rev 60584 : imported patch 8245511-ihop

   1 /*
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  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_GC_G1_G1IHOPCONTROL_HPP
  26 #define SHARE_GC_G1_G1IHOPCONTROL_HPP
  27 

  28 #include "memory/allocation.hpp"
  29 #include "utilities/numberSeq.hpp"
  30 
  31 class G1Predictions;
  32 class G1NewTracer;
  33 
  34 // Base class for algorithms that calculate the heap occupancy at which
  35 // concurrent marking should start. This heap usage threshold should be relative
  36 // to old gen size.
  37 class G1IHOPControl : public CHeapObj<mtGC> {
  38  protected:
  39   // The initial IHOP value relative to the target occupancy.
  40   double _initial_ihop_percent;
  41   // The target maximum occupancy of the heap. The target occupancy is the number
  42   // of bytes when marking should be finished and reclaim started.
  43   size_t _target_occupancy;
  44 
  45   // Most recent complete mutator allocation period in seconds.
  46   double _last_allocation_time_s;
  47   // Amount of bytes allocated during _last_allocation_time_s.
  48   size_t _last_allocated_bytes;
  49 
  50   // Initialize an instance with the initial IHOP value in percent. The target
  51   // occupancy will be updated at the first heap expansion.
  52   G1IHOPControl(double initial_ihop_percent);


  53 
  54   // Most recent time from the end of the concurrent start to the start of the first
  55   // mixed gc.
  56   virtual double last_marking_length_s() const = 0;
  57  public:
  58   virtual ~G1IHOPControl() { }
  59 
  60   // Get the current non-young occupancy at which concurrent marking should start.
  61   virtual size_t get_conc_mark_start_threshold() = 0;
  62 
  63   // Adjust target occupancy.
  64   virtual void update_target_occupancy(size_t new_target_occupancy);
  65   // Update information about time during which allocations in the Java heap occurred,
  66   // how large these allocations were in bytes, and an additional buffer.
  67   // The allocations should contain any amount of space made unusable for further
  68   // allocation, e.g. any waste caused by TLAB allocation, space at the end of
  69   // humongous objects that can not be used for allocation, etc.
  70   // Together with the target occupancy, this additional buffer should contain the
  71   // difference between old gen size and total heap size at the start of reclamation,
  72   // and space required for that reclamation.
  73   virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);
  74   // Update the time spent in the mutator beginning from the end of concurrent start to
  75   // the first mixed gc.
  76   virtual void update_marking_length(double marking_length_s) = 0;
  77 
  78   virtual void print();
  79   virtual void send_trace_event(G1NewTracer* tracer);
  80 };
  81 
  82 // The returned concurrent mark starting occupancy threshold is a fixed value
  83 // relative to the maximum heap size.
  84 class G1StaticIHOPControl : public G1IHOPControl {
  85   // Most recent mutator time between the end of concurrent mark to the start of the
  86   // first mixed gc.
  87   double _last_marking_length_s;
  88  protected:
  89   double last_marking_length_s() const { return _last_marking_length_s; }
  90  public:
  91   G1StaticIHOPControl(double ihop_percent);
  92 
  93   size_t get_conc_mark_start_threshold() {
  94     guarantee(_target_occupancy > 0, "Target occupancy must have been initialized.");
  95     return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0);
  96   }
  97 
  98   virtual void update_marking_length(double marking_length_s) {
  99    assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
 100     _last_marking_length_s = marking_length_s;
 101   }
 102 };
 103 
 104 // This algorithm tries to return a concurrent mark starting occupancy value that
 105 // makes sure that during marking the given target occupancy is never exceeded,
 106 // based on predictions of current allocation rate and time periods between
 107 // concurrent start and the first mixed gc.
 108 class G1AdaptiveIHOPControl : public G1IHOPControl {
 109   size_t _heap_reserve_percent; // Percentage of maximum heap capacity we should avoid to touch
 110   size_t _heap_waste_percent;   // Percentage of free heap that should be considered as waste.
 111 
 112   const G1Predictions * _predictor;
 113 
 114   TruncatedSeq _marking_times_s;
 115   TruncatedSeq _allocation_rate_s;
 116 
 117   // The most recent unrestrained size of the young gen. This is used as an additional
 118   // factor in the calculation of the threshold, as the threshold is based on
 119   // non-young gen occupancy at the end of GC. For the IHOP threshold, we need to
 120   // consider the young gen size during that time too.
 121   // Since we cannot know what young gen sizes are used in the future, we will just
 122   // use the current one. We expect that this one will be one with a fairly large size,
 123   // as there is no marking or mixed gc that could impact its size too much.
 124   size_t _last_unrestrained_young_size;
 125 
 126   // Get a new prediction bounded below by zero from the given sequence.
 127   double predict(TruncatedSeq const* seq) const;
 128 
 129   bool have_enough_data_for_prediction() const;
 130 
 131   // The "actual" target threshold the algorithm wants to keep during and at the
 132   // end of marking. This is typically lower than the requested threshold, as the
 133   // algorithm needs to consider restrictions by the environment.
 134   size_t actual_target_threshold() const;




 135  protected:
 136   virtual double last_marking_length_s() const { return _marking_times_s.last(); }
 137  public:
 138   G1AdaptiveIHOPControl(double ihop_percent,

 139                         G1Predictions const* predictor,
 140                         size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into.
 141                         size_t heap_waste_percent);  // The percentage of the free space in the heap that we think is not usable for allocation.
 142 
 143   virtual size_t get_conc_mark_start_threshold();
 144 
 145   virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);
 146   virtual void update_marking_length(double marking_length_s);
 147 
 148   virtual void print();
 149   virtual void send_trace_event(G1NewTracer* tracer);
 150 };
 151 
 152 #endif // SHARE_GC_G1_G1IHOPCONTROL_HPP
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