1 /*
2 * Copyright (c) 2001, 2015, 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
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
27
28 #include "gc/g1/collectionSetChooser.hpp"
29 #include "gc/g1/g1CollectorState.hpp"
30 #include "gc/g1/g1GCPhaseTimes.hpp"
31 #include "gc/g1/g1InCSetState.hpp"
32 #include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"
33 #include "gc/g1/g1MMUTracker.hpp"
34 #include "gc/g1/g1Predictions.hpp"
35 #include "gc/shared/collectorPolicy.hpp"
36 #include "utilities/pair.hpp"
37
38 // A G1CollectorPolicy makes policy decisions that determine the
39 // characteristics of the collector. Examples include:
40 // * choice of collection set.
41 // * when to collect.
42
43 class HeapRegion;
44 class CollectionSetChooser;
45 class G1IHOPControl;
46
47 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses
48 // (the latter may contain non-young regions - i.e. regions that are
49 // technically in old) while TraceOldGenTime collects data about full GCs.
50 class TraceYoungGenTimeData : public CHeapObj<mtGC> {
51 private:
52 unsigned _young_pause_num;
53 unsigned _mixed_pause_num;
54
55 NumberSeq _all_stop_world_times_ms;
56 NumberSeq _all_yield_times_ms;
57
58 NumberSeq _total;
59 NumberSeq _other;
60 NumberSeq _root_region_scan_wait;
61 NumberSeq _parallel;
62 NumberSeq _ext_root_scan;
63 NumberSeq _satb_filtering;
64 NumberSeq _update_rs;
65 NumberSeq _scan_rs;
66 NumberSeq _obj_copy;
67 NumberSeq _termination;
68 NumberSeq _parallel_other;
69 NumberSeq _clear_ct;
70
71 void print_summary(const char* str, const NumberSeq* seq) const;
72 void print_summary_sd(const char* str, const NumberSeq* seq) const;
73
74 public:
75 TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
76 void record_start_collection(double time_to_stop_the_world_ms);
77 void record_yield_time(double yield_time_ms);
78 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
79 void increment_young_collection_count();
80 void increment_mixed_collection_count();
81 void print() const;
82 };
83
84 class TraceOldGenTimeData : public CHeapObj<mtGC> {
85 private:
86 NumberSeq _all_full_gc_times;
87
88 public:
89 void record_full_collection(double full_gc_time_ms);
90 void print() const;
91 };
92
93 // There are three command line options related to the young gen size:
94 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
95 // just a short form for NewSize==MaxNewSize). G1 will use its internal
96 // heuristics to calculate the actual young gen size, so these options
97 // basically only limit the range within which G1 can pick a young gen
98 // size. Also, these are general options taking byte sizes. G1 will
99 // internally work with a number of regions instead. So, some rounding
100 // will occur.
101 //
102 // If nothing related to the the young gen size is set on the command
103 // line we should allow the young gen to be between G1NewSizePercent
104 // and G1MaxNewSizePercent of the heap size. This means that every time
105 // the heap size changes, the limits for the young gen size will be
106 // recalculated.
107 //
108 // If only -XX:NewSize is set we should use the specified value as the
109 // minimum size for young gen. Still using G1MaxNewSizePercent of the
110 // heap as maximum.
111 //
112 // If only -XX:MaxNewSize is set we should use the specified value as the
113 // maximum size for young gen. Still using G1NewSizePercent of the heap
114 // as minimum.
115 //
116 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
117 // No updates when the heap size changes. There is a special case when
118 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
119 // different heuristic for calculating the collection set when we do mixed
120 // collection.
121 //
122 // If only -XX:NewRatio is set we should use the specified ratio of the heap
123 // as both min and max. This will be interpreted as "fixed" just like the
124 // NewSize==MaxNewSize case above. But we will update the min and max
125 // every time the heap size changes.
126 //
127 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
128 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
129 class G1YoungGenSizer : public CHeapObj<mtGC> {
130 private:
131 enum SizerKind {
132 SizerDefaults,
133 SizerNewSizeOnly,
134 SizerMaxNewSizeOnly,
135 SizerMaxAndNewSize,
136 SizerNewRatio
137 };
138 SizerKind _sizer_kind;
139 uint _min_desired_young_length;
140 uint _max_desired_young_length;
141 bool _adaptive_size;
142 uint calculate_default_min_length(uint new_number_of_heap_regions);
143 uint calculate_default_max_length(uint new_number_of_heap_regions);
144
145 // Update the given values for minimum and maximum young gen length in regions
146 // given the number of heap regions depending on the kind of sizing algorithm.
147 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
148
149 public:
150 G1YoungGenSizer();
151 // Calculate the maximum length of the young gen given the number of regions
152 // depending on the sizing algorithm.
153 uint max_young_length(uint number_of_heap_regions);
154
155 void heap_size_changed(uint new_number_of_heap_regions);
156 uint min_desired_young_length() {
157 return _min_desired_young_length;
158 }
159 uint max_desired_young_length() {
160 return _max_desired_young_length;
161 }
162 bool adaptive_young_list_length() const {
163 return _adaptive_size;
164 }
165 };
166
167 class G1CollectorPolicy: public CollectorPolicy {
168 private:
169 G1IHOPControl* _ihop_control;
170
171 G1IHOPControl* create_ihop_control() const;
172 // Update the IHOP control with necessary statistics.
173 void update_ihop_prediction(double mutator_time_s,
174 size_t mutator_alloc_bytes,
175 size_t young_gen_size);
176 void report_ihop_statistics();
177
178 G1Predictions _predictor;
179
180 double get_new_prediction(TruncatedSeq const* seq) const;
181
182 // either equal to the number of parallel threads, if ParallelGCThreads
183 // has been set, or 1 otherwise
184 int _parallel_gc_threads;
185
186 // The number of GC threads currently active.
187 uintx _no_of_gc_threads;
188
189 G1MMUTracker* _mmu_tracker;
190
191 void initialize_alignments();
192 void initialize_flags();
193
194 CollectionSetChooser* _collectionSetChooser;
195
196 double _full_collection_start_sec;
197 uint _cur_collection_pause_used_regions_at_start;
198
199 // These exclude marking times.
200 TruncatedSeq* _recent_gc_times_ms;
201
202 TruncatedSeq* _concurrent_mark_remark_times_ms;
203 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
204
205 TraceYoungGenTimeData _trace_young_gen_time_data;
206 TraceOldGenTimeData _trace_old_gen_time_data;
207
208 double _stop_world_start;
209
210 uint _young_list_target_length;
211 uint _young_list_fixed_length;
212
213 // The max number of regions we can extend the eden by while the GC
214 // locker is active. This should be >= _young_list_target_length;
215 uint _young_list_max_length;
216
217 SurvRateGroup* _short_lived_surv_rate_group;
218 SurvRateGroup* _survivor_surv_rate_group;
219 // add here any more surv rate groups
220
221 double _gc_overhead_perc;
222
223 double _reserve_factor;
224 uint _reserve_regions;
225
226 enum PredictionConstants {
227 TruncatedSeqLength = 10,
228 NumPrevPausesForHeuristics = 10
229 };
230
231 TruncatedSeq* _alloc_rate_ms_seq;
232 double _prev_collection_pause_end_ms;
233
234 TruncatedSeq* _rs_length_diff_seq;
235 TruncatedSeq* _cost_per_card_ms_seq;
236 TruncatedSeq* _cost_scan_hcc_seq;
237 TruncatedSeq* _young_cards_per_entry_ratio_seq;
238 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
239 TruncatedSeq* _cost_per_entry_ms_seq;
240 TruncatedSeq* _mixed_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* _rs_lengths_seq;
248
249 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
250
251 G1YoungGenSizer* _young_gen_sizer;
252
253 uint _eden_cset_region_length;
254 uint _survivor_cset_region_length;
255 uint _old_cset_region_length;
256
257 void init_cset_region_lengths(uint eden_cset_region_length,
258 uint survivor_cset_region_length);
259
260 uint eden_cset_region_length() const { return _eden_cset_region_length; }
261 uint survivor_cset_region_length() const { return _survivor_cset_region_length; }
262 uint old_cset_region_length() const { return _old_cset_region_length; }
263
264 uint _free_regions_at_end_of_collection;
265
266 size_t _recorded_rs_lengths;
267 size_t _max_rs_lengths;
268
269 size_t _rs_lengths_prediction;
270
271 #ifndef PRODUCT
272 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
273 #endif // PRODUCT
274
275 void adjust_concurrent_refinement(double update_rs_time,
276 double update_rs_processed_buffers,
277 double goal_ms);
278
279 uintx no_of_gc_threads() { return _no_of_gc_threads; }
280 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
281
282 double _pause_time_target_ms;
283
284 size_t _pending_cards;
285
286 // The amount of allocated bytes in old gen during the last mutator and the following
287 // young GC phase.
288 size_t _bytes_allocated_in_old_since_last_gc;
289
290 G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;
291 public:
292 const G1Predictions& predictor() const { return _predictor; }
293
294 // Add the given number of bytes to the total number of allocated bytes in the old gen.
295 void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }
296
297 // Accessors
298
299 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
300 hr->set_eden();
301 hr->install_surv_rate_group(_short_lived_surv_rate_group);
302 hr->set_young_index_in_cset(young_index_in_cset);
303 }
304
305 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
306 assert(hr->is_survivor(), "pre-condition");
307 hr->install_surv_rate_group(_survivor_surv_rate_group);
308 hr->set_young_index_in_cset(young_index_in_cset);
309 }
310
311 #ifndef PRODUCT
312 bool verify_young_ages();
313 #endif // PRODUCT
314
315 void record_max_rs_lengths(size_t rs_lengths) {
316 _max_rs_lengths = rs_lengths;
317 }
318
319 size_t predict_rs_length_diff() const;
320
321 double predict_alloc_rate_ms() const;
322
323 double predict_cost_per_card_ms() const;
324
325 double predict_scan_hcc_ms() const;
326
327 double predict_rs_update_time_ms(size_t pending_cards) const;
328
329 double predict_young_cards_per_entry_ratio() const;
330
331 double predict_mixed_cards_per_entry_ratio() const;
332
333 size_t predict_young_card_num(size_t rs_length) const;
334
335 size_t predict_non_young_card_num(size_t rs_length) const;
336
337 double predict_rs_scan_time_ms(size_t card_num) const;
338
339 double predict_mixed_rs_scan_time_ms(size_t card_num) const;
340
341 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const;
342
343 double predict_object_copy_time_ms(size_t bytes_to_copy) const;
344
345 double predict_constant_other_time_ms() const;
346
347 double predict_young_other_time_ms(size_t young_num) const;
348
349 double predict_non_young_other_time_ms(size_t non_young_num) const;
350
351 double predict_base_elapsed_time_ms(size_t pending_cards) const;
352 double predict_base_elapsed_time_ms(size_t pending_cards,
353 size_t scanned_cards) const;
354 size_t predict_bytes_to_copy(HeapRegion* hr) const;
355 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc) const;
356
357 void set_recorded_rs_lengths(size_t rs_lengths);
358
359 uint cset_region_length() const { return young_cset_region_length() +
360 old_cset_region_length(); }
361 uint young_cset_region_length() const { return eden_cset_region_length() +
362 survivor_cset_region_length(); }
363
364 double predict_survivor_regions_evac_time() const;
365
366 bool should_update_surv_rate_group_predictors() {
367 return collector_state()->last_gc_was_young() && !collector_state()->in_marking_window();
368 }
369
370 void cset_regions_freed() {
371 bool update = should_update_surv_rate_group_predictors();
372
373 _short_lived_surv_rate_group->all_surviving_words_recorded(update);
374 _survivor_surv_rate_group->all_surviving_words_recorded(update);
375 }
376
377 G1MMUTracker* mmu_tracker() {
378 return _mmu_tracker;
379 }
380
381 const G1MMUTracker* mmu_tracker() const {
382 return _mmu_tracker;
383 }
384
385 double max_pause_time_ms() const {
386 return _mmu_tracker->max_gc_time() * 1000.0;
387 }
388
389 double predict_remark_time_ms() const;
390
391 double predict_cleanup_time_ms() const;
392
393 // Returns an estimate of the survival rate of the region at yg-age
394 // "yg_age".
395 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const;
396
397 double predict_yg_surv_rate(int age) const;
398
399 double accum_yg_surv_rate_pred(int age) const;
400
401 protected:
402 virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;
403 virtual double other_time_ms(double pause_time_ms) const;
404
405 double young_other_time_ms() const;
406 double non_young_other_time_ms() const;
407 double constant_other_time_ms(double pause_time_ms) const;
408
409 private:
410 // Statistics kept per GC stoppage, pause or full.
411 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
412
413 // Add a new GC of the given duration and end time to the record.
414 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
415
416 // The head of the list (via "next_in_collection_set()") representing the
417 // current collection set. Set from the incrementally built collection
418 // set at the start of the pause.
419 HeapRegion* _collection_set;
420
421 // The number of bytes in the collection set before the pause. Set from
422 // the incrementally built collection set at the start of an evacuation
423 // pause, and incremented in finalize_old_cset_part() when adding old regions
424 // (if any) to the collection set.
425 size_t _collection_set_bytes_used_before;
426
427 // The number of bytes copied during the GC.
428 size_t _bytes_copied_during_gc;
429
430 // The associated information that is maintained while the incremental
431 // collection set is being built with young regions. Used to populate
432 // the recorded info for the evacuation pause.
433
434 enum CSetBuildType {
435 Active, // We are actively building the collection set
436 Inactive // We are not actively building the collection set
437 };
438
439 CSetBuildType _inc_cset_build_state;
440
441 // The head of the incrementally built collection set.
442 HeapRegion* _inc_cset_head;
443
444 // The tail of the incrementally built collection set.
445 HeapRegion* _inc_cset_tail;
446
447 // The number of bytes in the incrementally built collection set.
448 // Used to set _collection_set_bytes_used_before at the start of
449 // an evacuation pause.
450 size_t _inc_cset_bytes_used_before;
451
452 // Used to record the highest end of heap region in collection set
453 HeapWord* _inc_cset_max_finger;
454
455 // The RSet lengths recorded for regions in the CSet. It is updated
456 // by the thread that adds a new region to the CSet. We assume that
457 // only one thread can be allocating a new CSet region (currently,
458 // it does so after taking the Heap_lock) hence no need to
459 // synchronize updates to this field.
460 size_t _inc_cset_recorded_rs_lengths;
461
462 // A concurrent refinement thread periodically samples the young
463 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
464 // the RSets grow. Instead of having to synchronize updates to that
465 // field we accumulate them in this field and add it to
466 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
467 ssize_t _inc_cset_recorded_rs_lengths_diffs;
468
469 // The predicted elapsed time it will take to collect the regions in
470 // the CSet. This is updated by the thread that adds a new region to
471 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
472 // MT-safety assumptions.
473 double _inc_cset_predicted_elapsed_time_ms;
474
475 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
476 double _inc_cset_predicted_elapsed_time_ms_diffs;
477
478 // Stash a pointer to the g1 heap.
479 G1CollectedHeap* _g1;
480
481 G1GCPhaseTimes* _phase_times;
482
483 // The ratio of gc time to elapsed time, computed over recent pauses.
484 double _recent_avg_pause_time_ratio;
485
486 double recent_avg_pause_time_ratio() const {
487 return _recent_avg_pause_time_ratio;
488 }
489
490 // This set of variables tracks the collector efficiency, in order to
491 // determine whether we should initiate a new marking.
492 double _cur_mark_stop_world_time_ms;
493 double _mark_remark_start_sec;
494 double _mark_cleanup_start_sec;
495
496 // Updates the internal young list maximum and target lengths. Returns the
497 // unbounded young list target length.
498 uint update_young_list_max_and_target_length();
499 uint update_young_list_max_and_target_length(size_t rs_lengths);
500
501 // Update the young list target length either by setting it to the
502 // desired fixed value or by calculating it using G1's pause
503 // prediction model. If no rs_lengths parameter is passed, predict
504 // the RS lengths using the prediction model, otherwise use the
505 // given rs_lengths as the prediction.
506 // Returns the unbounded young list target length.
507 uint update_young_list_target_length(size_t rs_lengths);
508
509 // Calculate and return the minimum desired young list target
510 // length. This is the minimum desired young list length according
511 // to the user's inputs.
512 uint calculate_young_list_desired_min_length(uint base_min_length) const;
513
514 // Calculate and return the maximum desired young list target
515 // length. This is the maximum desired young list length according
516 // to the user's inputs.
517 uint calculate_young_list_desired_max_length() const;
518
519 // Calculate and return the maximum young list target length that
520 // can fit into the pause time goal. The parameters are: rs_lengths
521 // represent the prediction of how large the young RSet lengths will
522 // be, base_min_length is the already existing number of regions in
523 // the young list, min_length and max_length are the desired min and
524 // max young list length according to the user's inputs.
525 uint calculate_young_list_target_length(size_t rs_lengths,
526 uint base_min_length,
527 uint desired_min_length,
528 uint desired_max_length) const;
529
530 // Result of the bounded_young_list_target_length() method, containing both the
531 // bounded as well as the unbounded young list target lengths in this order.
532 typedef Pair<uint, uint, StackObj> YoungTargetLengths;
533 YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;
534
535 void update_rs_lengths_prediction();
536 void update_rs_lengths_prediction(size_t prediction);
537
538 // Calculate and return chunk size (in number of regions) for parallel
539 // concurrent mark cleanup.
540 uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const;
541
542 // Check whether a given young length (young_length) fits into the
543 // given target pause time and whether the prediction for the amount
544 // of objects to be copied for the given length will fit into the
545 // given free space (expressed by base_free_regions). It is used by
546 // calculate_young_list_target_length().
547 bool predict_will_fit(uint young_length, double base_time_ms,
548 uint base_free_regions, double target_pause_time_ms) const;
549
550 // Calculate the minimum number of old regions we'll add to the CSet
551 // during a mixed GC.
552 uint calc_min_old_cset_length() const;
553
554 // Calculate the maximum number of old regions we'll add to the CSet
555 // during a mixed GC.
556 uint calc_max_old_cset_length() const;
557
558 // Returns the given amount of uncollected reclaimable space
559 // as a percentage of the current heap capacity.
560 double reclaimable_bytes_perc(size_t reclaimable_bytes) const;
561
562 // Sets up marking if proper conditions are met.
563 void maybe_start_marking();
564
565 // The kind of STW pause.
566 enum PauseKind {
567 FullGC,
568 YoungOnlyGC,
569 MixedGC,
570 LastYoungGC,
571 InitialMarkGC,
572 Cleanup,
573 Remark
574 };
575
576 // Calculate PauseKind from internal state.
577 PauseKind young_gc_pause_kind() const;
578 // Record the given STW pause with the given start and end times (in s).
579 void record_pause(PauseKind kind, double start, double end);
580 // Indicate that we aborted marking before doing any mixed GCs.
581 void abort_time_to_mixed_tracking();
582 public:
583
584 G1CollectorPolicy();
585
586 virtual ~G1CollectorPolicy();
587
588 virtual G1CollectorPolicy* as_g1_policy() { return this; }
589
590 G1CollectorState* collector_state() const;
591
592 G1GCPhaseTimes* phase_times() const { return _phase_times; }
593
594 // Check the current value of the young list RSet lengths and
595 // compare it against the last prediction. If the current value is
596 // higher, recalculate the young list target length prediction.
597 void revise_young_list_target_length_if_necessary();
598
599 // This should be called after the heap is resized.
600 void record_new_heap_size(uint new_number_of_regions);
601
602 void init();
603
604 virtual void note_gc_start(uint num_active_workers);
605
606 // Create jstat counters for the policy.
607 virtual void initialize_gc_policy_counters();
608
609 virtual HeapWord* mem_allocate_work(size_t size,
610 bool is_tlab,
611 bool* gc_overhead_limit_was_exceeded);
612
613 // This method controls how a collector handles one or more
614 // of its generations being fully allocated.
615 virtual HeapWord* satisfy_failed_allocation(size_t size,
616 bool is_tlab);
617
618 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
619
620 bool about_to_start_mixed_phase() const;
621
622 // Record the start and end of an evacuation pause.
623 void record_collection_pause_start(double start_time_sec);
624 void record_collection_pause_end(double pause_time_ms, size_t cards_scanned);
625
626 // Record the start and end of a full collection.
627 void record_full_collection_start();
628 void record_full_collection_end();
629
630 // Must currently be called while the world is stopped.
631 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
632
633 // Record start and end of remark.
634 void record_concurrent_mark_remark_start();
635 void record_concurrent_mark_remark_end();
636
637 // Record start, end, and completion of cleanup.
638 void record_concurrent_mark_cleanup_start();
639 void record_concurrent_mark_cleanup_end();
640 void record_concurrent_mark_cleanup_completed();
641
642 // Records the information about the heap size for reporting in
643 // print_detailed_heap_transition
644 void record_heap_size_info_at_start(bool full);
645
646 // Print heap sizing transition (with less and more detail).
647
648 void print_heap_transition(size_t bytes_before) const;
649 void print_heap_transition() const;
650 void print_detailed_heap_transition(bool full = false) const;
651
652 virtual void print_phases(double pause_time_sec);
653
654 void record_stop_world_start();
655 void record_concurrent_pause();
656
657 // Record how much space we copied during a GC. This is typically
658 // called when a GC alloc region is being retired.
659 void record_bytes_copied_during_gc(size_t bytes) {
660 _bytes_copied_during_gc += bytes;
661 }
662
663 // The amount of space we copied during a GC.
664 size_t bytes_copied_during_gc() const {
665 return _bytes_copied_during_gc;
666 }
667
668 size_t collection_set_bytes_used_before() const {
669 return _collection_set_bytes_used_before;
670 }
671
672 // Determine whether there are candidate regions so that the
673 // next GC should be mixed. The two action strings are used
674 // in the ergo output when the method returns true or false.
675 bool next_gc_should_be_mixed(const char* true_action_str,
676 const char* false_action_str) const;
677
678 // Choose a new collection set. Marks the chosen regions as being
679 // "in_collection_set", and links them together. The head and number of
680 // the collection set are available via access methods.
681 double finalize_young_cset_part(double target_pause_time_ms);
682 virtual void finalize_old_cset_part(double time_remaining_ms);
683
684 // The head of the list (via "next_in_collection_set()") representing the
685 // current collection set.
686 HeapRegion* collection_set() { return _collection_set; }
687
688 void clear_collection_set() { _collection_set = NULL; }
689
690 // Add old region "hr" to the CSet.
691 void add_old_region_to_cset(HeapRegion* hr);
692
693 // Incremental CSet Support
694
695 // The head of the incrementally built collection set.
696 HeapRegion* inc_cset_head() { return _inc_cset_head; }
697
698 // The tail of the incrementally built collection set.
699 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
700
701 // Initialize incremental collection set info.
702 void start_incremental_cset_building();
703
704 // Perform any final calculations on the incremental CSet fields
705 // before we can use them.
706 void finalize_incremental_cset_building();
707
708 void clear_incremental_cset() {
709 _inc_cset_head = NULL;
710 _inc_cset_tail = NULL;
711 }
712
713 // Stop adding regions to the incremental collection set
714 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
715
716 // Add information about hr to the aggregated information for the
717 // incrementally built collection set.
718 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
719
720 // Update information about hr in the aggregated information for
721 // the incrementally built collection set.
722 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
723
724 private:
725 // Update the incremental cset information when adding a region
726 // (should not be called directly).
727 void add_region_to_incremental_cset_common(HeapRegion* hr);
728
729 public:
730 // Add hr to the LHS of the incremental collection set.
731 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
732
733 // Add hr to the RHS of the incremental collection set.
734 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
735
736 #ifndef PRODUCT
737 void print_collection_set(HeapRegion* list_head, outputStream* st);
738 #endif // !PRODUCT
739
740 // This sets the initiate_conc_mark_if_possible() flag to start a
741 // new cycle, as long as we are not already in one. It's best if it
742 // is called during a safepoint when the test whether a cycle is in
743 // progress or not is stable.
744 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
745
746 // This is called at the very beginning of an evacuation pause (it
747 // has to be the first thing that the pause does). If
748 // initiate_conc_mark_if_possible() is true, and the concurrent
749 // marking thread has completed its work during the previous cycle,
750 // it will set during_initial_mark_pause() to so that the pause does
751 // the initial-mark work and start a marking cycle.
752 void decide_on_conc_mark_initiation();
753
754 // If an expansion would be appropriate, because recent GC overhead had
755 // exceeded the desired limit, return an amount to expand by.
756 virtual size_t expansion_amount() const;
757
758 // Print tracing information.
759 void print_tracing_info() const;
760
761 // Print stats on young survival ratio
762 void print_yg_surv_rate_info() const;
763
764 void finished_recalculating_age_indexes(bool is_survivors) {
765 if (is_survivors) {
766 _survivor_surv_rate_group->finished_recalculating_age_indexes();
767 } else {
768 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
769 }
770 // do that for any other surv rate groups
771 }
772
773 size_t young_list_target_length() const { return _young_list_target_length; }
774
775 bool is_young_list_full() const;
776
777 bool can_expand_young_list() const;
778
779 uint young_list_max_length() const {
780 return _young_list_max_length;
781 }
782
783 bool adaptive_young_list_length() const {
784 return _young_gen_sizer->adaptive_young_list_length();
785 }
786
787 private:
788 //
789 // Survivor regions policy.
790 //
791
792 // Current tenuring threshold, set to 0 if the collector reaches the
793 // maximum amount of survivors regions.
794 uint _tenuring_threshold;
795
796 // The limit on the number of regions allocated for survivors.
797 uint _max_survivor_regions;
798
799 // For reporting purposes.
800 // The value of _heap_bytes_before_gc is also used to calculate
801 // the cost of copying.
802
803 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC
804 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC
805 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC
806 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC
807
808 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC
809 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC
810
811 // The amount of survivor regions after a collection.
812 uint _recorded_survivor_regions;
813 // List of survivor regions.
814 HeapRegion* _recorded_survivor_head;
815 HeapRegion* _recorded_survivor_tail;
816
817 ageTable _survivors_age_table;
818
819 public:
820 uint tenuring_threshold() const { return _tenuring_threshold; }
821
822 static const uint REGIONS_UNLIMITED = (uint) -1;
823
824 uint max_regions(InCSetState dest) const {
825 switch (dest.value()) {
826 case InCSetState::Young:
827 return _max_survivor_regions;
828 case InCSetState::Old:
829 return REGIONS_UNLIMITED;
830 default:
831 assert(false, "Unknown dest state: " CSETSTATE_FORMAT, dest.value());
832 break;
833 }
834 // keep some compilers happy
835 return 0;
836 }
837
838 void note_start_adding_survivor_regions() {
839 _survivor_surv_rate_group->start_adding_regions();
840 }
841
842 void note_stop_adding_survivor_regions() {
843 _survivor_surv_rate_group->stop_adding_regions();
844 }
845
846 void record_survivor_regions(uint regions,
847 HeapRegion* head,
848 HeapRegion* tail) {
849 _recorded_survivor_regions = regions;
850 _recorded_survivor_head = head;
851 _recorded_survivor_tail = tail;
852 }
853
854 uint recorded_survivor_regions() const {
855 return _recorded_survivor_regions;
856 }
857
858 void record_age_table(ageTable* age_table) {
859 _survivors_age_table.merge(age_table);
860 }
861
862 void update_max_gc_locker_expansion();
863
864 // Calculates survivor space parameters.
865 void update_survivors_policy();
866
867 virtual void post_heap_initialize();
868 };
869
870 #endif // SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP