1 /*
2 * Copyright (c) 2018, 2019, Red Hat, Inc. 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_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
26 #define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
27
28 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
29 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/globals_extension.hpp"
32
33 #define SHENANDOAH_ERGO_DISABLE_FLAG(name) \
34 do { \
35 if (FLAG_IS_DEFAULT(name) && (name)) { \
36 log_info(gc)("Heuristics ergonomically sets -XX:-" #name); \
37 FLAG_SET_DEFAULT(name, false); \
38 } \
39 } while (0)
40
41 #define SHENANDOAH_ERGO_ENABLE_FLAG(name) \
42 do { \
43 if (FLAG_IS_DEFAULT(name) && !(name)) { \
44 log_info(gc)("Heuristics ergonomically sets -XX:+" #name); \
45 FLAG_SET_DEFAULT(name, true); \
46 } \
47 } while (0)
48
49 #define SHENANDOAH_ERGO_OVERRIDE_DEFAULT(name, value) \
50 do { \
51 if (FLAG_IS_DEFAULT(name)) { \
52 log_info(gc)("Heuristics ergonomically sets -XX:" #name "=" #value); \
53 FLAG_SET_DEFAULT(name, value); \
54 } \
55 } while (0)
56
57 class ShenandoahCollectionSet;
58 class ShenandoahHeapRegion;
59 class ShenandoahGeneration;
60 class ShenandoahOldHeuristics;
61
62 class ShenandoahHeuristics : public CHeapObj<mtGC> {
63 static const intx Concurrent_Adjust = -1; // recover from penalties
64 static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
65 static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
66
67 protected:
68 static const uint Moving_Average_Samples = 10; // Number of samples to store in moving averages
69
70 typedef struct {
71 ShenandoahHeapRegion* _region;
72 size_t _garbage;
73 } RegionData;
74
75 ShenandoahGeneration* _generation;
76
77 // if (_generation->generation_mode() == GLOBAL) _region_data represents
78 // the results of most recently completed global marking pass
79 // if (_generation->generation_mode() == OLD) _region_data represents
80 // the results of most recently completed old-gen marking pass
81 // if (_generation->generation_mode() == YOUNG) _region_data represents
82 // the results of most recently completed young-gen marking pass
83 //
84 // Note that there is some redundancy represented in _region_data because
85 // each instance is an array large enough to hold all regions. However,
86 // any region in young-gen is not in old-gen. And any time we are
87 // making use of the GLOBAL data, there is no need to maintain the
88 // YOUNG or OLD data. Consider this redundancy of data structure to
89 // have negligible cost unless proven otherwise.
90 RegionData* _region_data;
91
92 uint _degenerated_cycles_in_a_row;
93 uint _successful_cycles_in_a_row;
94
95 size_t _guaranteed_gc_interval;
96
97 double _cycle_start;
98 double _last_cycle_end;
99
100 size_t _gc_times_learned;
101 intx _gc_time_penalties;
102 TruncatedSeq* _gc_cycle_time_history;
103
104 // There may be many threads that contend to set this flag
105 ShenandoahSharedFlag _metaspace_oom;
106
107 static int compare_by_garbage(RegionData a, RegionData b);
108
109 // TODO: We need to enhance this API to give visibility to accompanying old-gen evacuation effort.
110 // In the case that the old-gen evacuation effort is small or zero, the young-gen heuristics
111 // should feel free to dedicate increased efforts to young-gen evacuation.
112
113 virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
114 RegionData* data, size_t data_size,
115 size_t free) = 0;
116
117 void adjust_penalty(intx step);
118
119 bool in_generation(ShenandoahHeapRegion* region);
120
121 size_t min_free_threshold();
122
123 public:
124 ShenandoahHeuristics(ShenandoahGeneration* generation);
125 virtual ~ShenandoahHeuristics();
126
127 void record_metaspace_oom() { _metaspace_oom.set(); }
128 void clear_metaspace_oom() { _metaspace_oom.unset(); }
129 bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
130
131 void set_guaranteed_gc_interval(size_t guaranteed_gc_interval) {
132 _guaranteed_gc_interval = guaranteed_gc_interval;
133 }
134
135 uint degenerated_cycles_in_a_row() {
136 return _degenerated_cycles_in_a_row;
137 }
138
139 virtual void record_cycle_start();
140
141 virtual void record_cycle_end();
142
143 virtual bool should_start_gc();
144
145 virtual bool should_degenerate_cycle();
146
147 virtual void record_success_concurrent(bool abbreviated);
148
149 virtual void record_success_degenerated();
150
151 virtual void record_success_full();
152
153 virtual void record_allocation_failure_gc();
154
155 virtual void record_requested_gc();
156
157 virtual void reset_gc_learning();
158
159 virtual size_t select_aged_regions(size_t old_available, size_t num_regions, bool preselected_regions[]);
160
161 virtual void choose_collection_set(ShenandoahCollectionSet* collection_set, ShenandoahOldHeuristics* old_heuristics);
162
163 virtual bool can_unload_classes();
164 virtual bool can_unload_classes_normal();
165 virtual bool should_unload_classes();
166
167 virtual const char* name() = 0;
168 virtual bool is_diagnostic() = 0;
169 virtual bool is_experimental() = 0;
170 virtual void initialize();
171
172 double elapsed_cycle_time() const;
173 };
174
175 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP