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/shenandoahHeap.hpp"
 29 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
 30 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
 31 #include "memory/allocation.hpp"
 32 #include "runtime/globals_extension.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 class ShenandoahCollectionSet;
 59 class ShenandoahHeapRegion;
 60 
 61 class ShenandoahHeuristics : public CHeapObj<mtGC> {
 62   static const intx Concurrent_Adjust   = -1; // recover from penalties
 63   static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
 64   static const intx Full_Penalty        = 20; // how much to penalize average GC duration history on Full GC
 65 
 66 protected:
 67   typedef struct {
 68     ShenandoahHeapRegion* _region;
 69     size_t _garbage;
 70   } RegionData;
 71 
 72   RegionData* _region_data;
 73 
 74   uint _degenerated_cycles_in_a_row;
 75   uint _successful_cycles_in_a_row;
 76 
 77   double _cycle_start;
 78   double _last_cycle_end;
 79 
 80   size_t _gc_times_learned;
 81   intx _gc_time_penalties;
 82   TruncatedSeq* _gc_time_history;
 83 
 84   // There may be many threads that contend to set this flag
 85   ShenandoahSharedFlag _metaspace_oom;
 86 
 87   static int compare_by_garbage(RegionData a, RegionData b);
 88 
 89   virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
 90                                                      RegionData* data, size_t data_size,
 91                                                      size_t free) = 0;
 92 
 93   void adjust_penalty(intx step);
 94 
 95 public:
 96   ShenandoahHeuristics();
 97   virtual ~ShenandoahHeuristics();
 98 
 99   void record_metaspace_oom()     { _metaspace_oom.set(); }
100   void clear_metaspace_oom()      { _metaspace_oom.unset(); }
101   bool has_metaspace_oom() const  { return _metaspace_oom.is_set(); }
102 
103   virtual void record_cycle_start();
104 
105   virtual void record_cycle_end();
106 
107   virtual bool should_start_gc();
108 
109   virtual bool should_degenerate_cycle();
110 
111   virtual void record_success_concurrent();
112 
113   virtual void record_success_degenerated();
114 
115   virtual void record_success_full();
116 
117   virtual void record_allocation_failure_gc();
118 
119   virtual void record_requested_gc();
120 
121   virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
122 
123   virtual bool can_unload_classes();
124   virtual bool can_unload_classes_normal();
125   virtual bool should_unload_classes();
126 
127   virtual const char* name() = 0;
128   virtual bool is_diagnostic() = 0;
129   virtual bool is_experimental() = 0;
130   virtual void initialize();
131 
132   double time_since_last_gc() const;
133 };
134 
135 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP