1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_G1_G1POLICY_HPP
  26 #define SHARE_GC_G1_G1POLICY_HPP
  27 
  28 #include "gc/g1/g1CollectorState.hpp"
  29 #include "gc/g1/g1GCPhaseTimes.hpp"
  30 #include "gc/g1/g1HeapRegionAttr.hpp"
  31 #include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"
  32 #include "gc/g1/g1MMUTracker.hpp"
  33 #include "gc/g1/g1OldGenAllocationTracker.hpp"
  34 #include "gc/g1/g1RemSetTrackingPolicy.hpp"
  35 #include "gc/g1/g1Predictions.hpp"
  36 #include "gc/g1/g1YoungGenSizer.hpp"
  37 #include "gc/shared/gcCause.hpp"
  38 #include "utilities/pair.hpp"
  39 
  40 // A G1Policy makes policy decisions that determine the
  41 // characteristics of the collector.  Examples include:
  42 //   * choice of collection set.
  43 //   * when to collect.
  44 
  45 class HeapRegion;
  46 class G1CollectionSet;
  47 class G1CollectionSetCandidates;
  48 class G1CollectionSetChooser;
  49 class G1IHOPControl;
  50 class G1Analytics;
  51 class G1SurvivorRegions;
  52 class G1YoungGenSizer;
  53 class GCPolicyCounters;
  54 class STWGCTimer;
  55 
  56 class G1Policy: public CHeapObj<mtGC> {
  57  private:
  58 
  59   static G1IHOPControl* create_ihop_control(const G1Predictions* predictor);
  60   // Update the IHOP control with necessary statistics.
  61   void update_ihop_prediction(double mutator_time_s,
  62                               size_t mutator_alloc_bytes,
  63                               size_t young_gen_size,
  64                               bool this_gc_was_young_only);
  65   void report_ihop_statistics();
  66 
  67   G1Predictions _predictor;
  68   G1Analytics* _analytics;
  69   G1RemSetTrackingPolicy _remset_tracker;
  70   G1MMUTracker* _mmu_tracker;
  71   G1IHOPControl* _ihop_control;
  72 
  73   GCPolicyCounters* _policy_counters;
  74 
  75   double _full_collection_start_sec;
  76 
  77   jlong _collection_pause_end_millis;
  78 
  79   uint _young_list_target_length;
  80   uint _young_list_fixed_length;
  81 
  82   // The max number of regions we can extend the eden by while the GC
  83   // locker is active. This should be >= _young_list_target_length;
  84   uint _young_list_max_length;
  85 
  86   // The survivor rate groups below must be initialized after the predictor because they
  87   // indirectly use it through the "this" object passed to their constructor.
  88   G1SurvRateGroup* _eden_surv_rate_group;
  89   G1SurvRateGroup* _survivor_surv_rate_group;
  90 
  91   double _reserve_factor;
  92   // This will be set when the heap is expanded
  93   // for the first time during initialization.
  94   uint   _reserve_regions;
  95 
  96   G1YoungGenSizer* _young_gen_sizer;
  97 
  98   uint _free_regions_at_end_of_collection;
  99 
 100   size_t _rs_length;
 101 
 102   size_t _rs_length_prediction;
 103 
 104   size_t _pending_cards_at_gc_start;
 105 
 106   // Tracking the allocation in the old generation between
 107   // two GCs.
 108   G1OldGenAllocationTracker _old_gen_alloc_tracker;
 109 
 110   G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;
 111 
 112   bool should_update_surv_rate_group_predictors() {
 113     return collector_state()->in_young_only_phase() && !collector_state()->mark_or_rebuild_in_progress();
 114   }
 115 
 116   double logged_cards_processing_time() const;
 117 public:
 118   const G1Predictions& predictor() const { return _predictor; }
 119   const G1Analytics* analytics()   const { return const_cast<const G1Analytics*>(_analytics); }
 120 
 121   G1RemSetTrackingPolicy* remset_tracker() { return &_remset_tracker; }
 122 
 123   G1OldGenAllocationTracker* old_gen_alloc_tracker() { return &_old_gen_alloc_tracker; }
 124 
 125   void set_region_eden(HeapRegion* hr) {
 126     hr->set_eden();
 127     hr->install_surv_rate_group(_eden_surv_rate_group);
 128   }
 129 
 130   void set_region_survivor(HeapRegion* hr) {
 131     assert(hr->is_survivor(), "pre-condition");
 132     hr->install_surv_rate_group(_survivor_surv_rate_group);
 133   }
 134 
 135   void record_rs_length(size_t rs_length) {
 136     _rs_length = rs_length;
 137   }
 138 
 139   double predict_base_elapsed_time_ms(size_t num_pending_cards) const;
 140 
 141 private:
 142   double predict_base_elapsed_time_ms(size_t num_pending_cards, size_t rs_length) const;
 143 
 144   double predict_region_copy_time_ms(HeapRegion* hr) const;
 145 
 146 public:
 147 
 148   double predict_eden_copy_time_ms(uint count, size_t* bytes_to_copy = NULL) const;
 149   double predict_region_non_copy_time_ms(HeapRegion* hr, bool for_young_gc) const;
 150   double predict_region_total_time_ms(HeapRegion* hr, bool for_young_gc) const;
 151 
 152   void cset_regions_freed() {
 153     bool update = should_update_surv_rate_group_predictors();
 154 
 155     _eden_surv_rate_group->all_surviving_words_recorded(predictor(), update);
 156     _survivor_surv_rate_group->all_surviving_words_recorded(predictor(), update);
 157   }
 158 
 159   G1MMUTracker* mmu_tracker() {
 160     return _mmu_tracker;
 161   }
 162 
 163   const G1MMUTracker* mmu_tracker() const {
 164     return _mmu_tracker;
 165   }
 166 
 167   double max_pause_time_ms() const {
 168     return _mmu_tracker->max_gc_time() * 1000.0;
 169   }
 170 
 171 private:
 172   G1CollectionSet* _collection_set;
 173   double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;
 174   double other_time_ms(double pause_time_ms) const;
 175 
 176   double young_other_time_ms() const;
 177   double non_young_other_time_ms() const;
 178   double constant_other_time_ms(double pause_time_ms) const;
 179 
 180   G1CollectionSetChooser* cset_chooser() const;
 181 
 182   // Stash a pointer to the g1 heap.
 183   G1CollectedHeap* _g1h;
 184 
 185   G1GCPhaseTimes* _phase_times;
 186 
 187   // This set of variables tracks the collector efficiency, in order to
 188   // determine whether we should initiate a new marking.
 189   double _mark_remark_start_sec;
 190   double _mark_cleanup_start_sec;
 191 
 192   // Updates the internal young list maximum and target lengths. Returns the
 193   // unbounded young list target length. If no rs_length parameter is passed,
 194   // predict the RS length using the prediction model, otherwise use the
 195   // given rs_length as the prediction.
 196   uint update_young_list_max_and_target_length();
 197   uint update_young_list_max_and_target_length(size_t rs_length);
 198 
 199   // Update the young list target length either by setting it to the
 200   // desired fixed value or by calculating it using G1's pause
 201   // prediction model.
 202   // Returns the unbounded young list target length.
 203   uint update_young_list_target_length(size_t rs_length);
 204 
 205   // Calculate and return the minimum desired young list target
 206   // length. This is the minimum desired young list length according
 207   // to the user's inputs.
 208   uint calculate_young_list_desired_min_length(uint base_min_length) const;
 209 
 210   // Calculate and return the maximum desired young list target
 211   // length. This is the maximum desired young list length according
 212   // to the user's inputs.
 213   uint calculate_young_list_desired_max_length() const;
 214 
 215   // Calculate and return the maximum young list target length that
 216   // can fit into the pause time goal. The parameters are: rs_length
 217   // represent the prediction of how large the young RSet lengths will
 218   // be, base_min_length is the already existing number of regions in
 219   // the young list, min_length and max_length are the desired min and
 220   // max young list length according to the user's inputs.
 221   uint calculate_young_list_target_length(size_t rs_length,
 222                                           uint base_min_length,
 223                                           uint desired_min_length,
 224                                           uint desired_max_length) const;
 225 
 226   // Result of the bounded_young_list_target_length() method, containing both the
 227   // bounded as well as the unbounded young list target lengths in this order.
 228   typedef Pair<uint, uint, StackObj> YoungTargetLengths;
 229   YoungTargetLengths young_list_target_lengths(size_t rs_length) const;
 230 
 231   void update_rs_length_prediction();
 232   void update_rs_length_prediction(size_t prediction);
 233 
 234   size_t predict_bytes_to_copy(HeapRegion* hr) const;
 235   double predict_survivor_regions_evac_time() const;
 236 
 237   // Check whether a given young length (young_length) fits into the
 238   // given target pause time and whether the prediction for the amount
 239   // of objects to be copied for the given length will fit into the
 240   // given free space (expressed by base_free_regions).  It is used by
 241   // calculate_young_list_target_length().
 242   bool predict_will_fit(uint young_length, double base_time_ms,
 243                         uint base_free_regions, double target_pause_time_ms) const;
 244 
 245 public:
 246   size_t pending_cards_at_gc_start() const { return _pending_cards_at_gc_start; }
 247 
 248   // Calculate the minimum number of old regions we'll add to the CSet
 249   // during a mixed GC.
 250   uint calc_min_old_cset_length() const;
 251 
 252   // Calculate the maximum number of old regions we'll add to the CSet
 253   // during a mixed GC.
 254   uint calc_max_old_cset_length() const;
 255 
 256   // Returns the given amount of reclaimable bytes (that represents
 257   // the amount of reclaimable space still to be collected) as a
 258   // percentage of the current heap capacity.
 259   double reclaimable_bytes_percent(size_t reclaimable_bytes) const;
 260 
 261   jlong collection_pause_end_millis() { return _collection_pause_end_millis; }
 262 
 263 private:
 264   void clear_collection_set_candidates();
 265   // Sets up marking if proper conditions are met.
 266   void maybe_start_marking();
 267 
 268   // The kind of STW pause.
 269   enum PauseKind {
 270     FullGC,
 271     YoungOnlyGC,
 272     MixedGC,
 273     LastYoungGC,
 274     InitialMarkGC,
 275     Cleanup,
 276     Remark
 277   };
 278 
 279   // Calculate PauseKind from internal state.
 280   PauseKind young_gc_pause_kind() const;
 281   // Record the given STW pause with the given start and end times (in s).
 282   void record_pause(PauseKind kind, double start, double end);
 283   // Indicate that we aborted marking before doing any mixed GCs.
 284   void abort_time_to_mixed_tracking();
 285 
 286   // Record and log stats before not-full collection.
 287   void record_concurrent_refinement_stats();
 288 
 289 public:
 290 
 291   G1Policy(STWGCTimer* gc_timer);
 292 
 293   virtual ~G1Policy();
 294 
 295   static G1Policy* create_policy(STWGCTimer* gc_timer_stw);
 296 
 297   G1CollectorState* collector_state() const;
 298 
 299   G1GCPhaseTimes* phase_times() const { return _phase_times; }
 300 
 301   // Check the current value of the young list RSet length and
 302   // compare it against the last prediction. If the current value is
 303   // higher, recalculate the young list target length prediction.
 304   void revise_young_list_target_length_if_necessary(size_t rs_length);
 305 
 306   // This should be called after the heap is resized.
 307   void record_new_heap_size(uint new_number_of_regions);
 308 
 309   virtual void init(G1CollectedHeap* g1h, G1CollectionSet* collection_set);
 310 
 311   void note_gc_start();
 312 
 313   bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
 314 
 315   bool about_to_start_mixed_phase() const;
 316 
 317   // Record the start and end of an evacuation pause.
 318   void record_collection_pause_start(double start_time_sec);
 319   virtual void record_collection_pause_end(double pause_time_ms);
 320 
 321   // Record the start and end of a full collection.
 322   void record_full_collection_start();
 323   virtual void record_full_collection_end();
 324 
 325   // Must currently be called while the world is stopped.
 326   void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
 327 
 328   // Record start and end of remark.
 329   void record_concurrent_mark_remark_start();
 330   void record_concurrent_mark_remark_end();
 331 
 332   // Record start, end, and completion of cleanup.
 333   void record_concurrent_mark_cleanup_start();
 334   void record_concurrent_mark_cleanup_end();
 335 
 336   void print_phases();
 337 
 338   bool next_gc_should_be_mixed(const char* true_action_str,
 339                                const char* false_action_str) const;
 340 
 341   // Calculate and return the number of initial and optional old gen regions from
 342   // the given collection set candidates and the remaining time.
 343   void calculate_old_collection_set_regions(G1CollectionSetCandidates* candidates,
 344                                             double time_remaining_ms,
 345                                             uint& num_initial_regions,
 346                                             uint& num_optional_regions);
 347 
 348   // Calculate the number of optional regions from the given collection set candidates,
 349   // the remaining time and the maximum number of these regions and return the number
 350   // of actually selected regions in num_optional_regions.
 351   void calculate_optional_collection_set_regions(G1CollectionSetCandidates* candidates,
 352                                                  uint const max_optional_regions,
 353                                                  double time_remaining_ms,
 354                                                  uint& num_optional_regions);
 355 
 356 private:
 357   // Set the state to start a concurrent marking cycle and clear
 358   // _initiate_conc_mark_if_possible because it has now been
 359   // acted on.
 360   void initiate_conc_mark();
 361 
 362 public:
 363   // This sets the initiate_conc_mark_if_possible() flag to start a
 364   // new cycle, as long as we are not already in one. It's best if it
 365   // is called during a safepoint when the test whether a cycle is in
 366   // progress or not is stable.
 367   bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
 368 
 369   // This is called at the very beginning of an evacuation pause (it
 370   // has to be the first thing that the pause does). If
 371   // initiate_conc_mark_if_possible() is true, and the concurrent
 372   // marking thread has completed its work during the previous cycle,
 373   // it will set in_initial_mark_gc() to so that the pause does
 374   // the initial-mark work and start a marking cycle.
 375   void decide_on_conc_mark_initiation();
 376 
 377   size_t young_list_target_length() const { return _young_list_target_length; }
 378 
 379   bool should_allocate_mutator_region() const;
 380 
 381   bool can_expand_young_list() const;
 382 
 383   uint young_list_max_length() const {
 384     return _young_list_max_length;
 385   }
 386 
 387   bool use_adaptive_young_list_length() const;
 388 
 389   void transfer_survivors_to_cset(const G1SurvivorRegions* survivors);
 390 
 391 private:
 392   //
 393   // Survivor regions policy.
 394   //
 395 
 396   // Current tenuring threshold, set to 0 if the collector reaches the
 397   // maximum amount of survivors regions.
 398   uint _tenuring_threshold;
 399 
 400   // The limit on the number of regions allocated for survivors.
 401   uint _max_survivor_regions;
 402 
 403   AgeTable _survivors_age_table;
 404 
 405   size_t desired_survivor_size(uint max_regions) const;
 406 
 407   // Fraction used when predicting how many optional regions to include in
 408   // the CSet. This fraction of the available time is used for optional regions,
 409   // the rest is used to add old regions to the normal CSet.
 410   double optional_prediction_fraction() { return 0.2; }
 411 
 412 public:
 413   // Fraction used when evacuating the optional regions. This fraction of the
 414   // remaining time is used to choose what regions to include in the evacuation.
 415   double optional_evacuation_fraction() { return 0.75; }
 416 
 417   uint tenuring_threshold() const { return _tenuring_threshold; }
 418 
 419   uint max_survivor_regions() {
 420     return _max_survivor_regions;
 421   }
 422 
 423   void note_start_adding_survivor_regions() {
 424     _survivor_surv_rate_group->start_adding_regions();
 425   }
 426 
 427   void note_stop_adding_survivor_regions() {
 428     _survivor_surv_rate_group->stop_adding_regions();
 429   }
 430 
 431   void record_age_table(AgeTable* age_table) {
 432     _survivors_age_table.merge(age_table);
 433   }
 434 
 435   void print_age_table();
 436 
 437   void update_max_gc_locker_expansion();
 438 
 439   void update_survivors_policy();
 440 
 441   virtual bool force_upgrade_to_full() {
 442     return false;
 443   }
 444 };
 445 
 446 #endif // SHARE_GC_G1_G1POLICY_HPP