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 /*

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 // This class keeps statistical information and computes the

 // optimal free space for both the young and old generation

 // based on current application characteristics (based on gc cost

 // and application footprint).

 //

 // It also computes an optimal tenuring threshold between the young

 // and old generations, so as to equalize the cost of collections

 // of those generations, as well as optimial survivor space sizes

 // for the young generation.

 //

 // While this class is specifically intended for a generational system

 // consisting of a young gen (containing an Eden and two semi-spaces)

 // and a tenured gen, as well as a perm gen for reflective data, it

 // makes NO references to specific generations.

 //

 // 05/02/2003 Update

 // The 1.5 policy makes use of data gathered for the costs of GC on

 // specific generations.  That data does reference specific

 // generation.  Also diagnostics specific to generations have

 // been added.

 // Forward decls

 class elapsedTimer;

 class GenerationSizer;

 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {

  friend class PSGCAdaptivePolicyCounters;

  private:

   // These values are used to record decisions made during the

   // policy.  For example, if the young generation was decreased

   // to decrease the GC cost of minor collections the value

   // decrease_young_gen_for_throughput_true is used.

   // Last calculated sizes, in bytes, and aligned

   // NEEDS_CLEANUP should use sizes.hpp,  but it works in ints, not size_t's

   // Time statistics

   AdaptivePaddedAverage* _avg_major_pause;

   // Footprint statistics

   AdaptiveWeightedAverage* _avg_base_footprint;

   // Statistical data gathered for GC

   GCStats _gc_stats;

   size_t _survivor_size_limit;   // Limit in bytes of survivor size

   const double _collection_cost_margin_fraction;

   // Variable for estimating the major and minor pause times.

   // These variables represent linear least-squares fits of

   // the data.

   //   major pause time vs. old gen size

   LinearLeastSquareFit* _major_pause_old_estimator;

   //   major pause time vs. young gen size

   LinearLeastSquareFit* _major_pause_young_estimator;

   // These record the most recent collection times.  They

   // are available as an alternative to using the averages

   // for making ergonomic decisions.

   double _latest_major_mutator_interval_seconds;

   const size_t _intra_generation_alignment; // alignment for eden, survivors

   const double _gc_minor_pause_goal_sec;    // goal for maximum minor gc pause

   // The amount of live data in the heap at the last full GC, used

   // as a baseline to help us determine when we need to perform the

   // next full GC.

   size_t _live_at_last_full_gc;

   // decrease/increase the old generation for minor pause time

   int _change_old_gen_for_min_pauses;

   // increase/decrease the young generation for major pause time

   int _change_young_gen_for_maj_pauses;

   // Flag indicating that the adaptive policy is ready to use

   bool _old_gen_policy_is_ready;

   // Changing the generation sizing depends on the data that is

   // gathered about the effects of changes on the pause times and

   // throughput.  These variable count the number of data points

   // gathered.  The policy may use these counters as a threshhold

   // for reliable data.

   julong _young_gen_change_for_major_pause_count;

   // To facilitate faster growth at start up, supplement the normal

   // growth percentage for the young gen eden and the

   // old gen space for promotion with these value which decay

   // with increasing collections.

   uint _young_gen_size_increment_supplement;

   uint _old_gen_size_increment_supplement;

   // The number of bytes absorbed from eden into the old gen by moving the

   // boundary over live data.

   size_t _bytes_absorbed_from_eden;

  private:

   // Accessors

   AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; }

   double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; }

   // Change the young generation size to achieve a minor GC pause time goal

   void adjust_for_minor_pause_time(bool is_full_gc,

                                    size_t* desired_promo_size_ptr,

                                    size_t* desired_eden_size_ptr);

   // Change the generation sizes to achieve a GC pause time goal

   // Returned sizes are not necessarily aligned.

   void adjust_for_pause_time(bool is_full_gc,

                          size_t* desired_promo_size_ptr,

                          size_t* desired_eden_size_ptr);

   // Change the generation sizes to achieve an application throughput goal

   // Returned sizes are not necessarily aligned.

   void adjust_for_throughput(bool is_full_gc,

                              size_t* desired_promo_size_ptr,

                              size_t* desired_eden_size_ptr);

   // Change the generation sizes to achieve minimum footprint

   // Returned sizes are not aligned.

   size_t adjust_promo_for_footprint(size_t desired_promo_size,

                                     size_t desired_total);

   size_t adjust_eden_for_footprint(size_t desired_promo_size,

                                    size_t desired_total);

   // Size in bytes for an increment or decrement of eden.

   virtual size_t eden_increment(size_t cur_eden, uint percent_change);

   virtual size_t eden_decrement(size_t cur_eden);

   size_t eden_decrement_aligned_down(size_t cur_eden);

   size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);

   // Size in bytes for an increment or decrement of the promotion area

   virtual size_t promo_increment(size_t cur_promo, uint percent_change);

   virtual size_t promo_decrement(size_t cur_promo);

   size_t promo_decrement_aligned_down(size_t cur_promo);

   size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);

   // Decay the supplemental growth additive.

   void decay_supplemental_growth(bool is_full_gc);

   // Returns a change that has been scaled down.  Result

   // is not aligned.  (If useful, move to some shared

   // location.)

   size_t scale_down(size_t change, double part, double total);

  protected:

   // Time accessors

   // Footprint accessors

   size_t live_space() const {

     return (size_t)(avg_base_footprint()->average() +

                     avg_young_live()->average() +

                     avg_old_live()->average());

   }

   size_t free_space() const {

     return _eden_size + _promo_size;

   }

   void set_promo_size(size_t new_size) {

     _promo_size = new_size;

   }

   void set_survivor_size(size_t new_size) {

     _survivor_size = new_size;

   }

   // Update estimators

   void update_minor_pause_old_estimator(double minor_pause_in_ms);

   virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }

  public:

   // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.

   size_t eden_increment_aligned_up(size_t cur_eden);

   size_t eden_increment_aligned_down(size_t cur_eden);

   size_t promo_increment_aligned_up(size_t cur_promo);

   size_t promo_increment_aligned_down(size_t cur_promo);

   virtual size_t eden_increment(size_t cur_eden);

   virtual size_t promo_increment(size_t cur_promo);

   // Accessors for use by performance counters

   AdaptivePaddedNoZeroDevAverage*  avg_promoted() const {

     return _gc_stats.avg_promoted();

   }

   AdaptiveWeightedAverage* avg_base_footprint() const {

     return _avg_base_footprint;

   }

   // Input arguments are initial free space sizes for young and old

   // generations, the initial survivor space size, the

   // alignment values and the pause & throughput goals.

   //

   // NEEDS_CLEANUP this is a singleton object

   PSAdaptiveSizePolicy(size_t init_eden_size,

                        size_t init_promo_size,

                        size_t init_survivor_size,

                        size_t intra_generation_alignment,

                        double gc_pause_goal_sec,

                        double gc_minor_pause_goal_sec,

                        uint gc_time_ratio);

   // Methods indicating events of interest to the adaptive size policy,

   // called by GC algorithms. It is the responsibility of users of this

   // policy to call these methods at the correct times!

   void major_collection_begin();

   void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);

   //

   void tenured_allocation(size_t size) {

     _avg_pretenured->sample(size);

   }

   // Accessors

   // NEEDS_CLEANUP   should use sizes.hpp

   size_t calculated_old_free_size_in_bytes() const {

     return (size_t)(_promo_size + avg_promoted()->padded_average());

   }

   size_t average_old_live_in_bytes() const {

     return (size_t) avg_old_live()->average();

   }

   size_t average_promoted_in_bytes() const {

     return (size_t)avg_promoted()->average();

   }

   size_t padded_average_promoted_in_bytes() const {

     return (size_t)avg_promoted()->padded_average();

   }

   int change_young_gen_for_maj_pauses() {

     return _change_young_gen_for_maj_pauses;

   }

   void set_change_young_gen_for_maj_pauses(int v) {

     _change_young_gen_for_maj_pauses = v;

   }

   int change_old_gen_for_min_pauses() {

     return _change_old_gen_for_min_pauses;

   }

   void set_change_old_gen_for_min_pauses(int v) {

     _change_old_gen_for_min_pauses = v;

   }

   // Return true if the old generation size was changed

   // to try to reach a pause time goal.

   bool old_gen_changed_for_pauses() {

     bool result = _change_old_gen_for_maj_pauses != 0 ||

                   _change_old_gen_for_min_pauses != 0;

     return result;

   }

   // Return true if the young generation size was changed

   // to try to reach a pause time goal.

   bool young_gen_changed_for_pauses() {

     bool result = _change_young_gen_for_min_pauses != 0 ||

                   _change_young_gen_for_maj_pauses != 0;

     return result;

   }

   // end flags for pause goal

   // Return true if the old generation size was changed

   // to try to reach a throughput goal.

   bool old_gen_changed_for_throughput() {

     bool result = _change_old_gen_for_throughput != 0;

     return result;

   }

   // Return true if the young generation size was changed

   // to try to reach a throughput goal.

   bool young_gen_changed_for_throughput() {

     bool result = _change_young_gen_for_throughput != 0;

     return result;

   }

   int decrease_for_footprint() { return _decrease_for_footprint; }

   // Accessors for estimators.  The slope of the linear fit is

   // currently all that is used for making decisions.

   LinearLeastSquareFit* major_pause_old_estimator() {

     return _major_pause_old_estimator;

   }

   LinearLeastSquareFit* major_pause_young_estimator() {

     return _major_pause_young_estimator;

   }

   virtual void clear_generation_free_space_flags();

   float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }

   float major_pause_young_slope() {

     return _major_pause_young_estimator->slope();

   }

   float major_collection_slope() { return _major_collection_estimator->slope();}

   bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }

   // Given the amount of live data in the heap, should we

   // perform a Full GC?

   bool should_full_GC(size_t live_in_old_gen);

   // Calculates optimial free space sizes for both the old and young

   // generations.  Stores results in _eden_size and _promo_size.

   // Takes current used space in all generations as input, as well

   // as an indication if a full gc has just been performed, for use

   // in deciding if an OOM error should be thrown.

   void compute_generation_free_space(size_t young_live,

                                      size_t eden_live,

                                      size_t old_live,

                                      size_t perm_live,

                                      size_t cur_eden,  // current eden in bytes

                                      size_t max_old_gen_size,

                                      size_t max_eden_size,

                                      bool   is_full_gc,

                                      GCCause::Cause gc_cause,

                                      CollectorPolicy* collector_policy);

   // Calculates new survivor space size;  returns a new tenuring threshold

   // value. Stores new survivor size in _survivor_size.

   int compute_survivor_space_size_and_threshold(bool   is_survivor_overflow,

                                                 int    tenuring_threshold,

                                                 size_t survivor_limit);

   // Return the maximum size of a survivor space if the young generation were of

   // size gen_size.

   size_t max_survivor_size(size_t gen_size) {

     // Never allow the target survivor size to grow more than MinSurvivorRatio

     // of the young generation size.  We cannot grow into a two semi-space

     // system, with Eden zero sized.  Even if the survivor space grows, from()

     // might grow by moving the bottom boundary "down" -- so from space will

     // remain almost full anyway (top() will be near end(), but there will be a

     // large filler object at the bottom).

     const size_t sz = gen_size / MinSurvivorRatio;

     const size_t alignment = _intra_generation_alignment;

     return sz > alignment ? align_size_down(sz, alignment) : alignment;

   }

   size_t live_at_last_full_gc() {

     return _live_at_last_full_gc;

   }

   size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }

   void   reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }

   void set_bytes_absorbed_from_eden(size_t val) {

     _bytes_absorbed_from_eden = val;

   }

   // Update averages that are always used (even

   // if adaptive sizing is turned off).

   void update_averages(bool is_survivor_overflow,

                        size_t survived,

                        size_t promoted);

   // Printing support

   virtual bool print_adaptive_size_policy_on(outputStream* st) const;

 };