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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
  27 
  28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
  29 #include "gc_implementation/shared/gcStats.hpp"
  30 #include "gc_implementation/shared/gcUtil.hpp"
  31 #include "gc_interface/gcCause.hpp"
  32 
  33 // This class keeps statistical information and computes the
  34 // optimal free space for both the young and old generation
  35 // based on current application characteristics (based on gc cost
  36 // and application footprint).
  37 //
  38 // It also computes an optimal tenuring threshold between the young
  39 // and old generations, so as to equalize the cost of collections
  40 // of those generations, as well as optimial survivor space sizes
  41 // for the young generation.
  42 //
  43 // While this class is specifically intended for a generational system
  44 // consisting of a young gen (containing an Eden and two semi-spaces)
  45 // and a tenured gen, as well as a perm gen for reflective data, it
  46 // makes NO references to specific generations.
  47 //
  48 // 05/02/2003 Update
  49 // The 1.5 policy makes use of data gathered for the costs of GC on
  50 // specific generations.  That data does reference specific
  51 // generation.  Also diagnostics specific to generations have
  52 // been added.
  53 
  54 // Forward decls
  55 class elapsedTimer;
  56 class GenerationSizer;
  57 
  58 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {
  59  friend class PSGCAdaptivePolicyCounters;
  60  private:
  61   // These values are used to record decisions made during the
  62   // policy.  For example, if the young generation was decreased
  63   // to decrease the GC cost of minor collections the value
  64   // decrease_young_gen_for_throughput_true is used.
  65 
  66   // Last calculated sizes, in bytes, and aligned
  67   // NEEDS_CLEANUP should use sizes.hpp,  but it works in ints, not size_t's
  68 
  69   // Time statistics
  70   AdaptivePaddedAverage* _avg_major_pause;
  71 
  72   // Footprint statistics
  73   AdaptiveWeightedAverage* _avg_base_footprint;
  74 
  75   // Statistical data gathered for GC
  76   GCStats _gc_stats;
  77 
  78   size_t _survivor_size_limit;   // Limit in bytes of survivor size
  79   const double _collection_cost_margin_fraction;
  80 
  81   // Variable for estimating the major and minor pause times.
  82   // These variables represent linear least-squares fits of
  83   // the data.
  84   //   major pause time vs. old gen size
  85   LinearLeastSquareFit* _major_pause_old_estimator;
  86   //   major pause time vs. young gen size
  87   LinearLeastSquareFit* _major_pause_young_estimator;
  88 
  89 
  90   // These record the most recent collection times.  They
  91   // are available as an alternative to using the averages
  92   // for making ergonomic decisions.
  93   double _latest_major_mutator_interval_seconds;
  94 
  95   const size_t _intra_generation_alignment; // alignment for eden, survivors
  96 
  97   const double _gc_minor_pause_goal_sec;    // goal for maximum minor gc pause
  98 
  99   // The amount of live data in the heap at the last full GC, used
 100   // as a baseline to help us determine when we need to perform the
 101   // next full GC.
 102   size_t _live_at_last_full_gc;
 103 
 104   // decrease/increase the old generation for minor pause time
 105   int _change_old_gen_for_min_pauses;
 106 
 107   // increase/decrease the young generation for major pause time
 108   int _change_young_gen_for_maj_pauses;
 109 
 110 
 111   // Flag indicating that the adaptive policy is ready to use
 112   bool _old_gen_policy_is_ready;
 113 
 114   // Changing the generation sizing depends on the data that is
 115   // gathered about the effects of changes on the pause times and
 116   // throughput.  These variable count the number of data points
 117   // gathered.  The policy may use these counters as a threshhold
 118   // for reliable data.
 119   julong _young_gen_change_for_major_pause_count;
 120 
 121   // To facilitate faster growth at start up, supplement the normal
 122   // growth percentage for the young gen eden and the
 123   // old gen space for promotion with these value which decay
 124   // with increasing collections.
 125   uint _young_gen_size_increment_supplement;
 126   uint _old_gen_size_increment_supplement;
 127 
 128   // The number of bytes absorbed from eden into the old gen by moving the
 129   // boundary over live data.
 130   size_t _bytes_absorbed_from_eden;
 131 
 132  private:
 133 
 134   // Accessors
 135   AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; }
 136   double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; }
 137 
 138   // Change the young generation size to achieve a minor GC pause time goal
 139   void adjust_for_minor_pause_time(bool is_full_gc,
 140                                    size_t* desired_promo_size_ptr,
 141                                    size_t* desired_eden_size_ptr);
 142   // Change the generation sizes to achieve a GC pause time goal
 143   // Returned sizes are not necessarily aligned.
 144   void adjust_for_pause_time(bool is_full_gc,
 145                          size_t* desired_promo_size_ptr,
 146                          size_t* desired_eden_size_ptr);
 147   // Change the generation sizes to achieve an application throughput goal
 148   // Returned sizes are not necessarily aligned.
 149   void adjust_for_throughput(bool is_full_gc,
 150                              size_t* desired_promo_size_ptr,
 151                              size_t* desired_eden_size_ptr);
 152   // Change the generation sizes to achieve minimum footprint
 153   // Returned sizes are not aligned.
 154   size_t adjust_promo_for_footprint(size_t desired_promo_size,
 155                                     size_t desired_total);
 156   size_t adjust_eden_for_footprint(size_t desired_promo_size,
 157                                    size_t desired_total);
 158 
 159   // Size in bytes for an increment or decrement of eden.
 160   virtual size_t eden_increment(size_t cur_eden, uint percent_change);
 161   virtual size_t eden_decrement(size_t cur_eden);
 162   size_t eden_decrement_aligned_down(size_t cur_eden);
 163   size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);
 164 
 165   // Size in bytes for an increment or decrement of the promotion area
 166   virtual size_t promo_increment(size_t cur_promo, uint percent_change);
 167   virtual size_t promo_decrement(size_t cur_promo);
 168   size_t promo_decrement_aligned_down(size_t cur_promo);
 169   size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);
 170 
 171   // Decay the supplemental growth additive.
 172   void decay_supplemental_growth(bool is_full_gc);
 173 
 174   // Returns a change that has been scaled down.  Result
 175   // is not aligned.  (If useful, move to some shared
 176   // location.)
 177   size_t scale_down(size_t change, double part, double total);
 178 
 179  protected:
 180   // Time accessors
 181 
 182   // Footprint accessors
 183   size_t live_space() const {
 184     return (size_t)(avg_base_footprint()->average() +
 185                     avg_young_live()->average() +
 186                     avg_old_live()->average());
 187   }
 188   size_t free_space() const {
 189     return _eden_size + _promo_size;
 190   }
 191 
 192   void set_promo_size(size_t new_size) {
 193     _promo_size = new_size;
 194   }
 195   void set_survivor_size(size_t new_size) {
 196     _survivor_size = new_size;
 197   }
 198 
 199   // Update estimators
 200   void update_minor_pause_old_estimator(double minor_pause_in_ms);
 201 
 202   virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }
 203 
 204  public:
 205   // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.
 206   size_t eden_increment_aligned_up(size_t cur_eden);
 207   size_t eden_increment_aligned_down(size_t cur_eden);
 208   size_t promo_increment_aligned_up(size_t cur_promo);
 209   size_t promo_increment_aligned_down(size_t cur_promo);
 210 
 211   virtual size_t eden_increment(size_t cur_eden);
 212   virtual size_t promo_increment(size_t cur_promo);
 213 
 214   // Accessors for use by performance counters
 215   AdaptivePaddedNoZeroDevAverage*  avg_promoted() const {
 216     return _gc_stats.avg_promoted();
 217   }
 218   AdaptiveWeightedAverage* avg_base_footprint() const {
 219     return _avg_base_footprint;
 220   }
 221 
 222   // Input arguments are initial free space sizes for young and old
 223   // generations, the initial survivor space size, the
 224   // alignment values and the pause & throughput goals.
 225   //
 226   // NEEDS_CLEANUP this is a singleton object
 227   PSAdaptiveSizePolicy(size_t init_eden_size,
 228                        size_t init_promo_size,
 229                        size_t init_survivor_size,
 230                        size_t intra_generation_alignment,
 231                        double gc_pause_goal_sec,
 232                        double gc_minor_pause_goal_sec,
 233                        uint gc_time_ratio);
 234 
 235   // Methods indicating events of interest to the adaptive size policy,
 236   // called by GC algorithms. It is the responsibility of users of this
 237   // policy to call these methods at the correct times!
 238   void major_collection_begin();
 239   void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);
 240 
 241   //
 242   void tenured_allocation(size_t size) {
 243     _avg_pretenured->sample(size);
 244   }
 245 
 246   // Accessors
 247   // NEEDS_CLEANUP   should use sizes.hpp
 248 
 249   size_t calculated_old_free_size_in_bytes() const {
 250     return (size_t)(_promo_size + avg_promoted()->padded_average());
 251   }
 252 
 253   size_t average_old_live_in_bytes() const {
 254     return (size_t) avg_old_live()->average();
 255   }
 256 
 257   size_t average_promoted_in_bytes() const {
 258     return (size_t)avg_promoted()->average();
 259   }
 260 
 261   size_t padded_average_promoted_in_bytes() const {
 262     return (size_t)avg_promoted()->padded_average();
 263   }
 264 
 265   int change_young_gen_for_maj_pauses() {
 266     return _change_young_gen_for_maj_pauses;
 267   }
 268   void set_change_young_gen_for_maj_pauses(int v) {
 269     _change_young_gen_for_maj_pauses = v;
 270   }
 271 
 272   int change_old_gen_for_min_pauses() {
 273     return _change_old_gen_for_min_pauses;
 274   }
 275   void set_change_old_gen_for_min_pauses(int v) {
 276     _change_old_gen_for_min_pauses = v;
 277   }
 278 
 279   // Return true if the old generation size was changed
 280   // to try to reach a pause time goal.
 281   bool old_gen_changed_for_pauses() {
 282     bool result = _change_old_gen_for_maj_pauses != 0 ||
 283                   _change_old_gen_for_min_pauses != 0;
 284     return result;
 285   }
 286 
 287   // Return true if the young generation size was changed
 288   // to try to reach a pause time goal.
 289   bool young_gen_changed_for_pauses() {
 290     bool result = _change_young_gen_for_min_pauses != 0 ||
 291                   _change_young_gen_for_maj_pauses != 0;
 292     return result;
 293   }
 294   // end flags for pause goal
 295 
 296   // Return true if the old generation size was changed
 297   // to try to reach a throughput goal.
 298   bool old_gen_changed_for_throughput() {
 299     bool result = _change_old_gen_for_throughput != 0;
 300     return result;
 301   }
 302 
 303   // Return true if the young generation size was changed
 304   // to try to reach a throughput goal.
 305   bool young_gen_changed_for_throughput() {
 306     bool result = _change_young_gen_for_throughput != 0;
 307     return result;
 308   }
 309 
 310   int decrease_for_footprint() { return _decrease_for_footprint; }
 311 
 312 
 313   // Accessors for estimators.  The slope of the linear fit is
 314   // currently all that is used for making decisions.
 315 
 316   LinearLeastSquareFit* major_pause_old_estimator() {
 317     return _major_pause_old_estimator;
 318   }
 319 
 320   LinearLeastSquareFit* major_pause_young_estimator() {
 321     return _major_pause_young_estimator;
 322   }
 323 
 324 
 325   virtual void clear_generation_free_space_flags();
 326 
 327   float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }
 328   float major_pause_young_slope() {
 329     return _major_pause_young_estimator->slope();
 330   }
 331   float major_collection_slope() { return _major_collection_estimator->slope();}
 332 
 333   bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }
 334 
 335   // Given the amount of live data in the heap, should we
 336   // perform a Full GC?
 337   bool should_full_GC(size_t live_in_old_gen);
 338 
 339   // Calculates optimal free space sizes for both the young and tenured
 340   // generations.  Stores results in _eden_size and _promo_size.
 341   // Takes current used space in all generations as input, as well
 342   // as an indication if a full gc has just been performed, for use
 343   // in deciding if an OOM error should be thrown.
 344   void compute_generations_free_space(size_t young_live,
 345                                      size_t eden_live,
 346                                      size_t old_live,
 347                                      size_t cur_eden,  // current eden in bytes
 348                                      size_t max_old_gen_size,
 349                                      size_t max_eden_size,
 350                                      bool   is_full_gc,
 351                                      GCCause::Cause gc_cause,
 352                                      CollectorPolicy* collector_policy);
 353 
 354   // Calculates new survivor space size;  returns a new tenuring threshold
 355   // value. Stores new survivor size in _survivor_size.
 356   uint compute_survivor_space_size_and_threshold(bool   is_survivor_overflow,
 357                                                  uint    tenuring_threshold,
 358                                                  size_t survivor_limit);
 359 
 360   // Return the maximum size of a survivor space if the young generation were of
 361   // size gen_size.
 362   size_t max_survivor_size(size_t gen_size) {
 363     // Never allow the target survivor size to grow more than MinSurvivorRatio
 364     // of the young generation size.  We cannot grow into a two semi-space
 365     // system, with Eden zero sized.  Even if the survivor space grows, from()
 366     // might grow by moving the bottom boundary "down" -- so from space will
 367     // remain almost full anyway (top() will be near end(), but there will be a
 368     // large filler object at the bottom).
 369     const size_t sz = gen_size / MinSurvivorRatio;
 370     const size_t alignment = _intra_generation_alignment;
 371     return sz > alignment ? align_size_down(sz, alignment) : alignment;
 372   }
 373 
 374   size_t live_at_last_full_gc() {
 375     return _live_at_last_full_gc;
 376   }
 377 
 378   size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }
 379   void   reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }
 380 
 381   void set_bytes_absorbed_from_eden(size_t val) {
 382     _bytes_absorbed_from_eden = val;
 383   }
 384 
 385   // Update averages that are always used (even
 386   // if adaptive sizing is turned off).
 387   void update_averages(bool is_survivor_overflow,
 388                        size_t survived,
 389                        size_t promoted);
 390 
 391   // Printing support
 392   virtual bool print_adaptive_size_policy_on(outputStream* st) const;
 393 };
 394 
 395 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP