Mon, 31 Aug 2009 05:27:29 -0700
6841313: G1: dirty cards of survivor regions in parallel
Reviewed-by: tonyp, iveresov
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // A G1CollectorPolicy makes policy decisions that determine the
26 // characteristics of the collector. Examples include:
27 // * choice of collection set.
28 // * when to collect.
30 class HeapRegion;
31 class CollectionSetChooser;
33 // Yes, this is a bit unpleasant... but it saves replicating the same thing
34 // over and over again and introducing subtle problems through small typos and
35 // cutting and pasting mistakes. The macros below introduces a number
36 // sequnce into the following two classes and the methods that access it.
38 #define define_num_seq(name) \
39 private: \
40 NumberSeq _all_##name##_times_ms; \
41 public: \
42 void record_##name##_time_ms(double ms) { \
43 _all_##name##_times_ms.add(ms); \
44 } \
45 NumberSeq* get_##name##_seq() { \
46 return &_all_##name##_times_ms; \
47 }
49 class MainBodySummary;
51 class PauseSummary: public CHeapObj {
52 define_num_seq(total)
53 define_num_seq(other)
55 public:
56 virtual MainBodySummary* main_body_summary() { return NULL; }
57 };
59 class MainBodySummary: public CHeapObj {
60 define_num_seq(satb_drain) // optional
61 define_num_seq(parallel) // parallel only
62 define_num_seq(ext_root_scan)
63 define_num_seq(mark_stack_scan)
64 define_num_seq(scan_only)
65 define_num_seq(update_rs)
66 define_num_seq(scan_rs)
67 define_num_seq(scan_new_refs) // Only for temp use; added to
68 // in parallel case.
69 define_num_seq(obj_copy)
70 define_num_seq(termination) // parallel only
71 define_num_seq(parallel_other) // parallel only
72 define_num_seq(mark_closure)
73 define_num_seq(clear_ct) // parallel only
74 };
76 class Summary: public PauseSummary,
77 public MainBodySummary {
78 public:
79 virtual MainBodySummary* main_body_summary() { return this; }
80 };
82 class AbandonedSummary: public PauseSummary {
83 };
85 class G1CollectorPolicy: public CollectorPolicy {
86 protected:
87 // The number of pauses during the execution.
88 long _n_pauses;
90 // either equal to the number of parallel threads, if ParallelGCThreads
91 // has been set, or 1 otherwise
92 int _parallel_gc_threads;
94 enum SomePrivateConstants {
95 NumPrevPausesForHeuristics = 10,
96 NumPrevGCsForHeuristics = 10,
97 NumAPIs = HeapRegion::MaxAge
98 };
100 G1MMUTracker* _mmu_tracker;
102 void initialize_flags();
104 void initialize_all() {
105 initialize_flags();
106 initialize_size_info();
107 initialize_perm_generation(PermGen::MarkSweepCompact);
108 }
110 virtual size_t default_init_heap_size() {
111 // Pick some reasonable default.
112 return 8*M;
113 }
115 double _cur_collection_start_sec;
116 size_t _cur_collection_pause_used_at_start_bytes;
117 size_t _cur_collection_pause_used_regions_at_start;
118 size_t _prev_collection_pause_used_at_end_bytes;
119 double _cur_collection_par_time_ms;
120 double _cur_satb_drain_time_ms;
121 double _cur_clear_ct_time_ms;
122 bool _satb_drain_time_set;
124 #ifndef PRODUCT
125 // Card Table Count Cache stats
126 double _min_clear_cc_time_ms; // min
127 double _max_clear_cc_time_ms; // max
128 double _cur_clear_cc_time_ms; // clearing time during current pause
129 double _cum_clear_cc_time_ms; // cummulative clearing time
130 jlong _num_cc_clears; // number of times the card count cache has been cleared
131 #endif
133 double _cur_CH_strong_roots_end_sec;
134 double _cur_CH_strong_roots_dur_ms;
135 double _cur_G1_strong_roots_end_sec;
136 double _cur_G1_strong_roots_dur_ms;
138 // Statistics for recent GC pauses. See below for how indexed.
139 TruncatedSeq* _recent_CH_strong_roots_times_ms;
140 TruncatedSeq* _recent_G1_strong_roots_times_ms;
141 TruncatedSeq* _recent_evac_times_ms;
142 // These exclude marking times.
143 TruncatedSeq* _recent_pause_times_ms;
144 TruncatedSeq* _recent_gc_times_ms;
146 TruncatedSeq* _recent_CS_bytes_used_before;
147 TruncatedSeq* _recent_CS_bytes_surviving;
149 TruncatedSeq* _recent_rs_sizes;
151 TruncatedSeq* _concurrent_mark_init_times_ms;
152 TruncatedSeq* _concurrent_mark_remark_times_ms;
153 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
155 Summary* _summary;
156 AbandonedSummary* _abandoned_summary;
158 NumberSeq* _all_pause_times_ms;
159 NumberSeq* _all_full_gc_times_ms;
160 double _stop_world_start;
161 NumberSeq* _all_stop_world_times_ms;
162 NumberSeq* _all_yield_times_ms;
164 size_t _region_num_young;
165 size_t _region_num_tenured;
166 size_t _prev_region_num_young;
167 size_t _prev_region_num_tenured;
169 NumberSeq* _all_mod_union_times_ms;
171 int _aux_num;
172 NumberSeq* _all_aux_times_ms;
173 double* _cur_aux_start_times_ms;
174 double* _cur_aux_times_ms;
175 bool* _cur_aux_times_set;
177 double* _par_last_ext_root_scan_times_ms;
178 double* _par_last_mark_stack_scan_times_ms;
179 double* _par_last_scan_only_times_ms;
180 double* _par_last_scan_only_regions_scanned;
181 double* _par_last_update_rs_start_times_ms;
182 double* _par_last_update_rs_times_ms;
183 double* _par_last_update_rs_processed_buffers;
184 double* _par_last_scan_rs_start_times_ms;
185 double* _par_last_scan_rs_times_ms;
186 double* _par_last_scan_new_refs_times_ms;
187 double* _par_last_obj_copy_times_ms;
188 double* _par_last_termination_times_ms;
190 // indicates that we are in young GC mode
191 bool _in_young_gc_mode;
193 // indicates whether we are in full young or partially young GC mode
194 bool _full_young_gcs;
196 // if true, then it tries to dynamically adjust the length of the
197 // young list
198 bool _adaptive_young_list_length;
199 size_t _young_list_min_length;
200 size_t _young_list_target_length;
201 size_t _young_list_so_prefix_length;
202 size_t _young_list_fixed_length;
204 size_t _young_cset_length;
205 bool _last_young_gc_full;
207 double _target_pause_time_ms;
209 unsigned _full_young_pause_num;
210 unsigned _partial_young_pause_num;
212 bool _during_marking;
213 bool _in_marking_window;
214 bool _in_marking_window_im;
216 SurvRateGroup* _short_lived_surv_rate_group;
217 SurvRateGroup* _survivor_surv_rate_group;
218 // add here any more surv rate groups
220 bool during_marking() {
221 return _during_marking;
222 }
224 // <NEW PREDICTION>
226 private:
227 enum PredictionConstants {
228 TruncatedSeqLength = 10
229 };
231 TruncatedSeq* _alloc_rate_ms_seq;
232 double _prev_collection_pause_end_ms;
234 TruncatedSeq* _pending_card_diff_seq;
235 TruncatedSeq* _rs_length_diff_seq;
236 TruncatedSeq* _cost_per_card_ms_seq;
237 TruncatedSeq* _cost_per_scan_only_region_ms_seq;
238 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
239 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
240 TruncatedSeq* _cost_per_entry_ms_seq;
241 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
242 TruncatedSeq* _cost_per_byte_ms_seq;
243 TruncatedSeq* _constant_other_time_ms_seq;
244 TruncatedSeq* _young_other_cost_per_region_ms_seq;
245 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
247 TruncatedSeq* _pending_cards_seq;
248 TruncatedSeq* _scanned_cards_seq;
249 TruncatedSeq* _rs_lengths_seq;
251 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
252 TruncatedSeq* _cost_per_scan_only_region_ms_during_cm_seq;
254 TruncatedSeq* _young_gc_eff_seq;
256 TruncatedSeq* _max_conc_overhead_seq;
258 size_t _recorded_young_regions;
259 size_t _recorded_scan_only_regions;
260 size_t _recorded_non_young_regions;
261 size_t _recorded_region_num;
263 size_t _free_regions_at_end_of_collection;
264 size_t _scan_only_regions_at_end_of_collection;
266 size_t _recorded_rs_lengths;
267 size_t _max_rs_lengths;
269 size_t _recorded_marked_bytes;
270 size_t _recorded_young_bytes;
272 size_t _predicted_pending_cards;
273 size_t _predicted_cards_scanned;
274 size_t _predicted_rs_lengths;
275 size_t _predicted_bytes_to_copy;
277 double _predicted_survival_ratio;
278 double _predicted_rs_update_time_ms;
279 double _predicted_rs_scan_time_ms;
280 double _predicted_scan_only_scan_time_ms;
281 double _predicted_object_copy_time_ms;
282 double _predicted_constant_other_time_ms;
283 double _predicted_young_other_time_ms;
284 double _predicted_non_young_other_time_ms;
285 double _predicted_pause_time_ms;
287 double _vtime_diff_ms;
289 double _recorded_young_free_cset_time_ms;
290 double _recorded_non_young_free_cset_time_ms;
292 double _sigma;
293 double _expensive_region_limit_ms;
295 size_t _rs_lengths_prediction;
297 size_t _known_garbage_bytes;
298 double _known_garbage_ratio;
300 double sigma() {
301 return _sigma;
302 }
304 // A function that prevents us putting too much stock in small sample
305 // sets. Returns a number between 2.0 and 1.0, depending on the number
306 // of samples. 5 or more samples yields one; fewer scales linearly from
307 // 2.0 at 1 sample to 1.0 at 5.
308 double confidence_factor(int samples) {
309 if (samples > 4) return 1.0;
310 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
311 }
313 double get_new_neg_prediction(TruncatedSeq* seq) {
314 return seq->davg() - sigma() * seq->dsd();
315 }
317 #ifndef PRODUCT
318 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
319 #endif // PRODUCT
321 protected:
322 double _pause_time_target_ms;
323 double _recorded_young_cset_choice_time_ms;
324 double _recorded_non_young_cset_choice_time_ms;
325 bool _within_target;
326 size_t _pending_cards;
327 size_t _max_pending_cards;
329 public:
331 void set_region_short_lived(HeapRegion* hr) {
332 hr->install_surv_rate_group(_short_lived_surv_rate_group);
333 }
335 void set_region_survivors(HeapRegion* hr) {
336 hr->install_surv_rate_group(_survivor_surv_rate_group);
337 }
339 #ifndef PRODUCT
340 bool verify_young_ages();
341 #endif // PRODUCT
343 void tag_scan_only(size_t short_lived_scan_only_length);
345 double get_new_prediction(TruncatedSeq* seq) {
346 return MAX2(seq->davg() + sigma() * seq->dsd(),
347 seq->davg() * confidence_factor(seq->num()));
348 }
350 size_t young_cset_length() {
351 return _young_cset_length;
352 }
354 void record_max_rs_lengths(size_t rs_lengths) {
355 _max_rs_lengths = rs_lengths;
356 }
358 size_t predict_pending_card_diff() {
359 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
360 if (prediction < 0.00001)
361 return 0;
362 else
363 return (size_t) prediction;
364 }
366 size_t predict_pending_cards() {
367 size_t max_pending_card_num = _g1->max_pending_card_num();
368 size_t diff = predict_pending_card_diff();
369 size_t prediction;
370 if (diff > max_pending_card_num)
371 prediction = max_pending_card_num;
372 else
373 prediction = max_pending_card_num - diff;
375 return prediction;
376 }
378 size_t predict_rs_length_diff() {
379 return (size_t) get_new_prediction(_rs_length_diff_seq);
380 }
382 double predict_alloc_rate_ms() {
383 return get_new_prediction(_alloc_rate_ms_seq);
384 }
386 double predict_cost_per_card_ms() {
387 return get_new_prediction(_cost_per_card_ms_seq);
388 }
390 double predict_rs_update_time_ms(size_t pending_cards) {
391 return (double) pending_cards * predict_cost_per_card_ms();
392 }
394 double predict_fully_young_cards_per_entry_ratio() {
395 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
396 }
398 double predict_partially_young_cards_per_entry_ratio() {
399 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
400 return predict_fully_young_cards_per_entry_ratio();
401 else
402 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
403 }
405 size_t predict_young_card_num(size_t rs_length) {
406 return (size_t) ((double) rs_length *
407 predict_fully_young_cards_per_entry_ratio());
408 }
410 size_t predict_non_young_card_num(size_t rs_length) {
411 return (size_t) ((double) rs_length *
412 predict_partially_young_cards_per_entry_ratio());
413 }
415 double predict_rs_scan_time_ms(size_t card_num) {
416 if (full_young_gcs())
417 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
418 else
419 return predict_partially_young_rs_scan_time_ms(card_num);
420 }
422 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
423 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
424 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
425 else
426 return (double) card_num *
427 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
428 }
430 double predict_scan_only_time_ms_during_cm(size_t scan_only_region_num) {
431 if (_cost_per_scan_only_region_ms_during_cm_seq->num() < 3)
432 return 1.5 * (double) scan_only_region_num *
433 get_new_prediction(_cost_per_scan_only_region_ms_seq);
434 else
435 return (double) scan_only_region_num *
436 get_new_prediction(_cost_per_scan_only_region_ms_during_cm_seq);
437 }
439 double predict_scan_only_time_ms(size_t scan_only_region_num) {
440 if (_in_marking_window_im)
441 return predict_scan_only_time_ms_during_cm(scan_only_region_num);
442 else
443 return (double) scan_only_region_num *
444 get_new_prediction(_cost_per_scan_only_region_ms_seq);
445 }
447 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
448 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
449 return 1.1 * (double) bytes_to_copy *
450 get_new_prediction(_cost_per_byte_ms_seq);
451 else
452 return (double) bytes_to_copy *
453 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
454 }
456 double predict_object_copy_time_ms(size_t bytes_to_copy) {
457 if (_in_marking_window && !_in_marking_window_im)
458 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
459 else
460 return (double) bytes_to_copy *
461 get_new_prediction(_cost_per_byte_ms_seq);
462 }
464 double predict_constant_other_time_ms() {
465 return get_new_prediction(_constant_other_time_ms_seq);
466 }
468 double predict_young_other_time_ms(size_t young_num) {
469 return
470 (double) young_num *
471 get_new_prediction(_young_other_cost_per_region_ms_seq);
472 }
474 double predict_non_young_other_time_ms(size_t non_young_num) {
475 return
476 (double) non_young_num *
477 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
478 }
480 void check_if_region_is_too_expensive(double predicted_time_ms);
482 double predict_young_collection_elapsed_time_ms(size_t adjustment);
483 double predict_base_elapsed_time_ms(size_t pending_cards);
484 double predict_base_elapsed_time_ms(size_t pending_cards,
485 size_t scanned_cards);
486 size_t predict_bytes_to_copy(HeapRegion* hr);
487 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
489 // for use by: calculate_optimal_so_length(length)
490 void predict_gc_eff(size_t young_region_num,
491 size_t so_length,
492 double base_time_ms,
493 double *gc_eff,
494 double *pause_time_ms);
496 // for use by: calculate_young_list_target_config(rs_length)
497 bool predict_gc_eff(size_t young_region_num,
498 size_t so_length,
499 double base_time_with_so_ms,
500 size_t init_free_regions,
501 double target_pause_time_ms,
502 double* gc_eff);
504 void start_recording_regions();
505 void record_cset_region(HeapRegion* hr, bool young);
506 void record_scan_only_regions(size_t scan_only_length);
507 void end_recording_regions();
509 void record_vtime_diff_ms(double vtime_diff_ms) {
510 _vtime_diff_ms = vtime_diff_ms;
511 }
513 void record_young_free_cset_time_ms(double time_ms) {
514 _recorded_young_free_cset_time_ms = time_ms;
515 }
517 void record_non_young_free_cset_time_ms(double time_ms) {
518 _recorded_non_young_free_cset_time_ms = time_ms;
519 }
521 double predict_young_gc_eff() {
522 return get_new_neg_prediction(_young_gc_eff_seq);
523 }
525 double predict_survivor_regions_evac_time();
527 // </NEW PREDICTION>
529 public:
530 void cset_regions_freed() {
531 bool propagate = _last_young_gc_full && !_in_marking_window;
532 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
533 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
534 // also call it on any more surv rate groups
535 }
537 void set_known_garbage_bytes(size_t known_garbage_bytes) {
538 _known_garbage_bytes = known_garbage_bytes;
539 size_t heap_bytes = _g1->capacity();
540 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
541 }
543 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
544 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
546 _known_garbage_bytes -= known_garbage_bytes;
547 size_t heap_bytes = _g1->capacity();
548 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
549 }
551 G1MMUTracker* mmu_tracker() {
552 return _mmu_tracker;
553 }
555 double predict_init_time_ms() {
556 return get_new_prediction(_concurrent_mark_init_times_ms);
557 }
559 double predict_remark_time_ms() {
560 return get_new_prediction(_concurrent_mark_remark_times_ms);
561 }
563 double predict_cleanup_time_ms() {
564 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
565 }
567 // Returns an estimate of the survival rate of the region at yg-age
568 // "yg_age".
569 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
570 TruncatedSeq* seq = surv_rate_group->get_seq(age);
571 if (seq->num() == 0)
572 gclog_or_tty->print("BARF! age is %d", age);
573 guarantee( seq->num() > 0, "invariant" );
574 double pred = get_new_prediction(seq);
575 if (pred > 1.0)
576 pred = 1.0;
577 return pred;
578 }
580 double predict_yg_surv_rate(int age) {
581 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
582 }
584 double accum_yg_surv_rate_pred(int age) {
585 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
586 }
588 protected:
589 void print_stats (int level, const char* str, double value);
590 void print_stats (int level, const char* str, int value);
591 void print_par_stats (int level, const char* str, double* data) {
592 print_par_stats(level, str, data, true);
593 }
594 void print_par_stats (int level, const char* str, double* data, bool summary);
595 void print_par_buffers (int level, const char* str, double* data, bool summary);
597 void check_other_times(int level,
598 NumberSeq* other_times_ms,
599 NumberSeq* calc_other_times_ms) const;
601 void print_summary (PauseSummary* stats) const;
602 void print_abandoned_summary(PauseSummary* summary) const;
604 void print_summary (int level, const char* str, NumberSeq* seq) const;
605 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
607 double avg_value (double* data);
608 double max_value (double* data);
609 double sum_of_values (double* data);
610 double max_sum (double* data1, double* data2);
612 int _last_satb_drain_processed_buffers;
613 int _last_update_rs_processed_buffers;
614 double _last_pause_time_ms;
616 size_t _bytes_in_to_space_before_gc;
617 size_t _bytes_in_to_space_after_gc;
618 size_t bytes_in_to_space_during_gc() {
619 return
620 _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc;
621 }
622 size_t _bytes_in_collection_set_before_gc;
623 // Used to count used bytes in CS.
624 friend class CountCSClosure;
626 // Statistics kept per GC stoppage, pause or full.
627 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
629 // We track markings.
630 int _num_markings;
631 double _mark_thread_startup_sec; // Time at startup of marking thread
633 // Add a new GC of the given duration and end time to the record.
634 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
636 // The head of the list (via "next_in_collection_set()") representing the
637 // current collection set.
638 HeapRegion* _collection_set;
639 size_t _collection_set_size;
640 size_t _collection_set_bytes_used_before;
642 // Info about marking.
643 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
645 // The number of collection pauses at the end of the last mark.
646 size_t _n_pauses_at_mark_end;
648 // Stash a pointer to the g1 heap.
649 G1CollectedHeap* _g1;
651 // The average time in ms per collection pause, averaged over recent pauses.
652 double recent_avg_time_for_pauses_ms();
654 // The average time in ms for processing CollectedHeap strong roots, per
655 // collection pause, averaged over recent pauses.
656 double recent_avg_time_for_CH_strong_ms();
658 // The average time in ms for processing the G1 remembered set, per
659 // pause, averaged over recent pauses.
660 double recent_avg_time_for_G1_strong_ms();
662 // The average time in ms for "evacuating followers", per pause, averaged
663 // over recent pauses.
664 double recent_avg_time_for_evac_ms();
666 // The number of "recent" GCs recorded in the number sequences
667 int number_of_recent_gcs();
669 // The average survival ratio, computed by the total number of bytes
670 // suriviving / total number of bytes before collection over the last
671 // several recent pauses.
672 double recent_avg_survival_fraction();
673 // The survival fraction of the most recent pause; if there have been no
674 // pauses, returns 1.0.
675 double last_survival_fraction();
677 // Returns a "conservative" estimate of the recent survival rate, i.e.,
678 // one that may be higher than "recent_avg_survival_fraction".
679 // This is conservative in several ways:
680 // If there have been few pauses, it will assume a potential high
681 // variance, and err on the side of caution.
682 // It puts a lower bound (currently 0.1) on the value it will return.
683 // To try to detect phase changes, if the most recent pause ("latest") has a
684 // higher-than average ("avg") survival rate, it returns that rate.
685 // "work" version is a utility function; young is restricted to young regions.
686 double conservative_avg_survival_fraction_work(double avg,
687 double latest);
689 // The arguments are the two sequences that keep track of the number of bytes
690 // surviving and the total number of bytes before collection, resp.,
691 // over the last evereal recent pauses
692 // Returns the survival rate for the category in the most recent pause.
693 // If there have been no pauses, returns 1.0.
694 double last_survival_fraction_work(TruncatedSeq* surviving,
695 TruncatedSeq* before);
697 // The arguments are the two sequences that keep track of the number of bytes
698 // surviving and the total number of bytes before collection, resp.,
699 // over the last several recent pauses
700 // Returns the average survival ration over the last several recent pauses
701 // If there have been no pauses, return 1.0
702 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
703 TruncatedSeq* before);
705 double conservative_avg_survival_fraction() {
706 double avg = recent_avg_survival_fraction();
707 double latest = last_survival_fraction();
708 return conservative_avg_survival_fraction_work(avg, latest);
709 }
711 // The ratio of gc time to elapsed time, computed over recent pauses.
712 double _recent_avg_pause_time_ratio;
714 double recent_avg_pause_time_ratio() {
715 return _recent_avg_pause_time_ratio;
716 }
718 // Number of pauses between concurrent marking.
719 size_t _pauses_btwn_concurrent_mark;
721 size_t _n_marks_since_last_pause;
723 // True iff CM has been initiated.
724 bool _conc_mark_initiated;
726 // True iff CM should be initiated
727 bool _should_initiate_conc_mark;
728 bool _should_revert_to_full_young_gcs;
729 bool _last_full_young_gc;
731 // This set of variables tracks the collector efficiency, in order to
732 // determine whether we should initiate a new marking.
733 double _cur_mark_stop_world_time_ms;
734 double _mark_init_start_sec;
735 double _mark_remark_start_sec;
736 double _mark_cleanup_start_sec;
737 double _mark_closure_time_ms;
739 void calculate_young_list_min_length();
740 void calculate_young_list_target_config();
741 void calculate_young_list_target_config(size_t rs_lengths);
742 size_t calculate_optimal_so_length(size_t young_list_length);
744 public:
746 G1CollectorPolicy();
748 virtual G1CollectorPolicy* as_g1_policy() { return this; }
750 virtual CollectorPolicy::Name kind() {
751 return CollectorPolicy::G1CollectorPolicyKind;
752 }
754 void check_prediction_validity();
756 size_t bytes_in_collection_set() {
757 return _bytes_in_collection_set_before_gc;
758 }
760 size_t bytes_in_to_space() {
761 return bytes_in_to_space_during_gc();
762 }
764 unsigned calc_gc_alloc_time_stamp() {
765 return _all_pause_times_ms->num() + 1;
766 }
768 protected:
770 // Count the number of bytes used in the CS.
771 void count_CS_bytes_used();
773 // Together these do the base cleanup-recording work. Subclasses might
774 // want to put something between them.
775 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
776 size_t max_live_bytes);
777 void record_concurrent_mark_cleanup_end_work2();
779 public:
781 virtual void init();
783 // Create jstat counters for the policy.
784 virtual void initialize_gc_policy_counters();
786 virtual HeapWord* mem_allocate_work(size_t size,
787 bool is_tlab,
788 bool* gc_overhead_limit_was_exceeded);
790 // This method controls how a collector handles one or more
791 // of its generations being fully allocated.
792 virtual HeapWord* satisfy_failed_allocation(size_t size,
793 bool is_tlab);
795 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
797 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
799 // The number of collection pauses so far.
800 long n_pauses() const { return _n_pauses; }
802 // Update the heuristic info to record a collection pause of the given
803 // start time, where the given number of bytes were used at the start.
804 // This may involve changing the desired size of a collection set.
806 virtual void record_stop_world_start();
808 virtual void record_collection_pause_start(double start_time_sec,
809 size_t start_used);
811 // Must currently be called while the world is stopped.
812 virtual void record_concurrent_mark_init_start();
813 virtual void record_concurrent_mark_init_end();
814 void record_concurrent_mark_init_end_pre(double
815 mark_init_elapsed_time_ms);
817 void record_mark_closure_time(double mark_closure_time_ms);
819 virtual void record_concurrent_mark_remark_start();
820 virtual void record_concurrent_mark_remark_end();
822 virtual void record_concurrent_mark_cleanup_start();
823 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
824 size_t max_live_bytes);
825 virtual void record_concurrent_mark_cleanup_completed();
827 virtual void record_concurrent_pause();
828 virtual void record_concurrent_pause_end();
830 virtual void record_collection_pause_end_CH_strong_roots();
831 virtual void record_collection_pause_end_G1_strong_roots();
833 virtual void record_collection_pause_end(bool abandoned);
835 // Record the fact that a full collection occurred.
836 virtual void record_full_collection_start();
837 virtual void record_full_collection_end();
839 void record_ext_root_scan_time(int worker_i, double ms) {
840 _par_last_ext_root_scan_times_ms[worker_i] = ms;
841 }
843 void record_mark_stack_scan_time(int worker_i, double ms) {
844 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
845 }
847 void record_scan_only_time(int worker_i, double ms, int n) {
848 _par_last_scan_only_times_ms[worker_i] = ms;
849 _par_last_scan_only_regions_scanned[worker_i] = (double) n;
850 }
852 void record_satb_drain_time(double ms) {
853 _cur_satb_drain_time_ms = ms;
854 _satb_drain_time_set = true;
855 }
857 void record_satb_drain_processed_buffers (int processed_buffers) {
858 _last_satb_drain_processed_buffers = processed_buffers;
859 }
861 void record_mod_union_time(double ms) {
862 _all_mod_union_times_ms->add(ms);
863 }
865 void record_update_rs_start_time(int thread, double ms) {
866 _par_last_update_rs_start_times_ms[thread] = ms;
867 }
869 void record_update_rs_time(int thread, double ms) {
870 _par_last_update_rs_times_ms[thread] = ms;
871 }
873 void record_update_rs_processed_buffers (int thread,
874 double processed_buffers) {
875 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
876 }
878 void record_scan_rs_start_time(int thread, double ms) {
879 _par_last_scan_rs_start_times_ms[thread] = ms;
880 }
882 void record_scan_rs_time(int thread, double ms) {
883 _par_last_scan_rs_times_ms[thread] = ms;
884 }
886 void record_scan_new_refs_time(int thread, double ms) {
887 _par_last_scan_new_refs_times_ms[thread] = ms;
888 }
890 double get_scan_new_refs_time(int thread) {
891 return _par_last_scan_new_refs_times_ms[thread];
892 }
894 void reset_obj_copy_time(int thread) {
895 _par_last_obj_copy_times_ms[thread] = 0.0;
896 }
898 void reset_obj_copy_time() {
899 reset_obj_copy_time(0);
900 }
902 void record_obj_copy_time(int thread, double ms) {
903 _par_last_obj_copy_times_ms[thread] += ms;
904 }
906 void record_obj_copy_time(double ms) {
907 record_obj_copy_time(0, ms);
908 }
910 void record_termination_time(int thread, double ms) {
911 _par_last_termination_times_ms[thread] = ms;
912 }
914 void record_termination_time(double ms) {
915 record_termination_time(0, ms);
916 }
918 void record_pause_time_ms(double ms) {
919 _last_pause_time_ms = ms;
920 }
922 void record_clear_ct_time(double ms) {
923 _cur_clear_ct_time_ms = ms;
924 }
926 void record_par_time(double ms) {
927 _cur_collection_par_time_ms = ms;
928 }
930 void record_aux_start_time(int i) {
931 guarantee(i < _aux_num, "should be within range");
932 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
933 }
935 void record_aux_end_time(int i) {
936 guarantee(i < _aux_num, "should be within range");
937 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
938 _cur_aux_times_set[i] = true;
939 _cur_aux_times_ms[i] += ms;
940 }
942 #ifndef PRODUCT
943 void record_cc_clear_time(double ms) {
944 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
945 _min_clear_cc_time_ms = ms;
946 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
947 _max_clear_cc_time_ms = ms;
948 _cur_clear_cc_time_ms = ms;
949 _cum_clear_cc_time_ms += ms;
950 _num_cc_clears++;
951 }
952 #endif
954 // Record the fact that "bytes" bytes allocated in a region.
955 void record_before_bytes(size_t bytes);
956 void record_after_bytes(size_t bytes);
958 // Returns "true" if this is a good time to do a collection pause.
959 // The "word_size" argument, if non-zero, indicates the size of an
960 // allocation request that is prompting this query.
961 virtual bool should_do_collection_pause(size_t word_size) = 0;
963 // Choose a new collection set. Marks the chosen regions as being
964 // "in_collection_set", and links them together. The head and number of
965 // the collection set are available via access methods.
966 virtual void choose_collection_set() = 0;
968 void clear_collection_set() { _collection_set = NULL; }
970 // The head of the list (via "next_in_collection_set()") representing the
971 // current collection set.
972 HeapRegion* collection_set() { return _collection_set; }
974 // The number of elements in the current collection set.
975 size_t collection_set_size() { return _collection_set_size; }
977 // Add "hr" to the CS.
978 void add_to_collection_set(HeapRegion* hr);
980 bool should_initiate_conc_mark() { return _should_initiate_conc_mark; }
981 void set_should_initiate_conc_mark() { _should_initiate_conc_mark = true; }
982 void unset_should_initiate_conc_mark(){ _should_initiate_conc_mark = false; }
984 // If an expansion would be appropriate, because recent GC overhead had
985 // exceeded the desired limit, return an amount to expand by.
986 virtual size_t expansion_amount();
988 // note start of mark thread
989 void note_start_of_mark_thread();
991 // The marked bytes of the "r" has changed; reclassify it's desirability
992 // for marking. Also asserts that "r" is eligible for a CS.
993 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
995 #ifndef PRODUCT
996 // Check any appropriate marked bytes info, asserting false if
997 // something's wrong, else returning "true".
998 virtual bool assertMarkedBytesDataOK() = 0;
999 #endif
1001 // Print tracing information.
1002 void print_tracing_info() const;
1004 // Print stats on young survival ratio
1005 void print_yg_surv_rate_info() const;
1007 void finished_recalculating_age_indexes(bool is_survivors) {
1008 if (is_survivors) {
1009 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1010 } else {
1011 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1012 }
1013 // do that for any other surv rate groups
1014 }
1016 bool should_add_next_region_to_young_list();
1018 bool in_young_gc_mode() {
1019 return _in_young_gc_mode;
1020 }
1021 void set_in_young_gc_mode(bool in_young_gc_mode) {
1022 _in_young_gc_mode = in_young_gc_mode;
1023 }
1025 bool full_young_gcs() {
1026 return _full_young_gcs;
1027 }
1028 void set_full_young_gcs(bool full_young_gcs) {
1029 _full_young_gcs = full_young_gcs;
1030 }
1032 bool adaptive_young_list_length() {
1033 return _adaptive_young_list_length;
1034 }
1035 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1036 _adaptive_young_list_length = adaptive_young_list_length;
1037 }
1039 inline double get_gc_eff_factor() {
1040 double ratio = _known_garbage_ratio;
1042 double square = ratio * ratio;
1043 // square = square * square;
1044 double ret = square * 9.0 + 1.0;
1045 #if 0
1046 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1047 #endif // 0
1048 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1049 return ret;
1050 }
1052 //
1053 // Survivor regions policy.
1054 //
1055 protected:
1057 // Current tenuring threshold, set to 0 if the collector reaches the
1058 // maximum amount of suvivors regions.
1059 int _tenuring_threshold;
1061 // The limit on the number of regions allocated for survivors.
1062 size_t _max_survivor_regions;
1064 // The amount of survor regions after a collection.
1065 size_t _recorded_survivor_regions;
1066 // List of survivor regions.
1067 HeapRegion* _recorded_survivor_head;
1068 HeapRegion* _recorded_survivor_tail;
1070 ageTable _survivors_age_table;
1072 public:
1074 inline GCAllocPurpose
1075 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1076 if (age < _tenuring_threshold && src_region->is_young()) {
1077 return GCAllocForSurvived;
1078 } else {
1079 return GCAllocForTenured;
1080 }
1081 }
1083 inline bool track_object_age(GCAllocPurpose purpose) {
1084 return purpose == GCAllocForSurvived;
1085 }
1087 inline GCAllocPurpose alternative_purpose(int purpose) {
1088 return GCAllocForTenured;
1089 }
1091 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1093 size_t max_regions(int purpose);
1095 // The limit on regions for a particular purpose is reached.
1096 void note_alloc_region_limit_reached(int purpose) {
1097 if (purpose == GCAllocForSurvived) {
1098 _tenuring_threshold = 0;
1099 }
1100 }
1102 void note_start_adding_survivor_regions() {
1103 _survivor_surv_rate_group->start_adding_regions();
1104 }
1106 void note_stop_adding_survivor_regions() {
1107 _survivor_surv_rate_group->stop_adding_regions();
1108 }
1110 void record_survivor_regions(size_t regions,
1111 HeapRegion* head,
1112 HeapRegion* tail) {
1113 _recorded_survivor_regions = regions;
1114 _recorded_survivor_head = head;
1115 _recorded_survivor_tail = tail;
1116 }
1118 size_t recorded_survivor_regions() {
1119 return _recorded_survivor_regions;
1120 }
1122 void record_thread_age_table(ageTable* age_table)
1123 {
1124 _survivors_age_table.merge_par(age_table);
1125 }
1127 // Calculates survivor space parameters.
1128 void calculate_survivors_policy();
1130 };
1132 // This encapsulates a particular strategy for a g1 Collector.
1133 //
1134 // Start a concurrent mark when our heap size is n bytes
1135 // greater then our heap size was at the last concurrent
1136 // mark. Where n is a function of the CMSTriggerRatio
1137 // and the MinHeapFreeRatio.
1138 //
1139 // Start a g1 collection pause when we have allocated the
1140 // average number of bytes currently being freed in
1141 // a collection, but only if it is at least one region
1142 // full
1143 //
1144 // Resize Heap based on desired
1145 // allocation space, where desired allocation space is
1146 // a function of survival rate and desired future to size.
1147 //
1148 // Choose collection set by first picking all older regions
1149 // which have a survival rate which beats our projected young
1150 // survival rate. Then fill out the number of needed regions
1151 // with young regions.
1153 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1154 CollectionSetChooser* _collectionSetChooser;
1155 // If the estimated is less then desirable, resize if possible.
1156 void expand_if_possible(size_t numRegions);
1158 virtual void choose_collection_set();
1159 virtual void record_collection_pause_start(double start_time_sec,
1160 size_t start_used);
1161 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1162 size_t max_live_bytes);
1163 virtual void record_full_collection_end();
1165 public:
1166 G1CollectorPolicy_BestRegionsFirst() {
1167 _collectionSetChooser = new CollectionSetChooser();
1168 }
1169 void record_collection_pause_end(bool abandoned);
1170 bool should_do_collection_pause(size_t word_size);
1171 // This is not needed any more, after the CSet choosing code was
1172 // changed to use the pause prediction work. But let's leave the
1173 // hook in just in case.
1174 void note_change_in_marked_bytes(HeapRegion* r) { }
1175 #ifndef PRODUCT
1176 bool assertMarkedBytesDataOK();
1177 #endif
1178 };
1180 // This should move to some place more general...
1182 // If we have "n" measurements, and we've kept track of their "sum" and the
1183 // "sum_of_squares" of the measurements, this returns the variance of the
1184 // sequence.
1185 inline double variance(int n, double sum_of_squares, double sum) {
1186 double n_d = (double)n;
1187 double avg = sum/n_d;
1188 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1189 }
1191 // Local Variables: ***
1192 // c-indentation-style: gnu ***
1193 // End: ***