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