1 /* 2 * Copyright (c) 2001, 2012, 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(root_region_scan_wait) 68 define_num_seq(parallel) // parallel only 69 define_num_seq(ext_root_scan) 70 define_num_seq(satb_filtering) 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(clear_ct) 77 }; 78 79 class Summary: public PauseSummary, 80 public MainBodySummary { 81 public: 82 virtual MainBodySummary* main_body_summary() { return this; } 83 }; 84 85 // There are three command line options related to the young gen size: 86 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is 87 // just a short form for NewSize==MaxNewSize). G1 will use its internal 88 // heuristics to calculate the actual young gen size, so these options 89 // basically only limit the range within which G1 can pick a young gen 90 // size. Also, these are general options taking byte sizes. G1 will 91 // internally work with a number of regions instead. So, some rounding 92 // will occur. 93 // 94 // If nothing related to the the young gen size is set on the command 95 // line we should allow the young gen to be between 96 // G1DefaultMinNewGenPercent and G1DefaultMaxNewGenPercent of the 97 // heap size. This means that every time the heap size changes the 98 // limits for the young gen size will be updated. 99 // 100 // If only -XX:NewSize is set we should use the specified value as the 101 // minimum size for young gen. Still using G1DefaultMaxNewGenPercent 102 // of the heap as maximum. 103 // 104 // If only -XX:MaxNewSize is set we should use the specified value as the 105 // maximum size for young gen. Still using G1DefaultMinNewGenPercent 106 // of the heap as minimum. 107 // 108 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values. 109 // No updates when the heap size changes. There is a special case when 110 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a 111 // different heuristic for calculating the collection set when we do mixed 112 // collection. 113 // 114 // If only -XX:NewRatio is set we should use the specified ratio of the heap 115 // as both min and max. This will be interpreted as "fixed" just like the 116 // NewSize==MaxNewSize case above. But we will update the min and max 117 // everytime the heap size changes. 118 // 119 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is 120 // combined with either NewSize or MaxNewSize. (A warning message is printed.) 121 class G1YoungGenSizer : public CHeapObj { 122 private: 123 enum SizerKind { 124 SizerDefaults, 125 SizerNewSizeOnly, 126 SizerMaxNewSizeOnly, 127 SizerMaxAndNewSize, 128 SizerNewRatio 129 }; 130 SizerKind _sizer_kind; 131 uint _min_desired_young_length; 132 uint _max_desired_young_length; 133 bool _adaptive_size; 134 uint calculate_default_min_length(uint new_number_of_heap_regions); 135 uint calculate_default_max_length(uint new_number_of_heap_regions); 136 137 public: 138 G1YoungGenSizer(); 139 void heap_size_changed(uint new_number_of_heap_regions); 140 uint min_desired_young_length() { 141 return _min_desired_young_length; 142 } 143 uint max_desired_young_length() { 144 return _max_desired_young_length; 145 } 146 bool adaptive_young_list_length() { 147 return _adaptive_size; 148 } 149 }; 150 151 class G1CollectorPolicy: public CollectorPolicy { 152 private: 153 // either equal to the number of parallel threads, if ParallelGCThreads 154 // has been set, or 1 otherwise 155 int _parallel_gc_threads; 156 157 // The number of GC threads currently active. 158 uintx _no_of_gc_threads; 159 160 enum SomePrivateConstants { 161 NumPrevPausesForHeuristics = 10 162 }; 163 164 G1MMUTracker* _mmu_tracker; 165 166 void initialize_flags(); 167 168 void initialize_all() { 169 initialize_flags(); 170 initialize_size_info(); 171 initialize_perm_generation(PermGen::MarkSweepCompact); 172 } 173 174 CollectionSetChooser* _collectionSetChooser; 175 176 double _cur_collection_start_sec; 177 size_t _cur_collection_pause_used_at_start_bytes; 178 uint _cur_collection_pause_used_regions_at_start; 179 double _cur_collection_par_time_ms; 180 181 double _cur_collection_code_root_fixup_time_ms; 182 183 double _cur_clear_ct_time_ms; 184 double _cur_ref_proc_time_ms; 185 double _cur_ref_enq_time_ms; 186 187 #ifndef PRODUCT 188 // Card Table Count Cache stats 189 double _min_clear_cc_time_ms; // min 190 double _max_clear_cc_time_ms; // max 191 double _cur_clear_cc_time_ms; // clearing time during current pause 192 double _cum_clear_cc_time_ms; // cummulative clearing time 193 jlong _num_cc_clears; // number of times the card count cache has been cleared 194 #endif 195 196 // These exclude marking times. 197 TruncatedSeq* _recent_gc_times_ms; 198 199 TruncatedSeq* _concurrent_mark_remark_times_ms; 200 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 201 202 Summary* _summary; 203 204 NumberSeq* _all_pause_times_ms; 205 NumberSeq* _all_full_gc_times_ms; 206 double _stop_world_start; 207 NumberSeq* _all_stop_world_times_ms; 208 NumberSeq* _all_yield_times_ms; 209 210 int _aux_num; 211 NumberSeq* _all_aux_times_ms; 212 double* _cur_aux_start_times_ms; 213 double* _cur_aux_times_ms; 214 bool* _cur_aux_times_set; 215 216 double* _par_last_gc_worker_start_times_ms; 217 double* _par_last_ext_root_scan_times_ms; 218 double* _par_last_satb_filtering_times_ms; 219 double* _par_last_update_rs_times_ms; 220 double* _par_last_update_rs_processed_buffers; 221 double* _par_last_scan_rs_times_ms; 222 double* _par_last_obj_copy_times_ms; 223 double* _par_last_termination_times_ms; 224 double* _par_last_termination_attempts; 225 double* _par_last_gc_worker_end_times_ms; 226 double* _par_last_gc_worker_times_ms; 227 228 // Each workers 'other' time i.e. the elapsed time of the parallel 229 // code executed by a worker minus the sum of the individual sub-phase 230 // times for that worker thread. 231 double* _par_last_gc_worker_other_times_ms; 232 233 // indicates whether we are in young or mixed GC mode 234 bool _gcs_are_young; 235 236 uint _young_list_target_length; 237 uint _young_list_fixed_length; 238 size_t _prev_eden_capacity; // used for logging 239 240 // The max number of regions we can extend the eden by while the GC 241 // locker is active. This should be >= _young_list_target_length; 242 uint _young_list_max_length; 243 244 bool _last_gc_was_young; 245 246 unsigned _young_pause_num; 247 unsigned _mixed_pause_num; 248 249 bool _during_marking; 250 bool _in_marking_window; 251 bool _in_marking_window_im; 252 253 SurvRateGroup* _short_lived_surv_rate_group; 254 SurvRateGroup* _survivor_surv_rate_group; 255 // add here any more surv rate groups 256 257 double _gc_overhead_perc; 258 259 double _reserve_factor; 260 uint _reserve_regions; 261 262 bool during_marking() { 263 return _during_marking; 264 } 265 266 private: 267 enum PredictionConstants { 268 TruncatedSeqLength = 10 269 }; 270 271 TruncatedSeq* _alloc_rate_ms_seq; 272 double _prev_collection_pause_end_ms; 273 274 TruncatedSeq* _pending_card_diff_seq; 275 TruncatedSeq* _rs_length_diff_seq; 276 TruncatedSeq* _cost_per_card_ms_seq; 277 TruncatedSeq* _young_cards_per_entry_ratio_seq; 278 TruncatedSeq* _mixed_cards_per_entry_ratio_seq; 279 TruncatedSeq* _cost_per_entry_ms_seq; 280 TruncatedSeq* _mixed_cost_per_entry_ms_seq; 281 TruncatedSeq* _cost_per_byte_ms_seq; 282 TruncatedSeq* _constant_other_time_ms_seq; 283 TruncatedSeq* _young_other_cost_per_region_ms_seq; 284 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 285 286 TruncatedSeq* _pending_cards_seq; 287 TruncatedSeq* _rs_lengths_seq; 288 289 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 290 291 G1YoungGenSizer* _young_gen_sizer; 292 293 uint _eden_cset_region_length; 294 uint _survivor_cset_region_length; 295 uint _old_cset_region_length; 296 297 void init_cset_region_lengths(uint eden_cset_region_length, 298 uint survivor_cset_region_length); 299 300 uint eden_cset_region_length() { return _eden_cset_region_length; } 301 uint survivor_cset_region_length() { return _survivor_cset_region_length; } 302 uint old_cset_region_length() { return _old_cset_region_length; } 303 304 uint _free_regions_at_end_of_collection; 305 306 size_t _recorded_rs_lengths; 307 size_t _max_rs_lengths; 308 309 double _recorded_young_free_cset_time_ms; 310 double _recorded_non_young_free_cset_time_ms; 311 312 double _sigma; 313 314 size_t _rs_lengths_prediction; 315 316 double sigma() { return _sigma; } 317 318 // A function that prevents us putting too much stock in small sample 319 // sets. Returns a number between 2.0 and 1.0, depending on the number 320 // of samples. 5 or more samples yields one; fewer scales linearly from 321 // 2.0 at 1 sample to 1.0 at 5. 322 double confidence_factor(int samples) { 323 if (samples > 4) return 1.0; 324 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 325 } 326 327 double get_new_neg_prediction(TruncatedSeq* seq) { 328 return seq->davg() - sigma() * seq->dsd(); 329 } 330 331 #ifndef PRODUCT 332 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 333 #endif // PRODUCT 334 335 void adjust_concurrent_refinement(double update_rs_time, 336 double update_rs_processed_buffers, 337 double goal_ms); 338 339 uintx no_of_gc_threads() { return _no_of_gc_threads; } 340 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; } 341 342 double _pause_time_target_ms; 343 double _recorded_young_cset_choice_time_ms; 344 double _recorded_non_young_cset_choice_time_ms; 345 size_t _pending_cards; 346 size_t _max_pending_cards; 347 348 public: 349 // Accessors 350 351 void set_region_eden(HeapRegion* hr, int young_index_in_cset) { 352 hr->set_young(); 353 hr->install_surv_rate_group(_short_lived_surv_rate_group); 354 hr->set_young_index_in_cset(young_index_in_cset); 355 } 356 357 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) { 358 assert(hr->is_young() && hr->is_survivor(), "pre-condition"); 359 hr->install_surv_rate_group(_survivor_surv_rate_group); 360 hr->set_young_index_in_cset(young_index_in_cset); 361 } 362 363 #ifndef PRODUCT 364 bool verify_young_ages(); 365 #endif // PRODUCT 366 367 double get_new_prediction(TruncatedSeq* seq) { 368 return MAX2(seq->davg() + sigma() * seq->dsd(), 369 seq->davg() * confidence_factor(seq->num())); 370 } 371 372 void record_max_rs_lengths(size_t rs_lengths) { 373 _max_rs_lengths = rs_lengths; 374 } 375 376 size_t predict_pending_card_diff() { 377 double prediction = get_new_neg_prediction(_pending_card_diff_seq); 378 if (prediction < 0.00001) { 379 return 0; 380 } else { 381 return (size_t) prediction; 382 } 383 } 384 385 size_t predict_pending_cards() { 386 size_t max_pending_card_num = _g1->max_pending_card_num(); 387 size_t diff = predict_pending_card_diff(); 388 size_t prediction; 389 if (diff > max_pending_card_num) { 390 prediction = max_pending_card_num; 391 } else { 392 prediction = max_pending_card_num - diff; 393 } 394 395 return prediction; 396 } 397 398 size_t predict_rs_length_diff() { 399 return (size_t) get_new_prediction(_rs_length_diff_seq); 400 } 401 402 double predict_alloc_rate_ms() { 403 return get_new_prediction(_alloc_rate_ms_seq); 404 } 405 406 double predict_cost_per_card_ms() { 407 return get_new_prediction(_cost_per_card_ms_seq); 408 } 409 410 double predict_rs_update_time_ms(size_t pending_cards) { 411 return (double) pending_cards * predict_cost_per_card_ms(); 412 } 413 414 double predict_young_cards_per_entry_ratio() { 415 return get_new_prediction(_young_cards_per_entry_ratio_seq); 416 } 417 418 double predict_mixed_cards_per_entry_ratio() { 419 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 420 return predict_young_cards_per_entry_ratio(); 421 } else { 422 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 423 } 424 } 425 426 size_t predict_young_card_num(size_t rs_length) { 427 return (size_t) ((double) rs_length * 428 predict_young_cards_per_entry_ratio()); 429 } 430 431 size_t predict_non_young_card_num(size_t rs_length) { 432 return (size_t) ((double) rs_length * 433 predict_mixed_cards_per_entry_ratio()); 434 } 435 436 double predict_rs_scan_time_ms(size_t card_num) { 437 if (gcs_are_young()) { 438 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 439 } else { 440 return predict_mixed_rs_scan_time_ms(card_num); 441 } 442 } 443 444 double predict_mixed_rs_scan_time_ms(size_t card_num) { 445 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 446 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 447 } else { 448 return (double) (card_num * 449 get_new_prediction(_mixed_cost_per_entry_ms_seq)); 450 } 451 } 452 453 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 454 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 455 return (1.1 * (double) bytes_to_copy) * 456 get_new_prediction(_cost_per_byte_ms_seq); 457 } else { 458 return (double) bytes_to_copy * 459 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 460 } 461 } 462 463 double predict_object_copy_time_ms(size_t bytes_to_copy) { 464 if (_in_marking_window && !_in_marking_window_im) { 465 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 466 } else { 467 return (double) bytes_to_copy * 468 get_new_prediction(_cost_per_byte_ms_seq); 469 } 470 } 471 472 double predict_constant_other_time_ms() { 473 return get_new_prediction(_constant_other_time_ms_seq); 474 } 475 476 double predict_young_other_time_ms(size_t young_num) { 477 return (double) young_num * 478 get_new_prediction(_young_other_cost_per_region_ms_seq); 479 } 480 481 double predict_non_young_other_time_ms(size_t non_young_num) { 482 return (double) non_young_num * 483 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 484 } 485 486 double predict_base_elapsed_time_ms(size_t pending_cards); 487 double predict_base_elapsed_time_ms(size_t pending_cards, 488 size_t scanned_cards); 489 size_t predict_bytes_to_copy(HeapRegion* hr); 490 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); 491 492 void set_recorded_rs_lengths(size_t rs_lengths); 493 494 uint cset_region_length() { return young_cset_region_length() + 495 old_cset_region_length(); } 496 uint young_cset_region_length() { return eden_cset_region_length() + 497 survivor_cset_region_length(); } 498 499 void record_young_free_cset_time_ms(double time_ms) { 500 _recorded_young_free_cset_time_ms = time_ms; 501 } 502 503 void record_non_young_free_cset_time_ms(double time_ms) { 504 _recorded_non_young_free_cset_time_ms = time_ms; 505 } 506 507 double predict_survivor_regions_evac_time(); 508 509 void cset_regions_freed() { 510 bool propagate = _last_gc_was_young && !_in_marking_window; 511 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 512 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 513 // also call it on any more surv rate groups 514 } 515 516 G1MMUTracker* mmu_tracker() { 517 return _mmu_tracker; 518 } 519 520 double max_pause_time_ms() { 521 return _mmu_tracker->max_gc_time() * 1000.0; 522 } 523 524 double predict_remark_time_ms() { 525 return get_new_prediction(_concurrent_mark_remark_times_ms); 526 } 527 528 double predict_cleanup_time_ms() { 529 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 530 } 531 532 // Returns an estimate of the survival rate of the region at yg-age 533 // "yg_age". 534 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 535 TruncatedSeq* seq = surv_rate_group->get_seq(age); 536 if (seq->num() == 0) 537 gclog_or_tty->print("BARF! age is %d", age); 538 guarantee( seq->num() > 0, "invariant" ); 539 double pred = get_new_prediction(seq); 540 if (pred > 1.0) 541 pred = 1.0; 542 return pred; 543 } 544 545 double predict_yg_surv_rate(int age) { 546 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 547 } 548 549 double accum_yg_surv_rate_pred(int age) { 550 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 551 } 552 553 private: 554 void print_stats(int level, const char* str, double value); 555 void print_stats(int level, const char* str, double value, int workers); 556 void print_stats(int level, const char* str, int value); 557 558 void print_par_stats(int level, const char* str, double* data, bool showDecimals = true); 559 560 void check_other_times(int level, 561 NumberSeq* other_times_ms, 562 NumberSeq* calc_other_times_ms) const; 563 564 void print_summary (PauseSummary* stats) const; 565 566 void print_summary (int level, const char* str, NumberSeq* seq) const; 567 void print_summary_sd (int level, const char* str, NumberSeq* seq) const; 568 569 double avg_value (double* data); 570 double max_value (double* data); 571 double sum_of_values (double* data); 572 double max_sum (double* data1, double* data2); 573 574 double _last_pause_time_ms; 575 576 size_t _bytes_in_collection_set_before_gc; 577 size_t _bytes_copied_during_gc; 578 579 // Used to count used bytes in CS. 580 friend class CountCSClosure; 581 582 // Statistics kept per GC stoppage, pause or full. 583 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 584 585 // Add a new GC of the given duration and end time to the record. 586 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 587 588 // The head of the list (via "next_in_collection_set()") representing the 589 // current collection set. Set from the incrementally built collection 590 // set at the start of the pause. 591 HeapRegion* _collection_set; 592 593 // The number of bytes in the collection set before the pause. Set from 594 // the incrementally built collection set at the start of an evacuation 595 // pause. 596 size_t _collection_set_bytes_used_before; 597 598 // The associated information that is maintained while the incremental 599 // collection set is being built with young regions. Used to populate 600 // the recorded info for the evacuation pause. 601 602 enum CSetBuildType { 603 Active, // We are actively building the collection set 604 Inactive // We are not actively building the collection set 605 }; 606 607 CSetBuildType _inc_cset_build_state; 608 609 // The head of the incrementally built collection set. 610 HeapRegion* _inc_cset_head; 611 612 // The tail of the incrementally built collection set. 613 HeapRegion* _inc_cset_tail; 614 615 // The number of bytes in the incrementally built collection set. 616 // Used to set _collection_set_bytes_used_before at the start of 617 // an evacuation pause. 618 size_t _inc_cset_bytes_used_before; 619 620 // Used to record the highest end of heap region in collection set 621 HeapWord* _inc_cset_max_finger; 622 623 // The RSet lengths recorded for regions in the CSet. It is updated 624 // by the thread that adds a new region to the CSet. We assume that 625 // only one thread can be allocating a new CSet region (currently, 626 // it does so after taking the Heap_lock) hence no need to 627 // synchronize updates to this field. 628 size_t _inc_cset_recorded_rs_lengths; 629 630 // A concurrent refinement thread periodcially samples the young 631 // region RSets and needs to update _inc_cset_recorded_rs_lengths as 632 // the RSets grow. Instead of having to syncronize updates to that 633 // field we accumulate them in this field and add it to 634 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC. 635 ssize_t _inc_cset_recorded_rs_lengths_diffs; 636 637 // The predicted elapsed time it will take to collect the regions in 638 // the CSet. This is updated by the thread that adds a new region to 639 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about 640 // MT-safety assumptions. 641 double _inc_cset_predicted_elapsed_time_ms; 642 643 // See the comment for _inc_cset_recorded_rs_lengths_diffs. 644 double _inc_cset_predicted_elapsed_time_ms_diffs; 645 646 // Stash a pointer to the g1 heap. 647 G1CollectedHeap* _g1; 648 649 // The ratio of gc time to elapsed time, computed over recent pauses. 650 double _recent_avg_pause_time_ratio; 651 652 double recent_avg_pause_time_ratio() { 653 return _recent_avg_pause_time_ratio; 654 } 655 656 // At the end of a pause we check the heap occupancy and we decide 657 // whether we will start a marking cycle during the next pause. If 658 // we decide that we want to do that, we will set this parameter to 659 // true. So, this parameter will stay true between the end of a 660 // pause and the beginning of a subsequent pause (not necessarily 661 // the next one, see the comments on the next field) when we decide 662 // that we will indeed start a marking cycle and do the initial-mark 663 // work. 664 volatile bool _initiate_conc_mark_if_possible; 665 666 // If initiate_conc_mark_if_possible() is set at the beginning of a 667 // pause, it is a suggestion that the pause should start a marking 668 // cycle by doing the initial-mark work. However, it is possible 669 // that the concurrent marking thread is still finishing up the 670 // previous marking cycle (e.g., clearing the next marking 671 // bitmap). If that is the case we cannot start a new cycle and 672 // we'll have to wait for the concurrent marking thread to finish 673 // what it is doing. In this case we will postpone the marking cycle 674 // initiation decision for the next pause. When we eventually decide 675 // to start a cycle, we will set _during_initial_mark_pause which 676 // will stay true until the end of the initial-mark pause and it's 677 // the condition that indicates that a pause is doing the 678 // initial-mark work. 679 volatile bool _during_initial_mark_pause; 680 681 bool _last_young_gc; 682 683 // This set of variables tracks the collector efficiency, in order to 684 // determine whether we should initiate a new marking. 685 double _cur_mark_stop_world_time_ms; 686 double _mark_remark_start_sec; 687 double _mark_cleanup_start_sec; 688 double _root_region_scan_wait_time_ms; 689 690 // Update the young list target length either by setting it to the 691 // desired fixed value or by calculating it using G1's pause 692 // prediction model. If no rs_lengths parameter is passed, predict 693 // the RS lengths using the prediction model, otherwise use the 694 // given rs_lengths as the prediction. 695 void update_young_list_target_length(size_t rs_lengths = (size_t) -1); 696 697 // Calculate and return the minimum desired young list target 698 // length. This is the minimum desired young list length according 699 // to the user's inputs. 700 uint calculate_young_list_desired_min_length(uint base_min_length); 701 702 // Calculate and return the maximum desired young list target 703 // length. This is the maximum desired young list length according 704 // to the user's inputs. 705 uint calculate_young_list_desired_max_length(); 706 707 // Calculate and return the maximum young list target length that 708 // can fit into the pause time goal. The parameters are: rs_lengths 709 // represent the prediction of how large the young RSet lengths will 710 // be, base_min_length is the alreay existing number of regions in 711 // the young list, min_length and max_length are the desired min and 712 // max young list length according to the user's inputs. 713 uint calculate_young_list_target_length(size_t rs_lengths, 714 uint base_min_length, 715 uint desired_min_length, 716 uint desired_max_length); 717 718 // Check whether a given young length (young_length) fits into the 719 // given target pause time and whether the prediction for the amount 720 // of objects to be copied for the given length will fit into the 721 // given free space (expressed by base_free_regions). It is used by 722 // calculate_young_list_target_length(). 723 bool predict_will_fit(uint young_length, double base_time_ms, 724 uint base_free_regions, double target_pause_time_ms); 725 726 // Count the number of bytes used in the CS. 727 void count_CS_bytes_used(); 728 729 public: 730 731 G1CollectorPolicy(); 732 733 virtual G1CollectorPolicy* as_g1_policy() { return this; } 734 735 virtual CollectorPolicy::Name kind() { 736 return CollectorPolicy::G1CollectorPolicyKind; 737 } 738 739 // Check the current value of the young list RSet lengths and 740 // compare it against the last prediction. If the current value is 741 // higher, recalculate the young list target length prediction. 742 void revise_young_list_target_length_if_necessary(); 743 744 size_t bytes_in_collection_set() { 745 return _bytes_in_collection_set_before_gc; 746 } 747 748 unsigned calc_gc_alloc_time_stamp() { 749 return _all_pause_times_ms->num() + 1; 750 } 751 752 // This should be called after the heap is resized. 753 void record_new_heap_size(uint new_number_of_regions); 754 755 void init(); 756 757 // Create jstat counters for the policy. 758 virtual void initialize_gc_policy_counters(); 759 760 virtual HeapWord* mem_allocate_work(size_t size, 761 bool is_tlab, 762 bool* gc_overhead_limit_was_exceeded); 763 764 // This method controls how a collector handles one or more 765 // of its generations being fully allocated. 766 virtual HeapWord* satisfy_failed_allocation(size_t size, 767 bool is_tlab); 768 769 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 770 771 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; } 772 773 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 774 775 // Update the heuristic info to record a collection pause of the given 776 // start time, where the given number of bytes were used at the start. 777 // This may involve changing the desired size of a collection set. 778 779 void record_stop_world_start(); 780 781 void record_collection_pause_start(double start_time_sec, size_t start_used); 782 783 // Must currently be called while the world is stopped. 784 void record_concurrent_mark_init_end(double 785 mark_init_elapsed_time_ms); 786 787 void record_root_region_scan_wait_time(double time_ms) { 788 _root_region_scan_wait_time_ms = time_ms; 789 } 790 791 void record_concurrent_mark_remark_start(); 792 void record_concurrent_mark_remark_end(); 793 794 void record_concurrent_mark_cleanup_start(); 795 void record_concurrent_mark_cleanup_end(int no_of_gc_threads); 796 void record_concurrent_mark_cleanup_completed(); 797 798 void record_concurrent_pause(); 799 void record_concurrent_pause_end(); 800 801 void record_collection_pause_end(int no_of_gc_threads); 802 void print_heap_transition(); 803 804 // Record the fact that a full collection occurred. 805 void record_full_collection_start(); 806 void record_full_collection_end(); 807 808 void record_gc_worker_start_time(int worker_i, double ms) { 809 _par_last_gc_worker_start_times_ms[worker_i] = ms; 810 } 811 812 void record_ext_root_scan_time(int worker_i, double ms) { 813 _par_last_ext_root_scan_times_ms[worker_i] = ms; 814 } 815 816 void record_satb_filtering_time(int worker_i, double ms) { 817 _par_last_satb_filtering_times_ms[worker_i] = ms; 818 } 819 820 void record_update_rs_time(int thread, double ms) { 821 _par_last_update_rs_times_ms[thread] = ms; 822 } 823 824 void record_update_rs_processed_buffers (int thread, 825 double processed_buffers) { 826 _par_last_update_rs_processed_buffers[thread] = processed_buffers; 827 } 828 829 void record_scan_rs_time(int thread, double ms) { 830 _par_last_scan_rs_times_ms[thread] = ms; 831 } 832 833 void reset_obj_copy_time(int thread) { 834 _par_last_obj_copy_times_ms[thread] = 0.0; 835 } 836 837 void reset_obj_copy_time() { 838 reset_obj_copy_time(0); 839 } 840 841 void record_obj_copy_time(int thread, double ms) { 842 _par_last_obj_copy_times_ms[thread] += ms; 843 } 844 845 void record_termination(int thread, double ms, size_t attempts) { 846 _par_last_termination_times_ms[thread] = ms; 847 _par_last_termination_attempts[thread] = (double) attempts; 848 } 849 850 void record_gc_worker_end_time(int worker_i, double ms) { 851 _par_last_gc_worker_end_times_ms[worker_i] = ms; 852 } 853 854 void record_pause_time_ms(double ms) { 855 _last_pause_time_ms = ms; 856 } 857 858 void record_clear_ct_time(double ms) { 859 _cur_clear_ct_time_ms = ms; 860 } 861 862 void record_par_time(double ms) { 863 _cur_collection_par_time_ms = ms; 864 } 865 866 void record_code_root_fixup_time(double ms) { 867 _cur_collection_code_root_fixup_time_ms = ms; 868 } 869 870 void record_aux_start_time(int i) { 871 guarantee(i < _aux_num, "should be within range"); 872 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0; 873 } 874 875 void record_aux_end_time(int i) { 876 guarantee(i < _aux_num, "should be within range"); 877 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i]; 878 _cur_aux_times_set[i] = true; 879 _cur_aux_times_ms[i] += ms; 880 } 881 882 void record_ref_proc_time(double ms) { 883 _cur_ref_proc_time_ms = ms; 884 } 885 886 void record_ref_enq_time(double ms) { 887 _cur_ref_enq_time_ms = ms; 888 } 889 890 #ifndef PRODUCT 891 void record_cc_clear_time(double ms) { 892 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms) 893 _min_clear_cc_time_ms = ms; 894 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms) 895 _max_clear_cc_time_ms = ms; 896 _cur_clear_cc_time_ms = ms; 897 _cum_clear_cc_time_ms += ms; 898 _num_cc_clears++; 899 } 900 #endif 901 902 // Record how much space we copied during a GC. This is typically 903 // called when a GC alloc region is being retired. 904 void record_bytes_copied_during_gc(size_t bytes) { 905 _bytes_copied_during_gc += bytes; 906 } 907 908 // The amount of space we copied during a GC. 909 size_t bytes_copied_during_gc() { 910 return _bytes_copied_during_gc; 911 } 912 913 // Determine whether there are candidate regions so that the 914 // next GC should be mixed. The two action strings are used 915 // in the ergo output when the method returns true or false. 916 bool next_gc_should_be_mixed(const char* true_action_str, 917 const char* false_action_str); 918 919 // Choose a new collection set. Marks the chosen regions as being 920 // "in_collection_set", and links them together. The head and number of 921 // the collection set are available via access methods. 922 void finalize_cset(double target_pause_time_ms); 923 924 // The head of the list (via "next_in_collection_set()") representing the 925 // current collection set. 926 HeapRegion* collection_set() { return _collection_set; } 927 928 void clear_collection_set() { _collection_set = NULL; } 929 930 // Add old region "hr" to the CSet. 931 void add_old_region_to_cset(HeapRegion* hr); 932 933 // Incremental CSet Support 934 935 // The head of the incrementally built collection set. 936 HeapRegion* inc_cset_head() { return _inc_cset_head; } 937 938 // The tail of the incrementally built collection set. 939 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 940 941 // Initialize incremental collection set info. 942 void start_incremental_cset_building(); 943 944 // Perform any final calculations on the incremental CSet fields 945 // before we can use them. 946 void finalize_incremental_cset_building(); 947 948 void clear_incremental_cset() { 949 _inc_cset_head = NULL; 950 _inc_cset_tail = NULL; 951 } 952 953 // Stop adding regions to the incremental collection set 954 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 955 956 // Add information about hr to the aggregated information for the 957 // incrementally built collection set. 958 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 959 960 // Update information about hr in the aggregated information for 961 // the incrementally built collection set. 962 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 963 964 private: 965 // Update the incremental cset information when adding a region 966 // (should not be called directly). 967 void add_region_to_incremental_cset_common(HeapRegion* hr); 968 969 public: 970 // Add hr to the LHS of the incremental collection set. 971 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 972 973 // Add hr to the RHS of the incremental collection set. 974 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 975 976 #ifndef PRODUCT 977 void print_collection_set(HeapRegion* list_head, outputStream* st); 978 #endif // !PRODUCT 979 980 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 981 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 982 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 983 984 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 985 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 986 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 987 988 // This sets the initiate_conc_mark_if_possible() flag to start a 989 // new cycle, as long as we are not already in one. It's best if it 990 // is called during a safepoint when the test whether a cycle is in 991 // progress or not is stable. 992 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause); 993 994 // This is called at the very beginning of an evacuation pause (it 995 // has to be the first thing that the pause does). If 996 // initiate_conc_mark_if_possible() is true, and the concurrent 997 // marking thread has completed its work during the previous cycle, 998 // it will set during_initial_mark_pause() to so that the pause does 999 // the initial-mark work and start a marking cycle. 1000 void decide_on_conc_mark_initiation(); 1001 1002 // If an expansion would be appropriate, because recent GC overhead had 1003 // exceeded the desired limit, return an amount to expand by. 1004 size_t expansion_amount(); 1005 1006 // Print tracing information. 1007 void print_tracing_info() const; 1008 1009 // Print stats on young survival ratio 1010 void print_yg_surv_rate_info() const; 1011 1012 void finished_recalculating_age_indexes(bool is_survivors) { 1013 if (is_survivors) { 1014 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 1015 } else { 1016 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 1017 } 1018 // do that for any other surv rate groups 1019 } 1020 1021 bool is_young_list_full() { 1022 uint young_list_length = _g1->young_list()->length(); 1023 uint young_list_target_length = _young_list_target_length; 1024 return young_list_length >= young_list_target_length; 1025 } 1026 1027 bool can_expand_young_list() { 1028 uint young_list_length = _g1->young_list()->length(); 1029 uint young_list_max_length = _young_list_max_length; 1030 return young_list_length < young_list_max_length; 1031 } 1032 1033 uint young_list_max_length() { 1034 return _young_list_max_length; 1035 } 1036 1037 bool gcs_are_young() { 1038 return _gcs_are_young; 1039 } 1040 void set_gcs_are_young(bool gcs_are_young) { 1041 _gcs_are_young = gcs_are_young; 1042 } 1043 1044 bool adaptive_young_list_length() { 1045 return _young_gen_sizer->adaptive_young_list_length(); 1046 } 1047 1048 private: 1049 // 1050 // Survivor regions policy. 1051 // 1052 1053 // Current tenuring threshold, set to 0 if the collector reaches the 1054 // maximum amount of suvivors regions. 1055 int _tenuring_threshold; 1056 1057 // The limit on the number of regions allocated for survivors. 1058 uint _max_survivor_regions; 1059 1060 // For reporting purposes. 1061 size_t _eden_bytes_before_gc; 1062 size_t _survivor_bytes_before_gc; 1063 size_t _capacity_before_gc; 1064 1065 // The amount of survor regions after a collection. 1066 uint _recorded_survivor_regions; 1067 // List of survivor regions. 1068 HeapRegion* _recorded_survivor_head; 1069 HeapRegion* _recorded_survivor_tail; 1070 1071 ageTable _survivors_age_table; 1072 1073 public: 1074 1075 inline GCAllocPurpose 1076 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) { 1077 if (age < _tenuring_threshold && src_region->is_young()) { 1078 return GCAllocForSurvived; 1079 } else { 1080 return GCAllocForTenured; 1081 } 1082 } 1083 1084 inline bool track_object_age(GCAllocPurpose purpose) { 1085 return purpose == GCAllocForSurvived; 1086 } 1087 1088 static const uint REGIONS_UNLIMITED = (uint) -1; 1089 1090 uint max_regions(int purpose); 1091 1092 // The limit on regions for a particular purpose is reached. 1093 void note_alloc_region_limit_reached(int purpose) { 1094 if (purpose == GCAllocForSurvived) { 1095 _tenuring_threshold = 0; 1096 } 1097 } 1098 1099 void note_start_adding_survivor_regions() { 1100 _survivor_surv_rate_group->start_adding_regions(); 1101 } 1102 1103 void note_stop_adding_survivor_regions() { 1104 _survivor_surv_rate_group->stop_adding_regions(); 1105 } 1106 1107 void record_survivor_regions(uint regions, 1108 HeapRegion* head, 1109 HeapRegion* tail) { 1110 _recorded_survivor_regions = regions; 1111 _recorded_survivor_head = head; 1112 _recorded_survivor_tail = tail; 1113 } 1114 1115 uint recorded_survivor_regions() { 1116 return _recorded_survivor_regions; 1117 } 1118 1119 void record_thread_age_table(ageTable* age_table) { 1120 _survivors_age_table.merge_par(age_table); 1121 } 1122 1123 void update_max_gc_locker_expansion(); 1124 1125 // Calculates survivor space parameters. 1126 void update_survivors_policy(); 1127 1128 }; 1129 1130 // This should move to some place more general... 1131 1132 // If we have "n" measurements, and we've kept track of their "sum" and the 1133 // "sum_of_squares" of the measurements, this returns the variance of the 1134 // sequence. 1135 inline double variance(int n, double sum_of_squares, double sum) { 1136 double n_d = (double)n; 1137 double avg = sum/n_d; 1138 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 1139 } 1140 1141 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP