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/globalDefinitions.hpp"
31
32 class G1CollectedHeap;
33 class G1CollectorPolicy;
34 class G1CollectorState;
35 class G1GCPhaseTimes;
36 class HeapRegion;
37
38 class G1CollectionSet : public CHeapObj<mtGC> {
39 G1CollectedHeap* _g1;
40 G1CollectorPolicy* _g1p;
41
42 CollectionSetChooser* _cset_chooser;
43
44 uint _eden_region_length;
45 uint _survivor_region_length;
46 uint _old_region_length;
47
48 // The head of the list (via "next_in_collection_set()") representing the
49 // current collection set. Set from the incrementally built collection
50 // set at the start of the pause.
51 HeapRegion* _head;
52
53 // The number of bytes in the collection set before the pause. Set from
54 // the incrementally built collection set at the start of an evacuation
55 // pause, and incremented in finalize_old_cset_part() when adding old regions
56 // (if any) to the collection set.
57 size_t _bytes_used_before;
58
59 size_t _recorded_rs_lengths;
60
61 // The associated information that is maintained while the incremental
62 // collection set is being built with young regions. Used to populate
63 // the recorded info for the evacuation pause.
64
65 enum CSetBuildType {
66 Active, // We are actively building the collection set
67 Inactive // We are not actively building the collection set
68 };
69
70 CSetBuildType _inc_build_state;
71
72 // The head of the incrementally built collection set.
73 HeapRegion* _inc_head;
74
75 // The tail of the incrementally built collection set.
76 HeapRegion* _inc_tail;
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 public:
112 G1CollectionSet(G1CollectedHeap* g1h, G1CollectorPolicy* g1p);
113 ~G1CollectionSet();
114
115 CollectionSetChooser* cset_chooser();
116
117 void init_region_lengths(uint eden_cset_region_length,
118 uint survivor_cset_region_length);
119
120 void set_recorded_rs_lengths(size_t rs_lengths);
121
122 uint region_length() const { return young_region_length() +
123 old_region_length(); }
124 uint young_region_length() const { return eden_region_length() +
125 survivor_region_length(); }
126
127 uint eden_region_length() const { return _eden_region_length; }
128 uint survivor_region_length() const { return _survivor_region_length; }
129 uint old_region_length() const { return _old_region_length; }
130
131 // Incremental CSet Support
132
133 // The head of the incrementally built collection set.
134 HeapRegion* inc_head() { return _inc_head; }
135
136 // The tail of the incrementally built collection set.
137 HeapRegion* inc_tail() { return _inc_tail; }
138
139 // Initialize incremental collection set info.
140 void start_incremental_building();
141
142 // Perform any final calculations on the incremental CSet fields
143 // before we can use them.
144 void finalize_incremental_building();
145
146 void clear_incremental() {
147 _inc_head = NULL;
148 _inc_tail = NULL;
149 }
150
151 // Stop adding regions to the incremental collection set
152 void stop_incremental_building() { _inc_build_state = Inactive; }
153
154 // The head of the list (via "next_in_collection_set()") representing the
155 // current collection set.
156 HeapRegion* head() { return _head; }
157
158 void clear_head() { _head = NULL; }
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", and links them together. The head and number of
172 // the collection set are available via access methods.
173 double finalize_young_part(double target_pause_time_ms);
174 // XXX MGFIXME detgc!
175 virtual void finalize_old_part(double time_remaining_ms);
176
177 // Add old region "hr" to the CSet.
178 void add_old_region(HeapRegion* hr);
179
180 // Update information about hr in the aggregated information for
181 // the incrementally built collection set.
182 void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);
183
184 // Add hr to the LHS of the incremental collection set.
185 void add_eden_region(HeapRegion* hr);
186
187 // Add hr to the RHS of the incremental collection set.
188 void add_survivor_regions(HeapRegion* hr);
189
190 #ifndef PRODUCT
191 void print(HeapRegion* list_head, outputStream* st);
192 #endif // !PRODUCT
193
194 private:
195 // Update the incremental cset information when adding a region
196 // (should not be called directly).
197 void add_young_region_common(HeapRegion* hr);
198
199 };
200
201 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
202