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_SHENANDOAHHEURISTICS_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP
27
28 #include "gc/shenandoah/shenandoahHeap.hpp"
29 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
30 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
31 #include "memory/allocation.hpp"
32 #include "runtime/globals.hpp"
33
34 #define SHENANDOAH_ERGO_DISABLE_FLAG(name) \
35 do { \
36 if (FLAG_IS_DEFAULT(name) && (name)) { \
37 log_info(gc)("Heuristics ergonomically sets -XX:-" #name); \
38 FLAG_SET_DEFAULT(name, false); \
39 } \
40 } while (0)
41
42 #define SHENANDOAH_ERGO_ENABLE_FLAG(name) \
43 do { \
44 if (FLAG_IS_DEFAULT(name) && !(name)) { \
45 log_info(gc)("Heuristics ergonomically sets -XX:+" #name); \
46 FLAG_SET_DEFAULT(name, true); \
47 } \
48 } while (0)
49
50 #define SHENANDOAH_ERGO_OVERRIDE_DEFAULT(name, value) \
51 do { \
52 if (FLAG_IS_DEFAULT(name)) { \
53 log_info(gc)("Heuristics ergonomically sets -XX:" #name "=" #value); \
54 FLAG_SET_DEFAULT(name, value); \
55 } \
56 } while (0)
57
58 #define SHENANDOAH_CHECK_FLAG_SET(name) \
59 do { \
60 if (!name) { \
61 err_msg message("Heuristics needs -XX:+" #name " to work correctly"); \
62 vm_exit_during_initialization("Error", message); \
63 } \
64 } while (0)
65
66 class ShenandoahCollectionSet;
67 class ShenandoahHeapRegion;
68
69 class ShenandoahHeuristics : public CHeapObj<mtGC> {
70 static const intx Concurrent_Adjust = -1; // recover from penalties
71 static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
72 static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
73
74 protected:
75 typedef struct {
76 ShenandoahHeapRegion* _region;
77 size_t _garbage;
78 uint64_t _seqnum_last_alloc;
79 } RegionData;
80
81 RegionData* _region_data;
82 size_t _region_data_size;
83
84 uint _degenerated_cycles_in_a_row;
85 uint _successful_cycles_in_a_row;
86
87 size_t _bytes_in_cset;
88
89 double _cycle_start;
90 double _last_cycle_end;
91
92 size_t _gc_times_learned;
93 intx _gc_time_penalties;
94 TruncatedSeq* _gc_time_history;
95
96 // There may be many threads that contend to set this flag
97 ShenandoahSharedFlag _metaspace_oom;
98
99 static int compare_by_garbage(RegionData a, RegionData b);
100 static int compare_by_garbage_then_alloc_seq_ascending(RegionData a, RegionData b);
101 static int compare_by_alloc_seq_ascending(RegionData a, RegionData b);
102 static int compare_by_alloc_seq_descending(RegionData a, RegionData b);
103
104 RegionData* get_region_data_cache(size_t num);
105
106 virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
107 RegionData* data, size_t data_size,
108 size_t free) = 0;
109
110 void adjust_penalty(intx step);
111
112 public:
113 ShenandoahHeuristics();
114 virtual ~ShenandoahHeuristics();
115
116 void record_gc_start();
117
118 void record_gc_end();
119
120 void record_metaspace_oom() { _metaspace_oom.set(); }
121 void clear_metaspace_oom() { _metaspace_oom.unset(); }
122 bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
123
124 virtual void record_cycle_start();
125
126 virtual void record_cycle_end();
127
128 virtual bool should_start_gc() const;
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_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP