1 /*
2 * Copyright (c) 2016, 2018, 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.
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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 "utilities/debug.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 class G1CollectedHeap;
33 class G1CollectorState;
34 class G1GCPhaseTimes;
35 class G1Policy;
36 class G1SurvivorRegions;
37 class HeapRegion;
38
39 class G1CollectionSet {
40 G1CollectedHeap* _g1h;
41 G1Policy* _policy;
42
43 CollectionSetChooser* _cset_chooser;
44
45 uint _eden_region_length;
46 uint _survivor_region_length;
47 uint _old_region_length;
48
49 // The actual collection set as a set of region indices.
50 // All entries in _collection_set_regions below _collection_set_cur_length are
51 // assumed to be valid entries.
52 // We assume that at any time there is at most only one writer and (one or more)
53 // concurrent readers. This means we are good with using storestore and loadload
54 // barriers on the writer and reader respectively only.
55 uint* _collection_set_regions;
56 volatile size_t _collection_set_cur_length;
57 size_t _collection_set_max_length;
58
59 // The number of bytes in the collection set before the pause. Set from
60 // the incrementally built collection set at the start of an evacuation
61 // pause, and incremented in finalize_old_part() when adding old regions
62 // (if any) to the collection set.
63 size_t _bytes_used_before;
64
65 size_t _recorded_rs_lengths;
66
67 // The associated information that is maintained while the incremental
68 // collection set is being built with young regions. Used to populate
69 // the recorded info for the evacuation pause.
70
71 enum CSetBuildType {
72 Active, // We are actively building the collection set
73 Inactive // We are not actively building the collection set
74 };
75
76 CSetBuildType _inc_build_state;
77
78 // The number of bytes in the incrementally built collection set.
79 // Used to set _collection_set_bytes_used_before at the start of
80 // an evacuation pause.
81 size_t _inc_bytes_used_before;
82
83 // The RSet lengths recorded for regions in the CSet. It is updated
84 // by the thread that adds a new region to the CSet. We assume that
85 // only one thread can be allocating a new CSet region (currently,
86 // it does so after taking the Heap_lock) hence no need to
87 // synchronize updates to this field.
88 size_t _inc_recorded_rs_lengths;
89
90 // A concurrent refinement thread periodically samples the young
91 // region RSets and needs to update _inc_recorded_rs_lengths as
92 // the RSets grow. Instead of having to synchronize updates to that
93 // field we accumulate them in this field and add it to
94 // _inc_recorded_rs_lengths_diffs at the start of a GC.
95 ssize_t _inc_recorded_rs_lengths_diffs;
96
97 // The predicted elapsed time it will take to collect the regions in
98 // the CSet. This is updated by the thread that adds a new region to
99 // the CSet. See the comment for _inc_recorded_rs_lengths about
100 // MT-safety assumptions.
101 double _inc_predicted_elapsed_time_ms;
102
103 // See the comment for _inc_recorded_rs_lengths_diffs.
104 double _inc_predicted_elapsed_time_ms_diffs;
105
106 G1CollectorState* collector_state();
107 G1GCPhaseTimes* phase_times();
108
109 double predict_region_elapsed_time_ms(HeapRegion* hr);
110
111 void verify_young_cset_indices() const NOT_DEBUG_RETURN;
112 public:
113 G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy);
114 ~G1CollectionSet();
115
116 // Initializes the collection set giving the maximum possible length of the collection set.
117 void initialize(uint max_region_length);
118
119 CollectionSetChooser* cset_chooser();
120
121 void init_region_lengths(uint eden_cset_region_length,
122 uint survivor_cset_region_length);
123
124 void set_recorded_rs_lengths(size_t rs_lengths);
125
126 uint region_length() const { return young_region_length() +
127 old_region_length(); }
128 uint young_region_length() const { return eden_region_length() +
129 survivor_region_length(); }
130
131 uint eden_region_length() const { return _eden_region_length; }
132 uint survivor_region_length() const { return _survivor_region_length; }
133 uint old_region_length() const { return _old_region_length; }
134
135 // Incremental collection set support
136
137 // Initialize incremental collection set info.
138 void start_incremental_building();
139
140 // Perform any final calculations on the incremental collection set fields
141 // before we can use them.
142 void finalize_incremental_building();
143
144 // Reset the contents of the collection set.
145 void clear();
146
147 // Iterate over the collection set, applying the given HeapRegionClosure on all of them.
148 // If may_be_aborted is true, iteration may be aborted using the return value of the
149 // called closure method.
150 void iterate(HeapRegionClosure* cl) const;
151
152 // Iterate over the collection set, applying the given HeapRegionClosure on all of them,
153 // trying to optimally spread out starting position of total_workers workers given the
154 // caller's worker_id.
155 void iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const;
156
157 // Stop adding regions to the incremental collection set.
158 void stop_incremental_building() { _inc_build_state = Inactive; }
159
160 size_t recorded_rs_lengths() { return _recorded_rs_lengths; }
161
162 size_t bytes_used_before() const {
163 return _bytes_used_before;
164 }
165
166 void reset_bytes_used_before() {
167 _bytes_used_before = 0;
168 }
169
170 // Choose a new collection set. Marks the chosen regions as being
171 // "in_collection_set".
172 double finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors);
173 void finalize_old_part(double time_remaining_ms);
174
175 // Add old region "hr" to the collection set.
176 void add_old_region(HeapRegion* hr);
177
178 // Update information about hr in the aggregated information for
179 // the incrementally built collection set.
180 void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);
181
182 // Add eden region to the collection set.
183 void add_eden_region(HeapRegion* hr);
184
185 // Add survivor region to the collection set.
186 void add_survivor_regions(HeapRegion* hr);
187
188 #ifndef PRODUCT
189 bool verify_young_ages();
190
191 void print(outputStream* st);
192 #endif // !PRODUCT
193
194 private:
195 // Update the incremental collection set information when adding a region.
196 void add_young_region_common(HeapRegion* hr);
197 };
198
199 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
200