Thu, 27 May 2010 19:08:38 -0700
6941466: Oracle rebranding changes for Hotspot repositories
Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair
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 */
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(update_rs)
65 define_num_seq(scan_rs)
66 define_num_seq(scan_new_refs) // Only for temp use; added to
67 // in parallel case.
68 define_num_seq(obj_copy)
69 define_num_seq(termination) // parallel only
70 define_num_seq(parallel_other) // parallel only
71 define_num_seq(mark_closure)
72 define_num_seq(clear_ct) // parallel only
73 };
75 class Summary: public PauseSummary,
76 public MainBodySummary {
77 public:
78 virtual MainBodySummary* main_body_summary() { return this; }
79 };
81 class AbandonedSummary: public PauseSummary {
82 };
84 class G1CollectorPolicy: public CollectorPolicy {
85 protected:
86 // The number of pauses during the execution.
87 long _n_pauses;
89 // either equal to the number of parallel threads, if ParallelGCThreads
90 // has been set, or 1 otherwise
91 int _parallel_gc_threads;
93 enum SomePrivateConstants {
94 NumPrevPausesForHeuristics = 10
95 };
97 G1MMUTracker* _mmu_tracker;
99 void initialize_flags();
101 void initialize_all() {
102 initialize_flags();
103 initialize_size_info();
104 initialize_perm_generation(PermGen::MarkSweepCompact);
105 }
107 virtual size_t default_init_heap_size() {
108 // Pick some reasonable default.
109 return 8*M;
110 }
112 double _cur_collection_start_sec;
113 size_t _cur_collection_pause_used_at_start_bytes;
114 size_t _cur_collection_pause_used_regions_at_start;
115 size_t _prev_collection_pause_used_at_end_bytes;
116 double _cur_collection_par_time_ms;
117 double _cur_satb_drain_time_ms;
118 double _cur_clear_ct_time_ms;
119 bool _satb_drain_time_set;
121 #ifndef PRODUCT
122 // Card Table Count Cache stats
123 double _min_clear_cc_time_ms; // min
124 double _max_clear_cc_time_ms; // max
125 double _cur_clear_cc_time_ms; // clearing time during current pause
126 double _cum_clear_cc_time_ms; // cummulative clearing time
127 jlong _num_cc_clears; // number of times the card count cache has been cleared
128 #endif
130 double _cur_CH_strong_roots_end_sec;
131 double _cur_CH_strong_roots_dur_ms;
132 double _cur_G1_strong_roots_end_sec;
133 double _cur_G1_strong_roots_dur_ms;
135 // Statistics for recent GC pauses. See below for how indexed.
136 TruncatedSeq* _recent_CH_strong_roots_times_ms;
137 TruncatedSeq* _recent_G1_strong_roots_times_ms;
138 TruncatedSeq* _recent_evac_times_ms;
139 // These exclude marking times.
140 TruncatedSeq* _recent_pause_times_ms;
141 TruncatedSeq* _recent_gc_times_ms;
143 TruncatedSeq* _recent_CS_bytes_used_before;
144 TruncatedSeq* _recent_CS_bytes_surviving;
146 TruncatedSeq* _recent_rs_sizes;
148 TruncatedSeq* _concurrent_mark_init_times_ms;
149 TruncatedSeq* _concurrent_mark_remark_times_ms;
150 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
152 Summary* _summary;
153 AbandonedSummary* _abandoned_summary;
155 NumberSeq* _all_pause_times_ms;
156 NumberSeq* _all_full_gc_times_ms;
157 double _stop_world_start;
158 NumberSeq* _all_stop_world_times_ms;
159 NumberSeq* _all_yield_times_ms;
161 size_t _region_num_young;
162 size_t _region_num_tenured;
163 size_t _prev_region_num_young;
164 size_t _prev_region_num_tenured;
166 NumberSeq* _all_mod_union_times_ms;
168 int _aux_num;
169 NumberSeq* _all_aux_times_ms;
170 double* _cur_aux_start_times_ms;
171 double* _cur_aux_times_ms;
172 bool* _cur_aux_times_set;
174 double* _par_last_ext_root_scan_times_ms;
175 double* _par_last_mark_stack_scan_times_ms;
176 double* _par_last_update_rs_start_times_ms;
177 double* _par_last_update_rs_times_ms;
178 double* _par_last_update_rs_processed_buffers;
179 double* _par_last_scan_rs_start_times_ms;
180 double* _par_last_scan_rs_times_ms;
181 double* _par_last_scan_new_refs_times_ms;
182 double* _par_last_obj_copy_times_ms;
183 double* _par_last_termination_times_ms;
185 // indicates that we are in young GC mode
186 bool _in_young_gc_mode;
188 // indicates whether we are in full young or partially young GC mode
189 bool _full_young_gcs;
191 // if true, then it tries to dynamically adjust the length of the
192 // young list
193 bool _adaptive_young_list_length;
194 size_t _young_list_min_length;
195 size_t _young_list_target_length;
196 size_t _young_list_fixed_length;
198 size_t _young_cset_length;
199 bool _last_young_gc_full;
201 double _target_pause_time_ms;
203 unsigned _full_young_pause_num;
204 unsigned _partial_young_pause_num;
206 bool _during_marking;
207 bool _in_marking_window;
208 bool _in_marking_window_im;
210 SurvRateGroup* _short_lived_surv_rate_group;
211 SurvRateGroup* _survivor_surv_rate_group;
212 // add here any more surv rate groups
214 double _gc_overhead_perc;
216 bool during_marking() {
217 return _during_marking;
218 }
220 // <NEW PREDICTION>
222 private:
223 enum PredictionConstants {
224 TruncatedSeqLength = 10
225 };
227 TruncatedSeq* _alloc_rate_ms_seq;
228 double _prev_collection_pause_end_ms;
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;
242 TruncatedSeq* _pending_cards_seq;
243 TruncatedSeq* _scanned_cards_seq;
244 TruncatedSeq* _rs_lengths_seq;
246 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
248 TruncatedSeq* _young_gc_eff_seq;
250 TruncatedSeq* _max_conc_overhead_seq;
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 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;
324 public:
326 void set_region_short_lived(HeapRegion* hr) {
327 hr->install_surv_rate_group(_short_lived_surv_rate_group);
328 }
330 void set_region_survivors(HeapRegion* hr) {
331 hr->install_surv_rate_group(_survivor_surv_rate_group);
332 }
334 #ifndef PRODUCT
335 bool verify_young_ages();
336 #endif // PRODUCT
338 double get_new_prediction(TruncatedSeq* seq) {
339 return MAX2(seq->davg() + sigma() * seq->dsd(),
340 seq->davg() * confidence_factor(seq->num()));
341 }
343 size_t young_cset_length() {
344 return _young_cset_length;
345 }
347 void record_max_rs_lengths(size_t rs_lengths) {
348 _max_rs_lengths = rs_lengths;
349 }
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 }
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;
368 return prediction;
369 }
371 size_t predict_rs_length_diff() {
372 return (size_t) get_new_prediction(_rs_length_diff_seq);
373 }
375 double predict_alloc_rate_ms() {
376 return get_new_prediction(_alloc_rate_ms_seq);
377 }
379 double predict_cost_per_card_ms() {
380 return get_new_prediction(_cost_per_card_ms_seq);
381 }
383 double predict_rs_update_time_ms(size_t pending_cards) {
384 return (double) pending_cards * predict_cost_per_card_ms();
385 }
387 double predict_fully_young_cards_per_entry_ratio() {
388 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
389 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
440 double predict_constant_other_time_ms() {
441 return get_new_prediction(_constant_other_time_ms_seq);
442 }
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 }
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 }
456 void check_if_region_is_too_expensive(double predicted_time_ms);
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);
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);
471 void start_recording_regions();
472 void record_cset_region_info(HeapRegion* hr, bool young);
473 void record_non_young_cset_region(HeapRegion* hr);
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);
480 void end_recording_regions();
482 void record_vtime_diff_ms(double vtime_diff_ms) {
483 _vtime_diff_ms = vtime_diff_ms;
484 }
486 void record_young_free_cset_time_ms(double time_ms) {
487 _recorded_young_free_cset_time_ms = time_ms;
488 }
490 void record_non_young_free_cset_time_ms(double time_ms) {
491 _recorded_non_young_free_cset_time_ms = time_ms;
492 }
494 double predict_young_gc_eff() {
495 return get_new_neg_prediction(_young_gc_eff_seq);
496 }
498 double predict_survivor_regions_evac_time();
500 // </NEW PREDICTION>
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 }
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 }
516 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
517 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
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 }
524 G1MMUTracker* mmu_tracker() {
525 return _mmu_tracker;
526 }
528 double predict_init_time_ms() {
529 return get_new_prediction(_concurrent_mark_init_times_ms);
530 }
532 double predict_remark_time_ms() {
533 return get_new_prediction(_concurrent_mark_remark_times_ms);
534 }
536 double predict_cleanup_time_ms() {
537 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
538 }
540 // Returns an estimate of the survival rate of the region at yg-age
541 // "yg_age".
542 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
543 TruncatedSeq* seq = surv_rate_group->get_seq(age);
544 if (seq->num() == 0)
545 gclog_or_tty->print("BARF! age is %d", age);
546 guarantee( seq->num() > 0, "invariant" );
547 double pred = get_new_prediction(seq);
548 if (pred > 1.0)
549 pred = 1.0;
550 return pred;
551 }
553 double predict_yg_surv_rate(int age) {
554 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
555 }
557 double accum_yg_surv_rate_pred(int age) {
558 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
559 }
561 protected:
562 void print_stats (int level, const char* str, double value);
563 void print_stats (int level, const char* str, int value);
564 void print_par_stats (int level, const char* str, double* data) {
565 print_par_stats(level, str, data, true);
566 }
567 void print_par_stats (int level, const char* str, double* data, bool summary);
568 void print_par_buffers (int level, const char* str, double* data, bool summary);
570 void check_other_times(int level,
571 NumberSeq* other_times_ms,
572 NumberSeq* calc_other_times_ms) const;
574 void print_summary (PauseSummary* stats) const;
575 void print_abandoned_summary(PauseSummary* summary) const;
577 void print_summary (int level, const char* str, NumberSeq* seq) const;
578 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
580 double avg_value (double* data);
581 double max_value (double* data);
582 double sum_of_values (double* data);
583 double max_sum (double* data1, double* data2);
585 int _last_satb_drain_processed_buffers;
586 int _last_update_rs_processed_buffers;
587 double _last_pause_time_ms;
589 size_t _bytes_in_to_space_before_gc;
590 size_t _bytes_in_to_space_after_gc;
591 size_t bytes_in_to_space_during_gc() {
592 return
593 _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc;
594 }
595 size_t _bytes_in_collection_set_before_gc;
596 // Used to count used bytes in CS.
597 friend class CountCSClosure;
599 // Statistics kept per GC stoppage, pause or full.
600 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
602 // We track markings.
603 int _num_markings;
604 double _mark_thread_startup_sec; // Time at startup of marking thread
606 // Add a new GC of the given duration and end time to the record.
607 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
609 // The head of the list (via "next_in_collection_set()") representing the
610 // current collection set. Set from the incrementally built collection
611 // set at the start of the pause.
612 HeapRegion* _collection_set;
614 // The number of regions in the collection set. Set from the incrementally
615 // built collection set at the start of an evacuation pause.
616 size_t _collection_set_size;
618 // The number of bytes in the collection set before the pause. Set from
619 // the incrementally built collection set at the start of an evacuation
620 // pause.
621 size_t _collection_set_bytes_used_before;
623 // The associated information that is maintained while the incremental
624 // collection set is being built with young regions. Used to populate
625 // the recorded info for the evacuation pause.
627 enum CSetBuildType {
628 Active, // We are actively building the collection set
629 Inactive // We are not actively building the collection set
630 };
632 CSetBuildType _inc_cset_build_state;
634 // The head of the incrementally built collection set.
635 HeapRegion* _inc_cset_head;
637 // The tail of the incrementally built collection set.
638 HeapRegion* _inc_cset_tail;
640 // The number of regions in the incrementally built collection set.
641 // Used to set _collection_set_size at the start of an evacuation
642 // pause.
643 size_t _inc_cset_size;
645 // Used as the index in the surving young words structure
646 // which tracks the amount of space, for each young region,
647 // that survives the pause.
648 size_t _inc_cset_young_index;
650 // The number of bytes in the incrementally built collection set.
651 // Used to set _collection_set_bytes_used_before at the start of
652 // an evacuation pause.
653 size_t _inc_cset_bytes_used_before;
655 // Used to record the highest end of heap region in collection set
656 HeapWord* _inc_cset_max_finger;
658 // The number of recorded used bytes in the young regions
659 // of the collection set. This is the sum of the used() bytes
660 // of retired young regions in the collection set.
661 size_t _inc_cset_recorded_young_bytes;
663 // The RSet lengths recorded for regions in the collection set
664 // (updated by the periodic sampling of the regions in the
665 // young list/collection set).
666 size_t _inc_cset_recorded_rs_lengths;
668 // The predicted elapsed time it will take to collect the regions
669 // in the collection set (updated by the periodic sampling of the
670 // regions in the young list/collection set).
671 double _inc_cset_predicted_elapsed_time_ms;
673 // The predicted bytes to copy for the regions in the collection
674 // set (updated by the periodic sampling of the regions in the
675 // young list/collection set).
676 size_t _inc_cset_predicted_bytes_to_copy;
678 // Info about marking.
679 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
681 // The number of collection pauses at the end of the last mark.
682 size_t _n_pauses_at_mark_end;
684 // Stash a pointer to the g1 heap.
685 G1CollectedHeap* _g1;
687 // The average time in ms per collection pause, averaged over recent pauses.
688 double recent_avg_time_for_pauses_ms();
690 // The average time in ms for processing CollectedHeap strong roots, per
691 // collection pause, averaged over recent pauses.
692 double recent_avg_time_for_CH_strong_ms();
694 // The average time in ms for processing the G1 remembered set, per
695 // pause, averaged over recent pauses.
696 double recent_avg_time_for_G1_strong_ms();
698 // The average time in ms for "evacuating followers", per pause, averaged
699 // over recent pauses.
700 double recent_avg_time_for_evac_ms();
702 // The number of "recent" GCs recorded in the number sequences
703 int number_of_recent_gcs();
705 // The average survival ratio, computed by the total number of bytes
706 // suriviving / total number of bytes before collection over the last
707 // several recent pauses.
708 double recent_avg_survival_fraction();
709 // The survival fraction of the most recent pause; if there have been no
710 // pauses, returns 1.0.
711 double last_survival_fraction();
713 // Returns a "conservative" estimate of the recent survival rate, i.e.,
714 // one that may be higher than "recent_avg_survival_fraction".
715 // This is conservative in several ways:
716 // If there have been few pauses, it will assume a potential high
717 // variance, and err on the side of caution.
718 // It puts a lower bound (currently 0.1) on the value it will return.
719 // To try to detect phase changes, if the most recent pause ("latest") has a
720 // higher-than average ("avg") survival rate, it returns that rate.
721 // "work" version is a utility function; young is restricted to young regions.
722 double conservative_avg_survival_fraction_work(double avg,
723 double latest);
725 // The arguments are the two sequences that keep track of the number of bytes
726 // surviving and the total number of bytes before collection, resp.,
727 // over the last evereal recent pauses
728 // Returns the survival rate for the category in the most recent pause.
729 // If there have been no pauses, returns 1.0.
730 double last_survival_fraction_work(TruncatedSeq* surviving,
731 TruncatedSeq* before);
733 // The arguments are the two sequences that keep track of the number of bytes
734 // surviving and the total number of bytes before collection, resp.,
735 // over the last several recent pauses
736 // Returns the average survival ration over the last several recent pauses
737 // If there have been no pauses, return 1.0
738 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
739 TruncatedSeq* before);
741 double conservative_avg_survival_fraction() {
742 double avg = recent_avg_survival_fraction();
743 double latest = last_survival_fraction();
744 return conservative_avg_survival_fraction_work(avg, latest);
745 }
747 // The ratio of gc time to elapsed time, computed over recent pauses.
748 double _recent_avg_pause_time_ratio;
750 double recent_avg_pause_time_ratio() {
751 return _recent_avg_pause_time_ratio;
752 }
754 // Number of pauses between concurrent marking.
755 size_t _pauses_btwn_concurrent_mark;
757 size_t _n_marks_since_last_pause;
759 // At the end of a pause we check the heap occupancy and we decide
760 // whether we will start a marking cycle during the next pause. If
761 // we decide that we want to do that, we will set this parameter to
762 // true. So, this parameter will stay true between the end of a
763 // pause and the beginning of a subsequent pause (not necessarily
764 // the next one, see the comments on the next field) when we decide
765 // that we will indeed start a marking cycle and do the initial-mark
766 // work.
767 volatile bool _initiate_conc_mark_if_possible;
769 // If initiate_conc_mark_if_possible() is set at the beginning of a
770 // pause, it is a suggestion that the pause should start a marking
771 // cycle by doing the initial-mark work. However, it is possible
772 // that the concurrent marking thread is still finishing up the
773 // previous marking cycle (e.g., clearing the next marking
774 // bitmap). If that is the case we cannot start a new cycle and
775 // we'll have to wait for the concurrent marking thread to finish
776 // what it is doing. In this case we will postpone the marking cycle
777 // initiation decision for the next pause. When we eventually decide
778 // to start a cycle, we will set _during_initial_mark_pause which
779 // will stay true until the end of the initial-mark pause and it's
780 // the condition that indicates that a pause is doing the
781 // initial-mark work.
782 volatile bool _during_initial_mark_pause;
784 bool _should_revert_to_full_young_gcs;
785 bool _last_full_young_gc;
787 // This set of variables tracks the collector efficiency, in order to
788 // determine whether we should initiate a new marking.
789 double _cur_mark_stop_world_time_ms;
790 double _mark_init_start_sec;
791 double _mark_remark_start_sec;
792 double _mark_cleanup_start_sec;
793 double _mark_closure_time_ms;
795 void calculate_young_list_min_length();
796 void calculate_young_list_target_length();
797 void calculate_young_list_target_length(size_t rs_lengths);
799 public:
801 G1CollectorPolicy();
803 virtual G1CollectorPolicy* as_g1_policy() { return this; }
805 virtual CollectorPolicy::Name kind() {
806 return CollectorPolicy::G1CollectorPolicyKind;
807 }
809 void check_prediction_validity();
811 size_t bytes_in_collection_set() {
812 return _bytes_in_collection_set_before_gc;
813 }
815 size_t bytes_in_to_space() {
816 return bytes_in_to_space_during_gc();
817 }
819 unsigned calc_gc_alloc_time_stamp() {
820 return _all_pause_times_ms->num() + 1;
821 }
823 protected:
825 // Count the number of bytes used in the CS.
826 void count_CS_bytes_used();
828 // Together these do the base cleanup-recording work. Subclasses might
829 // want to put something between them.
830 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
831 size_t max_live_bytes);
832 void record_concurrent_mark_cleanup_end_work2();
834 public:
836 virtual void init();
838 // Create jstat counters for the policy.
839 virtual void initialize_gc_policy_counters();
841 virtual HeapWord* mem_allocate_work(size_t size,
842 bool is_tlab,
843 bool* gc_overhead_limit_was_exceeded);
845 // This method controls how a collector handles one or more
846 // of its generations being fully allocated.
847 virtual HeapWord* satisfy_failed_allocation(size_t size,
848 bool is_tlab);
850 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
852 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
854 // The number of collection pauses so far.
855 long n_pauses() const { return _n_pauses; }
857 // Update the heuristic info to record a collection pause of the given
858 // start time, where the given number of bytes were used at the start.
859 // This may involve changing the desired size of a collection set.
861 virtual void record_stop_world_start();
863 virtual void record_collection_pause_start(double start_time_sec,
864 size_t start_used);
866 // Must currently be called while the world is stopped.
867 virtual void record_concurrent_mark_init_start();
868 virtual void record_concurrent_mark_init_end();
869 void record_concurrent_mark_init_end_pre(double
870 mark_init_elapsed_time_ms);
872 void record_mark_closure_time(double mark_closure_time_ms);
874 virtual void record_concurrent_mark_remark_start();
875 virtual void record_concurrent_mark_remark_end();
877 virtual void record_concurrent_mark_cleanup_start();
878 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
879 size_t max_live_bytes);
880 virtual void record_concurrent_mark_cleanup_completed();
882 virtual void record_concurrent_pause();
883 virtual void record_concurrent_pause_end();
885 virtual void record_collection_pause_end_CH_strong_roots();
886 virtual void record_collection_pause_end_G1_strong_roots();
888 virtual void record_collection_pause_end(bool abandoned);
890 // Record the fact that a full collection occurred.
891 virtual void record_full_collection_start();
892 virtual void record_full_collection_end();
894 void record_ext_root_scan_time(int worker_i, double ms) {
895 _par_last_ext_root_scan_times_ms[worker_i] = ms;
896 }
898 void record_mark_stack_scan_time(int worker_i, double ms) {
899 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
900 }
902 void record_satb_drain_time(double ms) {
903 _cur_satb_drain_time_ms = ms;
904 _satb_drain_time_set = true;
905 }
907 void record_satb_drain_processed_buffers (int processed_buffers) {
908 _last_satb_drain_processed_buffers = processed_buffers;
909 }
911 void record_mod_union_time(double ms) {
912 _all_mod_union_times_ms->add(ms);
913 }
915 void record_update_rs_start_time(int thread, double ms) {
916 _par_last_update_rs_start_times_ms[thread] = ms;
917 }
919 void record_update_rs_time(int thread, double ms) {
920 _par_last_update_rs_times_ms[thread] = ms;
921 }
923 void record_update_rs_processed_buffers (int thread,
924 double processed_buffers) {
925 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
926 }
928 void record_scan_rs_start_time(int thread, double ms) {
929 _par_last_scan_rs_start_times_ms[thread] = ms;
930 }
932 void record_scan_rs_time(int thread, double ms) {
933 _par_last_scan_rs_times_ms[thread] = ms;
934 }
936 void record_scan_new_refs_time(int thread, double ms) {
937 _par_last_scan_new_refs_times_ms[thread] = ms;
938 }
940 double get_scan_new_refs_time(int thread) {
941 return _par_last_scan_new_refs_times_ms[thread];
942 }
944 void reset_obj_copy_time(int thread) {
945 _par_last_obj_copy_times_ms[thread] = 0.0;
946 }
948 void reset_obj_copy_time() {
949 reset_obj_copy_time(0);
950 }
952 void record_obj_copy_time(int thread, double ms) {
953 _par_last_obj_copy_times_ms[thread] += ms;
954 }
956 void record_obj_copy_time(double ms) {
957 record_obj_copy_time(0, ms);
958 }
960 void record_termination_time(int thread, double ms) {
961 _par_last_termination_times_ms[thread] = ms;
962 }
964 void record_termination_time(double ms) {
965 record_termination_time(0, ms);
966 }
968 void record_pause_time_ms(double ms) {
969 _last_pause_time_ms = ms;
970 }
972 void record_clear_ct_time(double ms) {
973 _cur_clear_ct_time_ms = ms;
974 }
976 void record_par_time(double ms) {
977 _cur_collection_par_time_ms = ms;
978 }
980 void record_aux_start_time(int i) {
981 guarantee(i < _aux_num, "should be within range");
982 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
983 }
985 void record_aux_end_time(int i) {
986 guarantee(i < _aux_num, "should be within range");
987 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
988 _cur_aux_times_set[i] = true;
989 _cur_aux_times_ms[i] += ms;
990 }
992 #ifndef PRODUCT
993 void record_cc_clear_time(double ms) {
994 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
995 _min_clear_cc_time_ms = ms;
996 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
997 _max_clear_cc_time_ms = ms;
998 _cur_clear_cc_time_ms = ms;
999 _cum_clear_cc_time_ms += ms;
1000 _num_cc_clears++;
1001 }
1002 #endif
1004 // Record the fact that "bytes" bytes allocated in a region.
1005 void record_before_bytes(size_t bytes);
1006 void record_after_bytes(size_t bytes);
1008 // Returns "true" if this is a good time to do a collection pause.
1009 // The "word_size" argument, if non-zero, indicates the size of an
1010 // allocation request that is prompting this query.
1011 virtual bool should_do_collection_pause(size_t word_size) = 0;
1013 // Choose a new collection set. Marks the chosen regions as being
1014 // "in_collection_set", and links them together. The head and number of
1015 // the collection set are available via access methods.
1016 virtual bool choose_collection_set() = 0;
1018 // The head of the list (via "next_in_collection_set()") representing the
1019 // current collection set.
1020 HeapRegion* collection_set() { return _collection_set; }
1022 void clear_collection_set() { _collection_set = NULL; }
1024 // The number of elements in the current collection set.
1025 size_t collection_set_size() { return _collection_set_size; }
1027 // Add "hr" to the CS.
1028 void add_to_collection_set(HeapRegion* hr);
1030 // Incremental CSet Support
1032 // The head of the incrementally built collection set.
1033 HeapRegion* inc_cset_head() { return _inc_cset_head; }
1035 // The tail of the incrementally built collection set.
1036 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
1038 // The number of elements in the incrementally built collection set.
1039 size_t inc_cset_size() { return _inc_cset_size; }
1041 // Initialize incremental collection set info.
1042 void start_incremental_cset_building();
1044 void clear_incremental_cset() {
1045 _inc_cset_head = NULL;
1046 _inc_cset_tail = NULL;
1047 }
1049 // Stop adding regions to the incremental collection set
1050 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
1052 // Add/remove information about hr to the aggregated information
1053 // for the incrementally built collection set.
1054 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
1055 void remove_from_incremental_cset_info(HeapRegion* hr);
1057 // Update information about hr in the aggregated information for
1058 // the incrementally built collection set.
1059 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
1061 private:
1062 // Update the incremental cset information when adding a region
1063 // (should not be called directly).
1064 void add_region_to_incremental_cset_common(HeapRegion* hr);
1066 public:
1067 // Add hr to the LHS of the incremental collection set.
1068 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1070 // Add hr to the RHS of the incremental collection set.
1071 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1073 #ifndef PRODUCT
1074 void print_collection_set(HeapRegion* list_head, outputStream* st);
1075 #endif // !PRODUCT
1077 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1078 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1079 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1081 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1082 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1083 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1085 // This is called at the very beginning of an evacuation pause (it
1086 // has to be the first thing that the pause does). If
1087 // initiate_conc_mark_if_possible() is true, and the concurrent
1088 // marking thread has completed its work during the previous cycle,
1089 // it will set during_initial_mark_pause() to so that the pause does
1090 // the initial-mark work and start a marking cycle.
1091 void decide_on_conc_mark_initiation();
1093 // If an expansion would be appropriate, because recent GC overhead had
1094 // exceeded the desired limit, return an amount to expand by.
1095 virtual size_t expansion_amount();
1097 // note start of mark thread
1098 void note_start_of_mark_thread();
1100 // The marked bytes of the "r" has changed; reclassify it's desirability
1101 // for marking. Also asserts that "r" is eligible for a CS.
1102 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
1104 #ifndef PRODUCT
1105 // Check any appropriate marked bytes info, asserting false if
1106 // something's wrong, else returning "true".
1107 virtual bool assertMarkedBytesDataOK() = 0;
1108 #endif
1110 // Print tracing information.
1111 void print_tracing_info() const;
1113 // Print stats on young survival ratio
1114 void print_yg_surv_rate_info() const;
1116 void finished_recalculating_age_indexes(bool is_survivors) {
1117 if (is_survivors) {
1118 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1119 } else {
1120 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1121 }
1122 // do that for any other surv rate groups
1123 }
1125 bool should_add_next_region_to_young_list();
1127 bool in_young_gc_mode() {
1128 return _in_young_gc_mode;
1129 }
1130 void set_in_young_gc_mode(bool in_young_gc_mode) {
1131 _in_young_gc_mode = in_young_gc_mode;
1132 }
1134 bool full_young_gcs() {
1135 return _full_young_gcs;
1136 }
1137 void set_full_young_gcs(bool full_young_gcs) {
1138 _full_young_gcs = full_young_gcs;
1139 }
1141 bool adaptive_young_list_length() {
1142 return _adaptive_young_list_length;
1143 }
1144 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1145 _adaptive_young_list_length = adaptive_young_list_length;
1146 }
1148 inline double get_gc_eff_factor() {
1149 double ratio = _known_garbage_ratio;
1151 double square = ratio * ratio;
1152 // square = square * square;
1153 double ret = square * 9.0 + 1.0;
1154 #if 0
1155 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1156 #endif // 0
1157 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1158 return ret;
1159 }
1161 //
1162 // Survivor regions policy.
1163 //
1164 protected:
1166 // Current tenuring threshold, set to 0 if the collector reaches the
1167 // maximum amount of suvivors regions.
1168 int _tenuring_threshold;
1170 // The limit on the number of regions allocated for survivors.
1171 size_t _max_survivor_regions;
1173 // The amount of survor regions after a collection.
1174 size_t _recorded_survivor_regions;
1175 // List of survivor regions.
1176 HeapRegion* _recorded_survivor_head;
1177 HeapRegion* _recorded_survivor_tail;
1179 ageTable _survivors_age_table;
1181 public:
1183 inline GCAllocPurpose
1184 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1185 if (age < _tenuring_threshold && src_region->is_young()) {
1186 return GCAllocForSurvived;
1187 } else {
1188 return GCAllocForTenured;
1189 }
1190 }
1192 inline bool track_object_age(GCAllocPurpose purpose) {
1193 return purpose == GCAllocForSurvived;
1194 }
1196 inline GCAllocPurpose alternative_purpose(int purpose) {
1197 return GCAllocForTenured;
1198 }
1200 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1202 size_t max_regions(int purpose);
1204 // The limit on regions for a particular purpose is reached.
1205 void note_alloc_region_limit_reached(int purpose) {
1206 if (purpose == GCAllocForSurvived) {
1207 _tenuring_threshold = 0;
1208 }
1209 }
1211 void note_start_adding_survivor_regions() {
1212 _survivor_surv_rate_group->start_adding_regions();
1213 }
1215 void note_stop_adding_survivor_regions() {
1216 _survivor_surv_rate_group->stop_adding_regions();
1217 }
1219 void record_survivor_regions(size_t regions,
1220 HeapRegion* head,
1221 HeapRegion* tail) {
1222 _recorded_survivor_regions = regions;
1223 _recorded_survivor_head = head;
1224 _recorded_survivor_tail = tail;
1225 }
1227 size_t recorded_survivor_regions() {
1228 return _recorded_survivor_regions;
1229 }
1231 void record_thread_age_table(ageTable* age_table)
1232 {
1233 _survivors_age_table.merge_par(age_table);
1234 }
1236 // Calculates survivor space parameters.
1237 void calculate_survivors_policy();
1239 };
1241 // This encapsulates a particular strategy for a g1 Collector.
1242 //
1243 // Start a concurrent mark when our heap size is n bytes
1244 // greater then our heap size was at the last concurrent
1245 // mark. Where n is a function of the CMSTriggerRatio
1246 // and the MinHeapFreeRatio.
1247 //
1248 // Start a g1 collection pause when we have allocated the
1249 // average number of bytes currently being freed in
1250 // a collection, but only if it is at least one region
1251 // full
1252 //
1253 // Resize Heap based on desired
1254 // allocation space, where desired allocation space is
1255 // a function of survival rate and desired future to size.
1256 //
1257 // Choose collection set by first picking all older regions
1258 // which have a survival rate which beats our projected young
1259 // survival rate. Then fill out the number of needed regions
1260 // with young regions.
1262 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1263 CollectionSetChooser* _collectionSetChooser;
1264 // If the estimated is less then desirable, resize if possible.
1265 void expand_if_possible(size_t numRegions);
1267 virtual bool choose_collection_set();
1268 virtual void record_collection_pause_start(double start_time_sec,
1269 size_t start_used);
1270 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1271 size_t max_live_bytes);
1272 virtual void record_full_collection_end();
1274 public:
1275 G1CollectorPolicy_BestRegionsFirst() {
1276 _collectionSetChooser = new CollectionSetChooser();
1277 }
1278 void record_collection_pause_end(bool abandoned);
1279 bool should_do_collection_pause(size_t word_size);
1280 // This is not needed any more, after the CSet choosing code was
1281 // changed to use the pause prediction work. But let's leave the
1282 // hook in just in case.
1283 void note_change_in_marked_bytes(HeapRegion* r) { }
1284 #ifndef PRODUCT
1285 bool assertMarkedBytesDataOK();
1286 #endif
1287 };
1289 // This should move to some place more general...
1291 // If we have "n" measurements, and we've kept track of their "sum" and the
1292 // "sum_of_squares" of the measurements, this returns the variance of the
1293 // sequence.
1294 inline double variance(int n, double sum_of_squares, double sum) {
1295 double n_d = (double)n;
1296 double avg = sum/n_d;
1297 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1298 }
1300 // Local Variables: ***
1301 // c-indentation-style: gnu ***
1302 // End: ***