jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp

Mon, 09 Aug 2010 05:41:05 -0700

author: jcoomes
date: Mon, 09 Aug 2010 05:41:05 -0700
changeset 2064: 5f429ee79634
parent 2062: 0ce1569c90e5
child 2314: f95d63e2154a
permissions: -rw-r--r--

6966222: G1: simplify TaskQueue overflow handling
Reviewed-by: tonyp, ysr

 /*
  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * 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.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // 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;
 // Yes, this is a bit unpleasant... but it saves replicating the same thing
 // over and over again and introducing subtle problems through small typos and
 // cutting and pasting mistakes. The macros below introduces a number
 // sequnce into the following two classes and the methods that access it.
 #define define_num_seq(name)                                                  \
 private:                                                                      \
   NumberSeq _all_##name##_times_ms;                                           \
 public:                                                                       \
   void record_##name##_time_ms(double ms) {                                   \
     _all_##name##_times_ms.add(ms);                                           \
   }                                                                           \
   NumberSeq* get_##name##_seq() {                                             \
     return &_all_##name##_times_ms;                                           \
   }
 class MainBodySummary;
 class PauseSummary: public CHeapObj {
   define_num_seq(total)
     define_num_seq(other)
 public:
   virtual MainBodySummary*    main_body_summary()    { return NULL; }
 };
 class MainBodySummary: public CHeapObj {
   define_num_seq(satb_drain) // optional
   define_num_seq(parallel) // parallel only
     define_num_seq(ext_root_scan)
     define_num_seq(mark_stack_scan)
     define_num_seq(update_rs)
     define_num_seq(scan_rs)
     define_num_seq(obj_copy)
     define_num_seq(termination) // parallel only
     define_num_seq(parallel_other) // parallel only
   define_num_seq(mark_closure)
   define_num_seq(clear_ct)  // parallel only
 };
 class Summary: public PauseSummary,
                public MainBodySummary {
 public:
   virtual MainBodySummary*    main_body_summary()    { return this; }
 };
 class G1CollectorPolicy: public CollectorPolicy {
 protected:
   // The number of pauses during the execution.
   long _n_pauses;
   // either equal to the number of parallel threads, if ParallelGCThreads
   // has been set, or 1 otherwise
   int _parallel_gc_threads;
   enum SomePrivateConstants {
     NumPrevPausesForHeuristics = 10
   };
   G1MMUTracker* _mmu_tracker;
   void initialize_flags();
   void initialize_all() {
     initialize_flags();
     initialize_size_info();
     initialize_perm_generation(PermGen::MarkSweepCompact);
   }
   virtual size_t default_init_heap_size() {
     // Pick some reasonable default.
     return 8*M;
   }
   double _cur_collection_start_sec;
   size_t _cur_collection_pause_used_at_start_bytes;
   size_t _cur_collection_pause_used_regions_at_start;
   size_t _prev_collection_pause_used_at_end_bytes;
   double _cur_collection_par_time_ms;
   double _cur_satb_drain_time_ms;
   double _cur_clear_ct_time_ms;
   bool   _satb_drain_time_set;
 #ifndef PRODUCT
   // Card Table Count Cache stats
   double _min_clear_cc_time_ms;         // min
   double _max_clear_cc_time_ms;         // max
   double _cur_clear_cc_time_ms;         // clearing time during current pause
   double _cum_clear_cc_time_ms;         // cummulative clearing time
   jlong  _num_cc_clears;                // number of times the card count cache has been cleared
 #endif
   double _cur_CH_strong_roots_end_sec;
   double _cur_CH_strong_roots_dur_ms;
   double _cur_G1_strong_roots_end_sec;
   double _cur_G1_strong_roots_dur_ms;
   // Statistics for recent GC pauses.  See below for how indexed.
   TruncatedSeq* _recent_CH_strong_roots_times_ms;
   TruncatedSeq* _recent_G1_strong_roots_times_ms;
   TruncatedSeq* _recent_evac_times_ms;
   // These exclude marking times.
   TruncatedSeq* _recent_pause_times_ms;
   TruncatedSeq* _recent_gc_times_ms;
   TruncatedSeq* _recent_CS_bytes_used_before;
   TruncatedSeq* _recent_CS_bytes_surviving;
   TruncatedSeq* _recent_rs_sizes;
   TruncatedSeq* _concurrent_mark_init_times_ms;
   TruncatedSeq* _concurrent_mark_remark_times_ms;
   TruncatedSeq* _concurrent_mark_cleanup_times_ms;
   Summary*           _summary;
   NumberSeq* _all_pause_times_ms;
   NumberSeq* _all_full_gc_times_ms;
   double _stop_world_start;
   NumberSeq* _all_stop_world_times_ms;
   NumberSeq* _all_yield_times_ms;
   size_t     _region_num_young;
   size_t     _region_num_tenured;
   size_t     _prev_region_num_young;
   size_t     _prev_region_num_tenured;
   NumberSeq* _all_mod_union_times_ms;
   int        _aux_num;
   NumberSeq* _all_aux_times_ms;
   double*    _cur_aux_start_times_ms;
   double*    _cur_aux_times_ms;
   bool*      _cur_aux_times_set;
   double* _par_last_gc_worker_start_times_ms;
   double* _par_last_ext_root_scan_times_ms;
   double* _par_last_mark_stack_scan_times_ms;
   double* _par_last_update_rs_times_ms;
   double* _par_last_update_rs_processed_buffers;
   double* _par_last_scan_rs_times_ms;
   double* _par_last_obj_copy_times_ms;
   double* _par_last_termination_times_ms;
   double* _par_last_termination_attempts;
   double* _par_last_gc_worker_end_times_ms;
   // indicates that we are in young GC mode
   bool _in_young_gc_mode;
   // indicates whether we are in full young or partially young GC mode
   bool _full_young_gcs;
   // if true, then it tries to dynamically adjust the length of the
   // young list
   bool _adaptive_young_list_length;
   size_t _young_list_min_length;
   size_t _young_list_target_length;
   size_t _young_list_fixed_length;
   size_t _young_cset_length;
   bool   _last_young_gc_full;
   unsigned              _full_young_pause_num;
   unsigned              _partial_young_pause_num;
   bool                  _during_marking;
   bool                  _in_marking_window;
   bool                  _in_marking_window_im;
   SurvRateGroup*        _short_lived_surv_rate_group;
   SurvRateGroup*        _survivor_surv_rate_group;
   // add here any more surv rate groups
   double                _gc_overhead_perc;
   bool during_marking() {
     return _during_marking;
   }
   // <NEW PREDICTION>
 private:
   enum PredictionConstants {
     TruncatedSeqLength = 10
   };
   TruncatedSeq* _alloc_rate_ms_seq;
   double        _prev_collection_pause_end_ms;
   TruncatedSeq* _pending_card_diff_seq;
   TruncatedSeq* _rs_length_diff_seq;
   TruncatedSeq* _cost_per_card_ms_seq;
   TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
   TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
   TruncatedSeq* _cost_per_entry_ms_seq;
   TruncatedSeq* _partially_young_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* _scanned_cards_seq;
   TruncatedSeq* _rs_lengths_seq;
   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
   TruncatedSeq* _young_gc_eff_seq;
   TruncatedSeq* _max_conc_overhead_seq;
   size_t _recorded_young_regions;
   size_t _recorded_non_young_regions;
   size_t _recorded_region_num;
   size_t _free_regions_at_end_of_collection;
   size_t _recorded_rs_lengths;
   size_t _max_rs_lengths;
   size_t _recorded_marked_bytes;
   size_t _recorded_young_bytes;
   size_t _predicted_pending_cards;
   size_t _predicted_cards_scanned;
   size_t _predicted_rs_lengths;
   size_t _predicted_bytes_to_copy;
   double _predicted_survival_ratio;
   double _predicted_rs_update_time_ms;
   double _predicted_rs_scan_time_ms;
   double _predicted_object_copy_time_ms;
   double _predicted_constant_other_time_ms;
   double _predicted_young_other_time_ms;
   double _predicted_non_young_other_time_ms;
   double _predicted_pause_time_ms;
   double _vtime_diff_ms;
   double _recorded_young_free_cset_time_ms;
   double _recorded_non_young_free_cset_time_ms;
   double _sigma;
   double _expensive_region_limit_ms;
   size_t _rs_lengths_prediction;
   size_t _known_garbage_bytes;
   double _known_garbage_ratio;
   double sigma() {
     return _sigma;
   }
   // A function that prevents us putting too much stock in small sample
   // sets.  Returns a number between 2.0 and 1.0, depending on the number
   // of samples.  5 or more samples yields one; fewer scales linearly from
   // 2.0 at 1 sample to 1.0 at 5.
   double confidence_factor(int samples) {
     if (samples > 4) return 1.0;
     else return  1.0 + sigma() * ((double)(5 - samples))/2.0;
   }
   double get_new_neg_prediction(TruncatedSeq* seq) {
     return seq->davg() - sigma() * seq->dsd();
   }
 #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);
 protected:
   double _pause_time_target_ms;
   double _recorded_young_cset_choice_time_ms;
   double _recorded_non_young_cset_choice_time_ms;
   bool   _within_target;
   size_t _pending_cards;
   size_t _max_pending_cards;
 public:
   void set_region_short_lived(HeapRegion* hr) {
     hr->install_surv_rate_group(_short_lived_surv_rate_group);
   }
   void set_region_survivors(HeapRegion* hr) {
     hr->install_surv_rate_group(_survivor_surv_rate_group);
   }
 #ifndef PRODUCT
   bool verify_young_ages();
 #endif // PRODUCT
   double get_new_prediction(TruncatedSeq* seq) {
     return MAX2(seq->davg() + sigma() * seq->dsd(),
                 seq->davg() * confidence_factor(seq->num()));
   }
   size_t young_cset_length() {
     return _young_cset_length;
   }
   void record_max_rs_lengths(size_t rs_lengths) {
     _max_rs_lengths = rs_lengths;
   }
   size_t predict_pending_card_diff() {
     double prediction = get_new_neg_prediction(_pending_card_diff_seq);
     if (prediction < 0.00001)
       return 0;
     else
       return (size_t) prediction;
   }
   size_t predict_pending_cards() {
     size_t max_pending_card_num = _g1->max_pending_card_num();
     size_t diff = predict_pending_card_diff();
     size_t prediction;
     if (diff > max_pending_card_num)
       prediction = max_pending_card_num;
     else
       prediction = max_pending_card_num - diff;
     return prediction;
   }
   size_t predict_rs_length_diff() {
     return (size_t) get_new_prediction(_rs_length_diff_seq);
   }
   double predict_alloc_rate_ms() {
     return get_new_prediction(_alloc_rate_ms_seq);
   }
   double predict_cost_per_card_ms() {
     return get_new_prediction(_cost_per_card_ms_seq);
   }
   double predict_rs_update_time_ms(size_t pending_cards) {
     return (double) pending_cards * predict_cost_per_card_ms();
   }
   double predict_fully_young_cards_per_entry_ratio() {
     return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
   }
   double predict_partially_young_cards_per_entry_ratio() {
     if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
       return predict_fully_young_cards_per_entry_ratio();
     else
       return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
   }
   size_t predict_young_card_num(size_t rs_length) {
     return (size_t) ((double) rs_length *
                      predict_fully_young_cards_per_entry_ratio());
   }
   size_t predict_non_young_card_num(size_t rs_length) {
     return (size_t) ((double) rs_length *
                      predict_partially_young_cards_per_entry_ratio());
   }
   double predict_rs_scan_time_ms(size_t card_num) {
     if (full_young_gcs())
       return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
     else
       return predict_partially_young_rs_scan_time_ms(card_num);
   }
   double predict_partially_young_rs_scan_time_ms(size_t card_num) {
     if (_partially_young_cost_per_entry_ms_seq->num() < 3)
       return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
     else
       return (double) card_num *
         get_new_prediction(_partially_young_cost_per_entry_ms_seq);
   }
   double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
     if (_cost_per_byte_ms_during_cm_seq->num() < 3)
       return 1.1 * (double) bytes_to_copy *
         get_new_prediction(_cost_per_byte_ms_seq);
     else
       return (double) bytes_to_copy *
         get_new_prediction(_cost_per_byte_ms_during_cm_seq);
   }
   double predict_object_copy_time_ms(size_t bytes_to_copy) {
     if (_in_marking_window && !_in_marking_window_im)
       return predict_object_copy_time_ms_during_cm(bytes_to_copy);
     else
       return (double) bytes_to_copy *
         get_new_prediction(_cost_per_byte_ms_seq);
   }
   double predict_constant_other_time_ms() {
     return get_new_prediction(_constant_other_time_ms_seq);
   }
   double predict_young_other_time_ms(size_t young_num) {
     return
       (double) young_num *
       get_new_prediction(_young_other_cost_per_region_ms_seq);
   }
   double predict_non_young_other_time_ms(size_t non_young_num) {
     return
       (double) non_young_num *
       get_new_prediction(_non_young_other_cost_per_region_ms_seq);
   }
   void check_if_region_is_too_expensive(double predicted_time_ms);
   double predict_young_collection_elapsed_time_ms(size_t adjustment);
   double predict_base_elapsed_time_ms(size_t pending_cards);
   double predict_base_elapsed_time_ms(size_t pending_cards,
                                       size_t scanned_cards);
   size_t predict_bytes_to_copy(HeapRegion* hr);
   double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
     // for use by: calculate_young_list_target_length(rs_length)
   bool predict_will_fit(size_t young_region_num,
                         double base_time_ms,
                         size_t init_free_regions,
                         double target_pause_time_ms);
   void start_recording_regions();
   void record_cset_region_info(HeapRegion* hr, bool young);
   void record_non_young_cset_region(HeapRegion* hr);
   void set_recorded_young_regions(size_t n_regions);
   void set_recorded_young_bytes(size_t bytes);
   void set_recorded_rs_lengths(size_t rs_lengths);
   void set_predicted_bytes_to_copy(size_t bytes);
   void end_recording_regions();
   void record_vtime_diff_ms(double vtime_diff_ms) {
     _vtime_diff_ms = vtime_diff_ms;
   }
   void record_young_free_cset_time_ms(double time_ms) {
     _recorded_young_free_cset_time_ms = time_ms;
   }
   void record_non_young_free_cset_time_ms(double time_ms) {
     _recorded_non_young_free_cset_time_ms = time_ms;
   }
   double predict_young_gc_eff() {
     return get_new_neg_prediction(_young_gc_eff_seq);
   }
   double predict_survivor_regions_evac_time();
   // </NEW PREDICTION>
 public:
   void cset_regions_freed() {
     bool propagate = _last_young_gc_full && !_in_marking_window;
     _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
     _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
     // also call it on any more surv rate groups
   }
   void set_known_garbage_bytes(size_t known_garbage_bytes) {
     _known_garbage_bytes = known_garbage_bytes;
     size_t heap_bytes = _g1->capacity();
     _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
   }
   void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
     guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
     _known_garbage_bytes -= known_garbage_bytes;
     size_t heap_bytes = _g1->capacity();
     _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
   }
   G1MMUTracker* mmu_tracker() {
     return _mmu_tracker;
   }
   double max_pause_time_ms() {
     return _mmu_tracker->max_gc_time() * 1000.0;
   }
   double predict_init_time_ms() {
     return get_new_prediction(_concurrent_mark_init_times_ms);
   }
   double predict_remark_time_ms() {
     return get_new_prediction(_concurrent_mark_remark_times_ms);
   }
   double predict_cleanup_time_ms() {
     return get_new_prediction(_concurrent_mark_cleanup_times_ms);
   }
   // 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) {
     TruncatedSeq* seq = surv_rate_group->get_seq(age);
     if (seq->num() == 0)
       gclog_or_tty->print("BARF! age is %d", age);
     guarantee( seq->num() > 0, "invariant" );
     double pred = get_new_prediction(seq);
     if (pred > 1.0)
       pred = 1.0;
     return pred;
   }
   double predict_yg_surv_rate(int age) {
     return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
   }
   double accum_yg_surv_rate_pred(int age) {
     return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
   }
 protected:
   void print_stats(int level, const char* str, double value);
   void print_stats(int level, const char* str, int value);
   void print_par_stats(int level, const char* str, double* data) {
     print_par_stats(level, str, data, true);
   }
   void print_par_stats(int level, const char* str, double* data, bool summary);
   void print_par_sizes(int level, const char* str, double* data, bool summary);
   void check_other_times(int level,
                          NumberSeq* other_times_ms,
                          NumberSeq* calc_other_times_ms) const;
   void print_summary (PauseSummary* stats) const;
   void print_summary (int level, const char* str, NumberSeq* seq) const;
   void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
   double avg_value (double* data);
   double max_value (double* data);
   double sum_of_values (double* data);
   double max_sum (double* data1, double* data2);
   int _last_satb_drain_processed_buffers;
   int _last_update_rs_processed_buffers;
   double _last_pause_time_ms;
   size_t _bytes_in_to_space_before_gc;
   size_t _bytes_in_to_space_after_gc;
   size_t bytes_in_to_space_during_gc() {
     return
       _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc;
   }
   size_t _bytes_in_collection_set_before_gc;
   // Used to count used bytes in CS.
   friend class CountCSClosure;
   // Statistics kept per GC stoppage, pause or full.
   TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
   // We track markings.
   int _num_markings;
   double _mark_thread_startup_sec;       // Time at startup of marking thread
   // 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 regions in the collection set. Set from the incrementally
   // built collection set at the start of an evacuation pause.
   size_t _collection_set_size;
   // 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.
   size_t _collection_set_bytes_used_before;
   // 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 regions in the incrementally built collection set.
   // Used to set _collection_set_size at the start of an evacuation
   // pause.
   size_t _inc_cset_size;
   // Used as the index in the surving young words structure
   // which tracks the amount of space, for each young region,
   // that survives the pause.
   size_t _inc_cset_young_index;
   // 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 number of recorded used bytes in the young regions
   // of the collection set. This is the sum of the used() bytes
   // of retired young regions in the collection set.
   size_t _inc_cset_recorded_young_bytes;
   // The RSet lengths recorded for regions in the collection set
   // (updated by the periodic sampling of the regions in the
   // young list/collection set).
   size_t _inc_cset_recorded_rs_lengths;
   // The predicted elapsed time it will take to collect the regions
   // in the collection set (updated by the periodic sampling of the
   // regions in the young list/collection set).
   double _inc_cset_predicted_elapsed_time_ms;
   // The predicted bytes to copy for the regions in the collection
   // set (updated by the periodic sampling of the regions in the
   // young list/collection set).
   size_t _inc_cset_predicted_bytes_to_copy;
   // Info about marking.
   int _n_marks; // Sticky at 2, so we know when we've done at least 2.
   // The number of collection pauses at the end of the last mark.
   size_t _n_pauses_at_mark_end;
   // Stash a pointer to the g1 heap.
   G1CollectedHeap* _g1;
   // The average time in ms per collection pause, averaged over recent pauses.
   double recent_avg_time_for_pauses_ms();
   // The average time in ms for processing CollectedHeap strong roots, per
   // collection pause, averaged over recent pauses.
   double recent_avg_time_for_CH_strong_ms();
   // The average time in ms for processing the G1 remembered set, per
   // pause, averaged over recent pauses.
   double recent_avg_time_for_G1_strong_ms();
   // The average time in ms for "evacuating followers", per pause, averaged
   // over recent pauses.
   double recent_avg_time_for_evac_ms();
   // The number of "recent" GCs recorded in the number sequences
   int number_of_recent_gcs();
   // The average survival ratio, computed by the total number of bytes
   // suriviving / total number of bytes before collection over the last
   // several recent pauses.
   double recent_avg_survival_fraction();
   // The survival fraction of the most recent pause; if there have been no
   // pauses, returns 1.0.
   double last_survival_fraction();
   // Returns a "conservative" estimate of the recent survival rate, i.e.,
   // one that may be higher than "recent_avg_survival_fraction".
   // This is conservative in several ways:
   //   If there have been few pauses, it will assume a potential high
   //     variance, and err on the side of caution.
   //   It puts a lower bound (currently 0.1) on the value it will return.
   //   To try to detect phase changes, if the most recent pause ("latest") has a
   //     higher-than average ("avg") survival rate, it returns that rate.
   // "work" version is a utility function; young is restricted to young regions.
   double conservative_avg_survival_fraction_work(double avg,
                                                  double latest);
   // The arguments are the two sequences that keep track of the number of bytes
   //   surviving and the total number of bytes before collection, resp.,
   //   over the last evereal recent pauses
   // Returns the survival rate for the category in the most recent pause.
   // If there have been no pauses, returns 1.0.
   double last_survival_fraction_work(TruncatedSeq* surviving,
                                      TruncatedSeq* before);
   // The arguments are the two sequences that keep track of the number of bytes
   //   surviving and the total number of bytes before collection, resp.,
   //   over the last several recent pauses
   // Returns the average survival ration over the last several recent pauses
   // If there have been no pauses, return 1.0
   double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
                                            TruncatedSeq* before);
   double conservative_avg_survival_fraction() {
     double avg = recent_avg_survival_fraction();
     double latest = last_survival_fraction();
     return conservative_avg_survival_fraction_work(avg, latest);
   }
   // The ratio of gc time to elapsed time, computed over recent pauses.
   double _recent_avg_pause_time_ratio;
   double recent_avg_pause_time_ratio() {
     return _recent_avg_pause_time_ratio;
   }
   // Number of pauses between concurrent marking.
   size_t _pauses_btwn_concurrent_mark;
   size_t _n_marks_since_last_pause;
   // At the end of a pause we check the heap occupancy and we decide
   // whether we will start a marking cycle during the next pause. If
   // we decide that we want to do that, we will set this parameter to
   // true. So, this parameter will stay true between the end of a
   // pause and the beginning of a subsequent pause (not necessarily
   // the next one, see the comments on the next field) when we decide
   // that we will indeed start a marking cycle and do the initial-mark
   // work.
   volatile bool _initiate_conc_mark_if_possible;
   // If initiate_conc_mark_if_possible() is set at the beginning of a
   // pause, it is a suggestion that the pause should start a marking
   // cycle by doing the initial-mark work. However, it is possible
   // that the concurrent marking thread is still finishing up the
   // previous marking cycle (e.g., clearing the next marking
   // bitmap). If that is the case we cannot start a new cycle and
   // we'll have to wait for the concurrent marking thread to finish
   // what it is doing. In this case we will postpone the marking cycle
   // initiation decision for the next pause. When we eventually decide
   // to start a cycle, we will set _during_initial_mark_pause which
   // will stay true until the end of the initial-mark pause and it's
   // the condition that indicates that a pause is doing the
   // initial-mark work.
   volatile bool _during_initial_mark_pause;
   bool _should_revert_to_full_young_gcs;
   bool _last_full_young_gc;
   // This set of variables tracks the collector efficiency, in order to
   // determine whether we should initiate a new marking.
   double _cur_mark_stop_world_time_ms;
   double _mark_init_start_sec;
   double _mark_remark_start_sec;
   double _mark_cleanup_start_sec;
   double _mark_closure_time_ms;
   void   calculate_young_list_min_length();
   void   calculate_young_list_target_length();
   void   calculate_young_list_target_length(size_t rs_lengths);
 public:
   G1CollectorPolicy();
   virtual G1CollectorPolicy* as_g1_policy() { return this; }
   virtual CollectorPolicy::Name kind() {
     return CollectorPolicy::G1CollectorPolicyKind;
   }
   void check_prediction_validity();
   size_t bytes_in_collection_set() {
     return _bytes_in_collection_set_before_gc;
   }
   size_t bytes_in_to_space() {
     return bytes_in_to_space_during_gc();
   }
   unsigned calc_gc_alloc_time_stamp() {
     return _all_pause_times_ms->num() + 1;
   }
 protected:
   // Count the number of bytes used in the CS.
   void count_CS_bytes_used();
   // Together these do the base cleanup-recording work.  Subclasses might
   // want to put something between them.
   void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
                                                 size_t max_live_bytes);
   void record_concurrent_mark_cleanup_end_work2();
 public:
   virtual void init();
   // Create jstat counters for the policy.
   virtual void initialize_gc_policy_counters();
   virtual HeapWord* mem_allocate_work(size_t size,
                                       bool is_tlab,
                                       bool* gc_overhead_limit_was_exceeded);
   // This method controls how a collector handles one or more
   // of its generations being fully allocated.
   virtual HeapWord* satisfy_failed_allocation(size_t size,
                                               bool is_tlab);
   BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
   GenRemSet::Name  rem_set_name()     { return GenRemSet::CardTable; }
   // The number of collection pauses so far.
   long n_pauses() const { return _n_pauses; }
   // Update the heuristic info to record a collection pause of the given
   // start time, where the given number of bytes were used at the start.
   // This may involve changing the desired size of a collection set.
   virtual void record_stop_world_start();
   virtual void record_collection_pause_start(double start_time_sec,
                                              size_t start_used);
   // Must currently be called while the world is stopped.
   virtual void record_concurrent_mark_init_start();
   virtual void record_concurrent_mark_init_end();
   void record_concurrent_mark_init_end_pre(double
                                            mark_init_elapsed_time_ms);
   void record_mark_closure_time(double mark_closure_time_ms);
   virtual void record_concurrent_mark_remark_start();
   virtual void record_concurrent_mark_remark_end();
   virtual void record_concurrent_mark_cleanup_start();
   virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
                                                   size_t max_live_bytes);
   virtual void record_concurrent_mark_cleanup_completed();
   virtual void record_concurrent_pause();
   virtual void record_concurrent_pause_end();
   virtual void record_collection_pause_end_CH_strong_roots();
   virtual void record_collection_pause_end_G1_strong_roots();
   virtual void record_collection_pause_end();
   // Record the fact that a full collection occurred.
   virtual void record_full_collection_start();
   virtual void record_full_collection_end();
   void record_gc_worker_start_time(int worker_i, double ms) {
     _par_last_gc_worker_start_times_ms[worker_i] = ms;
   }
   void record_ext_root_scan_time(int worker_i, double ms) {
     _par_last_ext_root_scan_times_ms[worker_i] = ms;
   }
   void record_mark_stack_scan_time(int worker_i, double ms) {
     _par_last_mark_stack_scan_times_ms[worker_i] = ms;
   }
   void record_satb_drain_time(double ms) {
     _cur_satb_drain_time_ms = ms;
     _satb_drain_time_set    = true;
   }
   void record_satb_drain_processed_buffers (int processed_buffers) {
     _last_satb_drain_processed_buffers = processed_buffers;
   }
   void record_mod_union_time(double ms) {
     _all_mod_union_times_ms->add(ms);
   }
   void record_update_rs_time(int thread, double ms) {
     _par_last_update_rs_times_ms[thread] = ms;
   }
   void record_update_rs_processed_buffers (int thread,
                                            double processed_buffers) {
     _par_last_update_rs_processed_buffers[thread] = processed_buffers;
   }
   void record_scan_rs_time(int thread, double ms) {
     _par_last_scan_rs_times_ms[thread] = ms;
   }
   void reset_obj_copy_time(int thread) {
     _par_last_obj_copy_times_ms[thread] = 0.0;
   }
   void reset_obj_copy_time() {
     reset_obj_copy_time(0);
   }
   void record_obj_copy_time(int thread, double ms) {
     _par_last_obj_copy_times_ms[thread] += ms;
   }
   void record_termination(int thread, double ms, size_t attempts) {
     _par_last_termination_times_ms[thread] = ms;
     _par_last_termination_attempts[thread] = (double) attempts;
   }
   void record_gc_worker_end_time(int worker_i, double ms) {
     _par_last_gc_worker_end_times_ms[worker_i] = ms;
   }
   void record_pause_time_ms(double ms) {
     _last_pause_time_ms = ms;
   }
   void record_clear_ct_time(double ms) {
     _cur_clear_ct_time_ms = ms;
   }
   void record_par_time(double ms) {
     _cur_collection_par_time_ms = ms;
   }
   void record_aux_start_time(int i) {
     guarantee(i < _aux_num, "should be within range");
     _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
   }
   void record_aux_end_time(int i) {
     guarantee(i < _aux_num, "should be within range");
     double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
     _cur_aux_times_set[i] = true;
     _cur_aux_times_ms[i] += ms;
   }
 #ifndef PRODUCT
   void record_cc_clear_time(double ms) {
     if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
       _min_clear_cc_time_ms = ms;
     if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
       _max_clear_cc_time_ms = ms;
     _cur_clear_cc_time_ms = ms;
     _cum_clear_cc_time_ms += ms;
     _num_cc_clears++;
   }
 #endif
   // Record the fact that "bytes" bytes allocated in a region.
   void record_before_bytes(size_t bytes);
   void record_after_bytes(size_t bytes);
   // Returns "true" if this is a good time to do a collection pause.
   // The "word_size" argument, if non-zero, indicates the size of an
   // allocation request that is prompting this query.
   virtual bool should_do_collection_pause(size_t word_size) = 0;
   // Choose a new collection set.  Marks the chosen regions as being
   // "in_collection_set", and links them together.  The head and number of
   // the collection set are available via access methods.
   virtual void choose_collection_set(double target_pause_time_ms) = 0;
   // The head of the list (via "next_in_collection_set()") representing the
   // current collection set.
   HeapRegion* collection_set() { return _collection_set; }
   void clear_collection_set() { _collection_set = NULL; }
   // The number of elements in the current collection set.
   size_t collection_set_size() { return _collection_set_size; }
   // Add "hr" to the CS.
   void add_to_collection_set(HeapRegion* hr);
   // Incremental CSet Support
   // The head of the incrementally built collection set.
   HeapRegion* inc_cset_head() { return _inc_cset_head; }
   // The tail of the incrementally built collection set.
   HeapRegion* inc_set_tail() { return _inc_cset_tail; }
   // The number of elements in the incrementally built collection set.
   size_t inc_cset_size() { return _inc_cset_size; }
   // Initialize incremental collection set info.
   void start_incremental_cset_building();
   void clear_incremental_cset() {
     _inc_cset_head = NULL;
     _inc_cset_tail = NULL;
   }
   // Stop adding regions to the incremental collection set
   void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
   // Add/remove information about hr to the aggregated information
   // for the incrementally built collection set.
   void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
   void remove_from_incremental_cset_info(HeapRegion* hr);
   // Update information about hr in the aggregated information for
   // the incrementally built collection set.
   void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
 private:
   // Update the incremental cset information when adding a region
   // (should not be called directly).
   void add_region_to_incremental_cset_common(HeapRegion* hr);
 public:
   // Add hr to the LHS of the incremental collection set.
   void add_region_to_incremental_cset_lhs(HeapRegion* hr);
   // Add hr to the RHS of the incremental collection set.
   void add_region_to_incremental_cset_rhs(HeapRegion* hr);
 #ifndef PRODUCT
   void print_collection_set(HeapRegion* list_head, outputStream* st);
 #endif // !PRODUCT
   bool initiate_conc_mark_if_possible()       { return _initiate_conc_mark_if_possible;  }
   void set_initiate_conc_mark_if_possible()   { _initiate_conc_mark_if_possible = true;  }
   void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
   bool during_initial_mark_pause()      { return _during_initial_mark_pause;  }
   void set_during_initial_mark_pause()  { _during_initial_mark_pause = true;  }
   void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
   // This sets the initiate_conc_mark_if_possible() flag to start a
   // new cycle, as long as we are not already in one. It's best if it
   // is called during a safepoint when the test whether a cycle is in
   // progress or not is stable.
   bool force_initial_mark_if_outside_cycle();
   // This is called at the very beginning of an evacuation pause (it
   // has to be the first thing that the pause does). If
   // initiate_conc_mark_if_possible() is true, and the concurrent
   // marking thread has completed its work during the previous cycle,
   // it will set during_initial_mark_pause() to so that the pause does
   // the initial-mark work and start a marking cycle.
   void decide_on_conc_mark_initiation();
   // If an expansion would be appropriate, because recent GC overhead had
   // exceeded the desired limit, return an amount to expand by.
   virtual size_t expansion_amount();
   // note start of mark thread
   void note_start_of_mark_thread();
   // The marked bytes of the "r" has changed; reclassify it's desirability
   // for marking.  Also asserts that "r" is eligible for a CS.
   virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
 #ifndef PRODUCT
   // Check any appropriate marked bytes info, asserting false if
   // something's wrong, else returning "true".
   virtual bool assertMarkedBytesDataOK() = 0;
 #endif
   // Print tracing information.
   void print_tracing_info() const;
   // Print stats on young survival ratio
   void print_yg_surv_rate_info() const;
   void finished_recalculating_age_indexes(bool is_survivors) {
     if (is_survivors) {
       _survivor_surv_rate_group->finished_recalculating_age_indexes();
     } else {
       _short_lived_surv_rate_group->finished_recalculating_age_indexes();
     }
     // do that for any other surv rate groups
   }
   bool should_add_next_region_to_young_list();
   bool in_young_gc_mode() {
     return _in_young_gc_mode;
   }
   void set_in_young_gc_mode(bool in_young_gc_mode) {
     _in_young_gc_mode = in_young_gc_mode;
   }
   bool full_young_gcs() {
     return _full_young_gcs;
   }
   void set_full_young_gcs(bool full_young_gcs) {
     _full_young_gcs = full_young_gcs;
   }
   bool adaptive_young_list_length() {
     return _adaptive_young_list_length;
   }
   void set_adaptive_young_list_length(bool adaptive_young_list_length) {
     _adaptive_young_list_length = adaptive_young_list_length;
   }
   inline double get_gc_eff_factor() {
     double ratio = _known_garbage_ratio;
     double square = ratio * ratio;
     // square = square * square;
     double ret = square * 9.0 + 1.0;
 #if 0
     gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
 #endif // 0
     guarantee(0.0 <= ret && ret < 10.0, "invariant!");
     return ret;
   }
   //
   // Survivor regions policy.
   //
 protected:
   // Current tenuring threshold, set to 0 if the collector reaches the
   // maximum amount of suvivors regions.
   int _tenuring_threshold;
   // The limit on the number of regions allocated for survivors.
   size_t _max_survivor_regions;
   // The amount of survor regions after a collection.
   size_t _recorded_survivor_regions;
   // List of survivor regions.
   HeapRegion* _recorded_survivor_head;
   HeapRegion* _recorded_survivor_tail;
   ageTable _survivors_age_table;
 public:
   inline GCAllocPurpose
     evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
       if (age < _tenuring_threshold && src_region->is_young()) {
         return GCAllocForSurvived;
       } else {
         return GCAllocForTenured;
       }
   }
   inline bool track_object_age(GCAllocPurpose purpose) {
     return purpose == GCAllocForSurvived;
   }
   inline GCAllocPurpose alternative_purpose(int purpose) {
     return GCAllocForTenured;
   }
   static const size_t REGIONS_UNLIMITED = ~(size_t)0;
   size_t max_regions(int purpose);
   // The limit on regions for a particular purpose is reached.
   void note_alloc_region_limit_reached(int purpose) {
     if (purpose == GCAllocForSurvived) {
       _tenuring_threshold = 0;
     }
   }
   void note_start_adding_survivor_regions() {
     _survivor_surv_rate_group->start_adding_regions();
   }
   void note_stop_adding_survivor_regions() {
     _survivor_surv_rate_group->stop_adding_regions();
   }
   void record_survivor_regions(size_t      regions,
                                HeapRegion* head,
                                HeapRegion* tail) {
     _recorded_survivor_regions = regions;
     _recorded_survivor_head    = head;
     _recorded_survivor_tail    = tail;
   }
   size_t recorded_survivor_regions() {
     return _recorded_survivor_regions;
   }
   void record_thread_age_table(ageTable* age_table)
   {
     _survivors_age_table.merge_par(age_table);
   }
   // Calculates survivor space parameters.
   void calculate_survivors_policy();
 };
 // This encapsulates a particular strategy for a g1 Collector.
 //
 //      Start a concurrent mark when our heap size is n bytes
 //            greater then our heap size was at the last concurrent
 //            mark.  Where n is a function of the CMSTriggerRatio
 //            and the MinHeapFreeRatio.
 //
 //      Start a g1 collection pause when we have allocated the
 //            average number of bytes currently being freed in
 //            a collection, but only if it is at least one region
 //            full
 //
 //      Resize Heap based on desired
 //      allocation space, where desired allocation space is
 //      a function of survival rate and desired future to size.
 //
 //      Choose collection set by first picking all older regions
 //      which have a survival rate which beats our projected young
 //      survival rate.  Then fill out the number of needed regions
 //      with young regions.
 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
   CollectionSetChooser* _collectionSetChooser;
   // If the estimated is less then desirable, resize if possible.
   void expand_if_possible(size_t numRegions);
   virtual void choose_collection_set(double target_pause_time_ms);
   virtual void record_collection_pause_start(double start_time_sec,
                                              size_t start_used);
   virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
                                                   size_t max_live_bytes);
   virtual void record_full_collection_end();
 public:
   G1CollectorPolicy_BestRegionsFirst() {
     _collectionSetChooser = new CollectionSetChooser();
   }
   void record_collection_pause_end();
   bool should_do_collection_pause(size_t word_size);
   // This is not needed any more, after the CSet choosing code was
   // changed to use the pause prediction work. But let's leave the
   // hook in just in case.
   void note_change_in_marked_bytes(HeapRegion* r) { }
 #ifndef PRODUCT
   bool assertMarkedBytesDataOK();
 #endif
 };
 // This should move to some place more general...
 // If we have "n" measurements, and we've kept track of their "sum" and the
 // "sum_of_squares" of the measurements, this returns the variance of the
 // sequence.
 inline double variance(int n, double sum_of_squares, double sum) {
   double n_d = (double)n;
   double avg = sum/n_d;
   return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
 }
 // Local Variables: ***
 // c-indentation-style: gnu ***
 // End: ***

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp