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_HEURISTICS_SHENANDOAHHEURISTICS_HPP
  25 #define SHARE_VM_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
  26 
  27 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
  28 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp"
  29 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp"
  30 #include "memory/allocation.hpp"
  31 #include "runtime/globals_extension.hpp"
  32 #include "runtime/java.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() const;
 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 start_choose_collection_set() {
 122   }
 123   virtual void end_choose_collection_set() {
 124   }
 125 
 126   virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
 127 
 128   virtual bool can_process_references();
 129   virtual bool should_process_references();
 130 
 131   virtual bool can_unload_classes();
 132   virtual bool can_unload_classes_normal();
 133   virtual bool should_unload_classes();
 134 
 135   virtual const char* name() = 0;
 136   virtual bool is_diagnostic() = 0;
 137   virtual bool is_experimental() = 0;
 138   virtual void initialize();
 139 
 140   double time_since_last_gc() const;
 141 };
 142 
 143 #endif // SHARE_VM_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP