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.
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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/g1Allocator.hpp"
30 #include "gc_implementation/g1/g1MMUTracker.hpp"
31 #include "memory/collectorPolicy.hpp"
32
33 // A G1CollectorPolicy makes policy decisions that determine the
34 // characteristics of the collector. Examples include:
35 // * choice of collection set.
36 // * when to collect.
37
38 class HeapRegion;
39 class CollectionSetChooser;
40 class G1GCPhaseTimes;
41
42 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses
43 // (the latter may contain non-young regions - i.e. regions that are
44 // technically in old) while TraceOldGenTime collects data about full GCs.
45 class TraceYoungGenTimeData : public CHeapObj<mtGC> {
46 private:
47 unsigned _young_pause_num;
48 unsigned _mixed_pause_num;
49
50 NumberSeq _all_stop_world_times_ms;
51 NumberSeq _all_yield_times_ms;
52
53 NumberSeq _total;
54 NumberSeq _other;
55 NumberSeq _root_region_scan_wait;
56 NumberSeq _parallel;
57 NumberSeq _ext_root_scan;
58 NumberSeq _satb_filtering;
59 NumberSeq _update_rs;
60 NumberSeq _scan_rs;
61 NumberSeq _obj_copy;
62 NumberSeq _termination;
63 NumberSeq _parallel_other;
64 NumberSeq _clear_ct;
65 NumberSeq _expand_heap;
66
67 void print_summary(const char* str, const NumberSeq* seq) const;
68 void print_summary_sd(const char* str, const NumberSeq* seq) const;
69
70 public:
71 TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
72 void record_start_collection(double time_to_stop_the_world_ms);
73 void record_yield_time(double yield_time_ms);
74 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
75 void increment_young_collection_count();
76 void increment_mixed_collection_count();
77 void print() const;
78 };
79
80 class TraceOldGenTimeData : public CHeapObj<mtGC> {
81 private:
82 NumberSeq _all_full_gc_times;
83
84 public:
85 void record_full_collection(double full_gc_time_ms);
86 void print() const;
87 };
88
89 // There are three command line options related to the young gen size:
90 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
91 // just a short form for NewSize==MaxNewSize). G1 will use its internal
92 // heuristics to calculate the actual young gen size, so these options
93 // basically only limit the range within which G1 can pick a young gen
94 // size. Also, these are general options taking byte sizes. G1 will
95 // internally work with a number of regions instead. So, some rounding
96 // will occur.
97 //
98 // If nothing related to the the young gen size is set on the command
99 // line we should allow the young gen to be between G1NewSizePercent
100 // and G1MaxNewSizePercent of the heap size. This means that every time
101 // the heap size changes, the limits for the young gen size will be
102 // recalculated.
103 //
104 // If only -XX:NewSize is set we should use the specified value as the
105 // minimum size for young gen. Still using G1MaxNewSizePercent of the
106 // heap as maximum.
107 //
108 // If only -XX:MaxNewSize is set we should use the specified value as the
109 // maximum size for young gen. Still using G1NewSizePercent of the heap
110 // as minimum.
111 //
112 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
113 // No updates when the heap size changes. There is a special case when
114 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
115 // different heuristic for calculating the collection set when we do mixed
116 // collection.
117 //
118 // If only -XX:NewRatio is set we should use the specified ratio of the heap
119 // as both min and max. This will be interpreted as "fixed" just like the
120 // NewSize==MaxNewSize case above. But we will update the min and max
121 // every time the heap size changes.
122 //
123 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
124 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
125 class G1YoungGenSizer : public CHeapObj<mtGC> {
126 private:
127 enum SizerKind {
128 SizerDefaults,
129 SizerNewSizeOnly,
130 SizerMaxNewSizeOnly,
131 SizerMaxAndNewSize,
132 SizerNewRatio
133 };
134 SizerKind _sizer_kind;
135 uint _min_desired_young_length;
136 uint _max_desired_young_length;
137 bool _adaptive_size;
138 uint calculate_default_min_length(uint new_number_of_heap_regions);
139 uint calculate_default_max_length(uint new_number_of_heap_regions);
140
141 // Update the given values for minimum and maximum young gen length in regions
142 // given the number of heap regions depending on the kind of sizing algorithm.
143 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
144
145 public:
146 G1YoungGenSizer();
147 // Calculate the maximum length of the young gen given the number of regions
148 // depending on the sizing algorithm.
149 uint max_young_length(uint number_of_heap_regions);
150
151 void heap_size_changed(uint new_number_of_heap_regions);
152 uint min_desired_young_length() {
153 return _min_desired_young_length;
154 }
155 uint max_desired_young_length() {
156 return _max_desired_young_length;
157 }
158 bool adaptive_young_list_length() {
159 return _adaptive_size;
160 }
161 };
162
163 class G1CollectorPolicy: public CollectorPolicy {
164 private:
165 // either equal to the number of parallel threads, if ParallelGCThreads
166 // has been set, or 1 otherwise
167 int _parallel_gc_threads;
168
169 // The number of GC threads currently active.
170 uintx _no_of_gc_threads;
171
172 enum SomePrivateConstants {
173 NumPrevPausesForHeuristics = 10
174 };
175
176 G1MMUTracker* _mmu_tracker;
177
178 void initialize_alignments();
179 void initialize_flags();
180
181 CollectionSetChooser* _collectionSetChooser;
182
183 double _full_collection_start_sec;
184 uint _cur_collection_pause_used_regions_at_start;
185
186 // These exclude marking times.
187 TruncatedSeq* _recent_gc_times_ms;
188
189 TruncatedSeq* _concurrent_mark_remark_times_ms;
190 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
191
192 TraceYoungGenTimeData _trace_young_gen_time_data;
193 TraceOldGenTimeData _trace_old_gen_time_data;
194
195 double _stop_world_start;
196
197 // indicates whether we are in young or mixed GC mode
198 bool _gcs_are_young;
199
200 uint _young_list_target_length;
201 uint _young_list_fixed_length;
202
203 // The max number of regions we can extend the eden by while the GC
204 // locker is active. This should be >= _young_list_target_length;
205 uint _young_list_max_length;
206
207 bool _last_gc_was_young;
208
209 bool _during_marking;
210 bool _in_marking_window;
211 bool _in_marking_window_im;
212
213 SurvRateGroup* _short_lived_surv_rate_group;
214 SurvRateGroup* _survivor_surv_rate_group;
215 // add here any more surv rate groups
216
217 double _gc_overhead_perc;
218
219 double _reserve_factor;
220 uint _reserve_regions;
221
222 bool during_marking() {
223 return _during_marking;
224 }
225
226 enum PredictionConstants {
227 TruncatedSeqLength = 10
228 };
229
230 TruncatedSeq* _alloc_rate_ms_seq;
231 double _prev_collection_pause_end_ms;
232
233 TruncatedSeq* _rs_length_diff_seq;
234 TruncatedSeq* _cost_per_card_ms_seq;
235 TruncatedSeq* _young_cards_per_entry_ratio_seq;
236 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
237 TruncatedSeq* _cost_per_entry_ms_seq;
238 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
239 TruncatedSeq* _cost_per_byte_ms_seq;
240 TruncatedSeq* _constant_other_time_ms_seq;
241 TruncatedSeq* _young_other_cost_per_region_ms_seq;
242 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
243
244 TruncatedSeq* _pending_cards_seq;
245 TruncatedSeq* _rs_lengths_seq;
246
247 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
248
249 G1YoungGenSizer* _young_gen_sizer;
250
251 uint _eden_cset_region_length;
252 uint _survivor_cset_region_length;
253 uint _old_cset_region_length;
254
255 void init_cset_region_lengths(uint eden_cset_region_length,
256 uint survivor_cset_region_length);
257
258 uint eden_cset_region_length() { return _eden_cset_region_length; }
259 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
260 uint old_cset_region_length() { return _old_cset_region_length; }
261
262 uint _free_regions_at_end_of_collection;
263
264 size_t _recorded_rs_lengths;
265 size_t _max_rs_lengths;
266 double _sigma;
267
268 size_t _rs_lengths_prediction;
269
270 double sigma() { return _sigma; }
271
272 // A function that prevents us putting too much stock in small sample
273 // sets. Returns a number between 2.0 and 1.0, depending on the number
274 // of samples. 5 or more samples yields one; fewer scales linearly from
275 // 2.0 at 1 sample to 1.0 at 5.
276 double confidence_factor(int samples) {
277 if (samples > 4) return 1.0;
278 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
279 }
280
281 double get_new_neg_prediction(TruncatedSeq* seq) {
282 return seq->davg() - sigma() * seq->dsd();
283 }
284
285 #ifndef PRODUCT
286 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
287 #endif // PRODUCT
288
289 void adjust_concurrent_refinement(double update_rs_time,
290 double update_rs_processed_buffers,
291 double goal_ms);
292
293 uintx no_of_gc_threads() { return _no_of_gc_threads; }
294 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
295
296 double _pause_time_target_ms;
297
298 size_t _pending_cards;
299
300 public:
301 // Accessors
302
303 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
304 hr->set_eden();
305 hr->install_surv_rate_group(_short_lived_surv_rate_group);
306 hr->set_young_index_in_cset(young_index_in_cset);
307 }
308
309 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
310 assert(hr->is_survivor(), "pre-condition");
311 hr->install_surv_rate_group(_survivor_surv_rate_group);
312 hr->set_young_index_in_cset(young_index_in_cset);
313 }
314
315 #ifndef PRODUCT
316 bool verify_young_ages();
317 #endif // PRODUCT
318
319 double get_new_prediction(TruncatedSeq* seq) {
320 return MAX2(seq->davg() + sigma() * seq->dsd(),
321 seq->davg() * confidence_factor(seq->num()));
322 }
323
324 void record_max_rs_lengths(size_t rs_lengths) {
325 _max_rs_lengths = rs_lengths;
326 }
327
328 size_t predict_rs_length_diff() {
329 return (size_t) get_new_prediction(_rs_length_diff_seq);
330 }
331
332 double predict_alloc_rate_ms() {
333 return get_new_prediction(_alloc_rate_ms_seq);
334 }
335
336 double predict_cost_per_card_ms() {
337 return get_new_prediction(_cost_per_card_ms_seq);
338 }
339
340 double predict_rs_update_time_ms(size_t pending_cards) {
341 return (double) pending_cards * predict_cost_per_card_ms();
342 }
343
344 double predict_young_cards_per_entry_ratio() {
345 return get_new_prediction(_young_cards_per_entry_ratio_seq);
346 }
347
348 double predict_mixed_cards_per_entry_ratio() {
349 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
350 return predict_young_cards_per_entry_ratio();
351 } else {
352 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
353 }
354 }
355
356 size_t predict_young_card_num(size_t rs_length) {
357 return (size_t) ((double) rs_length *
358 predict_young_cards_per_entry_ratio());
359 }
360
361 size_t predict_non_young_card_num(size_t rs_length) {
362 return (size_t) ((double) rs_length *
363 predict_mixed_cards_per_entry_ratio());
364 }
365
366 double predict_rs_scan_time_ms(size_t card_num) {
367 if (gcs_are_young()) {
368 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
369 } else {
370 return predict_mixed_rs_scan_time_ms(card_num);
371 }
372 }
373
374 double predict_mixed_rs_scan_time_ms(size_t card_num) {
375 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
376 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
377 } else {
378 return (double) (card_num *
379 get_new_prediction(_mixed_cost_per_entry_ms_seq));
380 }
381 }
382
383 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
384 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
385 return (1.1 * (double) bytes_to_copy) *
386 get_new_prediction(_cost_per_byte_ms_seq);
387 } else {
388 return (double) bytes_to_copy *
389 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
390 }
391 }
392
393 double predict_object_copy_time_ms(size_t bytes_to_copy) {
394 if (_in_marking_window && !_in_marking_window_im) {
395 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
396 } else {
397 return (double) bytes_to_copy *
398 get_new_prediction(_cost_per_byte_ms_seq);
399 }
400 }
401
402 double predict_constant_other_time_ms() {
403 return get_new_prediction(_constant_other_time_ms_seq);
404 }
405
406 double predict_young_other_time_ms(size_t young_num) {
407 return (double) young_num *
408 get_new_prediction(_young_other_cost_per_region_ms_seq);
409 }
410
411 double predict_non_young_other_time_ms(size_t non_young_num) {
412 return (double) non_young_num *
413 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
414 }
415
416 double predict_base_elapsed_time_ms(size_t pending_cards);
417 double predict_base_elapsed_time_ms(size_t pending_cards,
418 size_t scanned_cards);
419 size_t predict_bytes_to_copy(HeapRegion* hr);
420 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc);
421
422 void set_recorded_rs_lengths(size_t rs_lengths);
423
424 uint cset_region_length() { return young_cset_region_length() +
425 old_cset_region_length(); }
426 uint young_cset_region_length() { return eden_cset_region_length() +
427 survivor_cset_region_length(); }
428
429 double predict_survivor_regions_evac_time();
430
431 void cset_regions_freed() {
432 bool propagate = _last_gc_was_young && !_in_marking_window;
433 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
434 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
435 // also call it on any more surv rate groups
436 }
437
438 G1MMUTracker* mmu_tracker() {
439 return _mmu_tracker;
440 }
441
442 double max_pause_time_ms() {
443 return _mmu_tracker->max_gc_time() * 1000.0;
444 }
445
446 double predict_remark_time_ms() {
447 return get_new_prediction(_concurrent_mark_remark_times_ms);
448 }
449
450 double predict_cleanup_time_ms() {
451 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
452 }
453
454 // Returns an estimate of the survival rate of the region at yg-age
455 // "yg_age".
456 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
457 TruncatedSeq* seq = surv_rate_group->get_seq(age);
458 if (seq->num() == 0)
459 gclog_or_tty->print("BARF! age is %d", age);
460 guarantee( seq->num() > 0, "invariant" );
461 double pred = get_new_prediction(seq);
462 if (pred > 1.0)
463 pred = 1.0;
464 return pred;
465 }
466
467 double predict_yg_surv_rate(int age) {
468 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
469 }
470
471 double accum_yg_surv_rate_pred(int age) {
472 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
473 }
474
475 private:
476 // Statistics kept per GC stoppage, pause or full.
477 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
478
479 // Add a new GC of the given duration and end time to the record.
480 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
481
482 // The head of the list (via "next_in_collection_set()") representing the
483 // current collection set. Set from the incrementally built collection
484 // set at the start of the pause.
485 HeapRegion* _collection_set;
486
487 // The number of bytes in the collection set before the pause. Set from
488 // the incrementally built collection set at the start of an evacuation
489 // pause, and incremented in finalize_cset() when adding old regions
490 // (if any) to the collection set.
491 size_t _collection_set_bytes_used_before;
492
493 // The number of bytes copied during the GC.
494 size_t _bytes_copied_during_gc;
495
496 // The associated information that is maintained while the incremental
497 // collection set is being built with young regions. Used to populate
498 // the recorded info for the evacuation pause.
499
500 enum CSetBuildType {
501 Active, // We are actively building the collection set
502 Inactive // We are not actively building the collection set
503 };
504
505 CSetBuildType _inc_cset_build_state;
506
507 // The head of the incrementally built collection set.
508 HeapRegion* _inc_cset_head;
509
510 // The tail of the incrementally built collection set.
511 HeapRegion* _inc_cset_tail;
512
513 // The number of bytes in the incrementally built collection set.
514 // Used to set _collection_set_bytes_used_before at the start of
515 // an evacuation pause.
516 size_t _inc_cset_bytes_used_before;
517
518 // Used to record the highest end of heap region in collection set
519 HeapWord* _inc_cset_max_finger;
520
521 // The RSet lengths recorded for regions in the CSet. It is updated
522 // by the thread that adds a new region to the CSet. We assume that
523 // only one thread can be allocating a new CSet region (currently,
524 // it does so after taking the Heap_lock) hence no need to
525 // synchronize updates to this field.
526 size_t _inc_cset_recorded_rs_lengths;
527
528 // A concurrent refinement thread periodically samples the young
529 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
530 // the RSets grow. Instead of having to synchronize updates to that
531 // field we accumulate them in this field and add it to
532 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
533 ssize_t _inc_cset_recorded_rs_lengths_diffs;
534
535 // The predicted elapsed time it will take to collect the regions in
536 // the CSet. This is updated by the thread that adds a new region to
537 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
538 // MT-safety assumptions.
539 double _inc_cset_predicted_elapsed_time_ms;
540
541 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
542 double _inc_cset_predicted_elapsed_time_ms_diffs;
543
544 // Stash a pointer to the g1 heap.
545 G1CollectedHeap* _g1;
546
547 G1GCPhaseTimes* _phase_times;
548
549 // The ratio of gc time to elapsed time, computed over recent pauses.
550 double _recent_avg_pause_time_ratio;
551
552 double recent_avg_pause_time_ratio() {
553 return _recent_avg_pause_time_ratio;
554 }
555
556 // At the end of a pause we check the heap occupancy and we decide
557 // whether we will start a marking cycle during the next pause. If
558 // we decide that we want to do that, we will set this parameter to
559 // true. So, this parameter will stay true between the end of a
560 // pause and the beginning of a subsequent pause (not necessarily
561 // the next one, see the comments on the next field) when we decide
562 // that we will indeed start a marking cycle and do the initial-mark
563 // work.
564 volatile bool _initiate_conc_mark_if_possible;
565
566 // If initiate_conc_mark_if_possible() is set at the beginning of a
567 // pause, it is a suggestion that the pause should start a marking
568 // cycle by doing the initial-mark work. However, it is possible
569 // that the concurrent marking thread is still finishing up the
570 // previous marking cycle (e.g., clearing the next marking
571 // bitmap). If that is the case we cannot start a new cycle and
572 // we'll have to wait for the concurrent marking thread to finish
573 // what it is doing. In this case we will postpone the marking cycle
574 // initiation decision for the next pause. When we eventually decide
575 // to start a cycle, we will set _during_initial_mark_pause which
576 // will stay true until the end of the initial-mark pause and it's
577 // the condition that indicates that a pause is doing the
578 // initial-mark work.
579 volatile bool _during_initial_mark_pause;
580
581 bool _last_young_gc;
582
583 // This set of variables tracks the collector efficiency, in order to
584 // determine whether we should initiate a new marking.
585 double _cur_mark_stop_world_time_ms;
586 double _mark_remark_start_sec;
587 double _mark_cleanup_start_sec;
588
589 // Update the young list target length either by setting it to the
590 // desired fixed value or by calculating it using G1's pause
591 // prediction model. If no rs_lengths parameter is passed, predict
592 // the RS lengths using the prediction model, otherwise use the
593 // given rs_lengths as the prediction.
594 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
595
596 // Calculate and return the minimum desired young list target
597 // length. This is the minimum desired young list length according
598 // to the user's inputs.
599 uint calculate_young_list_desired_min_length(uint base_min_length);
600
601 // Calculate and return the maximum desired young list target
602 // length. This is the maximum desired young list length according
603 // to the user's inputs.
604 uint calculate_young_list_desired_max_length();
605
606 // Calculate and return the maximum young list target length that
607 // can fit into the pause time goal. The parameters are: rs_lengths
608 // represent the prediction of how large the young RSet lengths will
609 // be, base_min_length is the already existing number of regions in
610 // the young list, min_length and max_length are the desired min and
611 // max young list length according to the user's inputs.
612 uint calculate_young_list_target_length(size_t rs_lengths,
613 uint base_min_length,
614 uint desired_min_length,
615 uint desired_max_length);
616
617 // Calculate and return chunk size (in number of regions) for parallel
618 // concurrent mark cleanup.
619 uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions);
620
621 // Check whether a given young length (young_length) fits into the
622 // given target pause time and whether the prediction for the amount
623 // of objects to be copied for the given length will fit into the
624 // given free space (expressed by base_free_regions). It is used by
625 // calculate_young_list_target_length().
626 bool predict_will_fit(uint young_length, double base_time_ms,
627 uint base_free_regions, double target_pause_time_ms);
628
629 // Calculate the minimum number of old regions we'll add to the CSet
630 // during a mixed GC.
631 uint calc_min_old_cset_length();
632
633 // Calculate the maximum number of old regions we'll add to the CSet
634 // during a mixed GC.
635 uint calc_max_old_cset_length();
636
637 // Returns the given amount of uncollected reclaimable space
638 // as a percentage of the current heap capacity.
639 double reclaimable_bytes_perc(size_t reclaimable_bytes);
640
641 public:
642
643 G1CollectorPolicy();
644
645 virtual G1CollectorPolicy* as_g1_policy() { return this; }
646
647 virtual CollectorPolicy::Name kind() {
648 return CollectorPolicy::G1CollectorPolicyKind;
649 }
650
651 G1GCPhaseTimes* phase_times() const { return _phase_times; }
652
653 // Check the current value of the young list RSet lengths and
654 // compare it against the last prediction. If the current value is
655 // higher, recalculate the young list target length prediction.
656 void revise_young_list_target_length_if_necessary();
657
658 // This should be called after the heap is resized.
659 void record_new_heap_size(uint new_number_of_regions);
660
661 void init();
662
663 // Create jstat counters for the policy.
664 virtual void initialize_gc_policy_counters();
665
666 virtual HeapWord* mem_allocate_work(size_t size,
667 bool is_tlab,
668 bool* gc_overhead_limit_was_exceeded);
669
670 // This method controls how a collector handles one or more
671 // of its generations being fully allocated.
672 virtual HeapWord* satisfy_failed_allocation(size_t size,
673 bool is_tlab);
674
675 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
676
677 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
678
679 // Record the start and end of an evacuation pause.
680 void record_collection_pause_start(double start_time_sec);
681 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info);
682
683 // Record the start and end of a full collection.
684 void record_full_collection_start();
685 void record_full_collection_end();
686
687 // Must currently be called while the world is stopped.
688 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
689
690 // Record start and end of remark.
691 void record_concurrent_mark_remark_start();
692 void record_concurrent_mark_remark_end();
693
694 // Record start, end, and completion of cleanup.
695 void record_concurrent_mark_cleanup_start();
696 void record_concurrent_mark_cleanup_end(uint n_workers);
697 void record_concurrent_mark_cleanup_completed();
698
699 // Records the information about the heap size for reporting in
700 // print_detailed_heap_transition
701 void record_heap_size_info_at_start(bool full);
702
703 // Print heap sizing transition (with less and more detail).
704 void print_heap_transition();
705 void print_detailed_heap_transition(bool full = false);
706
707 void record_stop_world_start();
708 void record_concurrent_pause();
709
710 // Record how much space we copied during a GC. This is typically
711 // called when a GC alloc region is being retired.
712 void record_bytes_copied_during_gc(size_t bytes) {
713 _bytes_copied_during_gc += bytes;
714 }
715
716 // The amount of space we copied during a GC.
717 size_t bytes_copied_during_gc() {
718 return _bytes_copied_during_gc;
719 }
720
721 // Determine whether there are candidate regions so that the
722 // next GC should be mixed. The two action strings are used
723 // in the ergo output when the method returns true or false.
724 bool next_gc_should_be_mixed(const char* true_action_str,
725 const char* false_action_str);
726
727 // Choose a new collection set. Marks the chosen regions as being
728 // "in_collection_set", and links them together. The head and number of
729 // the collection set are available via access methods.
730 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info);
731
732 // The head of the list (via "next_in_collection_set()") representing the
733 // current collection set.
734 HeapRegion* collection_set() { return _collection_set; }
735
736 void clear_collection_set() { _collection_set = NULL; }
737
738 // Add old region "hr" to the CSet.
739 void add_old_region_to_cset(HeapRegion* hr);
740
741 // Incremental CSet Support
742
743 // The head of the incrementally built collection set.
744 HeapRegion* inc_cset_head() { return _inc_cset_head; }
745
746 // The tail of the incrementally built collection set.
747 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
748
749 // Initialize incremental collection set info.
750 void start_incremental_cset_building();
751
752 // Perform any final calculations on the incremental CSet fields
753 // before we can use them.
754 void finalize_incremental_cset_building();
755
756 void clear_incremental_cset() {
757 _inc_cset_head = NULL;
758 _inc_cset_tail = NULL;
759 }
760
761 // Stop adding regions to the incremental collection set
762 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
763
764 // Add information about hr to the aggregated information for the
765 // incrementally built collection set.
766 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
767
768 // Update information about hr in the aggregated information for
769 // the incrementally built collection set.
770 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
771
772 private:
773 // Update the incremental cset information when adding a region
774 // (should not be called directly).
775 void add_region_to_incremental_cset_common(HeapRegion* hr);
776
777 public:
778 // Add hr to the LHS of the incremental collection set.
779 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
780
781 // Add hr to the RHS of the incremental collection set.
782 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
783
784 #ifndef PRODUCT
785 void print_collection_set(HeapRegion* list_head, outputStream* st);
786 #endif // !PRODUCT
787
788 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
789 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
790 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
791
792 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
793 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
794 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
795
796 // This sets the initiate_conc_mark_if_possible() flag to start a
797 // new cycle, as long as we are not already in one. It's best if it
798 // is called during a safepoint when the test whether a cycle is in
799 // progress or not is stable.
800 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
801
802 // This is called at the very beginning of an evacuation pause (it
803 // has to be the first thing that the pause does). If
804 // initiate_conc_mark_if_possible() is true, and the concurrent
805 // marking thread has completed its work during the previous cycle,
806 // it will set during_initial_mark_pause() to so that the pause does
807 // the initial-mark work and start a marking cycle.
808 void decide_on_conc_mark_initiation();
809
810 // If an expansion would be appropriate, because recent GC overhead had
811 // exceeded the desired limit, return an amount to expand by.
812 virtual size_t expansion_amount();
813
814 // Print tracing information.
815 void print_tracing_info() const;
816
817 // Print stats on young survival ratio
818 void print_yg_surv_rate_info() const;
819
820 void finished_recalculating_age_indexes(bool is_survivors) {
821 if (is_survivors) {
822 _survivor_surv_rate_group->finished_recalculating_age_indexes();
823 } else {
824 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
825 }
826 // do that for any other surv rate groups
827 }
828
829 size_t young_list_target_length() const { return _young_list_target_length; }
830
831 bool is_young_list_full();
832
833 bool can_expand_young_list();
834
835 uint young_list_max_length() {
836 return _young_list_max_length;
837 }
838
839 bool gcs_are_young() {
840 return _gcs_are_young;
841 }
842 void set_gcs_are_young(bool gcs_are_young) {
843 _gcs_are_young = gcs_are_young;
844 }
845
846 bool adaptive_young_list_length() {
847 return _young_gen_sizer->adaptive_young_list_length();
848 }
849
850 private:
851 //
852 // Survivor regions policy.
853 //
854
855 // Current tenuring threshold, set to 0 if the collector reaches the
856 // maximum amount of survivors regions.
857 uint _tenuring_threshold;
858
859 // The limit on the number of regions allocated for survivors.
860 uint _max_survivor_regions;
861
862 // For reporting purposes.
863 // The value of _heap_bytes_before_gc is also used to calculate
864 // the cost of copying.
865
866 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC
867 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC
868 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC
869 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC
870
871 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC
872 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC
873
874 // The amount of survivor regions after a collection.
875 uint _recorded_survivor_regions;
876 // List of survivor regions.
877 HeapRegion* _recorded_survivor_head;
878 HeapRegion* _recorded_survivor_tail;
879
880 ageTable _survivors_age_table;
881
882 public:
883 uint tenuring_threshold() const { return _tenuring_threshold; }
884
885 static const uint REGIONS_UNLIMITED = (uint) -1;
886
887 uint max_regions(InCSetState dest) {
888 switch (dest.value()) {
889 case InCSetState::Young:
890 return _max_survivor_regions;
891 case InCSetState::Old:
892 return REGIONS_UNLIMITED;
893 default:
894 assert(false, err_msg("Unknown dest state: " CSETSTATE_FORMAT, dest.value()));
895 break;
896 }
897 // keep some compilers happy
898 return 0;
899 }
900
901 void note_start_adding_survivor_regions() {
902 _survivor_surv_rate_group->start_adding_regions();
903 }
904
905 void note_stop_adding_survivor_regions() {
906 _survivor_surv_rate_group->stop_adding_regions();
907 }
908
909 void record_survivor_regions(uint regions,
910 HeapRegion* head,
911 HeapRegion* tail) {
912 _recorded_survivor_regions = regions;
913 _recorded_survivor_head = head;
914 _recorded_survivor_tail = tail;
915 }
916
917 uint recorded_survivor_regions() {
918 return _recorded_survivor_regions;
919 }
920
921 void record_thread_age_table(ageTable* age_table) {
922 _survivors_age_table.merge_par(age_table);
923 }
924
925 void update_max_gc_locker_expansion();
926
927 // Calculates survivor space parameters.
928 void update_survivors_policy();
929
930 virtual void post_heap_initialize();
931 };
932
933 // This should move to some place more general...
934
935 // If we have "n" measurements, and we've kept track of their "sum" and the
936 // "sum_of_squares" of the measurements, this returns the variance of the
937 // sequence.
938 inline double variance(int n, double sum_of_squares, double sum) {
939 double n_d = (double)n;
940 double avg = sum/n_d;
941 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
942 }
943
944 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP