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

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 *

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

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

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#ifndef SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP

#define SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP

#include "gc/g1/collectionSetChooser.hpp"

#include "gc/g1/g1CollectorState.hpp"

#include "gc/g1/g1GCPhaseTimes.hpp"

#include "gc/g1/g1InCSetState.hpp"

#include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"

#include "gc/g1/g1MMUTracker.hpp"

#include "gc/g1/g1Predictions.hpp"

#include "gc/shared/collectorPolicy.hpp"

#include "utilities/pair.hpp"

// A G1CollectorPolicy makes policy decisions that determine the

// characteristics of the collector.  Examples include:

//   * choice of collection set.

//   * when to collect.

class HeapRegion;

class CollectionSetChooser;

class G1IHOPControl;

class G1YoungGenSizer;

// TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses

// (the latter may contain non-young regions - i.e. regions that are

// technically in old) while TraceOldGenTime collects data about full GCs.

class TraceYoungGenTimeData : public CHeapObj<mtGC> {

 private:

  unsigned  _young_pause_num;

  unsigned  _mixed_pause_num;

  NumberSeq _all_stop_world_times_ms;

  NumberSeq _all_yield_times_ms;

  NumberSeq _total;

  NumberSeq _other;

  NumberSeq _root_region_scan_wait;

  NumberSeq _parallel;

  NumberSeq _ext_root_scan;

  NumberSeq _satb_filtering;

  NumberSeq _update_rs;

  NumberSeq _scan_rs;

  NumberSeq _obj_copy;

  NumberSeq _termination;

  NumberSeq _parallel_other;

  NumberSeq _clear_ct;

  void print_summary(const char* str, const NumberSeq* seq) const;

  void print_summary_sd(const char* str, const NumberSeq* seq) const;

public:

   TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {};

  void record_start_collection(double time_to_stop_the_world_ms);

  void record_yield_time(double yield_time_ms);

  void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);

  void increment_young_collection_count();

  void increment_mixed_collection_count();

  void print() const;

};

class TraceOldGenTimeData : public CHeapObj<mtGC> {

 private:

  NumberSeq _all_full_gc_times;

 public:

  void record_full_collection(double full_gc_time_ms);

  void print() const;

};

class G1CollectorPolicy: public CollectorPolicy {

 private:

  G1IHOPControl* _ihop_control;

  G1IHOPControl* create_ihop_control() const;

  // Update the IHOP control with necessary statistics.

  void update_ihop_prediction(double mutator_time_s,

                              size_t mutator_alloc_bytes,

                              size_t young_gen_size);

  void report_ihop_statistics();

  G1Predictions _predictor;

  double get_new_prediction(TruncatedSeq const* seq) const;

  size_t get_new_size_prediction(TruncatedSeq const* seq) const;

  // either equal to the number of parallel threads, if ParallelGCThreads

  // has been set, or 1 otherwise

  int _parallel_gc_threads;

  // The number of GC threads currently active.

  uintx _no_of_gc_threads;

  G1MMUTracker* _mmu_tracker;

  void initialize_alignments();

  void initialize_flags();

  CollectionSetChooser* _cset_chooser;

  double _full_collection_start_sec;

  // These exclude marking times.

  TruncatedSeq* _recent_gc_times_ms;

  TruncatedSeq* _concurrent_mark_remark_times_ms;

  TruncatedSeq* _concurrent_mark_cleanup_times_ms;

  // Ratio check data for determining if heap growth is necessary.

  uint _ratio_over_threshold_count;

  double _ratio_over_threshold_sum;

  uint _pauses_since_start;

  TraceYoungGenTimeData _trace_young_gen_time_data;

  TraceOldGenTimeData   _trace_old_gen_time_data;

  double _stop_world_start;

  uint _young_list_target_length;

  uint _young_list_fixed_length;

  // The max number of regions we can extend the eden by while the GC

  // locker is active. This should be >= _young_list_target_length;

  uint _young_list_max_length;

  SurvRateGroup* _short_lived_surv_rate_group;

  SurvRateGroup* _survivor_surv_rate_group;

  // add here any more surv rate groups

  double _gc_overhead_perc;

  double _reserve_factor;

  uint   _reserve_regions;

  enum PredictionConstants {

    TruncatedSeqLength = 10,

    NumPrevPausesForHeuristics = 10,

    // MinOverThresholdForGrowth must be less than NumPrevPausesForHeuristics,

    // representing the minimum number of pause time ratios that exceed

    // GCTimeRatio before a heap expansion will be triggered.

    MinOverThresholdForGrowth = 4

  };

  TruncatedSeq* _alloc_rate_ms_seq;

  double        _prev_collection_pause_end_ms;

  TruncatedSeq* _rs_length_diff_seq;

  TruncatedSeq* _cost_per_card_ms_seq;

  TruncatedSeq* _cost_scan_hcc_seq;

  TruncatedSeq* _young_cards_per_entry_ratio_seq;

  TruncatedSeq* _mixed_cards_per_entry_ratio_seq;

  TruncatedSeq* _cost_per_entry_ms_seq;

  TruncatedSeq* _mixed_cost_per_entry_ms_seq;

  TruncatedSeq* _cost_per_byte_ms_seq;

  TruncatedSeq* _constant_other_time_ms_seq;

  TruncatedSeq* _young_other_cost_per_region_ms_seq;

  TruncatedSeq* _non_young_other_cost_per_region_ms_seq;

  TruncatedSeq* _pending_cards_seq;

  TruncatedSeq* _rs_lengths_seq;

  TruncatedSeq* _cost_per_byte_ms_during_cm_seq;

  G1YoungGenSizer* _young_gen_sizer;

  uint _eden_cset_region_length;

  uint _survivor_cset_region_length;

  uint _old_cset_region_length;

  void init_cset_region_lengths(uint eden_cset_region_length,

                                uint survivor_cset_region_length);

  uint eden_cset_region_length() const     { return _eden_cset_region_length;     }

  uint survivor_cset_region_length() const { return _survivor_cset_region_length; }

  uint old_cset_region_length() const      { return _old_cset_region_length;      }

  uint _free_regions_at_end_of_collection;

  size_t _recorded_rs_lengths;

  size_t _max_rs_lengths;

  size_t _rs_lengths_prediction;

#ifndef PRODUCT

  bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);

#endif // PRODUCT

  void adjust_concurrent_refinement(double update_rs_time,

                                    double update_rs_processed_buffers,

                                    double goal_ms);

  uintx no_of_gc_threads() { return _no_of_gc_threads; }

  void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }

  double _pause_time_target_ms;

  size_t _pending_cards;

  // The amount of allocated bytes in old gen during the last mutator and the following

  // young GC phase.

  size_t _bytes_allocated_in_old_since_last_gc;

  G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;

public:

  const G1Predictions& predictor() const { return _predictor; }

  // Add the given number of bytes to the total number of allocated bytes in the old gen.

  void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }

  // Accessors

  void set_region_eden(HeapRegion* hr, int young_index_in_cset) {

    hr->set_eden();

    hr->install_surv_rate_group(_short_lived_surv_rate_group);

    hr->set_young_index_in_cset(young_index_in_cset);

  }

  void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {

    assert(hr->is_survivor(), "pre-condition");

    hr->install_surv_rate_group(_survivor_surv_rate_group);

    hr->set_young_index_in_cset(young_index_in_cset);

  }

#ifndef PRODUCT

  bool verify_young_ages();

#endif // PRODUCT

  void record_max_rs_lengths(size_t rs_lengths) {

    _max_rs_lengths = rs_lengths;

  }

  size_t predict_rs_length_diff() const;

  double predict_alloc_rate_ms() const;

  double predict_cost_per_card_ms() const;

  double predict_scan_hcc_ms() const;

  double predict_rs_update_time_ms(size_t pending_cards) const;

  double predict_young_cards_per_entry_ratio() const;

  double predict_mixed_cards_per_entry_ratio() const;

  size_t predict_young_card_num(size_t rs_length) const;

  size_t predict_non_young_card_num(size_t rs_length) const;

  double predict_rs_scan_time_ms(size_t card_num) const;

  double predict_mixed_rs_scan_time_ms(size_t card_num) const;

  double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const;

  double predict_object_copy_time_ms(size_t bytes_to_copy) const;

  double predict_constant_other_time_ms() const;

  double predict_young_other_time_ms(size_t young_num) const;

  double predict_non_young_other_time_ms(size_t non_young_num) const;

  double predict_base_elapsed_time_ms(size_t pending_cards) const;

  double predict_base_elapsed_time_ms(size_t pending_cards,

                                      size_t scanned_cards) const;

  size_t predict_bytes_to_copy(HeapRegion* hr) const;

  double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc) const;

  void set_recorded_rs_lengths(size_t rs_lengths);

  uint cset_region_length() const       { return young_cset_region_length() +

                                           old_cset_region_length(); }

  uint young_cset_region_length() const { return eden_cset_region_length() +

                                           survivor_cset_region_length(); }

  double predict_survivor_regions_evac_time() const;

  bool should_update_surv_rate_group_predictors() {

    return collector_state()->last_gc_was_young() && !collector_state()->in_marking_window();

  }

  void cset_regions_freed() {

    bool update = should_update_surv_rate_group_predictors();

    _short_lived_surv_rate_group->all_surviving_words_recorded(update);

    _survivor_surv_rate_group->all_surviving_words_recorded(update);

  }

  G1MMUTracker* mmu_tracker() {

    return _mmu_tracker;

  }

  const G1MMUTracker* mmu_tracker() const {

    return _mmu_tracker;

  }

  double max_pause_time_ms() const {

    return _mmu_tracker->max_gc_time() * 1000.0;

  }

  double predict_remark_time_ms() const;

  double predict_cleanup_time_ms() const;

  // Returns an estimate of the survival rate of the region at yg-age

  // "yg_age".

  double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const;

  double predict_yg_surv_rate(int age) const;

  double accum_yg_surv_rate_pred(int age) const;

protected:

  virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;

  virtual double other_time_ms(double pause_time_ms) const;

  double young_other_time_ms() const;

  double non_young_other_time_ms() const;

  double constant_other_time_ms(double pause_time_ms) const;

  CollectionSetChooser* cset_chooser() const {

    return _cset_chooser;

  }

private:

  // Statistics kept per GC stoppage, pause or full.

  TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;

  // Add a new GC of the given duration and end time to the record.

  void update_recent_gc_times(double end_time_sec, double elapsed_ms);

  // The head of the list (via "next_in_collection_set()") representing the

  // current collection set. Set from the incrementally built collection

  // set at the start of the pause.

  HeapRegion* _collection_set;

  // The number of bytes in the collection set before the pause. Set from

  // the incrementally built collection set at the start of an evacuation

  // pause, and incremented in finalize_old_cset_part() when adding old regions

  // (if any) to the collection set.

  size_t _collection_set_bytes_used_before;

  // The number of bytes copied during the GC.

  size_t _bytes_copied_during_gc;

  // The associated information that is maintained while the incremental

  // collection set is being built with young regions. Used to populate

  // the recorded info for the evacuation pause.

  enum CSetBuildType {

    Active,             // We are actively building the collection set

    Inactive            // We are not actively building the collection set

  };

  CSetBuildType _inc_cset_build_state;

  // The head of the incrementally built collection set.

  HeapRegion* _inc_cset_head;

  // The tail of the incrementally built collection set.

  HeapRegion* _inc_cset_tail;

  // The number of bytes in the incrementally built collection set.

  // Used to set _collection_set_bytes_used_before at the start of

  // an evacuation pause.

  size_t _inc_cset_bytes_used_before;

  // Used to record the highest end of heap region in collection set

  HeapWord* _inc_cset_max_finger;

  // The RSet lengths recorded for regions in the CSet. It is updated

  // by the thread that adds a new region to the CSet. We assume that

  // only one thread can be allocating a new CSet region (currently,

  // it does so after taking the Heap_lock) hence no need to

  // synchronize updates to this field.

  size_t _inc_cset_recorded_rs_lengths;

  // A concurrent refinement thread periodically samples the young

  // region RSets and needs to update _inc_cset_recorded_rs_lengths as

  // the RSets grow. Instead of having to synchronize updates to that

  // field we accumulate them in this field and add it to

  // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.

  ssize_t _inc_cset_recorded_rs_lengths_diffs;

  // The predicted elapsed time it will take to collect the regions in

  // the CSet. This is updated by the thread that adds a new region to

  // the CSet. See the comment for _inc_cset_recorded_rs_lengths about

  // MT-safety assumptions.

  double _inc_cset_predicted_elapsed_time_ms;

  // See the comment for _inc_cset_recorded_rs_lengths_diffs.

  double _inc_cset_predicted_elapsed_time_ms_diffs;

  // Stash a pointer to the g1 heap.

  G1CollectedHeap* _g1;

  G1GCPhaseTimes* _phase_times;

  // The ratio of gc time to elapsed time, computed over recent pauses,

  // and the ratio for just the last pause.

  double _recent_avg_pause_time_ratio;

  double _last_pause_time_ratio;

  double recent_avg_pause_time_ratio() const {

    return _recent_avg_pause_time_ratio;

  }

  // This set of variables tracks the collector efficiency, in order to

  // determine whether we should initiate a new marking.

  double _mark_remark_start_sec;

  double _mark_cleanup_start_sec;

  // Updates the internal young list maximum and target lengths. Returns the

  // unbounded young list target length.

  uint update_young_list_max_and_target_length();

  uint update_young_list_max_and_target_length(size_t rs_lengths);

  // Update the young list target length either by setting it to the

  // desired fixed value or by calculating it using G1's pause

  // prediction model. If no rs_lengths parameter is passed, predict

  // the RS lengths using the prediction model, otherwise use the

  // given rs_lengths as the prediction.

  // Returns the unbounded young list target length.

  uint update_young_list_target_length(size_t rs_lengths);

  // Calculate and return the minimum desired young list target

  // length. This is the minimum desired young list length according

  // to the user's inputs.

  uint calculate_young_list_desired_min_length(uint base_min_length) const;

  // Calculate and return the maximum desired young list target

  // length. This is the maximum desired young list length according

  // to the user's inputs.

  uint calculate_young_list_desired_max_length() const;

  // Calculate and return the maximum young list target length that

  // can fit into the pause time goal. The parameters are: rs_lengths

  // represent the prediction of how large the young RSet lengths will

  // be, base_min_length is the already existing number of regions in

  // the young list, min_length and max_length are the desired min and

  // max young list length according to the user's inputs.

  uint calculate_young_list_target_length(size_t rs_lengths,

                                          uint base_min_length,

                                          uint desired_min_length,

                                          uint desired_max_length) const;

  // Result of the bounded_young_list_target_length() method, containing both the

  // bounded as well as the unbounded young list target lengths in this order.

  typedef Pair<uint, uint, StackObj> YoungTargetLengths;

  YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;

  void update_rs_lengths_prediction();

  void update_rs_lengths_prediction(size_t prediction);

  // Calculate and return chunk size (in number of regions) for parallel

  // concurrent mark cleanup.

  uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const;

  // Check whether a given young length (young_length) fits into the

  // given target pause time and whether the prediction for the amount

  // of objects to be copied for the given length will fit into the

  // given free space (expressed by base_free_regions).  It is used by

  // calculate_young_list_target_length().

  bool predict_will_fit(uint young_length, double base_time_ms,

                        uint base_free_regions, double target_pause_time_ms) const;

  // Calculate the minimum number of old regions we'll add to the CSet

  // during a mixed GC.