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_init_times_ms;
145 TruncatedSeq* _concurrent_mark_remark_times_ms;
146 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
147
148 Summary* _summary;
149
150 NumberSeq* _all_pause_times_ms;
151 NumberSeq* _all_full_gc_times_ms;
152 double _stop_world_start;
153 NumberSeq* _all_stop_world_times_ms;
154 NumberSeq* _all_yield_times_ms;
155
156 size_t _region_num_young;
157 size_t _region_num_tenured;
158 size_t _prev_region_num_young;
159 size_t _prev_region_num_tenured;
160
161 NumberSeq* _all_mod_union_times_ms;
162
163 int _aux_num;
164 NumberSeq* _all_aux_times_ms;
165 double* _cur_aux_start_times_ms;
166 double* _cur_aux_times_ms;
167 bool* _cur_aux_times_set;
168
169 double* _par_last_gc_worker_start_times_ms;
170 double* _par_last_ext_root_scan_times_ms;
171 double* _par_last_mark_stack_scan_times_ms;
172 double* _par_last_update_rs_times_ms;
173 double* _par_last_update_rs_processed_buffers;
174 double* _par_last_scan_rs_times_ms;
175 double* _par_last_obj_copy_times_ms;
176 double* _par_last_termination_times_ms;
177 double* _par_last_termination_attempts;
178 double* _par_last_gc_worker_end_times_ms;
179 double* _par_last_gc_worker_times_ms;
180
181 // indicates that we are in young GC mode
182 bool _in_young_gc_mode;
183
184 // indicates whether we are in full young or partially young GC mode
185 bool _full_young_gcs;
186
187 // if true, then it tries to dynamically adjust the length of the
188 // young list
189 bool _adaptive_young_list_length;
190 size_t _young_list_min_length;
191 size_t _young_list_target_length;
192 size_t _young_list_fixed_length;
193
194 // The max number of regions we can extend the eden by while the GC
195 // locker is active. This should be >= _young_list_target_length;
196 size_t _young_list_max_length;
197
198 size_t _young_cset_length;
199 bool _last_young_gc_full;
200
201 unsigned _full_young_pause_num;
202 unsigned _partial_young_pause_num;
203
204 bool _during_marking;
205 bool _in_marking_window;
206 bool _in_marking_window_im;
207
208 SurvRateGroup* _short_lived_surv_rate_group;
209 SurvRateGroup* _survivor_surv_rate_group;
210 // add here any more surv rate groups
211
212 double _gc_overhead_perc;
213
214 bool during_marking() {
215 return _during_marking;
216 }
217
218 // <NEW PREDICTION>
219
220 private:
221 enum PredictionConstants {
222 TruncatedSeqLength = 10
223 };
224
225 TruncatedSeq* _alloc_rate_ms_seq;
226 double _prev_collection_pause_end_ms;
227
228 TruncatedSeq* _pending_card_diff_seq;
229 TruncatedSeq* _rs_length_diff_seq;
230 TruncatedSeq* _cost_per_card_ms_seq;
231 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
232 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
233 TruncatedSeq* _cost_per_entry_ms_seq;
234 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
235 TruncatedSeq* _cost_per_byte_ms_seq;
236 TruncatedSeq* _constant_other_time_ms_seq;
237 TruncatedSeq* _young_other_cost_per_region_ms_seq;
238 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
239
240 TruncatedSeq* _pending_cards_seq;
241 TruncatedSeq* _scanned_cards_seq;
242 TruncatedSeq* _rs_lengths_seq;
243
244 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
245
246 TruncatedSeq* _young_gc_eff_seq;
247
248 TruncatedSeq* _max_conc_overhead_seq;
249
250 size_t _recorded_young_regions;
251 size_t _recorded_non_young_regions;
252 size_t _recorded_region_num;
253
254 size_t _free_regions_at_end_of_collection;
255
256 size_t _recorded_rs_lengths;
257 size_t _max_rs_lengths;
258
259 size_t _recorded_marked_bytes;
260 size_t _recorded_young_bytes;
261
262 size_t _predicted_pending_cards;
263 size_t _predicted_cards_scanned;
264 size_t _predicted_rs_lengths;
265 size_t _predicted_bytes_to_copy;
266
267 double _predicted_survival_ratio;
268 double _predicted_rs_update_time_ms;
269 double _predicted_rs_scan_time_ms;
270 double _predicted_object_copy_time_ms;
271 double _predicted_constant_other_time_ms;
272 double _predicted_young_other_time_ms;
273 double _predicted_non_young_other_time_ms;
274 double _predicted_pause_time_ms;
275
276 double _vtime_diff_ms;
277
278 double _recorded_young_free_cset_time_ms;
279 double _recorded_non_young_free_cset_time_ms;
280
281 double _sigma;
282 double _expensive_region_limit_ms;
283
284 size_t _rs_lengths_prediction;
285
286 size_t _known_garbage_bytes;
287 double _known_garbage_ratio;
288
289 double sigma() {
290 return _sigma;
291 }
292
293 // A function that prevents us putting too much stock in small sample
294 // sets. Returns a number between 2.0 and 1.0, depending on the number
295 // of samples. 5 or more samples yields one; fewer scales linearly from
296 // 2.0 at 1 sample to 1.0 at 5.
