1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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_G1_G1COLLECTORPOLICY_HPP
  26 #define SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
  27 
  28 #include "gc/g1/collectionSetChooser.hpp"
  29 #include "gc/g1/g1CollectorState.hpp"
  30 #include "gc/g1/g1GCPhaseTimes.hpp"
  31 #include "gc/g1/g1InCSetState.hpp"
  32 #include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"
  33 #include "gc/g1/g1MMUTracker.hpp"
  34 #include "gc/g1/g1Predictions.hpp"
  35 #include "gc/shared/collectorPolicy.hpp"
  36 #include "utilities/pair.hpp"
  37 
  38 // A G1CollectorPolicy makes policy decisions that determine the
  39 // characteristics of the collector.  Examples include:
  40 //   * choice of collection set.
  41 //   * when to collect.
  42 
  43 class HeapRegion;
  44 class CollectionSetChooser;
  45 class G1IHOPControl;
  46 
  47 // There are three command line options related to the young gen size:
  48 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
  49 // just a short form for NewSize==MaxNewSize). G1 will use its internal
  50 // heuristics to calculate the actual young gen size, so these options
  51 // basically only limit the range within which G1 can pick a young gen
  52 // size. Also, these are general options taking byte sizes. G1 will
  53 // internally work with a number of regions instead. So, some rounding
  54 // will occur.
  55 //
  56 // If nothing related to the the young gen size is set on the command
  57 // line we should allow the young gen to be between G1NewSizePercent
  58 // and G1MaxNewSizePercent of the heap size. This means that every time
  59 // the heap size changes, the limits for the young gen size will be
  60 // recalculated.
  61 //
  62 // If only -XX:NewSize is set we should use the specified value as the
  63 // minimum size for young gen. Still using G1MaxNewSizePercent of the
  64 // heap as maximum.
  65 //
  66 // If only -XX:MaxNewSize is set we should use the specified value as the
  67 // maximum size for young gen. Still using G1NewSizePercent of the heap
  68 // as minimum.
  69 //
  70 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
  71 // No updates when the heap size changes. There is a special case when
  72 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
  73 // different heuristic for calculating the collection set when we do mixed
  74 // collection.
  75 //
  76 // If only -XX:NewRatio is set we should use the specified ratio of the heap
  77 // as both min and max. This will be interpreted as "fixed" just like the
  78 // NewSize==MaxNewSize case above. But we will update the min and max
  79 // every time the heap size changes.
  80 //
  81 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
  82 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
  83 class G1YoungGenSizer : public CHeapObj<mtGC> {
  84 private:
  85   enum SizerKind {
  86     SizerDefaults,
  87     SizerNewSizeOnly,
  88     SizerMaxNewSizeOnly,
  89     SizerMaxAndNewSize,
  90     SizerNewRatio
  91   };
  92   SizerKind _sizer_kind;
  93   uint _min_desired_young_length;
  94   uint _max_desired_young_length;
  95   bool _adaptive_size;
  96   uint calculate_default_min_length(uint new_number_of_heap_regions);
  97   uint calculate_default_max_length(uint new_number_of_heap_regions);
  98 
  99   // Update the given values for minimum and maximum young gen length in regions
 100   // given the number of heap regions depending on the kind of sizing algorithm.
 101   void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
 102 
 103 public:
 104   G1YoungGenSizer();
 105   // Calculate the maximum length of the young gen given the number of regions
 106   // depending on the sizing algorithm.
 107   uint max_young_length(uint number_of_heap_regions);
 108 
 109   void heap_size_changed(uint new_number_of_heap_regions);
 110   uint min_desired_young_length() {
 111     return _min_desired_young_length;
 112   }
 113   uint max_desired_young_length() {
 114     return _max_desired_young_length;
 115   }
 116 
 117   bool adaptive_young_list_length() const {
 118     return _adaptive_size;
 119   }
 120 };
 121 
 122 class G1CollectorPolicy: public CollectorPolicy {
 123  private:
 124   G1IHOPControl* _ihop_control;
 125 
 126   G1IHOPControl* create_ihop_control() const;
 127   // Update the IHOP control with necessary statistics.
 128   void update_ihop_prediction(double mutator_time_s,
 129                               size_t mutator_alloc_bytes,
 130                               size_t young_gen_size);
 131   void report_ihop_statistics();
 132 
 133   G1Predictions _predictor;
 134 
 135   double get_new_prediction(TruncatedSeq const* seq) const;
 136   size_t get_new_size_prediction(TruncatedSeq const* seq) const;
 137 
 138   G1MMUTracker* _mmu_tracker;
 139 
 140   void initialize_alignments();
 141   void initialize_flags();
 142 
 143   CollectionSetChooser* _cset_chooser;
 144 
 145   double _full_collection_start_sec;
 146 
 147   // These exclude marking times.
 148   TruncatedSeq* _recent_gc_times_ms;
 149 
 150   TruncatedSeq* _concurrent_mark_remark_times_ms;
 151   TruncatedSeq* _concurrent_mark_cleanup_times_ms;
 152 
 153   // Ratio check data for determining if heap growth is necessary.
 154   uint _ratio_over_threshold_count;
 155   double _ratio_over_threshold_sum;
 156   uint _pauses_since_start;
 157 
 158   uint _young_list_target_length;
 159   uint _young_list_fixed_length;
 160 
 161   // The max number of regions we can extend the eden by while the GC
 162   // locker is active. This should be >= _young_list_target_length;
 163   uint _young_list_max_length;
 164 
 165   SurvRateGroup* _short_lived_surv_rate_group;
 166   SurvRateGroup* _survivor_surv_rate_group;
 167   // add here any more surv rate groups
 168 
 169   double _gc_overhead_perc;
 170 
 171   double _reserve_factor;
 172   uint   _reserve_regions;
 173 
 174   enum PredictionConstants {
 175     TruncatedSeqLength = 10,
 176     NumPrevPausesForHeuristics = 10,
 177     // MinOverThresholdForGrowth must be less than NumPrevPausesForHeuristics,
 178     // representing the minimum number of pause time ratios that exceed
 179     // GCTimeRatio before a heap expansion will be triggered.
 180     MinOverThresholdForGrowth = 4
 181   };
 182 
 183   TruncatedSeq* _alloc_rate_ms_seq;
 184   double        _prev_collection_pause_end_ms;
 185 
 186   TruncatedSeq* _rs_length_diff_seq;
 187   TruncatedSeq* _cost_per_card_ms_seq;
 188   TruncatedSeq* _cost_scan_hcc_seq;
 189   TruncatedSeq* _young_cards_per_entry_ratio_seq;
 190   TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
 191   TruncatedSeq* _cost_per_entry_ms_seq;
 192   TruncatedSeq* _mixed_cost_per_entry_ms_seq;
 193   TruncatedSeq* _cost_per_byte_ms_seq;
 194   TruncatedSeq* _constant_other_time_ms_seq;
 195   TruncatedSeq* _young_other_cost_per_region_ms_seq;
 196   TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
 197 
 198   TruncatedSeq* _pending_cards_seq;
 199   TruncatedSeq* _rs_lengths_seq;
 200 
 201   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
 202 
 203   G1YoungGenSizer* _young_gen_sizer;
 204 
 205   uint _eden_cset_region_length;
 206   uint _survivor_cset_region_length;
 207   uint _old_cset_region_length;
 208 
 209   void init_cset_region_lengths(uint eden_cset_region_length,
 210                                 uint survivor_cset_region_length);
 211 
 212   uint eden_cset_region_length() const     { return _eden_cset_region_length;     }
 213   uint survivor_cset_region_length() const { return _survivor_cset_region_length; }
 214   uint old_cset_region_length() const      { return _old_cset_region_length;      }
 215 
 216   uint _free_regions_at_end_of_collection;
 217 
 218   size_t _recorded_rs_lengths;
 219   size_t _max_rs_lengths;
 220 
 221   size_t _rs_lengths_prediction;
 222 
 223 #ifndef PRODUCT
 224   bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
 225 #endif // PRODUCT
 226 
 227   void adjust_concurrent_refinement(double update_rs_time,
 228                                     double update_rs_processed_buffers,
 229                                     double goal_ms);
 230 
 231   double _pause_time_target_ms;
 232 
 233   size_t _pending_cards;
 234 
 235   // The amount of allocated bytes in old gen during the last mutator and the following
 236   // young GC phase.
 237   size_t _bytes_allocated_in_old_since_last_gc;
 238 
 239   G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;
 240 public:
 241   const G1Predictions& predictor() const { return _predictor; }
 242 
 243   // Add the given number of bytes to the total number of allocated bytes in the old gen.
 244   void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }
 245 
 246   // Accessors
 247 
 248   void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
 249     hr->set_eden();
 250     hr->install_surv_rate_group(_short_lived_surv_rate_group);
 251     hr->set_young_index_in_cset(young_index_in_cset);
 252   }
 253 
 254   void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
 255     assert(hr->is_survivor(), "pre-condition");
 256     hr->install_surv_rate_group(_survivor_surv_rate_group);
 257     hr->set_young_index_in_cset(young_index_in_cset);
 258   }
 259 
 260 #ifndef PRODUCT
 261   bool verify_young_ages();
 262 #endif // PRODUCT
 263 
 264   void record_max_rs_lengths(size_t rs_lengths) {
 265     _max_rs_lengths = rs_lengths;
 266   }
 267 
 268   size_t predict_rs_length_diff() const;
 269 
 270   double predict_alloc_rate_ms() const;
 271 
 272   double predict_cost_per_card_ms() const;
 273 
 274   double predict_scan_hcc_ms() const;
 275 
 276   double predict_rs_update_time_ms(size_t pending_cards) const;
 277 
 278   double predict_young_cards_per_entry_ratio() const;
 279 
 280   double predict_mixed_cards_per_entry_ratio() const;
 281 
 282   size_t predict_young_card_num(size_t rs_length) const;
 283 
 284   size_t predict_non_young_card_num(size_t rs_length) const;
 285 
 286   double predict_rs_scan_time_ms(size_t card_num) const;
 287 
 288   double predict_mixed_rs_scan_time_ms(size_t card_num) const;
 289 
 290   double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const;
 291 
 292   double predict_object_copy_time_ms(size_t bytes_to_copy) const;
 293 
 294   double predict_constant_other_time_ms() const;
 295 
 296   double predict_young_other_time_ms(size_t young_num) const;
 297 
 298   double predict_non_young_other_time_ms(size_t non_young_num) const;
 299 
 300   double predict_base_elapsed_time_ms(size_t pending_cards) const;
 301   double predict_base_elapsed_time_ms(size_t pending_cards,
 302                                       size_t scanned_cards) const;
 303   size_t predict_bytes_to_copy(HeapRegion* hr) const;
 304   double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc) const;
 305 
 306   void set_recorded_rs_lengths(size_t rs_lengths);
 307 
 308   uint cset_region_length() const       { return young_cset_region_length() +
 309                                            old_cset_region_length(); }
 310   uint young_cset_region_length() const { return eden_cset_region_length() +
 311                                            survivor_cset_region_length(); }
 312 
 313   double predict_survivor_regions_evac_time() const;
 314 
 315   bool should_update_surv_rate_group_predictors() {
 316     return collector_state()->last_gc_was_young() && !collector_state()->in_marking_window();
 317   }
 318 
 319   void cset_regions_freed() {
 320     bool update = should_update_surv_rate_group_predictors();
 321 
 322     _short_lived_surv_rate_group->all_surviving_words_recorded(update);
 323     _survivor_surv_rate_group->all_surviving_words_recorded(update);
 324   }
 325 
 326   G1MMUTracker* mmu_tracker() {
 327     return _mmu_tracker;
 328   }
 329 
 330   const G1MMUTracker* mmu_tracker() const {
 331     return _mmu_tracker;
 332   }
 333 
 334   double max_pause_time_ms() const {
 335     return _mmu_tracker->max_gc_time() * 1000.0;
 336   }
 337 
 338   double predict_remark_time_ms() const;
 339 
 340   double predict_cleanup_time_ms() const;
 341 
 342   // Returns an estimate of the survival rate of the region at yg-age
 343   // "yg_age".
 344   double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const;
 345 
 346   double predict_yg_surv_rate(int age) const;
 347 
 348   double accum_yg_surv_rate_pred(int age) const;
 349 
 350 protected:
 351   virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;
 352   virtual double other_time_ms(double pause_time_ms) const;
 353 
 354   double young_other_time_ms() const;
 355   double non_young_other_time_ms() const;
 356   double constant_other_time_ms(double pause_time_ms) const;
 357 
 358   CollectionSetChooser* cset_chooser() const {
 359     return _cset_chooser;
 360   }
 361 
 362 private:
 363   // Statistics kept per GC stoppage, pause or full.
 364   TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
 365 
 366   // Add a new GC of the given duration and end time to the record.
 367   void update_recent_gc_times(double end_time_sec, double elapsed_ms);
 368 
 369   // The head of the list (via "next_in_collection_set()") representing the
 370   // current collection set. Set from the incrementally built collection
 371   // set at the start of the pause.
 372   HeapRegion* _collection_set;
 373 
 374   // The number of bytes in the collection set before the pause. Set from
 375   // the incrementally built collection set at the start of an evacuation
 376   // pause, and incremented in finalize_old_cset_part() when adding old regions
 377   // (if any) to the collection set.
 378   size_t _collection_set_bytes_used_before;
 379 
 380   // The number of bytes copied during the GC.
 381   size_t _bytes_copied_during_gc;
 382 
 383   // The associated information that is maintained while the incremental
 384   // collection set is being built with young regions. Used to populate
 385   // the recorded info for the evacuation pause.
 386 
 387   enum CSetBuildType {
 388     Active,             // We are actively building the collection set
 389     Inactive            // We are not actively building the collection set
 390   };
 391 
 392   CSetBuildType _inc_cset_build_state;
 393 
 394   // The head of the incrementally built collection set.
 395   HeapRegion* _inc_cset_head;
 396 
 397   // The tail of the incrementally built collection set.
 398   HeapRegion* _inc_cset_tail;
 399 
 400   // The number of bytes in the incrementally built collection set.
 401   // Used to set _collection_set_bytes_used_before at the start of
 402   // an evacuation pause.
 403   size_t _inc_cset_bytes_used_before;
 404 
 405   // Used to record the highest end of heap region in collection set
 406   HeapWord* _inc_cset_max_finger;
 407 
 408   // The RSet lengths recorded for regions in the CSet. It is updated
 409   // by the thread that adds a new region to the CSet. We assume that
 410   // only one thread can be allocating a new CSet region (currently,
 411   // it does so after taking the Heap_lock) hence no need to
 412   // synchronize updates to this field.
 413   size_t _inc_cset_recorded_rs_lengths;
 414 
 415   // A concurrent refinement thread periodically samples the young
 416   // region RSets and needs to update _inc_cset_recorded_rs_lengths as
 417   // the RSets grow. Instead of having to synchronize updates to that
 418   // field we accumulate them in this field and add it to
 419   // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
 420   ssize_t _inc_cset_recorded_rs_lengths_diffs;
 421 
 422   // The predicted elapsed time it will take to collect the regions in
 423   // the CSet. This is updated by the thread that adds a new region to
 424   // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
 425   // MT-safety assumptions.
 426   double _inc_cset_predicted_elapsed_time_ms;
 427 
 428   // See the comment for _inc_cset_recorded_rs_lengths_diffs.
 429   double _inc_cset_predicted_elapsed_time_ms_diffs;
 430 
 431   // Stash a pointer to the g1 heap.
 432   G1CollectedHeap* _g1;
 433 
 434   G1GCPhaseTimes* _phase_times;
 435 
 436   // The ratio of gc time to elapsed time, computed over recent pauses,
 437   // and the ratio for just the last pause.
 438   double _recent_avg_pause_time_ratio;
 439   double _last_pause_time_ratio;
 440 
 441   double recent_avg_pause_time_ratio() const {
 442     return _recent_avg_pause_time_ratio;
 443   }
 444 
 445   // This set of variables tracks the collector efficiency, in order to
 446   // determine whether we should initiate a new marking.
 447   double _mark_remark_start_sec;
 448   double _mark_cleanup_start_sec;
 449 
 450   // Updates the internal young list maximum and target lengths. Returns the
 451   // unbounded young list target length.
 452   uint update_young_list_max_and_target_length();
 453   uint update_young_list_max_and_target_length(size_t rs_lengths);
 454 
 455   // Update the young list target length either by setting it to the
 456   // desired fixed value or by calculating it using G1's pause
 457   // prediction model. If no rs_lengths parameter is passed, predict
 458   // the RS lengths using the prediction model, otherwise use the
 459   // given rs_lengths as the prediction.
 460   // Returns the unbounded young list target length.
 461   uint update_young_list_target_length(size_t rs_lengths);
 462 
 463   // Calculate and return the minimum desired young list target
 464   // length. This is the minimum desired young list length according
 465   // to the user's inputs.
 466   uint calculate_young_list_desired_min_length(uint base_min_length) const;
 467 
 468   // Calculate and return the maximum desired young list target
 469   // length. This is the maximum desired young list length according
 470   // to the user's inputs.
 471   uint calculate_young_list_desired_max_length() const;
 472 
 473   // Calculate and return the maximum young list target length that
 474   // can fit into the pause time goal. The parameters are: rs_lengths
 475   // represent the prediction of how large the young RSet lengths will
 476   // be, base_min_length is the already existing number of regions in
 477   // the young list, min_length and max_length are the desired min and
 478   // max young list length according to the user's inputs.
 479   uint calculate_young_list_target_length(size_t rs_lengths,
 480                                           uint base_min_length,
 481                                           uint desired_min_length,
 482                                           uint desired_max_length) const;
 483 
 484   // Result of the bounded_young_list_target_length() method, containing both the
 485   // bounded as well as the unbounded young list target lengths in this order.
 486   typedef Pair<uint, uint, StackObj> YoungTargetLengths;
 487   YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;
 488 
 489   void update_rs_lengths_prediction();
 490   void update_rs_lengths_prediction(size_t prediction);
 491 
 492   // Calculate and return chunk size (in number of regions) for parallel
 493   // concurrent mark cleanup.
 494   uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const;
 495 
 496   // Check whether a given young length (young_length) fits into the
 497   // given target pause time and whether the prediction for the amount
 498   // of objects to be copied for the given length will fit into the
 499   // given free space (expressed by base_free_regions).  It is used by
 500   // calculate_young_list_target_length().
 501   bool predict_will_fit(uint young_length, double base_time_ms,
 502                         uint base_free_regions, double target_pause_time_ms) const;
 503 
 504   // Calculate the minimum number of old regions we'll add to the CSet
 505   // during a mixed GC.
 506   uint calc_min_old_cset_length() const;
 507 
 508   // Calculate the maximum number of old regions we'll add to the CSet
 509   // during a mixed GC.
 510   uint calc_max_old_cset_length() const;
 511 
 512   // Returns the given amount of uncollected reclaimable space
 513   // as a percentage of the current heap capacity.
 514   double reclaimable_bytes_perc(size_t reclaimable_bytes) const;
 515 
 516   // Sets up marking if proper conditions are met.
 517   void maybe_start_marking();
 518 
 519   // The kind of STW pause.
 520   enum PauseKind {
 521     FullGC,
 522     YoungOnlyGC,
 523     MixedGC,
 524     LastYoungGC,
 525     InitialMarkGC,
 526     Cleanup,
 527     Remark
 528   };
 529 
 530   // Calculate PauseKind from internal state.
 531   PauseKind young_gc_pause_kind() const;
 532   // Record the given STW pause with the given start and end times (in s).
 533   void record_pause(PauseKind kind, double start, double end);
 534   // Indicate that we aborted marking before doing any mixed GCs.
 535   void abort_time_to_mixed_tracking();
 536 public:
 537 
 538   G1CollectorPolicy();
 539 
 540   virtual ~G1CollectorPolicy();
 541 
 542   virtual G1CollectorPolicy* as_g1_policy() { return this; }
 543 
 544   G1CollectorState* collector_state() const;
 545 
 546   G1GCPhaseTimes* phase_times() const { return _phase_times; }
 547 
 548   // Check the current value of the young list RSet lengths and
 549   // compare it against the last prediction. If the current value is
 550   // higher, recalculate the young list target length prediction.
 551   void revise_young_list_target_length_if_necessary();
 552 
 553   // This should be called after the heap is resized.
 554   void record_new_heap_size(uint new_number_of_regions);
 555 
 556   void init();
 557 
 558   virtual void note_gc_start(uint num_active_workers);
 559 
 560   // Create jstat counters for the policy.
 561   virtual void initialize_gc_policy_counters();
 562 
 563   virtual HeapWord* mem_allocate_work(size_t size,
 564                                       bool is_tlab,
 565                                       bool* gc_overhead_limit_was_exceeded);
 566 
 567   // This method controls how a collector handles one or more
 568   // of its generations being fully allocated.
 569   virtual HeapWord* satisfy_failed_allocation(size_t size,
 570                                               bool is_tlab);
 571 
 572   bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
 573 
 574   bool about_to_start_mixed_phase() const;
 575 
 576   // Record the start and end of an evacuation pause.
 577   void record_collection_pause_start(double start_time_sec);
 578   void record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc);
 579 
 580   // Record the start and end of a full collection.
 581   void record_full_collection_start();
 582   void record_full_collection_end();
 583 
 584   // Must currently be called while the world is stopped.
 585   void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
 586 
 587   // Record start and end of remark.
 588   void record_concurrent_mark_remark_start();
 589   void record_concurrent_mark_remark_end();
 590 
 591   // Record start, end, and completion of cleanup.
 592   void record_concurrent_mark_cleanup_start();
 593   void record_concurrent_mark_cleanup_end();
 594   void record_concurrent_mark_cleanup_completed();
 595 
 596   virtual void print_phases();
 597 
 598   // Record how much space we copied during a GC. This is typically
 599   // called when a GC alloc region is being retired.
 600   void record_bytes_copied_during_gc(size_t bytes) {
 601     _bytes_copied_during_gc += bytes;
 602   }
 603 
 604   // The amount of space we copied during a GC.
 605   size_t bytes_copied_during_gc() const {
 606     return _bytes_copied_during_gc;
 607   }
 608 
 609   size_t collection_set_bytes_used_before() const {
 610     return _collection_set_bytes_used_before;
 611   }
 612 
 613   // Determine whether there are candidate regions so that the
 614   // next GC should be mixed. The two action strings are used
 615   // in the ergo output when the method returns true or false.
 616   bool next_gc_should_be_mixed(const char* true_action_str,
 617                                const char* false_action_str) const;
 618 
 619   // Choose a new collection set.  Marks the chosen regions as being
 620   // "in_collection_set", and links them together.  The head and number of
 621   // the collection set are available via access methods.
 622   double finalize_young_cset_part(double target_pause_time_ms);
 623   virtual void finalize_old_cset_part(double time_remaining_ms);
 624 
 625   // The head of the list (via "next_in_collection_set()") representing the
 626   // current collection set.
 627   HeapRegion* collection_set() { return _collection_set; }
 628 
 629   void clear_collection_set() { _collection_set = NULL; }
 630 
 631   // Add old region "hr" to the CSet.
 632   void add_old_region_to_cset(HeapRegion* hr);
 633 
 634   // Incremental CSet Support
 635 
 636   // The head of the incrementally built collection set.
 637   HeapRegion* inc_cset_head() { return _inc_cset_head; }
 638 
 639   // The tail of the incrementally built collection set.
 640   HeapRegion* inc_set_tail() { return _inc_cset_tail; }
 641 
 642   // Initialize incremental collection set info.
 643   void start_incremental_cset_building();
 644 
 645   // Perform any final calculations on the incremental CSet fields
 646   // before we can use them.
 647   void finalize_incremental_cset_building();
 648 
 649   void clear_incremental_cset() {
 650     _inc_cset_head = NULL;
 651     _inc_cset_tail = NULL;
 652   }
 653 
 654   // Stop adding regions to the incremental collection set
 655   void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
 656 
 657   // Add information about hr to the aggregated information for the
 658   // incrementally built collection set.
 659   void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
 660 
 661   // Update information about hr in the aggregated information for
 662   // the incrementally built collection set.
 663   void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
 664 
 665 private:
 666   // Update the incremental cset information when adding a region
 667   // (should not be called directly).
 668   void add_region_to_incremental_cset_common(HeapRegion* hr);
 669 
 670   // Set the state to start a concurrent marking cycle and clear
 671   // _initiate_conc_mark_if_possible because it has now been
 672   // acted on.
 673   void initiate_conc_mark();
 674 
 675 public:
 676   // Add hr to the LHS of the incremental collection set.
 677   void add_region_to_incremental_cset_lhs(HeapRegion* hr);
 678 
 679   // Add hr to the RHS of the incremental collection set.
 680   void add_region_to_incremental_cset_rhs(HeapRegion* hr);
 681 
 682 #ifndef PRODUCT
 683   void print_collection_set(HeapRegion* list_head, outputStream* st);
 684 #endif // !PRODUCT
 685 
 686   // This sets the initiate_conc_mark_if_possible() flag to start a
 687   // new cycle, as long as we are not already in one. It's best if it
 688   // is called during a safepoint when the test whether a cycle is in
 689   // progress or not is stable.
 690   bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
 691 
 692   // This is called at the very beginning of an evacuation pause (it
 693   // has to be the first thing that the pause does). If
 694   // initiate_conc_mark_if_possible() is true, and the concurrent
 695   // marking thread has completed its work during the previous cycle,
 696   // it will set during_initial_mark_pause() to so that the pause does
 697   // the initial-mark work and start a marking cycle.
 698   void decide_on_conc_mark_initiation();
 699 
 700   // If an expansion would be appropriate, because recent GC overhead had
 701   // exceeded the desired limit, return an amount to expand by.
 702   virtual size_t expansion_amount();
 703 
 704   // Clear ratio tracking data used by expansion_amount().
 705   void clear_ratio_check_data();
 706 
 707   // Print stats on young survival ratio
 708   void print_yg_surv_rate_info() const;
 709 
 710   void finished_recalculating_age_indexes(bool is_survivors) {
 711     if (is_survivors) {
 712       _survivor_surv_rate_group->finished_recalculating_age_indexes();
 713     } else {
 714       _short_lived_surv_rate_group->finished_recalculating_age_indexes();
 715     }
 716     // do that for any other surv rate groups
 717   }
 718 
 719   size_t young_list_target_length() const { return _young_list_target_length; }
 720 
 721   bool is_young_list_full() const;
 722 
 723   bool can_expand_young_list() const;
 724 
 725   uint young_list_max_length() const {
 726     return _young_list_max_length;
 727   }
 728 
 729   bool adaptive_young_list_length() const {
 730     return _young_gen_sizer->adaptive_young_list_length();
 731   }
 732 
 733   virtual bool should_process_references() const {
 734     return true;
 735   }
 736 
 737 private:
 738   //
 739   // Survivor regions policy.
 740   //
 741 
 742   // Current tenuring threshold, set to 0 if the collector reaches the
 743   // maximum amount of survivors regions.
 744   uint _tenuring_threshold;
 745 
 746   // The limit on the number of regions allocated for survivors.
 747   uint _max_survivor_regions;
 748 
 749   // For reporting purposes.
 750   // The value of _heap_bytes_before_gc is also used to calculate
 751   // the cost of copying.
 752 
 753   // The amount of survivor regions after a collection.
 754   uint _recorded_survivor_regions;
 755   // List of survivor regions.
 756   HeapRegion* _recorded_survivor_head;
 757   HeapRegion* _recorded_survivor_tail;
 758 
 759   AgeTable _survivors_age_table;
 760 
 761 public:
 762   uint tenuring_threshold() const { return _tenuring_threshold; }
 763 
 764   uint max_survivor_regions() {
 765     return _max_survivor_regions;
 766   }
 767 
 768   static const uint REGIONS_UNLIMITED = (uint) -1;
 769 
 770   uint max_regions(InCSetState dest) const {
 771     switch (dest.value()) {
 772       case InCSetState::Young:
 773         return _max_survivor_regions;
 774       case InCSetState::Old:
 775         return REGIONS_UNLIMITED;
 776       default:
 777         assert(false, "Unknown dest state: " CSETSTATE_FORMAT, dest.value());
 778         break;
 779     }
 780     // keep some compilers happy
 781     return 0;
 782   }
 783 
 784   void note_start_adding_survivor_regions() {
 785     _survivor_surv_rate_group->start_adding_regions();
 786   }
 787 
 788   void note_stop_adding_survivor_regions() {
 789     _survivor_surv_rate_group->stop_adding_regions();
 790   }
 791 
 792   void record_survivor_regions(uint regions,
 793                                HeapRegion* head,
 794                                HeapRegion* tail) {
 795     _recorded_survivor_regions = regions;
 796     _recorded_survivor_head    = head;
 797     _recorded_survivor_tail    = tail;
 798   }
 799 
 800   uint recorded_survivor_regions() const {
 801     return _recorded_survivor_regions;
 802   }
 803 
 804   void record_age_table(AgeTable* age_table) {
 805     _survivors_age_table.merge(age_table);
 806   }
 807 
 808   void update_max_gc_locker_expansion();
 809 
 810   // Calculates survivor space parameters.
 811   void update_survivors_policy();
 812 
 813   virtual void post_heap_initialize();
 814 };
 815 
 816 #endif // SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
--- EOF ---