1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
27
28 #include "gc_implementation/g1/collectionSetChooser.hpp"
29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 #include "memory/collectorPolicy.hpp"
31
32 // A G1CollectorPolicy makes policy decisions that determine the
33 // characteristics of the collector. Examples include:
34 // * choice of collection set.
35 // * when to collect.
36
37 class HeapRegion;
38 class CollectionSetChooser;
39
40 // Yes, this is a bit unpleasant... but it saves replicating the same thing
41 // over and over again and introducing subtle problems through small typos and
42 // cutting and pasting mistakes. The macros below introduces a number
43 // sequnce into the following two classes and the methods that access it.
44
45 #define define_num_seq(name) \
46 private: \
47 NumberSeq _all_##name##_times_ms; \
48 public: \
49 void record_##name##_time_ms(double ms) { \
50 _all_##name##_times_ms.add(ms); \
51 } \
52 NumberSeq* get_##name##_seq() { \
53 return &_all_##name##_times_ms; \
54 }
55
56 class MainBodySummary;
57
58 class PauseSummary: public CHeapObj {
59 define_num_seq(total)
60 define_num_seq(other)
61
62 public:
63 virtual MainBodySummary* main_body_summary() { return NULL; }
64 };
65
66 class MainBodySummary: public CHeapObj {
67 define_num_seq(satb_drain) // optional
68 define_num_seq(parallel) // parallel only
69 define_num_seq(ext_root_scan)
70 define_num_seq(mark_stack_scan)
71 define_num_seq(update_rs)
72 define_num_seq(scan_rs)
73 define_num_seq(obj_copy)
74 define_num_seq(termination) // parallel only
75 define_num_seq(parallel_other) // parallel only
76 define_num_seq(mark_closure)
77 define_num_seq(clear_ct) // parallel only
78 };
79
80 class Summary: public PauseSummary,
81 public MainBodySummary {
82 public:
83 virtual MainBodySummary* main_body_summary() { return this; }
84 };
85
86 class G1CollectorPolicy: public CollectorPolicy {
87 protected:
88 // The number of pauses during the execution.
89 long _n_pauses;
90
91 // either equal to the number of parallel threads, if ParallelGCThreads
92 // has been set, or 1 otherwise
93 int _parallel_gc_threads;
94
95 enum SomePrivateConstants {
96 NumPrevPausesForHeuristics = 10
97 };
98
99 G1MMUTracker* _mmu_tracker;
100
101 void initialize_flags();
102
103 void initialize_all() {
104 initialize_flags();
105 initialize_size_info();
106 initialize_perm_generation(PermGen::MarkSweepCompact);
107 }
108
109 virtual size_t default_init_heap_size() {
110 // Pick some reasonable default.
111 return 8*M;
112 }
113
114 double _cur_collection_start_sec;
115 size_t _cur_collection_pause_used_at_start_bytes;
116 size_t _cur_collection_pause_used_regions_at_start;
117 size_t _prev_collection_pause_used_at_end_bytes;
118 double _cur_collection_par_time_ms;
119 double _cur_satb_drain_time_ms;
120 double _cur_clear_ct_time_ms;
121 bool _satb_drain_time_set;
122
123 #ifndef PRODUCT
124 // Card Table Count Cache stats
125 double _min_clear_cc_time_ms; // min
126 double _max_clear_cc_time_ms; // max
127 double _cur_clear_cc_time_ms; // clearing time during current pause
128 double _cum_clear_cc_time_ms; // cummulative clearing time
129 jlong _num_cc_clears; // number of times the card count cache has been cleared
130 #endif
131
132 // Statistics for recent GC pauses. See below for how indexed.
133 TruncatedSeq* _recent_rs_scan_times_ms;
134
135 // These exclude marking times.
136 TruncatedSeq* _recent_pause_times_ms;
137 TruncatedSeq* _recent_gc_times_ms;
138
139 TruncatedSeq* _recent_CS_bytes_used_before;
140 TruncatedSeq* _recent_CS_bytes_surviving;
141
142 TruncatedSeq* _recent_rs_sizes;
143
144 TruncatedSeq* _concurrent_mark_remark_times_ms;
145 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
146
147 Summary* _summary;
148
149 NumberSeq* _all_pause_times_ms;
150 NumberSeq* _all_full_gc_times_ms;
151 double _stop_world_start;
152 NumberSeq* _all_stop_world_times_ms;
153 NumberSeq* _all_yield_times_ms;
154
155 size_t _region_num_young;
156 size_t _region_num_tenured;
157 size_t _prev_region_num_young;
158 size_t _prev_region_num_tenured;
159
160 NumberSeq* _all_mod_union_times_ms;
161
162 int _aux_num;
163 NumberSeq* _all_aux_times_ms;
164 double* _cur_aux_start_times_ms;
165 double* _cur_aux_times_ms;
166 bool* _cur_aux_times_set;
167
168 double* _par_last_gc_worker_start_times_ms;
169 double* _par_last_ext_root_scan_times_ms;
170 double* _par_last_mark_stack_scan_times_ms;
171 double* _par_last_update_rs_times_ms;
172 double* _par_last_update_rs_processed_buffers;
173 double* _par_last_scan_rs_times_ms;
174 double* _par_last_obj_copy_times_ms;
175 double* _par_last_termination_times_ms;
176 double* _par_last_termination_attempts;
177 double* _par_last_gc_worker_end_times_ms;
178 double* _par_last_gc_worker_times_ms;
179
180 // indicates whether we are in full young or partially young GC mode
181 bool _full_young_gcs;
182
183 // if true, then it tries to dynamically adjust the length of the
184 // young list
185 bool _adaptive_young_list_length;
186 size_t _young_list_target_length;
187 size_t _young_list_fixed_length;
188
189 // The max number of regions we can extend the eden by while the GC
190 // locker is active. This should be >= _young_list_target_length;
191 size_t _young_list_max_length;
192
193 size_t _young_cset_length;
194 bool _last_young_gc_full;
195
196 unsigned _full_young_pause_num;
197 unsigned _partial_young_pause_num;
198
199 bool _during_marking;
200 bool _in_marking_window;
201 bool _in_marking_window_im;
202
203 SurvRateGroup* _short_lived_surv_rate_group;
204 SurvRateGroup* _survivor_surv_rate_group;
205 // add here any more surv rate groups
206
207 double _gc_overhead_perc;
208
209 double _reserve_factor;
210 double _reserve_regions;
211
212 bool during_marking() {
213 return _during_marking;
214 }
215
216 // <NEW PREDICTION>
217
218 private:
219 enum PredictionConstants {
220 TruncatedSeqLength = 10
221 };
222
223 TruncatedSeq* _alloc_rate_ms_seq;
224 double _prev_collection_pause_end_ms;
225
226 TruncatedSeq* _pending_card_diff_seq;
227 TruncatedSeq* _rs_length_diff_seq;
228 TruncatedSeq* _cost_per_card_ms_seq;
229 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
230 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
231 TruncatedSeq* _cost_per_entry_ms_seq;
232 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
233 TruncatedSeq* _cost_per_byte_ms_seq;
234 TruncatedSeq* _constant_other_time_ms_seq;
235 TruncatedSeq* _young_other_cost_per_region_ms_seq;
236 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
237
238 TruncatedSeq* _pending_cards_seq;
239 TruncatedSeq* _scanned_cards_seq;
240 TruncatedSeq* _rs_lengths_seq;
241
242 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
243
244 TruncatedSeq* _young_gc_eff_seq;
245
246 TruncatedSeq* _max_conc_overhead_seq;
247
248 size_t _recorded_young_regions;
249 size_t _recorded_non_young_regions;
250 size_t _recorded_region_num;
251
252 size_t _free_regions_at_end_of_collection;
253
254 size_t _recorded_rs_lengths;
255 size_t _max_rs_lengths;
256
257 size_t _recorded_marked_bytes;
258 size_t _recorded_young_bytes;
259
260 size_t _predicted_pending_cards;
261 size_t _predicted_cards_scanned;
262 size_t _predicted_rs_lengths;
263 size_t _predicted_bytes_to_copy;
264
265 double _predicted_survival_ratio;
266 double _predicted_rs_update_time_ms;
267 double _predicted_rs_scan_time_ms;
268 double _predicted_object_copy_time_ms;
269 double _predicted_constant_other_time_ms;
270 double _predicted_young_other_time_ms;
271 double _predicted_non_young_other_time_ms;
272 double _predicted_pause_time_ms;
273
274 double _vtime_diff_ms;
275
276 double _recorded_young_free_cset_time_ms;
277 double _recorded_non_young_free_cset_time_ms;
278
279 double _sigma;
280 double _expensive_region_limit_ms;
281
282 size_t _rs_lengths_prediction;
283
284 size_t _known_garbage_bytes;
285 double _known_garbage_ratio;
286
287 double sigma() {
288 return _sigma;
289 }
290
291 // A function that prevents us putting too much stock in small sample
292 // sets. Returns a number between 2.0 and 1.0, depending on the number
293 // of samples. 5 or more samples yields one; fewer scales linearly from
294 // 2.0 at 1 sample to 1.0 at 5.
295 double confidence_factor(int samples) {
296 if (samples > 4) return 1.0;
297 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
298 }
299
300 double get_new_neg_prediction(TruncatedSeq* seq) {
301 return seq->davg() - sigma() * seq->dsd();
302 }
303
304 #ifndef PRODUCT
305 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
306 #endif // PRODUCT
307
308 void adjust_concurrent_refinement(double update_rs_time,
309 double update_rs_processed_buffers,
310 double goal_ms);
311
312 protected:
313 double _pause_time_target_ms;
314 double _recorded_young_cset_choice_time_ms;
315 double _recorded_non_young_cset_choice_time_ms;
316 bool _within_target;
317 size_t _pending_cards;
318 size_t _max_pending_cards;
319
320 public:
321
322 void set_region_short_lived(HeapRegion* hr) {
323 hr->install_surv_rate_group(_short_lived_surv_rate_group);
324 }
325
326 void set_region_survivors(HeapRegion* hr) {
327 hr->install_surv_rate_group(_survivor_surv_rate_group);
328 }
329
330 #ifndef PRODUCT
331 bool verify_young_ages();
332 #endif // PRODUCT
333
334 double get_new_prediction(TruncatedSeq* seq) {
335 return MAX2(seq->davg() + sigma() * seq->dsd(),
336 seq->davg() * confidence_factor(seq->num()));
337 }
338
339 size_t young_cset_length() {
340 return _young_cset_length;
341 }
342
343 void record_max_rs_lengths(size_t rs_lengths) {
344 _max_rs_lengths = rs_lengths;
345 }
346
347 size_t predict_pending_card_diff() {
348 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
349 if (prediction < 0.00001)
350 return 0;
351 else
352 return (size_t) prediction;
353 }
354
355 size_t predict_pending_cards() {
356 size_t max_pending_card_num = _g1->max_pending_card_num();
357 size_t diff = predict_pending_card_diff();
358 size_t prediction;
359 if (diff > max_pending_card_num)
360 prediction = max_pending_card_num;
361 else
362 prediction = max_pending_card_num - diff;
363
364 return prediction;
365 }
366
367 size_t predict_rs_length_diff() {
368 return (size_t) get_new_prediction(_rs_length_diff_seq);
369 }
370
371 double predict_alloc_rate_ms() {
372 return get_new_prediction(_alloc_rate_ms_seq);
373 }
374
375 double predict_cost_per_card_ms() {
376 return get_new_prediction(_cost_per_card_ms_seq);
377 }
378
379 double predict_rs_update_time_ms(size_t pending_cards) {
380 return (double) pending_cards * predict_cost_per_card_ms();
381 }
382
383 double predict_fully_young_cards_per_entry_ratio() {
384 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
385 }
386
387 double predict_partially_young_cards_per_entry_ratio() {
388 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
389 return predict_fully_young_cards_per_entry_ratio();
390 else
391 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
392 }
393
394 size_t predict_young_card_num(size_t rs_length) {
395 return (size_t) ((double) rs_length *
396 predict_fully_young_cards_per_entry_ratio());
397 }
398
399 size_t predict_non_young_card_num(size_t rs_length) {
400 return (size_t) ((double) rs_length *
401 predict_partially_young_cards_per_entry_ratio());
402 }
403
404 double predict_rs_scan_time_ms(size_t card_num) {
405 if (full_young_gcs())
406 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
407 else
408 return predict_partially_young_rs_scan_time_ms(card_num);
409 }
410
411 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
412 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
413 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
414 else
415 return (double) card_num *
416 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
417 }
418
419 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
420 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
421 return 1.1 * (double) bytes_to_copy *
422 get_new_prediction(_cost_per_byte_ms_seq);
423 else
424 return (double) bytes_to_copy *
425 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
426 }
427
428 double predict_object_copy_time_ms(size_t bytes_to_copy) {
429 if (_in_marking_window && !_in_marking_window_im)
430 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
431 else
432 return (double) bytes_to_copy *
433 get_new_prediction(_cost_per_byte_ms_seq);
434 }
435
436 double predict_constant_other_time_ms() {
437 return get_new_prediction(_constant_other_time_ms_seq);
438 }
439
440 double predict_young_other_time_ms(size_t young_num) {
441 return
442 (double) young_num *
443 get_new_prediction(_young_other_cost_per_region_ms_seq);
444 }
445
446 double predict_non_young_other_time_ms(size_t non_young_num) {
447 return
448 (double) non_young_num *
449 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
450 }
451
452 void check_if_region_is_too_expensive(double predicted_time_ms);
453
454 double predict_young_collection_elapsed_time_ms(size_t adjustment);
455 double predict_base_elapsed_time_ms(size_t pending_cards);
456 double predict_base_elapsed_time_ms(size_t pending_cards,
457 size_t scanned_cards);
458 size_t predict_bytes_to_copy(HeapRegion* hr);
459 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
460
461 void start_recording_regions();
462 void record_cset_region_info(HeapRegion* hr, bool young);
463 void record_non_young_cset_region(HeapRegion* hr);
464
465 void set_recorded_young_regions(size_t n_regions);
466 void set_recorded_young_bytes(size_t bytes);
467 void set_recorded_rs_lengths(size_t rs_lengths);
468 void set_predicted_bytes_to_copy(size_t bytes);
469
470 void end_recording_regions();
471
472 void record_vtime_diff_ms(double vtime_diff_ms) {
473 _vtime_diff_ms = vtime_diff_ms;
474 }
475
476 void record_young_free_cset_time_ms(double time_ms) {
477 _recorded_young_free_cset_time_ms = time_ms;
478 }
479
480 void record_non_young_free_cset_time_ms(double time_ms) {
481 _recorded_non_young_free_cset_time_ms = time_ms;
482 }
483
484 double predict_young_gc_eff() {
485 return get_new_neg_prediction(_young_gc_eff_seq);
486 }
487
488 double predict_survivor_regions_evac_time();
489
490 // </NEW PREDICTION>
491
492 public:
493 void cset_regions_freed() {
494 bool propagate = _last_young_gc_full && !_in_marking_window;
495 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
496 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
497 // also call it on any more surv rate groups
498 }
499
500 void set_known_garbage_bytes(size_t known_garbage_bytes) {
501 _known_garbage_bytes = known_garbage_bytes;
502 size_t heap_bytes = _g1->capacity();
503 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
504 }
505
506 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
507 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
508
509 _known_garbage_bytes -= known_garbage_bytes;
510 size_t heap_bytes = _g1->capacity();
511 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
512 }
513
514 G1MMUTracker* mmu_tracker() {
515 return _mmu_tracker;
516 }
517
518 double max_pause_time_ms() {
519 return _mmu_tracker->max_gc_time() * 1000.0;
520 }
521
522 double predict_remark_time_ms() {
523 return get_new_prediction(_concurrent_mark_remark_times_ms);
524 }
525
526 double predict_cleanup_time_ms() {
527 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
528 }
529
530 // Returns an estimate of the survival rate of the region at yg-age
531 // "yg_age".
532 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
533 TruncatedSeq* seq = surv_rate_group->get_seq(age);
534 if (seq->num() == 0)
535 gclog_or_tty->print("BARF! age is %d", age);
536 guarantee( seq->num() > 0, "invariant" );
537 double pred = get_new_prediction(seq);
538 if (pred > 1.0)
539 pred = 1.0;
540 return pred;
541 }
542
543 double predict_yg_surv_rate(int age) {
544 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
545 }
546
547 double accum_yg_surv_rate_pred(int age) {
548 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
549 }
550
551 protected:
552 void print_stats(int level, const char* str, double value);
553 void print_stats(int level, const char* str, int value);
554
555 void print_par_stats(int level, const char* str, double* data);
556 void print_par_sizes(int level, const char* str, double* data);
557
558 void check_other_times(int level,
559 NumberSeq* other_times_ms,
560 NumberSeq* calc_other_times_ms) const;
561
562 void print_summary (PauseSummary* stats) const;
563
564 void print_summary (int level, const char* str, NumberSeq* seq) const;
565 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
566
567 double avg_value (double* data);
568 double max_value (double* data);
569 double sum_of_values (double* data);
570 double max_sum (double* data1, double* data2);
571
572 int _last_satb_drain_processed_buffers;
573 int _last_update_rs_processed_buffers;
574 double _last_pause_time_ms;
575
576 size_t _bytes_in_collection_set_before_gc;
577 size_t _bytes_copied_during_gc;
578
579 // Used to count used bytes in CS.
580 friend class CountCSClosure;
581
582 // Statistics kept per GC stoppage, pause or full.
583 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
584
585 // We track markings.
586 int _num_markings;
587 double _mark_thread_startup_sec; // Time at startup of marking thread
588
589 // Add a new GC of the given duration and end time to the record.
590 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
591
592 // The head of the list (via "next_in_collection_set()") representing the
593 // current collection set. Set from the incrementally built collection
594 // set at the start of the pause.
595 HeapRegion* _collection_set;
596
597 // The number of regions in the collection set. Set from the incrementally
598 // built collection set at the start of an evacuation pause.
599 size_t _collection_set_size;
600
601 // The number of bytes in the collection set before the pause. Set from
602 // the incrementally built collection set at the start of an evacuation
603 // pause.
604 size_t _collection_set_bytes_used_before;
605
606 // The associated information that is maintained while the incremental
607 // collection set is being built with young regions. Used to populate
608 // the recorded info for the evacuation pause.
609
610 enum CSetBuildType {
611 Active, // We are actively building the collection set
612 Inactive // We are not actively building the collection set
613 };
614
615 CSetBuildType _inc_cset_build_state;
616
617 // The head of the incrementally built collection set.
618 HeapRegion* _inc_cset_head;
619
620 // The tail of the incrementally built collection set.
621 HeapRegion* _inc_cset_tail;
622
623 // The number of regions in the incrementally built collection set.
624 // Used to set _collection_set_size at the start of an evacuation
625 // pause.
626 size_t _inc_cset_size;
627
628 // Used as the index in the surving young words structure
629 // which tracks the amount of space, for each young region,
630 // that survives the pause.
631 size_t _inc_cset_young_index;
632
633 // The number of bytes in the incrementally built collection set.
634 // Used to set _collection_set_bytes_used_before at the start of
635 // an evacuation pause.
636 size_t _inc_cset_bytes_used_before;
637
638 // Used to record the highest end of heap region in collection set
639 HeapWord* _inc_cset_max_finger;
640
641 // The number of recorded used bytes in the young regions
642 // of the collection set. This is the sum of the used() bytes
643 // of retired young regions in the collection set.
644 size_t _inc_cset_recorded_young_bytes;
645
646 // The RSet lengths recorded for regions in the collection set
647 // (updated by the periodic sampling of the regions in the
648 // young list/collection set).
649 size_t _inc_cset_recorded_rs_lengths;
650
651 // The predicted elapsed time it will take to collect the regions
652 // in the collection set (updated by the periodic sampling of the
653 // regions in the young list/collection set).
654 double _inc_cset_predicted_elapsed_time_ms;
655
656 // The predicted bytes to copy for the regions in the collection
657 // set (updated by the periodic sampling of the regions in the
658 // young list/collection set).
659 size_t _inc_cset_predicted_bytes_to_copy;
660
661 // Info about marking.
662 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
663
664 // The number of collection pauses at the end of the last mark.
665 size_t _n_pauses_at_mark_end;
666
667 // Stash a pointer to the g1 heap.
668 G1CollectedHeap* _g1;
669
670 // The average time in ms per collection pause, averaged over recent pauses.
671 double recent_avg_time_for_pauses_ms();
672
673 // The average time in ms for RS scanning, per pause, averaged
674 // over recent pauses. (Note the RS scanning time for a pause
675 // is itself an average of the RS scanning time for each worker
676 // thread.)
677 double recent_avg_time_for_rs_scan_ms();
678
679 // The number of "recent" GCs recorded in the number sequences
680 int number_of_recent_gcs();
681
682 // The average survival ratio, computed by the total number of bytes
683 // suriviving / total number of bytes before collection over the last
684 // several recent pauses.
685 double recent_avg_survival_fraction();
686 // The survival fraction of the most recent pause; if there have been no
687 // pauses, returns 1.0.
688 double last_survival_fraction();
689
690 // Returns a "conservative" estimate of the recent survival rate, i.e.,
691 // one that may be higher than "recent_avg_survival_fraction".
692 // This is conservative in several ways:
693 // If there have been few pauses, it will assume a potential high
694 // variance, and err on the side of caution.
695 // It puts a lower bound (currently 0.1) on the value it will return.
696 // To try to detect phase changes, if the most recent pause ("latest") has a
697 // higher-than average ("avg") survival rate, it returns that rate.
698 // "work" version is a utility function; young is restricted to young regions.
699 double conservative_avg_survival_fraction_work(double avg,
700 double latest);
701
702 // The arguments are the two sequences that keep track of the number of bytes
703 // surviving and the total number of bytes before collection, resp.,
704 // over the last evereal recent pauses
705 // Returns the survival rate for the category in the most recent pause.
706 // If there have been no pauses, returns 1.0.
707 double last_survival_fraction_work(TruncatedSeq* surviving,
708 TruncatedSeq* before);
709
710 // The arguments are the two sequences that keep track of the number of bytes
711 // surviving and the total number of bytes before collection, resp.,
712 // over the last several recent pauses
713 // Returns the average survival ration over the last several recent pauses
714 // If there have been no pauses, return 1.0
715 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
716 TruncatedSeq* before);
717
718 double conservative_avg_survival_fraction() {
719 double avg = recent_avg_survival_fraction();
720 double latest = last_survival_fraction();
721 return conservative_avg_survival_fraction_work(avg, latest);
722 }
723
724 // The ratio of gc time to elapsed time, computed over recent pauses.
725 double _recent_avg_pause_time_ratio;
726
727 double recent_avg_pause_time_ratio() {
728 return _recent_avg_pause_time_ratio;
729 }
730
731 // Number of pauses between concurrent marking.
732 size_t _pauses_btwn_concurrent_mark;
733
734 size_t _n_marks_since_last_pause;
735
736 // At the end of a pause we check the heap occupancy and we decide
737 // whether we will start a marking cycle during the next pause. If
738 // we decide that we want to do that, we will set this parameter to
739 // true. So, this parameter will stay true between the end of a
740 // pause and the beginning of a subsequent pause (not necessarily
741 // the next one, see the comments on the next field) when we decide
742 // that we will indeed start a marking cycle and do the initial-mark
743 // work.
744 volatile bool _initiate_conc_mark_if_possible;
745
746 // If initiate_conc_mark_if_possible() is set at the beginning of a
747 // pause, it is a suggestion that the pause should start a marking
748 // cycle by doing the initial-mark work. However, it is possible
749 // that the concurrent marking thread is still finishing up the
750 // previous marking cycle (e.g., clearing the next marking
751 // bitmap). If that is the case we cannot start a new cycle and
752 // we'll have to wait for the concurrent marking thread to finish
753 // what it is doing. In this case we will postpone the marking cycle
754 // initiation decision for the next pause. When we eventually decide
755 // to start a cycle, we will set _during_initial_mark_pause which
756 // will stay true until the end of the initial-mark pause and it's
757 // the condition that indicates that a pause is doing the
758 // initial-mark work.
759 volatile bool _during_initial_mark_pause;
760
761 bool _should_revert_to_full_young_gcs;
762 bool _last_full_young_gc;
763
764 // This set of variables tracks the collector efficiency, in order to
765 // determine whether we should initiate a new marking.
766 double _cur_mark_stop_world_time_ms;
767 double _mark_remark_start_sec;
768 double _mark_cleanup_start_sec;
769 double _mark_closure_time_ms;
770
771 // Update the young list target length either by setting it to the
772 // desired fixed value or by calculating it using G1's pause
773 // prediction model. If no rs_lengths parameter is passed, predict
774 // the RS lengths using the prediction model, otherwise use the
775 // given rs_lengths as the prediction.
776 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
777
778 // Calculate and return the minimum desired young list target
779 // length. This is the minimum desired young list length according
780 // to the user's inputs.
781 size_t calculate_young_list_desired_min_length(size_t base_min_length);
782
783 // Calculate and return the maximum desired young list target
784 // length. This is the maximum desired young list length according
785 // to the user's inputs.
786 size_t calculate_young_list_desired_max_length();
787
788 // Calculate and return the maximum young list target length that
789 // can fit into the pause time goal. The parameters are: rs_lengths
790 // represent the prediction of how large the young RSet lengths will
791 // be, base_min_length is the alreay existing number of regions in
792 // the young list, min_length and max_length are the desired min and
793 // max young list length according to the user's inputs.
794 size_t calculate_young_list_target_length(size_t rs_lengths,
795 size_t base_min_length,
796 size_t desired_min_length,
797 size_t desired_max_length);
798
799 // Check whether a given young length (young_length) fits into the
800 // given target pause time and whether the prediction for the amount
801 // of objects to be copied for the given length will fit into the
802 // given free space (expressed by base_free_regions). It is used by
803 // calculate_young_list_target_length().
804 bool predict_will_fit(size_t young_length, double base_time_ms,
805 size_t base_free_regions, double target_pause_time_ms);
806
807 public:
808
809 G1CollectorPolicy();
810
811 virtual G1CollectorPolicy* as_g1_policy() { return this; }
812
813 virtual CollectorPolicy::Name kind() {
814 return CollectorPolicy::G1CollectorPolicyKind;
815 }
816
817 // Check the current value of the young list RSet lengths and
818 // compare it against the last prediction. If the current value is
819 // higher, recalculate the young list target length prediction.
820 void revise_young_list_target_length_if_necessary();
821
822 size_t bytes_in_collection_set() {
823 return _bytes_in_collection_set_before_gc;
824 }
825
826 unsigned calc_gc_alloc_time_stamp() {
827 return _all_pause_times_ms->num() + 1;
828 }
829
830 // Recalculate the reserve region number. This should be called
831 // after the heap is resized.
832 void calculate_reserve(size_t all_regions);
833
834 protected:
835
836 // Count the number of bytes used in the CS.
837 void count_CS_bytes_used();
838
839 // Together these do the base cleanup-recording work. Subclasses might
840 // want to put something between them.
841 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
842 size_t max_live_bytes);
843 void record_concurrent_mark_cleanup_end_work2();
844
845 public:
846
847 virtual void init();
848
849 // Create jstat counters for the policy.
850 virtual void initialize_gc_policy_counters();
851
852 virtual HeapWord* mem_allocate_work(size_t size,
853 bool is_tlab,
854 bool* gc_overhead_limit_was_exceeded);
855
856 // This method controls how a collector handles one or more
857 // of its generations being fully allocated.
858 virtual HeapWord* satisfy_failed_allocation(size_t size,
859 bool is_tlab);
860
861 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
862
863 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
864
865 // The number of collection pauses so far.
866 long n_pauses() const { return _n_pauses; }
867
868 // Update the heuristic info to record a collection pause of the given
869 // start time, where the given number of bytes were used at the start.
870 // This may involve changing the desired size of a collection set.
871
872 virtual void record_stop_world_start();
873
874 virtual void record_collection_pause_start(double start_time_sec,
875 size_t start_used);
876
877 // Must currently be called while the world is stopped.
878 void record_concurrent_mark_init_end(double
879 mark_init_elapsed_time_ms);
880
881 void record_mark_closure_time(double mark_closure_time_ms);
882
883 virtual void record_concurrent_mark_remark_start();
884 virtual void record_concurrent_mark_remark_end();
885
886 virtual void record_concurrent_mark_cleanup_start();
887 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
888 size_t max_live_bytes);
889 virtual void record_concurrent_mark_cleanup_completed();
890
891 virtual void record_concurrent_pause();
892 virtual void record_concurrent_pause_end();
893
894 virtual void record_collection_pause_end();
895 void print_heap_transition();
896
897 // Record the fact that a full collection occurred.
898 virtual void record_full_collection_start();
899 virtual void record_full_collection_end();
900
901 void record_gc_worker_start_time(int worker_i, double ms) {
902 _par_last_gc_worker_start_times_ms[worker_i] = ms;
903 }
904
905 void record_ext_root_scan_time(int worker_i, double ms) {
906 _par_last_ext_root_scan_times_ms[worker_i] = ms;
907 }
908
909 void record_mark_stack_scan_time(int worker_i, double ms) {
910 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
911 }
912
913 void record_satb_drain_time(double ms) {
914 _cur_satb_drain_time_ms = ms;
915 _satb_drain_time_set = true;
916 }
917
918 void record_satb_drain_processed_buffers (int processed_buffers) {
919 _last_satb_drain_processed_buffers = processed_buffers;
920 }
921
922 void record_mod_union_time(double ms) {
923 _all_mod_union_times_ms->add(ms);
924 }
925
926 void record_update_rs_time(int thread, double ms) {
927 _par_last_update_rs_times_ms[thread] = ms;
928 }
929
930 void record_update_rs_processed_buffers (int thread,
931 double processed_buffers) {
932 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
933 }
934
935 void record_scan_rs_time(int thread, double ms) {
936 _par_last_scan_rs_times_ms[thread] = ms;
937 }
938
939 void reset_obj_copy_time(int thread) {
940 _par_last_obj_copy_times_ms[thread] = 0.0;
941 }
942
943 void reset_obj_copy_time() {
944 reset_obj_copy_time(0);
945 }
946
947 void record_obj_copy_time(int thread, double ms) {
948 _par_last_obj_copy_times_ms[thread] += ms;
949 }
950
951 void record_termination(int thread, double ms, size_t attempts) {
952 _par_last_termination_times_ms[thread] = ms;
953 _par_last_termination_attempts[thread] = (double) attempts;
954 }
955
956 void record_gc_worker_end_time(int worker_i, double ms) {
957 _par_last_gc_worker_end_times_ms[worker_i] = ms;
958 }
959
960 void record_pause_time_ms(double ms) {
961 _last_pause_time_ms = ms;
962 }
963
964 void record_clear_ct_time(double ms) {
965 _cur_clear_ct_time_ms = ms;
966 }
967
968 void record_par_time(double ms) {
969 _cur_collection_par_time_ms = ms;
970 }
971
972 void record_aux_start_time(int i) {
973 guarantee(i < _aux_num, "should be within range");
974 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
975 }
976
977 void record_aux_end_time(int i) {
978 guarantee(i < _aux_num, "should be within range");
979 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
980 _cur_aux_times_set[i] = true;
981 _cur_aux_times_ms[i] += ms;
982 }
983
984 #ifndef PRODUCT
985 void record_cc_clear_time(double ms) {
986 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
987 _min_clear_cc_time_ms = ms;
988 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
989 _max_clear_cc_time_ms = ms;
990 _cur_clear_cc_time_ms = ms;
991 _cum_clear_cc_time_ms += ms;
992 _num_cc_clears++;
993 }
994 #endif
995
996 // Record how much space we copied during a GC. This is typically
997 // called when a GC alloc region is being retired.
998 void record_bytes_copied_during_gc(size_t bytes) {
999 _bytes_copied_during_gc += bytes;
1000 }
1001
1002 // The amount of space we copied during a GC.
1003 size_t bytes_copied_during_gc() {
1004 return _bytes_copied_during_gc;
1005 }
1006
1007 // Choose a new collection set. Marks the chosen regions as being
1008 // "in_collection_set", and links them together. The head and number of
1009 // the collection set are available via access methods.
1010 virtual void choose_collection_set(double target_pause_time_ms) = 0;
1011
1012 // The head of the list (via "next_in_collection_set()") representing the
1013 // current collection set.
1014 HeapRegion* collection_set() { return _collection_set; }
1015
1016 void clear_collection_set() { _collection_set = NULL; }
1017
1018 // The number of elements in the current collection set.
1019 size_t collection_set_size() { return _collection_set_size; }
1020
1021 // Add "hr" to the CS.
1022 void add_to_collection_set(HeapRegion* hr);
1023
1024 // Incremental CSet Support
1025
1026 // The head of the incrementally built collection set.
1027 HeapRegion* inc_cset_head() { return _inc_cset_head; }
1028
1029 // The tail of the incrementally built collection set.
1030 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
1031
1032 // The number of elements in the incrementally built collection set.
1033 size_t inc_cset_size() { return _inc_cset_size; }
1034
1035 // Initialize incremental collection set info.
1036 void start_incremental_cset_building();
1037
1038 void clear_incremental_cset() {
1039 _inc_cset_head = NULL;
1040 _inc_cset_tail = NULL;
1041 }
1042
1043 // Stop adding regions to the incremental collection set
1044 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
1045
1046 // Add/remove information about hr to the aggregated information
1047 // for the incrementally built collection set.
1048 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
1049 void remove_from_incremental_cset_info(HeapRegion* hr);
1050
1051 // Update information about hr in the aggregated information for
1052 // the incrementally built collection set.
1053 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
1054
1055 private:
1056 // Update the incremental cset information when adding a region
1057 // (should not be called directly).
1058 void add_region_to_incremental_cset_common(HeapRegion* hr);
1059
1060 public:
1061 // Add hr to the LHS of the incremental collection set.
1062 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1063
1064 // Add hr to the RHS of the incremental collection set.
1065 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1066
1067 #ifndef PRODUCT
1068 void print_collection_set(HeapRegion* list_head, outputStream* st);
1069 #endif // !PRODUCT
1070
1071 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1072 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1073 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1074
1075 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1076 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1077 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1078
1079 // This sets the initiate_conc_mark_if_possible() flag to start a
1080 // new cycle, as long as we are not already in one. It's best if it
1081 // is called during a safepoint when the test whether a cycle is in
1082 // progress or not is stable.
1083 bool force_initial_mark_if_outside_cycle();
1084
1085 // This is called at the very beginning of an evacuation pause (it
1086 // has to be the first thing that the pause does). If
1087 // initiate_conc_mark_if_possible() is true, and the concurrent
1088 // marking thread has completed its work during the previous cycle,
1089 // it will set during_initial_mark_pause() to so that the pause does
1090 // the initial-mark work and start a marking cycle.
1091 void decide_on_conc_mark_initiation();
1092
1093 // If an expansion would be appropriate, because recent GC overhead had
1094 // exceeded the desired limit, return an amount to expand by.
1095 virtual size_t expansion_amount();
1096
1097 // note start of mark thread
1098 void note_start_of_mark_thread();
1099
1100 // The marked bytes of the "r" has changed; reclassify it's desirability
1101 // for marking. Also asserts that "r" is eligible for a CS.
1102 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
1103
1104 #ifndef PRODUCT
1105 // Check any appropriate marked bytes info, asserting false if
1106 // something's wrong, else returning "true".
1107 virtual bool assertMarkedBytesDataOK() = 0;
1108 #endif
1109
1110 // Print tracing information.
1111 void print_tracing_info() const;
1112
1113 // Print stats on young survival ratio
1114 void print_yg_surv_rate_info() const;
1115
1116 void finished_recalculating_age_indexes(bool is_survivors) {
1117 if (is_survivors) {
1118 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1119 } else {
1120 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1121 }
1122 // do that for any other surv rate groups
1123 }
1124
1125 bool is_young_list_full() {
1126 size_t young_list_length = _g1->young_list()->length();
1127 size_t young_list_target_length = _young_list_target_length;
1128 return young_list_length >= young_list_target_length;
1129 }
1130
1131 bool can_expand_young_list() {
1132 size_t young_list_length = _g1->young_list()->length();
1133 size_t young_list_max_length = _young_list_max_length;
1134 return young_list_length < young_list_max_length;
1135 }
1136
1137 void update_region_num(bool young);
1138
1139 bool full_young_gcs() {
1140 return _full_young_gcs;
1141 }
1142 void set_full_young_gcs(bool full_young_gcs) {
1143 _full_young_gcs = full_young_gcs;
1144 }
1145
1146 bool adaptive_young_list_length() {
1147 return _adaptive_young_list_length;
1148 }
1149 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1150 _adaptive_young_list_length = adaptive_young_list_length;
1151 }
1152
1153 inline double get_gc_eff_factor() {
1154 double ratio = _known_garbage_ratio;
1155
1156 double square = ratio * ratio;
1157 // square = square * square;
1158 double ret = square * 9.0 + 1.0;
1159 #if 0
1160 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1161 #endif // 0
1162 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1163 return ret;
1164 }
1165
1166 //
1167 // Survivor regions policy.
1168 //
1169 protected:
1170
1171 // Current tenuring threshold, set to 0 if the collector reaches the
1172 // maximum amount of suvivors regions.
1173 int _tenuring_threshold;
1174
1175 // The limit on the number of regions allocated for survivors.
1176 size_t _max_survivor_regions;
1177
1178 // For reporting purposes.
1179 size_t _eden_bytes_before_gc;
1180 size_t _survivor_bytes_before_gc;
1181 size_t _capacity_before_gc;
1182
1183 // The amount of survor regions after a collection.
1184 size_t _recorded_survivor_regions;
1185 // List of survivor regions.
1186 HeapRegion* _recorded_survivor_head;
1187 HeapRegion* _recorded_survivor_tail;
1188
1189 ageTable _survivors_age_table;
1190
1191 public:
1192
1193 inline GCAllocPurpose
1194 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1195 if (age < _tenuring_threshold && src_region->is_young()) {
1196 return GCAllocForSurvived;
1197 } else {
1198 return GCAllocForTenured;
1199 }
1200 }
1201
1202 inline bool track_object_age(GCAllocPurpose purpose) {
1203 return purpose == GCAllocForSurvived;
1204 }
1205
1206 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1207
1208 size_t max_regions(int purpose);
1209
1210 // The limit on regions for a particular purpose is reached.
1211 void note_alloc_region_limit_reached(int purpose) {
1212 if (purpose == GCAllocForSurvived) {
1213 _tenuring_threshold = 0;
1214 }
1215 }
1216
1217 void note_start_adding_survivor_regions() {
1218 _survivor_surv_rate_group->start_adding_regions();
1219 }
1220
1221 void note_stop_adding_survivor_regions() {
1222 _survivor_surv_rate_group->stop_adding_regions();
1223 }
1224
1225 void record_survivor_regions(size_t regions,
1226 HeapRegion* head,
1227 HeapRegion* tail) {
1228 _recorded_survivor_regions = regions;
1229 _recorded_survivor_head = head;
1230 _recorded_survivor_tail = tail;
1231 }
1232
1233 size_t recorded_survivor_regions() {
1234 return _recorded_survivor_regions;
1235 }
1236
1237 void record_thread_age_table(ageTable* age_table)
1238 {
1239 _survivors_age_table.merge_par(age_table);
1240 }
1241
1242 void update_max_gc_locker_expansion();
1243
1244 // Calculates survivor space parameters.
1245 void update_survivors_policy();
1246
1247 };
1248
1249 // This encapsulates a particular strategy for a g1 Collector.
1250 //
1251 // Start a concurrent mark when our heap size is n bytes
1252 // greater then our heap size was at the last concurrent
1253 // mark. Where n is a function of the CMSTriggerRatio
1254 // and the MinHeapFreeRatio.
1255 //
1256 // Start a g1 collection pause when we have allocated the
1257 // average number of bytes currently being freed in
1258 // a collection, but only if it is at least one region
1259 // full
1260 //
1261 // Resize Heap based on desired
1262 // allocation space, where desired allocation space is
1263 // a function of survival rate and desired future to size.
1264 //
1265 // Choose collection set by first picking all older regions
1266 // which have a survival rate which beats our projected young
1267 // survival rate. Then fill out the number of needed regions
1268 // with young regions.
1269
1270 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1271 CollectionSetChooser* _collectionSetChooser;
1272 // If the estimated is less then desirable, resize if possible.
1273 void expand_if_possible(size_t numRegions);
1274
1275 virtual void choose_collection_set(double target_pause_time_ms);
1276 virtual void record_collection_pause_start(double start_time_sec,
1277 size_t start_used);
1278 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1279 size_t max_live_bytes);
1280 virtual void record_full_collection_end();
1281
1282 public:
1283 G1CollectorPolicy_BestRegionsFirst() {
1284 _collectionSetChooser = new CollectionSetChooser();
1285 }
1286 void record_collection_pause_end();
1287 // This is not needed any more, after the CSet choosing code was
1288 // changed to use the pause prediction work. But let's leave the
1289 // hook in just in case.
1290 void note_change_in_marked_bytes(HeapRegion* r) { }
1291 #ifndef PRODUCT
1292 bool assertMarkedBytesDataOK();
1293 #endif
1294 };
1295
1296 // This should move to some place more general...
1297
1298 // If we have "n" measurements, and we've kept track of their "sum" and the
1299 // "sum_of_squares" of the measurements, this returns the variance of the
1300 // sequence.
1301 inline double variance(int n, double sum_of_squares, double sum) {
1302 double n_d = (double)n;
1303 double avg = sum/n_d;
1304 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1305 }
1306
1307 // Local Variables: ***
1308 // c-indentation-style: gnu ***
1309 // End: ***
1310
1311 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP