index = trim_index(_tail_index + 1); |
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103 } else { |
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104 _head_index = trim_index(_head_index + 1); |
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105 ++_no_entries; |
342 | 106 } |
107 _array[_head_index] = G1MMUTrackerQueueElem(start, end); | |
108 } | |
109 | |
110 // basically the _internal call does not remove expired entries | |
111 // this is for trying things out in the future and a couple | |
112 // of other places (debugging) | |
113 | |
114 double G1MMUTrackerQueue::longest_pause(double current_time) { | |
115 if (_DISABLE_MMU) | |
116 return _max_gc_time; | |
117 | |
118 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
119 remove_expired_entries(current_time); | |
120 | |
121 return longest_pause_internal(current_time); | |
122 } | |
123 | |
124 double G1MMUTrackerQueue::longest_pause_internal(double current_time) { | |
125 double target_time = _max_gc_time; | |
126 | |
127 while( 1 ) { | |
128 double gc_time = | |
936 | 129 calculate_gc_time(current_time + target_time); |
342 | 130 double diff = target_time + gc_time - _max_gc_time; |
131 if (!is_double_leq_0(diff)) { | |
132 target_time -= diff; | |
133 if (is_double_leq_0(target_time)) { | |
134 target_time = -1.0; | |
135 break; | |
136 } | |
137 } else { | |
138 break; | |
139 } | |
140 } | |
141 | |
142 return target_time; | |
143 } | |
144 | |
145 // basically the _internal call does not remove expired entries | |
146 // this is for trying things out in the future and a couple | |
147 // of other places (debugging) | |
148 | |
149 double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) { | |
150 if (_DISABLE_MMU) | |
151 return 0.0; | |
152 | |
153 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
154 remove_expired_entries(current_time); | |
155 | |
156 return when_internal(current_time, pause_time); | |
157 } | |
158 | |
159 double G1MMUTrackerQueue::when_internal(double current_time, | |
160 double pause_time) { | |
161 // if the pause is over the maximum, just assume that it's the maximum | |
162 double adjusted_pause_time = | |
163 (pause_time > max_gc_time()) ? max_gc_time() : pause_time; | |
164 double earliest_end = current_time + adjusted_pause_time; | |
165 double limit = earliest_end - _time_slice; | |
166 double gc_time = calculate_gc_time(earliest_end); | |
167 double diff = gc_time + adjusted_pause_time - max_gc_time(); | |
168 if (is_double_leq_0(diff)) | |
169 return 0.0; | |
170 | |
171 int index = _tail_index; | |
172 while ( 1 ) { | |
173 G1MMUTrackerQueueElem *elem = &_array[index]; | |
174 if (elem->end_time() > limit) { | |
175 if (elem->start_time() > limit) | |
176 diff -= elem->duration(); | |
177 else | |
178 diff -= elem->end_time() - limit; | |
179 if (is_double_leq_0(diff)) | |
180 return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time; | |
181 } | |
182 index = trim_index(index+1); | |
183 guarantee(index != trim_index(_head_index + 1), "should not go past head"); | |
184 } | |
185 } |