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 // TraceGen0Time 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 Gen1) while TraceGen1Time collects data about full GCs. 44 class TraceGen0TimeData : 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 TraceGen0TimeData() : _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 TraceGen1TimeData : 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 // everytime 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 public: 140 G1YoungGenSizer(); 141 void heap_size_changed(uint new_number_of_heap_regions); 142 uint min_desired_young_length() { 143 return _min_desired_young_length; 144 } 145 uint max_desired_young_length() { 146 return _max_desired_young_length; 147 } 148 bool adaptive_young_list_length() { 149 return _adaptive_size; 150 } 151 }; 152 153 class G1CollectorPolicy: public CollectorPolicy { 154 private: 155 // either equal to the number of parallel threads, if ParallelGCThreads 156 // has been set, or 1 otherwise 157 int _parallel_gc_threads; 158 159 // The number of GC threads currently active. 160 uintx _no_of_gc_threads; 161 162 enum SomePrivateConstants { 163 NumPrevPausesForHeuristics = 10 164 }; 165 166 G1MMUTracker* _mmu_tracker; 167 168 void initialize_flags(); 169 170 void initialize_all() { 171 initialize_flags(); 172 initialize_size_info(); 173 } 174 175 CollectionSetChooser* _collectionSetChooser; 176 177 double _full_collection_start_sec; 178 uint _cur_collection_pause_used_regions_at_start; 179 180 // These exclude marking times. 181 TruncatedSeq* _recent_gc_times_ms; 182 183 TruncatedSeq* _concurrent_mark_remark_times_ms; 184 TruncatedSeq* _concurrent_mark_cleanup_times_ms; 185 186 TraceGen0TimeData _trace_gen0_time_data; 187 TraceGen1TimeData _trace_gen1_time_data; 188 189 double _stop_world_start; 190 191 // indicates whether we are in young or mixed GC mode 192 bool _gcs_are_young; 193 194 uint _young_list_target_length; 195 uint _young_list_fixed_length; 196 197 // The max number of regions we can extend the eden by while the GC 198 // locker is active. This should be >= _young_list_target_length; 199 uint _young_list_max_length; 200 201 bool _last_gc_was_young; 202 203 bool _during_marking; 204 bool _in_marking_window; 205 bool _in_marking_window_im; 206 207 SurvRateGroup* _short_lived_surv_rate_group; 208 SurvRateGroup* _survivor_surv_rate_group; 209 // add here any more surv rate groups 210 211 double _gc_overhead_perc; 212 213 double _reserve_factor; 214 uint _reserve_regions; 215 216 bool during_marking() { 217 return _during_marking; 218 } 219 220 private: 221 enum PredictionConstants { 222 TruncatedSeqLength = 10 223 }; 224 225 TruncatedSeq* _alloc_rate_ms_seq; 226 double _prev_collection_pause_end_ms; 227 228 TruncatedSeq* _rs_length_diff_seq; 229 TruncatedSeq* _cost_per_card_ms_seq; 230 TruncatedSeq* _young_cards_per_entry_ratio_seq; 231 TruncatedSeq* _mixed_cards_per_entry_ratio_seq; 232 TruncatedSeq* _cost_per_entry_ms_seq; 233 TruncatedSeq* _mixed_cost_per_entry_ms_seq; 234 TruncatedSeq* _cost_per_byte_ms_seq; 235 TruncatedSeq* _constant_other_time_ms_seq; 236 TruncatedSeq* _young_other_cost_per_region_ms_seq; 237 TruncatedSeq* _non_young_other_cost_per_region_ms_seq; 238 239 TruncatedSeq* _pending_cards_seq; 240 TruncatedSeq* _rs_lengths_seq; 241 242 TruncatedSeq* _cost_per_byte_ms_during_cm_seq; 243 244 G1YoungGenSizer* _young_gen_sizer; 245 246 uint _eden_cset_region_length; 247 uint _survivor_cset_region_length; 248 uint _old_cset_region_length; 249 250 void init_cset_region_lengths(uint eden_cset_region_length, 251 uint survivor_cset_region_length); 252 253 uint eden_cset_region_length() { return _eden_cset_region_length; } 254 uint survivor_cset_region_length() { return _survivor_cset_region_length; } 255 uint old_cset_region_length() { return _old_cset_region_length; } 256 257 uint _free_regions_at_end_of_collection; 258 259 size_t _recorded_rs_lengths; 260 size_t _max_rs_lengths; 261 double _sigma; 262 263 size_t _rs_lengths_prediction; 264 265 double sigma() { return _sigma; } 266 267 // A function that prevents us putting too much stock in small sample 268 // sets. Returns a number between 2.0 and 1.0, depending on the number 269 // of samples. 5 or more samples yields one; fewer scales linearly from 270 // 2.0 at 1 sample to 1.0 at 5. 271 double confidence_factor(int samples) { 272 if (samples > 4) return 1.0; 273 else return 1.0 + sigma() * ((double)(5 - samples))/2.0; 274 } 275 276 double get_new_neg_prediction(TruncatedSeq* seq) { 277 return seq->davg() - sigma() * seq->dsd(); 278 } 279 280 #ifndef PRODUCT 281 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group); 282 #endif // PRODUCT 283 284 void adjust_concurrent_refinement(double update_rs_time, 285 double update_rs_processed_buffers, 286 double goal_ms); 287 288 uintx no_of_gc_threads() { return _no_of_gc_threads; } 289 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; } 290 291 double _pause_time_target_ms; 292 293 size_t _pending_cards; 294 295 public: 296 // Accessors 297 298 void set_region_eden(HeapRegion* hr, int young_index_in_cset) { 299 hr->set_young(); 300 hr->install_surv_rate_group(_short_lived_surv_rate_group); 301 hr->set_young_index_in_cset(young_index_in_cset); 302 } 303 304 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) { 305 assert(hr->is_young() && hr->is_survivor(), "pre-condition"); 306 hr->install_surv_rate_group(_survivor_surv_rate_group); 307 hr->set_young_index_in_cset(young_index_in_cset); 308 } 309 310 #ifndef PRODUCT 311 bool verify_young_ages(); 312 #endif // PRODUCT 313 314 double get_new_prediction(TruncatedSeq* seq) { 315 return MAX2(seq->davg() + sigma() * seq->dsd(), 316 seq->davg() * confidence_factor(seq->num())); 317 } 318 319 void record_max_rs_lengths(size_t rs_lengths) { 320 _max_rs_lengths = rs_lengths; 321 } 322 323 size_t predict_rs_length_diff() { 324 return (size_t) get_new_prediction(_rs_length_diff_seq); 325 } 326 327 double predict_alloc_rate_ms() { 328 return get_new_prediction(_alloc_rate_ms_seq); 329 } 330 331 double predict_cost_per_card_ms() { 332 return get_new_prediction(_cost_per_card_ms_seq); 333 } 334 335 double predict_rs_update_time_ms(size_t pending_cards) { 336 return (double) pending_cards * predict_cost_per_card_ms(); 337 } 338 339 double predict_young_cards_per_entry_ratio() { 340 return get_new_prediction(_young_cards_per_entry_ratio_seq); 341 } 342 343 double predict_mixed_cards_per_entry_ratio() { 344 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 345 return predict_young_cards_per_entry_ratio(); 346 } else { 347 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 348 } 349 } 350 351 size_t predict_young_card_num(size_t rs_length) { 352 return (size_t) ((double) rs_length * 353 predict_young_cards_per_entry_ratio()); 354 } 355 356 size_t predict_non_young_card_num(size_t rs_length) { 357 return (size_t) ((double) rs_length * 358 predict_mixed_cards_per_entry_ratio()); 359 } 360 361 double predict_rs_scan_time_ms(size_t card_num) { 362 if (gcs_are_young()) { 363 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 364 } else { 365 return predict_mixed_rs_scan_time_ms(card_num); 366 } 367 } 368 369 double predict_mixed_rs_scan_time_ms(size_t card_num) { 370 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 371 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq); 372 } else { 373 return (double) (card_num * 374 get_new_prediction(_mixed_cost_per_entry_ms_seq)); 375 } 376 } 377 378 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) { 379 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 380 return (1.1 * (double) bytes_to_copy) * 381 get_new_prediction(_cost_per_byte_ms_seq); 382 } else { 383 return (double) bytes_to_copy * 384 get_new_prediction(_cost_per_byte_ms_during_cm_seq); 385 } 386 } 387 388 double predict_object_copy_time_ms(size_t bytes_to_copy) { 389 if (_in_marking_window && !_in_marking_window_im) { 390 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 391 } else { 392 return (double) bytes_to_copy * 393 get_new_prediction(_cost_per_byte_ms_seq); 394 } 395 } 396 397 double predict_constant_other_time_ms() { 398 return get_new_prediction(_constant_other_time_ms_seq); 399 } 400 401 double predict_young_other_time_ms(size_t young_num) { 402 return (double) young_num * 403 get_new_prediction(_young_other_cost_per_region_ms_seq); 404 } 405 406 double predict_non_young_other_time_ms(size_t non_young_num) { 407 return (double) non_young_num * 408 get_new_prediction(_non_young_other_cost_per_region_ms_seq); 409 } 410 411 double predict_base_elapsed_time_ms(size_t pending_cards); 412 double predict_base_elapsed_time_ms(size_t pending_cards, 413 size_t scanned_cards); 414 size_t predict_bytes_to_copy(HeapRegion* hr); 415 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc); 416 417 void set_recorded_rs_lengths(size_t rs_lengths); 418 419 uint cset_region_length() { return young_cset_region_length() + 420 old_cset_region_length(); } 421 uint young_cset_region_length() { return eden_cset_region_length() + 422 survivor_cset_region_length(); } 423 424 double predict_survivor_regions_evac_time(); 425 426 void cset_regions_freed() { 427 bool propagate = _last_gc_was_young && !_in_marking_window; 428 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate); 429 _survivor_surv_rate_group->all_surviving_words_recorded(propagate); 430 // also call it on any more surv rate groups 431 } 432 433 G1MMUTracker* mmu_tracker() { 434 return _mmu_tracker; 435 } 436 437 double max_pause_time_ms() { 438 return _mmu_tracker->max_gc_time() * 1000.0; 439 } 440 441 double predict_remark_time_ms() { 442 return get_new_prediction(_concurrent_mark_remark_times_ms); 443 } 444 445 double predict_cleanup_time_ms() { 446 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 447 } 448 449 // Returns an estimate of the survival rate of the region at yg-age 450 // "yg_age". 451 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) { 452 TruncatedSeq* seq = surv_rate_group->get_seq(age); 453 if (seq->num() == 0) 454 gclog_or_tty->print("BARF! age is %d", age); 455 guarantee( seq->num() > 0, "invariant" ); 456 double pred = get_new_prediction(seq); 457 if (pred > 1.0) 458 pred = 1.0; 459 return pred; 460 } 461 462 double predict_yg_surv_rate(int age) { 463 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 464 } 465 466 double accum_yg_surv_rate_pred(int age) { 467 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 468 } 469 470 private: 471 // Statistics kept per GC stoppage, pause or full. 472 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec; 473 474 // Add a new GC of the given duration and end time to the record. 475 void update_recent_gc_times(double end_time_sec, double elapsed_ms); 476 477 // The head of the list (via "next_in_collection_set()") representing the 478 // current collection set. Set from the incrementally built collection 479 // set at the start of the pause. 480 HeapRegion* _collection_set; 481 482 // The number of bytes in the collection set before the pause. Set from 483 // the incrementally built collection set at the start of an evacuation 484 // pause, and incremented in finalize_cset() when adding old regions 485 // (if any) to the collection set. 486 size_t _collection_set_bytes_used_before; 487 488 // The number of bytes copied during the GC. 489 size_t _bytes_copied_during_gc; 490 491 // The associated information that is maintained while the incremental 492 // collection set is being built with young regions. Used to populate 493 // the recorded info for the evacuation pause. 494 495 enum CSetBuildType { 496 Active, // We are actively building the collection set 497 Inactive // We are not actively building the collection set 498 }; 499 500 CSetBuildType _inc_cset_build_state; 501 502 // The head of the incrementally built collection set. 503 HeapRegion* _inc_cset_head; 504 505 // The tail of the incrementally built collection set. 506 HeapRegion* _inc_cset_tail; 507 508 // The number of bytes in the incrementally built collection set. 509 // Used to set _collection_set_bytes_used_before at the start of 510 // an evacuation pause. 511 size_t _inc_cset_bytes_used_before; 512 513 // Used to record the highest end of heap region in collection set 514 HeapWord* _inc_cset_max_finger; 515 516 // The RSet lengths recorded for regions in the CSet. It is updated 517 // by the thread that adds a new region to the CSet. We assume that 518 // only one thread can be allocating a new CSet region (currently, 519 // it does so after taking the Heap_lock) hence no need to 520 // synchronize updates to this field. 521 size_t _inc_cset_recorded_rs_lengths; 522 523 // A concurrent refinement thread periodcially samples the young 524 // region RSets and needs to update _inc_cset_recorded_rs_lengths as 525 // the RSets grow. Instead of having to syncronize updates to that 526 // field we accumulate them in this field and add it to 527 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC. 528 ssize_t _inc_cset_recorded_rs_lengths_diffs; 529 530 // The predicted elapsed time it will take to collect the regions in 531 // the CSet. This is updated by the thread that adds a new region to 532 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about 533 // MT-safety assumptions. 534 double _inc_cset_predicted_elapsed_time_ms; 535 536 // See the comment for _inc_cset_recorded_rs_lengths_diffs. 537 double _inc_cset_predicted_elapsed_time_ms_diffs; 538 539 // Stash a pointer to the g1 heap. 540 G1CollectedHeap* _g1; 541 542 G1GCPhaseTimes* _phase_times; 543 544 // The ratio of gc time to elapsed time, computed over recent pauses. 545 double _recent_avg_pause_time_ratio; 546 547 double recent_avg_pause_time_ratio() { 548 return _recent_avg_pause_time_ratio; 549 } 550 551 // At the end of a pause we check the heap occupancy and we decide 552 // whether we will start a marking cycle during the next pause. If 553 // we decide that we want to do that, we will set this parameter to 554 // true. So, this parameter will stay true between the end of a 555 // pause and the beginning of a subsequent pause (not necessarily 556 // the next one, see the comments on the next field) when we decide 557 // that we will indeed start a marking cycle and do the initial-mark 558 // work. 559 volatile bool _initiate_conc_mark_if_possible; 560 561 // If initiate_conc_mark_if_possible() is set at the beginning of a 562 // pause, it is a suggestion that the pause should start a marking 563 // cycle by doing the initial-mark work. However, it is possible 564 // that the concurrent marking thread is still finishing up the 565 // previous marking cycle (e.g., clearing the next marking 566 // bitmap). If that is the case we cannot start a new cycle and 567 // we'll have to wait for the concurrent marking thread to finish 568 // what it is doing. In this case we will postpone the marking cycle 569 // initiation decision for the next pause. When we eventually decide 570 // to start a cycle, we will set _during_initial_mark_pause which 571 // will stay true until the end of the initial-mark pause and it's 572 // the condition that indicates that a pause is doing the 573 // initial-mark work. 574 volatile bool _during_initial_mark_pause; 575 576 bool _last_young_gc; 577 578 // This set of variables tracks the collector efficiency, in order to 579 // determine whether we should initiate a new marking. 580 double _cur_mark_stop_world_time_ms; 581 double _mark_remark_start_sec; 582 double _mark_cleanup_start_sec; 583 584 // Update the young list target length either by setting it to the 585 // desired fixed value or by calculating it using G1's pause 586 // prediction model. If no rs_lengths parameter is passed, predict 587 // the RS lengths using the prediction model, otherwise use the 588 // given rs_lengths as the prediction. 589 void update_young_list_target_length(size_t rs_lengths = (size_t) -1); 590 591 // Calculate and return the minimum desired young list target 592 // length. This is the minimum desired young list length according 593 // to the user's inputs. 594 uint calculate_young_list_desired_min_length(uint base_min_length); 595 596 // Calculate and return the maximum desired young list target 597 // length. This is the maximum desired young list length according 598 // to the user's inputs. 599 uint calculate_young_list_desired_max_length(); 600 601 // Calculate and return the maximum young list target length that 602 // can fit into the pause time goal. The parameters are: rs_lengths 603 // represent the prediction of how large the young RSet lengths will 604 // be, base_min_length is the alreay existing number of regions in 605 // the young list, min_length and max_length are the desired min and 606 // max young list length according to the user's inputs. 607 uint calculate_young_list_target_length(size_t rs_lengths, 608 uint base_min_length, 609 uint desired_min_length, 610 uint desired_max_length); 611 612 // Check whether a given young length (young_length) fits into the 613 // given target pause time and whether the prediction for the amount 614 // of objects to be copied for the given length will fit into the 615 // given free space (expressed by base_free_regions). It is used by 616 // calculate_young_list_target_length(). 617 bool predict_will_fit(uint young_length, double base_time_ms, 618 uint base_free_regions, double target_pause_time_ms); 619 620 // Calculate the minimum number of old regions we'll add to the CSet 621 // during a mixed GC. 622 uint calc_min_old_cset_length(); 623 624 // Calculate the maximum number of old regions we'll add to the CSet 625 // during a mixed GC. 626 uint calc_max_old_cset_length(); 627 628 // Returns the given amount of uncollected reclaimable space 629 // as a percentage of the current heap capacity. 630 double reclaimable_bytes_perc(size_t reclaimable_bytes); 631 632 public: 633 634 G1CollectorPolicy(); 635 636 virtual G1CollectorPolicy* as_g1_policy() { return this; } 637 638 virtual CollectorPolicy::Name kind() { 639 return CollectorPolicy::G1CollectorPolicyKind; 640 } 641 642 G1GCPhaseTimes* phase_times() const { return _phase_times; } 643 644 // Check the current value of the young list RSet lengths and 645 // compare it against the last prediction. If the current value is 646 // higher, recalculate the young list target length prediction. 647 void revise_young_list_target_length_if_necessary(); 648 649 // This should be called after the heap is resized. 650 void record_new_heap_size(uint new_number_of_regions); 651 652 void init(); 653 654 // Create jstat counters for the policy. 655 virtual void initialize_gc_policy_counters(); 656 657 virtual HeapWord* mem_allocate_work(size_t size, 658 bool is_tlab, 659 bool* gc_overhead_limit_was_exceeded); 660 661 // This method controls how a collector handles one or more 662 // of its generations being fully allocated. 663 virtual HeapWord* satisfy_failed_allocation(size_t size, 664 bool is_tlab); 665 666 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; } 667 668 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; } 669 670 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0); 671 672 // Record the start and end of an evacuation pause. 673 void record_collection_pause_start(double start_time_sec); 674 void record_collection_pause_end(double pause_time_ms); 675 676 // Record the start and end of a full collection. 677 void record_full_collection_start(); 678 void record_full_collection_end(); 679 680 // Must currently be called while the world is stopped. 681 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms); 682 683 // Record start and end of remark. 684 void record_concurrent_mark_remark_start(); 685 void record_concurrent_mark_remark_end(); 686 687 // Record start, end, and completion of cleanup. 688 void record_concurrent_mark_cleanup_start(); 689 void record_concurrent_mark_cleanup_end(int no_of_gc_threads); 690 void record_concurrent_mark_cleanup_completed(); 691 692 // Records the information about the heap size for reporting in 693 // print_detailed_heap_transition 694 void record_heap_size_info_at_start(bool full); 695 696 // Print heap sizing transition (with less and more detail). 697 void print_heap_transition(); 698 void print_detailed_heap_transition(bool full = false); 699 700 void record_stop_world_start(); 701 void record_concurrent_pause(); 702 703 // Record how much space we copied during a GC. This is typically 704 // called when a GC alloc region is being retired. 705 void record_bytes_copied_during_gc(size_t bytes) { 706 _bytes_copied_during_gc += bytes; 707 } 708 709 // The amount of space we copied during a GC. 710 size_t bytes_copied_during_gc() { 711 return _bytes_copied_during_gc; 712 } 713 714 // Determine whether there are candidate regions so that the 715 // next GC should be mixed. The two action strings are used 716 // in the ergo output when the method returns true or false. 717 bool next_gc_should_be_mixed(const char* true_action_str, 718 const char* false_action_str); 719 720 // Choose a new collection set. Marks the chosen regions as being 721 // "in_collection_set", and links them together. The head and number of 722 // the collection set are available via access methods. 723 void finalize_cset(double target_pause_time_ms); 724 725 // The head of the list (via "next_in_collection_set()") representing the 726 // current collection set. 727 HeapRegion* collection_set() { return _collection_set; } 728 729 void clear_collection_set() { _collection_set = NULL; } 730 731 // Add old region "hr" to the CSet. 732 void add_old_region_to_cset(HeapRegion* hr); 733 734 // Incremental CSet Support 735 736 // The head of the incrementally built collection set. 737 HeapRegion* inc_cset_head() { return _inc_cset_head; } 738 739 // The tail of the incrementally built collection set. 740 HeapRegion* inc_set_tail() { return _inc_cset_tail; } 741 742 // Initialize incremental collection set info. 743 void start_incremental_cset_building(); 744 745 // Perform any final calculations on the incremental CSet fields 746 // before we can use them. 747 void finalize_incremental_cset_building(); 748 749 void clear_incremental_cset() { 750 _inc_cset_head = NULL; 751 _inc_cset_tail = NULL; 752 } 753 754 // Stop adding regions to the incremental collection set 755 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; } 756 757 // Add information about hr to the aggregated information for the 758 // incrementally built collection set. 759 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length); 760 761 // Update information about hr in the aggregated information for 762 // the incrementally built collection set. 763 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length); 764 765 private: 766 // Update the incremental cset information when adding a region 767 // (should not be called directly). 768 void add_region_to_incremental_cset_common(HeapRegion* hr); 769 770 public: 771 // Add hr to the LHS of the incremental collection set. 772 void add_region_to_incremental_cset_lhs(HeapRegion* hr); 773 774 // Add hr to the RHS of the incremental collection set. 775 void add_region_to_incremental_cset_rhs(HeapRegion* hr); 776 777 #ifndef PRODUCT 778 void print_collection_set(HeapRegion* list_head, outputStream* st); 779 #endif // !PRODUCT 780 781 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; } 782 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; } 783 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; } 784 785 bool during_initial_mark_pause() { return _during_initial_mark_pause; } 786 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; } 787 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; } 788 789 // This sets the initiate_conc_mark_if_possible() flag to start a 790 // new cycle, as long as we are not already in one. It's best if it 791 // is called during a safepoint when the test whether a cycle is in 792 // progress or not is stable. 793 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause); 794 795 // This is called at the very beginning of an evacuation pause (it 796 // has to be the first thing that the pause does). If 797 // initiate_conc_mark_if_possible() is true, and the concurrent 798 // marking thread has completed its work during the previous cycle, 799 // it will set during_initial_mark_pause() to so that the pause does 800 // the initial-mark work and start a marking cycle. 801 void decide_on_conc_mark_initiation(); 802 803 // If an expansion would be appropriate, because recent GC overhead had 804 // exceeded the desired limit, return an amount to expand by. 805 size_t expansion_amount(); 806 807 // Print tracing information. 808 void print_tracing_info() const; 809 810 // Print stats on young survival ratio 811 void print_yg_surv_rate_info() const; 812 813 void finished_recalculating_age_indexes(bool is_survivors) { 814 if (is_survivors) { 815 _survivor_surv_rate_group->finished_recalculating_age_indexes(); 816 } else { 817 _short_lived_surv_rate_group->finished_recalculating_age_indexes(); 818 } 819 // do that for any other surv rate groups 820 } 821 822 bool is_young_list_full() { 823 uint young_list_length = _g1->young_list()->length(); 824 uint young_list_target_length = _young_list_target_length; 825 return young_list_length >= young_list_target_length; 826 } 827 828 bool can_expand_young_list() { 829 uint young_list_length = _g1->young_list()->length(); 830 uint young_list_max_length = _young_list_max_length; 831 return young_list_length < young_list_max_length; 832 } 833 834 uint young_list_max_length() { 835 return _young_list_max_length; 836 } 837 838 bool gcs_are_young() { 839 return _gcs_are_young; 840 } 841 void set_gcs_are_young(bool gcs_are_young) { 842 _gcs_are_young = gcs_are_young; 843 } 844 845 bool adaptive_young_list_length() { 846 return _young_gen_sizer->adaptive_young_list_length(); 847 } 848 849 private: 850 // 851 // Survivor regions policy. 852 // 853 854 // Current tenuring threshold, set to 0 if the collector reaches the 855 // maximum amount of survivors regions. 856 uint _tenuring_threshold; 857 858 // The limit on the number of regions allocated for survivors. 859 uint _max_survivor_regions; 860 861 // For reporting purposes. 862 // The value of _heap_bytes_before_gc is also used to calculate 863 // the cost of copying. 864 865 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC 866 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC 867 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC 868 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC 869 870 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC 871 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC 872 873 // The amount of survivor regions after a collection. 874 uint _recorded_survivor_regions; 875 // List of survivor regions. 876 HeapRegion* _recorded_survivor_head; 877 HeapRegion* _recorded_survivor_tail; 878 879 ageTable _survivors_age_table; 880 881 public: 882 883 inline GCAllocPurpose 884 evacuation_destination(HeapRegion* src_region, uint age, size_t word_sz) { 885 if (age < _tenuring_threshold && src_region->is_young()) { 886 return GCAllocForSurvived; 887 } else { 888 return GCAllocForTenured; 889 } 890 } 891 892 inline bool track_object_age(GCAllocPurpose purpose) { 893 return purpose == GCAllocForSurvived; 894 } 895 896 static const uint REGIONS_UNLIMITED = (uint) -1; 897 898 uint max_regions(int purpose); 899 900 // The limit on regions for a particular purpose is reached. 901 void note_alloc_region_limit_reached(int purpose) { 902 if (purpose == GCAllocForSurvived) { 903 _tenuring_threshold = 0; 904 } 905 } 906 907 void note_start_adding_survivor_regions() { 908 _survivor_surv_rate_group->start_adding_regions(); 909 } 910 911 void note_stop_adding_survivor_regions() { 912 _survivor_surv_rate_group->stop_adding_regions(); 913 } 914 915 void record_survivor_regions(uint regions, 916 HeapRegion* head, 917 HeapRegion* tail) { 918 _recorded_survivor_regions = regions; 919 _recorded_survivor_head = head; 920 _recorded_survivor_tail = tail; 921 } 922 923 uint recorded_survivor_regions() { 924 return _recorded_survivor_regions; 925 } 926 927 void record_thread_age_table(ageTable* age_table) { 928 _survivors_age_table.merge_par(age_table); 929 } 930 931 void update_max_gc_locker_expansion(); 932 933 // Calculates survivor space parameters. 934 void update_survivors_policy(); 935 936 }; 937 938 // This should move to some place more general... 939 940 // If we have "n" measurements, and we've kept track of their "sum" and the 941 // "sum_of_squares" of the measurements, this returns the variance of the 942 // sequence. 943 inline double variance(int n, double sum_of_squares, double sum) { 944 double n_d = (double)n; 945 double avg = sum/n_d; 946 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d; 947 } 948 949 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP