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 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses
  48 // (the latter may contain non-young regions - i.e. regions that are
  49 // technically in old) while TraceOldGenTime collects data about full GCs.
  50 class TraceYoungGenTimeData : public CHeapObj<mtGC> {
  51  private:
  52   unsigned  _young_pause_num;
  53   unsigned  _mixed_pause_num;
  54 
  55   NumberSeq _all_stop_world_times_ms;
  56   NumberSeq _all_yield_times_ms;
  57 
  58   NumberSeq _total;
  59   NumberSeq _other;
  60   NumberSeq _root_region_scan_wait;
  61   NumberSeq _parallel;
  62   NumberSeq _ext_root_scan;
  63   NumberSeq _satb_filtering;
  64   NumberSeq _update_rs;
  65   NumberSeq _scan_rs;
  66   NumberSeq _obj_copy;
  67   NumberSeq _termination;
  68   NumberSeq _parallel_other;
  69   NumberSeq _clear_ct;
  70 
  71   void print_summary(const char* str, const NumberSeq* seq) const;
  72   void print_summary_sd(const char* str, const NumberSeq* seq) const;
  73 
  74 public:
  75    TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
  76   void record_start_collection(double time_to_stop_the_world_ms);
  77   void record_yield_time(double yield_time_ms);
  78   void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
  79   void increment_young_collection_count();
  80   void increment_mixed_collection_count();
  81   void print() const;
  82 };
  83 
  84 class TraceOldGenTimeData : public CHeapObj<mtGC> {
  85  private:
  86   NumberSeq _all_full_gc_times;
  87 
  88  public:
  89   void record_full_collection(double full_gc_time_ms);
  90   void print() const;
  91 };
  92 
  93 // There are three command line options related to the young gen size:
  94 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
  95 // just a short form for NewSize==MaxNewSize). G1 will use its internal
  96 // heuristics to calculate the actual young gen size, so these options
  97 // basically only limit the range within which G1 can pick a young gen
  98 // size. Also, these are general options taking byte sizes. G1 will
  99 // internally work with a number of regions instead. So, some rounding
 100 // will occur.
 101 //
 102 // If nothing related to the the young gen size is set on the command
 103 // line we should allow the young gen to be between G1NewSizePercent
 104 // and G1MaxNewSizePercent of the heap size. This means that every time
 105 // the heap size changes, the limits for the young gen size will be
 106 // recalculated.
 107 //
 108 // If only -XX:NewSize is set we should use the specified value as the
 109 // minimum size for young gen. Still using G1MaxNewSizePercent of the
 110 // heap as maximum.
 111 //
 112 // If only -XX:MaxNewSize is set we should use the specified value as the
 113 // maximum size for young gen. Still using G1NewSizePercent of the heap
 114 // as minimum.
 115 //
 116 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
 117 // No updates when the heap size changes. There is a special case when
 118 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
 119 // different heuristic for calculating the collection set when we do mixed
 120 // collection.
 121 //
 122 // If only -XX:NewRatio is set we should use the specified ratio of the heap
 123 // as both min and max. This will be interpreted as "fixed" just like the
 124 // NewSize==MaxNewSize case above. But we will update the min and max
 125 // every time the heap size changes.
 126 //
 127 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
 128 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
 129 class G1YoungGenSizer : public CHeapObj<mtGC> {
 130 private:
 131   enum SizerKind {
 132     SizerDefaults,
 133     SizerNewSizeOnly,
 134     SizerMaxNewSizeOnly,
 135     SizerMaxAndNewSize,
 136     SizerNewRatio
 137   };
 138   SizerKind _sizer_kind;
 139   uint _min_desired_young_length;
 140   uint _max_desired_young_length;
 141   bool _adaptive_size;
 142   uint calculate_default_min_length(uint new_number_of_heap_regions);
 143   uint calculate_default_max_length(uint new_number_of_heap_regions);
 144 
 145   // Update the given values for minimum and maximum young gen length in regions
 146   // given the number of heap regions depending on the kind of sizing algorithm.
 147   void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
 148 
 149 public:
 150   G1YoungGenSizer();
 151   // Calculate the maximum length of the young gen given the number of regions
 152   // depending on the sizing algorithm.
 153   uint max_young_length(uint number_of_heap_regions);
 154 
 155   void heap_size_changed(uint new_number_of_heap_regions);
 156   uint min_desired_young_length() {
 157     return _min_desired_young_length;
 158   }
 159   uint max_desired_young_length() {
 160     return _max_desired_young_length;
 161   }
 162   bool adaptive_young_list_length() const {
 163     return _adaptive_size;
 164   }
 165 };
 166 
 167 class G1CollectorPolicy: public CollectorPolicy {
 168  private:
 169   G1IHOPControl* _ihop_control;
 170 
 171   G1IHOPControl* create_ihop_control() const;
 172   // Update the IHOP control with necessary statistics.
 173   void update_ihop_prediction(double mutator_time_s,
 174                               size_t mutator_alloc_bytes,
 175                               size_t young_gen_size);
 176   void report_ihop_statistics();
 177 
 178   G1Predictions _predictor;
 179 
 180   double get_new_prediction(TruncatedSeq const* seq) const;
 181 
 182   // either equal to the number of parallel threads, if ParallelGCThreads
 183   // has been set, or 1 otherwise
 184   int _parallel_gc_threads;
 185 
 186   // The number of GC threads currently active.
 187   uintx _no_of_gc_threads;
 188 
 189   G1MMUTracker* _mmu_tracker;
 190 
 191   void initialize_alignments();
 192   void initialize_flags();
 193 
 194   CollectionSetChooser* _cset_chooser;
 195 
 196   double _full_collection_start_sec;
 197 
 198   // These exclude marking times.
 199   TruncatedSeq* _recent_gc_times_ms;
 200 
 201   TruncatedSeq* _concurrent_mark_remark_times_ms;
 202   TruncatedSeq* _concurrent_mark_cleanup_times_ms;
 203 
 204   TraceYoungGenTimeData _trace_young_gen_time_data;
 205   TraceOldGenTimeData   _trace_old_gen_time_data;
 206 
 207   double _stop_world_start;
 208 
 209   uint _young_list_target_length;
 210   uint _young_list_fixed_length;
 211 
 212   // The max number of regions we can extend the eden by while the GC
 213   // locker is active. This should be >= _young_list_target_length;
 214   uint _young_list_max_length;
 215 
 216   SurvRateGroup* _short_lived_surv_rate_group;
 217   SurvRateGroup* _survivor_surv_rate_group;
 218   // add here any more surv rate groups
 219 
 220   double _gc_overhead_perc;
 221 
 222   double _reserve_factor;
 223   uint   _reserve_regions;
 224 
 225   enum PredictionConstants {
 226     TruncatedSeqLength = 10,
 227     NumPrevPausesForHeuristics = 10
 228   };
 229 
 230   TruncatedSeq* _alloc_rate_ms_seq;
 231   double        _prev_collection_pause_end_ms;
 232 
 233   TruncatedSeq* _rs_length_diff_seq;
 234   TruncatedSeq* _cost_per_card_ms_seq;
 235   TruncatedSeq* _cost_scan_hcc_seq;
 236   TruncatedSeq* _young_cards_per_entry_ratio_seq;
 237   TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
 238   TruncatedSeq* _cost_per_entry_ms_seq;
 239   TruncatedSeq* _mixed_cost_per_entry_ms_seq;
 240   TruncatedSeq* _cost_per_byte_ms_seq;
 241   TruncatedSeq* _constant_other_time_ms_seq;
 242   TruncatedSeq* _young_other_cost_per_region_ms_seq;
 243   TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
 244 
 245   TruncatedSeq* _pending_cards_seq;
 246   TruncatedSeq* _rs_lengths_seq;
 247 
 248   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
 249 
 250   G1YoungGenSizer* _young_gen_sizer;
 251 
 252   uint _eden_cset_region_length;
 253   uint _survivor_cset_region_length;
 254   uint _old_cset_region_length;
 255 
 256   void init_cset_region_lengths(uint eden_cset_region_length,
 257                                 uint survivor_cset_region_length);
 258 
 259   uint eden_cset_region_length() const     { return _eden_cset_region_length;     }
 260   uint survivor_cset_region_length() const { return _survivor_cset_region_length; }
 261   uint old_cset_region_length() const      { return _old_cset_region_length;      }
 262 
 263   uint _free_regions_at_end_of_collection;
 264 
 265   size_t _recorded_rs_lengths;
 266   size_t _max_rs_lengths;
 267 
 268   size_t _rs_lengths_prediction;
 269 
 270 #ifndef PRODUCT
 271   bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
 272 #endif // PRODUCT
 273 
 274   void adjust_concurrent_refinement(double update_rs_time,
 275                                     double update_rs_processed_buffers,
 276                                     double goal_ms);
 277 
 278   uintx no_of_gc_threads() { return _no_of_gc_threads; }
 279   void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
 280 
 281   double _pause_time_target_ms;
 282 
 283   size_t _pending_cards;
 284 
 285   // The amount of allocated bytes in old gen during the last mutator and the following
 286   // young GC phase.
 287   size_t _bytes_allocated_in_old_since_last_gc;
 288 
 289   G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;
 290 public:
 291   const G1Predictions& predictor() const { return _predictor; }
 292 
 293   // Add the given number of bytes to the total number of allocated bytes in the old gen.
 294   void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }
 295 
 296   // Accessors
 297 
 298   void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
 299     hr->set_eden();
 300     hr->install_surv_rate_group(_short_lived_surv_rate_group);
 301     hr->set_young_index_in_cset(young_index_in_cset);
 302   }
 303 
 304   void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
 305     assert(hr->is_survivor(), "pre-condition");
 306     hr->install_surv_rate_group(_survivor_surv_rate_group);
 307     hr->set_young_index_in_cset(young_index_in_cset);
 308   }
 309 
 310 #ifndef PRODUCT
 311   bool verify_young_ages();
 312 #endif // PRODUCT
 313 
 314   void record_max_rs_lengths(size_t rs_lengths) {
 315     _max_rs_lengths = rs_lengths;
 316   }
 317 
 318   size_t predict_rs_length_diff() const;
 319 
 320   double predict_alloc_rate_ms() const;
 321 
 322   double predict_cost_per_card_ms() const;
 323 
 324   double predict_scan_hcc_ms() const;
 325 
 326   double predict_rs_update_time_ms(size_t pending_cards) const;
 327 
 328   double predict_young_cards_per_entry_ratio() const;
 329 
 330   double predict_mixed_cards_per_entry_ratio() const;
 331 
 332   size_t predict_young_card_num(size_t rs_length) const;
 333 
 334   size_t predict_non_young_card_num(size_t rs_length) const;
 335 
 336   double predict_rs_scan_time_ms(size_t card_num) const;
 337 
 338   double predict_mixed_rs_scan_time_ms(size_t card_num) const;
 339 
 340   double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const;
 341 
 342   double predict_object_copy_time_ms(size_t bytes_to_copy) const;
 343 
 344   double predict_constant_other_time_ms() const;
 345 
 346   double predict_young_other_time_ms(size_t young_num) const;
 347 
 348   double predict_non_young_other_time_ms(size_t non_young_num) const;
 349 
 350   double predict_base_elapsed_time_ms(size_t pending_cards) const;
 351   double predict_base_elapsed_time_ms(size_t pending_cards,
 352                                       size_t scanned_cards) const;
 353   size_t predict_bytes_to_copy(HeapRegion* hr) const;
 354   double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc) const;
 355 
 356   void set_recorded_rs_lengths(size_t rs_lengths);
 357 
 358   uint cset_region_length() const       { return young_cset_region_length() +
 359                                            old_cset_region_length(); }
 360   uint young_cset_region_length() const { return eden_cset_region_length() +
 361                                            survivor_cset_region_length(); }
 362 
 363   double predict_survivor_regions_evac_time() const;
 364 
 365   bool should_update_surv_rate_group_predictors() {
 366     return collector_state()->last_gc_was_young() && !collector_state()->in_marking_window();
 367   }
 368 
 369   void cset_regions_freed() {
 370     bool update = should_update_surv_rate_group_predictors();
 371 
 372     _short_lived_surv_rate_group->all_surviving_words_recorded(update);
 373     _survivor_surv_rate_group->all_surviving_words_recorded(update);
 374   }
 375 
 376   G1MMUTracker* mmu_tracker() {
 377     return _mmu_tracker;
 378   }
 379 
 380   const G1MMUTracker* mmu_tracker() const {
 381     return _mmu_tracker;
 382   }
 383 
 384   double max_pause_time_ms() const {
 385     return _mmu_tracker->max_gc_time() * 1000.0;
 386   }
 387 
 388   double predict_remark_time_ms() const;
 389 
 390   double predict_cleanup_time_ms() const;
 391 
 392   // Returns an estimate of the survival rate of the region at yg-age
 393   // "yg_age".
 394   double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const;
 395 
 396   double predict_yg_surv_rate(int age) const;
 397 
 398   double accum_yg_surv_rate_pred(int age) const;
 399 
 400 protected:
 401   virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;
 402   virtual double other_time_ms(double pause_time_ms) const;
 403 
 404   double young_other_time_ms() const;
 405   double non_young_other_time_ms() const;
 406   double constant_other_time_ms(double pause_time_ms) const;
 407 
 408   CollectionSetChooser* cset_chooser() const {
 409     return _cset_chooser;
 410   }
 411 
 412 private:
 413   // Statistics kept per GC stoppage, pause or full.
 414   TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
 415 
 416   // Add a new GC of the given duration and end time to the record.
 417   void update_recent_gc_times(double end_time_sec, double elapsed_ms);
 418 
 419   // The head of the list (via "next_in_collection_set()") representing the
 420   // current collection set. Set from the incrementally built collection
 421   // set at the start of the pause.
 422   HeapRegion* _collection_set;
 423 
 424   // The number of bytes in the collection set before the pause. Set from
 425   // the incrementally built collection set at the start of an evacuation
 426   // pause, and incremented in finalize_old_cset_part() when adding old regions
 427   // (if any) to the collection set.
 428   size_t _collection_set_bytes_used_before;
 429 
 430   // The number of bytes copied during the GC.
 431   size_t _bytes_copied_during_gc;
 432 
 433   // The associated information that is maintained while the incremental
 434   // collection set is being built with young regions. Used to populate
 435   // the recorded info for the evacuation pause.
 436 
 437   enum CSetBuildType {
 438     Active,             // We are actively building the collection set
 439     Inactive            // We are not actively building the collection set
 440   };
 441 
 442   CSetBuildType _inc_cset_build_state;
 443 
 444   // The head of the incrementally built collection set.
 445   HeapRegion* _inc_cset_head;
 446 
 447   // The tail of the incrementally built collection set.
 448   HeapRegion* _inc_cset_tail;
 449 
 450   // The number of bytes in the incrementally built collection set.
 451   // Used to set _collection_set_bytes_used_before at the start of
 452   // an evacuation pause.
 453   size_t _inc_cset_bytes_used_before;
 454 
 455   // Used to record the highest end of heap region in collection set
 456   HeapWord* _inc_cset_max_finger;
 457 
 458   // The RSet lengths recorded for regions in the CSet. It is updated
 459   // by the thread that adds a new region to the CSet. We assume that
 460   // only one thread can be allocating a new CSet region (currently,
 461   // it does so after taking the Heap_lock) hence no need to
 462   // synchronize updates to this field.
 463   size_t _inc_cset_recorded_rs_lengths;
 464 
 465   // A concurrent refinement thread periodically samples the young
 466   // region RSets and needs to update _inc_cset_recorded_rs_lengths as
 467   // the RSets grow. Instead of having to synchronize updates to that
 468   // field we accumulate them in this field and add it to
 469   // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
 470   ssize_t _inc_cset_recorded_rs_lengths_diffs;
 471 
 472   // The predicted elapsed time it will take to collect the regions in
 473   // the CSet. This is updated by the thread that adds a new region to
 474   // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
 475   // MT-safety assumptions.
 476   double _inc_cset_predicted_elapsed_time_ms;
 477 
 478   // See the comment for _inc_cset_recorded_rs_lengths_diffs.
 479   double _inc_cset_predicted_elapsed_time_ms_diffs;
 480 
 481   // Stash a pointer to the g1 heap.
 482   G1CollectedHeap* _g1;
 483 
 484   G1GCPhaseTimes* _phase_times;
 485 
 486   // The ratio of gc time to elapsed time, computed over recent pauses.
 487   double _recent_avg_pause_time_ratio;
 488 
 489   double recent_avg_pause_time_ratio() const {
 490     return _recent_avg_pause_time_ratio;
 491   }
 492 
 493   // This set of variables tracks the collector efficiency, in order to
 494   // determine whether we should initiate a new marking.
 495   double _mark_remark_start_sec;
 496   double _mark_cleanup_start_sec;
 497 
 498   // Updates the internal young list maximum and target lengths. Returns the
 499   // unbounded young list target length.
 500   uint update_young_list_max_and_target_length();
 501   uint update_young_list_max_and_target_length(size_t rs_lengths);
 502 
 503   // Update the young list target length either by setting it to the
 504   // desired fixed value or by calculating it using G1's pause
 505   // prediction model. If no rs_lengths parameter is passed, predict
 506   // the RS lengths using the prediction model, otherwise use the
 507   // given rs_lengths as the prediction.
 508   // Returns the unbounded young list target length.
 509   uint update_young_list_target_length(size_t rs_lengths);
 510 
 511   // Calculate and return the minimum desired young list target
 512   // length. This is the minimum desired young list length according
 513   // to the user's inputs.
 514   uint calculate_young_list_desired_min_length(uint base_min_length) const;
 515 
 516   // Calculate and return the maximum desired young list target
 517   // length. This is the maximum desired young list length according
 518   // to the user's inputs.
 519   uint calculate_young_list_desired_max_length() const;
 520 
 521   // Calculate and return the maximum young list target length that
 522   // can fit into the pause time goal. The parameters are: rs_lengths
 523   // represent the prediction of how large the young RSet lengths will
 524   // be, base_min_length is the already existing number of regions in
 525   // the young list, min_length and max_length are the desired min and
 526   // max young list length according to the user's inputs.
 527   uint calculate_young_list_target_length(size_t rs_lengths,
 528                                           uint base_min_length,
 529                                           uint desired_min_length,
 530                                           uint desired_max_length) const;
 531 
 532   // Result of the bounded_young_list_target_length() method, containing both the
 533   // bounded as well as the unbounded young list target lengths in this order.
 534   typedef Pair<uint, uint, StackObj> YoungTargetLengths;
 535   YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;
 536 
 537   void update_rs_lengths_prediction();
 538   void update_rs_lengths_prediction(size_t prediction);
 539 
 540   // Calculate and return chunk size (in number of regions) for parallel
 541   // concurrent mark cleanup.
 542   uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const;
 543 
 544   // Check whether a given young length (young_length) fits into the
 545   // given target pause time and whether the prediction for the amount
 546   // of objects to be copied for the given length will fit into the
 547   // given free space (expressed by base_free_regions).  It is used by
 548   // calculate_young_list_target_length().
 549   bool predict_will_fit(uint young_length, double base_time_ms,
 550                         uint base_free_regions, double target_pause_time_ms) const;
 551 
 552   // Calculate the minimum number of old regions we'll add to the CSet
 553   // during a mixed GC.
 554   uint calc_min_old_cset_length() const;
 555 
 556   // Calculate the maximum number of old regions we'll add to the CSet
 557   // during a mixed GC.
 558   uint calc_max_old_cset_length() const;
 559 
 560   // Returns the given amount of uncollected reclaimable space
 561   // as a percentage of the current heap capacity.
 562   double reclaimable_bytes_perc(size_t reclaimable_bytes) const;
 563 
 564   // Sets up marking if proper conditions are met.
 565   void maybe_start_marking();
 566 
 567   // The kind of STW pause.
 568   enum PauseKind {
 569     FullGC,
 570     YoungOnlyGC,
 571     MixedGC,
 572     LastYoungGC,
 573     InitialMarkGC,
 574     Cleanup,
 575     Remark
 576   };
 577 
 578   // Calculate PauseKind from internal state.
 579   PauseKind young_gc_pause_kind() const;
 580   // Record the given STW pause with the given start and end times (in s).
 581   void record_pause(PauseKind kind, double start, double end);
 582   // Indicate that we aborted marking before doing any mixed GCs.
 583   void abort_time_to_mixed_tracking();
 584 public:
 585 
 586   G1CollectorPolicy();
 587 
 588   virtual ~G1CollectorPolicy();
 589 
 590   virtual G1CollectorPolicy* as_g1_policy() { return this; }
 591 
 592   G1CollectorState* collector_state() const;
 593 
 594   G1GCPhaseTimes* phase_times() const { return _phase_times; }
 595 
 596   // Check the current value of the young list RSet lengths and
 597   // compare it against the last prediction. If the current value is
 598   // higher, recalculate the young list target length prediction.
 599   void revise_young_list_target_length_if_necessary();
 600 
 601   // This should be called after the heap is resized.
 602   void record_new_heap_size(uint new_number_of_regions);
 603 
 604   void init();
 605 
 606   virtual void note_gc_start(uint num_active_workers);
 607 
 608   // Create jstat counters for the policy.
 609   virtual void initialize_gc_policy_counters();
 610 
 611   virtual HeapWord* mem_allocate_work(size_t size,
 612                                       bool is_tlab,
 613                                       bool* gc_overhead_limit_was_exceeded);
 614 
 615   // This method controls how a collector handles one or more
 616   // of its generations being fully allocated.
 617   virtual HeapWord* satisfy_failed_allocation(size_t size,
 618                                               bool is_tlab);
 619 
 620   bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
 621 
 622   bool about_to_start_mixed_phase() const;
 623 
 624   // Record the start and end of an evacuation pause.
 625   void record_collection_pause_start(double start_time_sec);
 626   void record_collection_pause_end(double pause_time_ms, size_t cards_scanned);
 627 
 628   // Record the start and end of a full collection.
 629   void record_full_collection_start();
 630   void record_full_collection_end();
 631 
 632   // Must currently be called while the world is stopped.
 633   void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
 634 
 635   // Record start and end of remark.
 636   void record_concurrent_mark_remark_start();
 637   void record_concurrent_mark_remark_end();
 638 
 639   // Record start, end, and completion of cleanup.
 640   void record_concurrent_mark_cleanup_start();
 641   void record_concurrent_mark_cleanup_end();
 642   void record_concurrent_mark_cleanup_completed();
 643 
 644   // Records the information about the heap size for reporting in
 645   // print_detailed_heap_transition
 646   void record_heap_size_info_at_start(bool full);
 647 
 648   // Print heap sizing transition (with less and more detail).
 649 
 650   void print_heap_transition(size_t bytes_before) const;
 651   void print_heap_transition() const;
 652   void print_detailed_heap_transition(bool full = false) const;
 653 
 654   virtual void print_phases(double pause_time_sec);
 655 
 656   void record_stop_world_start();
 657   void record_concurrent_pause();
 658 
 659   // Record how much space we copied during a GC. This is typically
 660   // called when a GC alloc region is being retired.
 661   void record_bytes_copied_during_gc(size_t bytes) {
 662     _bytes_copied_during_gc += bytes;
 663   }
 664 
 665   // The amount of space we copied during a GC.
 666   size_t bytes_copied_during_gc() const {
 667     return _bytes_copied_during_gc;
 668   }
 669 
 670   size_t collection_set_bytes_used_before() const {
 671     return _collection_set_bytes_used_before;
 672   }
 673 
 674   // Determine whether there are candidate regions so that the
 675   // next GC should be mixed. The two action strings are used
 676   // in the ergo output when the method returns true or false.
 677   bool next_gc_should_be_mixed(const char* true_action_str,
 678                                const char* false_action_str) const;
 679 
 680   // Choose a new collection set.  Marks the chosen regions as being
 681   // "in_collection_set", and links them together.  The head and number of
 682   // the collection set are available via access methods.
 683   double finalize_young_cset_part(double target_pause_time_ms);
 684   virtual void finalize_old_cset_part(double time_remaining_ms);
 685 
 686   // The head of the list (via "next_in_collection_set()") representing the
 687   // current collection set.
 688   HeapRegion* collection_set() { return _collection_set; }
 689 
 690   void clear_collection_set() { _collection_set = NULL; }
 691 
 692   // Add old region "hr" to the CSet.
 693   void add_old_region_to_cset(HeapRegion* hr);
 694 
 695   // Incremental CSet Support
 696 
 697   // The head of the incrementally built collection set.
 698   HeapRegion* inc_cset_head() { return _inc_cset_head; }
 699 
 700   // The tail of the incrementally built collection set.
 701   HeapRegion* inc_set_tail() { return _inc_cset_tail; }
 702 
 703   // Initialize incremental collection set info.
 704   void start_incremental_cset_building();
 705 
 706   // Perform any final calculations on the incremental CSet fields
 707   // before we can use them.
 708   void finalize_incremental_cset_building();
 709 
 710   void clear_incremental_cset() {
 711     _inc_cset_head = NULL;
 712     _inc_cset_tail = NULL;
 713   }
 714 
 715   // Stop adding regions to the incremental collection set
 716   void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
 717 
 718   // Add information about hr to the aggregated information for the
 719   // incrementally built collection set.
 720   void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
 721 
 722   // Update information about hr in the aggregated information for
 723   // the incrementally built collection set.
 724   void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
 725 
 726 private:
 727   // Update the incremental cset information when adding a region
 728   // (should not be called directly).
 729   void add_region_to_incremental_cset_common(HeapRegion* hr);
 730 
 731   // Set the state to start a concurrent marking cycle and clear
 732   // _initiate_conc_mark_if_possible because it has now been
 733   // acted on.
 734   void initiate_conc_mark();
 735 
 736 public:
 737   // Add hr to the LHS of the incremental collection set.
 738   void add_region_to_incremental_cset_lhs(HeapRegion* hr);
 739 
 740   // Add hr to the RHS of the incremental collection set.
 741   void add_region_to_incremental_cset_rhs(HeapRegion* hr);
 742 
 743 #ifndef PRODUCT
 744   void print_collection_set(HeapRegion* list_head, outputStream* st);
 745 #endif // !PRODUCT
 746 
 747   // This sets the initiate_conc_mark_if_possible() flag to start a
 748   // new cycle, as long as we are not already in one. It's best if it
 749   // is called during a safepoint when the test whether a cycle is in
 750   // progress or not is stable.
 751   bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
 752 
 753   // This is called at the very beginning of an evacuation pause (it
 754   // has to be the first thing that the pause does). If
 755   // initiate_conc_mark_if_possible() is true, and the concurrent
 756   // marking thread has completed its work during the previous cycle,
 757   // it will set during_initial_mark_pause() to so that the pause does
 758   // the initial-mark work and start a marking cycle.
 759   void decide_on_conc_mark_initiation();
 760 
 761   // If an expansion would be appropriate, because recent GC overhead had
 762   // exceeded the desired limit, return an amount to expand by.
 763   virtual size_t expansion_amount() const;
 764 
 765   // Print tracing information.
 766   void print_tracing_info() const;
 767 
 768   // Print stats on young survival ratio
 769   void print_yg_surv_rate_info() const;
 770 
 771   void finished_recalculating_age_indexes(bool is_survivors) {
 772     if (is_survivors) {
 773       _survivor_surv_rate_group->finished_recalculating_age_indexes();
 774     } else {
 775       _short_lived_surv_rate_group->finished_recalculating_age_indexes();
 776     }
 777     // do that for any other surv rate groups
 778   }
 779 
 780   size_t young_list_target_length() const { return _young_list_target_length; }
 781 
 782   bool is_young_list_full() const;
 783 
 784   bool can_expand_young_list() const;
 785 
 786   uint young_list_max_length() const {
 787     return _young_list_max_length;
 788   }
 789 
 790   bool adaptive_young_list_length() const {
 791     return _young_gen_sizer->adaptive_young_list_length();
 792   }
 793 
 794   virtual bool should_process_references() const {
 795     return true;
 796   }
 797 
 798 private:
 799   //
 800   // Survivor regions policy.
 801   //
 802 
 803   // Current tenuring threshold, set to 0 if the collector reaches the
 804   // maximum amount of survivors regions.
 805   uint _tenuring_threshold;
 806 
 807   // The limit on the number of regions allocated for survivors.
 808   uint _max_survivor_regions;
 809 
 810   // For reporting purposes.
 811   // The value of _heap_bytes_before_gc is also used to calculate
 812   // the cost of copying.
 813 
 814   size_t _eden_used_bytes_before_gc;         // Eden occupancy before GC
 815   size_t _survivor_used_bytes_before_gc;     // Survivor occupancy before GC
 816   size_t _heap_used_bytes_before_gc;         // Heap occupancy before GC
 817   size_t _metaspace_used_bytes_before_gc;    // Metaspace occupancy before GC
 818 
 819   size_t _eden_capacity_bytes_before_gc;     // Eden capacity before GC
 820   size_t _heap_capacity_bytes_before_gc;     // Heap capacity before GC
 821 
 822   // The amount of survivor regions after a collection.
 823   uint _recorded_survivor_regions;
 824   // List of survivor regions.
 825   HeapRegion* _recorded_survivor_head;
 826   HeapRegion* _recorded_survivor_tail;
 827 
 828   ageTable _survivors_age_table;
 829 
 830 public:
 831   uint tenuring_threshold() const { return _tenuring_threshold; }
 832 
 833   static const uint REGIONS_UNLIMITED = (uint) -1;
 834 
 835   uint max_regions(InCSetState dest) const {
 836     switch (dest.value()) {
 837       case InCSetState::Young:
 838         return _max_survivor_regions;
 839       case InCSetState::Old:
 840         return REGIONS_UNLIMITED;
 841       default:
 842         assert(false, "Unknown dest state: " CSETSTATE_FORMAT, dest.value());
 843         break;
 844     }
 845     // keep some compilers happy
 846     return 0;
 847   }
 848 
 849   void note_start_adding_survivor_regions() {
 850     _survivor_surv_rate_group->start_adding_regions();
 851   }
 852 
 853   void note_stop_adding_survivor_regions() {
 854     _survivor_surv_rate_group->stop_adding_regions();
 855   }
 856 
 857   void record_survivor_regions(uint regions,
 858                                HeapRegion* head,
 859                                HeapRegion* tail) {
 860     _recorded_survivor_regions = regions;
 861     _recorded_survivor_head    = head;
 862     _recorded_survivor_tail    = tail;
 863   }
 864 
 865   uint recorded_survivor_regions() const {
 866     return _recorded_survivor_regions;
 867   }
 868 
 869   void record_age_table(ageTable* age_table) {
 870     _survivors_age_table.merge(age_table);
 871   }
 872 
 873   void update_max_gc_locker_expansion();
 874 
 875   // Calculates survivor space parameters.
 876   void update_survivors_policy();
 877 
 878   virtual void post_heap_initialize();
 879 };
 880 
 881 #endif // SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP