Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1MMUTracker.hpp @ 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 | e1fdf4fd34dc |
| children | b81f3572f355 |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 579 | 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 // 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. | |
| 27 | |
| 28 /***** ALL TIMES ARE IN SECS!!!!!!! *****/ | |
| 29 | |
| 30 // this is the "interface" | |
|
549
fe3d7c11b4b7
6700941: G1: allocation spec missing for some G1 classes
apetrusenko
parents:
342
diff
changeset
|
31 class G1MMUTracker: public CHeapObj { |
| 342 | 32 protected: |
| 33 double _time_slice; | |
| 34 double _max_gc_time; // this is per time slice | |
| 35 | |
| 36 public: | |
| 37 G1MMUTracker(double time_slice, double max_gc_time); | |
| 38 | |
| 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; | |
| 42 | |
| 43 double max_gc_time() { | |
| 936 | 44 return _max_gc_time; |
| 342 | 45 } |
| 46 | |
| 47 inline bool now_max_gc(double current_time) { | |
| 48 return when_sec(current_time, max_gc_time()) < 0.00001; | |
| 49 } | |
| 50 | |
| 51 inline double when_max_gc_sec(double current_time) { | |
| 52 return when_sec(current_time, max_gc_time()); | |
| 53 } | |
| 54 | |
| 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 } | |
| 59 | |
| 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 }; | |
| 65 | |
|
549
fe3d7c11b4b7
6700941: G1: allocation spec missing for some G1 classes
apetrusenko
parents:
342
diff
changeset
|
66 class G1MMUTrackerQueueElem VALUE_OBJ_CLASS_SPEC { |
| 342 | 67 private: |
| 68 double _start_time; | |
| 69 double _end_time; | |
| 70 | |
| 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; } | |
| 75 | |
| 76 G1MMUTrackerQueueElem() { | |
| 77 _start_time = 0.0; | |
| 78 _end_time = 0.0; | |
| 79 } | |
| 80 | |
| 81 G1MMUTrackerQueueElem(double start_time, double end_time) { | |
| 82 _start_time = start_time; | |
| 83 _end_time = end_time; | |
| 84 } | |
| 85 }; | |
| 86 | |
| 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 }; | |
| 94 | |
| 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 | |
|
1088
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
936
diff
changeset
|
102 // the shortest gap between them and consolidate them. |
|
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
936
diff
changeset
|
103 // For now, we have taken the expedient alternative of forgetting |
|
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
936
diff
changeset
|
104 // the oldest entry in the event that +G1ForgetfulMMUTracker, thus |
|
3fc996d4edd2
6902303: G1: ScavengeALot should cause an incremental, rather than a full, collection
ysr
parents:
936
diff
changeset
|
105 // potentially violating MMU specs for some time thereafter. |
| 342 | 106 |
| 107 G1MMUTrackerQueueElem _array[QueueLength]; | |
| 108 int _head_index; | |
| 109 int _tail_index; | |
| 110 int _no_entries; | |
| 111 | |
| 112 inline int trim_index(int index) { | |
| 113 return (index + QueueLength) % QueueLength; | |
| 114 } | |
| 115 | |
| 116 void remove_expired_entries(double current_time); | |
| 117 double calculate_gc_time(double current_time); | |
| 118 | |
| 119 double longest_pause_internal(double current_time); | |
| 120 double when_internal(double current_time, double pause_time); | |
| 121 | |
| 122 public: | |
| 123 G1MMUTrackerQueue(double time_slice, double max_gc_time); | |
| 124 | |
| 125 virtual void add_pause(double start, double end, bool gc_thread); | |
| 126 | |
| 127 virtual double longest_pause(double current_time); | |
| 128 virtual double when_sec(double current_time, double pause_time); | |
| 129 }; |