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/g1MMUTracker.hpp" 30 #include "memory/collectorPolicy.hpp" 31 32 // A G1CollectorPolicy makes policy decisions that determine the 33 // characteristics of the collector. Examples include: 34 // * choice of collection set. 35 // * when to collect. 36 37 class HeapRegion; 38 class CollectionSetChooser; 39 class G1GCPhaseTimes; 40 41 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses 42 // (the latter may contain non-young regions - i.e. regions that are 43 // technically in old) while TraceOldGenTime collects data about full GCs. 44 class TraceYoungGenTimeData : public CHeapObj<mtGC> { 45 private: 46 unsigned _young_pause_num; 47 unsigned _mixed_pause_num; 48 49 NumberSeq _all_stop_world_times_ms; 50 NumberSeq _all_yield_times_ms; 51 52 NumberSeq _total; 53 NumberSeq _other; 54 NumberSeq _root_region_scan_wait; 55 NumberSeq _parallel; 56 NumberSeq _ext_root_scan; 57 NumberSeq _satb_filtering; 58 NumberSeq _update_rs; 59 NumberSeq _scan_rs; 60 NumberSeq _obj_copy; 61 NumberSeq _termination; 62 NumberSeq _parallel_other; 63 NumberSeq _clear_ct; 64 65 void print_summary(const char* str, const NumberSeq* seq) const; 66 void print_summary_sd(const char* str, const NumberSeq* seq) const; 67 68 public: 69 TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {}; 70 void record_start_collection(double time_to_stop_the_world_ms); 71 void record_yield_time(double yield_time_ms); 72 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times); 73 void increment_young_collection_count(); 74 void increment_mixed_collection_count(); 75 void print() const; 76 }; 77 78 class TraceOldGenTimeData : public CHeapObj<mtGC> { 79 private: 80 NumberSeq _all_full_gc_times; 81 82 public: 83 void record_full_collection(double full_gc_time_ms); 84 void print() const; 85 }; 86 87 // There are three command line options related to the young gen size: 88 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is 89 // just a short form for NewSize==MaxNewSize). G1 will use its internal 90 // heuristics to calculate the actual young gen size, so these options 91 // basically only limit the range within which G1 can pick a young gen 92 // size. Also, these are general options taking byte sizes. G1 will 93 // internally work with a number of regions instead. So, some rounding 94 // will occur. 95 // 96 // If nothing related to the the young gen size is set on the command 97 // line we should allow the young gen to be between G1NewSizePercent 98 // and G1MaxNewSizePercent of the heap size. This means that every time 99 // the heap size changes, the limits for the young gen size will be 100 // recalculated. 101 // 102 // If only -XX:NewSize is set we should use the specified value as the 103 // minimum size for young gen. Still using G1MaxNewSizePercent of the 104 // heap as maximum. 105 // 106 // If only -XX:MaxNewSize is set we should use the specified value as the 107 // maximum size for young gen. Still using G1NewSizePercent of the heap 108 // as minimum. 109 // 110 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values. 111 // No updates when the heap size changes. There is a special case when 112 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a 113 // different heuristic for calculating the collection set when we do mixed 114 // collection. 115 // 116 // If only -XX:NewRatio is set we should use the specified ratio of the heap 117 // as both min and max. This will be interpreted as "fixed" just like the 118 // NewSize==MaxNewSize case above. But we will update the min and max 119 // every time the heap size changes. 120 // 121 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is 122 // combined with either NewSize or MaxNewSize. (A warning message is printed.) 123 class G1YoungGenSizer : public CHeapObj<mtGC> { 124 private: 125 enum SizerKind { 126 SizerDefaults, 127 SizerNewSizeOnly, 128 SizerMaxNewSizeOnly, 129 SizerMaxAndNewSize, 130 SizerNewRatio 131 }; 132 SizerKind _sizer_kind; 133 uint _min_desired_young_length; 134 uint _max_desired_young_length; 135 bool _adaptive_size; 136 uint calculate_default_min_length(uint new_number_of_heap_regions); 137 uint calculate_default_max_length(uint new_number_of_heap_regions); 138 139 // Update the given values for minimum and maximum young gen length in regions 140 // given the number of heap regions depending on the kind of sizing algorithm. 141 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length); 142 143 public: 144 G1YoungGenSizer(); 145 // Calculate the maximum length of the young gen given the number of regions 146 // depending on the sizing algorithm. 147 uint max_young_length(uint number_of_heap_regions); 148 149 void heap_size_changed(uint new_number_of_heap_regions); 150 uint min_desired_young_length() { 151 return _min_desired_young_length; 152 } 153 uint max_desired_young_length() { 154 return _max_desired_young_length; 155 } 156 bool adaptive_young_list_length() { 157 return _adaptive_size; 158 } 159 }; 160 161 class G1CollectorPolicy: public CollectorPolicy { 162 private: 163 // either equal to the number of parallel threads, if ParallelGCThreads 164 // has been set, or 1 otherwise 165 int _parallel_gc_threads; 166 167 // The number of GC threads currently active. 168 uintx _no_of_gc_threads; 169 170 enum SomePrivateConstants { 171 NumPrevPausesForHeuristics = 10 172 }; 173 174 G1MMUTracker* _mmu_tracker; 175 176 void initialize_alignments(); 177 void initialize_flags(); 178 179 CollectionSetChooser* _collectionSetChooser; 180 181 double _full_collection_start_sec; 182 uint _cur_collection_pause_used_regions_at_start; 183 184 // These exclude marking times. 185 TruncatedSeq* _recent_gc_times_ms; 186 187 TruncatedSeq* _concurrent_mark_remark_times_ms; 188 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 189 190 TraceYoungGenTimeData _trace_young_gen_time_data; 191 TraceOldGenTimeData _trace_old_gen_time_data; 192 193 double _stop_world_start; 194 195 // indicates whether we are in young or mixed GC mode 196 bool _gcs_are_young; 197 198 uint _young_list_target_length; 199 uint _young_list_fixed_length; 200 201 // The max number of regions we can extend the eden by while the GC 202 // locker is active. This should be >= _young_list_target_length; 203 uint _young_list_max_length; 204 205 bool _last_gc_was_young; 206 207 bool _during_marking; 208 bool _in_marking_window; 209 bool _in_marking_window_im; 210 211 SurvRateGroup* _short_lived_surv_rate_group; 212 SurvRateGroup* _survivor_surv_rate_group; 213 // add here any more surv rate groups 214 215 double _gc_overhead_perc; 216 217 double _reserve_factor; 218 uint _reserve_regions; 219 220 bool during_marking() { 221 return _during_marking; 222 } 223 224 enum PredictionConstants { 225 TruncatedSeqLength = 10 226 }; 227 228 TruncatedSeq* _alloc_rate_ms_seq; 229 double _prev_collection_pause_end_ms; 230 231 TruncatedSeq* _rs_length_diff_seq; 232 TruncatedSeq* _cost_per_card_ms_seq; 233 TruncatedSeq* _young_cards_per_entry_ratio_seq; 234 TruncatedSeq* _mixed_cards_per_entry_ratio_seq; 235 TruncatedSeq* _cost_per_entry_ms_seq; 236 TruncatedSeq* _mixed_cost_per_entry_ms_seq; 237 TruncatedSeq* _cost_per_byte_ms_seq; 238 TruncatedSeq* _constant_other_time_ms_seq; 239 TruncatedSeq* _young_other_cost_per_region_ms_seq; 240 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 241 242 TruncatedSeq* _pending_cards_seq; 243 TruncatedSeq* _rs_lengths_seq; 244 245 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 246 247 G1YoungGenSizer* _young_gen_sizer; 248 249 uint _eden_cset_region_length; 250 uint _survivor_cset_region_length; 251 uint _old_cset_region_length; 252 253 void init_cset_region_lengths(uint eden_cset_region_length, 254 uint survivor_cset_region_length); 255 256 uint eden_cset_region_length() { return _eden_cset_region_length; } 257 uint survivor_cset_region_length() { return _survivor_cset_region_length; } 258 uint old_cset_region_length() { return _old_cset_region_length; } 259 260 uint _free_regions_at_end_of_collection; 261 262 size_t _recorded_rs_lengths; 263 size_t _max_rs_lengths; 264 double _sigma; 265 266 size_t _rs_lengths_prediction; 267 268 double sigma() { return _sigma; } 269 270 // A function that prevents us putting too much stock in small sample 271 // sets. Returns a number between 2.0 and 1.0, depending on the number 272 // of samples. 5 or more samples yields one; fewer scales linearly from 273 // 2.0 at 1 sample to 1.0 at 5. 274 double confidence_factor(int samples) { 275 if (samples > 4) return 1.0; 276 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 277 } 278 279 double get_new_neg_prediction(TruncatedSeq* seq) { 280 return seq->davg() - sigma() * seq->dsd(); 281 } 282 283 #ifndef PRODUCT 284 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 285 #endif // PRODUCT 286 287 void adjust_concurrent_refinement(double update_rs_time, 288 double update_rs_processed_buffers, 289 double goal_ms); 290 291 uintx no_of_gc_threads() { return _no_of_gc_threads; } 292 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; } 293 294 double _pause_time_target_ms; 295 296 size_t _pending_cards; 297 298 public: 299 // Accessors 300 301 void set_region_eden(HeapRegion* hr, int young_index_in_cset) { 302 hr->set_young(); 303 hr->install_surv_rate_group(_short_lived_surv_rate_group); 304 hr->set_young_index_in_cset(young_index_in_cset); 305 } 306 307 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) { 308 assert(hr->is_young() && hr->is_survivor(), "pre-condition"); 309 hr->install_surv_rate_group(_survivor_surv_rate_group); 310 hr->set_young_index_in_cset(young_index_in_cset); 311 } 312 313 #ifndef PRODUCT 314 bool verify_young_ages(); 315 #endif // PRODUCT 316 317 double get_new_prediction(TruncatedSeq* seq) { 318 return MAX2(seq->davg() + sigma() * seq->dsd(), 319 seq->davg() * confidence_factor(seq->num())); 320 } 321 322 void record_max_rs_lengths(size_t rs_lengths) { 323 _max_rs_lengths = rs_lengths; 324 } 325 326 size_t predict_rs_length_diff() { 327 return (size_t) get_new_prediction(_rs_length_diff_seq); 328 } 329 330 double predict_alloc_rate_ms() { 331 return get_new_prediction(_alloc_rate_ms_seq); 332 } 333 334 double predict_cost_per_card_ms() { 335 return get_new_prediction(_cost_per_card_ms_seq); 336 } 337 338 double predict_rs_update_time_ms(size_t pending_cards) { 339 return (double) pending_cards * predict_cost_per_card_ms(); 340 } 341 342 double predict_young_cards_per_entry_ratio() { 343 return get_new_prediction(_young_cards_per_entry_ratio_seq); 344 } 345 346 double predict_mixed_cards_per_entry_ratio() { 347 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 348 return predict_young_cards_per_entry_ratio(); 349 } else { 350 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 351 } 352 } 353 354 size_t predict_young_card_num(size_t rs_length) { 355 return (size_t) ((double) rs_length * 356 predict_young_cards_per_entry_ratio()); 357 } 358 359 size_t predict_non_young_card_num(size_t rs_length) { 360 return (size_t) ((double) rs_length * 361 predict_mixed_cards_per_entry_ratio()); 362 } 363 364 double predict_rs_scan_time_ms(size_t card_num) { 365 if (gcs_are_young()) { 366 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 367 } else { 368 return predict_mixed_rs_scan_time_ms(card_num); 369 } 370 } 371 372 double predict_mixed_rs_scan_time_ms(size_t card_num) { 373 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 374 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 375 } else { 376 return (double) (card_num * 377 get_new_prediction(_mixed_cost_per_entry_ms_seq)); 378 } 379 } 380 381 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 382 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 383 return (1.1 * (double) bytes_to_copy) * 384 get_new_prediction(_cost_per_byte_ms_seq); 385 } else { 386 return (double) bytes_to_copy * 387 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 388 } 389 } 390 391 double predict_object_copy_time_ms(size_t bytes_to_copy) { 392 if (_in_marking_window && !_in_marking_window_im) { 393 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 394 } else { 395 return (double) bytes_to_copy * 396 get_new_prediction(_cost_per_byte_ms_seq); 397 } 398 } 399 400 double predict_constant_other_time_ms() { 401 return get_new_prediction(_constant_other_time_ms_seq); 402 } 403 404 double predict_young_other_time_ms(size_t young_num) { 405 return (double) young_num * 406 get_new_prediction(_young_other_cost_per_region_ms_seq); 407 } 408 409 double predict_non_young_other_time_ms(size_t non_young_num) { 410 return (double) non_young_num * 411 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 412 } 413 414 double predict_base_elapsed_time_ms(size_t pending_cards); 415 double predict_base_elapsed_time_ms(size_t pending_cards, 416 size_t scanned_cards); 417 size_t predict_bytes_to_copy(HeapRegion* hr); 418 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc); 419 420 void set_recorded_rs_lengths(size_t rs_lengths); 421 422 uint cset_region_length() { return young_cset_region_length() + 423 old_cset_region_length(); } 424 uint young_cset_region_length() { return eden_cset_region_length() + 425 survivor_cset_region_length(); } 426 427 double predict_survivor_regions_evac_time(); 428 429 void cset_regions_freed() { 430 bool propagate = _last_gc_was_young && !_in_marking_window; 431 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 432 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 433 // also call it on any more surv rate groups 434 } 435 436 G1MMUTracker* mmu_tracker() { 437 return _mmu_tracker; 438 } 439 440 double max_pause_time_ms() { 441 return _mmu_tracker->max_gc_time() * 1000.0; 442 } 443 444 double predict_remark_time_ms() { 445 return get_new_prediction(_concurrent_mark_remark_times_ms); 446 } 447 448 double predict_cleanup_time_ms() { 449 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 450 } 451 452 // Returns an estimate of the survival rate of the region at yg-age 453 // "yg_age". 454 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 455 TruncatedSeq* seq = surv_rate_group->get_seq(age); 456 if (seq->num() == 0) 457 gclog_or_tty->print("BARF! age is %d", age); 458 guarantee( seq->num() > 0, "invariant" ); 459 double pred = get_new_prediction(seq); 460 if (pred > 1.0) 461 pred = 1.0; 462 return pred; 463 } 464 465 double predict_yg_surv_rate(int age) { 466 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 467 } 468 469 double accum_yg_surv_rate_pred(int age) { 470 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 471 } 472 473 private: 474 // Statistics kept per GC stoppage, pause or full. 475 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 476 477 // Add a new GC of the given duration and end time to the record. 478 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 479 480 // The head of the list (via "next_in_collection_set()") representing the 481 // current collection set. Set from the incrementally built collection 482 // set at the start of the pause. 483 HeapRegion* _collection_set; 484 485 // The number of bytes in the collection set before the pause. Set from 486 // the incrementally built collection set at the start of an evacuation 487 // pause, and incremented in finalize_cset() when adding old regions 488 // (if any) to the collection set. 489 size_t _collection_set_bytes_used_before; 490 491 // The number of bytes copied during the GC. 492 size_t _bytes_copied_during_gc; 493 494 // The associated information that is maintained while the incremental 495 // collection set is being built with young regions. Used to populate 496 // the recorded info for the evacuation pause. 497 498 enum CSetBuildType { 499 Active, // We are actively building the collection set 500 Inactive // We are not actively building the collection set 501 }; 502 503 CSetBuildType _inc_cset_build_state; 504 505 // The head of the incrementally built collection set. 506 HeapRegion* _inc_cset_head; 507 508 // The tail of the incrementally built collection set. 509 HeapRegion* _inc_cset_tail; 510 511 // The number of bytes in the incrementally built collection set. 512 // Used to set _collection_set_bytes_used_before at the start of 513 // an evacuation pause. 514 size_t _inc_cset_bytes_used_before; 515 516 // Used to record the highest end of heap region in collection set 517 HeapWord* _inc_cset_max_finger; 518 519 // The RSet lengths recorded for regions in the CSet. It is updated 520 // by the thread that adds a new region to the CSet. We assume that 521 // only one thread can be allocating a new CSet region (currently, 522 // it does so after taking the Heap_lock) hence no need to 523 // synchronize updates to this field. 524 size_t _inc_cset_recorded_rs_lengths; 525 526 // A concurrent refinement thread periodically samples the young 527 // region RSets and needs to update _inc_cset_recorded_rs_lengths as 528 // the RSets grow. Instead of having to synchronize updates to that 529 // field we accumulate them in this field and add it to 530 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC. 531 ssize_t _inc_cset_recorded_rs_lengths_diffs; 532 533 // The predicted elapsed time it will take to collect the regions in 534 // the CSet. This is updated by the thread that adds a new region to 535 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about 536 // MT-safety assumptions. 537 double _inc_cset_predicted_elapsed_time_ms; 538 539 // See the comment for _inc_cset_recorded_rs_lengths_diffs. 540 double _inc_cset_predicted_elapsed_time_ms_diffs; 541 542 // Stash a pointer to the g1 heap. 543 G1CollectedHeap* _g1; 544 545 G1GCPhaseTimes* _phase_times; 546 547 // The ratio of gc time to elapsed time, computed over recent pauses. 548 double _recent_avg_pause_time_ratio; 549 550 double recent_avg_pause_time_ratio() { 551 return _recent_avg_pause_time_ratio; 552 } 553 554 // At the end of a pause we check the heap occupancy and we decide 555 // whether we will start a marking cycle during the next pause. If 556 // we decide that we want to do that, we will set this parameter to 557 // true. So, this parameter will stay true between the end of a 558 // pause and the beginning of a subsequent pause (not necessarily 559 // the next one, see the comments on the next field) when we decide 560 // that we will indeed start a marking cycle and do the initial-mark 561 // work. 562 volatile bool _initiate_conc_mark_if_possible; 563 564 // If initiate_conc_mark_if_possible() is set at the beginning of a 565 // pause, it is a suggestion that the pause should start a marking 566 // cycle by doing the initial-mark work. However, it is possible 567 // that the concurrent marking thread is still finishing up the 568 // previous marking cycle (e.g., clearing the next marking 569 // bitmap). If that is the case we cannot start a new cycle and 570 // we'll have to wait for the concurrent marking thread to finish 571 // what it is doing. In this case we will postpone the marking cycle 572 // initiation decision for the next pause. When we eventually decide 573 // to start a cycle, we will set _during_initial_mark_pause which 574 // will stay true until the end of the initial-mark pause and it's 575 // the condition that indicates that a pause is doing the 576 // initial-mark work. 577 volatile bool _during_initial_mark_pause; 578 579 bool _last_young_gc; 580 581 // This set of variables tracks the collector efficiency, in order to 582 // determine whether we should initiate a new marking. 583 double _cur_mark_stop_world_time_ms; 584 double _mark_remark_start_sec; 585 double _mark_cleanup_start_sec; 586 587 // Update the young list target length either by setting it to the 588 // desired fixed value or by calculating it using G1's pause 589 // prediction model. If no rs_lengths parameter is passed, predict 590 // the RS lengths using the prediction model, otherwise use the 591 // given rs_lengths as the prediction. 592 void update_young_list_target_length(size_t rs_lengths = (size_t) -1); 593 594 // Calculate and return the minimum desired young list target 595 // length. This is the minimum desired young list length according 596 // to the user's inputs. 597 uint calculate_young_list_desired_min_length(uint base_min_length); 598 599 // Calculate and return the maximum desired young list target 600 // length. This is the maximum desired young list length according 601 // to the user's inputs. 602 uint calculate_young_list_desired_max_length(); 603 604 // Calculate and return the maximum young list target length that 605 // can fit into the pause time goal. The parameters are: rs_lengths 606 // represent the prediction of how large the young RSet lengths will 607 // be, base_min_length is the already existing number of regions in 608 // the young list, min_length and max_length are the desired min and 609 // max young list length according to the user's inputs. 610 uint calculate_young_list_target_length(size_t rs_lengths, 611 uint base_min_length, 612 uint desired_min_length, 613 uint desired_max_length); 614 615 // Calculate and return chunk size (in number of regions) for parallel 616 // concurrent mark cleanup. 617 uint calculate_parallel_work_chunk_size(int n_workers, uint n_regions); 618 619 // Check whether a given young length (young_length) fits into the 620 // given target pause time and whether the prediction for the amount 621 // of objects to be copied for the given length will fit into the 622 // given free space (expressed by base_free_regions). It is used by 623 // calculate_young_list_target_length(). 624 bool predict_will_fit(uint young_length, double base_time_ms, 625 uint base_free_regions, double target_pause_time_ms); 626 627 // Calculate the minimum number of old regions we'll add to the CSet 628 // during a mixed GC. 629 uint calc_min_old_cset_length(); 630 631 // Calculate the maximum number of old regions we'll add to the CSet 632 // during a mixed GC. 633 uint calc_max_old_cset_length(); 634 635 // Returns the given amount of uncollected reclaimable space 636 // as a percentage of the current heap capacity. 637 double reclaimable_bytes_perc(size_t reclaimable_bytes); 638 639 public: 640 641 G1CollectorPolicy(); 642 643 virtual G1CollectorPolicy* as_g1_policy() { return this; } 644 645 virtual CollectorPolicy::Name kind() { 646 return CollectorPolicy::G1CollectorPolicyKind; 647 } 648 649 G1GCPhaseTimes* phase_times() const { return _phase_times; } 650 651 // Check the current value of the young list RSet lengths and 652 // compare it against the last prediction. If the current value is 653 // higher, recalculate the young list target length prediction. 654 void revise_young_list_target_length_if_necessary(); 655 656 // This should be called after the heap is resized. 657 void record_new_heap_size(uint new_number_of_regions); 658 659 void init(); 660 661 // Create jstat counters for the policy. 662 virtual void initialize_gc_policy_counters(); 663 664 virtual HeapWord* mem_allocate_work(size_t size, 665 bool is_tlab, 666 bool* gc_overhead_limit_was_exceeded); 667 668 // This method controls how a collector handles one or more 669 // of its generations being fully allocated. 670 virtual HeapWord* satisfy_failed_allocation(size_t size, 671 bool is_tlab); 672 673 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 674 675 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 676 677 // Record the start and end of an evacuation pause. 678 void record_collection_pause_start(double start_time_sec); 679 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info); 680 681 // Record the start and end of a full collection. 682 void record_full_collection_start(); 683 void record_full_collection_end(); 684 685 // Must currently be called while the world is stopped. 686 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms); 687 688 // Record start and end of remark. 689 void record_concurrent_mark_remark_start(); 690 void record_concurrent_mark_remark_end(); 691 692 // Record start, end, and completion of cleanup. 693 void record_concurrent_mark_cleanup_start(); 694 void record_concurrent_mark_cleanup_end(int n_workers); 695 void record_concurrent_mark_cleanup_completed(); 696 697 // Records the information about the heap size for reporting in 698 // print_detailed_heap_transition 699 void record_heap_size_info_at_start(bool full); 700 701 // Print heap sizing transition (with less and more detail). 702 void print_heap_transition(); 703 void print_detailed_heap_transition(bool full = false); 704 705 void record_stop_world_start(); 706 void record_concurrent_pause(); 707 708 // Record how much space we copied during a GC. This is typically 709 // called when a GC alloc region is being retired. 710 void record_bytes_copied_during_gc(size_t bytes) { 711 _bytes_copied_during_gc += bytes; 712 } 713 714 // The amount of space we copied during a GC. 715 size_t bytes_copied_during_gc() { 716 return _bytes_copied_during_gc; 717 } 718 719 // Determine whether there are candidate regions so that the 720 // next GC should be mixed. The two action strings are used 721 // in the ergo output when the method returns true or false. 722 bool next_gc_should_be_mixed(const char* true_action_str, 723 const char* false_action_str); 724 725 // Choose a new collection set. Marks the chosen regions as being 726 // "in_collection_set", and links them together. The head and number of 727 // the collection set are available via access methods. 728 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info); 729 730 // The head of the list (via "next_in_collection_set()") representing the 731 // current collection set. 732 HeapRegion* collection_set() { return _collection_set; } 733 734 void clear_collection_set() { _collection_set = NULL; } 735 736 // Add old region "hr" to the CSet. 737 void add_old_region_to_cset(HeapRegion* hr); 738 739 // Incremental CSet Support 740 741 // The head of the incrementally built collection set. 742 HeapRegion* inc_cset_head() { return _inc_cset_head; } 743 744 // The tail of the incrementally built collection set. 745 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 746 747 // Initialize incremental collection set info. 748 void start_incremental_cset_building(); 749 750 // Perform any final calculations on the incremental CSet fields 751 // before we can use them. 752 void finalize_incremental_cset_building(); 753 754 void clear_incremental_cset() { 755 _inc_cset_head = NULL; 756 _inc_cset_tail = NULL; 757 } 758 759 // Stop adding regions to the incremental collection set 760 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 761 762 // Add information about hr to the aggregated information for the 763 // incrementally built collection set. 764 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 765 766 // Update information about hr in the aggregated information for 767 // the incrementally built collection set. 768 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 769 770 private: 771 // Update the incremental cset information when adding a region 772 // (should not be called directly). 773 void add_region_to_incremental_cset_common(HeapRegion* hr); 774 775 public: 776 // Add hr to the LHS of the incremental collection set. 777 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 778 779 // Add hr to the RHS of the incremental collection set. 780 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 781 782 #ifndef PRODUCT 783 void print_collection_set(HeapRegion* list_head, outputStream* st); 784 #endif // !PRODUCT 785 786 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 787 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 788 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 789 790 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 791 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 792 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 793 794 // This sets the initiate_conc_mark_if_possible() flag to start a 795 // new cycle, as long as we are not already in one. It's best if it 796 // is called during a safepoint when the test whether a cycle is in 797 // progress or not is stable. 798 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause); 799 800 // This is called at the very beginning of an evacuation pause (it 801 // has to be the first thing that the pause does). If 802 // initiate_conc_mark_if_possible() is true, and the concurrent 803 // marking thread has completed its work during the previous cycle, 804 // it will set during_initial_mark_pause() to so that the pause does 805 // the initial-mark work and start a marking cycle. 806 void decide_on_conc_mark_initiation(); 807 808 // If an expansion would be appropriate, because recent GC overhead had 809 // exceeded the desired limit, return an amount to expand by. 810 size_t expansion_amount(); 811 812 // Print tracing information. 813 void print_tracing_info() const; 814 815 // Print stats on young survival ratio 816 void print_yg_surv_rate_info() const; 817 818 void finished_recalculating_age_indexes(bool is_survivors) { 819 if (is_survivors) { 820 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 821 } else { 822 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 823 } 824 // do that for any other surv rate groups 825 } 826 827 size_t young_list_target_length() const { return _young_list_target_length; } 828 829 bool is_young_list_full() { 830 uint young_list_length = _g1->young_list()->length(); 831 uint young_list_target_length = _young_list_target_length; 832 return young_list_length >= young_list_target_length; 833 } 834 835 bool can_expand_young_list() { 836 uint young_list_length = _g1->young_list()->length(); 837 uint young_list_max_length = _young_list_max_length; 838 return young_list_length < young_list_max_length; 839 } 840 841 uint young_list_max_length() { 842 return _young_list_max_length; 843 } 844 845 bool gcs_are_young() { 846 return _gcs_are_young; 847 } 848 void set_gcs_are_young(bool gcs_are_young) { 849 _gcs_are_young = gcs_are_young; 850 } 851 852 bool adaptive_young_list_length() { 853 return _young_gen_sizer->adaptive_young_list_length(); 854 } 855 856 private: 857 // 858 // Survivor regions policy. 859 // 860 861 // Current tenuring threshold, set to 0 if the collector reaches the 862 // maximum amount of survivors regions. 863 uint _tenuring_threshold; 864 865 // The limit on the number of regions allocated for survivors. 866 uint _max_survivor_regions; 867 868 // For reporting purposes. 869 // The value of _heap_bytes_before_gc is also used to calculate 870 // the cost of copying. 871 872 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC 873 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC 874 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC 875 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC 876 877 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC 878 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC 879 880 // The amount of survivor regions after a collection. 881 uint _recorded_survivor_regions; 882 // List of survivor regions. 883 HeapRegion* _recorded_survivor_head; 884 HeapRegion* _recorded_survivor_tail; 885 886 ageTable _survivors_age_table; 887 888 public: 889 uint tenuring_threshold() const { return _tenuring_threshold; } 890 891 inline GCAllocPurpose 892 evacuation_destination(HeapRegion* src_region, uint age, size_t word_sz) { 893 if (age < _tenuring_threshold && src_region->is_young()) { 894 return GCAllocForSurvived; 895 } else { 896 return GCAllocForTenured; 897 } 898 } 899 900 inline bool track_object_age(GCAllocPurpose purpose) { 901 return purpose == GCAllocForSurvived; 902 } 903 904 static const uint REGIONS_UNLIMITED = (uint) -1; 905 906 uint max_regions(int purpose); 907 908 // The limit on regions for a particular purpose is reached. 909 void note_alloc_region_limit_reached(int purpose) { 910 if (purpose == GCAllocForSurvived) { 911 _tenuring_threshold = 0; 912 } 913 } 914 915 void note_start_adding_survivor_regions() { 916 _survivor_surv_rate_group->start_adding_regions(); 917 } 918 919 void note_stop_adding_survivor_regions() { 920 _survivor_surv_rate_group->stop_adding_regions(); 921 } 922 923 void record_survivor_regions(uint regions, 924 HeapRegion* head, 925 HeapRegion* tail) { 926 _recorded_survivor_regions = regions; 927 _recorded_survivor_head = head; 928 _recorded_survivor_tail = tail; 929 } 930 931 uint recorded_survivor_regions() { 932 return _recorded_survivor_regions; 933 } 934 935 void record_thread_age_table(ageTable* age_table) { 936 _survivors_age_table.merge_par(age_table); 937 } 938 939 void update_max_gc_locker_expansion(); 940 941 // Calculates survivor space parameters. 942 void update_survivors_policy(); 943 944 virtual void post_heap_initialize(); 945 }; 946 947 // This should move to some place more general... 948 949 // If we have "n" measurements, and we've kept track of their "sum" and the 950 // "sum_of_squares" of the measurements, this returns the variance of the 951 // sequence. 952 inline double variance(int n, double sum_of_squares, double sum) { 953 double n_d = (double)n; 954 double avg = sum/n_d; 955 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 956 } 957 958 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP