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 /*

  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

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

  * 2 along with this work; if not, write to the Free Software Foundation,

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

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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  */

 // This class keeps statistical information and computes the

 // size of the heap.

 // Forward decls

 class elapsedTimer;

 class CollectorPolicy;

 class AdaptiveSizePolicy : public CHeapObj {

  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 consequetive

   // 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 geneneration 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 threshhold

   // 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,

                                CollectorPolicy* collector_policy);

   // Printing support

   virtual bool print_adaptive_size_policy_on(outputStream* st) const;

   bool print_adaptive_size_policy_on(outputStream* st, int

                                   tenuring_threshold) const;

 };

 // Class that can be used to print information about the

 // adaptive size policy at intervals specified by

 // AdaptiveSizePolicyOutputInterval.  Only print information

 // if an adaptive size policy is in use.

 class AdaptiveSizePolicyOutput : StackObj {

   AdaptiveSizePolicy* _size_policy;

   bool _do_print;

   bool print_test(uint count) {

     // A count of zero is a special value that indicates that the

     // interval test should be ignored.  An interval is of zero is

     // a special value that indicates that the interval test should

     // always fail (never do the print based on the interval test).

     return PrintGCDetails &&

            UseAdaptiveSizePolicy &&

            (UseParallelGC || UseConcMarkSweepGC) &&

            (AdaptiveSizePolicyOutputInterval > 0) &&

            ((count == 0) ||

              ((count % AdaptiveSizePolicyOutputInterval) == 0));

   }

  public:

   // The special value of a zero count can be used to ignore

   // the count test.

   AdaptiveSizePolicyOutput(uint count) {

     if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {

       CollectedHeap* heap = Universe::heap();

       _size_policy = heap->size_policy();

       _do_print = print_test(count);

     } else {

       _size_policy = NULL;

       _do_print = false;

     }

   }

   AdaptiveSizePolicyOutput(AdaptiveSizePolicy* size_policy,

                            uint count) :

     _size_policy(size_policy) {

     if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {

       _do_print = print_test(count);

     } else {

       _do_print = false;

     }

   }

   ~AdaptiveSizePolicyOutput() {

     if (_do_print) {

       assert(UseAdaptiveSizePolicy, "Should not be in use");

       _size_policy->print_adaptive_size_policy_on(gclog_or_tty);

     }

   }

 };