1 /*
2 * Copyright (c) 2001, 2010, 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 double _cur_ref_proc_time_ms;
123 double _cur_ref_enq_time_ms;
124
125 #ifndef PRODUCT
126 // Card Table Count Cache stats
127 double _min_clear_cc_time_ms; // min
128 double _max_clear_cc_time_ms; // max
129 double _cur_clear_cc_time_ms; // clearing time during current pause
130 double _cum_clear_cc_time_ms; // cummulative clearing time
131 jlong _num_cc_clears; // number of times the card count cache has been cleared
132 #endif
133
134 // Statistics for recent GC pauses. See below for how indexed.
135 TruncatedSeq* _recent_rs_scan_times_ms;
136
137 // These exclude marking times.
138 TruncatedSeq* _recent_pause_times_ms;
139 TruncatedSeq* _recent_gc_times_ms;
140
141 TruncatedSeq* _recent_CS_bytes_used_before;
142 TruncatedSeq* _recent_CS_bytes_surviving;
143
144 TruncatedSeq* _recent_rs_sizes;
145
146 TruncatedSeq* _concurrent_mark_init_times_ms;
147 TruncatedSeq* _concurrent_mark_remark_times_ms;
148 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
149
150 Summary* _summary;
151
152 NumberSeq* _all_pause_times_ms;
153 NumberSeq* _all_full_gc_times_ms;
154 double _stop_world_start;
155 NumberSeq* _all_stop_world_times_ms;
156 NumberSeq* _all_yield_times_ms;
157
158 size_t _region_num_young;
159 size_t _region_num_tenured;
160 size_t _prev_region_num_young;
161 size_t _prev_region_num_tenured;
162
163 NumberSeq* _all_mod_union_times_ms;
164
165 int _aux_num;
166 NumberSeq* _all_aux_times_ms;
167 double* _cur_aux_start_times_ms;
168 double* _cur_aux_times_ms;
169 bool* _cur_aux_times_set;
170
171 double* _par_last_gc_worker_start_times_ms;
172 double* _par_last_ext_root_scan_times_ms;
173 double* _par_last_mark_stack_scan_times_ms;
174 double* _par_last_update_rs_times_ms;
175 double* _par_last_update_rs_processed_buffers;
176 double* _par_last_scan_rs_times_ms;
177 double* _par_last_obj_copy_times_ms;
178 double* _par_last_termination_times_ms;
179 double* _par_last_termination_attempts;
180 double* _par_last_gc_worker_end_times_ms;
181 double* _par_last_gc_worker_times_ms;
182
183 // indicates that we are in young GC mode
184 bool _in_young_gc_mode;
185
186 // indicates whether we are in full young or partially young GC mode
187 bool _full_young_gcs;
188
189 // if true, then it tries to dynamically adjust the length of the
190 // young list
191 bool _adaptive_young_list_length;
192 size_t _young_list_min_length;
193 size_t _young_list_target_length;
194 size_t _young_list_fixed_length;
195
196 // The max number of regions we can extend the eden by while the GC
197 // locker is active. This should be >= _young_list_target_length;
198 size_t _young_list_max_length;
199
200 size_t _young_cset_length;
201 bool _last_young_gc_full;
202
203 unsigned _full_young_pause_num;
204 unsigned _partial_young_pause_num;
205
206 bool _during_marking;
207 bool _in_marking_window;
208 bool _in_marking_window_im;
209
210 SurvRateGroup* _short_lived_surv_rate_group;
211 SurvRateGroup* _survivor_surv_rate_group;
212 // add here any more surv rate groups
213
214 double _gc_overhead_perc;
215
216 bool during_marking() {
217 return _during_marking;
218 }
219
220 // <NEW PREDICTION>
221
222 private:
223 enum PredictionConstants {
224 TruncatedSeqLength = 10
225 };
226
227 TruncatedSeq* _alloc_rate_ms_seq;
228 double _prev_collection_pause_end_ms;
229
230 TruncatedSeq* _pending_card_diff_seq;
231 TruncatedSeq* _rs_length_diff_seq;
232 TruncatedSeq* _cost_per_card_ms_seq;
233 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
234 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
235 TruncatedSeq* _cost_per_entry_ms_seq;
236 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
237 TruncatedSeq* _cost_per_byte_ms_seq;
238 TruncatedSeq* _constant_other_time_ms_seq;
239 TruncatedSeq* _young_other_cost_per_region_ms_seq;
240 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
241
242 TruncatedSeq* _pending_cards_seq;
243 TruncatedSeq* _scanned_cards_seq;
244 TruncatedSeq* _rs_lengths_seq;
245
246 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
247
248 TruncatedSeq* _young_gc_eff_seq;
249
250 TruncatedSeq* _max_conc_overhead_seq;
251
252 size_t _recorded_young_regions;
253 size_t _recorded_non_young_regions;
254 size_t _recorded_region_num;
255
256 size_t _free_regions_at_end_of_collection;
257
258 size_t _recorded_rs_lengths;
259 size_t _max_rs_lengths;
260
261 size_t _recorded_marked_bytes;
262 size_t _recorded_young_bytes;
263
264 size_t _predicted_pending_cards;
265 size_t _predicted_cards_scanned;
266 size_t _predicted_rs_lengths;
267 size_t _predicted_bytes_to_copy;
268
269 double _predicted_survival_ratio;
270 double _predicted_rs_update_time_ms;
271 double _predicted_rs_scan_time_ms;
272 double _predicted_object_copy_time_ms;
273 double _predicted_constant_other_time_ms;
274 double _predicted_young_other_time_ms;
275 double _predicted_non_young_other_time_ms;
276 double _predicted_pause_time_ms;
277
278 double _vtime_diff_ms;
279
280 double _recorded_young_free_cset_time_ms;
281 double _recorded_non_young_free_cset_time_ms;
282
283 double _sigma;
284 double _expensive_region_limit_ms;
285
286 size_t _rs_lengths_prediction;
287
288 size_t _known_garbage_bytes;
289 double _known_garbage_ratio;
290
291 double sigma() {
292 return _sigma;
293 }
294
295 // A function that prevents us putting too much stock in small sample
296 // sets. Returns a number between 2.0 and 1.0, depending on the number
297 // of samples. 5 or more samples yields one; fewer scales linearly from
298 // 2.0 at 1 sample to 1.0 at 5.
299 double confidence_factor(int samples) {
300 if (samples > 4) return 1.0;
301 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
302 }
303
304 double get_new_neg_prediction(TruncatedSeq* seq) {
305 return seq->davg() - sigma() * seq->dsd();
306 }
307
308 #ifndef PRODUCT
309 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
310 #endif // PRODUCT
311
312 void adjust_concurrent_refinement(double update_rs_time,
313 double update_rs_processed_buffers,
314 double goal_ms);
315
316 protected:
317 double _pause_time_target_ms;
318 double _recorded_young_cset_choice_time_ms;
319 double _recorded_non_young_cset_choice_time_ms;
320 bool _within_target;
321 size_t _pending_cards;
322 size_t _max_pending_cards;
323
324 public:
325
326 void set_region_short_lived(HeapRegion* hr) {
327 hr->install_surv_rate_group(_short_lived_surv_rate_group);
328 }
329
330 void set_region_survivors(HeapRegion* hr) {
331 hr->install_surv_rate_group(_survivor_surv_rate_group);
332 }
333
334 #ifndef PRODUCT
335 bool verify_young_ages();
336 #endif // PRODUCT
337
338 double get_new_prediction(TruncatedSeq* seq) {
339 return MAX2(seq->davg() + sigma() * seq->dsd(),
340 seq->davg() * confidence_factor(seq->num()));
341 }
342
343 size_t young_cset_length() {
344 return _young_cset_length;
345 }
346
347 void record_max_rs_lengths(size_t rs_lengths) {
348 _max_rs_lengths = rs_lengths;
349 }
350
351 size_t predict_pending_card_diff() {
352 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
353 if (prediction < 0.00001)
354 return 0;
355 else
356 return (size_t) prediction;
357 }
358
359 size_t predict_pending_cards() {
360 size_t max_pending_card_num = _g1->max_pending_card_num();
361 size_t diff = predict_pending_card_diff();
362 size_t prediction;
363 if (diff > max_pending_card_num)
364 prediction = max_pending_card_num;
365 else
366 prediction = max_pending_card_num - diff;
367
368 return prediction;
369 }
370
371 size_t predict_rs_length_diff() {
372 return (size_t) get_new_prediction(_rs_length_diff_seq);
373 }
374
375 double predict_alloc_rate_ms() {
376 return get_new_prediction(_alloc_rate_ms_seq);
377 }
378
379 double predict_cost_per_card_ms() {
380 return get_new_prediction(_cost_per_card_ms_seq);
381 }
382
383 double predict_rs_update_time_ms(size_t pending_cards) {
384 return (double) pending_cards * predict_cost_per_card_ms();
385 }
386
387 double predict_fully_young_cards_per_entry_ratio() {
388 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
389 }
390
391 double predict_partially_young_cards_per_entry_ratio() {
392 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
393 return predict_fully_young_cards_per_entry_ratio();
394 else
395 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
396 }
397
398 size_t predict_young_card_num(size_t rs_length) {
399 return (size_t) ((double) rs_length *
400 predict_fully_young_cards_per_entry_ratio());
401 }
402
403 size_t predict_non_young_card_num(size_t rs_length) {
404 return (size_t) ((double) rs_length *
405 predict_partially_young_cards_per_entry_ratio());
406 }
407
408 double predict_rs_scan_time_ms(size_t card_num) {
409 if (full_young_gcs())
410 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
411 else
412 return predict_partially_young_rs_scan_time_ms(card_num);
413 }
414
415 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
416 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
417 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
418 else
419 return (double) card_num *
420 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
421 }
422
423 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
424 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
425 return 1.1 * (double) bytes_to_copy *
426 get_new_prediction(_cost_per_byte_ms_seq);
427 else
428 return (double) bytes_to_copy *
429 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
430 }
431
432 double predict_object_copy_time_ms(size_t bytes_to_copy) {
433 if (_in_marking_window && !_in_marking_window_im)
434 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
435 else
436 return (double) bytes_to_copy *
437 get_new_prediction(_cost_per_byte_ms_seq);
438 }
439
440 double predict_constant_other_time_ms() {
441 return get_new_prediction(_constant_other_time_ms_seq);
442 }
443
444 double predict_young_other_time_ms(size_t young_num) {
445 return
446 (double) young_num *
447 get_new_prediction(_young_other_cost_per_region_ms_seq);
448 }
449
450 double predict_non_young_other_time_ms(size_t non_young_num) {
451 return
452 (double) non_young_num *
453 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
454 }
455
456 void check_if_region_is_too_expensive(double predicted_time_ms);
457
458 double predict_young_collection_elapsed_time_ms(size_t adjustment);
459 double predict_base_elapsed_time_ms(size_t pending_cards);
460 double predict_base_elapsed_time_ms(size_t pending_cards,
461 size_t scanned_cards);
462 size_t predict_bytes_to_copy(HeapRegion* hr);
463 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
464
465 // for use by: calculate_young_list_target_length(rs_length)
466 bool predict_will_fit(size_t young_region_num,
467 double base_time_ms,
468 size_t init_free_regions,
469 double target_pause_time_ms);
470
471 void start_recording_regions();
472 void record_cset_region_info(HeapRegion* hr, bool young);
473 void record_non_young_cset_region(HeapRegion* hr);
474
475 void set_recorded_young_regions(size_t n_regions);
476 void set_recorded_young_bytes(size_t bytes);
477 void set_recorded_rs_lengths(size_t rs_lengths);
478 void set_predicted_bytes_to_copy(size_t bytes);
479
480 void end_recording_regions();
481
482 void record_vtime_diff_ms(double vtime_diff_ms) {
483 _vtime_diff_ms = vtime_diff_ms;
484 }
485
486 void record_young_free_cset_time_ms(double time_ms) {
487 _recorded_young_free_cset_time_ms = time_ms;
488 }
489
490 void record_non_young_free_cset_time_ms(double time_ms) {
491 _recorded_non_young_free_cset_time_ms = time_ms;
492 }
493
494 double predict_young_gc_eff() {
495 return get_new_neg_prediction(_young_gc_eff_seq);
496 }
497
498 double predict_survivor_regions_evac_time();
499
500 // </NEW PREDICTION>
501
502 public:
503 void cset_regions_freed() {
504 bool propagate = _last_young_gc_full && !_in_marking_window;
505 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
506 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
507 // also call it on any more surv rate groups
508 }
509
510 void set_known_garbage_bytes(size_t known_garbage_bytes) {
511 _known_garbage_bytes = known_garbage_bytes;
512 size_t heap_bytes = _g1->capacity();
513 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
514 }
515
516 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
517 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
518
519 _known_garbage_bytes -= known_garbage_bytes;
520 size_t heap_bytes = _g1->capacity();
521 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
522 }
523
524 G1MMUTracker* mmu_tracker() {
525 return _mmu_tracker;
526 }
527
528 double max_pause_time_ms() {
529 return _mmu_tracker->max_gc_time() * 1000.0;
530 }
531
532 double predict_init_time_ms() {
533 return get_new_prediction(_concurrent_mark_init_times_ms);
534 }
535
536 double predict_remark_time_ms() {
537 return get_new_prediction(_concurrent_mark_remark_times_ms);
538 }
539
540 double predict_cleanup_time_ms() {
541 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
542 }
543
544 // Returns an estimate of the survival rate of the region at yg-age
545 // "yg_age".
546 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
547 TruncatedSeq* seq = surv_rate_group->get_seq(age);
548 if (seq->num() == 0)
549 gclog_or_tty->print("BARF! age is %d", age);
550 guarantee( seq->num() > 0, "invariant" );
551 double pred = get_new_prediction(seq);
552 if (pred > 1.0)
553 pred = 1.0;
554 return pred;
555 }
556
557 double predict_yg_surv_rate(int age) {
558 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
559 }
560
561 double accum_yg_surv_rate_pred(int age) {
562 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
563 }
564
565 protected:
566 void print_stats(int level, const char* str, double value);
567 void print_stats(int level, const char* str, int value);
568
569 void print_par_stats(int level, const char* str, double* data);
570 void print_par_sizes(int level, const char* str, double* data);
571
572 void check_other_times(int level,
573 NumberSeq* other_times_ms,
574 NumberSeq* calc_other_times_ms) const;
575
576 void print_summary (PauseSummary* stats) const;
577
578 void print_summary (int level, const char* str, NumberSeq* seq) const;
579 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
580
581 double avg_value (double* data);
582 double max_value (double* data);
583 double sum_of_values (double* data);
584 double max_sum (double* data1, double* data2);
585
586 int _last_satb_drain_processed_buffers;
587 int _last_update_rs_processed_buffers;
588 double _last_pause_time_ms;
589
590 size_t _bytes_in_to_space_before_gc;
591 size_t _bytes_in_to_space_after_gc;
592 size_t bytes_in_to_space_during_gc() {
593 return
594 _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc;
595 }
596 size_t _bytes_in_collection_set_before_gc;
597 // Used to count used bytes in CS.
598 friend class CountCSClosure;
599
600 // Statistics kept per GC stoppage, pause or full.
601 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
602
603 // We track markings.
604 int _num_markings;
605 double _mark_thread_startup_sec; // Time at startup of marking thread
606
607 // Add a new GC of the given duration and end time to the record.
608 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
609
610 // The head of the list (via "next_in_collection_set()") representing the
611 // current collection set. Set from the incrementally built collection
612 // set at the start of the pause.
613 HeapRegion* _collection_set;
614
615 // The number of regions in the collection set. Set from the incrementally
616 // built collection set at the start of an evacuation pause.
617 size_t _collection_set_size;
618
619 // The number of bytes in the collection set before the pause. Set from
620 // the incrementally built collection set at the start of an evacuation
621 // pause.
622 size_t _collection_set_bytes_used_before;
623
624 // The associated information that is maintained while the incremental
625 // collection set is being built with young regions. Used to populate
626 // the recorded info for the evacuation pause.
627
628 enum CSetBuildType {
629 Active, // We are actively building the collection set
630 Inactive // We are not actively building the collection set
631 };
632
633 CSetBuildType _inc_cset_build_state;
634
635 // The head of the incrementally built collection set.
636 HeapRegion* _inc_cset_head;
637
638 // The tail of the incrementally built collection set.
639 HeapRegion* _inc_cset_tail;
640
641 // The number of regions in the incrementally built collection set.
642 // Used to set _collection_set_size at the start of an evacuation
643 // pause.
644 size_t _inc_cset_size;
645
646 // Used as the index in the surving young words structure
647 // which tracks the amount of space, for each young region,
648 // that survives the pause.
649 size_t _inc_cset_young_index;
650
651 // The number of bytes in the incrementally built collection set.
652 // Used to set _collection_set_bytes_used_before at the start of
653 // an evacuation pause.
654 size_t _inc_cset_bytes_used_before;
655
656 // Used to record the highest end of heap region in collection set
657 HeapWord* _inc_cset_max_finger;
658
659 // The number of recorded used bytes in the young regions
660 // of the collection set. This is the sum of the used() bytes
661 // of retired young regions in the collection set.
662 size_t _inc_cset_recorded_young_bytes;
663
664 // The RSet lengths recorded for regions in the collection set
665 // (updated by the periodic sampling of the regions in the
666 // young list/collection set).
667 size_t _inc_cset_recorded_rs_lengths;
668
669 // The predicted elapsed time it will take to collect the regions
670 // in the collection set (updated by the periodic sampling of the
671 // regions in the young list/collection set).
672 double _inc_cset_predicted_elapsed_time_ms;
673
674 // The predicted bytes to copy for the regions in the collection
675 // set (updated by the periodic sampling of the regions in the
676 // young list/collection set).
677 size_t _inc_cset_predicted_bytes_to_copy;
678
679 // Info about marking.
680 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
681
682 // The number of collection pauses at the end of the last mark.
683 size_t _n_pauses_at_mark_end;
684
685 // Stash a pointer to the g1 heap.
686 G1CollectedHeap* _g1;
687
688 // The average time in ms per collection pause, averaged over recent pauses.
689 double recent_avg_time_for_pauses_ms();
690
691 // The average time in ms for RS scanning, per pause, averaged
692 // over recent pauses. (Note the RS scanning time for a pause
693 // is itself an average of the RS scanning time for each worker
694 // thread.)
695 double recent_avg_time_for_rs_scan_ms();
696
697 // The number of "recent" GCs recorded in the number sequences
698 int number_of_recent_gcs();
699
700 // The average survival ratio, computed by the total number of bytes
701 // suriviving / total number of bytes before collection over the last
702 // several recent pauses.
703 double recent_avg_survival_fraction();
704 // The survival fraction of the most recent pause; if there have been no
705 // pauses, returns 1.0.
706 double last_survival_fraction();
707
708 // Returns a "conservative" estimate of the recent survival rate, i.e.,
709 // one that may be higher than "recent_avg_survival_fraction".
710 // This is conservative in several ways:
711 // If there have been few pauses, it will assume a potential high
712 // variance, and err on the side of caution.
713 // It puts a lower bound (currently 0.1) on the value it will return.
714 // To try to detect phase changes, if the most recent pause ("latest") has a
715 // higher-than average ("avg") survival rate, it returns that rate.
716 // "work" version is a utility function; young is restricted to young regions.
717 double conservative_avg_survival_fraction_work(double avg,
718 double latest);
719
720 // The arguments are the two sequences that keep track of the number of bytes
721 // surviving and the total number of bytes before collection, resp.,
722 // over the last evereal recent pauses
723 // Returns the survival rate for the category in the most recent pause.
724 // If there have been no pauses, returns 1.0.
725 double last_survival_fraction_work(TruncatedSeq* surviving,
726 TruncatedSeq* before);
727
728 // The arguments are the two sequences that keep track of the number of bytes
729 // surviving and the total number of bytes before collection, resp.,
730 // over the last several recent pauses
731 // Returns the average survival ration over the last several recent pauses
732 // If there have been no pauses, return 1.0
733 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
734 TruncatedSeq* before);
735
736 double conservative_avg_survival_fraction() {
737 double avg = recent_avg_survival_fraction();
738 double latest = last_survival_fraction();
739 return conservative_avg_survival_fraction_work(avg, latest);
740 }
741
742 // The ratio of gc time to elapsed time, computed over recent pauses.
743 double _recent_avg_pause_time_ratio;
744
745 double recent_avg_pause_time_ratio() {
746 return _recent_avg_pause_time_ratio;
747 }
748
749 // Number of pauses between concurrent marking.
750 size_t _pauses_btwn_concurrent_mark;
751
752 size_t _n_marks_since_last_pause;
753
754 // At the end of a pause we check the heap occupancy and we decide
755 // whether we will start a marking cycle during the next pause. If
756 // we decide that we want to do that, we will set this parameter to
757 // true. So, this parameter will stay true between the end of a
758 // pause and the beginning of a subsequent pause (not necessarily
759 // the next one, see the comments on the next field) when we decide
760 // that we will indeed start a marking cycle and do the initial-mark
761 // work.
762 volatile bool _initiate_conc_mark_if_possible;
763
764 // If initiate_conc_mark_if_possible() is set at the beginning of a
765 // pause, it is a suggestion that the pause should start a marking
766 // cycle by doing the initial-mark work. However, it is possible
767 // that the concurrent marking thread is still finishing up the
768 // previous marking cycle (e.g., clearing the next marking
769 // bitmap). If that is the case we cannot start a new cycle and
770 // we'll have to wait for the concurrent marking thread to finish
771 // what it is doing. In this case we will postpone the marking cycle
772 // initiation decision for the next pause. When we eventually decide
773 // to start a cycle, we will set _during_initial_mark_pause which
774 // will stay true until the end of the initial-mark pause and it's
775 // the condition that indicates that a pause is doing the
776 // initial-mark work.
777 volatile bool _during_initial_mark_pause;
778
779 bool _should_revert_to_full_young_gcs;
780 bool _last_full_young_gc;
781
782 // This set of variables tracks the collector efficiency, in order to
783 // determine whether we should initiate a new marking.
784 double _cur_mark_stop_world_time_ms;
785 double _mark_init_start_sec;
786 double _mark_remark_start_sec;
787 double _mark_cleanup_start_sec;
788 double _mark_closure_time_ms;
789
790 void calculate_young_list_min_length();
791 void calculate_young_list_target_length();
792 void calculate_young_list_target_length(size_t rs_lengths);
793
794 public:
795
796 G1CollectorPolicy();
797
798 virtual G1CollectorPolicy* as_g1_policy() { return this; }
799
800 virtual CollectorPolicy::Name kind() {
801 return CollectorPolicy::G1CollectorPolicyKind;
802 }
803
804 void check_prediction_validity();
805
806 size_t bytes_in_collection_set() {
807 return _bytes_in_collection_set_before_gc;
808 }
809
810 size_t bytes_in_to_space() {
811 return bytes_in_to_space_during_gc();
812 }
813
814 unsigned calc_gc_alloc_time_stamp() {
815 return _all_pause_times_ms->num() + 1;
816 }
817
818 protected:
819
820 // Count the number of bytes used in the CS.
821 void count_CS_bytes_used();
822
823 // Together these do the base cleanup-recording work. Subclasses might
824 // want to put something between them.
825 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
826 size_t max_live_bytes);
827 void record_concurrent_mark_cleanup_end_work2();
828
829 public:
830
831 virtual void init();
832
833 // Create jstat counters for the policy.
834 virtual void initialize_gc_policy_counters();
835
836 virtual HeapWord* mem_allocate_work(size_t size,
837 bool is_tlab,
838 bool* gc_overhead_limit_was_exceeded);
839
840 // This method controls how a collector handles one or more
841 // of its generations being fully allocated.
842 virtual HeapWord* satisfy_failed_allocation(size_t size,
843 bool is_tlab);
844
845 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
846
847 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
848
849 // The number of collection pauses so far.
850 long n_pauses() const { return _n_pauses; }
851
852 // Update the heuristic info to record a collection pause of the given
853 // start time, where the given number of bytes were used at the start.
854 // This may involve changing the desired size of a collection set.
855
856 virtual void record_stop_world_start();
857
858 virtual void record_collection_pause_start(double start_time_sec,
859 size_t start_used);
860
861 // Must currently be called while the world is stopped.
862 virtual void record_concurrent_mark_init_start();
863 virtual void record_concurrent_mark_init_end();
864 void record_concurrent_mark_init_end_pre(double
865 mark_init_elapsed_time_ms);
866
867 void record_mark_closure_time(double mark_closure_time_ms);
868
869 virtual void record_concurrent_mark_remark_start();
870 virtual void record_concurrent_mark_remark_end();
871
872 virtual void record_concurrent_mark_cleanup_start();
873 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
874 size_t max_live_bytes);
875 virtual void record_concurrent_mark_cleanup_completed();
876
877 virtual void record_concurrent_pause();
878 virtual void record_concurrent_pause_end();
879
880 virtual void record_collection_pause_end();
881 void print_heap_transition();
882
883 // Record the fact that a full collection occurred.
884 virtual void record_full_collection_start();
885 virtual void record_full_collection_end();
886
887 void record_gc_worker_start_time(int worker_i, double ms) {
888 _par_last_gc_worker_start_times_ms[worker_i] = ms;
889 }
890
891 void record_ext_root_scan_time(int worker_i, double ms) {
892 _par_last_ext_root_scan_times_ms[worker_i] = ms;
893 }
894
895 void record_mark_stack_scan_time(int worker_i, double ms) {
896 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
897 }
898
899 void record_satb_drain_time(double ms) {
900 _cur_satb_drain_time_ms = ms;
901 _satb_drain_time_set = true;
902 }
903
904 void record_satb_drain_processed_buffers (int processed_buffers) {
905 _last_satb_drain_processed_buffers = processed_buffers;
906 }
907
908 void record_mod_union_time(double ms) {
909 _all_mod_union_times_ms->add(ms);
910 }
911
912 void record_update_rs_time(int thread, double ms) {
913 _par_last_update_rs_times_ms[thread] = ms;
914 }
915
916 void record_update_rs_processed_buffers (int thread,
917 double processed_buffers) {
918 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
919 }
920
921 void record_scan_rs_time(int thread, double ms) {
922 _par_last_scan_rs_times_ms[thread] = ms;
923 }
924
925 void reset_obj_copy_time(int thread) {
926 _par_last_obj_copy_times_ms[thread] = 0.0;
927 }
928
929 void reset_obj_copy_time() {
930 reset_obj_copy_time(0);
931 }
932
933 void record_obj_copy_time(int thread, double ms) {
934 _par_last_obj_copy_times_ms[thread] += ms;
935 }
936
937 void record_termination(int thread, double ms, size_t attempts) {
938 _par_last_termination_times_ms[thread] = ms;
939 _par_last_termination_attempts[thread] = (double) attempts;
940 }
941
942 void record_gc_worker_end_time(int worker_i, double ms) {
943 _par_last_gc_worker_end_times_ms[worker_i] = ms;
944 }
945
946 void record_pause_time_ms(double ms) {
947 _last_pause_time_ms = ms;
948 }
949
950 void record_clear_ct_time(double ms) {
951 _cur_clear_ct_time_ms = ms;
952 }
953
954 void record_par_time(double ms) {
955 _cur_collection_par_time_ms = ms;
956 }
957
958 void record_aux_start_time(int i) {
959 guarantee(i < _aux_num, "should be within range");
960 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
961 }
962
963 void record_aux_end_time(int i) {
964 guarantee(i < _aux_num, "should be within range");
965 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
966 _cur_aux_times_set[i] = true;
967 _cur_aux_times_ms[i] += ms;
968 }
969
970 void record_ref_proc_time(double ms) {
971 _cur_ref_proc_time_ms = ms;
972 }
973
974 void record_ref_enq_time(double ms) {
975 _cur_ref_enq_time_ms = ms;
976 }
977
978 #ifndef PRODUCT
979 void record_cc_clear_time(double ms) {
980 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
981 _min_clear_cc_time_ms = ms;
982 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
983 _max_clear_cc_time_ms = ms;
984 _cur_clear_cc_time_ms = ms;
985 _cum_clear_cc_time_ms += ms;
986 _num_cc_clears++;
987 }
988 #endif
989
990 // Record the fact that "bytes" bytes allocated in a region.
991 void record_before_bytes(size_t bytes);
992 void record_after_bytes(size_t bytes);
993
994 // Choose a new collection set. Marks the chosen regions as being
995 // "in_collection_set", and links them together. The head and number of
996 // the collection set are available via access methods.
997 virtual void choose_collection_set(double target_pause_time_ms) = 0;
998
999 // The head of the list (via "next_in_collection_set()") representing the
1000 // current collection set.
1001 HeapRegion* collection_set() { return _collection_set; }
1002
1003 void clear_collection_set() { _collection_set = NULL; }
1004
1005 // The number of elements in the current collection set.
1006 size_t collection_set_size() { return _collection_set_size; }
1007
1008 // Add "hr" to the CS.
1009 void add_to_collection_set(HeapRegion* hr);
1010
1011 // Incremental CSet Support
1012
1013 // The head of the incrementally built collection set.
1014 HeapRegion* inc_cset_head() { return _inc_cset_head; }
1015
1016 // The tail of the incrementally built collection set.
1017 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
1018
1019 // The number of elements in the incrementally built collection set.
1020 size_t inc_cset_size() { return _inc_cset_size; }
1021
1022 // Initialize incremental collection set info.
1023 void start_incremental_cset_building();
1024
1025 void clear_incremental_cset() {
1026 _inc_cset_head = NULL;
1027 _inc_cset_tail = NULL;
1028 }
1029
1030 // Stop adding regions to the incremental collection set
1031 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
1032
1033 // Add/remove information about hr to the aggregated information
1034 // for the incrementally built collection set.
1035 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
1036 void remove_from_incremental_cset_info(HeapRegion* hr);
1037
1038 // Update information about hr in the aggregated information for
1039 // the incrementally built collection set.
1040 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
1041
1042 private:
1043 // Update the incremental cset information when adding a region
1044 // (should not be called directly).
1045 void add_region_to_incremental_cset_common(HeapRegion* hr);
1046
1047 public:
1048 // Add hr to the LHS of the incremental collection set.
1049 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1050
1051 // Add hr to the RHS of the incremental collection set.
1052 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1053
1054 #ifndef PRODUCT
1055 void print_collection_set(HeapRegion* list_head, outputStream* st);
1056 #endif // !PRODUCT
1057
1058 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1059 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1060 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1061
1062 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1063 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1064 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1065
1066 // This sets the initiate_conc_mark_if_possible() flag to start a
1067 // new cycle, as long as we are not already in one. It's best if it
1068 // is called during a safepoint when the test whether a cycle is in
1069 // progress or not is stable.
1070 bool force_initial_mark_if_outside_cycle();
1071
1072 // This is called at the very beginning of an evacuation pause (it
1073 // has to be the first thing that the pause does). If
1074 // initiate_conc_mark_if_possible() is true, and the concurrent
1075 // marking thread has completed its work during the previous cycle,
1076 // it will set during_initial_mark_pause() to so that the pause does
1077 // the initial-mark work and start a marking cycle.
1078 void decide_on_conc_mark_initiation();
1079
1080 // If an expansion would be appropriate, because recent GC overhead had
1081 // exceeded the desired limit, return an amount to expand by.
1082 virtual size_t expansion_amount();
1083
1084 // note start of mark thread
1085 void note_start_of_mark_thread();
1086
1087 // The marked bytes of the "r" has changed; reclassify it's desirability
1088 // for marking. Also asserts that "r" is eligible for a CS.
1089 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
1090
1091 #ifndef PRODUCT
1092 // Check any appropriate marked bytes info, asserting false if
1093 // something's wrong, else returning "true".
1094 virtual bool assertMarkedBytesDataOK() = 0;
1095 #endif
1096
1097 // Print tracing information.
1098 void print_tracing_info() const;
1099
1100 // Print stats on young survival ratio
1101 void print_yg_surv_rate_info() const;
1102
1103 void finished_recalculating_age_indexes(bool is_survivors) {
1104 if (is_survivors) {
1105 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1106 } else {
1107 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1108 }
1109 // do that for any other surv rate groups
1110 }
1111
1112 bool is_young_list_full() {
1113 size_t young_list_length = _g1->young_list()->length();
1114 size_t young_list_target_length = _young_list_target_length;
1115 if (G1FixedEdenSize) {
1116 young_list_target_length -= _max_survivor_regions;
1117 }
1118 return young_list_length >= young_list_target_length;
1119 }
1120
1121 bool can_expand_young_list() {
1122 size_t young_list_length = _g1->young_list()->length();
1123 size_t young_list_max_length = _young_list_max_length;
1124 if (G1FixedEdenSize) {
1125 young_list_max_length -= _max_survivor_regions;
1126 }
1127 return young_list_length < young_list_max_length;
1128 }
1129
1130 void update_region_num(bool young);
1131
1132 bool in_young_gc_mode() {
1133 return _in_young_gc_mode;
1134 }
1135 void set_in_young_gc_mode(bool in_young_gc_mode) {
1136 _in_young_gc_mode = in_young_gc_mode;
1137 }
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 inline GCAllocPurpose alternative_purpose(int purpose) {
1207 return GCAllocForTenured;
1208 }
1209
1210 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1211
1212 size_t max_regions(int purpose);
1213
1214 // The limit on regions for a particular purpose is reached.
1215 void note_alloc_region_limit_reached(int purpose) {
1216 if (purpose == GCAllocForSurvived) {
1217 _tenuring_threshold = 0;
1218 }
1219 }
1220
1221 void note_start_adding_survivor_regions() {
1222 _survivor_surv_rate_group->start_adding_regions();
1223 }
1224
1225 void note_stop_adding_survivor_regions() {
1226 _survivor_surv_rate_group->stop_adding_regions();
1227 }
1228
1229 void record_survivor_regions(size_t regions,
1230 HeapRegion* head,
1231 HeapRegion* tail) {
1232 _recorded_survivor_regions = regions;
1233 _recorded_survivor_head = head;
1234 _recorded_survivor_tail = tail;
1235 }
1236
1237 size_t recorded_survivor_regions() {
1238 return _recorded_survivor_regions;
1239 }
1240
1241 void record_thread_age_table(ageTable* age_table)
1242 {
1243 _survivors_age_table.merge_par(age_table);
1244 }
1245
1246 void calculate_max_gc_locker_expansion();
1247
1248 // Calculates survivor space parameters.
1249 void calculate_survivors_policy();
1250
1251 };
1252
1253 // This encapsulates a particular strategy for a g1 Collector.
1254 //
1255 // Start a concurrent mark when our heap size is n bytes
1256 // greater then our heap size was at the last concurrent
1257 // mark. Where n is a function of the CMSTriggerRatio
1258 // and the MinHeapFreeRatio.
1259 //
1260 // Start a g1 collection pause when we have allocated the
1261 // average number of bytes currently being freed in
1262 // a collection, but only if it is at least one region
1263 // full
1264 //
1265 // Resize Heap based on desired
1266 // allocation space, where desired allocation space is
1267 // a function of survival rate and desired future to size.
1268 //
1269 // Choose collection set by first picking all older regions
1270 // which have a survival rate which beats our projected young
1271 // survival rate. Then fill out the number of needed regions
1272 // with young regions.
1273
1274 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1275 CollectionSetChooser* _collectionSetChooser;
1276 // If the estimated is less then desirable, resize if possible.
1277 void expand_if_possible(size_t numRegions);
1278
1279 virtual void choose_collection_set(double target_pause_time_ms);
1280 virtual void record_collection_pause_start(double start_time_sec,
1281 size_t start_used);
1282 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1283 size_t max_live_bytes);
1284 virtual void record_full_collection_end();
1285
1286 public:
1287 G1CollectorPolicy_BestRegionsFirst() {
1288 _collectionSetChooser = new CollectionSetChooser();
1289 }
1290 void record_collection_pause_end();
1291 // This is not needed any more, after the CSet choosing code was
1292 // changed to use the pause prediction work. But let's leave the
1293 // hook in just in case.
1294 void note_change_in_marked_bytes(HeapRegion* r) { }
1295 #ifndef PRODUCT
1296 bool assertMarkedBytesDataOK();
1297 #endif
1298 };
1299
1300 // This should move to some place more general...
1301
1302 // If we have "n" measurements, and we've kept track of their "sum" and the
1303 // "sum_of_squares" of the measurements, this returns the variance of the
1304 // sequence.
1305 inline double variance(int n, double sum_of_squares, double sum) {
1306 double n_d = (double)n;
1307 double avg = sum/n_d;
1308 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1309 }
1310
1311 // Local Variables: ***
1312 // c-indentation-style: gnu ***
1313 // End: ***
1314
1315 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP