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 G1CollectorPolicy;
35 class G1CollectorState;
36 class G1GCPhaseTimes;
37 class HeapRegion;
38
39 class G1CollectionSet VALUE_OBJ_CLASS_SPEC {
40 G1CollectedHeap* _g1;
41 G1CollectorPolicy* _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 head of the list (via "next_in_collection_set()") representing the
50 // current collection set. Set from the incrementally built collection
51 // set at the start of the pause.
52 HeapRegion* _head;
53
54 // The number of bytes in the collection set before the pause. Set from
55 // the incrementally built collection set at the start of an evacuation
56 // pause, and incremented in finalize_old_part() when adding old regions
57 // (if any) to the collection set.
58 size_t _bytes_used_before;
59
60 size_t _recorded_rs_lengths;
61
62 // The associated information that is maintained while the incremental
63 // collection set is being built with young regions. Used to populate
64 // the recorded info for the evacuation pause.
65
66 enum CSetBuildType {
67 Active, // We are actively building the collection set
68 Inactive // We are not actively building the collection set
69 };
70
71 CSetBuildType _inc_build_state;
72
73 // The head of the incrementally built collection set.
74 HeapRegion* _inc_head;
75
76 // The tail of the incrementally built collection set.
77 HeapRegion* _inc_tail;
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 public:
113 G1CollectionSet(G1CollectedHeap* g1h);
114 ~G1CollectionSet();
115
116 void set_policy(G1CollectorPolicy* g1p) {
117 assert(_policy == NULL, "should only initialize once");
118 _policy = g1p;
119 }
120
121 CollectionSetChooser* cset_chooser();
122
123 void init_region_lengths(uint eden_cset_region_length,
124 uint survivor_cset_region_length);
125
126 void set_recorded_rs_lengths(size_t rs_lengths);
127
128 uint region_length() const { return young_region_length() +
129 old_region_length(); }
130 uint young_region_length() const { return eden_region_length() +
131 survivor_region_length(); }
132
133 uint eden_region_length() const { return _eden_region_length; }
134 uint survivor_region_length() const { return _survivor_region_length; }
135 uint old_region_length() const { return _old_region_length; }
136
137 // Incremental CSet Support
138
139 // The head of the incrementally built collection set.
140 HeapRegion* inc_head() { return _inc_head; }
141
142 // The tail of the incrementally built collection set.
143 HeapRegion* inc_tail() { return _inc_tail; }
144
145 // Initialize incremental collection set info.
146 void start_incremental_building();
147
148 // Perform any final calculations on the incremental CSet fields
149 // before we can use them.
150 void finalize_incremental_building();
151
152 void clear_incremental() {
153 _inc_head = NULL;
154 _inc_tail = NULL;
155 }
156
157 // Stop adding regions to the incremental collection set
158 void stop_incremental_building() { _inc_build_state = Inactive; }
159
160 // The head of the list (via "next_in_collection_set()") representing the
161 // current collection set.
162 HeapRegion* head() { return _head; }
163
164 void clear_head() { _head = NULL; }
165
166 size_t recorded_rs_lengths() { return _recorded_rs_lengths; }
167
168 size_t bytes_used_before() const {
169 return _bytes_used_before;
170 }
171
172 void reset_bytes_used_before() {
173 _bytes_used_before = 0;
174 }
175
176 // Choose a new collection set. Marks the chosen regions as being
177 // "in_collection_set", and links them together. The head and number of
178 // the collection set are available via access methods.
179 double finalize_young_part(double target_pause_time_ms);
180 void finalize_old_part(double time_remaining_ms);
181
182 // Add old region "hr" to the CSet.
183 void add_old_region(HeapRegion* hr);
184
185 // Update information about hr in the aggregated information for
186 // the incrementally built collection set.
187 void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);
188
189 // Add hr to the LHS of the incremental collection set.
190 void add_eden_region(HeapRegion* hr);
191
192 // Add hr to the RHS of the incremental collection set.
193 void add_survivor_regions(HeapRegion* hr);
194
195 #ifndef PRODUCT
196 void print(HeapRegion* list_head, outputStream* st);
197 #endif // !PRODUCT
198
199 private:
200 // Update the incremental cset information when adding a region
201 // (should not be called directly).
202 void add_young_region_common(HeapRegion* hr);
203
204 };
205
206 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP
207