aoqi@0: /*
aoqi@0:  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
aoqi@0: #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
aoqi@0: 
aoqi@0: #include "gc_implementation/g1/collectionSetChooser.hpp"
aoqi@0: #include "gc_implementation/g1/g1MMUTracker.hpp"
aoqi@0: #include "memory/collectorPolicy.hpp"
aoqi@0: 
aoqi@0: // A G1CollectorPolicy makes policy decisions that determine the
aoqi@0: // characteristics of the collector.  Examples include:
aoqi@0: //   * choice of collection set.
aoqi@0: //   * when to collect.
aoqi@0: 
aoqi@0: class HeapRegion;
aoqi@0: class CollectionSetChooser;
aoqi@0: class G1GCPhaseTimes;
aoqi@0: 
aoqi@0: // TraceGen0Time collects data on _both_ young and mixed evacuation pauses
aoqi@0: // (the latter may contain non-young regions - i.e. regions that are
aoqi@0: // technically in Gen1) while TraceGen1Time collects data about full GCs.
aoqi@0: class TraceGen0TimeData : public CHeapObj<mtGC> {
aoqi@0:  private:
aoqi@0:   unsigned  _young_pause_num;
aoqi@0:   unsigned  _mixed_pause_num;
aoqi@0: 
aoqi@0:   NumberSeq _all_stop_world_times_ms;
aoqi@0:   NumberSeq _all_yield_times_ms;
aoqi@0: 
aoqi@0:   NumberSeq _total;
aoqi@0:   NumberSeq _other;
aoqi@0:   NumberSeq _root_region_scan_wait;
aoqi@0:   NumberSeq _parallel;
aoqi@0:   NumberSeq _ext_root_scan;
aoqi@0:   NumberSeq _satb_filtering;
aoqi@0:   NumberSeq _update_rs;
aoqi@0:   NumberSeq _scan_rs;
aoqi@0:   NumberSeq _obj_copy;
aoqi@0:   NumberSeq _termination;
aoqi@0:   NumberSeq _parallel_other;
aoqi@0:   NumberSeq _clear_ct;
aoqi@0: 
aoqi@0:   void print_summary(const char* str, const NumberSeq* seq) const;
aoqi@0:   void print_summary_sd(const char* str, const NumberSeq* seq) const;
aoqi@0: 
aoqi@0: public:
aoqi@0:    TraceGen0TimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
aoqi@0:   void record_start_collection(double time_to_stop_the_world_ms);
aoqi@0:   void record_yield_time(double yield_time_ms);
aoqi@0:   void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
aoqi@0:   void increment_young_collection_count();
aoqi@0:   void increment_mixed_collection_count();
aoqi@0:   void print() const;
aoqi@0: };
aoqi@0: 
aoqi@0: class TraceGen1TimeData : public CHeapObj<mtGC> {
aoqi@0:  private:
aoqi@0:   NumberSeq _all_full_gc_times;
aoqi@0: 
aoqi@0:  public:
aoqi@0:   void record_full_collection(double full_gc_time_ms);
aoqi@0:   void print() const;
aoqi@0: };
aoqi@0: 
aoqi@0: // There are three command line options related to the young gen size:
aoqi@0: // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
aoqi@0: // just a short form for NewSize==MaxNewSize). G1 will use its internal
aoqi@0: // heuristics to calculate the actual young gen size, so these options
aoqi@0: // basically only limit the range within which G1 can pick a young gen
aoqi@0: // size. Also, these are general options taking byte sizes. G1 will
aoqi@0: // internally work with a number of regions instead. So, some rounding
aoqi@0: // will occur.
aoqi@0: //
aoqi@0: // If nothing related to the the young gen size is set on the command
aoqi@0: // line we should allow the young gen to be between G1NewSizePercent
aoqi@0: // and G1MaxNewSizePercent of the heap size. This means that every time
aoqi@0: // the heap size changes, the limits for the young gen size will be
aoqi@0: // recalculated.
aoqi@0: //
aoqi@0: // If only -XX:NewSize is set we should use the specified value as the
aoqi@0: // minimum size for young gen. Still using G1MaxNewSizePercent of the
aoqi@0: // heap as maximum.
aoqi@0: //
aoqi@0: // If only -XX:MaxNewSize is set we should use the specified value as the
aoqi@0: // maximum size for young gen. Still using G1NewSizePercent of the heap
aoqi@0: // as minimum.
aoqi@0: //
aoqi@0: // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
aoqi@0: // No updates when the heap size changes. There is a special case when
aoqi@0: // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
aoqi@0: // different heuristic for calculating the collection set when we do mixed
aoqi@0: // collection.
aoqi@0: //
aoqi@0: // If only -XX:NewRatio is set we should use the specified ratio of the heap
aoqi@0: // as both min and max. This will be interpreted as "fixed" just like the
aoqi@0: // NewSize==MaxNewSize case above. But we will update the min and max
aoqi@0: // everytime the heap size changes.
aoqi@0: //
aoqi@0: // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
aoqi@0: // combined with either NewSize or MaxNewSize. (A warning message is printed.)
aoqi@0: class G1YoungGenSizer : public CHeapObj<mtGC> {
aoqi@0: private:
aoqi@0:   enum SizerKind {
aoqi@0:     SizerDefaults,
aoqi@0:     SizerNewSizeOnly,
aoqi@0:     SizerMaxNewSizeOnly,
aoqi@0:     SizerMaxAndNewSize,
aoqi@0:     SizerNewRatio
aoqi@0:   };
aoqi@0:   SizerKind _sizer_kind;
aoqi@0:   uint _min_desired_young_length;
aoqi@0:   uint _max_desired_young_length;
aoqi@0:   bool _adaptive_size;
aoqi@0:   uint calculate_default_min_length(uint new_number_of_heap_regions);
aoqi@0:   uint calculate_default_max_length(uint new_number_of_heap_regions);
aoqi@0: 
aoqi@0:   // Update the given values for minimum and maximum young gen length in regions
aoqi@0:   // given the number of heap regions depending on the kind of sizing algorithm.
aoqi@0:   void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
aoqi@0: 
aoqi@0: public:
aoqi@0:   G1YoungGenSizer();
aoqi@0:   // Calculate the maximum length of the young gen given the number of regions
aoqi@0:   // depending on the sizing algorithm.
aoqi@0:   uint max_young_length(uint number_of_heap_regions);
aoqi@0: 
aoqi@0:   void heap_size_changed(uint new_number_of_heap_regions);
aoqi@0:   uint min_desired_young_length() {
aoqi@0:     return _min_desired_young_length;
aoqi@0:   }
aoqi@0:   uint max_desired_young_length() {
aoqi@0:     return _max_desired_young_length;
aoqi@0:   }
aoqi@0:   bool adaptive_young_list_length() {
aoqi@0:     return _adaptive_size;
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: class G1CollectorPolicy: public CollectorPolicy {
aoqi@0: private:
aoqi@0:   // either equal to the number of parallel threads, if ParallelGCThreads
aoqi@0:   // has been set, or 1 otherwise
aoqi@0:   int _parallel_gc_threads;
aoqi@0: 
aoqi@0:   // The number of GC threads currently active.
aoqi@0:   uintx _no_of_gc_threads;
aoqi@0: 
aoqi@0:   enum SomePrivateConstants {
aoqi@0:     NumPrevPausesForHeuristics = 10
aoqi@0:   };
aoqi@0: 
aoqi@0:   G1MMUTracker* _mmu_tracker;
aoqi@0: 
aoqi@0:   void initialize_alignments();
aoqi@0:   void initialize_flags();
aoqi@0: 
aoqi@0:   CollectionSetChooser* _collectionSetChooser;
aoqi@0: 
aoqi@0:   double _full_collection_start_sec;
aoqi@0:   uint   _cur_collection_pause_used_regions_at_start;
aoqi@0: 
aoqi@0:   // These exclude marking times.
aoqi@0:   TruncatedSeq* _recent_gc_times_ms;
aoqi@0: 
aoqi@0:   TruncatedSeq* _concurrent_mark_remark_times_ms;
aoqi@0:   TruncatedSeq* _concurrent_mark_cleanup_times_ms;
aoqi@0: 
aoqi@0:   TraceGen0TimeData _trace_gen0_time_data;
aoqi@0:   TraceGen1TimeData _trace_gen1_time_data;
aoqi@0: 
aoqi@0:   double _stop_world_start;
aoqi@0: 
aoqi@0:   // indicates whether we are in young or mixed GC mode
aoqi@0:   bool _gcs_are_young;
aoqi@0: 
aoqi@0:   uint _young_list_target_length;
aoqi@0:   uint _young_list_fixed_length;
aoqi@0: 
aoqi@0:   // The max number of regions we can extend the eden by while the GC
aoqi@0:   // locker is active. This should be >= _young_list_target_length;
aoqi@0:   uint _young_list_max_length;
aoqi@0: 
aoqi@0:   bool                  _last_gc_was_young;
aoqi@0: 
aoqi@0:   bool                  _during_marking;
aoqi@0:   bool                  _in_marking_window;
aoqi@0:   bool                  _in_marking_window_im;
aoqi@0: 
aoqi@0:   SurvRateGroup*        _short_lived_surv_rate_group;
aoqi@0:   SurvRateGroup*        _survivor_surv_rate_group;
aoqi@0:   // add here any more surv rate groups
aoqi@0: 
aoqi@0:   double                _gc_overhead_perc;
aoqi@0: 
aoqi@0:   double _reserve_factor;
aoqi@0:   uint _reserve_regions;
aoqi@0: 
aoqi@0:   bool during_marking() {
aoqi@0:     return _during_marking;
aoqi@0:   }
aoqi@0: 
aoqi@0:   enum PredictionConstants {
aoqi@0:     TruncatedSeqLength = 10
aoqi@0:   };
aoqi@0: 
aoqi@0:   TruncatedSeq* _alloc_rate_ms_seq;
aoqi@0:   double        _prev_collection_pause_end_ms;
aoqi@0: 
aoqi@0:   TruncatedSeq* _rs_length_diff_seq;
aoqi@0:   TruncatedSeq* _cost_per_card_ms_seq;
aoqi@0:   TruncatedSeq* _young_cards_per_entry_ratio_seq;
aoqi@0:   TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
aoqi@0:   TruncatedSeq* _cost_per_entry_ms_seq;
aoqi@0:   TruncatedSeq* _mixed_cost_per_entry_ms_seq;
aoqi@0:   TruncatedSeq* _cost_per_byte_ms_seq;
aoqi@0:   TruncatedSeq* _constant_other_time_ms_seq;
aoqi@0:   TruncatedSeq* _young_other_cost_per_region_ms_seq;
aoqi@0:   TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
aoqi@0: 
aoqi@0:   TruncatedSeq* _pending_cards_seq;
aoqi@0:   TruncatedSeq* _rs_lengths_seq;
aoqi@0: 
aoqi@0:   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
aoqi@0: 
aoqi@0:   G1YoungGenSizer* _young_gen_sizer;
aoqi@0: 
aoqi@0:   uint _eden_cset_region_length;
aoqi@0:   uint _survivor_cset_region_length;
aoqi@0:   uint _old_cset_region_length;
aoqi@0: 
aoqi@0:   void init_cset_region_lengths(uint eden_cset_region_length,
aoqi@0:                                 uint survivor_cset_region_length);
aoqi@0: 
aoqi@0:   uint eden_cset_region_length()     { return _eden_cset_region_length;     }
aoqi@0:   uint survivor_cset_region_length() { return _survivor_cset_region_length; }
aoqi@0:   uint old_cset_region_length()      { return _old_cset_region_length;      }
aoqi@0: 
aoqi@0:   uint _free_regions_at_end_of_collection;
aoqi@0: 
aoqi@0:   size_t _recorded_rs_lengths;
aoqi@0:   size_t _max_rs_lengths;
aoqi@0:   double _sigma;
aoqi@0: 
aoqi@0:   size_t _rs_lengths_prediction;
aoqi@0: 
aoqi@0:   double sigma() { return _sigma; }
aoqi@0: 
aoqi@0:   // A function that prevents us putting too much stock in small sample
aoqi@0:   // sets.  Returns a number between 2.0 and 1.0, depending on the number
aoqi@0:   // of samples.  5 or more samples yields one; fewer scales linearly from
aoqi@0:   // 2.0 at 1 sample to 1.0 at 5.
aoqi@0:   double confidence_factor(int samples) {
aoqi@0:     if (samples > 4) return 1.0;
aoqi@0:     else return  1.0 + sigma() * ((double)(5 - samples))/2.0;
aoqi@0:   }
aoqi@0: 
aoqi@0:   double get_new_neg_prediction(TruncatedSeq* seq) {
aoqi@0:     return seq->davg() - sigma() * seq->dsd();
aoqi@0:   }
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0:   bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
aoqi@0: #endif // PRODUCT
aoqi@0: 
aoqi@0:   void adjust_concurrent_refinement(double update_rs_time,
aoqi@0:                                     double update_rs_processed_buffers,
aoqi@0:                                     double goal_ms);
aoqi@0: 
aoqi@0:   uintx no_of_gc_threads() { return _no_of_gc_threads; }
aoqi@0:   void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
aoqi@0: 
aoqi@0:   double _pause_time_target_ms;
aoqi@0: 
aoqi@0:   size_t _pending_cards;
aoqi@0: 
aoqi@0: public:
aoqi@0:   // Accessors
aoqi@0: 
aoqi@0:   void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
aoqi@0:     hr->set_young();
aoqi@0:     hr->install_surv_rate_group(_short_lived_surv_rate_group);
aoqi@0:     hr->set_young_index_in_cset(young_index_in_cset);
aoqi@0:   }
aoqi@0: 
aoqi@0:   void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
aoqi@0:     assert(hr->is_young() && hr->is_survivor(), "pre-condition");
aoqi@0:     hr->install_surv_rate_group(_survivor_surv_rate_group);
aoqi@0:     hr->set_young_index_in_cset(young_index_in_cset);
aoqi@0:   }
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0:   bool verify_young_ages();
aoqi@0: #endif // PRODUCT
aoqi@0: 
aoqi@0:   double get_new_prediction(TruncatedSeq* seq) {
aoqi@0:     return MAX2(seq->davg() + sigma() * seq->dsd(),
aoqi@0:                 seq->davg() * confidence_factor(seq->num()));
aoqi@0:   }
aoqi@0: 
aoqi@0:   void record_max_rs_lengths(size_t rs_lengths) {
aoqi@0:     _max_rs_lengths = rs_lengths;
aoqi@0:   }
aoqi@0: 
aoqi@0:   size_t predict_rs_length_diff() {
aoqi@0:     return (size_t) get_new_prediction(_rs_length_diff_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_alloc_rate_ms() {
aoqi@0:     return get_new_prediction(_alloc_rate_ms_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_cost_per_card_ms() {
aoqi@0:     return get_new_prediction(_cost_per_card_ms_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_rs_update_time_ms(size_t pending_cards) {
aoqi@0:     return (double) pending_cards * predict_cost_per_card_ms();
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_young_cards_per_entry_ratio() {
aoqi@0:     return get_new_prediction(_young_cards_per_entry_ratio_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_mixed_cards_per_entry_ratio() {
aoqi@0:     if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
aoqi@0:       return predict_young_cards_per_entry_ratio();
aoqi@0:     } else {
aoqi@0:       return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   size_t predict_young_card_num(size_t rs_length) {
aoqi@0:     return (size_t) ((double) rs_length *
aoqi@0:                      predict_young_cards_per_entry_ratio());
aoqi@0:   }
aoqi@0: 
aoqi@0:   size_t predict_non_young_card_num(size_t rs_length) {
aoqi@0:     return (size_t) ((double) rs_length *
aoqi@0:                      predict_mixed_cards_per_entry_ratio());
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_rs_scan_time_ms(size_t card_num) {
aoqi@0:     if (gcs_are_young()) {
aoqi@0:       return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
aoqi@0:     } else {
aoqi@0:       return predict_mixed_rs_scan_time_ms(card_num);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_mixed_rs_scan_time_ms(size_t card_num) {
aoqi@0:     if (_mixed_cost_per_entry_ms_seq->num() < 3) {
aoqi@0:       return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
aoqi@0:     } else {
aoqi@0:       return (double) (card_num *
aoqi@0:                        get_new_prediction(_mixed_cost_per_entry_ms_seq));
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
aoqi@0:     if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
aoqi@0:       return (1.1 * (double) bytes_to_copy) *
aoqi@0:               get_new_prediction(_cost_per_byte_ms_seq);
aoqi@0:     } else {
aoqi@0:       return (double) bytes_to_copy *
aoqi@0:              get_new_prediction(_cost_per_byte_ms_during_cm_seq);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_object_copy_time_ms(size_t bytes_to_copy) {
aoqi@0:     if (_in_marking_window && !_in_marking_window_im) {
aoqi@0:       return predict_object_copy_time_ms_during_cm(bytes_to_copy);
aoqi@0:     } else {
aoqi@0:       return (double) bytes_to_copy *
aoqi@0:               get_new_prediction(_cost_per_byte_ms_seq);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_constant_other_time_ms() {
aoqi@0:     return get_new_prediction(_constant_other_time_ms_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_young_other_time_ms(size_t young_num) {
aoqi@0:     return (double) young_num *
aoqi@0:            get_new_prediction(_young_other_cost_per_region_ms_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_non_young_other_time_ms(size_t non_young_num) {
aoqi@0:     return (double) non_young_num *
aoqi@0:            get_new_prediction(_non_young_other_cost_per_region_ms_seq);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_base_elapsed_time_ms(size_t pending_cards);
aoqi@0:   double predict_base_elapsed_time_ms(size_t pending_cards,
aoqi@0:                                       size_t scanned_cards);
aoqi@0:   size_t predict_bytes_to_copy(HeapRegion* hr);
aoqi@0:   double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc);
aoqi@0: 
aoqi@0:   void set_recorded_rs_lengths(size_t rs_lengths);
aoqi@0: 
aoqi@0:   uint cset_region_length()       { return young_cset_region_length() +
aoqi@0:                                            old_cset_region_length(); }
aoqi@0:   uint young_cset_region_length() { return eden_cset_region_length() +
aoqi@0:                                            survivor_cset_region_length(); }
aoqi@0: 
aoqi@0:   double predict_survivor_regions_evac_time();
aoqi@0: 
aoqi@0:   void cset_regions_freed() {
aoqi@0:     bool propagate = _last_gc_was_young && !_in_marking_window;
aoqi@0:     _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
aoqi@0:     _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
aoqi@0:     // also call it on any more surv rate groups
aoqi@0:   }
aoqi@0: 
aoqi@0:   G1MMUTracker* mmu_tracker() {
aoqi@0:     return _mmu_tracker;
aoqi@0:   }
aoqi@0: 
aoqi@0:   double max_pause_time_ms() {
aoqi@0:     return _mmu_tracker->max_gc_time() * 1000.0;
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_remark_time_ms() {
aoqi@0:     return get_new_prediction(_concurrent_mark_remark_times_ms);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_cleanup_time_ms() {
aoqi@0:     return get_new_prediction(_concurrent_mark_cleanup_times_ms);
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Returns an estimate of the survival rate of the region at yg-age
aoqi@0:   // "yg_age".
aoqi@0:   double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
aoqi@0:     TruncatedSeq* seq = surv_rate_group->get_seq(age);
aoqi@0:     if (seq->num() == 0)
aoqi@0:       gclog_or_tty->print("BARF! age is %d", age);
aoqi@0:     guarantee( seq->num() > 0, "invariant" );
aoqi@0:     double pred = get_new_prediction(seq);
aoqi@0:     if (pred > 1.0)
aoqi@0:       pred = 1.0;
aoqi@0:     return pred;
aoqi@0:   }
aoqi@0: 
aoqi@0:   double predict_yg_surv_rate(int age) {
aoqi@0:     return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
aoqi@0:   }
aoqi@0: 
aoqi@0:   double accum_yg_surv_rate_pred(int age) {
aoqi@0:     return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
aoqi@0:   }
aoqi@0: 
aoqi@0: private:
aoqi@0:   // Statistics kept per GC stoppage, pause or full.
aoqi@0:   TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
aoqi@0: 
aoqi@0:   // Add a new GC of the given duration and end time to the record.
aoqi@0:   void update_recent_gc_times(double end_time_sec, double elapsed_ms);
aoqi@0: 
aoqi@0:   // The head of the list (via "next_in_collection_set()") representing the
aoqi@0:   // current collection set. Set from the incrementally built collection
aoqi@0:   // set at the start of the pause.
aoqi@0:   HeapRegion* _collection_set;
aoqi@0: 
aoqi@0:   // The number of bytes in the collection set before the pause. Set from
aoqi@0:   // the incrementally built collection set at the start of an evacuation
aoqi@0:   // pause, and incremented in finalize_cset() when adding old regions
aoqi@0:   // (if any) to the collection set.
aoqi@0:   size_t _collection_set_bytes_used_before;
aoqi@0: 
aoqi@0:   // The number of bytes copied during the GC.
aoqi@0:   size_t _bytes_copied_during_gc;
aoqi@0: 
aoqi@0:   // The associated information that is maintained while the incremental
aoqi@0:   // collection set is being built with young regions. Used to populate
aoqi@0:   // the recorded info for the evacuation pause.
aoqi@0: 
aoqi@0:   enum CSetBuildType {
aoqi@0:     Active,             // We are actively building the collection set
aoqi@0:     Inactive            // We are not actively building the collection set
aoqi@0:   };
aoqi@0: 
aoqi@0:   CSetBuildType _inc_cset_build_state;
aoqi@0: 
aoqi@0:   // The head of the incrementally built collection set.
aoqi@0:   HeapRegion* _inc_cset_head;
aoqi@0: 
aoqi@0:   // The tail of the incrementally built collection set.
aoqi@0:   HeapRegion* _inc_cset_tail;
aoqi@0: 
aoqi@0:   // The number of bytes in the incrementally built collection set.
aoqi@0:   // Used to set _collection_set_bytes_used_before at the start of
aoqi@0:   // an evacuation pause.
aoqi@0:   size_t _inc_cset_bytes_used_before;
aoqi@0: 
aoqi@0:   // Used to record the highest end of heap region in collection set
aoqi@0:   HeapWord* _inc_cset_max_finger;
aoqi@0: 
aoqi@0:   // The RSet lengths recorded for regions in the CSet. It is updated
aoqi@0:   // by the thread that adds a new region to the CSet. We assume that
aoqi@0:   // only one thread can be allocating a new CSet region (currently,
aoqi@0:   // it does so after taking the Heap_lock) hence no need to
aoqi@0:   // synchronize updates to this field.
aoqi@0:   size_t _inc_cset_recorded_rs_lengths;
aoqi@0: 
aoqi@0:   // A concurrent refinement thread periodcially samples the young
aoqi@0:   // region RSets and needs to update _inc_cset_recorded_rs_lengths as
aoqi@0:   // the RSets grow. Instead of having to syncronize updates to that
aoqi@0:   // field we accumulate them in this field and add it to
aoqi@0:   // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
aoqi@0:   ssize_t _inc_cset_recorded_rs_lengths_diffs;
aoqi@0: 
aoqi@0:   // The predicted elapsed time it will take to collect the regions in
aoqi@0:   // the CSet. This is updated by the thread that adds a new region to
aoqi@0:   // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
aoqi@0:   // MT-safety assumptions.
aoqi@0:   double _inc_cset_predicted_elapsed_time_ms;
aoqi@0: 
aoqi@0:   // See the comment for _inc_cset_recorded_rs_lengths_diffs.
aoqi@0:   double _inc_cset_predicted_elapsed_time_ms_diffs;
aoqi@0: 
aoqi@0:   // Stash a pointer to the g1 heap.
aoqi@0:   G1CollectedHeap* _g1;
aoqi@0: 
aoqi@0:   G1GCPhaseTimes* _phase_times;
aoqi@0: 
aoqi@0:   // The ratio of gc time to elapsed time, computed over recent pauses.
aoqi@0:   double _recent_avg_pause_time_ratio;
aoqi@0: 
aoqi@0:   double recent_avg_pause_time_ratio() {
aoqi@0:     return _recent_avg_pause_time_ratio;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // At the end of a pause we check the heap occupancy and we decide
aoqi@0:   // whether we will start a marking cycle during the next pause. If
aoqi@0:   // we decide that we want to do that, we will set this parameter to
aoqi@0:   // true. So, this parameter will stay true between the end of a
aoqi@0:   // pause and the beginning of a subsequent pause (not necessarily
aoqi@0:   // the next one, see the comments on the next field) when we decide
aoqi@0:   // that we will indeed start a marking cycle and do the initial-mark
aoqi@0:   // work.
aoqi@0:   volatile bool _initiate_conc_mark_if_possible;
aoqi@0: 
aoqi@0:   // If initiate_conc_mark_if_possible() is set at the beginning of a
aoqi@0:   // pause, it is a suggestion that the pause should start a marking
aoqi@0:   // cycle by doing the initial-mark work. However, it is possible
aoqi@0:   // that the concurrent marking thread is still finishing up the
aoqi@0:   // previous marking cycle (e.g., clearing the next marking
aoqi@0:   // bitmap). If that is the case we cannot start a new cycle and
aoqi@0:   // we'll have to wait for the concurrent marking thread to finish
aoqi@0:   // what it is doing. In this case we will postpone the marking cycle
aoqi@0:   // initiation decision for the next pause. When we eventually decide
aoqi@0:   // to start a cycle, we will set _during_initial_mark_pause which
aoqi@0:   // will stay true until the end of the initial-mark pause and it's
aoqi@0:   // the condition that indicates that a pause is doing the
aoqi@0:   // initial-mark work.
aoqi@0:   volatile bool _during_initial_mark_pause;
aoqi@0: 
aoqi@0:   bool _last_young_gc;
aoqi@0: 
aoqi@0:   // This set of variables tracks the collector efficiency, in order to
aoqi@0:   // determine whether we should initiate a new marking.
aoqi@0:   double _cur_mark_stop_world_time_ms;
aoqi@0:   double _mark_remark_start_sec;
aoqi@0:   double _mark_cleanup_start_sec;
aoqi@0: 
aoqi@0:   // Update the young list target length either by setting it to the
aoqi@0:   // desired fixed value or by calculating it using G1's pause
aoqi@0:   // prediction model. If no rs_lengths parameter is passed, predict
aoqi@0:   // the RS lengths using the prediction model, otherwise use the
aoqi@0:   // given rs_lengths as the prediction.
aoqi@0:   void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
aoqi@0: 
aoqi@0:   // Calculate and return the minimum desired young list target
aoqi@0:   // length. This is the minimum desired young list length according
aoqi@0:   // to the user's inputs.
aoqi@0:   uint calculate_young_list_desired_min_length(uint base_min_length);
aoqi@0: 
aoqi@0:   // Calculate and return the maximum desired young list target
aoqi@0:   // length. This is the maximum desired young list length according
aoqi@0:   // to the user's inputs.
aoqi@0:   uint calculate_young_list_desired_max_length();
aoqi@0: 
aoqi@0:   // Calculate and return the maximum young list target length that
aoqi@0:   // can fit into the pause time goal. The parameters are: rs_lengths
aoqi@0:   // represent the prediction of how large the young RSet lengths will
aoqi@0:   // be, base_min_length is the alreay existing number of regions in
aoqi@0:   // the young list, min_length and max_length are the desired min and
aoqi@0:   // max young list length according to the user's inputs.
aoqi@0:   uint calculate_young_list_target_length(size_t rs_lengths,
aoqi@0:                                           uint base_min_length,
aoqi@0:                                           uint desired_min_length,
aoqi@0:                                           uint desired_max_length);
aoqi@0: 
aoqi@0:   // Check whether a given young length (young_length) fits into the
aoqi@0:   // given target pause time and whether the prediction for the amount
aoqi@0:   // of objects to be copied for the given length will fit into the
aoqi@0:   // given free space (expressed by base_free_regions).  It is used by
aoqi@0:   // calculate_young_list_target_length().
aoqi@0:   bool predict_will_fit(uint young_length, double base_time_ms,
aoqi@0:                         uint base_free_regions, double target_pause_time_ms);
aoqi@0: 
aoqi@0:   // Calculate the minimum number of old regions we'll add to the CSet
aoqi@0:   // during a mixed GC.
aoqi@0:   uint calc_min_old_cset_length();
aoqi@0: 
aoqi@0:   // Calculate the maximum number of old regions we'll add to the CSet
aoqi@0:   // during a mixed GC.
aoqi@0:   uint calc_max_old_cset_length();
aoqi@0: 
aoqi@0:   // Returns the given amount of uncollected reclaimable space
aoqi@0:   // as a percentage of the current heap capacity.
aoqi@0:   double reclaimable_bytes_perc(size_t reclaimable_bytes);
aoqi@0: 
aoqi@0: public:
aoqi@0: 
aoqi@0:   G1CollectorPolicy();
aoqi@0: 
aoqi@0:   virtual G1CollectorPolicy* as_g1_policy() { return this; }
aoqi@0: 
aoqi@0:   virtual CollectorPolicy::Name kind() {
aoqi@0:     return CollectorPolicy::G1CollectorPolicyKind;
aoqi@0:   }
aoqi@0: 
aoqi@0:   G1GCPhaseTimes* phase_times() const { return _phase_times; }
aoqi@0: 
aoqi@0:   // Check the current value of the young list RSet lengths and
aoqi@0:   // compare it against the last prediction. If the current value is
aoqi@0:   // higher, recalculate the young list target length prediction.
aoqi@0:   void revise_young_list_target_length_if_necessary();
aoqi@0: 
aoqi@0:   // This should be called after the heap is resized.
aoqi@0:   void record_new_heap_size(uint new_number_of_regions);
aoqi@0: 
aoqi@0:   void init();
aoqi@0: 
aoqi@0:   // Create jstat counters for the policy.
aoqi@0:   virtual void initialize_gc_policy_counters();
aoqi@0: 
aoqi@0:   virtual HeapWord* mem_allocate_work(size_t size,
aoqi@0:                                       bool is_tlab,
aoqi@0:                                       bool* gc_overhead_limit_was_exceeded);
aoqi@0: 
aoqi@0:   // This method controls how a collector handles one or more
aoqi@0:   // of its generations being fully allocated.
aoqi@0:   virtual HeapWord* satisfy_failed_allocation(size_t size,
aoqi@0:                                               bool is_tlab);
aoqi@0: 
aoqi@0:   BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
aoqi@0: 
aoqi@0:   bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
aoqi@0: 
aoqi@0:   // Record the start and end of an evacuation pause.
aoqi@0:   void record_collection_pause_start(double start_time_sec);
aoqi@0:   void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info);
aoqi@0: 
aoqi@0:   // Record the start and end of a full collection.
aoqi@0:   void record_full_collection_start();
aoqi@0:   void record_full_collection_end();
aoqi@0: 
aoqi@0:   // Must currently be called while the world is stopped.
aoqi@0:   void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
aoqi@0: 
aoqi@0:   // Record start and end of remark.
aoqi@0:   void record_concurrent_mark_remark_start();
aoqi@0:   void record_concurrent_mark_remark_end();
aoqi@0: 
aoqi@0:   // Record start, end, and completion of cleanup.
aoqi@0:   void record_concurrent_mark_cleanup_start();
aoqi@0:   void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
aoqi@0:   void record_concurrent_mark_cleanup_completed();
aoqi@0: 
aoqi@0:   // Records the information about the heap size for reporting in
aoqi@0:   // print_detailed_heap_transition
aoqi@0:   void record_heap_size_info_at_start(bool full);
aoqi@0: 
aoqi@0:   // Print heap sizing transition (with less and more detail).
aoqi@0:   void print_heap_transition();
aoqi@0:   void print_detailed_heap_transition(bool full = false);
aoqi@0: 
aoqi@0:   void record_stop_world_start();
aoqi@0:   void record_concurrent_pause();
aoqi@0: 
aoqi@0:   // Record how much space we copied during a GC. This is typically
aoqi@0:   // called when a GC alloc region is being retired.
aoqi@0:   void record_bytes_copied_during_gc(size_t bytes) {
aoqi@0:     _bytes_copied_during_gc += bytes;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // The amount of space we copied during a GC.
aoqi@0:   size_t bytes_copied_during_gc() {
aoqi@0:     return _bytes_copied_during_gc;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Determine whether there are candidate regions so that the
aoqi@0:   // next GC should be mixed. The two action strings are used
aoqi@0:   // in the ergo output when the method returns true or false.
aoqi@0:   bool next_gc_should_be_mixed(const char* true_action_str,
aoqi@0:                                const char* false_action_str);
aoqi@0: 
aoqi@0:   // Choose a new collection set.  Marks the chosen regions as being
aoqi@0:   // "in_collection_set", and links them together.  The head and number of
aoqi@0:   // the collection set are available via access methods.
aoqi@0:   void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info);
aoqi@0: 
aoqi@0:   // The head of the list (via "next_in_collection_set()") representing the
aoqi@0:   // current collection set.
aoqi@0:   HeapRegion* collection_set() { return _collection_set; }
aoqi@0: 
aoqi@0:   void clear_collection_set() { _collection_set = NULL; }
aoqi@0: 
aoqi@0:   // Add old region "hr" to the CSet.
aoqi@0:   void add_old_region_to_cset(HeapRegion* hr);
aoqi@0: 
aoqi@0:   // Incremental CSet Support
aoqi@0: 
aoqi@0:   // The head of the incrementally built collection set.
aoqi@0:   HeapRegion* inc_cset_head() { return _inc_cset_head; }
aoqi@0: 
aoqi@0:   // The tail of the incrementally built collection set.
aoqi@0:   HeapRegion* inc_set_tail() { return _inc_cset_tail; }
aoqi@0: 
aoqi@0:   // Initialize incremental collection set info.
aoqi@0:   void start_incremental_cset_building();
aoqi@0: 
aoqi@0:   // Perform any final calculations on the incremental CSet fields
aoqi@0:   // before we can use them.
aoqi@0:   void finalize_incremental_cset_building();
aoqi@0: 
aoqi@0:   void clear_incremental_cset() {
aoqi@0:     _inc_cset_head = NULL;
aoqi@0:     _inc_cset_tail = NULL;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Stop adding regions to the incremental collection set
aoqi@0:   void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
aoqi@0: 
aoqi@0:   // Add information about hr to the aggregated information for the
aoqi@0:   // incrementally built collection set.
aoqi@0:   void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
aoqi@0: 
aoqi@0:   // Update information about hr in the aggregated information for
aoqi@0:   // the incrementally built collection set.
aoqi@0:   void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
aoqi@0: 
aoqi@0: private:
aoqi@0:   // Update the incremental cset information when adding a region
aoqi@0:   // (should not be called directly).
aoqi@0:   void add_region_to_incremental_cset_common(HeapRegion* hr);
aoqi@0: 
aoqi@0: public:
aoqi@0:   // Add hr to the LHS of the incremental collection set.
aoqi@0:   void add_region_to_incremental_cset_lhs(HeapRegion* hr);
aoqi@0: 
aoqi@0:   // Add hr to the RHS of the incremental collection set.
aoqi@0:   void add_region_to_incremental_cset_rhs(HeapRegion* hr);
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0:   void print_collection_set(HeapRegion* list_head, outputStream* st);
aoqi@0: #endif // !PRODUCT
aoqi@0: 
aoqi@0:   bool initiate_conc_mark_if_possible()       { return _initiate_conc_mark_if_possible;  }
aoqi@0:   void set_initiate_conc_mark_if_possible()   { _initiate_conc_mark_if_possible = true;  }
aoqi@0:   void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
aoqi@0: 
aoqi@0:   bool during_initial_mark_pause()      { return _during_initial_mark_pause;  }
aoqi@0:   void set_during_initial_mark_pause()  { _during_initial_mark_pause = true;  }
aoqi@0:   void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
aoqi@0: 
aoqi@0:   // This sets the initiate_conc_mark_if_possible() flag to start a
aoqi@0:   // new cycle, as long as we are not already in one. It's best if it
aoqi@0:   // is called during a safepoint when the test whether a cycle is in
aoqi@0:   // progress or not is stable.
aoqi@0:   bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
aoqi@0: 
aoqi@0:   // This is called at the very beginning of an evacuation pause (it
aoqi@0:   // has to be the first thing that the pause does). If
aoqi@0:   // initiate_conc_mark_if_possible() is true, and the concurrent
aoqi@0:   // marking thread has completed its work during the previous cycle,
aoqi@0:   // it will set during_initial_mark_pause() to so that the pause does
aoqi@0:   // the initial-mark work and start a marking cycle.
aoqi@0:   void decide_on_conc_mark_initiation();
aoqi@0: 
aoqi@0:   // If an expansion would be appropriate, because recent GC overhead had
aoqi@0:   // exceeded the desired limit, return an amount to expand by.
aoqi@0:   size_t expansion_amount();
aoqi@0: 
aoqi@0:   // Print tracing information.
aoqi@0:   void print_tracing_info() const;
aoqi@0: 
aoqi@0:   // Print stats on young survival ratio
aoqi@0:   void print_yg_surv_rate_info() const;
aoqi@0: 
aoqi@0:   void finished_recalculating_age_indexes(bool is_survivors) {
aoqi@0:     if (is_survivors) {
aoqi@0:       _survivor_surv_rate_group->finished_recalculating_age_indexes();
aoqi@0:     } else {
aoqi@0:       _short_lived_surv_rate_group->finished_recalculating_age_indexes();
aoqi@0:     }
aoqi@0:     // do that for any other surv rate groups
aoqi@0:   }
aoqi@0: 
aoqi@0:   size_t young_list_target_length() const { return _young_list_target_length; }
aoqi@0: 
aoqi@0:   bool is_young_list_full() {
aoqi@0:     uint young_list_length = _g1->young_list()->length();
aoqi@0:     uint young_list_target_length = _young_list_target_length;
aoqi@0:     return young_list_length >= young_list_target_length;
aoqi@0:   }
aoqi@0: 
aoqi@0:   bool can_expand_young_list() {
aoqi@0:     uint young_list_length = _g1->young_list()->length();
aoqi@0:     uint young_list_max_length = _young_list_max_length;
aoqi@0:     return young_list_length < young_list_max_length;
aoqi@0:   }
aoqi@0: 
aoqi@0:   uint young_list_max_length() {
aoqi@0:     return _young_list_max_length;
aoqi@0:   }
aoqi@0: 
aoqi@0:   bool gcs_are_young() {
aoqi@0:     return _gcs_are_young;
aoqi@0:   }
aoqi@0:   void set_gcs_are_young(bool gcs_are_young) {
aoqi@0:     _gcs_are_young = gcs_are_young;
aoqi@0:   }
aoqi@0: 
aoqi@0:   bool adaptive_young_list_length() {
aoqi@0:     return _young_gen_sizer->adaptive_young_list_length();
aoqi@0:   }
aoqi@0: 
aoqi@0: private:
aoqi@0:   //
aoqi@0:   // Survivor regions policy.
aoqi@0:   //
aoqi@0: 
aoqi@0:   // Current tenuring threshold, set to 0 if the collector reaches the
aoqi@0:   // maximum amount of survivors regions.
aoqi@0:   uint _tenuring_threshold;
aoqi@0: 
aoqi@0:   // The limit on the number of regions allocated for survivors.
aoqi@0:   uint _max_survivor_regions;
aoqi@0: 
aoqi@0:   // For reporting purposes.
aoqi@0:   // The value of _heap_bytes_before_gc is also used to calculate
aoqi@0:   // the cost of copying.
aoqi@0: 
aoqi@0:   size_t _eden_used_bytes_before_gc;         // Eden occupancy before GC
aoqi@0:   size_t _survivor_used_bytes_before_gc;     // Survivor occupancy before GC
aoqi@0:   size_t _heap_used_bytes_before_gc;         // Heap occupancy before GC
aoqi@0:   size_t _metaspace_used_bytes_before_gc;    // Metaspace occupancy before GC
aoqi@0: 
aoqi@0:   size_t _eden_capacity_bytes_before_gc;     // Eden capacity before GC
aoqi@0:   size_t _heap_capacity_bytes_before_gc;     // Heap capacity before GC
aoqi@0: 
aoqi@0:   // The amount of survivor regions after a collection.
aoqi@0:   uint _recorded_survivor_regions;
aoqi@0:   // List of survivor regions.
aoqi@0:   HeapRegion* _recorded_survivor_head;
aoqi@0:   HeapRegion* _recorded_survivor_tail;
aoqi@0: 
aoqi@0:   ageTable _survivors_age_table;
aoqi@0: 
aoqi@0: public:
aoqi@0:   uint tenuring_threshold() const { return _tenuring_threshold; }
aoqi@0: 
aoqi@0:   inline GCAllocPurpose
aoqi@0:     evacuation_destination(HeapRegion* src_region, uint age, size_t word_sz) {
aoqi@0:       if (age < _tenuring_threshold && src_region->is_young()) {
aoqi@0:         return GCAllocForSurvived;
aoqi@0:       } else {
aoqi@0:         return GCAllocForTenured;
aoqi@0:       }
aoqi@0:   }
aoqi@0: 
aoqi@0:   inline bool track_object_age(GCAllocPurpose purpose) {
aoqi@0:     return purpose == GCAllocForSurvived;
aoqi@0:   }
aoqi@0: 
aoqi@0:   static const uint REGIONS_UNLIMITED = (uint) -1;
aoqi@0: 
aoqi@0:   uint max_regions(int purpose);
aoqi@0: 
aoqi@0:   // The limit on regions for a particular purpose is reached.
aoqi@0:   void note_alloc_region_limit_reached(int purpose) {
aoqi@0:     if (purpose == GCAllocForSurvived) {
aoqi@0:       _tenuring_threshold = 0;
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   void note_start_adding_survivor_regions() {
aoqi@0:     _survivor_surv_rate_group->start_adding_regions();
aoqi@0:   }
aoqi@0: 
aoqi@0:   void note_stop_adding_survivor_regions() {
aoqi@0:     _survivor_surv_rate_group->stop_adding_regions();
aoqi@0:   }
aoqi@0: 
aoqi@0:   void record_survivor_regions(uint regions,
aoqi@0:                                HeapRegion* head,
aoqi@0:                                HeapRegion* tail) {
aoqi@0:     _recorded_survivor_regions = regions;
aoqi@0:     _recorded_survivor_head    = head;
aoqi@0:     _recorded_survivor_tail    = tail;
aoqi@0:   }
aoqi@0: 
aoqi@0:   uint recorded_survivor_regions() {
aoqi@0:     return _recorded_survivor_regions;
aoqi@0:   }
aoqi@0: 
aoqi@0:   void record_thread_age_table(ageTable* age_table) {
aoqi@0:     _survivors_age_table.merge_par(age_table);
aoqi@0:   }
aoqi@0: 
aoqi@0:   void update_max_gc_locker_expansion();
aoqi@0: 
aoqi@0:   // Calculates survivor space parameters.
aoqi@0:   void update_survivors_policy();
aoqi@0: 
aoqi@0:   virtual void post_heap_initialize();
aoqi@0: };
aoqi@0: 
aoqi@0: // This should move to some place more general...
aoqi@0: 
aoqi@0: // If we have "n" measurements, and we've kept track of their "sum" and the
aoqi@0: // "sum_of_squares" of the measurements, this returns the variance of the
aoqi@0: // sequence.
aoqi@0: inline double variance(int n, double sum_of_squares, double sum) {
aoqi@0:   double n_d = (double)n;
aoqi@0:   double avg = sum/n_d;
aoqi@0:   return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
aoqi@0: }
aoqi@0: 
aoqi@0: #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP