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 typedef struct {
69 ShenandoahHeapRegion* _region;
70 size_t _garbage;
71 } RegionData;
72
73 ShenandoahGeneration* _generation;
74
75 // if (_generation->generation_mode() == GLOBAL) _region_data represents
76 // the results of most recently completed global marking pass
77 // if (_generation->generation_mode() == OLD) _region_data represents
78 // the results of most recently completed old-gen marking pass
79 // if (_generation->generation_mode() == YOUNG) _region_data represents
80 // the resulits of most recently completed young-gen marking pass
81 //
82 // Note that there is some redundancy represented in _region_data because
83 // each instance is an array large enough to hold all regions. However,
84 // any region in young-gen is not in old-gen. And any time we are
85 // making use of the GLOBAL data, there is no need to maintain the
86 // YOUNG or OLD data. Consider this redundancy of data structure to
87 // have negligible cost unless proven otherwise.
88 RegionData* _region_data;
89
90 uint _degenerated_cycles_in_a_row;
91 uint _successful_cycles_in_a_row;
92
93 size_t _guaranteed_gc_interval;
94
95 double _cycle_start;
96 double _last_cycle_end;
97
98 size_t _gc_times_learned;
99 intx _gc_time_penalties;
100 TruncatedSeq* _gc_time_history;
101
102 // There may be many threads that contend to set this flag
103 ShenandoahSharedFlag _metaspace_oom;
104
105 static int compare_by_garbage(RegionData a, RegionData b);
106
107 // TODO: We need to enhance this API to give visibility to accompanying old-gen evacuation effort.
108 // In the case that the old-gen evacuation effort is small or zero, the young-gen heuristics
109 // should feel free to dedicate increased efforts to young-gen evacuation.
110
111 virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
112 RegionData* data, size_t data_size,
113 size_t free) = 0;
114
115 void adjust_penalty(intx step);
116
117 bool in_generation(ShenandoahHeapRegion* region);
118
119 public:
120 ShenandoahHeuristics(ShenandoahGeneration* generation);
121 virtual ~ShenandoahHeuristics();
122
123 void record_metaspace_oom() { _metaspace_oom.set(); }
124 void clear_metaspace_oom() { _metaspace_oom.unset(); }
125 bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
126
127 void set_guaranteed_gc_interval(size_t guaranteed_gc_interval) {
128 _guaranteed_gc_interval = guaranteed_gc_interval;
129 }
130
131 virtual void record_cycle_start();
132
133 virtual void record_cycle_end();
134
135 virtual bool should_start_gc();
136
137 virtual bool should_degenerate_cycle();
138
139 virtual void record_success_concurrent();
140
141 virtual void record_success_degenerated();
142
143 virtual void record_success_full();
144
145 virtual void record_allocation_failure_gc();
146
147 virtual void record_requested_gc();
148
149 // Return true iff the chosen collection set includes at least one old-gen region.
150 virtual bool choose_collection_set(ShenandoahCollectionSet* collection_set, ShenandoahOldHeuristics* old_heuristics);
151
152 virtual bool can_unload_classes();
153 virtual bool can_unload_classes_normal();
154 virtual bool should_unload_classes();
155
156 virtual const char* name() = 0;
157 virtual bool is_diagnostic() = 0;
158 virtual bool is_experimental() = 0;
159 virtual void initialize();
160
161 double time_since_last_gc() const;
162 };
163
164 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP