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  24 
  25 #ifndef SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP
  26 #define SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP
  27 
  28 #include "gc/shared/adaptiveSizePolicy.hpp"
  29 #include "gc/shared/gcCause.hpp"
  30 #include "gc/shared/gcStats.hpp"
  31 #include "gc/shared/gcUtil.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 optimal 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 
  57 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {
  58  friend class PSGCAdaptivePolicyCounters;
  59  private:
  60   // These values are used to record decisions made during the
  61   // policy.  For example, if the young generation was decreased
  62   // to decrease the GC cost of minor collections the value
  63   // decrease_young_gen_for_throughput_true is used.
  64 
  65   // Last calculated sizes, in bytes, and aligned
  66   // NEEDS_CLEANUP should use sizes.hpp,  but it works in ints, not size_t's
  67 
  68   // Time statistics
  69   AdaptivePaddedAverage* _avg_major_pause;
  70 
  71   // Footprint statistics
  72   AdaptiveWeightedAverage* _avg_base_footprint;
  73 
  74   // Statistical data gathered for GC
  75   GCStats _gc_stats;
  76 
  77   size_t _survivor_size_limit;   // Limit in bytes of survivor size
  78   const double _collection_cost_margin_fraction;
  79 
  80   // Variable for estimating the major and minor pause times.
  81   // These variables represent linear least-squares fits of
  82   // the data.
  83   //   major pause time vs. old gen size
  84   LinearLeastSquareFit* _major_pause_old_estimator;
  85   //   major pause time vs. young gen size
  86   LinearLeastSquareFit* _major_pause_young_estimator;
  87 
  88 
  89   // These record the most recent collection times.  They
  90   // are available as an alternative to using the averages
  91   // for making ergonomic decisions.
  92   double _latest_major_mutator_interval_seconds;
  93 
  94   const size_t _space_alignment; // alignment for eden, survivors
  95 
  96   const double _gc_minor_pause_goal_sec;    // goal for maximum minor gc pause
  97 
  98   // The amount of live data in the heap at the last full GC, used
  99   // as a baseline to help us determine when we need to perform the
 100   // next full GC.
 101   size_t _live_at_last_full_gc;
 102 
 103   // decrease/increase the old generation for minor pause time
 104   int _change_old_gen_for_min_pauses;
 105 
 106   // increase/decrease the young generation for major pause time
 107   int _change_young_gen_for_maj_pauses;
 108 
 109 
 110   // Flag indicating that the adaptive policy is ready to use
 111   bool _old_gen_policy_is_ready;
 112 
 113   // Changing the generation sizing depends on the data that is
 114   // gathered about the effects of changes on the pause times and
 115   // throughput.  These variable count the number of data points
 116   // gathered.  The policy may use these counters as a threshold
 117   // for reliable data.
 118   julong _young_gen_change_for_major_pause_count;
 119 
 120   // To facilitate faster growth at start up, supplement the normal
 121   // growth percentage for the young gen eden and the
 122   // old gen space for promotion with these value which decay
 123   // with increasing collections.
 124   uint _young_gen_size_increment_supplement;
 125   uint _old_gen_size_increment_supplement;
 126 
 127   // The number of bytes absorbed from eden into the old gen by moving the
 128   // boundary over live data.
 129   size_t _bytes_absorbed_from_eden;
 130 
 131  private:
 132 
 133   // Accessors
 134   AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; }
 135   double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; }
 136 
 137   void adjust_eden_for_minor_pause_time(bool is_full_gc,
 138                                    size_t* desired_eden_size_ptr);
 139   // Change the generation sizes to achieve a GC pause time goal
 140   // Returned sizes are not necessarily aligned.
 141   void adjust_promo_for_pause_time(bool is_full_gc,
 142                          size_t* desired_promo_size_ptr,
 143                          size_t* desired_eden_size_ptr);
 144   void adjust_eden_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_promo_for_throughput(bool is_full_gc,
 150                              size_t* desired_promo_size_ptr);
 151   void adjust_eden_for_throughput(bool is_full_gc,
 152                              size_t* desired_eden_size_ptr);
 153   // Change the generation sizes to achieve minimum footprint
 154   // Returned sizes are not aligned.
 155   size_t adjust_promo_for_footprint(size_t desired_promo_size,
 156                                     size_t desired_total);
 157   size_t adjust_eden_for_footprint(size_t desired_promo_size,
 158                                    size_t desired_total);
 159 
 160   // Size in bytes for an increment or decrement of eden.
 161   virtual size_t eden_increment(size_t cur_eden, uint percent_change);
 162   virtual size_t eden_decrement(size_t cur_eden);
 163   size_t eden_decrement_aligned_down(size_t cur_eden);
 164   size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);
 165 
 166   // Size in bytes for an increment or decrement of the promotion area
 167   virtual size_t promo_increment(size_t cur_promo, uint percent_change);
 168   virtual size_t promo_decrement(size_t cur_promo);
 169   size_t promo_decrement_aligned_down(size_t cur_promo);
 170   size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);
 171 
 172   // Returns a change that has been scaled down.  Result
 173   // is not aligned.  (If useful, move to some shared
 174   // location.)
 175   size_t scale_down(size_t change, double part, double total);
 176 
 177  protected:
 178   // Time accessors
 179 
 180   // Footprint accessors
 181   size_t live_space() const {
 182     return (size_t)(avg_base_footprint()->average() +
 183                     avg_young_live()->average() +
 184                     avg_old_live()->average());
 185   }
 186   size_t free_space() const {
 187     return _eden_size + _promo_size;
 188   }
 189 
 190   void set_promo_size(size_t new_size) {
 191     _promo_size = new_size;
 192   }
 193   void set_survivor_size(size_t new_size) {
 194     _survivor_size = new_size;
 195   }
 196 
 197   // Update estimators
 198   void update_minor_pause_old_estimator(double minor_pause_in_ms);
 199 
 200   virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }
 201 
 202  public:
 203   // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.
 204   size_t eden_increment_aligned_up(size_t cur_eden);
 205   size_t eden_increment_aligned_down(size_t cur_eden);
 206   size_t promo_increment_aligned_up(size_t cur_promo);
 207   size_t promo_increment_aligned_down(size_t cur_promo);
 208 
 209   virtual size_t eden_increment(size_t cur_eden);
 210   virtual size_t promo_increment(size_t cur_promo);
 211 
 212   // Accessors for use by performance counters
 213   AdaptivePaddedNoZeroDevAverage*  avg_promoted() const {
 214     return _gc_stats.avg_promoted();
 215   }
 216   AdaptiveWeightedAverage* avg_base_footprint() const {
 217     return _avg_base_footprint;
 218   }
 219 
 220   // Input arguments are initial free space sizes for young and old
 221   // generations, the initial survivor space size, the
 222   // alignment values and the pause & throughput goals.
 223   //
 224   // NEEDS_CLEANUP this is a singleton object
 225   PSAdaptiveSizePolicy(size_t init_eden_size,
 226                        size_t init_promo_size,
 227                        size_t init_survivor_size,
 228                        size_t space_alignment,
 229                        double gc_pause_goal_sec,
 230                        double gc_minor_pause_goal_sec,
 231                        uint gc_time_ratio);
 232 
 233   // Methods indicating events of interest to the adaptive size policy,
 234   // called by GC algorithms. It is the responsibility of users of this
 235   // policy to call these methods at the correct times!
 236   void major_collection_begin();
 237   void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);
 238 
 239   void tenured_allocation(size_t size) {
 240     _avg_pretenured->sample(size);
 241   }
 242 
 243   // Accessors
 244   // NEEDS_CLEANUP   should use sizes.hpp
 245 
 246   static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage);
 247 
 248   size_t calculated_old_free_size_in_bytes() const;
 249 
 250   size_t average_old_live_in_bytes() const {
 251     return (size_t) avg_old_live()->average();
 252   }
 253 
 254   size_t average_promoted_in_bytes() const {
 255     return (size_t)avg_promoted()->average();
 256   }
 257 
 258   size_t padded_average_promoted_in_bytes() const {
 259     return (size_t)avg_promoted()->padded_average();
 260   }
 261 
 262   int change_young_gen_for_maj_pauses() {
 263     return _change_young_gen_for_maj_pauses;
 264   }
 265   void set_change_young_gen_for_maj_pauses(int v) {
 266     _change_young_gen_for_maj_pauses = v;
 267   }
 268 
 269   int change_old_gen_for_min_pauses() {
 270     return _change_old_gen_for_min_pauses;
 271   }
 272   void set_change_old_gen_for_min_pauses(int v) {
 273     _change_old_gen_for_min_pauses = v;
 274   }
 275 
 276   // Return true if the old generation size was changed
 277   // to try to reach a pause time goal.
 278   bool old_gen_changed_for_pauses() {
 279     bool result = _change_old_gen_for_maj_pauses != 0 ||
 280                   _change_old_gen_for_min_pauses != 0;
 281     return result;
 282   }
 283 
 284   // Return true if the young generation size was changed
 285   // to try to reach a pause time goal.
 286   bool young_gen_changed_for_pauses() {
 287     bool result = _change_young_gen_for_min_pauses != 0 ||
 288                   _change_young_gen_for_maj_pauses != 0;
 289     return result;
 290   }
 291   // end flags for pause goal
 292 
 293   // Return true if the old generation size was changed
 294   // to try to reach a throughput goal.
 295   bool old_gen_changed_for_throughput() {
 296     bool result = _change_old_gen_for_throughput != 0;
 297     return result;
 298   }
 299 
 300   // Return true if the young generation size was changed
 301   // to try to reach a throughput goal.
 302   bool young_gen_changed_for_throughput() {
 303     bool result = _change_young_gen_for_throughput != 0;
 304     return result;
 305   }
 306 
 307   int decrease_for_footprint() { return _decrease_for_footprint; }
 308 
 309 
 310   // Accessors for estimators.  The slope of the linear fit is
 311   // currently all that is used for making decisions.
 312 
 313   LinearLeastSquareFit* major_pause_old_estimator() {
 314     return _major_pause_old_estimator;
 315   }
 316 
 317   LinearLeastSquareFit* major_pause_young_estimator() {
 318     return _major_pause_young_estimator;
 319   }
 320 
 321 
 322   virtual void clear_generation_free_space_flags();
 323 
 324   float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }
 325   float major_pause_young_slope() {
 326     return _major_pause_young_estimator->slope();
 327   }
 328   float major_collection_slope() { return _major_collection_estimator->slope();}
 329 
 330   bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }
 331 
 332   // Given the amount of live data in the heap, should we
 333   // perform a Full GC?
 334   bool should_full_GC(size_t live_in_old_gen);
 335 
 336   // Calculates optimal (free) space sizes for both the young and old
 337   // generations.  Stores results in _eden_size and _promo_size.
 338   // Takes current used space in all generations as input, as well
 339   // as an indication if a full gc has just been performed, for use
 340   // in deciding if an OOM error should be thrown.
 341   void compute_generations_free_space(size_t young_live,
 342                                       size_t eden_live,
 343                                       size_t old_live,
 344                                       size_t cur_eden,  // current eden in bytes
 345                                       size_t max_old_gen_size,
 346                                       size_t max_eden_size,
 347                                       bool   is_full_gc);
 348 
 349   void compute_eden_space_size(size_t young_live,
 350                                size_t eden_live,
 351                                size_t cur_eden,  // current eden in bytes
 352                                size_t max_eden_size,
 353                                bool   is_full_gc);
 354 
 355   void compute_old_gen_free_space(size_t old_live,
 356                                              size_t cur_eden,  // current eden in bytes
 357                                              size_t max_old_gen_size,
 358                                              bool   is_full_gc);
 359 
 360   // Calculates new survivor space size;  returns a new tenuring threshold
 361   // value. Stores new survivor size in _survivor_size.
 362   uint compute_survivor_space_size_and_threshold(bool   is_survivor_overflow,
 363                                                  uint    tenuring_threshold,
 364                                                  size_t survivor_limit);
 365 
 366   // Return the maximum size of a survivor space if the young generation were of
 367   // size gen_size.
 368   size_t max_survivor_size(size_t gen_size) {
 369     // Never allow the target survivor size to grow more than MinSurvivorRatio
 370     // of the young generation size.  We cannot grow into a two semi-space
 371     // system, with Eden zero sized.  Even if the survivor space grows, from()
 372     // might grow by moving the bottom boundary "down" -- so from space will
 373     // remain almost full anyway (top() will be near end(), but there will be a
 374     // large filler object at the bottom).
 375     const size_t sz = gen_size / MinSurvivorRatio;
 376     const size_t alignment = _space_alignment;
 377     return sz > alignment ? align_down(sz, alignment) : alignment;
 378   }
 379 
 380   size_t live_at_last_full_gc() {
 381     return _live_at_last_full_gc;
 382   }
 383 
 384   size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }
 385   void   reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }
 386 
 387   void set_bytes_absorbed_from_eden(size_t val) {
 388     _bytes_absorbed_from_eden = val;
 389   }
 390 
 391   // Update averages that are always used (even
 392   // if adaptive sizing is turned off).
 393   void update_averages(bool is_survivor_overflow,
 394                        size_t survived,
 395                        size_t promoted);
 396 
 397   // Printing support
 398   virtual bool print() const;
 399 
 400   // Decay the supplemental growth additive.
 401   void decay_supplemental_growth(bool is_full_gc);
 402 };
 403 
 404 #endif // SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP
--- EOF ---