Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1MMUTracker.cpp @ 2431:02f49b66361a
7026932: G1: No need to abort VM when card count cache expansion fails
Summary: Manage allocation/freeing of the card cache counts and epochs arrays directly so that an allocation failure while attempting to expand these arrays does not abort the JVM. Failure to expand these arrays is not fatal.
Reviewed-by: iveresov, tonyp
| author | johnc |
|---|---|
| date | Mon, 28 Mar 2011 10:58:54 -0700 |
| parents | f95d63e2154a |
| children | 20213c8a3c40 |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 1972 | 2 * Copyright (c) 2001, 2010, 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 if (G1PolicyVerbose > 1) { |
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101 warning("MMU Tracker Queue overflow. Replacing earliest entry."); |
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102 } |
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103 |
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104 _head_index = trim_index(_head_index + 1); |
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105 assert(_head_index == _tail_index, "Because we have a full circular buffer"); |
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106 _tail_index = trim_index(_tail_index + 1); |
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107 } else { |
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108 _head_index = trim_index(_head_index + 1); |
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109 ++_no_entries; |
| 342 | 110 } |
| 111 _array[_head_index] = G1MMUTrackerQueueElem(start, end); | |
| 112 } | |
| 113 | |
| 114 // basically the _internal call does not remove expired entries | |
| 115 // this is for trying things out in the future and a couple | |
| 116 // of other places (debugging) | |
| 117 | |
| 118 double G1MMUTrackerQueue::longest_pause(double current_time) { | |
| 119 if (_DISABLE_MMU) | |
| 120 return _max_gc_time; | |
| 121 | |
| 122 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
| 123 remove_expired_entries(current_time); | |
| 124 | |
| 125 return longest_pause_internal(current_time); | |
| 126 } | |
| 127 | |
| 128 double G1MMUTrackerQueue::longest_pause_internal(double current_time) { | |
| 129 double target_time = _max_gc_time; | |
| 130 | |
| 131 while( 1 ) { | |
| 132 double gc_time = | |
| 936 | 133 calculate_gc_time(current_time + target_time); |
| 342 | 134 double diff = target_time + gc_time - _max_gc_time; |
| 135 if (!is_double_leq_0(diff)) { | |
| 136 target_time -= diff; | |
| 137 if (is_double_leq_0(target_time)) { | |
| 138 target_time = -1.0; | |
| 139 break; | |
| 140 } | |
| 141 } else { | |
| 142 break; | |
| 143 } | |
| 144 } | |
| 145 | |
| 146 return target_time; | |
| 147 } | |
| 148 | |
| 149 // basically the _internal call does not remove expired entries | |
| 150 // this is for trying things out in the future and a couple | |
| 151 // of other places (debugging) | |
| 152 | |
| 153 double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) { | |
| 154 if (_DISABLE_MMU) | |
| 155 return 0.0; | |
| 156 | |
| 157 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
| 158 remove_expired_entries(current_time); | |
| 159 | |
| 160 return when_internal(current_time, pause_time); | |
| 161 } | |
| 162 | |
| 163 double G1MMUTrackerQueue::when_internal(double current_time, | |
| 164 double pause_time) { | |
| 165 // if the pause is over the maximum, just assume that it's the maximum | |
| 166 double adjusted_pause_time = | |
| 167 (pause_time > max_gc_time()) ? max_gc_time() : pause_time; | |
| 168 double earliest_end = current_time + adjusted_pause_time; | |
| 169 double limit = earliest_end - _time_slice; | |
| 170 double gc_time = calculate_gc_time(earliest_end); | |
| 171 double diff = gc_time + adjusted_pause_time - max_gc_time(); | |
| 172 if (is_double_leq_0(diff)) | |
| 173 return 0.0; | |
| 174 | |
| 175 int index = _tail_index; | |
| 176 while ( 1 ) { | |
| 177 G1MMUTrackerQueueElem *elem = &_array[index]; | |
| 178 if (elem->end_time() > limit) { | |
| 179 if (elem->start_time() > limit) | |
| 180 diff -= elem->duration(); | |
| 181 else | |
| 182 diff -= elem->end_time() - limit; | |
| 183 if (is_double_leq_0(diff)) | |
| 184 return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time; | |
| 185 } | |
| 186 index = trim_index(index+1); | |
| 187 guarantee(index != trim_index(_head_index + 1), "should not go past head"); | |
| 188 } | |
| 189 } |