297 double confidence_factor(int samples) {
298 if (samples > 4) return 1.0;
299 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
300 }
301
302 double get_new_neg_prediction(TruncatedSeq* seq) {
303 return seq->davg() - sigma() * seq->dsd();
304 }
305
306 #ifndef PRODUCT
307 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
308 #endif // PRODUCT
309
310 void adjust_concurrent_refinement(double update_rs_time,
311 double update_rs_processed_buffers,
312 double goal_ms);
313
314 protected:
315 double _pause_time_target_ms;
316 double _recorded_young_cset_choice_time_ms;
317 double _recorded_non_young_cset_choice_time_ms;
318 bool _within_target;
319 size_t _pending_cards;
320 size_t _max_pending_cards;
321
322 public:
323
324 void set_region_short_lived(HeapRegion* hr) {
325 hr->install_surv_rate_group(_short_lived_surv_rate_group);
326 }
327
328 void set_region_survivors(HeapRegion* hr) {
329 hr->install_surv_rate_group(_survivor_surv_rate_group);
330 }
331
332 #ifndef PRODUCT
333 bool verify_young_ages();
334 #endif // PRODUCT
335
336 double get_new_prediction(TruncatedSeq* seq) {
337 return MAX2(seq->davg() + sigma() * seq->dsd(),
338 seq->davg() * confidence_factor(seq->num()));
339 }
340
341 size_t young_cset_length() {
342 return _young_cset_length;
343 }
344
345 void record_max_rs_lengths(size_t rs_lengths) {
346 _max_rs_lengths = rs_lengths;
347 }
348
349 size_t predict_pending_card_diff() {
350 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
351 if (prediction < 0.00001)
352 return 0;
353 else
354 return (size_t) prediction;
355 }
356
357 size_t predict_pending_cards() {
358 size_t max_pending_card_num = _g1->max_pending_card_num();
359 size_t diff = predict_pending_card_diff();
360 size_t prediction;
361 if (diff > max_pending_card_num)
362 prediction = max_pending_card_num;
363 else
364 prediction = max_pending_card_num - diff;
365
366 return prediction;
367 }
368
369 size_t predict_rs_length_diff() {
370 return (size_t) get_new_prediction(_rs_length_diff_seq);
371 }
372
373 double predict_alloc_rate_ms() {
374 return get_new_prediction(_alloc_rate_ms_seq);
375 }
376
377 double predict_cost_per_card_ms() {
378 return get_new_prediction(_cost_per_card_ms_seq);
379 }
380
381 double predict_rs_update_time_ms(size_t pending_cards) {
382 return (double) pending_cards * predict_cost_per_card_ms();
383 }
384
385 double predict_fully_young_cards_per_entry_ratio() {
386 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
387 }
388
389 double predict_partially_young_cards_per_entry_ratio() {
390 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
391 return predict_fully_young_cards_per_entry_ratio();
392 else
393 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
394 }
395
396 size_t predict_young_card_num(size_t rs_length) {
397 return (size_t) ((double) rs_length *
398 predict_fully_young_cards_per_entry_ratio());
399 }
400
401 size_t predict_non_young_card_num(size_t rs_length) {
402 return (size_t) ((double) rs_length *
403 predict_partially_young_cards_per_entry_ratio());
404 }
405
406 double predict_rs_scan_time_ms(size_t card_num) {
407 if (full_young_gcs())
408 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
409 else
410 return predict_partially_young_rs_scan_time_ms(card_num);
411 }
412
413 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
414 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
415 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
416 else
417 return (double) card_num *
418 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
419 }
420
421 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
422 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
423 return 1.1 * (double) bytes_to_copy *
424 get_new_prediction(_cost_per_byte_ms_seq);
425 else
426 return (double) bytes_to_copy *
427 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
428 }
429
430 double predict_object_copy_time_ms(size_t bytes_to_copy) {
431 if (_in_marking_window && !_in_marking_window_im)
432 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
433 else
434 return (double) bytes_to_copy *
435 get_new_prediction(_cost_per_byte_ms_seq);
436 }
437
438 double predict_constant_other_time_ms() {
439 return get_new_prediction(_constant_other_time_ms_seq);
440 }
441
442 double predict_young_other_time_ms(size_t young_num) {
443 return
444 (double) young_num *
445 get_new_prediction(_young_other_cost_per_region_ms_seq);
446 }
447
448 double predict_non_young_other_time_ms(size_t non_young_num) {
449 return
450 (double) non_young_num *
451 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
452 }
453
454 void check_if_region_is_too_expensive(double predicted_time_ms);
455
456 double predict_young_collection_elapsed_time_ms(size_t adjustment);
457 double predict_base_elapsed_time_ms(size_t pending_cards);
458 double predict_base_elapsed_time_ms(size_t pending_cards,
459 size_t scanned_cards);
460 size_t predict_bytes_to_copy(HeapRegion* hr);
461 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
462
463 // for use by: calculate_young_list_target_length(rs_length)
464 bool predict_will_fit(size_t young_region_num,
465 double base_time_ms,
466 size_t init_free_regions,
467 double target_pause_time_ms);
468
469 void start_recording_regions();
470 void record_cset_region_info(HeapRegion* hr, bool young);
471 void record_non_young_cset_region(HeapRegion* hr);
472
473 void set_recorded_young_regions(size_t n_regions);
474 void set_recorded_young_bytes(size_t bytes);
475 void set_recorded_rs_lengths(size_t rs_lengths);
476 void set_predicted_bytes_to_copy(size_t bytes);
477
478 void end_recording_regions();
479
480 void record_vtime_diff_ms(double vtime_diff_ms) {
481 _vtime_diff_ms = vtime_diff_ms;
482 }
483
484 void record_young_free_cset_time_ms(double time_ms) {
485 _recorded_young_free_cset_time_ms = time_ms;
486 }
487
488 void record_non_young_free_cset_time_ms(double time_ms) {
489 _recorded_non_young_free_cset_time_ms = time_ms;
490 }
491
492 double predict_young_gc_eff() {
493 return get_new_neg_prediction(_young_gc_eff_seq);
494 }
495
496 double predict_survivor_regions_evac_time();
497
498 // </NEW PREDICTION>
499
500 public:
501 void cset_regions_freed() {
502 bool propagate = _last_young_gc_full && !_in_marking_window;
503 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
504 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
505 // also call it on any more surv rate groups
506 }
507
508 void set_known_garbage_bytes(size_t known_garbage_bytes) {
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 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
515 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
516
517 _known_garbage_bytes -= known_garbage_bytes;
518 size_t heap_bytes = _g1->capacity();
519 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
520 }
521
522 G1MMUTracker* mmu_tracker() {
523 return _mmu_tracker;
524 }
525
526 double max_pause_time_ms() {
527 return _mmu_tracker->max_gc_time() * 1000.0;
528 }
529
530 double predict_init_time_ms() {
531 return get_new_prediction(_concurrent_mark_init_times_ms);
532 }
533
534 double predict_remark_time_ms() {
535 return get_new_prediction(_concurrent_mark_remark_times_ms);
536 }
537
538 double predict_cleanup_time_ms() {
539 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
540 }
541
542 // Returns an estimate of the survival rate of the region at yg-age
543 // "yg_age".
544 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
545 TruncatedSeq* seq = surv_rate_group->get_seq(age);
546 if (seq->num() == 0)
547 gclog_or_tty->print("BARF! age is %d", age);
548 guarantee( seq->num() > 0, "invariant" );
549 double pred = get_new_prediction(seq);
550 if (pred > 1.0)
551 pred = 1.0;
552 return pred;
553 }
554
555 double predict_yg_surv_rate(int age) {
556 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
557 }
558
559 double accum_yg_surv_rate_pred(int age) {
560 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
561 }
562
563 protected:
564 void print_stats(int level, const char* str, double value);
565 void print_stats(int level, const char* str, int value);
566
567 void print_par_stats(int level, const char* str, double* data);
568 void print_par_sizes(int level, const char* str, double* data);
569
570 void check_other_times(int level,
571 NumberSeq* other_times_ms,
572 NumberSeq* calc_other_times_ms) const;
573
574 void print_summary (PauseSummary* stats) const;
575
576 void print_summary (int level, const char* str, NumberSeq* seq) const;
577 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
578
579 double avg_value (double* data);
580 double max_value (double* data);
581 double sum_of_values (double* data);
582 double max_sum (double* data1, double* data2);
583
584 int _last_satb_drain_processed_buffers;
585 int _last_update_rs_processed_buffers;
586 double _last_pause_time_ms;
587
588 size_t _bytes_in_collection_set_before_gc;
589 size_t _bytes_copied_during_gc;
590
591 // Used to count used bytes in CS.
592 friend class CountCSClosure;
593
594 // Statistics kept per GC stoppage, pause or full.
595 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
596
597 // We track markings.
598 int _num_markings;
599 double _mark_thread_startup_sec; // Time at startup of marking thread
600
601 // Add a new GC of the given duration and end time to the record.
602 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
603
604 // The head of the list (via "next_in_collection_set()") representing the
605 // current collection set. Set from the incrementally built collection
606 // set at the start of the pause.
607 HeapRegion* _collection_set;
608
609 // The number of regions in the collection set. Set from the incrementally
610 // built collection set at the start of an evacuation pause.
611 size_t _collection_set_size;
612
613 // The number of bytes in the collection set before the pause. Set from
614 // the incrementally built collection set at the start of an evacuation
615 // pause.
616 size_t _collection_set_bytes_used_before;
617
618 // The associated information that is maintained while the incremental
619 // collection set is being built with young regions. Used to populate
620 // the recorded info for the evacuation pause.
621
622 enum CSetBuildType {
623 Active, // We are actively building the collection set
624 Inactive // We are not actively building the collection set
625 };
626
627 CSetBuildType _inc_cset_build_state;
628
629 // The head of the incrementally built collection set.
630 HeapRegion* _inc_cset_head;
631
632 // The tail of the incrementally built collection set.
633 HeapRegion* _inc_cset_tail;
634
635 // The number of regions in the incrementally built collection set.
636 // Used to set _collection_set_size at the start of an evacuation
637 // pause.
638 size_t _inc_cset_size;
639
640 // Used as the index in the surving young words structure
641 // which tracks the amount of space, for each young region,
642 // that survives the pause.
643 size_t _inc_cset_young_index;
644
645 // The number of bytes in the incrementally built collection set.
646 // Used to set _collection_set_bytes_used_before at the start of
647 // an evacuation pause.
648 size_t _inc_cset_bytes_used_before;
649
650 // Used to record the highest end of heap region in collection set
651 HeapWord* _inc_cset_max_finger;
652
653 // The number of recorded used bytes in the young regions
654 // of the collection set. This is the sum of the used() bytes
655 // of retired young regions in the collection set.
656 size_t _inc_cset_recorded_young_bytes;
657
658 // The RSet lengths recorded for regions in the collection set
659 // (updated by the periodic sampling of the regions in the
660 // young list/collection set).
661 size_t _inc_cset_recorded_rs_lengths;
662
663 // The predicted elapsed time it will take to collect the regions
664 // in the collection set (updated by the periodic sampling of the
665 // regions in the young list/collection set).
666 double _inc_cset_predicted_elapsed_time_ms;
667
668 // The predicted bytes to copy for the regions in the collection
669 // set (updated by the periodic sampling of the regions in the
670 // young list/collection set).
671 size_t _inc_cset_predicted_bytes_to_copy;
672
673 // Info about marking.
674 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
675
676 // The number of collection pauses at the end of the last mark.
677 size_t _n_pauses_at_mark_end;
678
679 // Stash a pointer to the g1 heap.
680 G1CollectedHeap* _g1;
681
682 // The average time in ms per collection pause, averaged over recent pauses.
683 double recent_avg_time_for_pauses_ms();
684
685 // The average time in ms for RS scanning, per pause, averaged
686 // over recent pauses. (Note the RS scanning time for a pause
687 // is itself an average of the RS scanning time for each worker
688 // thread.)
689 double recent_avg_time_for_rs_scan_ms();
690
691 // The number of "recent" GCs recorded in the number sequences
692 int number_of_recent_gcs();
693
694 // The average survival ratio, computed by the total number of bytes
695 // suriviving / total number of bytes before collection over the last
696 // several recent pauses.
697 double recent_avg_survival_fraction();
698 // The survival fraction of the most recent pause; if there have been no
699 // pauses, returns 1.0.
700 double last_survival_fraction();
701
702 // Returns a "conservative" estimate of the recent survival rate, i.e.,
703 // one that may be higher than "recent_avg_survival_fraction".
704 // This is conservative in several ways:
705 // If there have been few pauses, it will assume a potential high
706 // variance, and err on the side of caution.
707 // It puts a lower bound (currently 0.1) on the value it will return.
708 // To try to detect phase changes, if the most recent pause ("latest") has a
709 // higher-than average ("avg") survival rate, it returns that rate.
710 // "work" version is a utility function; young is restricted to young regions.
711 double conservative_avg_survival_fraction_work(double avg,
712 double latest);
713
714 // The arguments are the two sequences that keep track of the number of bytes
715 // surviving and the total number of bytes before collection, resp.,
716 // over the last evereal recent pauses
717 // Returns the survival rate for the category in the most recent pause.
718 // If there have been no pauses, returns 1.0.
719 double last_survival_fraction_work(TruncatedSeq* surviving,
720 TruncatedSeq* before);
721
722 // The arguments are the two sequences that keep track of the number of bytes
723 // surviving and the total number of bytes before collection, resp.,
724 // over the last several recent pauses
725 // Returns the average survival ration over the last several recent pauses
726 // If there have been no pauses, return 1.0
727 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
728 TruncatedSeq* before);
729
730 double conservative_avg_survival_fraction() {
731 double avg = recent_avg_survival_fraction();
732 double latest = last_survival_fraction();
733 return conservative_avg_survival_fraction_work(avg, latest);
734 }
735
736 // The ratio of gc time to elapsed time, computed over recent pauses.
737 double _recent_avg_pause_time_ratio;
738
739 double recent_avg_pause_time_ratio() {
740 return _recent_avg_pause_time_ratio;
741 }
742
743 // Number of pauses between concurrent marking.
744 size_t _pauses_btwn_concurrent_mark;
745
746 size_t _n_marks_since_last_pause;
747
748 // At the end of a pause we check the heap occupancy and we decide
749 // whether we will start a marking cycle during the next pause. If
750 // we decide that we want to do that, we will set this parameter to
751 // true. So, this parameter will stay true between the end of a
752 // pause and the beginning of a subsequent pause (not necessarily
753 // the next one, see the comments on the next field) when we decide
754 // that we will indeed start a marking cycle and do the initial-mark
755 // work.
756 volatile bool _initiate_conc_mark_if_possible;
757
758 // If initiate_conc_mark_if_possible() is set at the beginning of a
759 // pause, it is a suggestion that the pause should start a marking
760 // cycle by doing the initial-mark work. However, it is possible
761 // that the concurrent marking thread is still finishing up the
762 // previous marking cycle (e.g., clearing the next marking
763 // bitmap). If that is the case we cannot start a new cycle and
764 // we'll have to wait for the concurrent marking thread to finish
765 // what it is doing. In this case we will postpone the marking cycle
766 // initiation decision for the next pause. When we eventually decide
767 // to start a cycle, we will set _during_initial_mark_pause which
768 // will stay true until the end of the initial-mark pause and it's
769 // the condition that indicates that a pause is doing the
770 // initial-mark work.
771 volatile bool _during_initial_mark_pause;
772
773 bool _should_revert_to_full_young_gcs;
774 bool _last_full_young_gc;
775
776 // This set of variables tracks the collector efficiency, in order to
777 // determine whether we should initiate a new marking.
778 double _cur_mark_stop_world_time_ms;
779 double _mark_init_start_sec;
780 double _mark_remark_start_sec;
781 double _mark_cleanup_start_sec;
782 double _mark_closure_time_ms;
783
784 void calculate_young_list_min_length();
785 void calculate_young_list_target_length();
786 void calculate_young_list_target_length(size_t rs_lengths);
787
788 public:
789
790 G1CollectorPolicy();
791
792 virtual G1CollectorPolicy* as_g1_policy() { return this; }
793
794 virtual CollectorPolicy::Name kind() {
795 return CollectorPolicy::G1CollectorPolicyKind;
796 }
797
798 void check_prediction_validity();
799
800 size_t bytes_in_collection_set() {
801 return _bytes_in_collection_set_before_gc;
802 }
803
804 unsigned calc_gc_alloc_time_stamp() {
805 return _all_pause_times_ms->num() + 1;
806 }
807
808 protected:
809
810 // Count the number of bytes used in the CS.
811 void count_CS_bytes_used();
812
813 // Together these do the base cleanup-recording work. Subclasses might
814 // want to put something between them.
815 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
816 size_t max_live_bytes);
817 void record_concurrent_mark_cleanup_end_work2();
818
819 public:
820
821 virtual void init();
822
823 // Create jstat counters for the policy.
824 virtual void initialize_gc_policy_counters();
825
826 virtual HeapWord* mem_allocate_work(size_t size,
827 bool is_tlab,
828 bool* gc_overhead_limit_was_exceeded);
829
830 // This method controls how a collector handles one or more
831 // of its generations being fully allocated.
832 virtual HeapWord* satisfy_failed_allocation(size_t size,
833 bool is_tlab);
834
835 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
836
837 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
838
839 // The number of collection pauses so far.
840 long n_pauses() const { return _n_pauses; }
841
842 // Update the heuristic info to record a collection pause of the given
843 // start time, where the given number of bytes were used at the start.
844 // This may involve changing the desired size of a collection set.
845
846 virtual void record_stop_world_start();
847
848 virtual void record_collection_pause_start(double start_time_sec,
849 size_t start_used);
850
851 // Must currently be called while the world is stopped.
852 virtual void record_concurrent_mark_init_start();
853 virtual void record_concurrent_mark_init_end();
854 void record_concurrent_mark_init_end_pre(double
855 mark_init_elapsed_time_ms);
856
857 void record_mark_closure_time(double mark_closure_time_ms);
858
859 virtual void record_concurrent_mark_remark_start();
860 virtual void record_concurrent_mark_remark_end();
861
862 virtual void record_concurrent_mark_cleanup_start();
863 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
864 size_t max_live_bytes);
865 virtual void record_concurrent_mark_cleanup_completed();
866
867 virtual void record_concurrent_pause();
868 virtual void record_concurrent_pause_end();
869
870 virtual void record_collection_pause_end();
871 void print_heap_transition();
872
873 // Record the fact that a full collection occurred.
874 virtual void record_full_collection_start();
875 virtual void record_full_collection_end();
876
877 void record_gc_worker_start_time(int worker_i, double ms) {
878 _par_last_gc_worker_start_times_ms[worker_i] = ms;
879 }
880
881 void record_ext_root_scan_time(int worker_i, double ms) {
882 _par_last_ext_root_scan_times_ms[worker_i] = ms;
883 }
884
885 void record_mark_stack_scan_time(int worker_i, double ms) {
886 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
887 }
888
889 void record_satb_drain_time(double ms) {
890 _cur_satb_drain_time_ms = ms;
891 _satb_drain_time_set = true;
892 }
893
894 void record_satb_drain_processed_buffers (int processed_buffers) {
895 _last_satb_drain_processed_buffers = processed_buffers;
896 }
897
898 void record_mod_union_time(double ms) {
899 _all_mod_union_times_ms->add(ms);
900 }
901
902 void record_update_rs_time(int thread, double ms) {
903 _par_last_update_rs_times_ms[thread] = ms;
904 }
905
906 void record_update_rs_processed_buffers (int thread,
907 double processed_buffers) {
908 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
909 }
910
911 void record_scan_rs_time(int thread, double ms) {
912 _par_last_scan_rs_times_ms[thread] = ms;
913 }
914
915 void reset_obj_copy_time(int thread) {
916 _par_last_obj_copy_times_ms[thread] = 0.0;
917 }
918
919 void reset_obj_copy_time() {
920 reset_obj_copy_time(0);
921 }
922
923 void record_obj_copy_time(int thread, double ms) {
924 _par_last_obj_copy_times_ms[thread] += ms;
925 }
926
927 void record_termination(int thread, double ms, size_t attempts) {
928 _par_last_termination_times_ms[thread] = ms;
929 _par_last_termination_attempts[thread] = (double) attempts;
930 }
931
932 void record_gc_worker_end_time(int worker_i, double ms) {
933 _par_last_gc_worker_end_times_ms[worker_i] = ms;
934 }
935
936 void record_pause_time_ms(double ms) {
937 _last_pause_time_ms = ms;
938 }
939
940 void record_clear_ct_time(double ms) {
941 _cur_clear_ct_time_ms = ms;
942 }
943
944 void record_par_time(double ms) {
945 _cur_collection_par_time_ms = ms;
946 }
947
948 void record_aux_start_time(int i) {
949 guarantee(i < _aux_num, "should be within range");
950 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
951 }
952
953 void record_aux_end_time(int i) {
954 guarantee(i < _aux_num, "should be within range");
955 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
956 _cur_aux_times_set[i] = true;
957 _cur_aux_times_ms[i] += ms;
958 }
959
960 #ifndef PRODUCT
961 void record_cc_clear_time(double ms) {
962 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
963 _min_clear_cc_time_ms = ms;
964 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
965 _max_clear_cc_time_ms = ms;
966 _cur_clear_cc_time_ms = ms;
967 _cum_clear_cc_time_ms += ms;
968 _num_cc_clears++;
969 }
970 #endif
971
972 // Record how much space we copied during a GC. This is typically
973 // called when a GC alloc region is being retired.
974 void record_bytes_copied_during_gc(size_t bytes) {
975 _bytes_copied_during_gc += bytes;
976 }
977
978 // The amount of space we copied during a GC.
979 size_t bytes_copied_during_gc() {
980 return _bytes_copied_during_gc;
981 }
982
983 // Choose a new collection set. Marks the chosen regions as being
984 // "in_collection_set", and links them together. The head and number of
985 // the collection set are available via access methods.
986 virtual void choose_collection_set(double target_pause_time_ms) = 0;
987
988 // The head of the list (via "next_in_collection_set()") representing the
989 // current collection set.
990 HeapRegion* collection_set() { return _collection_set; }
991
992 void clear_collection_set() { _collection_set = NULL; }
993
994 // The number of elements in the current collection set.
995 size_t collection_set_size() { return _collection_set_size; }
996
997 // Add "hr" to the CS.
998 void add_to_collection_set(HeapRegion* hr);
999
1000 // Incremental CSet Support
1001
1002 // The head of the incrementally built collection set.
1003 HeapRegion* inc_cset_head() { return _inc_cset_head; }
1004
1005 // The tail of the incrementally built collection set.
1006 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
1007
1008 // The number of elements in the incrementally built collection set.
1009 size_t inc_cset_size() { return _inc_cset_size; }
1010
1011 // Initialize incremental collection set info.
1012 void start_incremental_cset_building();
1013
1014 void clear_incremental_cset() {
1015 _inc_cset_head = NULL;
1016 _inc_cset_tail = NULL;
1017 }
1018
1019 // Stop adding regions to the incremental collection set
1020 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
1021
1022 // Add/remove information about hr to the aggregated information
1023 // for the incrementally built collection set.
1024 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
1025 void remove_from_incremental_cset_info(HeapRegion* hr);
1026
1027 // Update information about hr in the aggregated information for
1028 // the incrementally built collection set.
1029 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
1030
1031 private:
1032 // Update the incremental cset information when adding a region
1033 // (should not be called directly).
1034 void add_region_to_incremental_cset_common(HeapRegion* hr);
1035
1036 public:
1037 // Add hr to the LHS of the incremental collection set.
1038 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1039
1040 // Add hr to the RHS of the incremental collection set.
1041 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1042
1043 #ifndef PRODUCT
1044 void print_collection_set(HeapRegion* list_head, outputStream* st);
1045 #endif // !PRODUCT
1046
1047 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1048 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1049 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1050
1051 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1052 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1053 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1054
1055 // This sets the initiate_conc_mark_if_possible() flag to start a
1056 // new cycle, as long as we are not already in one. It's best if it
1057 // is called during a safepoint when the test whether a cycle is in
1058 // progress or not is stable.
1059 bool force_initial_mark_if_outside_cycle();
1060
1061 // This is called at the very beginning of an evacuation pause (it
1062 // has to be the first thing that the pause does). If
1063 // initiate_conc_mark_if_possible() is true, and the concurrent
1064 // marking thread has completed its work during the previous cycle,
1065 // it will set during_initial_mark_pause() to so that the pause does
1066 // the initial-mark work and start a marking cycle.
1067 void decide_on_conc_mark_initiation();
1068
1069 // If an expansion would be appropriate, because recent GC overhead had
1070 // exceeded the desired limit, return an amount to expand by.
1071 virtual size_t expansion_amount();
1072
1073 // note start of mark thread
1074 void note_start_of_mark_thread();
1075
1076 // The marked bytes of the "r" has changed; reclassify it's desirability
1077 // for marking. Also asserts that "r" is eligible for a CS.
1078 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
1079
1080 #ifndef PRODUCT
1081 // Check any appropriate marked bytes info, asserting false if
1082 // something's wrong, else returning "true".
1083 virtual bool assertMarkedBytesDataOK() = 0;
1084 #endif
1085
1086 // Print tracing information.
1087 void print_tracing_info() const;
1088
1089 // Print stats on young survival ratio
1090 void print_yg_surv_rate_info() const;
1091
1092 void finished_recalculating_age_indexes(bool is_survivors) {
1093 if (is_survivors) {
1094 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1095 } else {
1096 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1097 }
1098 // do that for any other surv rate groups
1099 }
1100
1101 bool is_young_list_full() {
1102 size_t young_list_length = _g1->young_list()->length();
1103 size_t young_list_target_length = _young_list_target_length;
1104 if (G1FixedEdenSize) {
1105 young_list_target_length -= _max_survivor_regions;
1106 }
1107 return young_list_length >= young_list_target_length;
1108 }
1109
1110 bool can_expand_young_list() {
1111 size_t young_list_length = _g1->young_list()->length();
1112 size_t young_list_max_length = _young_list_max_length;
1113 if (G1FixedEdenSize) {
1114 young_list_max_length -= _max_survivor_regions;
1115 }
1116 return young_list_length < young_list_max_length;
1117 }
1118
1119 void update_region_num(bool young);
1120
1121 bool in_young_gc_mode() {
1122 return _in_young_gc_mode;
1123 }
1124 void set_in_young_gc_mode(bool in_young_gc_mode) {
1125 _in_young_gc_mode = in_young_gc_mode;
1126 }
1127
1128 bool full_young_gcs() {
1129 return _full_young_gcs;
1130 }
1131 void set_full_young_gcs(bool full_young_gcs) {
1132 _full_young_gcs = full_young_gcs;
1133 }
1134
1135 bool adaptive_young_list_length() {
1136 return _adaptive_young_list_length;
1137 }
1138 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1139 _adaptive_young_list_length = adaptive_young_list_length;
1140 }
1141
1142 inline double get_gc_eff_factor() {
1143 double ratio = _known_garbage_ratio;
1144
1145 double square = ratio * ratio;
1146 // square = square * square;
1147 double ret = square * 9.0 + 1.0;
1148 #if 0
1149 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1150 #endif // 0
1151 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1152 return ret;
1153 }
1154
1155 //
1156 // Survivor regions policy.
1157 //
1158 protected:
1159
1160 // Current tenuring threshold, set to 0 if the collector reaches the
1161 // maximum amount of suvivors regions.
1162 int _tenuring_threshold;
1163
1164 // The limit on the number of regions allocated for survivors.
1165 size_t _max_survivor_regions;
1166
1167 // For reporting purposes.
1168 size_t _eden_bytes_before_gc;
1169 size_t _survivor_bytes_before_gc;
1170 size_t _capacity_before_gc;
1171
1172 // The amount of survor regions after a collection.
1173 size_t _recorded_survivor_regions;
1174 // List of survivor regions.
1175 HeapRegion* _recorded_survivor_head;
1176 HeapRegion* _recorded_survivor_tail;
1177
1178 ageTable _survivors_age_table;
1179
1180 public:
1181
1182 inline GCAllocPurpose
1183 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1184 if (age < _tenuring_threshold && src_region->is_young()) {
1185 return GCAllocForSurvived;
1186 } else {
1187 return GCAllocForTenured;
1188 }
1189 }
1190
1191 inline bool track_object_age(GCAllocPurpose purpose) {
1192 return purpose == GCAllocForSurvived;
1193 }
1194
1195 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1196
1197 size_t max_regions(int purpose);
1198
1199 // The limit on regions for a particular purpose is reached.
1200 void note_alloc_region_limit_reached(int purpose) {
1201 if (purpose == GCAllocForSurvived) {
1202 _tenuring_threshold = 0;
1203 }
1204 }
1205
1206 void note_start_adding_survivor_regions() {
1207 _survivor_surv_rate_group->start_adding_regions();
1208 }
1209
1210 void note_stop_adding_survivor_regions() {
1211 _survivor_surv_rate_group->stop_adding_regions();
1212 }
1213
1214 void record_survivor_regions(size_t regions,
1215 HeapRegion* head,
1216 HeapRegion* tail) {
1217 _recorded_survivor_regions = regions;
1218 _recorded_survivor_head = head;
1219 _recorded_survivor_tail = tail;
1220 }
1221
1222 size_t recorded_survivor_regions() {
1223 return _recorded_survivor_regions;
1224 }
1225
1226 void record_thread_age_table(ageTable* age_table)
1227 {
1228 _survivors_age_table.merge_par(age_table);
1229 }
1230
1231 void calculate_max_gc_locker_expansion();
1232
1233 // Calculates survivor space parameters.
1234 void calculate_survivors_policy();
1235
1236 };
1237
1238 // This encapsulates a particular strategy for a g1 Collector.
1239 //
1240 // Start a concurrent mark when our heap size is n bytes
1241 // greater then our heap size was at the last concurrent
1242 // mark. Where n is a function of the CMSTriggerRatio
1243 // and the MinHeapFreeRatio.
1244 //
1245 // Start a g1 collection pause when we have allocated the
1246 // average number of bytes currently being freed in
1247 // a collection, but only if it is at least one region
1248 // full
1249 //
1250 // Resize Heap based on desired
1251 // allocation space, where desired allocation space is
1252 // a function of survival rate and desired future to size.
1253 //
1254 // Choose collection set by first picking all older regions
1255 // which have a survival rate which beats our projected young
1256 // survival rate. Then fill out the number of needed regions
1257 // with young regions.
1258
1259 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1260 CollectionSetChooser* _collectionSetChooser;
1261 // If the estimated is less then desirable, resize if possible.
1262 void expand_if_possible(size_t numRegions);
1263
1264 virtual void choose_collection_set(double target_pause_time_ms);
1265 virtual void record_collection_pause_start(double start_time_sec,
1266 size_t start_used);
1267 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1268 size_t max_live_bytes);
1269 virtual void record_full_collection_end();
1270
1271 public:
1272 G1CollectorPolicy_BestRegionsFirst() {
1273 _collectionSetChooser = new CollectionSetChooser();
1274 }
1275 void record_collection_pause_end();
1276 // This is not needed any more, after the CSet choosing code was
1277 // changed to use the pause prediction work. But let's leave the
1278 // hook in just in case.
1279 void note_change_in_marked_bytes(HeapRegion* r) { }
1280 #ifndef PRODUCT
1281 bool assertMarkedBytesDataOK();
1282 #endif
1283 };
1284
1285 // This should move to some place more general...
1286
1287 // If we have "n" measurements, and we've kept track of their "sum" and the
1288 // "sum_of_squares" of the measurements, this returns the variance of the
1289 // sequence.
1290 inline double variance(int n, double sum_of_squares, double sum) {
1291 double n_d = (double)n;
1292 double avg = sum/n_d;
1293 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1294 }
1295
1296 // Local Variables: ***
1297 // c-indentation-style: gnu ***
1298 // End: ***
1299
1300 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP