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/heuristics/shenandoahSpaceInfo.hpp"
29 #include "gc/shenandoah/shenandoahHeap.hpp"
30 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
31 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
32 #include "memory/allocation.hpp"
33 #include "runtime/globals_extension.hpp"
34
35 #define SHENANDOAH_ERGO_DISABLE_FLAG(name) \
36 do { \
37 if (FLAG_IS_DEFAULT(name) && (name)) { \
38 log_info(gc)("Heuristics ergonomically sets -XX:-" #name); \
39 FLAG_SET_DEFAULT(name, false); \
40 } \
41 } while (0)
42
43 #define SHENANDOAH_ERGO_ENABLE_FLAG(name) \
44 do { \
45 if (FLAG_IS_DEFAULT(name) && !(name)) { \
46 log_info(gc)("Heuristics ergonomically sets -XX:+" #name); \
47 FLAG_SET_DEFAULT(name, true); \
48 } \
49 } while (0)
50
51 #define SHENANDOAH_ERGO_OVERRIDE_DEFAULT(name, value) \
52 do { \
53 if (FLAG_IS_DEFAULT(name)) { \
54 log_info(gc)("Heuristics ergonomically sets -XX:" #name "=" #value); \
55 FLAG_SET_DEFAULT(name, value); \
56 } \
57 } while (0)
58
59 class ShenandoahCollectionSet;
60 class ShenandoahHeapRegion;
61
62 /*
63 * Shenandoah heuristics are primarily responsible for deciding when to start
64 * a collection cycle and choosing which regions will be evacuated during the
65 * cycle.
66 */
67 class ShenandoahHeuristics : public CHeapObj<mtGC> {
68 static const intx Concurrent_Adjust = -1; // recover from penalties
69 static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
70 static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
71
72 protected:
73 typedef struct {
74 ShenandoahHeapRegion* _region;
75 size_t _garbage;
76 } RegionData;
77
78 // Source of information about the memory space managed by this heuristic
79 ShenandoahSpaceInfo* _space_info;
80
81 RegionData* _region_data;
82
83 double _cycle_start;
84 double _last_cycle_end;
85
86 size_t _gc_times_learned;
87 intx _gc_time_penalties;
88 TruncatedSeq* _gc_time_history;
89
90 // There may be many threads that contend to set this flag
91 ShenandoahSharedFlag _metaspace_oom;
92
93 static int compare_by_garbage(RegionData a, RegionData b);
94
95 virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
96 RegionData* data, size_t data_size,
97 size_t free) = 0;
98
99 void adjust_penalty(intx step);
100
101 public:
102 ShenandoahHeuristics(ShenandoahSpaceInfo* space_info);
103 virtual ~ShenandoahHeuristics();
104
105 void record_metaspace_oom() { _metaspace_oom.set(); }
106 void clear_metaspace_oom() { _metaspace_oom.unset(); }
107 bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
108
109 virtual void record_cycle_start();
110
111 virtual void record_cycle_end();
112
113 virtual bool should_start_gc();
114
115 virtual bool should_degenerate_cycle();
116
117 virtual void record_success_concurrent();
118
119 virtual void record_success_degenerated();
120
121 virtual void record_success_full();
122
123 virtual void record_allocation_failure_gc();
124
125 virtual void record_requested_gc();
126
127 virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
128
129 virtual bool can_unload_classes();
130 virtual bool should_unload_classes();
131
132 virtual const char* name() = 0;
133 virtual bool is_diagnostic() = 0;
134 virtual bool is_experimental() = 0;
135 virtual void initialize();
136
137 double time_since_last_gc() const;
138 };
139
140 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP