1 /*

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

     4  *

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

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

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

    13  * accompanied this code).

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    24 

    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP

    27 

    28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"

    29 #include "runtime/timer.hpp"

    30 

    31 // This class keeps statistical information and computes the

    32 // size of the heap for the concurrent mark sweep collector.

    33 //

    34 // Cost for garbage collector include cost for

    35 //   minor collection

    36 //   concurrent collection

    37 //      stop-the-world component

    38 //      concurrent component

    39 //   major compacting collection

    40 //      uses decaying cost

    41 

    42 // Forward decls

    43 class elapsedTimer;

    44 

    45 class CMSAdaptiveSizePolicy : public AdaptiveSizePolicy {

    46  friend class CMSGCAdaptivePolicyCounters;

    47  friend class CMSCollector;

    48  private:

    49 

    50   // Total number of processors available

    51   int _processor_count;

    52   // Number of processors used by the concurrent phases of GC

    53   // This number is assumed to be the same for all concurrent

    54   // phases.

    55   int _concurrent_processor_count;

    56 

    57   // Time that the mutators run exclusive of a particular

    58   // phase.  For example, the time the mutators run excluding

    59   // the time during which the cms collector runs concurrently

    60   // with the mutators.

    61   //   Between end of most recent cms reset and start of initial mark

    62                 // This may be redundant

    63   double _latest_cms_reset_end_to_initial_mark_start_secs;

    64   //   Between end of the most recent initial mark and start of remark

    65   double _latest_cms_initial_mark_end_to_remark_start_secs;

    66   //   Between end of most recent collection and start of

    67   //   a concurrent collection

    68   double _latest_cms_collection_end_to_collection_start_secs;

    69   //   Times of the concurrent phases of the most recent

    70   //   concurrent collection

    71   double _latest_cms_concurrent_marking_time_secs;

    72   double _latest_cms_concurrent_precleaning_time_secs;

    73   double _latest_cms_concurrent_sweeping_time_secs;

    74   //   Between end of most recent STW MSC and start of next STW MSC

    75   double _latest_cms_msc_end_to_msc_start_time_secs;

    76   //   Between end of most recent MS and start of next MS

    77   //   This does not include any time spent during a concurrent

    78   // collection.

    79   double _latest_cms_ms_end_to_ms_start;

    80   //   Between start and end of the initial mark of the most recent

    81   // concurrent collection.

    82   double _latest_cms_initial_mark_start_to_end_time_secs;

    83   //   Between start and end of the remark phase of the most recent

    84   // concurrent collection

    85   double _latest_cms_remark_start_to_end_time_secs;

    86   //   Between start and end of the most recent MS STW marking phase

    87   double _latest_cms_ms_marking_start_to_end_time_secs;

    88 

    89   // Pause time timers

    90   static elapsedTimer _STW_timer;

    91   // Concurrent collection timer.  Used for total of all concurrent phases

    92   // during 1 collection cycle.

    93   static elapsedTimer _concurrent_timer;

    94 

    95   // When the size of the generation is changed, the size

    96   // of the change will rounded up or down (depending on the

    97   // type of change) by this value.

    98   size_t _generation_alignment;

    99 

   100   // If this variable is true, the size of the young generation

   101   // may be changed in order to reduce the pause(s) of the

   102   // collection of the tenured generation in order to meet the

   103   // pause time goal.  It is common to change the size of the

   104   // tenured generation in order to meet the pause time goal

   105   // for the tenured generation.  With the CMS collector for

   106   // the tenured generation, the size of the young generation

   107   // can have an significant affect on the pause times for collecting the

   108   // tenured generation.

   109   // This is a duplicate of a variable in PSAdaptiveSizePolicy.  It

   110   // is duplicated because it is not clear that it is general enough

   111   // to go into AdaptiveSizePolicy.

   112   int _change_young_gen_for_maj_pauses;

   113 

   114   // Variable that is set to true after a collection.

   115   bool _first_after_collection;

   116 

   117   // Fraction of collections that are of each type

   118   double concurrent_fraction() const;

   119   double STW_msc_fraction() const;

   120   double STW_ms_fraction() const;

   121 

   122   // This call cannot be put into the epilogue as long as some

   123   // of the counters can be set during concurrent phases.

   124   virtual void clear_generation_free_space_flags();

   125 

   126   void set_first_after_collection() { _first_after_collection = true; }

   127 

   128  protected:

   129   // Average of the sum of the concurrent times for

   130   // one collection in seconds.

   131   AdaptiveWeightedAverage* _avg_concurrent_time;

   132   // Average time between concurrent collections in seconds.

   133   AdaptiveWeightedAverage* _avg_concurrent_interval;

   134   // Average cost of the concurrent part of a collection

   135   // in seconds.

   136   AdaptiveWeightedAverage* _avg_concurrent_gc_cost;

   137 

   138   // Average of the initial pause of a concurrent collection in seconds.

   139   AdaptivePaddedAverage* _avg_initial_pause;

   140   // Average of the remark pause of a concurrent collection in seconds.

   141   AdaptivePaddedAverage* _avg_remark_pause;

   142 

   143   // Average of the stop-the-world (STW) (initial mark + remark)

   144   // times in seconds for concurrent collections.

   145   AdaptiveWeightedAverage* _avg_cms_STW_time;

   146   // Average of the STW collection cost for concurrent collections.

   147   AdaptiveWeightedAverage* _avg_cms_STW_gc_cost;

   148 

   149   // Average of the bytes free at the start of the sweep.

   150   AdaptiveWeightedAverage* _avg_cms_free_at_sweep;

   151   // Average of the bytes free at the end of the collection.

   152   AdaptiveWeightedAverage* _avg_cms_free;

   153   // Average of the bytes promoted between cms collections.

   154   AdaptiveWeightedAverage* _avg_cms_promo;

   155 

   156   // stop-the-world (STW) mark-sweep-compact

   157   // Average of the pause time in seconds for STW mark-sweep-compact

   158   // collections.

   159   AdaptiveWeightedAverage* _avg_msc_pause;

   160   // Average of the interval in seconds between STW mark-sweep-compact

   161   // collections.

   162   AdaptiveWeightedAverage* _avg_msc_interval;

   163   // Average of the collection costs for STW mark-sweep-compact

   164   // collections.

   165   AdaptiveWeightedAverage* _avg_msc_gc_cost;

   166 

   167   // Averages for mark-sweep collections.

   168   // The collection may have started as a background collection

   169   // that completes in a stop-the-world (STW) collection.

   170   // Average of the pause time in seconds for mark-sweep

   171   // collections.

   172   AdaptiveWeightedAverage* _avg_ms_pause;

   173   // Average of the interval in seconds between mark-sweep

   174   // collections.

   175   AdaptiveWeightedAverage* _avg_ms_interval;

   176   // Average of the collection costs for mark-sweep

   177   // collections.

   178   AdaptiveWeightedAverage* _avg_ms_gc_cost;

   179 

   180   // These variables contain a linear fit of

   181   // a generation size as the independent variable

   182   // and a pause time as the dependent variable.

   183   // For example _remark_pause_old_estimator

   184   // is a fit of the old generation size as the

   185   // independent variable and the remark pause

   186   // as the dependent variable.

   187   //   remark pause time vs. cms gen size

   188   LinearLeastSquareFit* _remark_pause_old_estimator;

   189   //   initial pause time vs. cms gen size

   190   LinearLeastSquareFit* _initial_pause_old_estimator;

   191   //   remark pause time vs. young gen size

   192   LinearLeastSquareFit* _remark_pause_young_estimator;

   193   //   initial pause time vs. young gen size

   194   LinearLeastSquareFit* _initial_pause_young_estimator;

   195 

   196   // Accessors

   197   int processor_count() const { return _processor_count; }

   198   int concurrent_processor_count() const { return _concurrent_processor_count; }

   199 

   200   AdaptiveWeightedAverage* avg_concurrent_time() const {

   201     return _avg_concurrent_time;

   202   }

   203 

   204   AdaptiveWeightedAverage* avg_concurrent_interval() const {

   205     return _avg_concurrent_interval;

   206   }

   207 

   208   AdaptiveWeightedAverage* avg_concurrent_gc_cost() const {

   209     return _avg_concurrent_gc_cost;

   210   }

   211 

   212   AdaptiveWeightedAverage* avg_cms_STW_time() const {

   213     return _avg_cms_STW_time;

   214   }

   215 

   216   AdaptiveWeightedAverage* avg_cms_STW_gc_cost() const {

   217     return _avg_cms_STW_gc_cost;

   218   }

   219 

   220   AdaptivePaddedAverage* avg_initial_pause() const {

   221     return _avg_initial_pause;

   222   }

   223 

   224   AdaptivePaddedAverage* avg_remark_pause() const {

   225     return _avg_remark_pause;

   226   }

   227 

   228   AdaptiveWeightedAverage* avg_cms_free() const {

   229     return _avg_cms_free;

   230   }

   231 

   232   AdaptiveWeightedAverage* avg_cms_free_at_sweep() const {

   233     return _avg_cms_free_at_sweep;

   234   }

   235 

   236   AdaptiveWeightedAverage* avg_msc_pause() const {

   237     return _avg_msc_pause;

   238   }

   239 

   240   AdaptiveWeightedAverage* avg_msc_interval() const {

   241     return _avg_msc_interval;

   242   }

   243 

   244   AdaptiveWeightedAverage* avg_msc_gc_cost() const {

   245     return _avg_msc_gc_cost;

   246   }

   247 

   248   AdaptiveWeightedAverage* avg_ms_pause() const {

   249     return _avg_ms_pause;

   250   }

   251 

   252   AdaptiveWeightedAverage* avg_ms_interval() const {

   253     return _avg_ms_interval;

   254   }

   255 

   256   AdaptiveWeightedAverage* avg_ms_gc_cost() const {

   257     return _avg_ms_gc_cost;

   258   }

   259 

   260   LinearLeastSquareFit* remark_pause_old_estimator() {

   261     return _remark_pause_old_estimator;

   262   }

   263   LinearLeastSquareFit* initial_pause_old_estimator() {

   264     return _initial_pause_old_estimator;

   265   }

   266   LinearLeastSquareFit* remark_pause_young_estimator() {

   267     return _remark_pause_young_estimator;

   268   }

   269   LinearLeastSquareFit* initial_pause_young_estimator() {

   270     return _initial_pause_young_estimator;

   271   }

   272 

   273   // These *slope() methods return the slope

   274   // m for the linear fit of an independent

   275   // variable vs. a dependent variable.  For

   276   // example

   277   //  remark_pause = m * old_generation_size + c

   278   // These may be used to determine if an

   279   // adjustment should be made to achieve a goal.

   280   // For example, if remark_pause_old_slope() is

   281   // positive, a reduction of the old generation

   282   // size has on average resulted in the reduction

   283   // of the remark pause.

   284   float remark_pause_old_slope() {

   285     return _remark_pause_old_estimator->slope();

   286   }

   287 

   288   float initial_pause_old_slope() {

   289     return _initial_pause_old_estimator->slope();

   290   }

   291 

   292   float remark_pause_young_slope() {

   293     return _remark_pause_young_estimator->slope();

   294   }

   295 

   296   float initial_pause_young_slope() {

   297     return _initial_pause_young_estimator->slope();

   298   }

   299 

   300   // Update estimators

   301   void update_minor_pause_old_estimator(double minor_pause_in_ms);

   302 

   303   // Fraction of processors used by the concurrent phases.

   304   double concurrent_processor_fraction();

   305 

   306   // Returns the total times for the concurrent part of the

   307   // latest collection in seconds.

   308   double concurrent_collection_time();

   309 

   310   // Return the total times for the concurrent part of the

   311   // latest collection in seconds where the times of the various

   312   // concurrent phases are scaled by the processor fraction used

   313   // during the phase.

   314   double scaled_concurrent_collection_time();

   315 

   316   // Dimensionless concurrent GC cost for all the concurrent phases.

   317   double concurrent_collection_cost(double interval_in_seconds);

   318 

   319   // Dimensionless GC cost

   320   double collection_cost(double pause_in_seconds, double interval_in_seconds);

   321 

   322   virtual GCPolicyKind kind() const { return _gc_cms_adaptive_size_policy; }

   323 

   324   virtual double time_since_major_gc() const;

   325 

   326   // This returns the maximum average for the concurrent, ms, and

   327   // msc collections.  This is meant to be used for the calculation

   328   // of the decayed major gc cost and is not in general the

   329   // average of all the different types of major collections.

   330   virtual double major_gc_interval_average_for_decay() const;

   331 

   332  public:

   333   CMSAdaptiveSizePolicy(size_t init_eden_size,

   334                         size_t init_promo_size,

   335                         size_t init_survivor_size,

   336                         double max_gc_minor_pause_sec,

   337                         double max_gc_pause_sec,

   338                         uint gc_cost_ratio);

   339 

   340   // The timers for the stop-the-world phases measure a total

   341   // stop-the-world time.  The timer is started and stopped

   342   // for each phase but is only reset after the final checkpoint.

   343   void checkpoint_roots_initial_begin();

   344   void checkpoint_roots_initial_end(GCCause::Cause gc_cause);

   345   void checkpoint_roots_final_begin();

   346   void checkpoint_roots_final_end(GCCause::Cause gc_cause);

   347 

   348   // Methods for gathering information about the

   349   // concurrent marking phase of the collection.

   350   // Records the mutator times and

   351   // resets the concurrent timer.

   352   void concurrent_marking_begin();

   353   // Resets concurrent phase timer in the begin methods and

   354   // saves the time for a phase in the end methods.

   355   void concurrent_marking_end();

   356   void concurrent_sweeping_begin();

   357   void concurrent_sweeping_end();

   358   // Similar to the above (e.g., concurrent_marking_end()) and

   359   // is used for both the precleaning an abortable precleaning

   360   // phases.

   361   void concurrent_precleaning_begin();

   362   void concurrent_precleaning_end();

   363   // Stops the concurrent phases time.  Gathers

   364   // information and resets the timer.

   365   void concurrent_phases_end(GCCause::Cause gc_cause,

   366                               size_t cur_eden,

   367                               size_t cur_promo);

   368 

   369   // Methods for gather information about STW Mark-Sweep-Compact

   370   void msc_collection_begin();

   371   void msc_collection_end(GCCause::Cause gc_cause);

   372 

   373   // Methods for gather information about Mark-Sweep done

   374   // in the foreground.

   375   void ms_collection_begin();

   376   void ms_collection_end(GCCause::Cause gc_cause);

   377 

   378   // Cost for a mark-sweep tenured gen collection done in the foreground

   379   double ms_gc_cost() const {

   380     return MAX2(0.0F, _avg_ms_gc_cost->average());

   381   }

   382 

   383   // Cost of collecting the tenured generation.  Includes

   384   // concurrent collection and STW collection costs

   385   double cms_gc_cost() const;

   386 

   387   // Cost of STW mark-sweep-compact tenured gen collection.

   388   double msc_gc_cost() const {

   389     return MAX2(0.0F, _avg_msc_gc_cost->average());

   390   }

   391 

   392   //

   393   double compacting_gc_cost() const {

   394     double result = MIN2(1.0, minor_gc_cost() + msc_gc_cost());

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

   396     return result;

   397   }

   398 

   399    // Restarts the concurrent phases timer.

   400    void concurrent_phases_resume();

   401 

   402    // Time beginning and end of the marking phase for

   403    // a synchronous MS collection.  A MS collection

   404    // that finishes in the foreground can have started

   405    // in the background.  These methods capture the

   406    // completion of the marking (after the initial

   407    // marking) that is done in the foreground.

   408    void ms_collection_marking_begin();

   409    void ms_collection_marking_end(GCCause::Cause gc_cause);

   410 

   411    static elapsedTimer* concurrent_timer_ptr() {

   412      return &_concurrent_timer;

   413    }

   414 

   415   AdaptiveWeightedAverage* avg_cms_promo() const {

   416     return _avg_cms_promo;

   417   }

   418 

   419   int change_young_gen_for_maj_pauses() {

   420     return _change_young_gen_for_maj_pauses;

   421   }

   422   void set_change_young_gen_for_maj_pauses(int v) {

   423     _change_young_gen_for_maj_pauses = v;

   424   }

   425 

   426   void clear_internal_time_intervals();

   427 

   428 

   429   // Either calculated_promo_size_in_bytes() or promo_size()

   430   // should be deleted.

   431   size_t promo_size() { return _promo_size; }

   432   void set_promo_size(size_t v) { _promo_size = v; }

   433 

   434   // Cost of GC for all types of collections.

   435   virtual double gc_cost() const;

   436 

   437   size_t generation_alignment() { return _generation_alignment; }

   438 

   439   virtual void compute_eden_space_size(size_t cur_eden,

   440                                        size_t max_eden_size);

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

   442   // value. Stores new survivor size in _survivor_size.

   443   virtual uint compute_survivor_space_size_and_threshold(

   444                                                 bool   is_survivor_overflow,

   445                                                 uint   tenuring_threshold,

   446                                                 size_t survivor_limit);

   447 

   448   virtual void compute_tenured_generation_free_space(size_t cur_tenured_free,

   449                                            size_t max_tenured_available,

   450                                            size_t cur_eden);

   451 

   452   size_t eden_decrement_aligned_down(size_t cur_eden);

   453   size_t eden_increment_aligned_up(size_t cur_eden);

   454 

   455   size_t adjust_eden_for_pause_time(size_t cur_eden);

   456   size_t adjust_eden_for_throughput(size_t cur_eden);

   457   size_t adjust_eden_for_footprint(size_t cur_eden);

   458 

   459   size_t promo_decrement_aligned_down(size_t cur_promo);

   460   size_t promo_increment_aligned_up(size_t cur_promo);

   461 

   462   size_t adjust_promo_for_pause_time(size_t cur_promo);

   463   size_t adjust_promo_for_throughput(size_t cur_promo);

   464   size_t adjust_promo_for_footprint(size_t cur_promo, size_t cur_eden);

   465 

   466   // Scale down the input size by the ratio of the cost to collect the

   467   // generation to the total GC cost.

   468   size_t scale_by_gen_gc_cost(size_t base_change, double gen_gc_cost);

   469 

   470   // Return the value and clear it.

   471   bool get_and_clear_first_after_collection();

   472 

   473   // Printing support

   474   virtual bool print_adaptive_size_policy_on(outputStream* st) const;

   475 };

   476 

   477 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP