Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1MMUTracker.cpp @ 1088:3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
Summary: ScavengeALot now causes an incremental (but possibly partially young, in the G1 sense) collection. Some such collections may be abandoned on account of MMU specs. Band-aided a native leak associated with abandoned pauses, as well as an MMU tracker overflow related to frequent scavenge events in the face of a large MMU denominator interval; the latter is protected by a product flag that defaults to false.
Reviewed-by: tonyp
| author | ysr |
|---|---|
| date | Thu, 19 Nov 2009 13:43:25 -0800 |
| parents | 89e0543e1737 |
| children | b81f3572f355 |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 948 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 * | |
| 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 | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 #include "incls/_precompiled.incl" | |
| 26 #include "incls/_g1MMUTracker.cpp.incl" | |
| 27 | |
| 28 #define _DISABLE_MMU 0 | |
| 29 | |
| 30 // can't rely on comparing doubles with tolerating a small margin for error | |
| 31 #define SMALL_MARGIN 0.0000001 | |
| 32 #define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN ) | |
| 33 #define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2)) | |
| 34 #define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1)) | |
| 35 | |
| 36 /***** ALL TIMES ARE IN SECS!!!!!!! *****/ | |
| 37 | |
| 38 G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) : | |
| 39 _time_slice(time_slice), | |
| 936 | 40 _max_gc_time(max_gc_time) { } |
| 342 | 41 |
| 42 G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) : | |
| 43 G1MMUTracker(time_slice, max_gc_time), | |
| 44 _head_index(0), | |
| 45 _tail_index(trim_index(_head_index+1)), | |
| 46 _no_entries(0) { } | |
| 47 | |
| 48 void G1MMUTrackerQueue::remove_expired_entries(double current_time) { | |
| 49 double limit = current_time - _time_slice; | |
| 50 while (_no_entries > 0) { | |
| 51 if (is_double_geq(limit, _array[_tail_index].end_time())) { | |
| 52 _tail_index = trim_index(_tail_index + 1); | |
| 53 --_no_entries; | |
| 54 } else | |
| 55 return; | |
| 56 } | |
| 57 guarantee(_no_entries == 0, "should have no entries in the array"); | |
| 58 } | |
| 59 | |
| 60 double G1MMUTrackerQueue::calculate_gc_time(double current_time) { | |
| 61 double gc_time = 0.0; | |
| 62 double limit = current_time - _time_slice; | |
| 63 for (int i = 0; i < _no_entries; ++i) { | |
| 64 int index = trim_index(_tail_index + i); | |
| 65 G1MMUTrackerQueueElem *elem = &_array[index]; | |
| 66 if (elem->end_time() > limit) { | |
| 67 if (elem->start_time() > limit) | |
| 68 gc_time += elem->duration(); | |
| 69 else | |
| 70 gc_time += elem->end_time() - limit; | |
| 71 } | |
| 72 } | |
| 73 return gc_time; | |
| 74 } | |
| 75 | |
| 76 void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) { | |
| 77 double longest_allowed = longest_pause_internal(start); | |
| 78 if (longest_allowed < 0.0) | |
| 79 longest_allowed = 0.0; | |
| 80 double duration = end - start; | |
| 81 | |
| 82 remove_expired_entries(end); | |
| 83 if (_no_entries == QueueLength) { | |
| 84 // OK, right now when we fill up we bomb out | |
| 85 // there are a few ways of dealing with this "gracefully" | |
| 86 // increase the array size (:-) | |
| 87 // remove the oldest entry (this might allow more GC time for | |
| 88 // the time slice than what's allowed) | |
|
1088
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
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diff
changeset
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89 // consolidate the two entries with the minimum gap between them |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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90 // (this might allow less GC time than what's allowed) |
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6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
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91 guarantee(NOT_PRODUCT(ScavengeALot ||) G1ForgetfulMMUTracker, |
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6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
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92 "array full, currently we can't recover unless +G1ForgetfulMMUTracker"); |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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93 // In the case where ScavengeALot is true, such overflow is not |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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94 // uncommon; in such cases, we can, without much loss of precision |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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95 // or performance (we are GC'ing most of the time anyway!), |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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96 // simply overwrite the oldest entry in the tracker: this |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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97 // is also the behaviour when G1ForgetfulMMUTracker is enabled. |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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98 _head_index = trim_index(_head_index + 1); |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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99 assert(_head_index == _tail_index, "Because we have a full circular buffer"); |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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100 _tail_index = trim_index(_tail_index + 1); |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
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101 } else { |
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3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
|
102 _head_index = trim_index(_head_index + 1); |
|
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
948
diff
changeset
|
103 ++_no_entries; |
| 342 | 104 } |
| 105 _array[_head_index] = G1MMUTrackerQueueElem(start, end); | |
| 106 } | |
| 107 | |
| 108 // basically the _internal call does not remove expired entries | |
| 109 // this is for trying things out in the future and a couple | |
| 110 // of other places (debugging) | |
| 111 | |
| 112 double G1MMUTrackerQueue::longest_pause(double current_time) { | |
| 113 if (_DISABLE_MMU) | |
| 114 return _max_gc_time; | |
| 115 | |
| 116 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
| 117 remove_expired_entries(current_time); | |
| 118 | |
| 119 return longest_pause_internal(current_time); | |
| 120 } | |
| 121 | |
| 122 double G1MMUTrackerQueue::longest_pause_internal(double current_time) { | |
| 123 double target_time = _max_gc_time; | |
| 124 | |
| 125 while( 1 ) { | |
| 126 double gc_time = | |
| 936 | 127 calculate_gc_time(current_time + target_time); |
| 342 | 128 double diff = target_time + gc_time - _max_gc_time; |
| 129 if (!is_double_leq_0(diff)) { | |
| 130 target_time -= diff; | |
| 131 if (is_double_leq_0(target_time)) { | |
| 132 target_time = -1.0; | |
| 133 break; | |
| 134 } | |
| 135 } else { | |
| 136 break; | |
| 137 } | |
| 138 } | |
| 139 | |
| 140 return target_time; | |
| 141 } | |
| 142 | |
| 143 // basically the _internal call does not remove expired entries | |
| 144 // this is for trying things out in the future and a couple | |
| 145 // of other places (debugging) | |
| 146 | |
| 147 double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) { | |
| 148 if (_DISABLE_MMU) | |
| 149 return 0.0; | |
| 150 | |
| 151 MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); | |
| 152 remove_expired_entries(current_time); | |
| 153 | |
| 154 return when_internal(current_time, pause_time); | |
| 155 } | |
| 156 | |
| 157 double G1MMUTrackerQueue::when_internal(double current_time, | |
| 158 double pause_time) { | |
| 159 // if the pause is over the maximum, just assume that it's the maximum | |
| 160 double adjusted_pause_time = | |
| 161 (pause_time > max_gc_time()) ? max_gc_time() : pause_time; | |
| 162 double earliest_end = current_time + adjusted_pause_time; | |
| 163 double limit = earliest_end - _time_slice; | |
| 164 double gc_time = calculate_gc_time(earliest_end); | |
| 165 double diff = gc_time + adjusted_pause_time - max_gc_time(); | |
| 166 if (is_double_leq_0(diff)) | |
| 167 return 0.0; | |
| 168 | |
| 169 int index = _tail_index; | |
| 170 while ( 1 ) { | |
| 171 G1MMUTrackerQueueElem *elem = &_array[index]; | |
| 172 if (elem->end_time() > limit) { | |
| 173 if (elem->start_time() > limit) | |
| 174 diff -= elem->duration(); | |
| 175 else | |
| 176 diff -= elem->end_time() - limit; | |
| 177 if (is_double_leq_0(diff)) | |
| 178 return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time; | |
| 179 } | |
| 180 index = trim_index(index+1); | |
| 181 guarantee(index != trim_index(_head_index + 1), "should not go past head"); | |
| 182 } | |
| 183 } |