1 /*
2 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP
26
27 #include "gc/shenandoah/shenandoahHeap.hpp"
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
60 class ShenandoahHeuristics : public CHeapObj<mtGC> {
61 static const intx Concurrent_Adjust = 1; // recover from penalties
62 static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
63 static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
64
65 protected:
66 typedef struct {
67 ShenandoahHeapRegion* _region;
68 size_t _garbage;
69 uint64_t _seqnum_last_alloc;
70 } RegionData;
71
72 bool _update_refs_early;
73 bool _update_refs_adaptive;
74
75 RegionData* _region_data;
76 size_t _region_data_size;
77
78 uint _degenerated_cycles_in_a_row;
79 uint _successful_cycles_in_a_row;
80
81 size_t _bytes_in_cset;
82
83 double _cycle_start;
84 double _last_cycle_end;
85
86 size_t _gc_times_learned;
87 size_t _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 static int compare_by_garbage_then_alloc_seq_ascending(RegionData a, RegionData b);
95 static int compare_by_alloc_seq_ascending(RegionData a, RegionData b);
96 static int compare_by_alloc_seq_descending(RegionData a, RegionData b);
97
98 RegionData* get_region_data_cache(size_t num);
99
100 virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
101 RegionData* data, size_t data_size,
102 size_t free) = 0;
103
104 public:
105 ShenandoahHeuristics();
106 virtual ~ShenandoahHeuristics();
107
108 void record_gc_start();
109
110 void record_gc_end();
111
112 void record_metaspace_oom() { _metaspace_oom.set(); }
113 void clear_metaspace_oom() { _metaspace_oom.unset(); }
114 bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
115
116 virtual void record_cycle_start();
117
118 virtual void record_cycle_end();
119
120 virtual void record_phase_time(ShenandoahPhaseTimings::Phase phase, double secs);
121
122 virtual bool should_start_normal_gc() const;
123
124 virtual bool should_start_update_refs();
125
126 virtual bool should_start_traversal_gc();
127
128 virtual bool can_do_traversal_gc();
129
130 virtual bool should_degenerate_cycle();
131
132 virtual void record_success_concurrent();
133
134 virtual void record_success_degenerated();
135
136 virtual void record_success_full();
137
138 virtual void record_allocation_failure_gc();
139
140 virtual void record_requested_gc();
141
142 virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
143
144 virtual bool can_process_references();
145 virtual bool should_process_references();
146
147 virtual bool can_unload_classes();
148 virtual bool can_unload_classes_normal();
149 virtual bool should_unload_classes();
150
151 virtual const char* name() = 0;
152 virtual bool is_diagnostic() = 0;
153 virtual bool is_experimental() = 0;
154 virtual void initialize();
155
156 double time_since_last_gc() const;
157 };
158
159 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP