Fri, 14 Oct 2011 11:12:24 -0400
7088680: G1: Cleanup in the G1CollectorPolicy class
Summary: Removed unused fields and methods, removed the G1CollectoryPolicy_BestRegionsFirst class and folded its functionality into the G1CollectorPolicy class.
Reviewed-by: ysr, brutisso, jcoomes
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.
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
28 #include "gc_implementation/g1/collectionSetChooser.hpp"
29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 #include "memory/collectorPolicy.hpp"
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.
37 class HeapRegion;
38 class CollectionSetChooser;
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.
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 }
56 class MainBodySummary;
58 class PauseSummary: public CHeapObj {
59 define_num_seq(total)
60 define_num_seq(other)
62 public:
63 virtual MainBodySummary* main_body_summary() { return NULL; }
64 };
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 };
80 class Summary: public PauseSummary,
81 public MainBodySummary {
82 public:
83 virtual MainBodySummary* main_body_summary() { return this; }
84 };
86 class G1CollectorPolicy: public CollectorPolicy {
87 private:
88 // The number of pauses during the execution.
89 long _n_pauses;
91 // either equal to the number of parallel threads, if ParallelGCThreads
92 // has been set, or 1 otherwise
93 int _parallel_gc_threads;
95 enum SomePrivateConstants {
96 NumPrevPausesForHeuristics = 10
97 };
99 G1MMUTracker* _mmu_tracker;
101 void initialize_flags();
103 void initialize_all() {
104 initialize_flags();
105 initialize_size_info();
106 initialize_perm_generation(PermGen::MarkSweepCompact);
107 }
109 CollectionSetChooser* _collectionSetChooser;
111 double _cur_collection_start_sec;
112 size_t _cur_collection_pause_used_at_start_bytes;
113 size_t _cur_collection_pause_used_regions_at_start;
114 size_t _prev_collection_pause_used_at_end_bytes;
115 double _cur_collection_par_time_ms;
116 double _cur_satb_drain_time_ms;
117 double _cur_clear_ct_time_ms;
118 bool _satb_drain_time_set;
119 double _cur_ref_proc_time_ms;
120 double _cur_ref_enq_time_ms;
122 #ifndef PRODUCT
123 // Card Table Count Cache stats
124 double _min_clear_cc_time_ms; // min
125 double _max_clear_cc_time_ms; // max
126 double _cur_clear_cc_time_ms; // clearing time during current pause
127 double _cum_clear_cc_time_ms; // cummulative clearing time
128 jlong _num_cc_clears; // number of times the card count cache has been cleared
129 #endif
131 // Statistics for recent GC pauses. See below for how indexed.
132 TruncatedSeq* _recent_rs_scan_times_ms;
134 // These exclude marking times.
135 TruncatedSeq* _recent_pause_times_ms;
136 TruncatedSeq* _recent_gc_times_ms;
138 TruncatedSeq* _recent_CS_bytes_used_before;
139 TruncatedSeq* _recent_CS_bytes_surviving;
141 TruncatedSeq* _recent_rs_sizes;
143 TruncatedSeq* _concurrent_mark_remark_times_ms;
144 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
146 Summary* _summary;
148 NumberSeq* _all_pause_times_ms;
149 NumberSeq* _all_full_gc_times_ms;
150 double _stop_world_start;
151 NumberSeq* _all_stop_world_times_ms;
152 NumberSeq* _all_yield_times_ms;
154 size_t _region_num_young;
155 size_t _region_num_tenured;
156 size_t _prev_region_num_young;
157 size_t _prev_region_num_tenured;
159 NumberSeq* _all_mod_union_times_ms;
161 int _aux_num;
162 NumberSeq* _all_aux_times_ms;
163 double* _cur_aux_start_times_ms;
164 double* _cur_aux_times_ms;
165 bool* _cur_aux_times_set;
167 double* _par_last_gc_worker_start_times_ms;
168 double* _par_last_ext_root_scan_times_ms;
169 double* _par_last_mark_stack_scan_times_ms;
170 double* _par_last_update_rs_times_ms;
171 double* _par_last_update_rs_processed_buffers;
172 double* _par_last_scan_rs_times_ms;
173 double* _par_last_obj_copy_times_ms;
174 double* _par_last_termination_times_ms;
175 double* _par_last_termination_attempts;
176 double* _par_last_gc_worker_end_times_ms;
177 double* _par_last_gc_worker_times_ms;
179 // indicates whether we are in full young or partially young GC mode
180 bool _full_young_gcs;
182 // if true, then it tries to dynamically adjust the length of the
183 // young list
184 bool _adaptive_young_list_length;
185 size_t _young_list_target_length;
186 size_t _young_list_fixed_length;
187 size_t _prev_eden_capacity; // used for logging
189 // The max number of regions we can extend the eden by while the GC
190 // locker is active. This should be >= _young_list_target_length;
191 size_t _young_list_max_length;
193 size_t _young_cset_length;
194 bool _last_young_gc_full;
196 unsigned _full_young_pause_num;
197 unsigned _partial_young_pause_num;
199 bool _during_marking;
200 bool _in_marking_window;
201 bool _in_marking_window_im;
203 SurvRateGroup* _short_lived_surv_rate_group;
204 SurvRateGroup* _survivor_surv_rate_group;
205 // add here any more surv rate groups
207 double _gc_overhead_perc;
209 double _reserve_factor;
210 size_t _reserve_regions;
212 bool during_marking() {
213 return _during_marking;
214 }
216 // <NEW PREDICTION>
218 private:
219 enum PredictionConstants {
220 TruncatedSeqLength = 10
221 };
223 TruncatedSeq* _alloc_rate_ms_seq;
224 double _prev_collection_pause_end_ms;
226 TruncatedSeq* _pending_card_diff_seq;
227 TruncatedSeq* _rs_length_diff_seq;
228 TruncatedSeq* _cost_per_card_ms_seq;
229 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
230 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
231 TruncatedSeq* _cost_per_entry_ms_seq;
232 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
233 TruncatedSeq* _cost_per_byte_ms_seq;
234 TruncatedSeq* _constant_other_time_ms_seq;
235 TruncatedSeq* _young_other_cost_per_region_ms_seq;
236 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
238 TruncatedSeq* _pending_cards_seq;
239 TruncatedSeq* _scanned_cards_seq;
240 TruncatedSeq* _rs_lengths_seq;
242 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
244 TruncatedSeq* _young_gc_eff_seq;
246 TruncatedSeq* _max_conc_overhead_seq;
248 bool _using_new_ratio_calculations;
249 size_t _min_desired_young_length; // as set on the command line or default calculations
250 size_t _max_desired_young_length; // as set on the command line or default calculations
252 size_t _recorded_young_regions;
253 size_t _recorded_non_young_regions;
254 size_t _recorded_region_num;
256 size_t _free_regions_at_end_of_collection;
258 size_t _recorded_rs_lengths;
259 size_t _max_rs_lengths;
261 size_t _recorded_marked_bytes;
262 size_t _recorded_young_bytes;
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;
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;
278 double _vtime_diff_ms;
280 double _recorded_young_free_cset_time_ms;
281 double _recorded_non_young_free_cset_time_ms;
283 double _sigma;
284 double _expensive_region_limit_ms;
286 size_t _rs_lengths_prediction;
288 size_t _known_garbage_bytes;
289 double _known_garbage_ratio;
291 double sigma() {
292 return _sigma;
293 }
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 }
304 double get_new_neg_prediction(TruncatedSeq* seq) {
305 return seq->davg() - sigma() * seq->dsd();
306 }
308 #ifndef PRODUCT
309 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
310 #endif // PRODUCT
312 void adjust_concurrent_refinement(double update_rs_time,
313 double update_rs_processed_buffers,
314 double goal_ms);
316 double _pause_time_target_ms;
317 double _recorded_young_cset_choice_time_ms;
318 double _recorded_non_young_cset_choice_time_ms;
319 bool _within_target;
320 size_t _pending_cards;
321 size_t _max_pending_cards;
323 public:
325 void set_region_short_lived(HeapRegion* hr) {
326 hr->install_surv_rate_group(_short_lived_surv_rate_group);
327 }
329 void set_region_survivors(HeapRegion* hr) {
330 hr->install_surv_rate_group(_survivor_surv_rate_group);
331 }
333 #ifndef PRODUCT
334 bool verify_young_ages();
335 #endif // PRODUCT
337 double get_new_prediction(TruncatedSeq* seq) {
338 return MAX2(seq->davg() + sigma() * seq->dsd(),
339 seq->davg() * confidence_factor(seq->num()));
340 }
342 size_t young_cset_length() {
343 return _young_cset_length;
344 }
346 void record_max_rs_lengths(size_t rs_lengths) {
347 _max_rs_lengths = rs_lengths;
348 }
350 size_t predict_pending_card_diff() {
351 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
352 if (prediction < 0.00001)
353 return 0;
354 else
355 return (size_t) prediction;
356 }
358 size_t predict_pending_cards() {
359 size_t max_pending_card_num = _g1->max_pending_card_num();
360 size_t diff = predict_pending_card_diff();
361 size_t prediction;
362 if (diff > max_pending_card_num)
363 prediction = max_pending_card_num;
364 else
365 prediction = max_pending_card_num - diff;
367 return prediction;
368 }
370 size_t predict_rs_length_diff() {
371 return (size_t) get_new_prediction(_rs_length_diff_seq);
372 }
374 double predict_alloc_rate_ms() {
375 return get_new_prediction(_alloc_rate_ms_seq);
376 }
378 double predict_cost_per_card_ms() {
379 return get_new_prediction(_cost_per_card_ms_seq);
380 }
382 double predict_rs_update_time_ms(size_t pending_cards) {
383 return (double) pending_cards * predict_cost_per_card_ms();
384 }
386 double predict_fully_young_cards_per_entry_ratio() {
387 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
388 }
390 double predict_partially_young_cards_per_entry_ratio() {
391 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
392 return predict_fully_young_cards_per_entry_ratio();
393 else
394 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
395 }
397 size_t predict_young_card_num(size_t rs_length) {
398 return (size_t) ((double) rs_length *
399 predict_fully_young_cards_per_entry_ratio());
400 }
402 size_t predict_non_young_card_num(size_t rs_length) {
403 return (size_t) ((double) rs_length *
404 predict_partially_young_cards_per_entry_ratio());
405 }
407 double predict_rs_scan_time_ms(size_t card_num) {
408 if (full_young_gcs())
409 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
410 else
411 return predict_partially_young_rs_scan_time_ms(card_num);
412 }
414 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
415 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
416 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
417 else
418 return (double) card_num *
419 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
420 }
422 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
423 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
424 return 1.1 * (double) bytes_to_copy *
425 get_new_prediction(_cost_per_byte_ms_seq);
426 else
427 return (double) bytes_to_copy *
428 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
429 }
431 double predict_object_copy_time_ms(size_t bytes_to_copy) {
432 if (_in_marking_window && !_in_marking_window_im)
433 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
434 else
435 return (double) bytes_to_copy *
436 get_new_prediction(_cost_per_byte_ms_seq);
437 }
439 double predict_constant_other_time_ms() {
440 return get_new_prediction(_constant_other_time_ms_seq);
441 }
443 double predict_young_other_time_ms(size_t young_num) {
444 return
445 (double) young_num *
446 get_new_prediction(_young_other_cost_per_region_ms_seq);
447 }
449 double predict_non_young_other_time_ms(size_t non_young_num) {
450 return
451 (double) non_young_num *
452 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
453 }
455 void check_if_region_is_too_expensive(double predicted_time_ms);
457 double predict_young_collection_elapsed_time_ms(size_t adjustment);
458 double predict_base_elapsed_time_ms(size_t pending_cards);
459 double predict_base_elapsed_time_ms(size_t pending_cards,
460 size_t scanned_cards);
461 size_t predict_bytes_to_copy(HeapRegion* hr);
462 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
464 void start_recording_regions();
465 void record_cset_region_info(HeapRegion* hr, bool young);
466 void record_non_young_cset_region(HeapRegion* hr);
468 void set_recorded_young_regions(size_t n_regions);
469 void set_recorded_young_bytes(size_t bytes);
470 void set_recorded_rs_lengths(size_t rs_lengths);
471 void set_predicted_bytes_to_copy(size_t bytes);
473 void end_recording_regions();
475 void record_vtime_diff_ms(double vtime_diff_ms) {
476 _vtime_diff_ms = vtime_diff_ms;
477 }
479 void record_young_free_cset_time_ms(double time_ms) {
480 _recorded_young_free_cset_time_ms = time_ms;
481 }
483 void record_non_young_free_cset_time_ms(double time_ms) {
484 _recorded_non_young_free_cset_time_ms = time_ms;
485 }
487 double predict_young_gc_eff() {
488 return get_new_neg_prediction(_young_gc_eff_seq);
489 }
491 double predict_survivor_regions_evac_time();
493 // </NEW PREDICTION>
495 void cset_regions_freed() {
496 bool propagate = _last_young_gc_full && !_in_marking_window;
497 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
498 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
499 // also call it on any more surv rate groups
500 }
502 void set_known_garbage_bytes(size_t known_garbage_bytes) {
503 _known_garbage_bytes = known_garbage_bytes;
504 size_t heap_bytes = _g1->capacity();
505 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
506 }
508 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
509 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
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 }
516 G1MMUTracker* mmu_tracker() {
517 return _mmu_tracker;
518 }
520 double max_pause_time_ms() {
521 return _mmu_tracker->max_gc_time() * 1000.0;
522 }
524 double predict_remark_time_ms() {
525 return get_new_prediction(_concurrent_mark_remark_times_ms);
526 }
528 double predict_cleanup_time_ms() {
529 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
530 }
532 // Returns an estimate of the survival rate of the region at yg-age
533 // "yg_age".
534 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
535 TruncatedSeq* seq = surv_rate_group->get_seq(age);
536 if (seq->num() == 0)
537 gclog_or_tty->print("BARF! age is %d", age);
538 guarantee( seq->num() > 0, "invariant" );
539 double pred = get_new_prediction(seq);
540 if (pred > 1.0)
541 pred = 1.0;
542 return pred;
543 }
545 double predict_yg_surv_rate(int age) {
546 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
547 }
549 double accum_yg_surv_rate_pred(int age) {
550 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
551 }
553 private:
554 void print_stats(int level, const char* str, double value);
555 void print_stats(int level, const char* str, int value);
557 void print_par_stats(int level, const char* str, double* data);
558 void print_par_sizes(int level, const char* str, double* data);
560 void check_other_times(int level,
561 NumberSeq* other_times_ms,
562 NumberSeq* calc_other_times_ms) const;
564 void print_summary (PauseSummary* stats) const;
566 void print_summary (int level, const char* str, NumberSeq* seq) const;
567 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
569 double avg_value (double* data);
570 double max_value (double* data);
571 double sum_of_values (double* data);
572 double max_sum (double* data1, double* data2);
574 int _last_satb_drain_processed_buffers;
575 int _last_update_rs_processed_buffers;
576 double _last_pause_time_ms;
578 size_t _bytes_in_collection_set_before_gc;
579 size_t _bytes_copied_during_gc;
581 // Used to count used bytes in CS.
582 friend class CountCSClosure;
584 // Statistics kept per GC stoppage, pause or full.
585 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
587 // Add a new GC of the given duration and end time to the record.
588 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
590 // The head of the list (via "next_in_collection_set()") representing the
591 // current collection set. Set from the incrementally built collection
592 // set at the start of the pause.
593 HeapRegion* _collection_set;
595 // The number of regions in the collection set. Set from the incrementally
596 // built collection set at the start of an evacuation pause.
597 size_t _collection_set_size;
599 // The number of bytes in the collection set before the pause. Set from
600 // the incrementally built collection set at the start of an evacuation
601 // pause.
602 size_t _collection_set_bytes_used_before;
604 // The associated information that is maintained while the incremental
605 // collection set is being built with young regions. Used to populate
606 // the recorded info for the evacuation pause.
608 enum CSetBuildType {
609 Active, // We are actively building the collection set
610 Inactive // We are not actively building the collection set
611 };
613 CSetBuildType _inc_cset_build_state;
615 // The head of the incrementally built collection set.
616 HeapRegion* _inc_cset_head;
618 // The tail of the incrementally built collection set.
619 HeapRegion* _inc_cset_tail;
621 // The number of regions in the incrementally built collection set.
622 // Used to set _collection_set_size at the start of an evacuation
623 // pause.
624 size_t _inc_cset_size;
626 // Used as the index in the surving young words structure
627 // which tracks the amount of space, for each young region,
628 // that survives the pause.
629 size_t _inc_cset_young_index;
631 // The number of bytes in the incrementally built collection set.
632 // Used to set _collection_set_bytes_used_before at the start of
633 // an evacuation pause.
634 size_t _inc_cset_bytes_used_before;
636 // Used to record the highest end of heap region in collection set
637 HeapWord* _inc_cset_max_finger;
639 // The number of recorded used bytes in the young regions
640 // of the collection set. This is the sum of the used() bytes
641 // of retired young regions in the collection set.
642 size_t _inc_cset_recorded_young_bytes;
644 // The RSet lengths recorded for regions in the collection set
645 // (updated by the periodic sampling of the regions in the
646 // young list/collection set).
647 size_t _inc_cset_recorded_rs_lengths;
649 // The predicted elapsed time it will take to collect the regions
650 // in the collection set (updated by the periodic sampling of the
651 // regions in the young list/collection set).
652 double _inc_cset_predicted_elapsed_time_ms;
654 // The predicted bytes to copy for the regions in the collection
655 // set (updated by the periodic sampling of the regions in the
656 // young list/collection set).
657 size_t _inc_cset_predicted_bytes_to_copy;
659 // Stash a pointer to the g1 heap.
660 G1CollectedHeap* _g1;
662 // The average time in ms per collection pause, averaged over recent pauses.
663 double recent_avg_time_for_pauses_ms();
665 // The average time in ms for RS scanning, per pause, averaged
666 // over recent pauses. (Note the RS scanning time for a pause
667 // is itself an average of the RS scanning time for each worker
668 // thread.)
669 double recent_avg_time_for_rs_scan_ms();
671 // The number of "recent" GCs recorded in the number sequences
672 int number_of_recent_gcs();
674 // The average survival ratio, computed by the total number of bytes
675 // suriviving / total number of bytes before collection over the last
676 // several recent pauses.
677 double recent_avg_survival_fraction();
678 // The survival fraction of the most recent pause; if there have been no
679 // pauses, returns 1.0.
680 double last_survival_fraction();
682 // Returns a "conservative" estimate of the recent survival rate, i.e.,
683 // one that may be higher than "recent_avg_survival_fraction".
684 // This is conservative in several ways:
685 // If there have been few pauses, it will assume a potential high
686 // variance, and err on the side of caution.
687 // It puts a lower bound (currently 0.1) on the value it will return.
688 // To try to detect phase changes, if the most recent pause ("latest") has a
689 // higher-than average ("avg") survival rate, it returns that rate.
690 // "work" version is a utility function; young is restricted to young regions.
691 double conservative_avg_survival_fraction_work(double avg,
692 double latest);
694 // The arguments are the two sequences that keep track of the number of bytes
695 // surviving and the total number of bytes before collection, resp.,
696 // over the last evereal recent pauses
697 // Returns the survival rate for the category in the most recent pause.
698 // If there have been no pauses, returns 1.0.
699 double last_survival_fraction_work(TruncatedSeq* surviving,
700 TruncatedSeq* before);
702 // The arguments are the two sequences that keep track of the number of bytes
703 // surviving and the total number of bytes before collection, resp.,
704 // over the last several recent pauses
705 // Returns the average survival ration over the last several recent pauses
706 // If there have been no pauses, return 1.0
707 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
708 TruncatedSeq* before);
710 double conservative_avg_survival_fraction() {
711 double avg = recent_avg_survival_fraction();
712 double latest = last_survival_fraction();
713 return conservative_avg_survival_fraction_work(avg, latest);
714 }
716 // The ratio of gc time to elapsed time, computed over recent pauses.
717 double _recent_avg_pause_time_ratio;
719 double recent_avg_pause_time_ratio() {
720 return _recent_avg_pause_time_ratio;
721 }
723 // Number of pauses between concurrent marking.
724 size_t _pauses_btwn_concurrent_mark;
726 // At the end of a pause we check the heap occupancy and we decide
727 // whether we will start a marking cycle during the next pause. If
728 // we decide that we want to do that, we will set this parameter to
729 // true. So, this parameter will stay true between the end of a
730 // pause and the beginning of a subsequent pause (not necessarily
731 // the next one, see the comments on the next field) when we decide
732 // that we will indeed start a marking cycle and do the initial-mark
733 // work.
734 volatile bool _initiate_conc_mark_if_possible;
736 // If initiate_conc_mark_if_possible() is set at the beginning of a
737 // pause, it is a suggestion that the pause should start a marking
738 // cycle by doing the initial-mark work. However, it is possible
739 // that the concurrent marking thread is still finishing up the
740 // previous marking cycle (e.g., clearing the next marking
741 // bitmap). If that is the case we cannot start a new cycle and
742 // we'll have to wait for the concurrent marking thread to finish
743 // what it is doing. In this case we will postpone the marking cycle
744 // initiation decision for the next pause. When we eventually decide
745 // to start a cycle, we will set _during_initial_mark_pause which
746 // will stay true until the end of the initial-mark pause and it's
747 // the condition that indicates that a pause is doing the
748 // initial-mark work.
749 volatile bool _during_initial_mark_pause;
751 bool _should_revert_to_full_young_gcs;
752 bool _last_full_young_gc;
754 // This set of variables tracks the collector efficiency, in order to
755 // determine whether we should initiate a new marking.
756 double _cur_mark_stop_world_time_ms;
757 double _mark_remark_start_sec;
758 double _mark_cleanup_start_sec;
759 double _mark_closure_time_ms;
761 // Update the young list target length either by setting it to the
762 // desired fixed value or by calculating it using G1's pause
763 // prediction model. If no rs_lengths parameter is passed, predict
764 // the RS lengths using the prediction model, otherwise use the
765 // given rs_lengths as the prediction.
766 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
768 // Calculate and return the minimum desired young list target
769 // length. This is the minimum desired young list length according
770 // to the user's inputs.
771 size_t calculate_young_list_desired_min_length(size_t base_min_length);
773 // Calculate and return the maximum desired young list target
774 // length. This is the maximum desired young list length according
775 // to the user's inputs.
776 size_t calculate_young_list_desired_max_length();
778 // Calculate and return the maximum young list target length that
779 // can fit into the pause time goal. The parameters are: rs_lengths
780 // represent the prediction of how large the young RSet lengths will
781 // be, base_min_length is the alreay existing number of regions in
782 // the young list, min_length and max_length are the desired min and
783 // max young list length according to the user's inputs.
784 size_t calculate_young_list_target_length(size_t rs_lengths,
785 size_t base_min_length,
786 size_t desired_min_length,
787 size_t desired_max_length);
789 // Check whether a given young length (young_length) fits into the
790 // given target pause time and whether the prediction for the amount
791 // of objects to be copied for the given length will fit into the
792 // given free space (expressed by base_free_regions). It is used by
793 // calculate_young_list_target_length().
794 bool predict_will_fit(size_t young_length, double base_time_ms,
795 size_t base_free_regions, double target_pause_time_ms);
797 // Count the number of bytes used in the CS.
798 void count_CS_bytes_used();
800 void update_young_list_size_using_newratio(size_t number_of_heap_regions);
802 public:
804 G1CollectorPolicy();
806 virtual G1CollectorPolicy* as_g1_policy() { return this; }
808 virtual CollectorPolicy::Name kind() {
809 return CollectorPolicy::G1CollectorPolicyKind;
810 }
812 // Check the current value of the young list RSet lengths and
813 // compare it against the last prediction. If the current value is
814 // higher, recalculate the young list target length prediction.
815 void revise_young_list_target_length_if_necessary();
817 size_t bytes_in_collection_set() {
818 return _bytes_in_collection_set_before_gc;
819 }
821 unsigned calc_gc_alloc_time_stamp() {
822 return _all_pause_times_ms->num() + 1;
823 }
825 // This should be called after the heap is resized.
826 void record_new_heap_size(size_t new_number_of_regions);
828 public:
830 void init();
832 // Create jstat counters for the policy.
833 virtual void initialize_gc_policy_counters();
835 virtual HeapWord* mem_allocate_work(size_t size,
836 bool is_tlab,
837 bool* gc_overhead_limit_was_exceeded);
839 // This method controls how a collector handles one or more
840 // of its generations being fully allocated.
841 virtual HeapWord* satisfy_failed_allocation(size_t size,
842 bool is_tlab);
844 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
846 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
848 // The number of collection pauses so far.
849 long n_pauses() const { return _n_pauses; }
851 // Update the heuristic info to record a collection pause of the given
852 // start time, where the given number of bytes were used at the start.
853 // This may involve changing the desired size of a collection set.
855 void record_stop_world_start();
857 void record_collection_pause_start(double start_time_sec, size_t start_used);
859 // Must currently be called while the world is stopped.
860 void record_concurrent_mark_init_end(double
861 mark_init_elapsed_time_ms);
863 void record_mark_closure_time(double mark_closure_time_ms);
865 void record_concurrent_mark_remark_start();
866 void record_concurrent_mark_remark_end();
868 void record_concurrent_mark_cleanup_start();
869 void record_concurrent_mark_cleanup_end();
870 void record_concurrent_mark_cleanup_completed();
872 void record_concurrent_pause();
873 void record_concurrent_pause_end();
875 void record_collection_pause_end();
876 void print_heap_transition();
878 // Record the fact that a full collection occurred.
879 void record_full_collection_start();
880 void record_full_collection_end();
882 void record_gc_worker_start_time(int worker_i, double ms) {
883 _par_last_gc_worker_start_times_ms[worker_i] = ms;
884 }
886 void record_ext_root_scan_time(int worker_i, double ms) {
887 _par_last_ext_root_scan_times_ms[worker_i] = ms;
888 }
890 void record_mark_stack_scan_time(int worker_i, double ms) {
891 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
892 }
894 void record_satb_drain_time(double ms) {
895 _cur_satb_drain_time_ms = ms;
896 _satb_drain_time_set = true;
897 }
899 void record_satb_drain_processed_buffers (int processed_buffers) {
900 _last_satb_drain_processed_buffers = processed_buffers;
901 }
903 void record_mod_union_time(double ms) {
904 _all_mod_union_times_ms->add(ms);
905 }
907 void record_update_rs_time(int thread, double ms) {
908 _par_last_update_rs_times_ms[thread] = ms;
909 }
911 void record_update_rs_processed_buffers (int thread,
912 double processed_buffers) {
913 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
914 }
916 void record_scan_rs_time(int thread, double ms) {
917 _par_last_scan_rs_times_ms[thread] = ms;
918 }
920 void reset_obj_copy_time(int thread) {
921 _par_last_obj_copy_times_ms[thread] = 0.0;
922 }
924 void reset_obj_copy_time() {
925 reset_obj_copy_time(0);
926 }
928 void record_obj_copy_time(int thread, double ms) {
929 _par_last_obj_copy_times_ms[thread] += ms;
930 }
932 void record_termination(int thread, double ms, size_t attempts) {
933 _par_last_termination_times_ms[thread] = ms;
934 _par_last_termination_attempts[thread] = (double) attempts;
935 }
937 void record_gc_worker_end_time(int worker_i, double ms) {
938 _par_last_gc_worker_end_times_ms[worker_i] = ms;
939 }
941 void record_pause_time_ms(double ms) {
942 _last_pause_time_ms = ms;
943 }
945 void record_clear_ct_time(double ms) {
946 _cur_clear_ct_time_ms = ms;
947 }
949 void record_par_time(double ms) {
950 _cur_collection_par_time_ms = ms;
951 }
953 void record_aux_start_time(int i) {
954 guarantee(i < _aux_num, "should be within range");
955 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
956 }
958 void record_aux_end_time(int i) {
959 guarantee(i < _aux_num, "should be within range");
960 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
961 _cur_aux_times_set[i] = true;
962 _cur_aux_times_ms[i] += ms;
963 }
965 void record_ref_proc_time(double ms) {
966 _cur_ref_proc_time_ms = ms;
967 }
969 void record_ref_enq_time(double ms) {
970 _cur_ref_enq_time_ms = ms;
971 }
973 #ifndef PRODUCT
974 void record_cc_clear_time(double ms) {
975 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
976 _min_clear_cc_time_ms = ms;
977 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
978 _max_clear_cc_time_ms = ms;
979 _cur_clear_cc_time_ms = ms;
980 _cum_clear_cc_time_ms += ms;
981 _num_cc_clears++;
982 }
983 #endif
985 // Record how much space we copied during a GC. This is typically
986 // called when a GC alloc region is being retired.
987 void record_bytes_copied_during_gc(size_t bytes) {
988 _bytes_copied_during_gc += bytes;
989 }
991 // The amount of space we copied during a GC.
992 size_t bytes_copied_during_gc() {
993 return _bytes_copied_during_gc;
994 }
996 // Choose a new collection set. Marks the chosen regions as being
997 // "in_collection_set", and links them together. The head and number of
998 // the collection set are available via access methods.
999 void choose_collection_set(double target_pause_time_ms);
1001 // The head of the list (via "next_in_collection_set()") representing the
1002 // current collection set.
1003 HeapRegion* collection_set() { return _collection_set; }
1005 void clear_collection_set() { _collection_set = NULL; }
1007 // The number of elements in the current collection set.
1008 size_t collection_set_size() { return _collection_set_size; }
1010 // Add "hr" to the CS.
1011 void add_to_collection_set(HeapRegion* hr);
1013 // Incremental CSet Support
1015 // The head of the incrementally built collection set.
1016 HeapRegion* inc_cset_head() { return _inc_cset_head; }
1018 // The tail of the incrementally built collection set.
1019 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
1021 // The number of elements in the incrementally built collection set.
1022 size_t inc_cset_size() { return _inc_cset_size; }
1024 // Initialize incremental collection set info.
1025 void start_incremental_cset_building();
1027 void clear_incremental_cset() {
1028 _inc_cset_head = NULL;
1029 _inc_cset_tail = NULL;
1030 }
1032 // Stop adding regions to the incremental collection set
1033 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
1035 // Add/remove information about hr to the aggregated information
1036 // for the incrementally built collection set.
1037 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
1038 void remove_from_incremental_cset_info(HeapRegion* hr);
1040 // Update information about hr in the aggregated information for
1041 // the incrementally built collection set.
1042 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
1044 private:
1045 // Update the incremental cset information when adding a region
1046 // (should not be called directly).
1047 void add_region_to_incremental_cset_common(HeapRegion* hr);
1049 public:
1050 // Add hr to the LHS of the incremental collection set.
1051 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1053 // Add hr to the RHS of the incremental collection set.
1054 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1056 #ifndef PRODUCT
1057 void print_collection_set(HeapRegion* list_head, outputStream* st);
1058 #endif // !PRODUCT
1060 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1061 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1062 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1064 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1065 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1066 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1068 // This sets the initiate_conc_mark_if_possible() flag to start a
1069 // new cycle, as long as we are not already in one. It's best if it
1070 // is called during a safepoint when the test whether a cycle is in
1071 // progress or not is stable.
1072 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
1074 // This is called at the very beginning of an evacuation pause (it
1075 // has to be the first thing that the pause does). If
1076 // initiate_conc_mark_if_possible() is true, and the concurrent
1077 // marking thread has completed its work during the previous cycle,
1078 // it will set during_initial_mark_pause() to so that the pause does
1079 // the initial-mark work and start a marking cycle.
1080 void decide_on_conc_mark_initiation();
1082 // If an expansion would be appropriate, because recent GC overhead had
1083 // exceeded the desired limit, return an amount to expand by.
1084 size_t expansion_amount();
1086 #ifndef PRODUCT
1087 // Check any appropriate marked bytes info, asserting false if
1088 // something's wrong, else returning "true".
1089 bool assertMarkedBytesDataOK();
1090 #endif
1092 // Print tracing information.
1093 void print_tracing_info() const;
1095 // Print stats on young survival ratio
1096 void print_yg_surv_rate_info() const;
1098 void finished_recalculating_age_indexes(bool is_survivors) {
1099 if (is_survivors) {
1100 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1101 } else {
1102 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1103 }
1104 // do that for any other surv rate groups
1105 }
1107 bool is_young_list_full() {
1108 size_t young_list_length = _g1->young_list()->length();
1109 size_t young_list_target_length = _young_list_target_length;
1110 return young_list_length >= young_list_target_length;
1111 }
1113 bool can_expand_young_list() {
1114 size_t young_list_length = _g1->young_list()->length();
1115 size_t young_list_max_length = _young_list_max_length;
1116 return young_list_length < young_list_max_length;
1117 }
1119 size_t young_list_max_length() {
1120 return _young_list_max_length;
1121 }
1123 void update_region_num(bool young);
1125 bool full_young_gcs() {
1126 return _full_young_gcs;
1127 }
1128 void set_full_young_gcs(bool full_young_gcs) {
1129 _full_young_gcs = full_young_gcs;
1130 }
1132 bool adaptive_young_list_length() {
1133 return _adaptive_young_list_length;
1134 }
1135 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1136 _adaptive_young_list_length = adaptive_young_list_length;
1137 }
1139 inline double get_gc_eff_factor() {
1140 double ratio = _known_garbage_ratio;
1142 double square = ratio * ratio;
1143 // square = square * square;
1144 double ret = square * 9.0 + 1.0;
1145 #if 0
1146 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1147 #endif // 0
1148 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1149 return ret;
1150 }
1152 private:
1153 //
1154 // Survivor regions policy.
1155 //
1157 // Current tenuring threshold, set to 0 if the collector reaches the
1158 // maximum amount of suvivors regions.
1159 int _tenuring_threshold;
1161 // The limit on the number of regions allocated for survivors.
1162 size_t _max_survivor_regions;
1164 // For reporting purposes.
1165 size_t _eden_bytes_before_gc;
1166 size_t _survivor_bytes_before_gc;
1167 size_t _capacity_before_gc;
1169 // The amount of survor regions after a collection.
1170 size_t _recorded_survivor_regions;
1171 // List of survivor regions.
1172 HeapRegion* _recorded_survivor_head;
1173 HeapRegion* _recorded_survivor_tail;
1175 ageTable _survivors_age_table;
1177 public:
1179 inline GCAllocPurpose
1180 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1181 if (age < _tenuring_threshold && src_region->is_young()) {
1182 return GCAllocForSurvived;
1183 } else {
1184 return GCAllocForTenured;
1185 }
1186 }
1188 inline bool track_object_age(GCAllocPurpose purpose) {
1189 return purpose == GCAllocForSurvived;
1190 }
1192 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1194 size_t max_regions(int purpose);
1196 // The limit on regions for a particular purpose is reached.
1197 void note_alloc_region_limit_reached(int purpose) {
1198 if (purpose == GCAllocForSurvived) {
1199 _tenuring_threshold = 0;
1200 }
1201 }
1203 void note_start_adding_survivor_regions() {
1204 _survivor_surv_rate_group->start_adding_regions();
1205 }
1207 void note_stop_adding_survivor_regions() {
1208 _survivor_surv_rate_group->stop_adding_regions();
1209 }
1211 void record_survivor_regions(size_t regions,
1212 HeapRegion* head,
1213 HeapRegion* tail) {
1214 _recorded_survivor_regions = regions;
1215 _recorded_survivor_head = head;
1216 _recorded_survivor_tail = tail;
1217 }
1219 size_t recorded_survivor_regions() {
1220 return _recorded_survivor_regions;
1221 }
1223 void record_thread_age_table(ageTable* age_table)
1224 {
1225 _survivors_age_table.merge_par(age_table);
1226 }
1228 void update_max_gc_locker_expansion();
1230 // Calculates survivor space parameters.
1231 void update_survivors_policy();
1233 };
1235 // This should move to some place more general...
1237 // If we have "n" measurements, and we've kept track of their "sum" and the
1238 // "sum_of_squares" of the measurements, this returns the variance of the
1239 // sequence.
1240 inline double variance(int n, double sum_of_squares, double sum) {
1241 double n_d = (double)n;
1242 double avg = sum/n_d;
1243 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1244 }
1246 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP