1 /* 2 * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 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). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 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 21 * questions. 22 * 23 */ 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/g1ConcurrentStartToMixedTimeTracker.hpp" 30 #include "gc/g1/g1GCPhaseTimes.hpp" 31 #include "gc/g1/g1HeapRegionAttr.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 G1OldGenAllocationTracker* old_gen_alloc_tracker, 60 const G1Predictions* predictor); 61 // Update the IHOP control with necessary statistics. 62 void update_ihop_prediction(double mutator_time_s, 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 72 // Tracking the allocation in the old generation between 73 // two GCs. 74 G1OldGenAllocationTracker _old_gen_alloc_tracker; 75 G1IHOPControl* _ihop_control; 76 77 GCPolicyCounters* _policy_counters; 78 79 double _full_collection_start_sec; 80 81 uint _young_list_target_length; 82 uint _young_list_fixed_length; 83 84 // The max number of regions we can extend the eden by while the GC 85 // locker is active. This should be >= _young_list_target_length; 86 uint _young_list_max_length; 87 88 // The survivor rate groups below must be initialized after the predictor because they 89 // indirectly use it through the "this" object passed to their constructor. 90 G1SurvRateGroup* _eden_surv_rate_group; 91 G1SurvRateGroup* _survivor_surv_rate_group; 92 93 double _reserve_factor; 94 // This will be set when the heap is expanded 95 // for the first time during initialization. 96 uint _reserve_regions; 97 98 G1YoungGenSizer* _young_gen_sizer; 99 100 uint _free_regions_at_end_of_collection; 101 102 size_t _rs_length; 103 104 size_t _rs_length_prediction; 105 106 size_t _pending_cards_at_gc_start; 107 108 G1ConcurrentStartToMixedTimeTracker _concurrent_start_to_mixed; 109 110 bool should_update_surv_rate_group_predictors() { 111 return collector_state()->in_young_only_phase() && !collector_state()->mark_or_rebuild_in_progress(); 112 } 113 114 double logged_cards_processing_time() const; 115 public: 116 const G1Predictions& predictor() const { return _predictor; } 117 const G1Analytics* analytics() const { return const_cast<const G1Analytics*>(_analytics); } 118 119 G1RemSetTrackingPolicy* remset_tracker() { return &_remset_tracker; } 120 121 G1OldGenAllocationTracker* old_gen_alloc_tracker() { return &_old_gen_alloc_tracker; } 122 123 void set_region_eden(HeapRegion* hr) { 124 hr->set_eden(); 125 hr->install_surv_rate_group(_eden_surv_rate_group); 126 } 127 128 void set_region_survivor(HeapRegion* hr) { 129 assert(hr->is_survivor(), "pre-condition"); 130 hr->install_surv_rate_group(_survivor_surv_rate_group); 131 } 132 133 void record_rs_length(size_t rs_length) { 134 _rs_length = rs_length; 135 } 136 137 double predict_base_elapsed_time_ms(size_t num_pending_cards) const; 138 139 private: 140 double predict_base_elapsed_time_ms(size_t num_pending_cards, size_t rs_length) const; 141 142 double predict_region_copy_time_ms(HeapRegion* hr) const; 143 144 public: 145 146 double predict_eden_copy_time_ms(uint count, size_t* bytes_to_copy = NULL) const; 147 double predict_region_non_copy_time_ms(HeapRegion* hr, bool for_young_gc) const; 148 double predict_region_total_time_ms(HeapRegion* hr, bool for_young_gc) const; 149 150 void cset_regions_freed() { 151 bool update = should_update_surv_rate_group_predictors(); 152 153 _eden_surv_rate_group->all_surviving_words_recorded(predictor(), update); 154 _survivor_surv_rate_group->all_surviving_words_recorded(predictor(), update); 155 } 156 157 G1MMUTracker* mmu_tracker() { 158 return _mmu_tracker; 159 } 160 161 const G1MMUTracker* mmu_tracker() const { 162 return _mmu_tracker; 163 } 164 165 double max_pause_time_ms() const { 166 return _mmu_tracker->max_gc_time() * 1000.0; 167 } 168 169 private: 170 G1CollectionSet* _collection_set; 171 double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const; 172 double other_time_ms(double pause_time_ms) const; 173 174 double young_other_time_ms() const; 175 double non_young_other_time_ms() const; 176 double constant_other_time_ms(double pause_time_ms) const; 177 178 G1CollectionSetChooser* cset_chooser() const; 179 180 // Stash a pointer to the g1 heap. 181 G1CollectedHeap* _g1h; 182 183 STWGCTimer* _phase_times_timer; 184 // Lazily initialized 185 mutable 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 private: 262 void clear_collection_set_candidates(); 263 // Sets up marking if proper conditions are met. 264 void maybe_start_marking(); 265 266 // The kind of STW pause. 267 enum PauseKind { 268 FullGC, 269 YoungOnlyGC, 270 MixedGC, 271 LastYoungGC, 272 ConcurrentStartGC, 273 Cleanup, 274 Remark 275 }; 276 277 static bool is_young_only_pause(PauseKind kind); 278 static bool is_mixed_pause(PauseKind kind); 279 static bool is_last_young_pause(PauseKind kind); 280 static bool is_concurrent_start_pause(PauseKind kind); 281 // Calculate PauseKind from internal state. 282 PauseKind young_gc_pause_kind() const; 283 // Record the given STW pause with the given start and end times (in s). 284 void record_pause(PauseKind kind, double start, double end); 285 // Indicate that we aborted marking before doing any mixed GCs. 286 void abort_time_to_mixed_tracking(); 287 288 // Record and log stats before not-full collection. 289 void record_concurrent_refinement_stats(); 290 291 public: 292 293 G1Policy(STWGCTimer* gc_timer); 294 295 virtual ~G1Policy(); 296 297 static G1Policy* create_policy(STWGCTimer* gc_timer_stw); 298 299 G1CollectorState* collector_state() const; 300 301 G1GCPhaseTimes* phase_times() const; 302 303 // Check the current value of the young list RSet length and 304 // compare it against the last prediction. If the current value is 305 // higher, recalculate the young list target length prediction. 306 void revise_young_list_target_length_if_necessary(size_t rs_length); 307 308 // This should be called after the heap is resized. 309 void record_new_heap_size(uint new_number_of_regions); 310 311 virtual void init(G1CollectedHeap* g1h, G1CollectionSet* collection_set); 312 313 void note_gc_start(); 314 315 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 316 317 bool about_to_start_mixed_phase() const; 318 319 // Record the start and end of an evacuation pause. 320 void record_collection_pause_start(double start_time_sec); 321 virtual void record_collection_pause_end(double pause_time_ms); 322 323 // Record the start and end of a full collection. 324 void record_full_collection_start(); 325 virtual void record_full_collection_end(); 326 327 // Must currently be called while the world is stopped. 328 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms); 329 330 // Record start and end of remark. 331 void record_concurrent_mark_remark_start(); 332 void record_concurrent_mark_remark_end(); 333 334 // Record start, end, and completion of cleanup. 335 void record_concurrent_mark_cleanup_start(); 336 void record_concurrent_mark_cleanup_end(); 337 338 void print_phases(); 339 340 bool next_gc_should_be_mixed(const char* true_action_str, 341 const char* false_action_str) const; 342 343 // Calculate and return the number of initial and optional old gen regions from 344 // the given collection set candidates and the remaining time. 345 void calculate_old_collection_set_regions(G1CollectionSetCandidates* candidates, 346 double time_remaining_ms, 347 uint& num_initial_regions, 348 uint& num_optional_regions); 349 350 // Calculate the number of optional regions from the given collection set candidates, 351 // the remaining time and the maximum number of these regions and return the number 352 // of actually selected regions in num_optional_regions. 353 void calculate_optional_collection_set_regions(G1CollectionSetCandidates* candidates, 354 uint const max_optional_regions, 355 double time_remaining_ms, 356 uint& num_optional_regions); 357 358 private: 359 // Set the state to start a concurrent marking cycle and clear 360 // _initiate_conc_mark_if_possible because it has now been 361 // acted on. 362 void initiate_conc_mark(); 363 364 public: 365 // This sets the initiate_conc_mark_if_possible() flag to start a 366 // new cycle, as long as we are not already in one. It's best if it 367 // is called during a safepoint when the test whether a cycle is in 368 // progress or not is stable. 369 bool force_concurrent_start_if_outside_cycle(GCCause::Cause gc_cause); 370 371 // This is called at the very beginning of an evacuation pause (it 372 // has to be the first thing that the pause does). If 373 // initiate_conc_mark_if_possible() is true, and the concurrent 374 // marking thread has completed its work during the previous cycle, 375 // it will set in_concurrent_start_gc() to so that the pause does 376 // the concurrent start work and start a marking cycle. 377 void decide_on_conc_mark_initiation(); 378 379 size_t young_list_target_length() const { return _young_list_target_length; } 380 381 bool should_allocate_mutator_region() const; 382 383 bool can_expand_young_list() const; 384 385 uint young_list_max_length() const { 386 return _young_list_max_length; 387 } 388 389 bool use_adaptive_young_list_length() const; 390 391 void transfer_survivors_to_cset(const G1SurvivorRegions* survivors); 392 393 private: 394 // 395 // Survivor regions policy. 396 // 397 398 // Current tenuring threshold, set to 0 if the collector reaches the 399 // maximum amount of survivors regions. 400 uint _tenuring_threshold; 401 402 // The limit on the number of regions allocated for survivors. 403 uint _max_survivor_regions; 404 405 AgeTable _survivors_age_table; 406 407 size_t desired_survivor_size(uint max_regions) const; 408 409 // Fraction used when predicting how many optional regions to include in 410 // the CSet. This fraction of the available time is used for optional regions, 411 // the rest is used to add old regions to the normal CSet. 412 double optional_prediction_fraction() { return 0.2; } 413 414 public: 415 // Fraction used when evacuating the optional regions. This fraction of the 416 // remaining time is used to choose what regions to include in the evacuation. 417 double optional_evacuation_fraction() { return 0.75; } 418 419 uint tenuring_threshold() const { return _tenuring_threshold; } 420 421 uint max_survivor_regions() { 422 return _max_survivor_regions; 423 } 424 425 void note_start_adding_survivor_regions() { 426 _survivor_surv_rate_group->start_adding_regions(); 427 } 428 429 void note_stop_adding_survivor_regions() { 430 _survivor_surv_rate_group->stop_adding_regions(); 431 } 432 433 void record_age_table(AgeTable* age_table) { 434 _survivors_age_table.merge(age_table); 435 } 436 437 void print_age_table(); 438 439 void update_max_gc_locker_expansion(); 440 441 void update_survivors_policy(); 442 443 virtual bool force_upgrade_to_full() { 444 return false; 445 } 446 }; 447 448 #endif // SHARE_GC_G1_G1POLICY_HPP