1 /* 2 * Copyright (c) 2001, 2013, 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 "memory/collectorPolicy.hpp" 32 33 // A G1CollectorPolicy makes policy decisions that determine the 34 // characteristics of the collector. Examples include: 35 // * choice of collection set. 36 // * when to collect. 37 38 class HeapRegion; 39 class CollectionSetChooser; 40 class G1GCPhaseTimes; 41 42 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses 43 // (the latter may contain non-young regions - i.e. regions that are 44 // technically in old) while TraceOldGenTime collects data about full GCs. 45 class TraceYoungGenTimeData : public CHeapObj<mtGC> { 46 private: 47 unsigned _young_pause_num; 48 unsigned _mixed_pause_num; 49 50 NumberSeq _all_stop_world_times_ms; 51 NumberSeq _all_yield_times_ms; 52 53 NumberSeq _total; 54 NumberSeq _other; 55 NumberSeq _root_region_scan_wait; 56 NumberSeq _parallel; 57 NumberSeq _ext_root_scan; 58 NumberSeq _satb_filtering; 59 NumberSeq _update_rs; 60 NumberSeq _scan_rs; 61 NumberSeq _obj_copy; 62 NumberSeq _termination; 63 NumberSeq _parallel_other; 64 NumberSeq _clear_ct; 65 66 void print_summary(const char* str, const NumberSeq* seq) const; 67 void print_summary_sd(const char* str, const NumberSeq* seq) const; 68 69 public: 70 TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {}; 71 void record_start_collection(double time_to_stop_the_world_ms); 72 void record_yield_time(double yield_time_ms); 73 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times); 74 void increment_young_collection_count(); 75 void increment_mixed_collection_count(); 76 void print() const; 77 }; 78 79 class TraceOldGenTimeData : public CHeapObj<mtGC> { 80 private: 81 NumberSeq _all_full_gc_times; 82 83 public: 84 void record_full_collection(double full_gc_time_ms); 85 void print() const; 86 }; 87 88 // There are three command line options related to the young gen size: 89 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is 90 // just a short form for NewSize==MaxNewSize). G1 will use its internal 91 // heuristics to calculate the actual young gen size, so these options 92 // basically only limit the range within which G1 can pick a young gen 93 // size. Also, these are general options taking byte sizes. G1 will 94 // internally work with a number of regions instead. So, some rounding 95 // will occur. 96 // 97 // If nothing related to the the young gen size is set on the command 98 // line we should allow the young gen to be between G1NewSizePercent 99 // and G1MaxNewSizePercent of the heap size. This means that every time 100 // the heap size changes, the limits for the young gen size will be 101 // recalculated. 102 // 103 // If only -XX:NewSize is set we should use the specified value as the 104 // minimum size for young gen. Still using G1MaxNewSizePercent of the 105 // heap as maximum. 106 // 107 // If only -XX:MaxNewSize is set we should use the specified value as the 108 // maximum size for young gen. Still using G1NewSizePercent of the heap 109 // as minimum. 110 // 111 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values. 112 // No updates when the heap size changes. There is a special case when 113 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a 114 // different heuristic for calculating the collection set when we do mixed 115 // collection. 116 // 117 // If only -XX:NewRatio is set we should use the specified ratio of the heap 118 // as both min and max. This will be interpreted as "fixed" just like the 119 // NewSize==MaxNewSize case above. But we will update the min and max 120 // every time the heap size changes. 121 // 122 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is 123 // combined with either NewSize or MaxNewSize. (A warning message is printed.) 124 class G1YoungGenSizer : public CHeapObj<mtGC> { 125 private: 126 enum SizerKind { 127 SizerDefaults, 128 SizerNewSizeOnly, 129 SizerMaxNewSizeOnly, 130 SizerMaxAndNewSize, 131 SizerNewRatio 132 }; 133 SizerKind _sizer_kind; 134 uint _min_desired_young_length; 135 uint _max_desired_young_length; 136 bool _adaptive_size; 137 uint calculate_default_min_length(uint new_number_of_heap_regions); 138 uint calculate_default_max_length(uint new_number_of_heap_regions); 139 140 // Update the given values for minimum and maximum young gen length in regions 141 // given the number of heap regions depending on the kind of sizing algorithm. 142 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length); 143 144 public: 145 G1YoungGenSizer(); 146 // Calculate the maximum length of the young gen given the number of regions 147 // depending on the sizing algorithm. 148 uint max_young_length(uint number_of_heap_regions); 149 150 void heap_size_changed(uint new_number_of_heap_regions); 151 uint min_desired_young_length() { 152 return _min_desired_young_length; 153 } 154 uint max_desired_young_length() { 155 return _max_desired_young_length; 156 } 157 bool adaptive_young_list_length() { 158 return _adaptive_size; 159 } 160 }; 161 162 class G1CollectorPolicy: public CollectorPolicy { 163 private: 164 // either equal to the number of parallel threads, if ParallelGCThreads 165 // has been set, or 1 otherwise 166 int _parallel_gc_threads; 167 168 // The number of GC threads currently active. 169 uintx _no_of_gc_threads; 170 171 enum SomePrivateConstants { 172 NumPrevPausesForHeuristics = 10 173 }; 174 175 G1MMUTracker* _mmu_tracker; 176 177 void initialize_alignments(); 178 void initialize_flags(); 179 180 CollectionSetChooser* _collectionSetChooser; 181 182 double _full_collection_start_sec; 183 uint _cur_collection_pause_used_regions_at_start; 184 185 // These exclude marking times. 186 TruncatedSeq* _recent_gc_times_ms; 187 188 TruncatedSeq* _concurrent_mark_remark_times_ms; 189 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 190 191 TraceYoungGenTimeData _trace_young_gen_time_data; 192 TraceOldGenTimeData _trace_old_gen_time_data; 193 194 double _stop_world_start; 195 196 // indicates whether we are in young or mixed GC mode 197 bool _gcs_are_young; 198 199 uint _young_list_target_length; 200 uint _young_list_fixed_length; 201 202 // The max number of regions we can extend the eden by while the GC 203 // locker is active. This should be >= _young_list_target_length; 204 uint _young_list_max_length; 205 206 bool _last_gc_was_young; 207 208 bool _during_marking; 209 bool _in_marking_window; 210 bool _in_marking_window_im; 211 212 SurvRateGroup* _short_lived_surv_rate_group; 213 SurvRateGroup* _survivor_surv_rate_group; 214 // add here any more surv rate groups 215 216 double _gc_overhead_perc; 217 218 double _reserve_factor; 219 uint _reserve_regions; 220 221 bool during_marking() { 222 return _during_marking; 223 } 224 225 enum PredictionConstants { 226 TruncatedSeqLength = 10 227 }; 228 229 TruncatedSeq* _alloc_rate_ms_seq; 230 double _prev_collection_pause_end_ms; 231 232 TruncatedSeq* _rs_length_diff_seq; 233 TruncatedSeq* _cost_per_card_ms_seq; 234 TruncatedSeq* _young_cards_per_entry_ratio_seq; 235 TruncatedSeq* _mixed_cards_per_entry_ratio_seq; 236 TruncatedSeq* _cost_per_entry_ms_seq; 237 TruncatedSeq* _mixed_cost_per_entry_ms_seq; 238 TruncatedSeq* _cost_per_byte_ms_seq; 239 TruncatedSeq* _constant_other_time_ms_seq; 240 TruncatedSeq* _young_other_cost_per_region_ms_seq; 241 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 242 243 TruncatedSeq* _pending_cards_seq; 244 TruncatedSeq* _rs_lengths_seq; 245 246 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 247 248 G1YoungGenSizer* _young_gen_sizer; 249 250 uint _eden_cset_region_length; 251 uint _survivor_cset_region_length; 252 uint _old_cset_region_length; 253 254 void init_cset_region_lengths(uint eden_cset_region_length, 255 uint survivor_cset_region_length); 256 257 uint eden_cset_region_length() { return _eden_cset_region_length; } 258 uint survivor_cset_region_length() { return _survivor_cset_region_length; } 259 uint old_cset_region_length() { return _old_cset_region_length; } 260 261 uint _free_regions_at_end_of_collection; 262 263 size_t _recorded_rs_lengths; 264 size_t _max_rs_lengths; 265 double _sigma; 266 267 size_t _rs_lengths_prediction; 268 269 double sigma() { return _sigma; } 270 271 // A function that prevents us putting too much stock in small sample 272 // sets. Returns a number between 2.0 and 1.0, depending on the number 273 // of samples. 5 or more samples yields one; fewer scales linearly from 274 // 2.0 at 1 sample to 1.0 at 5. 275 double confidence_factor(int samples) { 276 if (samples > 4) return 1.0; 277 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 278 } 279 280 double get_new_neg_prediction(TruncatedSeq* seq) { 281 return seq->davg() - sigma() * seq->dsd(); 282 } 283 284 #ifndef PRODUCT 285 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 286 #endif // PRODUCT 287 288 void adjust_concurrent_refinement(double update_rs_time, 289 double update_rs_processed_buffers, 290 double goal_ms); 291 292 uintx no_of_gc_threads() { return _no_of_gc_threads; } 293 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; } 294 295 double _pause_time_target_ms; 296 297 size_t _pending_cards; 298 299 public: 300 // Accessors 301 302 void set_region_eden(HeapRegion* hr, int young_index_in_cset) { 303 hr->set_eden(); 304 hr->install_surv_rate_group(_short_lived_surv_rate_group); 305 hr->set_young_index_in_cset(young_index_in_cset); 306 } 307 308 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) { 309 assert(hr->is_survivor(), "pre-condition"); 310 hr->install_surv_rate_group(_survivor_surv_rate_group); 311 hr->set_young_index_in_cset(young_index_in_cset); 312 } 313 314 #ifndef PRODUCT 315 bool verify_young_ages(); 316 #endif // PRODUCT 317 318 double get_new_prediction(TruncatedSeq* seq) { 319 return MAX2(seq->davg() + sigma() * seq->dsd(), 320 seq->davg() * confidence_factor(seq->num())); 321 } 322 323 void record_max_rs_lengths(size_t rs_lengths) { 324 _max_rs_lengths = rs_lengths; 325 } 326 327 size_t predict_rs_length_diff() { 328 return (size_t) get_new_prediction(_rs_length_diff_seq); 329 } 330 331 double predict_alloc_rate_ms() { 332 return get_new_prediction(_alloc_rate_ms_seq); 333 } 334 335 double predict_cost_per_card_ms() { 336 return get_new_prediction(_cost_per_card_ms_seq); 337 } 338 339 double predict_rs_update_time_ms(size_t pending_cards) { 340 return (double) pending_cards * predict_cost_per_card_ms(); 341 } 342 343 double predict_young_cards_per_entry_ratio() { 344 return get_new_prediction(_young_cards_per_entry_ratio_seq); 345 } 346 347 double predict_mixed_cards_per_entry_ratio() { 348 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 349 return predict_young_cards_per_entry_ratio(); 350 } else { 351 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 352 } 353 } 354 355 size_t predict_young_card_num(size_t rs_length) { 356 return (size_t) ((double) rs_length * 357 predict_young_cards_per_entry_ratio()); 358 } 359 360 size_t predict_non_young_card_num(size_t rs_length) { 361 return (size_t) ((double) rs_length * 362 predict_mixed_cards_per_entry_ratio()); 363 } 364 365 double predict_rs_scan_time_ms(size_t card_num) { 366 if (gcs_are_young()) { 367 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 368 } else { 369 return predict_mixed_rs_scan_time_ms(card_num); 370 } 371 } 372 373 double predict_mixed_rs_scan_time_ms(size_t card_num) { 374 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 375 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 376 } else { 377 return (double) (card_num * 378 get_new_prediction(_mixed_cost_per_entry_ms_seq)); 379 } 380 } 381 382 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 383 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 384 return (1.1 * (double) bytes_to_copy) * 385 get_new_prediction(_cost_per_byte_ms_seq); 386 } else { 387 return (double) bytes_to_copy * 388 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 389 } 390 } 391 392 double predict_object_copy_time_ms(size_t bytes_to_copy) { 393 if (_in_marking_window && !_in_marking_window_im) { 394 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 395 } else { 396 return (double) bytes_to_copy * 397 get_new_prediction(_cost_per_byte_ms_seq); 398 } 399 } 400 401 double predict_constant_other_time_ms() { 402 return get_new_prediction(_constant_other_time_ms_seq); 403 } 404 405 double predict_young_other_time_ms(size_t young_num) { 406 return (double) young_num * 407 get_new_prediction(_young_other_cost_per_region_ms_seq); 408 } 409 410 double predict_non_young_other_time_ms(size_t non_young_num) { 411 return (double) non_young_num * 412 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 413 } 414 415 double predict_base_elapsed_time_ms(size_t pending_cards); 416 double predict_base_elapsed_time_ms(size_t pending_cards, 417 size_t scanned_cards); 418 size_t predict_bytes_to_copy(HeapRegion* hr); 419 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc); 420 421 void set_recorded_rs_lengths(size_t rs_lengths); 422 423 uint cset_region_length() { return young_cset_region_length() + 424 old_cset_region_length(); } 425 uint young_cset_region_length() { return eden_cset_region_length() + 426 survivor_cset_region_length(); } 427 428 double predict_survivor_regions_evac_time(); 429 430 void cset_regions_freed() { 431 bool propagate = _last_gc_was_young && !_in_marking_window; 432 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 433 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 434 // also call it on any more surv rate groups 435 } 436 437 G1MMUTracker* mmu_tracker() { 438 return _mmu_tracker; 439 } 440 441 double max_pause_time_ms() { 442 return _mmu_tracker->max_gc_time() * 1000.0; 443 } 444 445 double predict_remark_time_ms() { 446 return get_new_prediction(_concurrent_mark_remark_times_ms); 447 } 448 449 double predict_cleanup_time_ms() { 450 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 451 } 452 453 // Returns an estimate of the survival rate of the region at yg-age 454 // "yg_age". 455 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 456 TruncatedSeq* seq = surv_rate_group->get_seq(age); 457 if (seq->num() == 0) 458 gclog_or_tty->print("BARF! age is %d", age); 459 guarantee( seq->num() > 0, "invariant" ); 460 double pred = get_new_prediction(seq); 461 if (pred > 1.0) 462 pred = 1.0; 463 return pred; 464 } 465 466 double predict_yg_surv_rate(int age) { 467 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 468 } 469 470 double accum_yg_surv_rate_pred(int age) { 471 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 472 } 473 474 private: 475 // Statistics kept per GC stoppage, pause or full. 476 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 477 478 // Add a new GC of the given duration and end time to the record. 479 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 480 481 // The head of the list (via "next_in_collection_set()") representing the 482 // current collection set. Set from the incrementally built collection 483 // set at the start of the pause. 484 HeapRegion* _collection_set; 485 486 // The number of bytes in the collection set before the pause. Set from 487 // the incrementally built collection set at the start of an evacuation 488 // pause, and incremented in finalize_cset() when adding old regions 489 // (if any) to the collection set. 490 size_t _collection_set_bytes_used_before; 491 492 // The number of bytes copied during the GC. 493 size_t _bytes_copied_during_gc; 494 495 // The associated information that is maintained while the incremental 496 // collection set is being built with young regions. Used to populate 497 // the recorded info for the evacuation pause. 498 499 enum CSetBuildType { 500 Active, // We are actively building the collection set 501 Inactive // We are not actively building the collection set 502 }; 503 504 CSetBuildType _inc_cset_build_state; 505 506 // The head of the incrementally built collection set. 507 HeapRegion* _inc_cset_head; 508 509 // The tail of the incrementally built collection set. 510 HeapRegion* _inc_cset_tail; 511 512 // The number of bytes in the incrementally built collection set. 513 // Used to set _collection_set_bytes_used_before at the start of 514 // an evacuation pause. 515 size_t _inc_cset_bytes_used_before; 516 517 // Used to record the highest end of heap region in collection set 518 HeapWord* _inc_cset_max_finger; 519 520 // The RSet lengths recorded for regions in the CSet. It is updated 521 // by the thread that adds a new region to the CSet. We assume that 522 // only one thread can be allocating a new CSet region (currently, 523 // it does so after taking the Heap_lock) hence no need to 524 // synchronize updates to this field. 525 size_t _inc_cset_recorded_rs_lengths; 526 527 // A concurrent refinement thread periodically samples the young 528 // region RSets and needs to update _inc_cset_recorded_rs_lengths as 529 // the RSets grow. Instead of having to synchronize updates to that 530 // field we accumulate them in this field and add it to 531 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC. 532 ssize_t _inc_cset_recorded_rs_lengths_diffs; 533 534 // The predicted elapsed time it will take to collect the regions in 535 // the CSet. This is updated by the thread that adds a new region to 536 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about 537 // MT-safety assumptions. 538 double _inc_cset_predicted_elapsed_time_ms; 539 540 // See the comment for _inc_cset_recorded_rs_lengths_diffs. 541 double _inc_cset_predicted_elapsed_time_ms_diffs; 542 543 // Stash a pointer to the g1 heap. 544 G1CollectedHeap* _g1; 545 546 G1GCPhaseTimes* _phase_times; 547 548 // The ratio of gc time to elapsed time, computed over recent pauses. 549 double _recent_avg_pause_time_ratio; 550 551 double recent_avg_pause_time_ratio() { 552 return _recent_avg_pause_time_ratio; 553 } 554 555 // At the end of a pause we check the heap occupancy and we decide 556 // whether we will start a marking cycle during the next pause. If 557 // we decide that we want to do that, we will set this parameter to 558 // true. So, this parameter will stay true between the end of a 559 // pause and the beginning of a subsequent pause (not necessarily 560 // the next one, see the comments on the next field) when we decide 561 // that we will indeed start a marking cycle and do the initial-mark 562 // work. 563 volatile bool _initiate_conc_mark_if_possible; 564 565 // If initiate_conc_mark_if_possible() is set at the beginning of a 566 // pause, it is a suggestion that the pause should start a marking 567 // cycle by doing the initial-mark work. However, it is possible 568 // that the concurrent marking thread is still finishing up the 569 // previous marking cycle (e.g., clearing the next marking 570 // bitmap). If that is the case we cannot start a new cycle and 571 // we'll have to wait for the concurrent marking thread to finish 572 // what it is doing. In this case we will postpone the marking cycle 573 // initiation decision for the next pause. When we eventually decide 574 // to start a cycle, we will set _during_initial_mark_pause which 575 // will stay true until the end of the initial-mark pause and it's 576 // the condition that indicates that a pause is doing the 577 // initial-mark work. 578 volatile bool _during_initial_mark_pause; 579 580 bool _last_young_gc; 581 582 // This set of variables tracks the collector efficiency, in order to 583 // determine whether we should initiate a new marking. 584 double _cur_mark_stop_world_time_ms; 585 double _mark_remark_start_sec; 586 double _mark_cleanup_start_sec; 587 588 // Update the young list target length either by setting it to the 589 // desired fixed value or by calculating it using G1's pause 590 // prediction model. If no rs_lengths parameter is passed, predict 591 // the RS lengths using the prediction model, otherwise use the 592 // given rs_lengths as the prediction. 593 void update_young_list_target_length(size_t rs_lengths = (size_t) -1); 594 595 // Calculate and return the minimum desired young list target 596 // length. This is the minimum desired young list length according 597 // to the user's inputs. 598 uint calculate_young_list_desired_min_length(uint base_min_length); 599 600 // Calculate and return the maximum desired young list target 601 // length. This is the maximum desired young list length according 602 // to the user's inputs. 603 uint calculate_young_list_desired_max_length(); 604 605 // Calculate and return the maximum young list target length that 606 // can fit into the pause time goal. The parameters are: rs_lengths 607 // represent the prediction of how large the young RSet lengths will 608 // be, base_min_length is the already existing number of regions in 609 // the young list, min_length and max_length are the desired min and 610 // max young list length according to the user's inputs. 611 uint calculate_young_list_target_length(size_t rs_lengths, 612 uint base_min_length, 613 uint desired_min_length, 614 uint desired_max_length); 615 616 // Calculate and return chunk size (in number of regions) for parallel 617 // concurrent mark cleanup. 618 uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions); 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(); 643 644 virtual G1CollectorPolicy* as_g1_policy() { return this; } 645 646 virtual CollectorPolicy::Name kind() { 647 return CollectorPolicy::G1CollectorPolicyKind; 648 } 649 650 G1GCPhaseTimes* phase_times() const { return _phase_times; } 651 652 // Check the current value of the young list RSet lengths and 653 // compare it against the last prediction. If the current value is 654 // higher, recalculate the young list target length prediction. 655 void revise_young_list_target_length_if_necessary(); 656 657 // This should be called after the heap is resized. 658 void record_new_heap_size(uint new_number_of_regions); 659 660 void init(); 661 662 // Create jstat counters for the policy. 663 virtual void initialize_gc_policy_counters(); 664 665 virtual HeapWord* mem_allocate_work(size_t size, 666 bool is_tlab, 667 bool* gc_overhead_limit_was_exceeded); 668 669 // This method controls how a collector handles one or more 670 // of its generations being fully allocated. 671 virtual HeapWord* satisfy_failed_allocation(size_t size, 672 bool is_tlab); 673 674 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 675 676 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 677 678 // Record the start and end of an evacuation pause. 679 void record_collection_pause_start(double start_time_sec); 680 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info); 681 682 // Record the start and end of a full collection. 683 void record_full_collection_start(); 684 void record_full_collection_end(); 685 686 // Must currently be called while the world is stopped. 687 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms); 688 689 // Record start and end of remark. 690 void record_concurrent_mark_remark_start(); 691 void record_concurrent_mark_remark_end(); 692 693 // Record start, end, and completion of cleanup. 694 void record_concurrent_mark_cleanup_start(); 695 void record_concurrent_mark_cleanup_end(uint n_workers); 696 void record_concurrent_mark_cleanup_completed(); 697 698 // Records the information about the heap size for reporting in 699 // print_detailed_heap_transition 700 void record_heap_size_info_at_start(bool full); 701 702 // Print heap sizing transition (with less and more detail). 703 704 void print_heap_transition(size_t bytes_before); 705 void print_heap_transition(); 706 void print_detailed_heap_transition(bool full = false); 707 708 void record_stop_world_start(); 709 void record_concurrent_pause(); 710 711 // Record how much space we copied during a GC. This is typically 712 // called when a GC alloc region is being retired. 713 void record_bytes_copied_during_gc(size_t bytes) { 714 _bytes_copied_during_gc += bytes; 715 } 716 717 // The amount of space we copied during a GC. 718 size_t bytes_copied_during_gc() { 719 return _bytes_copied_during_gc; 720 } 721 722 // Determine whether there are candidate regions so that the 723 // next GC should be mixed. The two action strings are used 724 // in the ergo output when the method returns true or false. 725 bool next_gc_should_be_mixed(const char* true_action_str, 726 const char* false_action_str); 727 728 // Choose a new collection set. Marks the chosen regions as being 729 // "in_collection_set", and links them together. The head and number of 730 // the collection set are available via access methods. 731 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info); 732 733 // The head of the list (via "next_in_collection_set()") representing the 734 // current collection set. 735 HeapRegion* collection_set() { return _collection_set; } 736 737 void clear_collection_set() { _collection_set = NULL; } 738 739 // Add old region "hr" to the CSet. 740 void add_old_region_to_cset(HeapRegion* hr); 741 742 // Incremental CSet Support 743 744 // The head of the incrementally built collection set. 745 HeapRegion* inc_cset_head() { return _inc_cset_head; } 746 747 // The tail of the incrementally built collection set. 748 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 749 750 // Initialize incremental collection set info. 751 void start_incremental_cset_building(); 752 753 // Perform any final calculations on the incremental CSet fields 754 // before we can use them. 755 void finalize_incremental_cset_building(); 756 757 void clear_incremental_cset() { 758 _inc_cset_head = NULL; 759 _inc_cset_tail = NULL; 760 } 761 762 // Stop adding regions to the incremental collection set 763 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 764 765 // Add information about hr to the aggregated information for the 766 // incrementally built collection set. 767 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 768 769 // Update information about hr in the aggregated information for 770 // the incrementally built collection set. 771 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 772 773 private: 774 // Update the incremental cset information when adding a region 775 // (should not be called directly). 776 void add_region_to_incremental_cset_common(HeapRegion* hr); 777 778 public: 779 // Add hr to the LHS of the incremental collection set. 780 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 781 782 // Add hr to the RHS of the incremental collection set. 783 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 784 785 #ifndef PRODUCT 786 void print_collection_set(HeapRegion* list_head, outputStream* st); 787 #endif // !PRODUCT 788 789 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 790 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 791 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 792 793 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 794 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 795 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 796 797 // This sets the initiate_conc_mark_if_possible() flag to start a 798 // new cycle, as long as we are not already in one. It's best if it 799 // is called during a safepoint when the test whether a cycle is in 800 // progress or not is stable. 801 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause); 802 803 // This is called at the very beginning of an evacuation pause (it 804 // has to be the first thing that the pause does). If 805 // initiate_conc_mark_if_possible() is true, and the concurrent 806 // marking thread has completed its work during the previous cycle, 807 // it will set during_initial_mark_pause() to so that the pause does 808 // the initial-mark work and start a marking cycle. 809 void decide_on_conc_mark_initiation(); 810 811 // If an expansion would be appropriate, because recent GC overhead had 812 // exceeded the desired limit, return an amount to expand by. 813 virtual size_t expansion_amount(); 814 815 // Print tracing information. 816 void print_tracing_info() const; 817 818 // Print stats on young survival ratio 819 void print_yg_surv_rate_info() const; 820 821 void finished_recalculating_age_indexes(bool is_survivors) { 822 if (is_survivors) { 823 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 824 } else { 825 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 826 } 827 // do that for any other surv rate groups 828 } 829 830 size_t young_list_target_length() const { return _young_list_target_length; } 831 832 bool is_young_list_full(); 833 834 bool can_expand_young_list(); 835 836 uint young_list_max_length() { 837 return _young_list_max_length; 838 } 839 840 bool gcs_are_young() { 841 return _gcs_are_young; 842 } 843 void set_gcs_are_young(bool gcs_are_young) { 844 _gcs_are_young = gcs_are_young; 845 } 846 847 bool adaptive_young_list_length() { 848 return _young_gen_sizer->adaptive_young_list_length(); 849 } 850 851 private: 852 // 853 // Survivor regions policy. 854 // 855 856 // Current tenuring threshold, set to 0 if the collector reaches the 857 // maximum amount of survivors regions. 858 uint _tenuring_threshold; 859 860 // The limit on the number of regions allocated for survivors. 861 uint _max_survivor_regions; 862 863 // For reporting purposes. 864 // The value of _heap_bytes_before_gc is also used to calculate 865 // the cost of copying. 866 867 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC 868 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC 869 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC 870 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC 871 872 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC 873 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC 874 875 // The amount of survivor regions after a collection. 876 uint _recorded_survivor_regions; 877 // List of survivor regions. 878 HeapRegion* _recorded_survivor_head; 879 HeapRegion* _recorded_survivor_tail; 880 881 ageTable _survivors_age_table; 882 883 public: 884 uint tenuring_threshold() const { return _tenuring_threshold; } 885 886 static const uint REGIONS_UNLIMITED = (uint) -1; 887 888 uint max_regions(InCSetState dest) { 889 switch (dest.value()) { 890 case InCSetState::Young: 891 return _max_survivor_regions; 892 case InCSetState::Old: 893 return REGIONS_UNLIMITED; 894 default: 895 assert(false, err_msg("Unknown dest state: " CSETSTATE_FORMAT, dest.value())); 896 break; 897 } 898 // keep some compilers happy 899 return 0; 900 } 901 902 void note_start_adding_survivor_regions() { 903 _survivor_surv_rate_group->start_adding_regions(); 904 } 905 906 void note_stop_adding_survivor_regions() { 907 _survivor_surv_rate_group->stop_adding_regions(); 908 } 909 910 void record_survivor_regions(uint regions, 911 HeapRegion* head, 912 HeapRegion* tail) { 913 _recorded_survivor_regions = regions; 914 _recorded_survivor_head = head; 915 _recorded_survivor_tail = tail; 916 } 917 918 uint recorded_survivor_regions() { 919 return _recorded_survivor_regions; 920 } 921 922 void record_thread_age_table(ageTable* age_table) { 923 _survivors_age_table.merge_par(age_table); 924 } 925 926 void update_max_gc_locker_expansion(); 927 928 // Calculates survivor space parameters. 929 void update_survivors_policy(); 930 931 virtual void post_heap_initialize(); 932 }; 933 934 // This should move to some place more general... 935 936 // If we have "n" measurements, and we've kept track of their "sum" and the 937 // "sum_of_squares" of the measurements, this returns the variance of the 938 // sequence. 939 inline double variance(int n, double sum_of_squares, double sum) { 940 double n_d = (double)n; 941 double avg = sum/n_d; 942 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 943 } 944 945 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP