1 /*
2 * Copyright (c) 2016, Oracle and/or its affiliates. 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
27
28 #include "gc/g1/collectionSetChooser.hpp"
29 #include "memory/allocation.hpp"
30 #include "utilities/debug.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 class G1CollectedHeap;
34 class G1CollectorState;
35 class G1GCPhaseTimes;
36 class G1Policy;
37 class G1SurvivorRegions;
38 class HeapRegion;
39
40 class G1CollectionSet VALUE_OBJ_CLASS_SPEC {
41 G1CollectedHeap* _g1;
42 G1Policy* _policy;
43
44 CollectionSetChooser* _cset_chooser;
45
46 uint _eden_region_length;
47 uint _survivor_region_length;
48 uint _old_region_length;
49
50 // The actual collection set as a set of region indices.
51 // All entries in _collection_set_regions below _collection_set_cur_length are
52 // assumed to be valid entries.
53 // We assume that at any time there is at most only one writer and (one or more)
54 // concurrent readers. This means we are good with using storestore and loadload
55 // barriers on the writer and reader respectively only.
56 uint* _collection_set_regions;
57 volatile size_t _collection_set_cur_length;
58 size_t _collection_set_max_length;
59
60 // The number of bytes in the collection set before the pause. Set from
61 // the incrementally built collection set at the start of an evacuation
62 // pause, and incremented in finalize_old_part() when adding old regions
63 // (if any) to the collection set.
64 size_t _bytes_used_before;
65
66 size_t _recorded_rs_lengths;
67
68 // The associated information that is maintained while the incremental
69 // collection set is being built with young regions. Used to populate
70 // the recorded info for the evacuation pause.
71
72 enum CSetBuildType {
73 Active, // We are actively building the collection set
74 Inactive // We are not actively building the collection set
75 };
76
77 CSetBuildType _inc_build_state;
78
79 // The number of bytes in the incrementally built collection set.
80 // Used to set _collection_set_bytes_used_before at the start of
81 // an evacuation pause.
82 size_t _inc_bytes_used_before;
83
84 // The RSet lengths recorded for regions in the CSet. It is updated
85 // by the thread that adds a new region to the CSet. We assume that
86 // only one thread can be allocating a new CSet region (currently,
87 // it does so after taking the Heap_lock) hence no need to
88 // synchronize updates to this field.
89 size_t _inc_recorded_rs_lengths;
90
91 // A concurrent refinement thread periodically samples the young
92 // region RSets and needs to update _inc_recorded_rs_lengths as
93 // the RSets grow. Instead of having to synchronize updates to that
94 // field we accumulate them in this field and add it to
95 // _inc_recorded_rs_lengths_diffs at the start of a GC.
96 ssize_t _inc_recorded_rs_lengths_diffs;
97
98 // The predicted elapsed time it will take to collect the regions in
99 // the CSet. This is updated by the thread that adds a new region to
100 // the CSet. See the comment for _inc_recorded_rs_lengths about
101 // MT-safety assumptions.
102 double _inc_predicted_elapsed_time_ms;
103
104 // See the comment for _inc_recorded_rs_lengths_diffs.
105 double _inc_predicted_elapsed_time_ms_diffs;
106
107 G1CollectorState* collector_state();
108 G1GCPhaseTimes* phase_times();
109
110 double predict_region_elapsed_time_ms(HeapRegion* hr);
111
112 void verify_young_cset_indices() const NOT_DEBUG_RETURN;
113 public:
114 G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy);
115 ~G1CollectionSet();
116
117 // Initializes the collection set giving the maximum possible length of the collection set.
118 void initialize(uint max_region_length);
119
120 CollectionSetChooser* cset_chooser();
121
122 void init_region_lengths(uint eden_cset_region_length,
123 uint survivor_cset_region_length);
124
125 void set_recorded_rs_lengths(size_t rs_lengths);
126
127 uint region_length() const { return young_region_length() +
128 old_region_length(); }
129 uint young_region_length() const { return eden_region_length() +
130 survivor_region_length(); }
131
132 uint eden_region_length() const { return _eden_region_length; }
133 uint survivor_region_length() const { return _survivor_region_length; }
134 uint old_region_length() const { return _old_region_length; }
135
136 // Incremental collection set support
137
138 // Initialize incremental collection set info.
139 void start_incremental_building();
140
141 // Perform any final calculations on the incremental collection set fields
142 // before we can use them.
143 void finalize_incremental_building();
144
145 // Reset the contents of the collection set.
146 void clear();
147
148 // Iterate over the collection set, applying the given HeapRegionClosure on all of them.
149 // If may_be_aborted is true, iteration may be aborted using the return value of the
150 // called closure method.
151 void iterate(HeapRegionClosure* cl) const;
152
153 // Iterate over the collection set, applying the given HeapRegionClosure on all of them,
154 // trying to optimally spread out starting position of total_workers workers given the
155 // caller's worker_id.
156 void iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const;
157
158 // Stop adding regions to the incremental collection set.
159 void stop_incremental_building() { _inc_build_state = Inactive; }
160
161 size_t recorded_rs_lengths() { return _recorded_rs_lengths; }
162
163 size_t bytes_used_before() const {
164 return _bytes_used_before;
165 }
166
167 void reset_bytes_used_before() {
168 _bytes_used_before = 0;
169 }
170
171 // Choose a new collection set. Marks the chosen regions as being
172 // "in_collection_set".
173 double finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors);
174 void finalize_old_part(double time_remaining_ms);
175
176 // Add old region "hr" to the collection set.
177 void add_old_region(HeapRegion* hr);
178
179 // Update information about hr in the aggregated information for
180 // the incrementally built collection set.
181 void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);
182
183 // Add eden region to the collection set.
184 void add_eden_region(HeapRegion* hr);
185
186 // Add survivor region to the collection set.
187 void add_survivor_regions(HeapRegion* hr);
188
189 #ifndef PRODUCT
190 bool verify_young_ages();
191
192 void print(outputStream* st);
193 #endif // !PRODUCT
194
195 private:
196 // Update the incremental collection set information when adding a region.
197 void add_young_region_common(HeapRegion* hr);
198 };
199
200 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
201