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/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   } RegionData;
  70 
  71   RegionData* _region_data;
  72 
  73   uint _degenerated_cycles_in_a_row;
  74   uint _successful_cycles_in_a_row;
  75 
  76   double _cycle_start;
  77   double _last_cycle_end;
  78 
  79   size_t _gc_times_learned;
  80   intx _gc_time_penalties;
  81   TruncatedSeq* _gc_time_history;
  82 
  83   // There may be many threads that contend to set this flag
  84   ShenandoahSharedFlag _metaspace_oom;
  85 
  86   static int compare_by_garbage(RegionData a, RegionData b);
  87 
  88   virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
  89                                                      RegionData* data, size_t data_size,
  90                                                      size_t free) = 0;
  91 
  92   void adjust_penalty(intx step);
  93 
  94 public:
  95   ShenandoahHeuristics();
  96   virtual ~ShenandoahHeuristics();
  97 
  98   void record_metaspace_oom()     { _metaspace_oom.set(); }
  99   void clear_metaspace_oom()      { _metaspace_oom.unset(); }
 100   bool has_metaspace_oom() const  { return _metaspace_oom.is_set(); }
 101 
 102   virtual void record_cycle_start();
 103 
 104   virtual void record_cycle_end();
 105 
 106   virtual bool should_start_gc() const;
 107 
 108   virtual bool should_degenerate_cycle();
 109 
 110   virtual void record_success_concurrent();
 111 
 112   virtual void record_success_degenerated();
 113 
 114   virtual void record_success_full();
 115 
 116   virtual void record_allocation_failure_gc();
 117 
 118   virtual void record_requested_gc();
 119 
 120   virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
 121 
 122   virtual bool can_process_references();
 123   virtual bool should_process_references();
 124 
 125   virtual bool can_unload_classes();
 126   virtual bool can_unload_classes_normal();
 127   virtual bool should_unload_classes();
 128 
 129   virtual const char* name() = 0;
 130   virtual bool is_diagnostic() = 0;
 131   virtual bool is_experimental() = 0;
 132   virtual void initialize();
 133 
 134   double time_since_last_gc() const;
 135 };
 136 
 137 #endif // SHARE_VM_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP