1 /* 2 * Copyright (c) 2001, 2019, 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_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP 27 28 #include "gc_implementation/g1/collectionSetChooser.hpp" 29 #include "gc_implementation/g1/g1Allocator.hpp" 30 #include "gc_implementation/g1/g1MMUTracker.hpp" 31 #include "gc_implementation/g1/g1IHOPControl.hpp" 32 #include "memory/collectorPolicy.hpp" 33 34 // A G1CollectorPolicy makes policy decisions that determine the 35 // characteristics of the collector. Examples include: 36 // * choice of collection set. 37 // * when to collect. 38 39 class HeapRegion; 40 class CollectionSetChooser; 41 class G1GCPhaseTimes; 42 43 // TraceGen0Time collects data on _both_ young and mixed evacuation pauses 44 // (the latter may contain non-young regions - i.e. regions that are 45 // technically in Gen1) while TraceGen1Time collects data about full GCs. 46 class TraceGen0TimeData : public CHeapObj<mtGC> { 47 private: 48 unsigned _young_pause_num; 49 unsigned _mixed_pause_num; 50 51 NumberSeq _all_stop_world_times_ms; 52 NumberSeq _all_yield_times_ms; 53 54 NumberSeq _total; 55 NumberSeq _other; 56 NumberSeq _root_region_scan_wait; 57 NumberSeq _parallel; 58 NumberSeq _ext_root_scan; 59 NumberSeq _satb_filtering; 60 NumberSeq _update_rs; 61 NumberSeq _scan_rs; 62 NumberSeq _obj_copy; 63 NumberSeq _termination; 64 NumberSeq _parallel_other; 65 NumberSeq _clear_ct; 66 67 void print_summary(const char* str, const NumberSeq* seq) const; 68 void print_summary_sd(const char* str, const NumberSeq* seq) const; 69 70 public: 71 TraceGen0TimeData() : _young_pause_num(0), _mixed_pause_num(0) {}; 72 void record_start_collection(double time_to_stop_the_world_ms); 73 void record_yield_time(double yield_time_ms); 74 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times); 75 void increment_young_collection_count(); 76 void increment_mixed_collection_count(); 77 void print() const; 78 }; 79 80 class TraceGen1TimeData : public CHeapObj<mtGC> { 81 private: 82 NumberSeq _all_full_gc_times; 83 84 public: 85 void record_full_collection(double full_gc_time_ms); 86 void print() const; 87 }; 88 89 // There are three command line options related to the young gen size: 90 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is 91 // just a short form for NewSize==MaxNewSize). G1 will use its internal 92 // heuristics to calculate the actual young gen size, so these options 93 // basically only limit the range within which G1 can pick a young gen 94 // size. Also, these are general options taking byte sizes. G1 will 95 // internally work with a number of regions instead. So, some rounding 96 // will occur. 97 // 98 // If nothing related to the the young gen size is set on the command 99 // line we should allow the young gen to be between G1NewSizePercent 100 // and G1MaxNewSizePercent of the heap size. This means that every time 101 // the heap size changes, the limits for the young gen size will be 102 // recalculated. 103 // 104 // If only -XX:NewSize is set we should use the specified value as the 105 // minimum size for young gen. Still using G1MaxNewSizePercent of the 106 // heap as maximum. 107 // 108 // If only -XX:MaxNewSize is set we should use the specified value as the 109 // maximum size for young gen. Still using G1NewSizePercent of the heap 110 // as minimum. 111 // 112 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values. 113 // No updates when the heap size changes. There is a special case when 114 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a 115 // different heuristic for calculating the collection set when we do mixed 116 // collection. 117 // 118 // If only -XX:NewRatio is set we should use the specified ratio of the heap 119 // as both min and max. This will be interpreted as "fixed" just like the 120 // NewSize==MaxNewSize case above. But we will update the min and max 121 // everytime the heap size changes. 122 // 123 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is 124 // combined with either NewSize or MaxNewSize. (A warning message is printed.) 125 class G1YoungGenSizer : public CHeapObj<mtGC> { 126 private: 127 enum SizerKind { 128 SizerDefaults, 129 SizerNewSizeOnly, 130 SizerMaxNewSizeOnly, 131 SizerMaxAndNewSize, 132 SizerNewRatio 133 }; 134 SizerKind _sizer_kind; 135 uint _min_desired_young_length; 136 uint _max_desired_young_length; 137 bool _adaptive_size; 138 uint calculate_default_min_length(uint new_number_of_heap_regions); 139 uint calculate_default_max_length(uint new_number_of_heap_regions); 140 141 // Update the given values for minimum and maximum young gen length in regions 142 // given the number of heap regions depending on the kind of sizing algorithm. 143 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length); 144 145 public: 146 G1YoungGenSizer(); 147 // Calculate the maximum length of the young gen given the number of regions 148 // depending on the sizing algorithm. 149 uint max_young_length(uint number_of_heap_regions); 150 151 void heap_size_changed(uint new_number_of_heap_regions); 152 uint min_desired_young_length() { 153 return _min_desired_young_length; 154 } 155 uint max_desired_young_length() { 156 return _max_desired_young_length; 157 } 158 bool adaptive_young_list_length() { 159 return _adaptive_size; 160 } 161 }; 162 163 class G1CollectorPolicy: public CollectorPolicy { 164 private: 165 static G1IHOPControl* create_ihop_control(); 166 167 // either equal to the number of parallel threads, if ParallelGCThreads 168 // has been set, or 1 otherwise 169 int _parallel_gc_threads; 170 171 // The number of GC threads currently active. 172 uintx _no_of_gc_threads; 173 174 enum SomePrivateConstants { 175 NumPrevPausesForHeuristics = 10 176 }; 177 178 G1MMUTracker* _mmu_tracker; 179 G1IHOPControl* _ihop_control; 180 181 void initialize_alignments(); 182 void initialize_flags(); 183 184 CollectionSetChooser* _collectionSetChooser; 185 186 double _full_collection_start_sec; 187 uint _cur_collection_pause_used_regions_at_start; 188 189 // These exclude marking times. 190 TruncatedSeq* _recent_gc_times_ms; 191 192 TruncatedSeq* _concurrent_mark_remark_times_ms; 193 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 194 195 TraceGen0TimeData _trace_gen0_time_data; 196 TraceGen1TimeData _trace_gen1_time_data; 197 198 double _stop_world_start; 199 200 // indicates whether we are in young or mixed GC mode 201 bool _gcs_are_young; 202 203 uint _young_list_target_length; 204 uint _young_list_fixed_length; 205 206 // The max number of regions we can extend the eden by while the GC 207 // locker is active. This should be >= _young_list_target_length; 208 uint _young_list_max_length; 209 210 bool _last_gc_was_young; 211 212 bool _during_marking; 213 bool _in_marking_window; 214 bool _in_marking_window_im; 215 216 SurvRateGroup* _short_lived_surv_rate_group; 217 SurvRateGroup* _survivor_surv_rate_group; 218 // add here any more surv rate groups 219 220 double _gc_overhead_perc; 221 222 double _reserve_factor; 223 uint _reserve_regions; 224 225 bool during_marking() { 226 return _during_marking; 227 } 228 229 enum PredictionConstants { 230 TruncatedSeqLength = 10 231 }; 232 233 TruncatedSeq* _alloc_rate_ms_seq; 234 double _prev_collection_pause_end_ms; 235 236 TruncatedSeq* _rs_length_diff_seq; 237 TruncatedSeq* _cost_per_card_ms_seq; 238 TruncatedSeq* _young_cards_per_entry_ratio_seq; 239 TruncatedSeq* _mixed_cards_per_entry_ratio_seq; 240 TruncatedSeq* _cost_per_entry_ms_seq; 241 TruncatedSeq* _mixed_cost_per_entry_ms_seq; 242 TruncatedSeq* _cost_per_byte_ms_seq; 243 TruncatedSeq* _constant_other_time_ms_seq; 244 TruncatedSeq* _young_other_cost_per_region_ms_seq; 245 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 246 247 TruncatedSeq* _pending_cards_seq; 248 TruncatedSeq* _rs_lengths_seq; 249 250 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 251 252 G1YoungGenSizer* _young_gen_sizer; 253 254 uint _eden_cset_region_length; 255 uint _survivor_cset_region_length; 256 uint _old_cset_region_length; 257 258 void init_cset_region_lengths(uint eden_cset_region_length, 259 uint survivor_cset_region_length); 260 261 uint eden_cset_region_length() { return _eden_cset_region_length; } 262 uint survivor_cset_region_length() { return _survivor_cset_region_length; } 263 uint old_cset_region_length() { return _old_cset_region_length; } 264 265 uint _free_regions_at_end_of_collection; 266 267 size_t _recorded_rs_lengths; 268 size_t _max_rs_lengths; 269 double _sigma; 270 271 size_t _rs_lengths_prediction; 272 273 double sigma() { return _sigma; } 274 275 // A function that prevents us putting too much stock in small sample 276 // sets. Returns a number between 2.0 and 1.0, depending on the number 277 // of samples. 5 or more samples yields one; fewer scales linearly from 278 // 2.0 at 1 sample to 1.0 at 5. 279 double confidence_factor(int samples) { 280 if (samples > 4) return 1.0; 281 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 282 } 283 284 double get_new_neg_prediction(TruncatedSeq* seq) { 285 return seq->davg() - sigma() * seq->dsd(); 286 } 287 288 #ifndef PRODUCT 289 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 290 #endif // PRODUCT 291 292 void adjust_concurrent_refinement(double update_rs_time, 293 double update_rs_processed_buffers, 294 double goal_ms); 295 296 uintx no_of_gc_threads() { return _no_of_gc_threads; } 297 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; } 298 299 double _pause_time_target_ms; 300 301 size_t _pending_cards; 302 303 public: 304 // Accessors 305 306 void set_region_eden(HeapRegion* hr, int young_index_in_cset) { 307 hr->set_eden(); 308 hr->install_surv_rate_group(_short_lived_surv_rate_group); 309 hr->set_young_index_in_cset(young_index_in_cset); 310 } 311 312 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) { 313 assert(hr->is_survivor(), "pre-condition"); 314 hr->install_surv_rate_group(_survivor_surv_rate_group); 315 hr->set_young_index_in_cset(young_index_in_cset); 316 } 317 318 #ifndef PRODUCT 319 bool verify_young_ages(); 320 #endif // PRODUCT 321 322 double get_new_prediction(TruncatedSeq* seq) { 323 return MAX2(seq->davg() + sigma() * seq->dsd(), 324 seq->davg() * confidence_factor(seq->num())); 325 } 326 327 void record_max_rs_lengths(size_t rs_lengths) { 328 _max_rs_lengths = rs_lengths; 329 } 330 331 size_t predict_rs_length_diff() { 332 return (size_t) get_new_prediction(_rs_length_diff_seq); 333 } 334 335 double predict_alloc_rate_ms() { 336 return get_new_prediction(_alloc_rate_ms_seq); 337 } 338 339 double predict_cost_per_card_ms() { 340 return get_new_prediction(_cost_per_card_ms_seq); 341 } 342 343 double predict_rs_update_time_ms(size_t pending_cards) { 344 return (double) pending_cards * predict_cost_per_card_ms(); 345 } 346 347 double predict_young_cards_per_entry_ratio() { 348 return get_new_prediction(_young_cards_per_entry_ratio_seq); 349 } 350 351 double predict_mixed_cards_per_entry_ratio() { 352 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 353 return predict_young_cards_per_entry_ratio(); 354 } else { 355 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 356 } 357 } 358 359 size_t predict_young_card_num(size_t rs_length) { 360 return (size_t) ((double) rs_length * 361 predict_young_cards_per_entry_ratio()); 362 } 363 364 size_t predict_non_young_card_num(size_t rs_length) { 365 return (size_t) ((double) rs_length * 366 predict_mixed_cards_per_entry_ratio()); 367 } 368 369 double predict_rs_scan_time_ms(size_t card_num) { 370 if (gcs_are_young()) { 371 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 372 } else { 373 return predict_mixed_rs_scan_time_ms(card_num); 374 } 375 } 376 377 double predict_mixed_rs_scan_time_ms(size_t card_num) { 378 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 379 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 380 } else { 381 return (double) (card_num * 382 get_new_prediction(_mixed_cost_per_entry_ms_seq)); 383 } 384 } 385 386 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 387 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 388 return (1.1 * (double) bytes_to_copy) * 389 get_new_prediction(_cost_per_byte_ms_seq); 390 } else { 391 return (double) bytes_to_copy * 392 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 393 } 394 } 395 396 double predict_object_copy_time_ms(size_t bytes_to_copy) { 397 if (_in_marking_window && !_in_marking_window_im) { 398 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 399 } else { 400 return (double) bytes_to_copy * 401 get_new_prediction(_cost_per_byte_ms_seq); 402 } 403 } 404 405 double predict_constant_other_time_ms() { 406 return get_new_prediction(_constant_other_time_ms_seq); 407 } 408 409 double predict_young_other_time_ms(size_t young_num) { 410 return (double) young_num * 411 get_new_prediction(_young_other_cost_per_region_ms_seq); 412 } 413 414 double predict_non_young_other_time_ms(size_t non_young_num) { 415 return (double) non_young_num * 416 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 417 } 418 419 double predict_base_elapsed_time_ms(size_t pending_cards); 420 double predict_base_elapsed_time_ms(size_t pending_cards, 421 size_t scanned_cards); 422 size_t predict_bytes_to_copy(HeapRegion* hr); 423 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc); 424 425 void set_recorded_rs_lengths(size_t rs_lengths); 426 427 uint cset_region_length() { return young_cset_region_length() + 428 old_cset_region_length(); } 429 uint young_cset_region_length() { return eden_cset_region_length() + 430 survivor_cset_region_length(); } 431 432 double predict_survivor_regions_evac_time(); 433 434 void cset_regions_freed() { 435 bool propagate = _last_gc_was_young && !_in_marking_window; 436 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 437 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 438 // also call it on any more surv rate groups 439 } 440 441 G1MMUTracker* mmu_tracker() { 442 return _mmu_tracker; 443 } 444 445 double max_pause_time_ms() { 446 return _mmu_tracker->max_gc_time() * 1000.0; 447 } 448 449 double predict_remark_time_ms() { 450 return get_new_prediction(_concurrent_mark_remark_times_ms); 451 } 452 453 double predict_cleanup_time_ms() { 454 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 455 } 456 457 // Returns an estimate of the survival rate of the region at yg-age 458 // "yg_age". 459 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 460 TruncatedSeq* seq = surv_rate_group->get_seq(age); 461 if (seq->num() == 0) 462 gclog_or_tty->print("BARF! age is %d", age); 463 guarantee( seq->num() > 0, "invariant" ); 464 double pred = get_new_prediction(seq); 465 if (pred > 1.0) 466 pred = 1.0; 467 return pred; 468 } 469 470 double predict_yg_surv_rate(int age) { 471 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 472 } 473 474 double accum_yg_surv_rate_pred(int age) { 475 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 476 } 477 478 private: 479 // Statistics kept per GC stoppage, pause or full. 480 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 481 482 // Add a new GC of the given duration and end time to the record. 483 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 484 485 // The head of the list (via "next_in_collection_set()") representing the 486 // current collection set. Set from the incrementally built collection 487 // set at the start of the pause. 488 HeapRegion* _collection_set; 489 490 // The number of bytes in the collection set before the pause. Set from 491 // the incrementally built collection set at the start of an evacuation 492 // pause, and incremented in finalize_cset() when adding old regions 493 // (if any) to the collection set. 494 size_t _collection_set_bytes_used_before; 495 496 // The number of bytes copied during the GC. 497 size_t _bytes_copied_during_gc; 498 499 // The associated information that is maintained while the incremental 500 // collection set is being built with young regions. Used to populate 501 // the recorded info for the evacuation pause. 502 503 enum CSetBuildType { 504 Active, // We are actively building the collection set 505 Inactive // We are not actively building the collection set 506 }; 507 508 CSetBuildType _inc_cset_build_state; 509 510 // The head of the incrementally built collection set. 511 HeapRegion* _inc_cset_head; 512 513 // The tail of the incrementally built collection set. 514 HeapRegion* _inc_cset_tail; 515 516 // The number of bytes in the incrementally built collection set. 517 // Used to set _collection_set_bytes_used_before at the start of 518 // an evacuation pause. 519 size_t _inc_cset_bytes_used_before; 520 521 // Used to record the highest end of heap region in collection set 522 HeapWord* _inc_cset_max_finger; 523 524 // The RSet lengths recorded for regions in the CSet. It is updated 525 // by the thread that adds a new region to the CSet. We assume that 526 // only one thread can be allocating a new CSet region (currently, 527 // it does so after taking the Heap_lock) hence no need to 528 // synchronize updates to this field. 529 size_t _inc_cset_recorded_rs_lengths; 530 531 // A concurrent refinement thread periodcially samples the young 532 // region RSets and needs to update _inc_cset_recorded_rs_lengths as 533 // the RSets grow. Instead of having to syncronize updates to that 534 // field we accumulate them in this field and add it to 535 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC. 536 ssize_t _inc_cset_recorded_rs_lengths_diffs; 537 538 // The predicted elapsed time it will take to collect the regions in 539 // the CSet. This is updated by the thread that adds a new region to 540 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about 541 // MT-safety assumptions. 542 double _inc_cset_predicted_elapsed_time_ms; 543 544 // See the comment for _inc_cset_recorded_rs_lengths_diffs. 545 double _inc_cset_predicted_elapsed_time_ms_diffs; 546 547 // Stash a pointer to the g1 heap. 548 G1CollectedHeap* _g1; 549 550 G1GCPhaseTimes* _phase_times; 551 552 // The ratio of gc time to elapsed time, computed over recent pauses. 553 double _recent_avg_pause_time_ratio; 554 555 double recent_avg_pause_time_ratio() { 556 return _recent_avg_pause_time_ratio; 557 } 558 559 // At the end of a pause we check the heap occupancy and we decide 560 // whether we will start a marking cycle during the next pause. If 561 // we decide that we want to do that, we will set this parameter to 562 // true. So, this parameter will stay true between the end of a 563 // pause and the beginning of a subsequent pause (not necessarily 564 // the next one, see the comments on the next field) when we decide 565 // that we will indeed start a marking cycle and do the initial-mark 566 // work. 567 volatile bool _initiate_conc_mark_if_possible; 568 569 // If initiate_conc_mark_if_possible() is set at the beginning of a 570 // pause, it is a suggestion that the pause should start a marking 571 // cycle by doing the initial-mark work. However, it is possible 572 // that the concurrent marking thread is still finishing up the 573 // previous marking cycle (e.g., clearing the next marking 574 // bitmap). If that is the case we cannot start a new cycle and 575 // we'll have to wait for the concurrent marking thread to finish 576 // what it is doing. In this case we will postpone the marking cycle 577 // initiation decision for the next pause. When we eventually decide 578 // to start a cycle, we will set _during_initial_mark_pause which 579 // will stay true until the end of the initial-mark pause and it's 580 // the condition that indicates that a pause is doing the 581 // initial-mark work. 582 volatile bool _during_initial_mark_pause; 583 584 bool _last_young_gc; 585 586 // This set of variables tracks the collector efficiency, in order to 587 // determine whether we should initiate a new marking. 588 double _cur_mark_stop_world_time_ms; 589 double _mark_remark_start_sec; 590 double _mark_cleanup_start_sec; 591 592 // Update the young list target length either by setting it to the 593 // desired fixed value or by calculating it using G1's pause 594 // prediction model. If no rs_lengths parameter is passed, predict 595 // the RS lengths using the prediction model, otherwise use the 596 // given rs_lengths as the prediction. 597 void update_young_list_target_length(size_t rs_lengths = (size_t) -1); 598 599 // Calculate and return the minimum desired young list target 600 // length. This is the minimum desired young list length according 601 // to the user's inputs. 602 uint calculate_young_list_desired_min_length(uint base_min_length); 603 604 // Calculate and return the maximum desired young list target 605 // length. This is the maximum desired young list length according 606 // to the user's inputs. 607 uint calculate_young_list_desired_max_length(); 608 609 // Calculate and return the maximum young list target length that 610 // can fit into the pause time goal. The parameters are: rs_lengths 611 // represent the prediction of how large the young RSet lengths will 612 // be, base_min_length is the alreay existing number of regions in 613 // the young list, min_length and max_length are the desired min and 614 // max young list length according to the user's inputs. 615 uint calculate_young_list_target_length(size_t rs_lengths, 616 uint base_min_length, 617 uint desired_min_length, 618 uint desired_max_length); 619 620 // Check whether a given young length (young_length) fits into the 621 // given target pause time and whether the prediction for the amount 622 // of objects to be copied for the given length will fit into the 623 // given free space (expressed by base_free_regions). It is used by 624 // calculate_young_list_target_length(). 625 bool predict_will_fit(uint young_length, double base_time_ms, 626 uint base_free_regions, double target_pause_time_ms); 627 628 // Calculate the minimum number of old regions we'll add to the CSet 629 // during a mixed GC. 630 uint calc_min_old_cset_length(); 631 632 // Calculate the maximum number of old regions we'll add to the CSet 633 // during a mixed GC. 634 uint calc_max_old_cset_length(); 635 636 // Returns the given amount of uncollected reclaimable space 637 // as a percentage of the current heap capacity. 638 double reclaimable_bytes_perc(size_t reclaimable_bytes); 639 640 public: 641 642 G1CollectorPolicy(); 643 virtual ~G1CollectorPolicy(); 644 645 virtual G1CollectorPolicy* as_g1_policy() { return this; } 646 647 virtual CollectorPolicy::Name kind() { 648 return CollectorPolicy::G1CollectorPolicyKind; 649 } 650 651 G1GCPhaseTimes* phase_times() const { return _phase_times; } 652 653 // Check the current value of the young list RSet lengths and 654 // compare it against the last prediction. If the current value is 655 // higher, recalculate the young list target length prediction. 656 void revise_young_list_target_length_if_necessary(); 657 658 // This should be called after the heap is resized. 659 void record_new_heap_size(uint new_number_of_regions); 660 661 void init(); 662 663 // Create jstat counters for the policy. 664 virtual void initialize_gc_policy_counters(); 665 666 virtual HeapWord* mem_allocate_work(size_t size, 667 bool is_tlab, 668 bool* gc_overhead_limit_was_exceeded); 669 670 // This method controls how a collector handles one or more 671 // of its generations being fully allocated. 672 virtual HeapWord* satisfy_failed_allocation(size_t size, 673 bool is_tlab); 674 675 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 676 677 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 678 679 // Record the start and end of an evacuation pause. 680 void record_collection_pause_start(double start_time_sec); 681 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info); 682 683 // Record the start and end of a full collection. 684 void record_full_collection_start(); 685 void record_full_collection_end(); 686 687 // Must currently be called while the world is stopped. 688 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms); 689 690 // Record start and end of remark. 691 void record_concurrent_mark_remark_start(); 692 void record_concurrent_mark_remark_end(); 693 694 // Record start, end, and completion of cleanup. 695 void record_concurrent_mark_cleanup_start(); 696 void record_concurrent_mark_cleanup_end(int no_of_gc_threads); 697 void record_concurrent_mark_cleanup_completed(); 698 699 // Records the information about the heap size for reporting in 700 // print_detailed_heap_transition 701 void record_heap_size_info_at_start(bool full); 702 703 // Print heap sizing transition (with less and more detail). 704 void print_heap_transition(); 705 void print_detailed_heap_transition(bool full = false); 706 707 void record_stop_world_start(); 708 void record_concurrent_pause(); 709 710 // Record how much space we copied during a GC. This is typically 711 // called when a GC alloc region is being retired. 712 void record_bytes_copied_during_gc(size_t bytes) { 713 _bytes_copied_during_gc += bytes; 714 } 715 716 // The amount of space we copied during a GC. 717 size_t bytes_copied_during_gc() { 718 return _bytes_copied_during_gc; 719 } 720 721 // Determine whether there are candidate regions so that the 722 // next GC should be mixed. The two action strings are used 723 // in the ergo output when the method returns true or false. 724 bool next_gc_should_be_mixed(const char* true_action_str, 725 const char* false_action_str); 726 727 // Choose a new collection set. Marks the chosen regions as being 728 // "in_collection_set", and links them together. The head and number of 729 // the collection set are available via access methods. 730 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info); 731 732 // The head of the list (via "next_in_collection_set()") representing the 733 // current collection set. 734 HeapRegion* collection_set() { return _collection_set; } 735 736 void clear_collection_set() { _collection_set = NULL; } 737 738 // Add old region "hr" to the CSet. 739 void add_old_region_to_cset(HeapRegion* hr); 740 741 // Incremental CSet Support 742 743 // The head of the incrementally built collection set. 744 HeapRegion* inc_cset_head() { return _inc_cset_head; } 745 746 // The tail of the incrementally built collection set. 747 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 748 749 // Initialize incremental collection set info. 750 void start_incremental_cset_building(); 751 752 // Perform any final calculations on the incremental CSet fields 753 // before we can use them. 754 void finalize_incremental_cset_building(); 755 756 void clear_incremental_cset() { 757 _inc_cset_head = NULL; 758 _inc_cset_tail = NULL; 759 } 760 761 // Stop adding regions to the incremental collection set 762 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 763 764 // Add information about hr to the aggregated information for the 765 // incrementally built collection set. 766 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 767 768 // Update information about hr in the aggregated information for 769 // the incrementally built collection set. 770 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 771 772 private: 773 // Update the incremental cset information when adding a region 774 // (should not be called directly). 775 void add_region_to_incremental_cset_common(HeapRegion* hr); 776 777 public: 778 // Add hr to the LHS of the incremental collection set. 779 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 780 781 // Add hr to the RHS of the incremental collection set. 782 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 783 784 #ifndef PRODUCT 785 void print_collection_set(HeapRegion* list_head, outputStream* st); 786 #endif // !PRODUCT 787 788 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 789 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 790 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 791 792 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 793 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 794 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 795 796 // This sets the initiate_conc_mark_if_possible() flag to start a 797 // new cycle, as long as we are not already in one. It's best if it 798 // is called during a safepoint when the test whether a cycle is in 799 // progress or not is stable. 800 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause); 801 802 // This is called at the very beginning of an evacuation pause (it 803 // has to be the first thing that the pause does). If 804 // initiate_conc_mark_if_possible() is true, and the concurrent 805 // marking thread has completed its work during the previous cycle, 806 // it will set during_initial_mark_pause() to so that the pause does 807 // the initial-mark work and start a marking cycle. 808 void decide_on_conc_mark_initiation(); 809 810 // If an expansion would be appropriate, because recent GC overhead had 811 // exceeded the desired limit, return an amount to expand by. 812 virtual size_t expansion_amount(); 813 814 // Print tracing information. 815 void print_tracing_info() const; 816 817 // Print stats on young survival ratio 818 void print_yg_surv_rate_info() const; 819 820 void finished_recalculating_age_indexes(bool is_survivors) { 821 if (is_survivors) { 822 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 823 } else { 824 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 825 } 826 // do that for any other surv rate groups 827 } 828 829 size_t young_list_target_length() const { return _young_list_target_length; } 830 831 bool is_young_list_full(); 832 833 bool can_expand_young_list(); 834 835 uint young_list_max_length() { 836 return _young_list_max_length; 837 } 838 839 bool gcs_are_young() { 840 return _gcs_are_young; 841 } 842 void set_gcs_are_young(bool gcs_are_young) { 843 _gcs_are_young = gcs_are_young; 844 } 845 846 bool adaptive_young_list_length() { 847 return _young_gen_sizer->adaptive_young_list_length(); 848 } 849 850 private: 851 // 852 // Survivor regions policy. 853 // 854 855 // Current tenuring threshold, set to 0 if the collector reaches the 856 // maximum amount of survivors regions. 857 uint _tenuring_threshold; 858 859 // The limit on the number of regions allocated for survivors. 860 uint _max_survivor_regions; 861 862 // For reporting purposes. 863 // The value of _heap_bytes_before_gc is also used to calculate 864 // the cost of copying. 865 866 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC 867 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC 868 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC 869 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC 870 871 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC 872 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC 873 874 // The amount of survivor regions after a collection. 875 uint _recorded_survivor_regions; 876 // List of survivor regions. 877 HeapRegion* _recorded_survivor_head; 878 HeapRegion* _recorded_survivor_tail; 879 880 ageTable _survivors_age_table; 881 882 public: 883 uint tenuring_threshold() const { return _tenuring_threshold; } 884 885 static const uint REGIONS_UNLIMITED = (uint) -1; 886 887 uint max_regions(InCSetState dest) { 888 switch (dest.value()) { 889 case InCSetState::Young: 890 return _max_survivor_regions; 891 case InCSetState::Old: 892 return REGIONS_UNLIMITED; 893 default: 894 assert(false, err_msg("Unknown dest state: " CSETSTATE_FORMAT, dest.value())); 895 break; 896 } 897 // keep some compilers happy 898 return 0; 899 } 900 901 void note_start_adding_survivor_regions() { 902 _survivor_surv_rate_group->start_adding_regions(); 903 } 904 905 void note_stop_adding_survivor_regions() { 906 _survivor_surv_rate_group->stop_adding_regions(); 907 } 908 909 void record_survivor_regions(uint regions, 910 HeapRegion* head, 911 HeapRegion* tail) { 912 _recorded_survivor_regions = regions; 913 _recorded_survivor_head = head; 914 _recorded_survivor_tail = tail; 915 } 916 917 uint recorded_survivor_regions() { 918 return _recorded_survivor_regions; 919 } 920 921 void record_thread_age_table(ageTable* age_table) { 922 _survivors_age_table.merge_par(age_table); 923 } 924 925 void update_max_gc_locker_expansion(); 926 927 // Calculates survivor space parameters. 928 void update_survivors_policy(); 929 930 virtual void post_heap_initialize(); 931 }; 932 933 // This should move to some place more general... 934 935 // If we have "n" measurements, and we've kept track of their "sum" and the 936 // "sum_of_squares" of the measurements, this returns the variance of the 937 // sequence. 938 inline double variance(int n, double sum_of_squares, double sum) { 939 double n_d = (double)n; 940 double avg = sum/n_d; 941 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 942 } 943 944 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP