1 /* 2 * Copyright (c) 2001, 2010, 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 40 // Yes, this is a bit unpleasant... but it saves replicating the same thing 41 // over and over again and introducing subtle problems through small typos and 42 // cutting and pasting mistakes. The macros below introduces a number 43 // sequnce into the following two classes and the methods that access it. 44 45 #define define_num_seq(name) \ 46 private: \ 47 NumberSeq _all_##name##_times_ms; \ 48 public: \ 49 void record_##name##_time_ms(double ms) { \ 50 _all_##name##_times_ms.add(ms); \ 51 } \ 52 NumberSeq* get_##name##_seq() { \ 53 return &_all_##name##_times_ms; \ 54 } 55 56 class MainBodySummary; 57 58 class PauseSummary: public CHeapObj { 59 define_num_seq(total) 60 define_num_seq(other) 61 62 public: 63 virtual MainBodySummary* main_body_summary() { return NULL; } 64 }; 65 66 class MainBodySummary: public CHeapObj { 67 define_num_seq(satb_drain) // optional 68 define_num_seq(parallel) // parallel only 69 define_num_seq(ext_root_scan) 70 define_num_seq(mark_stack_scan) 71 define_num_seq(update_rs) 72 define_num_seq(scan_rs) 73 define_num_seq(obj_copy) 74 define_num_seq(termination) // parallel only 75 define_num_seq(parallel_other) // parallel only 76 define_num_seq(mark_closure) 77 define_num_seq(clear_ct) // parallel only 78 }; 79 80 class Summary: public PauseSummary, 81 public MainBodySummary { 82 public: 83 virtual MainBodySummary* main_body_summary() { return this; } 84 }; 85 86 class G1CollectorPolicy: public CollectorPolicy { 87 protected: 88 // The number of pauses during the execution. 89 long _n_pauses; 90 91 // either equal to the number of parallel threads, if ParallelGCThreads 92 // has been set, or 1 otherwise 93 int _parallel_gc_threads; 94 95 enum SomePrivateConstants { 96 NumPrevPausesForHeuristics = 10 97 }; 98 99 G1MMUTracker* _mmu_tracker; 100 101 void initialize_flags(); 102 103 void initialize_all() { 104 initialize_flags(); 105 initialize_size_info(); 106 initialize_perm_generation(PermGen::MarkSweepCompact); 107 } 108 109 virtual size_t default_init_heap_size() { 110 // Pick some reasonable default. 111 return 8*M; 112 } 113 114 double _cur_collection_start_sec; 115 size_t _cur_collection_pause_used_at_start_bytes; 116 size_t _cur_collection_pause_used_regions_at_start; 117 size_t _prev_collection_pause_used_at_end_bytes; 118 double _cur_collection_par_time_ms; 119 double _cur_satb_drain_time_ms; 120 double _cur_clear_ct_time_ms; 121 bool _satb_drain_time_set; 122 123 #ifndef PRODUCT 124 // Card Table Count Cache stats 125 double _min_clear_cc_time_ms; // min 126 double _max_clear_cc_time_ms; // max 127 double _cur_clear_cc_time_ms; // clearing time during current pause 128 double _cum_clear_cc_time_ms; // cummulative clearing time 129 jlong _num_cc_clears; // number of times the card count cache has been cleared 130 #endif 131 132 double _cur_CH_strong_roots_end_sec; 133 double _cur_CH_strong_roots_dur_ms; 134 double _cur_G1_strong_roots_end_sec; 135 double _cur_G1_strong_roots_dur_ms; 136 137 // Statistics for recent GC pauses. See below for how indexed. 138 TruncatedSeq* _recent_CH_strong_roots_times_ms; 139 TruncatedSeq* _recent_G1_strong_roots_times_ms; 140 TruncatedSeq* _recent_evac_times_ms; 141 // These exclude marking times. 142 TruncatedSeq* _recent_pause_times_ms; 143 TruncatedSeq* _recent_gc_times_ms; 144 145 TruncatedSeq* _recent_CS_bytes_used_before; 146 TruncatedSeq* _recent_CS_bytes_surviving; 147 148 TruncatedSeq* _recent_rs_sizes; 149 150 TruncatedSeq* _concurrent_mark_init_times_ms; 151 TruncatedSeq* _concurrent_mark_remark_times_ms; 152 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 153 154 Summary* _summary; 155 156 NumberSeq* _all_pause_times_ms; 157 NumberSeq* _all_full_gc_times_ms; 158 double _stop_world_start; 159 NumberSeq* _all_stop_world_times_ms; 160 NumberSeq* _all_yield_times_ms; 161 162 size_t _region_num_young; 163 size_t _region_num_tenured; 164 size_t _prev_region_num_young; 165 size_t _prev_region_num_tenured; 166 167 NumberSeq* _all_mod_union_times_ms; 168 169 int _aux_num; 170 NumberSeq* _all_aux_times_ms; 171 double* _cur_aux_start_times_ms; 172 double* _cur_aux_times_ms; 173 bool* _cur_aux_times_set; 174 175 double* _par_last_gc_worker_start_times_ms; 176 double* _par_last_ext_root_scan_times_ms; 177 double* _par_last_mark_stack_scan_times_ms; 178 double* _par_last_update_rs_times_ms; 179 double* _par_last_update_rs_processed_buffers; 180 double* _par_last_scan_rs_times_ms; 181 double* _par_last_obj_copy_times_ms; 182 double* _par_last_termination_times_ms; 183 double* _par_last_termination_attempts; 184 double* _par_last_gc_worker_end_times_ms; 185 double* _par_last_gc_worker_times_ms; 186 187 // indicates that we are in young GC mode 188 bool _in_young_gc_mode; 189 190 // indicates whether we are in full young or partially young GC mode 191 bool _full_young_gcs; 192 193 // if true, then it tries to dynamically adjust the length of the 194 // young list 195 bool _adaptive_young_list_length; 196 size_t _young_list_min_length; 197 size_t _young_list_target_length; 198 size_t _young_list_fixed_length; 199 200 // The max number of regions we can extend the eden by while the GC 201 // locker is active. This should be >= _young_list_target_length; 202 size_t _young_list_max_length; 203 204 size_t _young_cset_length; 205 bool _last_young_gc_full; 206 207 unsigned _full_young_pause_num; 208 unsigned _partial_young_pause_num; 209 210 bool _during_marking; 211 bool _in_marking_window; 212 bool _in_marking_window_im; 213 214 SurvRateGroup* _short_lived_surv_rate_group; 215 SurvRateGroup* _survivor_surv_rate_group; 216 // add here any more surv rate groups 217 218 double _gc_overhead_perc; 219 220 bool during_marking() { 221 return _during_marking; 222 } 223 224 // <NEW PREDICTION> 225 226 private: 227 enum PredictionConstants { 228 TruncatedSeqLength = 10 229 }; 230 231 TruncatedSeq* _alloc_rate_ms_seq; 232 double _prev_collection_pause_end_ms; 233 234 TruncatedSeq* _pending_card_diff_seq; 235 TruncatedSeq* _rs_length_diff_seq; 236 TruncatedSeq* _cost_per_card_ms_seq; 237 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq; 238 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq; 239 TruncatedSeq* _cost_per_entry_ms_seq; 240 TruncatedSeq* _partially_young_cost_per_entry_ms_seq; 241 TruncatedSeq* _cost_per_byte_ms_seq; 242 TruncatedSeq* _constant_other_time_ms_seq; 243 TruncatedSeq* _young_other_cost_per_region_ms_seq; 244 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 245 246 TruncatedSeq* _pending_cards_seq; 247 TruncatedSeq* _scanned_cards_seq; 248 TruncatedSeq* _rs_lengths_seq; 249 250 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 251 252 TruncatedSeq* _young_gc_eff_seq; 253 254 TruncatedSeq* _max_conc_overhead_seq; 255 256 size_t _recorded_young_regions; 257 size_t _recorded_non_young_regions; 258 size_t _recorded_region_num; 259 260 size_t _free_regions_at_end_of_collection; 261 262 size_t _recorded_rs_lengths; 263 size_t _max_rs_lengths; 264 265 size_t _recorded_marked_bytes; 266 size_t _recorded_young_bytes; 267 268 size_t _predicted_pending_cards; 269 size_t _predicted_cards_scanned; 270 size_t _predicted_rs_lengths; 271 size_t _predicted_bytes_to_copy; 272 273 double _predicted_survival_ratio; 274 double _predicted_rs_update_time_ms; 275 double _predicted_rs_scan_time_ms; 276 double _predicted_object_copy_time_ms; 277 double _predicted_constant_other_time_ms; 278 double _predicted_young_other_time_ms; 279 double _predicted_non_young_other_time_ms; 280 double _predicted_pause_time_ms; 281 282 double _vtime_diff_ms; 283 284 double _recorded_young_free_cset_time_ms; 285 double _recorded_non_young_free_cset_time_ms; 286 287 double _sigma; 288 double _expensive_region_limit_ms; 289 290 size_t _rs_lengths_prediction; 291 292 size_t _known_garbage_bytes; 293 double _known_garbage_ratio; 294 295 double sigma() { 296 return _sigma; 297 } 298 299 // A function that prevents us putting too much stock in small sample 300 // sets. Returns a number between 2.0 and 1.0, depending on the number 301 // of samples. 5 or more samples yields one; fewer scales linearly from 302 // 2.0 at 1 sample to 1.0 at 5. 303 double confidence_factor(int samples) { 304 if (samples > 4) return 1.0; 305 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 306 } 307 308 double get_new_neg_prediction(TruncatedSeq* seq) { 309 return seq->davg() - sigma() * seq->dsd(); 310 } 311 312 #ifndef PRODUCT 313 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 314 #endif // PRODUCT 315 316 void adjust_concurrent_refinement(double update_rs_time, 317 double update_rs_processed_buffers, 318 double goal_ms); 319 320 protected: 321 double _pause_time_target_ms; 322 double _recorded_young_cset_choice_time_ms; 323 double _recorded_non_young_cset_choice_time_ms; 324 bool _within_target; 325 size_t _pending_cards; 326 size_t _max_pending_cards; 327 328 public: 329 330 void set_region_short_lived(HeapRegion* hr) { 331 hr->install_surv_rate_group(_short_lived_surv_rate_group); 332 } 333 334 void set_region_survivors(HeapRegion* hr) { 335 hr->install_surv_rate_group(_survivor_surv_rate_group); 336 } 337 338 #ifndef PRODUCT 339 bool verify_young_ages(); 340 #endif // PRODUCT 341 342 double get_new_prediction(TruncatedSeq* seq) { 343 return MAX2(seq->davg() + sigma() * seq->dsd(), 344 seq->davg() * confidence_factor(seq->num())); 345 } 346 347 size_t young_cset_length() { 348 return _young_cset_length; 349 } 350 351 void record_max_rs_lengths(size_t rs_lengths) { 352 _max_rs_lengths = rs_lengths; 353 } 354 355 size_t predict_pending_card_diff() { 356 double prediction = get_new_neg_prediction(_pending_card_diff_seq); 357 if (prediction < 0.00001) 358 return 0; 359 else 360 return (size_t) prediction; 361 } 362 363 size_t predict_pending_cards() { 364 size_t max_pending_card_num = _g1->max_pending_card_num(); 365 size_t diff = predict_pending_card_diff(); 366 size_t prediction; 367 if (diff > max_pending_card_num) 368 prediction = max_pending_card_num; 369 else 370 prediction = max_pending_card_num - diff; 371 372 return prediction; 373 } 374 375 size_t predict_rs_length_diff() { 376 return (size_t) get_new_prediction(_rs_length_diff_seq); 377 } 378 379 double predict_alloc_rate_ms() { 380 return get_new_prediction(_alloc_rate_ms_seq); 381 } 382 383 double predict_cost_per_card_ms() { 384 return get_new_prediction(_cost_per_card_ms_seq); 385 } 386 387 double predict_rs_update_time_ms(size_t pending_cards) { 388 return (double) pending_cards * predict_cost_per_card_ms(); 389 } 390 391 double predict_fully_young_cards_per_entry_ratio() { 392 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq); 393 } 394 395 double predict_partially_young_cards_per_entry_ratio() { 396 if (_partially_young_cards_per_entry_ratio_seq->num() < 2) 397 return predict_fully_young_cards_per_entry_ratio(); 398 else 399 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq); 400 } 401 402 size_t predict_young_card_num(size_t rs_length) { 403 return (size_t) ((double) rs_length * 404 predict_fully_young_cards_per_entry_ratio()); 405 } 406 407 size_t predict_non_young_card_num(size_t rs_length) { 408 return (size_t) ((double) rs_length * 409 predict_partially_young_cards_per_entry_ratio()); 410 } 411 412 double predict_rs_scan_time_ms(size_t card_num) { 413 if (full_young_gcs()) 414 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 415 else 416 return predict_partially_young_rs_scan_time_ms(card_num); 417 } 418 419 double predict_partially_young_rs_scan_time_ms(size_t card_num) { 420 if (_partially_young_cost_per_entry_ms_seq->num() < 3) 421 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 422 else 423 return (double) card_num * 424 get_new_prediction(_partially_young_cost_per_entry_ms_seq); 425 } 426 427 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 428 if (_cost_per_byte_ms_during_cm_seq->num() < 3) 429 return 1.1 * (double) bytes_to_copy * 430 get_new_prediction(_cost_per_byte_ms_seq); 431 else 432 return (double) bytes_to_copy * 433 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 434 } 435 436 double predict_object_copy_time_ms(size_t bytes_to_copy) { 437 if (_in_marking_window && !_in_marking_window_im) 438 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 439 else 440 return (double) bytes_to_copy * 441 get_new_prediction(_cost_per_byte_ms_seq); 442 } 443 444 double predict_constant_other_time_ms() { 445 return get_new_prediction(_constant_other_time_ms_seq); 446 } 447 448 double predict_young_other_time_ms(size_t young_num) { 449 return 450 (double) young_num * 451 get_new_prediction(_young_other_cost_per_region_ms_seq); 452 } 453 454 double predict_non_young_other_time_ms(size_t non_young_num) { 455 return 456 (double) non_young_num * 457 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 458 } 459 460 void check_if_region_is_too_expensive(double predicted_time_ms); 461 462 double predict_young_collection_elapsed_time_ms(size_t adjustment); 463 double predict_base_elapsed_time_ms(size_t pending_cards); 464 double predict_base_elapsed_time_ms(size_t pending_cards, 465 size_t scanned_cards); 466 size_t predict_bytes_to_copy(HeapRegion* hr); 467 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); 468 469 // for use by: calculate_young_list_target_length(rs_length) 470 bool predict_will_fit(size_t young_region_num, 471 double base_time_ms, 472 size_t init_free_regions, 473 double target_pause_time_ms); 474 475 void start_recording_regions(); 476 void record_cset_region_info(HeapRegion* hr, bool young); 477 void record_non_young_cset_region(HeapRegion* hr); 478 479 void set_recorded_young_regions(size_t n_regions); 480 void set_recorded_young_bytes(size_t bytes); 481 void set_recorded_rs_lengths(size_t rs_lengths); 482 void set_predicted_bytes_to_copy(size_t bytes); 483 484 void end_recording_regions(); 485 486 void record_vtime_diff_ms(double vtime_diff_ms) { 487 _vtime_diff_ms = vtime_diff_ms; 488 } 489 490 void record_young_free_cset_time_ms(double time_ms) { 491 _recorded_young_free_cset_time_ms = time_ms; 492 } 493 494 void record_non_young_free_cset_time_ms(double time_ms) { 495 _recorded_non_young_free_cset_time_ms = time_ms; 496 } 497 498 double predict_young_gc_eff() { 499 return get_new_neg_prediction(_young_gc_eff_seq); 500 } 501 502 double predict_survivor_regions_evac_time(); 503 504 // </NEW PREDICTION> 505 506 public: 507 void cset_regions_freed() { 508 bool propagate = _last_young_gc_full && !_in_marking_window; 509 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 510 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 511 // also call it on any more surv rate groups 512 } 513 514 void set_known_garbage_bytes(size_t known_garbage_bytes) { 515 _known_garbage_bytes = known_garbage_bytes; 516 size_t heap_bytes = _g1->capacity(); 517 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes; 518 } 519 520 void decrease_known_garbage_bytes(size_t known_garbage_bytes) { 521 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" ); 522 523 _known_garbage_bytes -= known_garbage_bytes; 524 size_t heap_bytes = _g1->capacity(); 525 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes; 526 } 527 528 G1MMUTracker* mmu_tracker() { 529 return _mmu_tracker; 530 } 531 532 double max_pause_time_ms() { 533 return _mmu_tracker->max_gc_time() * 1000.0; 534 } 535 536 double predict_init_time_ms() { 537 return get_new_prediction(_concurrent_mark_init_times_ms); 538 } 539 540 double predict_remark_time_ms() { 541 return get_new_prediction(_concurrent_mark_remark_times_ms); 542 } 543 544 double predict_cleanup_time_ms() { 545 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 546 } 547 548 // Returns an estimate of the survival rate of the region at yg-age 549 // "yg_age". 550 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 551 TruncatedSeq* seq = surv_rate_group->get_seq(age); 552 if (seq->num() == 0) 553 gclog_or_tty->print("BARF! age is %d", age); 554 guarantee( seq->num() > 0, "invariant" ); 555 double pred = get_new_prediction(seq); 556 if (pred > 1.0) 557 pred = 1.0; 558 return pred; 559 } 560 561 double predict_yg_surv_rate(int age) { 562 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 563 } 564 565 double accum_yg_surv_rate_pred(int age) { 566 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 567 } 568 569 protected: 570 void print_stats(int level, const char* str, double value); 571 void print_stats(int level, const char* str, int value); 572 573 void print_par_stats(int level, const char* str, double* data); 574 void print_par_sizes(int level, const char* str, double* data); 575 576 void check_other_times(int level, 577 NumberSeq* other_times_ms, 578 NumberSeq* calc_other_times_ms) const; 579 580 void print_summary (PauseSummary* stats) const; 581 582 void print_summary (int level, const char* str, NumberSeq* seq) const; 583 void print_summary_sd (int level, const char* str, NumberSeq* seq) const; 584 585 double avg_value (double* data); 586 double max_value (double* data); 587 double sum_of_values (double* data); 588 double max_sum (double* data1, double* data2); 589 590 int _last_satb_drain_processed_buffers; 591 int _last_update_rs_processed_buffers; 592 double _last_pause_time_ms; 593 594 size_t _bytes_in_to_space_before_gc; 595 size_t _bytes_in_to_space_after_gc; 596 size_t bytes_in_to_space_during_gc() { 597 return 598 _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc; 599 } 600 size_t _bytes_in_collection_set_before_gc; 601 // Used to count used bytes in CS. 602 friend class CountCSClosure; 603 604 // Statistics kept per GC stoppage, pause or full. 605 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 606 607 // We track markings. 608 int _num_markings; 609 double _mark_thread_startup_sec; // Time at startup of marking thread 610 611 // Add a new GC of the given duration and end time to the record. 612 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 613 614 // The head of the list (via "next_in_collection_set()") representing the 615 // current collection set. Set from the incrementally built collection 616 // set at the start of the pause. 617 HeapRegion* _collection_set; 618 619 // The number of regions in the collection set. Set from the incrementally 620 // built collection set at the start of an evacuation pause. 621 size_t _collection_set_size; 622 623 // The number of bytes in the collection set before the pause. Set from 624 // the incrementally built collection set at the start of an evacuation 625 // pause. 626 size_t _collection_set_bytes_used_before; 627 628 // The associated information that is maintained while the incremental 629 // collection set is being built with young regions. Used to populate 630 // the recorded info for the evacuation pause. 631 632 enum CSetBuildType { 633 Active, // We are actively building the collection set 634 Inactive // We are not actively building the collection set 635 }; 636 637 CSetBuildType _inc_cset_build_state; 638 639 // The head of the incrementally built collection set. 640 HeapRegion* _inc_cset_head; 641 642 // The tail of the incrementally built collection set. 643 HeapRegion* _inc_cset_tail; 644 645 // The number of regions in the incrementally built collection set. 646 // Used to set _collection_set_size at the start of an evacuation 647 // pause. 648 size_t _inc_cset_size; 649 650 // Used as the index in the surving young words structure 651 // which tracks the amount of space, for each young region, 652 // that survives the pause. 653 size_t _inc_cset_young_index; 654 655 // The number of bytes in the incrementally built collection set. 656 // Used to set _collection_set_bytes_used_before at the start of 657 // an evacuation pause. 658 size_t _inc_cset_bytes_used_before; 659 660 // Used to record the highest end of heap region in collection set 661 HeapWord* _inc_cset_max_finger; 662 663 // The number of recorded used bytes in the young regions 664 // of the collection set. This is the sum of the used() bytes 665 // of retired young regions in the collection set. 666 size_t _inc_cset_recorded_young_bytes; 667 668 // The RSet lengths recorded for regions in the collection set 669 // (updated by the periodic sampling of the regions in the 670 // young list/collection set). 671 size_t _inc_cset_recorded_rs_lengths; 672 673 // The predicted elapsed time it will take to collect the regions 674 // in the collection set (updated by the periodic sampling of the 675 // regions in the young list/collection set). 676 double _inc_cset_predicted_elapsed_time_ms; 677 678 // The predicted bytes to copy for the regions in the collection 679 // set (updated by the periodic sampling of the regions in the 680 // young list/collection set). 681 size_t _inc_cset_predicted_bytes_to_copy; 682 683 // Info about marking. 684 int _n_marks; // Sticky at 2, so we know when we've done at least 2. 685 686 // The number of collection pauses at the end of the last mark. 687 size_t _n_pauses_at_mark_end; 688 689 // Stash a pointer to the g1 heap. 690 G1CollectedHeap* _g1; 691 692 // The average time in ms per collection pause, averaged over recent pauses. 693 double recent_avg_time_for_pauses_ms(); 694 695 // The average time in ms for processing CollectedHeap strong roots, per 696 // collection pause, averaged over recent pauses. 697 double recent_avg_time_for_CH_strong_ms(); 698 699 // The average time in ms for processing the G1 remembered set, per 700 // pause, averaged over recent pauses. 701 double recent_avg_time_for_G1_strong_ms(); 702 703 // The average time in ms for "evacuating followers", per pause, averaged 704 // over recent pauses. 705 double recent_avg_time_for_evac_ms(); 706 707 // The number of "recent" GCs recorded in the number sequences 708 int number_of_recent_gcs(); 709 710 // The average survival ratio, computed by the total number of bytes 711 // suriviving / total number of bytes before collection over the last 712 // several recent pauses. 713 double recent_avg_survival_fraction(); 714 // The survival fraction of the most recent pause; if there have been no 715 // pauses, returns 1.0. 716 double last_survival_fraction(); 717 718 // Returns a "conservative" estimate of the recent survival rate, i.e., 719 // one that may be higher than "recent_avg_survival_fraction". 720 // This is conservative in several ways: 721 // If there have been few pauses, it will assume a potential high 722 // variance, and err on the side of caution. 723 // It puts a lower bound (currently 0.1) on the value it will return. 724 // To try to detect phase changes, if the most recent pause ("latest") has a 725 // higher-than average ("avg") survival rate, it returns that rate. 726 // "work" version is a utility function; young is restricted to young regions. 727 double conservative_avg_survival_fraction_work(double avg, 728 double latest); 729 730 // The arguments are the two sequences that keep track of the number of bytes 731 // surviving and the total number of bytes before collection, resp., 732 // over the last evereal recent pauses 733 // Returns the survival rate for the category in the most recent pause. 734 // If there have been no pauses, returns 1.0. 735 double last_survival_fraction_work(TruncatedSeq* surviving, 736 TruncatedSeq* before); 737 738 // The arguments are the two sequences that keep track of the number of bytes 739 // surviving and the total number of bytes before collection, resp., 740 // over the last several recent pauses 741 // Returns the average survival ration over the last several recent pauses 742 // If there have been no pauses, return 1.0 743 double recent_avg_survival_fraction_work(TruncatedSeq* surviving, 744 TruncatedSeq* before); 745 746 double conservative_avg_survival_fraction() { 747 double avg = recent_avg_survival_fraction(); 748 double latest = last_survival_fraction(); 749 return conservative_avg_survival_fraction_work(avg, latest); 750 } 751 752 // The ratio of gc time to elapsed time, computed over recent pauses. 753 double _recent_avg_pause_time_ratio; 754 755 double recent_avg_pause_time_ratio() { 756 return _recent_avg_pause_time_ratio; 757 } 758 759 // Number of pauses between concurrent marking. 760 size_t _pauses_btwn_concurrent_mark; 761 762 size_t _n_marks_since_last_pause; 763 764 // At the end of a pause we check the heap occupancy and we decide 765 // whether we will start a marking cycle during the next pause. If 766 // we decide that we want to do that, we will set this parameter to 767 // true. So, this parameter will stay true between the end of a 768 // pause and the beginning of a subsequent pause (not necessarily 769 // the next one, see the comments on the next field) when we decide 770 // that we will indeed start a marking cycle and do the initial-mark 771 // work. 772 volatile bool _initiate_conc_mark_if_possible; 773 774 // If initiate_conc_mark_if_possible() is set at the beginning of a 775 // pause, it is a suggestion that the pause should start a marking 776 // cycle by doing the initial-mark work. However, it is possible 777 // that the concurrent marking thread is still finishing up the 778 // previous marking cycle (e.g., clearing the next marking 779 // bitmap). If that is the case we cannot start a new cycle and 780 // we'll have to wait for the concurrent marking thread to finish 781 // what it is doing. In this case we will postpone the marking cycle 782 // initiation decision for the next pause. When we eventually decide 783 // to start a cycle, we will set _during_initial_mark_pause which 784 // will stay true until the end of the initial-mark pause and it's 785 // the condition that indicates that a pause is doing the 786 // initial-mark work. 787 volatile bool _during_initial_mark_pause; 788 789 bool _should_revert_to_full_young_gcs; 790 bool _last_full_young_gc; 791 792 // This set of variables tracks the collector efficiency, in order to 793 // determine whether we should initiate a new marking. 794 double _cur_mark_stop_world_time_ms; 795 double _mark_init_start_sec; 796 double _mark_remark_start_sec; 797 double _mark_cleanup_start_sec; 798 double _mark_closure_time_ms; 799 800 void calculate_young_list_min_length(); 801 void calculate_young_list_target_length(); 802 void calculate_young_list_target_length(size_t rs_lengths); 803 804 public: 805 806 G1CollectorPolicy(); 807 808 virtual G1CollectorPolicy* as_g1_policy() { return this; } 809 810 virtual CollectorPolicy::Name kind() { 811 return CollectorPolicy::G1CollectorPolicyKind; 812 } 813 814 void check_prediction_validity(); 815 816 size_t bytes_in_collection_set() { 817 return _bytes_in_collection_set_before_gc; 818 } 819 820 size_t bytes_in_to_space() { 821 return bytes_in_to_space_during_gc(); 822 } 823 824 unsigned calc_gc_alloc_time_stamp() { 825 return _all_pause_times_ms->num() + 1; 826 } 827 828 protected: 829 830 // Count the number of bytes used in the CS. 831 void count_CS_bytes_used(); 832 833 // Together these do the base cleanup-recording work. Subclasses might 834 // want to put something between them. 835 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes, 836 size_t max_live_bytes); 837 void record_concurrent_mark_cleanup_end_work2(); 838 839 public: 840 841 virtual void init(); 842 843 // Create jstat counters for the policy. 844 virtual void initialize_gc_policy_counters(); 845 846 virtual HeapWord* mem_allocate_work(size_t size, 847 bool is_tlab, 848 bool* gc_overhead_limit_was_exceeded); 849 850 // This method controls how a collector handles one or more 851 // of its generations being fully allocated. 852 virtual HeapWord* satisfy_failed_allocation(size_t size, 853 bool is_tlab); 854 855 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 856 857 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; } 858 859 // The number of collection pauses so far. 860 long n_pauses() const { return _n_pauses; } 861 862 // Update the heuristic info to record a collection pause of the given 863 // start time, where the given number of bytes were used at the start. 864 // This may involve changing the desired size of a collection set. 865 866 virtual void record_stop_world_start(); 867 868 virtual void record_collection_pause_start(double start_time_sec, 869 size_t start_used); 870 871 // Must currently be called while the world is stopped. 872 virtual void record_concurrent_mark_init_start(); 873 virtual void record_concurrent_mark_init_end(); 874 void record_concurrent_mark_init_end_pre(double 875 mark_init_elapsed_time_ms); 876 877 void record_mark_closure_time(double mark_closure_time_ms); 878 879 virtual void record_concurrent_mark_remark_start(); 880 virtual void record_concurrent_mark_remark_end(); 881 882 virtual void record_concurrent_mark_cleanup_start(); 883 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes, 884 size_t max_live_bytes); 885 virtual void record_concurrent_mark_cleanup_completed(); 886 887 virtual void record_concurrent_pause(); 888 virtual void record_concurrent_pause_end(); 889 890 virtual void record_collection_pause_end_CH_strong_roots(); 891 virtual void record_collection_pause_end_G1_strong_roots(); 892 893 virtual void record_collection_pause_end(); 894 void print_heap_transition(); 895 896 // Record the fact that a full collection occurred. 897 virtual void record_full_collection_start(); 898 virtual void record_full_collection_end(); 899 900 void record_gc_worker_start_time(int worker_i, double ms) { 901 _par_last_gc_worker_start_times_ms[worker_i] = ms; 902 } 903 904 void record_ext_root_scan_time(int worker_i, double ms) { 905 _par_last_ext_root_scan_times_ms[worker_i] = ms; 906 } 907 908 void record_mark_stack_scan_time(int worker_i, double ms) { 909 _par_last_mark_stack_scan_times_ms[worker_i] = ms; 910 } 911 912 void record_satb_drain_time(double ms) { 913 _cur_satb_drain_time_ms = ms; 914 _satb_drain_time_set = true; 915 } 916 917 void record_satb_drain_processed_buffers (int processed_buffers) { 918 _last_satb_drain_processed_buffers = processed_buffers; 919 } 920 921 void record_mod_union_time(double ms) { 922 _all_mod_union_times_ms->add(ms); 923 } 924 925 void record_update_rs_time(int thread, double ms) { 926 _par_last_update_rs_times_ms[thread] = ms; 927 } 928 929 void record_update_rs_processed_buffers (int thread, 930 double processed_buffers) { 931 _par_last_update_rs_processed_buffers[thread] = processed_buffers; 932 } 933 934 void record_scan_rs_time(int thread, double ms) { 935 _par_last_scan_rs_times_ms[thread] = ms; 936 } 937 938 void reset_obj_copy_time(int thread) { 939 _par_last_obj_copy_times_ms[thread] = 0.0; 940 } 941 942 void reset_obj_copy_time() { 943 reset_obj_copy_time(0); 944 } 945 946 void record_obj_copy_time(int thread, double ms) { 947 _par_last_obj_copy_times_ms[thread] += ms; 948 } 949 950 void record_termination(int thread, double ms, size_t attempts) { 951 _par_last_termination_times_ms[thread] = ms; 952 _par_last_termination_attempts[thread] = (double) attempts; 953 } 954 955 void record_gc_worker_end_time(int worker_i, double ms) { 956 _par_last_gc_worker_end_times_ms[worker_i] = ms; 957 } 958 959 void record_pause_time_ms(double ms) { 960 _last_pause_time_ms = ms; 961 } 962 963 void record_clear_ct_time(double ms) { 964 _cur_clear_ct_time_ms = ms; 965 } 966 967 void record_par_time(double ms) { 968 _cur_collection_par_time_ms = ms; 969 } 970 971 void record_aux_start_time(int i) { 972 guarantee(i < _aux_num, "should be within range"); 973 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0; 974 } 975 976 void record_aux_end_time(int i) { 977 guarantee(i < _aux_num, "should be within range"); 978 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i]; 979 _cur_aux_times_set[i] = true; 980 _cur_aux_times_ms[i] += ms; 981 } 982 983 #ifndef PRODUCT 984 void record_cc_clear_time(double ms) { 985 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms) 986 _min_clear_cc_time_ms = ms; 987 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms) 988 _max_clear_cc_time_ms = ms; 989 _cur_clear_cc_time_ms = ms; 990 _cum_clear_cc_time_ms += ms; 991 _num_cc_clears++; 992 } 993 #endif 994 995 // Record the fact that "bytes" bytes allocated in a region. 996 void record_before_bytes(size_t bytes); 997 void record_after_bytes(size_t bytes); 998 999 // Choose a new collection set. Marks the chosen regions as being 1000 // "in_collection_set", and links them together. The head and number of 1001 // the collection set are available via access methods. 1002 virtual void choose_collection_set(double target_pause_time_ms) = 0; 1003 1004 // The head of the list (via "next_in_collection_set()") representing the 1005 // current collection set. 1006 HeapRegion* collection_set() { return _collection_set; } 1007 1008 void clear_collection_set() { _collection_set = NULL; } 1009 1010 // The number of elements in the current collection set. 1011 size_t collection_set_size() { return _collection_set_size; } 1012 1013 // Add "hr" to the CS. 1014 void add_to_collection_set(HeapRegion* hr); 1015 1016 // Incremental CSet Support 1017 1018 // The head of the incrementally built collection set. 1019 HeapRegion* inc_cset_head() { return _inc_cset_head; } 1020 1021 // The tail of the incrementally built collection set. 1022 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 1023 1024 // The number of elements in the incrementally built collection set. 1025 size_t inc_cset_size() { return _inc_cset_size; } 1026 1027 // Initialize incremental collection set info. 1028 void start_incremental_cset_building(); 1029 1030 void clear_incremental_cset() { 1031 _inc_cset_head = NULL; 1032 _inc_cset_tail = NULL; 1033 } 1034 1035 // Stop adding regions to the incremental collection set 1036 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 1037 1038 // Add/remove information about hr to the aggregated information 1039 // for the incrementally built collection set. 1040 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 1041 void remove_from_incremental_cset_info(HeapRegion* hr); 1042 1043 // Update information about hr in the aggregated information for 1044 // the incrementally built collection set. 1045 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 1046 1047 private: 1048 // Update the incremental cset information when adding a region 1049 // (should not be called directly). 1050 void add_region_to_incremental_cset_common(HeapRegion* hr); 1051 1052 public: 1053 // Add hr to the LHS of the incremental collection set. 1054 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 1055 1056 // Add hr to the RHS of the incremental collection set. 1057 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 1058 1059 #ifndef PRODUCT 1060 void print_collection_set(HeapRegion* list_head, outputStream* st); 1061 #endif // !PRODUCT 1062 1063 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 1064 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 1065 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 1066 1067 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 1068 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 1069 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 1070 1071 // This sets the initiate_conc_mark_if_possible() flag to start a 1072 // new cycle, as long as we are not already in one. It's best if it 1073 // is called during a safepoint when the test whether a cycle is in 1074 // progress or not is stable. 1075 bool force_initial_mark_if_outside_cycle(); 1076 1077 // This is called at the very beginning of an evacuation pause (it 1078 // has to be the first thing that the pause does). If 1079 // initiate_conc_mark_if_possible() is true, and the concurrent 1080 // marking thread has completed its work during the previous cycle, 1081 // it will set during_initial_mark_pause() to so that the pause does 1082 // the initial-mark work and start a marking cycle. 1083 void decide_on_conc_mark_initiation(); 1084 1085 // If an expansion would be appropriate, because recent GC overhead had 1086 // exceeded the desired limit, return an amount to expand by. 1087 virtual size_t expansion_amount(); 1088 1089 // note start of mark thread 1090 void note_start_of_mark_thread(); 1091 1092 // The marked bytes of the "r" has changed; reclassify it's desirability 1093 // for marking. Also asserts that "r" is eligible for a CS. 1094 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0; 1095 1096 #ifndef PRODUCT 1097 // Check any appropriate marked bytes info, asserting false if 1098 // something's wrong, else returning "true". 1099 virtual bool assertMarkedBytesDataOK() = 0; 1100 #endif 1101 1102 // Print tracing information. 1103 void print_tracing_info() const; 1104 1105 // Print stats on young survival ratio 1106 void print_yg_surv_rate_info() const; 1107 1108 void finished_recalculating_age_indexes(bool is_survivors) { 1109 if (is_survivors) { 1110 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 1111 } else { 1112 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 1113 } 1114 // do that for any other surv rate groups 1115 } 1116 1117 bool is_young_list_full() { 1118 size_t young_list_length = _g1->young_list()->length(); 1119 size_t young_list_target_length = _young_list_target_length; 1120 if (G1FixedEdenSize) { 1121 young_list_target_length -= _max_survivor_regions; 1122 } 1123 return young_list_length >= young_list_target_length; 1124 } 1125 1126 bool can_expand_young_list() { 1127 size_t young_list_length = _g1->young_list()->length(); 1128 size_t young_list_max_length = _young_list_max_length; 1129 if (G1FixedEdenSize) { 1130 young_list_max_length -= _max_survivor_regions; 1131 } 1132 return young_list_length < young_list_max_length; 1133 } 1134 1135 void update_region_num(bool young); 1136 1137 bool in_young_gc_mode() { 1138 return _in_young_gc_mode; 1139 } 1140 void set_in_young_gc_mode(bool in_young_gc_mode) { 1141 _in_young_gc_mode = in_young_gc_mode; 1142 } 1143 1144 bool full_young_gcs() { 1145 return _full_young_gcs; 1146 } 1147 void set_full_young_gcs(bool full_young_gcs) { 1148 _full_young_gcs = full_young_gcs; 1149 } 1150 1151 bool adaptive_young_list_length() { 1152 return _adaptive_young_list_length; 1153 } 1154 void set_adaptive_young_list_length(bool adaptive_young_list_length) { 1155 _adaptive_young_list_length = adaptive_young_list_length; 1156 } 1157 1158 inline double get_gc_eff_factor() { 1159 double ratio = _known_garbage_ratio; 1160 1161 double square = ratio * ratio; 1162 // square = square * square; 1163 double ret = square * 9.0 + 1.0; 1164 #if 0 1165 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret); 1166 #endif // 0 1167 guarantee(0.0 <= ret && ret < 10.0, "invariant!"); 1168 return ret; 1169 } 1170 1171 // 1172 // Survivor regions policy. 1173 // 1174 protected: 1175 1176 // Current tenuring threshold, set to 0 if the collector reaches the 1177 // maximum amount of suvivors regions. 1178 int _tenuring_threshold; 1179 1180 // The limit on the number of regions allocated for survivors. 1181 size_t _max_survivor_regions; 1182 1183 // For reporting purposes. 1184 size_t _eden_bytes_before_gc; 1185 size_t _survivor_bytes_before_gc; 1186 size_t _capacity_before_gc; 1187 1188 // The amount of survor regions after a collection. 1189 size_t _recorded_survivor_regions; 1190 // List of survivor regions. 1191 HeapRegion* _recorded_survivor_head; 1192 HeapRegion* _recorded_survivor_tail; 1193 1194 ageTable _survivors_age_table; 1195 1196 public: 1197 1198 inline GCAllocPurpose 1199 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) { 1200 if (age < _tenuring_threshold && src_region->is_young()) { 1201 return GCAllocForSurvived; 1202 } else { 1203 return GCAllocForTenured; 1204 } 1205 } 1206 1207 inline bool track_object_age(GCAllocPurpose purpose) { 1208 return purpose == GCAllocForSurvived; 1209 } 1210 1211 inline GCAllocPurpose alternative_purpose(int purpose) { 1212 return GCAllocForTenured; 1213 } 1214 1215 static const size_t REGIONS_UNLIMITED = ~(size_t)0; 1216 1217 size_t max_regions(int purpose); 1218 1219 // The limit on regions for a particular purpose is reached. 1220 void note_alloc_region_limit_reached(int purpose) { 1221 if (purpose == GCAllocForSurvived) { 1222 _tenuring_threshold = 0; 1223 } 1224 } 1225 1226 void note_start_adding_survivor_regions() { 1227 _survivor_surv_rate_group->start_adding_regions(); 1228 } 1229 1230 void note_stop_adding_survivor_regions() { 1231 _survivor_surv_rate_group->stop_adding_regions(); 1232 } 1233 1234 void record_survivor_regions(size_t regions, 1235 HeapRegion* head, 1236 HeapRegion* tail) { 1237 _recorded_survivor_regions = regions; 1238 _recorded_survivor_head = head; 1239 _recorded_survivor_tail = tail; 1240 } 1241 1242 size_t recorded_survivor_regions() { 1243 return _recorded_survivor_regions; 1244 } 1245 1246 void record_thread_age_table(ageTable* age_table) 1247 { 1248 _survivors_age_table.merge_par(age_table); 1249 } 1250 1251 void calculate_max_gc_locker_expansion(); 1252 1253 // Calculates survivor space parameters. 1254 void calculate_survivors_policy(); 1255 1256 }; 1257 1258 // This encapsulates a particular strategy for a g1 Collector. 1259 // 1260 // Start a concurrent mark when our heap size is n bytes 1261 // greater then our heap size was at the last concurrent 1262 // mark. Where n is a function of the CMSTriggerRatio 1263 // and the MinHeapFreeRatio. 1264 // 1265 // Start a g1 collection pause when we have allocated the 1266 // average number of bytes currently being freed in 1267 // a collection, but only if it is at least one region 1268 // full 1269 // 1270 // Resize Heap based on desired 1271 // allocation space, where desired allocation space is 1272 // a function of survival rate and desired future to size. 1273 // 1274 // Choose collection set by first picking all older regions 1275 // which have a survival rate which beats our projected young 1276 // survival rate. Then fill out the number of needed regions 1277 // with young regions. 1278 1279 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy { 1280 CollectionSetChooser* _collectionSetChooser; 1281 // If the estimated is less then desirable, resize if possible. 1282 void expand_if_possible(size_t numRegions); 1283 1284 virtual void choose_collection_set(double target_pause_time_ms); 1285 virtual void record_collection_pause_start(double start_time_sec, 1286 size_t start_used); 1287 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes, 1288 size_t max_live_bytes); 1289 virtual void record_full_collection_end(); 1290 1291 public: 1292 G1CollectorPolicy_BestRegionsFirst() { 1293 _collectionSetChooser = new CollectionSetChooser(); 1294 } 1295 void record_collection_pause_end(); 1296 // This is not needed any more, after the CSet choosing code was 1297 // changed to use the pause prediction work. But let's leave the 1298 // hook in just in case. 1299 void note_change_in_marked_bytes(HeapRegion* r) { } 1300 #ifndef PRODUCT 1301 bool assertMarkedBytesDataOK(); 1302 #endif 1303 }; 1304 1305 // This should move to some place more general... 1306 1307 // If we have "n" measurements, and we've kept track of their "sum" and the 1308 // "sum_of_squares" of the measurements, this returns the variance of the 1309 // sequence. 1310 inline double variance(int n, double sum_of_squares, double sum) { 1311 double n_d = (double)n; 1312 double avg = sum/n_d; 1313 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 1314 } 1315 1316 // Local Variables: *** 1317 // c-indentation-style: gnu *** 1318 // End: *** 1319 1320 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP