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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

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 * You should have received a copy of the GNU General Public License version

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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#include "gc/shared/gcCause.hpp"

#include "gc/shared/gcUtil.hpp"

#include "memory/allocation.hpp"

// This class keeps statistical information and computes the

// size of the heap.

// Forward decls

class elapsedTimer;

class SoftRefPolicy;

class AdaptiveSizePolicy : public CHeapObj<mtGC> {

 friend class GCAdaptivePolicyCounters;

 friend class PSGCAdaptivePolicyCounters;

 friend class CMSGCAdaptivePolicyCounters;

 protected:

  enum GCPolicyKind {

    _gc_adaptive_size_policy,

    _gc_ps_adaptive_size_policy,

    _gc_cms_adaptive_size_policy

  };

  virtual GCPolicyKind kind() const { return _gc_adaptive_size_policy; }

  enum SizePolicyTrueValues {

    decrease_old_gen_for_throughput_true = -7,

    decrease_young_gen_for_througput_true = -6,

    increase_old_gen_for_min_pauses_true = -5,

    decrease_old_gen_for_min_pauses_true = -4,

    decrease_young_gen_for_maj_pauses_true = -3,

    increase_young_gen_for_min_pauses_true = -2,

    increase_old_gen_for_maj_pauses_true = -1,

    decrease_young_gen_for_min_pauses_true = 1,

    decrease_old_gen_for_maj_pauses_true = 2,

    increase_young_gen_for_maj_pauses_true = 3,

    increase_old_gen_for_throughput_true = 4,

    increase_young_gen_for_througput_true = 5,

    decrease_young_gen_for_footprint_true = 6,

    decrease_old_gen_for_footprint_true = 7,

    decide_at_full_gc_true = 8

  };

  // Goal for the fraction of the total time during which application

  // threads run

  const double _throughput_goal;

  // Last calculated sizes, in bytes, and aligned

  size_t _eden_size;        // calculated eden free space in bytes

  size_t _promo_size;       // calculated cms gen free space in bytes

  size_t _survivor_size;    // calculated survivor size in bytes

  // This is a hint for the heap:  we've detected that GC times

  // are taking longer than GCTimeLimit allows.

  bool _gc_overhead_limit_exceeded;

  // Use for diagnostics only.  If UseGCOverheadLimit is false,

  // this variable is still set.

  bool _print_gc_overhead_limit_would_be_exceeded;

  // Count of consecutive GC that have exceeded the

  // GC time limit criterion

  uint _gc_overhead_limit_count;

  // This flag signals that GCTimeLimit is being exceeded

  // but may not have done so for the required number of consecutive

  // collections

  // Minor collection timers used to determine both

  // pause and interval times for collections

  static elapsedTimer _minor_timer;

  // Major collection timers, used to determine both

  // pause and interval times for collections

  static elapsedTimer _major_timer;

  // Time statistics

  AdaptivePaddedAverage*   _avg_minor_pause;

  AdaptiveWeightedAverage* _avg_minor_interval;

  AdaptiveWeightedAverage* _avg_minor_gc_cost;

  AdaptiveWeightedAverage* _avg_major_interval;

  AdaptiveWeightedAverage* _avg_major_gc_cost;

  // Footprint statistics

  AdaptiveWeightedAverage* _avg_young_live;

  AdaptiveWeightedAverage* _avg_eden_live;

  AdaptiveWeightedAverage* _avg_old_live;

  // Statistics for survivor space calculation for young generation

  AdaptivePaddedAverage*   _avg_survived;

  // Objects that have been directly allocated in the old generation

  AdaptivePaddedNoZeroDevAverage*   _avg_pretenured;

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

  // These variables represent linear least-squares fits of

  // the data.

  //   minor pause time vs. old gen size

  LinearLeastSquareFit* _minor_pause_old_estimator;

  //   minor pause time vs. young gen size

  LinearLeastSquareFit* _minor_pause_young_estimator;

  // Variables for estimating the major and minor collection costs

  //   minor collection time vs. young gen size

  LinearLeastSquareFit* _minor_collection_estimator;

  //   major collection time vs. cms gen size

  LinearLeastSquareFit* _major_collection_estimator;

  // These record the most recent collection times.  They

  // are available as an alternative to using the averages

  // for making ergonomic decisions.

  double _latest_minor_mutator_interval_seconds;

  // Allowed difference between major and minor GC times, used

  // for computing tenuring_threshold

  const double _threshold_tolerance_percent;

  const double _gc_pause_goal_sec; // Goal for maximum GC pause

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

  bool _young_gen_policy_is_ready;

  // Decrease/increase the young generation for minor pause time

  int _change_young_gen_for_min_pauses;

  // Decrease/increase the old generation for major pause time

  int _change_old_gen_for_maj_pauses;

  //   change old generation for throughput

  int _change_old_gen_for_throughput;

  //   change young generation for throughput

  int _change_young_gen_for_throughput;

  // Flag indicating that the policy would

  //   increase the tenuring threshold because of the total major GC cost

  //   is greater than the total minor GC cost

  bool _increment_tenuring_threshold_for_gc_cost;

  //   decrease the tenuring threshold because of the the total minor GC

  //   cost is greater than the total major GC cost

  bool _decrement_tenuring_threshold_for_gc_cost;

  //   decrease due to survivor size limit

  bool _decrement_tenuring_threshold_for_survivor_limit;

  //   decrease generation sizes for footprint

  int _decrease_for_footprint;

  // Set if the ergonomic decisions were made at a full GC.

  int _decide_at_full_gc;

  // 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 threshold

  // for reliable data.

  julong _young_gen_change_for_minor_throughput;

  julong _old_gen_change_for_major_throughput;

  // Accessors

  double gc_pause_goal_sec() const { return _gc_pause_goal_sec; }

  // The value returned is unitless:  it's the proportion of time

  // spent in a particular collection type.

  // An interval time will be 0.0 if a collection type hasn't occurred yet.

  // The 1.4.2 implementation put a floor on the values of major_gc_cost

  // and minor_gc_cost.  This was useful because of the way major_gc_cost

  // and minor_gc_cost was used in calculating the sizes of the generations.

  // Do not use a floor in this implementation because any finite value

  // will put a limit on the throughput that can be achieved and any

  // throughput goal above that limit will drive the generations sizes

  // to extremes.

  double major_gc_cost() const {

    return MAX2(0.0F, _avg_major_gc_cost->average());

  }

  // The value returned is unitless:  it's the proportion of time

  // spent in a particular collection type.

  // An interval time will be 0.0 if a collection type hasn't occurred yet.

  // The 1.4.2 implementation put a floor on the values of major_gc_cost

  // and minor_gc_cost.  This was useful because of the way major_gc_cost

  // and minor_gc_cost was used in calculating the sizes of the generations.

  // Do not use a floor in this implementation because any finite value

  // will put a limit on the throughput that can be achieved and any

  // throughput goal above that limit will drive the generations sizes

  // to extremes.

  double minor_gc_cost() const {

    return MAX2(0.0F, _avg_minor_gc_cost->average());

  }

  // Because we're dealing with averages, gc_cost() can be

  // larger than 1.0 if just the sum of the minor cost the

  // the major cost is used.  Worse than that is the

  // fact that the minor cost and the major cost each

  // tend toward 1.0 in the extreme of high GC costs.

  // Limit the value of gc_cost to 1.0 so that the mutator

  // cost stays non-negative.

  virtual double gc_cost() const {

    double result = MIN2(1.0, minor_gc_cost() + major_gc_cost());

    assert(result >= 0.0, "Both minor and major costs are non-negative");

    return result;

  }

  // Elapsed time since the last major collection.

  virtual double time_since_major_gc() const;

  // Average interval between major collections to be used

  // in calculating the decaying major GC cost.  An overestimate

  // of this time would be a conservative estimate because

  // this time is used to decide if the major GC cost

  // should be decayed (i.e., if the time since the last

  // major GC is long compared to the time returned here,

  // then the major GC cost will be decayed).  See the

  // implementations for the specifics.

  virtual double major_gc_interval_average_for_decay() const {

    return _avg_major_interval->average();

  }

  // Return the cost of the GC where the major GC cost

  // has been decayed based on the time since the last

  // major collection.

  double decaying_gc_cost() const;

  // Decay the major GC cost.  Use this only for decisions on

  // whether to adjust, not to determine by how much to adjust.

  // This approximation is crude and may not be good enough for the

  // latter.

  double decaying_major_gc_cost() const;

  // Return the mutator cost using the decayed

  // GC cost.

  double adjusted_mutator_cost() const {

    double result = 1.0 - decaying_gc_cost();

    assert(result >= 0.0, "adjusted mutator cost calculation is incorrect");

    return result;

  }

  virtual double mutator_cost() const {

    double result = 1.0 - gc_cost();

    assert(result >= 0.0, "mutator cost calculation is incorrect");

    return result;

  }

  bool young_gen_policy_is_ready() { return _young_gen_policy_is_ready; }

  void update_minor_pause_young_estimator(double minor_pause_in_ms);

  virtual void update_minor_pause_old_estimator(double minor_pause_in_ms) {

    // This is not meaningful for all policies but needs to be present

    // to use minor_collection_end() in its current form.

  }

  virtual size_t eden_increment(size_t cur_eden);

  virtual size_t eden_increment(size_t cur_eden, uint percent_change);

  virtual size_t eden_decrement(size_t cur_eden);

  virtual size_t promo_increment(size_t cur_eden);

  virtual size_t promo_increment(size_t cur_eden, uint percent_change);

  virtual size_t promo_decrement(size_t cur_eden);

  virtual void clear_generation_free_space_flags();

  int change_old_gen_for_throughput() const {

    return _change_old_gen_for_throughput;

  }

  void set_change_old_gen_for_throughput(int v) {

    _change_old_gen_for_throughput = v;

  }

  int change_young_gen_for_throughput() const {

    return _change_young_gen_for_throughput;

  }

  void set_change_young_gen_for_throughput(int v) {

    _change_young_gen_for_throughput = v;

  }

  int change_old_gen_for_maj_pauses() const {

    return _change_old_gen_for_maj_pauses;

  }

  void set_change_old_gen_for_maj_pauses(int v) {

    _change_old_gen_for_maj_pauses = v;

  }

  bool decrement_tenuring_threshold_for_gc_cost() const {

    return _decrement_tenuring_threshold_for_gc_cost;

  }

  void set_decrement_tenuring_threshold_for_gc_cost(bool v) {

    _decrement_tenuring_threshold_for_gc_cost = v;

  }

  bool increment_tenuring_threshold_for_gc_cost() const {

    return _increment_tenuring_threshold_for_gc_cost;

  }

  void set_increment_tenuring_threshold_for_gc_cost(bool v) {

    _increment_tenuring_threshold_for_gc_cost = v;

  }

  bool decrement_tenuring_threshold_for_survivor_limit() const {

    return _decrement_tenuring_threshold_for_survivor_limit;

  }

  void set_decrement_tenuring_threshold_for_survivor_limit(bool v) {

    _decrement_tenuring_threshold_for_survivor_limit = v;

  }

  // Return true if the policy suggested a change.

  bool tenuring_threshold_change() const;

 public:

  AdaptiveSizePolicy(size_t init_eden_size,

                     size_t init_promo_size,

                     size_t init_survivor_size,

                     double gc_pause_goal_sec,

                     uint gc_cost_ratio);

  bool is_gc_cms_adaptive_size_policy() {

    return kind() == _gc_cms_adaptive_size_policy;

  }

  bool is_gc_ps_adaptive_size_policy() {

    return kind() == _gc_ps_adaptive_size_policy;

  }

  AdaptivePaddedAverage*   avg_minor_pause() const { return _avg_minor_pause; }

  AdaptiveWeightedAverage* avg_minor_interval() const {

    return _avg_minor_interval;

  }

  AdaptiveWeightedAverage* avg_minor_gc_cost() const {

    return _avg_minor_gc_cost;

  }

  AdaptiveWeightedAverage* avg_major_gc_cost() const {

    return _avg_major_gc_cost;

  }

  AdaptiveWeightedAverage* avg_young_live() const { return _avg_young_live; }

  AdaptiveWeightedAverage* avg_eden_live() const { return _avg_eden_live; }

  AdaptiveWeightedAverage* avg_old_live() const { return _avg_old_live; }

  AdaptivePaddedAverage*  avg_survived() const { return _avg_survived; }

  AdaptivePaddedNoZeroDevAverage*  avg_pretenured() { return _avg_pretenured; }

  // 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!

  virtual void minor_collection_begin();

  virtual void minor_collection_end(GCCause::Cause gc_cause);

  virtual LinearLeastSquareFit* minor_pause_old_estimator() const {

    return _minor_pause_old_estimator;

  }

  LinearLeastSquareFit* minor_pause_young_estimator() {

    return _minor_pause_young_estimator;

  }

  LinearLeastSquareFit* minor_collection_estimator() {

    return _minor_collection_estimator;

  }

  LinearLeastSquareFit* major_collection_estimator() {

    return _major_collection_estimator;

  }

  float minor_pause_young_slope() {

    return _minor_pause_young_estimator->slope();

  }

  float minor_collection_slope() { return _minor_collection_estimator->slope();}

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

  float minor_pause_old_slope() {

    return _minor_pause_old_estimator->slope();

  }

  void set_eden_size(size_t new_size) {

    _eden_size = new_size;

  }

  void set_survivor_size(size_t new_size) {

    _survivor_size = new_size;

  }

  size_t calculated_eden_size_in_bytes() const {

    return _eden_size;

  }

  size_t calculated_promo_size_in_bytes() const {

    return _promo_size;

  }

  size_t calculated_survivor_size_in_bytes() const {

    return _survivor_size;

  }

  // This is a hint for the heap:  we've detected that gc times

  // are taking longer than GCTimeLimit allows.

  // Most heaps will choose to throw an OutOfMemoryError when

  // this occurs but it is up to the heap to request this information

  // of the policy

  bool gc_overhead_limit_exceeded() {

    return _gc_overhead_limit_exceeded;

  }

  void set_gc_overhead_limit_exceeded(bool v) {

    _gc_overhead_limit_exceeded = v;

  }

  // Tests conditions indicate the GC overhead limit is being approached.

  bool gc_overhead_limit_near() {

    return gc_overhead_limit_count() >=

        (AdaptiveSizePolicyGCTimeLimitThreshold - 1);

  }

  uint gc_overhead_limit_count() { return _gc_overhead_limit_count; }

  void reset_gc_overhead_limit_count() { _gc_overhead_limit_count = 0; }

  void inc_gc_overhead_limit_count() { _gc_overhead_limit_count++; }

  // accessors for flags recording the decisions to resize the

  // generations to meet the pause goal.

  int change_young_gen_for_min_pauses() const {

    return _change_young_gen_for_min_pauses;

  }

  void set_change_young_gen_for_min_pauses(int v) {

    _change_young_gen_for_min_pauses = v;

  }

  void set_decrease_for_footprint(int v) { _decrease_for_footprint = v; }

  int decrease_for_footprint() const { return _decrease_for_footprint; }

  int decide_at_full_gc() { return _decide_at_full_gc; }

  void set_decide_at_full_gc(int v) { _decide_at_full_gc = v; }

  // Check the conditions for an out-of-memory due to excessive GC time.

  // Set _gc_overhead_limit_exceeded if all the conditions have been met.

  void check_gc_overhead_limit(size_t young_live,

                               size_t eden_live,

                               size_t max_old_gen_size,

                               size_t max_eden_size,

                               bool   is_full_gc,

                               GCCause::Cause gc_cause,

                               SoftRefPolicy* soft_ref_policy);

  static bool should_update_promo_stats(GCCause::Cause cause) {

    return ((GCCause::is_user_requested_gc(cause)  &&

               UseAdaptiveSizePolicyWithSystemGC) ||

            GCCause::is_tenured_allocation_failure_gc(cause));

  }

  static bool should_update_eden_stats(GCCause::Cause cause) {

    return ((GCCause::is_user_requested_gc(cause)  &&

               UseAdaptiveSizePolicyWithSystemGC) ||

            GCCause::is_allocation_failure_gc(cause));

  }

  // Printing support

  virtual bool print() const;

  void print_tenuring_threshold(uint new_tenuring_threshold) const;

};