src/hotspot/share/gc/shenandoah/shenandoahHeuristics.hpp
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     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_SHENANDOAHHEURISTICS_HPP
       
    25 #define SHARE_VM_GC_SHENANDOAH_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 #define SHENANDOAH_CHECK_FLAG_SET(name)                                     \
       
    58   do {                                                                      \
       
    59     if (!name) {                                                            \
       
    60       err_msg message("Heuristics needs -XX:+" #name " to work correctly"); \
       
    61       vm_exit_during_initialization("Error", message);                      \
       
    62     }                                                                       \
       
    63   } while (0)
       
    64 
       
    65 class ShenandoahCollectionSet;
       
    66 class ShenandoahHeapRegion;
       
    67 
       
    68 class ShenandoahHeuristics : public CHeapObj<mtGC> {
       
    69   static const intx Concurrent_Adjust   =  1; // recover from penalties
       
    70   static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
       
    71   static const intx Full_Penalty        = 20; // how much to penalize average GC duration history on Full GC
       
    72 
       
    73 protected:
       
    74   typedef struct {
       
    75     ShenandoahHeapRegion* _region;
       
    76     size_t _garbage;
       
    77     uint64_t _seqnum_last_alloc;
       
    78   } RegionData;
       
    79 
       
    80   bool _update_refs_early;
       
    81   bool _update_refs_adaptive;
       
    82 
       
    83   RegionData* _region_data;
       
    84   size_t _region_data_size;
       
    85 
       
    86   uint _degenerated_cycles_in_a_row;
       
    87   uint _successful_cycles_in_a_row;
       
    88 
       
    89   size_t _bytes_in_cset;
       
    90 
       
    91   double _cycle_start;
       
    92   double _last_cycle_end;
       
    93 
       
    94   size_t _gc_times_learned;
       
    95   size_t _gc_time_penalties;
       
    96   TruncatedSeq* _gc_time_history;
       
    97 
       
    98   // There may be many threads that contend to set this flag
       
    99   ShenandoahSharedFlag _metaspace_oom;
       
   100 
       
   101   static int compare_by_garbage(RegionData a, RegionData b);
       
   102   static int compare_by_garbage_then_alloc_seq_ascending(RegionData a, RegionData b);
       
   103   static int compare_by_alloc_seq_ascending(RegionData a, RegionData b);
       
   104   static int compare_by_alloc_seq_descending(RegionData a, RegionData b);
       
   105 
       
   106   RegionData* get_region_data_cache(size_t num);
       
   107 
       
   108   virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
       
   109                                                      RegionData* data, size_t data_size,
       
   110                                                      size_t free) = 0;
       
   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 void record_phase_time(ShenandoahPhaseTimings::Phase phase, double secs);
       
   129 
       
   130   virtual bool should_start_normal_gc() const;
       
   131 
       
   132   virtual bool should_start_update_refs();
       
   133 
       
   134   virtual bool should_start_traversal_gc();
       
   135 
       
   136   virtual bool can_do_traversal_gc();
       
   137 
       
   138   virtual bool should_degenerate_cycle();
       
   139 
       
   140   virtual void record_success_concurrent();
       
   141 
       
   142   virtual void record_success_degenerated();
       
   143 
       
   144   virtual void record_success_full();
       
   145 
       
   146   virtual void record_allocation_failure_gc();
       
   147 
       
   148   virtual void record_requested_gc();
       
   149 
       
   150   virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
       
   151 
       
   152   virtual bool can_process_references();
       
   153   virtual bool should_process_references();
       
   154 
       
   155   virtual bool can_unload_classes();
       
   156   virtual bool can_unload_classes_normal();
       
   157   virtual bool should_unload_classes();
       
   158 
       
   159   virtual const char* name() = 0;
       
   160   virtual bool is_diagnostic() = 0;
       
   161   virtual bool is_experimental() = 0;
       
   162   virtual void initialize();
       
   163 
       
   164   double time_since_last_gc() const;
       
   165 };
       
   166 
       
   167 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP