Tue, 07 Jul 2009 14:23:00 -0400
6855834: G1: minimize the output when -XX:+PrintHeapAtGC is set
Summary: Changing the behavior of -XX:+PrintHeapAtGC for G1 from printing lengthy, per-region information to instead printing a concise summary.
Reviewed-by: ysr, apetrusenko, jcoomes
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 }
116 double _cur_collection_start_sec;
117 size_t _cur_collection_pause_used_at_start_bytes;
118 size_t _cur_collection_pause_used_regions_at_start;
119 size_t _prev_collection_pause_used_at_end_bytes;
120 double _cur_collection_par_time_ms;
121 double _cur_satb_drain_time_ms;
122 double _cur_clear_ct_time_ms;
123 bool _satb_drain_time_set;
125 double _cur_CH_strong_roots_end_sec;
126 double _cur_CH_strong_roots_dur_ms;
127 double _cur_G1_strong_roots_end_sec;
128 double _cur_G1_strong_roots_dur_ms;
130 // Statistics for recent GC pauses. See below for how indexed.
131 TruncatedSeq* _recent_CH_strong_roots_times_ms;
132 TruncatedSeq* _recent_G1_strong_roots_times_ms;
133 TruncatedSeq* _recent_evac_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_init_times_ms;
144 TruncatedSeq* _concurrent_mark_remark_times_ms;
145 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
147 Summary* _summary;
148 AbandonedSummary* _abandoned_summary;
150 NumberSeq* _all_pause_times_ms;
151 NumberSeq* _all_full_gc_times_ms;
152 double _stop_world_start;
153 NumberSeq* _all_stop_world_times_ms;
154 NumberSeq* _all_yield_times_ms;
156 size_t _region_num_young;
157 size_t _region_num_tenured;
158 size_t _prev_region_num_young;
159 size_t _prev_region_num_tenured;
161 NumberSeq* _all_mod_union_times_ms;
163 int _aux_num;
164 NumberSeq* _all_aux_times_ms;
165 double* _cur_aux_start_times_ms;
166 double* _cur_aux_times_ms;
167 bool* _cur_aux_times_set;
169 double* _par_last_ext_root_scan_times_ms;
170 double* _par_last_mark_stack_scan_times_ms;
171 double* _par_last_scan_only_times_ms;
172 double* _par_last_scan_only_regions_scanned;
173 double* _par_last_update_rs_start_times_ms;
174 double* _par_last_update_rs_times_ms;
175 double* _par_last_update_rs_processed_buffers;
176 double* _par_last_scan_rs_start_times_ms;
177 double* _par_last_scan_rs_times_ms;
178 double* _par_last_scan_new_refs_times_ms;
179 double* _par_last_obj_copy_times_ms;
180 double* _par_last_termination_times_ms;
182 // indicates that we are in young GC mode
183 bool _in_young_gc_mode;
185 // indicates whether we are in full young or partially young GC mode
186 bool _full_young_gcs;
188 // if true, then it tries to dynamically adjust the length of the
189 // young list
190 bool _adaptive_young_list_length;
191 size_t _young_list_min_length;
192 size_t _young_list_target_length;
193 size_t _young_list_so_prefix_length;
194 size_t _young_list_fixed_length;
196 size_t _young_cset_length;
197 bool _last_young_gc_full;
199 double _target_pause_time_ms;
201 unsigned _full_young_pause_num;
202 unsigned _partial_young_pause_num;
204 bool _during_marking;
205 bool _in_marking_window;
206 bool _in_marking_window_im;
208 SurvRateGroup* _short_lived_surv_rate_group;
209 SurvRateGroup* _survivor_surv_rate_group;
210 // add here any more surv rate groups
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* _cost_per_scan_only_region_ms_seq;
230 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
231 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
232 TruncatedSeq* _cost_per_entry_ms_seq;
233 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
234 TruncatedSeq* _cost_per_byte_ms_seq;
235 TruncatedSeq* _constant_other_time_ms_seq;
236 TruncatedSeq* _young_other_cost_per_region_ms_seq;
237 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
239 TruncatedSeq* _pending_cards_seq;
240 TruncatedSeq* _scanned_cards_seq;
241 TruncatedSeq* _rs_lengths_seq;
243 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
244 TruncatedSeq* _cost_per_scan_only_region_ms_during_cm_seq;
246 TruncatedSeq* _young_gc_eff_seq;
248 TruncatedSeq* _max_conc_overhead_seq;
250 size_t _recorded_young_regions;
251 size_t _recorded_scan_only_regions;
252 size_t _recorded_non_young_regions;
253 size_t _recorded_region_num;
255 size_t _free_regions_at_end_of_collection;
256 size_t _scan_only_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_scan_only_scan_time_ms;
273 double _predicted_object_copy_time_ms;
274 double _predicted_constant_other_time_ms;
275 double _predicted_young_other_time_ms;
276 double _predicted_non_young_other_time_ms;
277 double _predicted_pause_time_ms;
279 double _vtime_diff_ms;
281 double _recorded_young_free_cset_time_ms;
282 double _recorded_non_young_free_cset_time_ms;
284 double _sigma;
285 double _expensive_region_limit_ms;
287 size_t _rs_lengths_prediction;
289 size_t _known_garbage_bytes;
290 double _known_garbage_ratio;
292 double sigma() {
293 return _sigma;
294 }
296 // A function that prevents us putting too much stock in small sample
297 // sets. Returns a number between 2.0 and 1.0, depending on the number
298 // of samples. 5 or more samples yields one; fewer scales linearly from
299 // 2.0 at 1 sample to 1.0 at 5.
300 double confidence_factor(int samples) {
301 if (samples > 4) return 1.0;
302 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
303 }
305 double get_new_neg_prediction(TruncatedSeq* seq) {
306 return seq->davg() - sigma() * seq->dsd();
307 }
309 #ifndef PRODUCT
310 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
311 #endif // PRODUCT
313 protected:
314 double _pause_time_target_ms;
315 double _recorded_young_cset_choice_time_ms;
316 double _recorded_non_young_cset_choice_time_ms;
317 bool _within_target;
318 size_t _pending_cards;
319 size_t _max_pending_cards;
321 public:
323 void set_region_short_lived(HeapRegion* hr) {
324 hr->install_surv_rate_group(_short_lived_surv_rate_group);
325 }
327 void set_region_survivors(HeapRegion* hr) {
328 hr->install_surv_rate_group(_survivor_surv_rate_group);
329 }
331 #ifndef PRODUCT
332 bool verify_young_ages();
333 #endif // PRODUCT
335 void tag_scan_only(size_t short_lived_scan_only_length);
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_scan_only_time_ms_during_cm(size_t scan_only_region_num) {
423 if (_cost_per_scan_only_region_ms_during_cm_seq->num() < 3)
424 return 1.5 * (double) scan_only_region_num *
425 get_new_prediction(_cost_per_scan_only_region_ms_seq);
426 else
427 return (double) scan_only_region_num *
428 get_new_prediction(_cost_per_scan_only_region_ms_during_cm_seq);
429 }
431 double predict_scan_only_time_ms(size_t scan_only_region_num) {
432 if (_in_marking_window_im)
433 return predict_scan_only_time_ms_during_cm(scan_only_region_num);
434 else
435 return (double) scan_only_region_num *
436 get_new_prediction(_cost_per_scan_only_region_ms_seq);
437 }
439 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
440 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
441 return 1.1 * (double) bytes_to_copy *
442 get_new_prediction(_cost_per_byte_ms_seq);
443 else
444 return (double) bytes_to_copy *
445 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
446 }
448 double predict_object_copy_time_ms(size_t bytes_to_copy) {
449 if (_in_marking_window && !_in_marking_window_im)
450 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
451 else
452 return (double) bytes_to_copy *
453 get_new_prediction(_cost_per_byte_ms_seq);
454 }
456 double predict_constant_other_time_ms() {
457 return get_new_prediction(_constant_other_time_ms_seq);
458 }
460 double predict_young_other_time_ms(size_t young_num) {
461 return
462 (double) young_num *
463 get_new_prediction(_young_other_cost_per_region_ms_seq);
464 }
466 double predict_non_young_other_time_ms(size_t non_young_num) {
467 return
468 (double) non_young_num *
469 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
470 }
472 void check_if_region_is_too_expensive(double predicted_time_ms);
474 double predict_young_collection_elapsed_time_ms(size_t adjustment);
475 double predict_base_elapsed_time_ms(size_t pending_cards);
476 double predict_base_elapsed_time_ms(size_t pending_cards,
477 size_t scanned_cards);
478 size_t predict_bytes_to_copy(HeapRegion* hr);
479 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
481 // for use by: calculate_optimal_so_length(length)
482 void predict_gc_eff(size_t young_region_num,
483 size_t so_length,
484 double base_time_ms,
485 double *gc_eff,
486 double *pause_time_ms);
488 // for use by: calculate_young_list_target_config(rs_length)
489 bool predict_gc_eff(size_t young_region_num,
490 size_t so_length,
491 double base_time_with_so_ms,
492 size_t init_free_regions,
493 double target_pause_time_ms,
494 double* gc_eff);
496 void start_recording_regions();
497 void record_cset_region(HeapRegion* hr, bool young);
498 void record_scan_only_regions(size_t scan_only_length);
499 void end_recording_regions();
501 void record_vtime_diff_ms(double vtime_diff_ms) {
502 _vtime_diff_ms = vtime_diff_ms;
503 }
505 void record_young_free_cset_time_ms(double time_ms) {
506 _recorded_young_free_cset_time_ms = time_ms;
507 }
509 void record_non_young_free_cset_time_ms(double time_ms) {
510 _recorded_non_young_free_cset_time_ms = time_ms;
511 }
513 double predict_young_gc_eff() {
514 return get_new_neg_prediction(_young_gc_eff_seq);
515 }
517 double predict_survivor_regions_evac_time();
519 // </NEW PREDICTION>
521 public:
522 void cset_regions_freed() {
523 bool propagate = _last_young_gc_full && !_in_marking_window;
524 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
525 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
526 // also call it on any more surv rate groups
527 }
529 void set_known_garbage_bytes(size_t known_garbage_bytes) {
530 _known_garbage_bytes = known_garbage_bytes;
531 size_t heap_bytes = _g1->capacity();
532 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
533 }
535 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
536 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
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 G1MMUTracker* mmu_tracker() {
544 return _mmu_tracker;
545 }
547 double predict_init_time_ms() {
548 return get_new_prediction(_concurrent_mark_init_times_ms);
549 }
551 double predict_remark_time_ms() {
552 return get_new_prediction(_concurrent_mark_remark_times_ms);
553 }
555 double predict_cleanup_time_ms() {
556 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
557 }
559 // Returns an estimate of the survival rate of the region at yg-age
560 // "yg_age".
561 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
562 TruncatedSeq* seq = surv_rate_group->get_seq(age);
563 if (seq->num() == 0)
564 gclog_or_tty->print("BARF! age is %d", age);
565 guarantee( seq->num() > 0, "invariant" );
566 double pred = get_new_prediction(seq);
567 if (pred > 1.0)
568 pred = 1.0;
569 return pred;
570 }
572 double predict_yg_surv_rate(int age) {
573 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
574 }
576 double accum_yg_surv_rate_pred(int age) {
577 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
578 }
580 protected:
581 void print_stats (int level, const char* str, double value);
582 void print_stats (int level, const char* str, int value);
583 void print_par_stats (int level, const char* str, double* data) {
584 print_par_stats(level, str, data, true);
585 }
586 void print_par_stats (int level, const char* str, double* data, bool summary);
587 void print_par_buffers (int level, const char* str, double* data, bool summary);
589 void check_other_times(int level,
590 NumberSeq* other_times_ms,
591 NumberSeq* calc_other_times_ms) const;
593 void print_summary (PauseSummary* stats) const;
594 void print_abandoned_summary(PauseSummary* summary) const;
596 void print_summary (int level, const char* str, NumberSeq* seq) const;
597 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
599 double avg_value (double* data);
600 double max_value (double* data);
601 double sum_of_values (double* data);
602 double max_sum (double* data1, double* data2);
604 int _last_satb_drain_processed_buffers;
605 int _last_update_rs_processed_buffers;
606 double _last_pause_time_ms;
608 size_t _bytes_in_to_space_before_gc;
609 size_t _bytes_in_to_space_after_gc;
610 size_t bytes_in_to_space_during_gc() {
611 return
612 _bytes_in_to_space_after_gc - _bytes_in_to_space_before_gc;
613 }
614 size_t _bytes_in_collection_set_before_gc;
615 // Used to count used bytes in CS.
616 friend class CountCSClosure;
618 // Statistics kept per GC stoppage, pause or full.
619 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
621 // We track markings.
622 int _num_markings;
623 double _mark_thread_startup_sec; // Time at startup of marking thread
625 // Add a new GC of the given duration and end time to the record.
626 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
628 // The head of the list (via "next_in_collection_set()") representing the
629 // current collection set.
630 HeapRegion* _collection_set;
631 size_t _collection_set_size;
632 size_t _collection_set_bytes_used_before;
634 // Info about marking.
635 int _n_marks; // Sticky at 2, so we know when we've done at least 2.
637 // The number of collection pauses at the end of the last mark.
638 size_t _n_pauses_at_mark_end;
640 // Stash a pointer to the g1 heap.
641 G1CollectedHeap* _g1;
643 // The average time in ms per collection pause, averaged over recent pauses.
644 double recent_avg_time_for_pauses_ms();
646 // The average time in ms for processing CollectedHeap strong roots, per
647 // collection pause, averaged over recent pauses.
648 double recent_avg_time_for_CH_strong_ms();
650 // The average time in ms for processing the G1 remembered set, per
651 // pause, averaged over recent pauses.
652 double recent_avg_time_for_G1_strong_ms();
654 // The average time in ms for "evacuating followers", per pause, averaged
655 // over recent pauses.
656 double recent_avg_time_for_evac_ms();
658 // The number of "recent" GCs recorded in the number sequences
659 int number_of_recent_gcs();
661 // The average survival ratio, computed by the total number of bytes
662 // suriviving / total number of bytes before collection over the last
663 // several recent pauses.
664 double recent_avg_survival_fraction();
665 // The survival fraction of the most recent pause; if there have been no
666 // pauses, returns 1.0.
667 double last_survival_fraction();
669 // Returns a "conservative" estimate of the recent survival rate, i.e.,
670 // one that may be higher than "recent_avg_survival_fraction".
671 // This is conservative in several ways:
672 // If there have been few pauses, it will assume a potential high
673 // variance, and err on the side of caution.
674 // It puts a lower bound (currently 0.1) on the value it will return.
675 // To try to detect phase changes, if the most recent pause ("latest") has a
676 // higher-than average ("avg") survival rate, it returns that rate.
677 // "work" version is a utility function; young is restricted to young regions.
678 double conservative_avg_survival_fraction_work(double avg,
679 double latest);
681 // The arguments are the two sequences that keep track of the number of bytes
682 // surviving and the total number of bytes before collection, resp.,
683 // over the last evereal recent pauses
684 // Returns the survival rate for the category in the most recent pause.
685 // If there have been no pauses, returns 1.0.
686 double last_survival_fraction_work(TruncatedSeq* surviving,
687 TruncatedSeq* before);
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 several recent pauses
692 // Returns the average survival ration over the last several recent pauses
693 // If there have been no pauses, return 1.0
694 double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
695 TruncatedSeq* before);
697 double conservative_avg_survival_fraction() {
698 double avg = recent_avg_survival_fraction();
699 double latest = last_survival_fraction();
700 return conservative_avg_survival_fraction_work(avg, latest);
701 }
703 // The ratio of gc time to elapsed time, computed over recent pauses.
704 double _recent_avg_pause_time_ratio;
706 double recent_avg_pause_time_ratio() {
707 return _recent_avg_pause_time_ratio;
708 }
710 // Number of pauses between concurrent marking.
711 size_t _pauses_btwn_concurrent_mark;
713 size_t _n_marks_since_last_pause;
715 // True iff CM has been initiated.
716 bool _conc_mark_initiated;
718 // True iff CM should be initiated
719 bool _should_initiate_conc_mark;
720 bool _should_revert_to_full_young_gcs;
721 bool _last_full_young_gc;
723 // This set of variables tracks the collector efficiency, in order to
724 // determine whether we should initiate a new marking.
725 double _cur_mark_stop_world_time_ms;
726 double _mark_init_start_sec;
727 double _mark_remark_start_sec;
728 double _mark_cleanup_start_sec;
729 double _mark_closure_time_ms;
731 void calculate_young_list_min_length();
732 void calculate_young_list_target_config();
733 void calculate_young_list_target_config(size_t rs_lengths);
734 size_t calculate_optimal_so_length(size_t young_list_length);
736 public:
738 G1CollectorPolicy();
740 virtual G1CollectorPolicy* as_g1_policy() { return this; }
742 virtual CollectorPolicy::Name kind() {
743 return CollectorPolicy::G1CollectorPolicyKind;
744 }
746 void check_prediction_validity();
748 size_t bytes_in_collection_set() {
749 return _bytes_in_collection_set_before_gc;
750 }
752 size_t bytes_in_to_space() {
753 return bytes_in_to_space_during_gc();
754 }
756 unsigned calc_gc_alloc_time_stamp() {
757 return _all_pause_times_ms->num() + 1;
758 }
760 protected:
762 // Count the number of bytes used in the CS.
763 void count_CS_bytes_used();
765 // Together these do the base cleanup-recording work. Subclasses might
766 // want to put something between them.
767 void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
768 size_t max_live_bytes);
769 void record_concurrent_mark_cleanup_end_work2();
771 public:
773 virtual void init();
775 // Create jstat counters for the policy.
776 virtual void initialize_gc_policy_counters();
778 virtual HeapWord* mem_allocate_work(size_t size,
779 bool is_tlab,
780 bool* gc_overhead_limit_was_exceeded);
782 // This method controls how a collector handles one or more
783 // of its generations being fully allocated.
784 virtual HeapWord* satisfy_failed_allocation(size_t size,
785 bool is_tlab);
787 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
789 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
791 // The number of collection pauses so far.
792 long n_pauses() const { return _n_pauses; }
794 // Update the heuristic info to record a collection pause of the given
795 // start time, where the given number of bytes were used at the start.
796 // This may involve changing the desired size of a collection set.
798 virtual void record_stop_world_start();
800 virtual void record_collection_pause_start(double start_time_sec,
801 size_t start_used);
803 // Must currently be called while the world is stopped.
804 virtual void record_concurrent_mark_init_start();
805 virtual void record_concurrent_mark_init_end();
806 void record_concurrent_mark_init_end_pre(double
807 mark_init_elapsed_time_ms);
809 void record_mark_closure_time(double mark_closure_time_ms);
811 virtual void record_concurrent_mark_remark_start();
812 virtual void record_concurrent_mark_remark_end();
814 virtual void record_concurrent_mark_cleanup_start();
815 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
816 size_t max_live_bytes);
817 virtual void record_concurrent_mark_cleanup_completed();
819 virtual void record_concurrent_pause();
820 virtual void record_concurrent_pause_end();
822 virtual void record_collection_pause_end_CH_strong_roots();
823 virtual void record_collection_pause_end_G1_strong_roots();
825 virtual void record_collection_pause_end(bool abandoned);
827 // Record the fact that a full collection occurred.
828 virtual void record_full_collection_start();
829 virtual void record_full_collection_end();
831 void record_ext_root_scan_time(int worker_i, double ms) {
832 _par_last_ext_root_scan_times_ms[worker_i] = ms;
833 }
835 void record_mark_stack_scan_time(int worker_i, double ms) {
836 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
837 }
839 void record_scan_only_time(int worker_i, double ms, int n) {
840 _par_last_scan_only_times_ms[worker_i] = ms;
841 _par_last_scan_only_regions_scanned[worker_i] = (double) n;
842 }
844 void record_satb_drain_time(double ms) {
845 _cur_satb_drain_time_ms = ms;
846 _satb_drain_time_set = true;
847 }
849 void record_satb_drain_processed_buffers (int processed_buffers) {
850 _last_satb_drain_processed_buffers = processed_buffers;
851 }
853 void record_mod_union_time(double ms) {
854 _all_mod_union_times_ms->add(ms);
855 }
857 void record_update_rs_start_time(int thread, double ms) {
858 _par_last_update_rs_start_times_ms[thread] = ms;
859 }
861 void record_update_rs_time(int thread, double ms) {
862 _par_last_update_rs_times_ms[thread] = ms;
863 }
865 void record_update_rs_processed_buffers (int thread,
866 double processed_buffers) {
867 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
868 }
870 void record_scan_rs_start_time(int thread, double ms) {
871 _par_last_scan_rs_start_times_ms[thread] = ms;
872 }
874 void record_scan_rs_time(int thread, double ms) {
875 _par_last_scan_rs_times_ms[thread] = ms;
876 }
878 void record_scan_new_refs_time(int thread, double ms) {
879 _par_last_scan_new_refs_times_ms[thread] = ms;
880 }
882 double get_scan_new_refs_time(int thread) {
883 return _par_last_scan_new_refs_times_ms[thread];
884 }
886 void reset_obj_copy_time(int thread) {
887 _par_last_obj_copy_times_ms[thread] = 0.0;
888 }
890 void reset_obj_copy_time() {
891 reset_obj_copy_time(0);
892 }
894 void record_obj_copy_time(int thread, double ms) {
895 _par_last_obj_copy_times_ms[thread] += ms;
896 }
898 void record_obj_copy_time(double ms) {
899 record_obj_copy_time(0, ms);
900 }
902 void record_termination_time(int thread, double ms) {
903 _par_last_termination_times_ms[thread] = ms;
904 }
906 void record_termination_time(double ms) {
907 record_termination_time(0, ms);
908 }
910 void record_pause_time_ms(double ms) {
911 _last_pause_time_ms = ms;
912 }
914 void record_clear_ct_time(double ms) {
915 _cur_clear_ct_time_ms = ms;
916 }
918 void record_par_time(double ms) {
919 _cur_collection_par_time_ms = ms;
920 }
922 void record_aux_start_time(int i) {
923 guarantee(i < _aux_num, "should be within range");
924 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
925 }
927 void record_aux_end_time(int i) {
928 guarantee(i < _aux_num, "should be within range");
929 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
930 _cur_aux_times_set[i] = true;
931 _cur_aux_times_ms[i] += ms;
932 }
934 // Record the fact that "bytes" bytes allocated in a region.
935 void record_before_bytes(size_t bytes);
936 void record_after_bytes(size_t bytes);
938 // Returns "true" if this is a good time to do a collection pause.
939 // The "word_size" argument, if non-zero, indicates the size of an
940 // allocation request that is prompting this query.
941 virtual bool should_do_collection_pause(size_t word_size) = 0;
943 // Choose a new collection set. Marks the chosen regions as being
944 // "in_collection_set", and links them together. The head and number of
945 // the collection set are available via access methods.
946 virtual void choose_collection_set() = 0;
948 void clear_collection_set() { _collection_set = NULL; }
950 // The head of the list (via "next_in_collection_set()") representing the
951 // current collection set.
952 HeapRegion* collection_set() { return _collection_set; }
954 // The number of elements in the current collection set.
955 size_t collection_set_size() { return _collection_set_size; }
957 // Add "hr" to the CS.
958 void add_to_collection_set(HeapRegion* hr);
960 bool should_initiate_conc_mark() { return _should_initiate_conc_mark; }
961 void set_should_initiate_conc_mark() { _should_initiate_conc_mark = true; }
962 void unset_should_initiate_conc_mark(){ _should_initiate_conc_mark = false; }
964 void checkpoint_conc_overhead();
966 // If an expansion would be appropriate, because recent GC overhead had
967 // exceeded the desired limit, return an amount to expand by.
968 virtual size_t expansion_amount();
970 // note start of mark thread
971 void note_start_of_mark_thread();
973 // The marked bytes of the "r" has changed; reclassify it's desirability
974 // for marking. Also asserts that "r" is eligible for a CS.
975 virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
977 #ifndef PRODUCT
978 // Check any appropriate marked bytes info, asserting false if
979 // something's wrong, else returning "true".
980 virtual bool assertMarkedBytesDataOK() = 0;
981 #endif
983 // Print tracing information.
984 void print_tracing_info() const;
986 // Print stats on young survival ratio
987 void print_yg_surv_rate_info() const;
989 void finished_recalculating_age_indexes(bool is_survivors) {
990 if (is_survivors) {
991 _survivor_surv_rate_group->finished_recalculating_age_indexes();
992 } else {
993 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
994 }
995 // do that for any other surv rate groups
996 }
998 bool should_add_next_region_to_young_list();
1000 bool in_young_gc_mode() {
1001 return _in_young_gc_mode;
1002 }
1003 void set_in_young_gc_mode(bool in_young_gc_mode) {
1004 _in_young_gc_mode = in_young_gc_mode;
1005 }
1007 bool full_young_gcs() {
1008 return _full_young_gcs;
1009 }
1010 void set_full_young_gcs(bool full_young_gcs) {
1011 _full_young_gcs = full_young_gcs;
1012 }
1014 bool adaptive_young_list_length() {
1015 return _adaptive_young_list_length;
1016 }
1017 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1018 _adaptive_young_list_length = adaptive_young_list_length;
1019 }
1021 inline double get_gc_eff_factor() {
1022 double ratio = _known_garbage_ratio;
1024 double square = ratio * ratio;
1025 // square = square * square;
1026 double ret = square * 9.0 + 1.0;
1027 #if 0
1028 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1029 #endif // 0
1030 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1031 return ret;
1032 }
1034 //
1035 // Survivor regions policy.
1036 //
1037 protected:
1039 // Current tenuring threshold, set to 0 if the collector reaches the
1040 // maximum amount of suvivors regions.
1041 int _tenuring_threshold;
1043 // The limit on the number of regions allocated for survivors.
1044 size_t _max_survivor_regions;
1046 // The amount of survor regions after a collection.
1047 size_t _recorded_survivor_regions;
1048 // List of survivor regions.
1049 HeapRegion* _recorded_survivor_head;
1050 HeapRegion* _recorded_survivor_tail;
1052 ageTable _survivors_age_table;
1054 public:
1056 inline GCAllocPurpose
1057 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1058 if (age < _tenuring_threshold && src_region->is_young()) {
1059 return GCAllocForSurvived;
1060 } else {
1061 return GCAllocForTenured;
1062 }
1063 }
1065 inline bool track_object_age(GCAllocPurpose purpose) {
1066 return purpose == GCAllocForSurvived;
1067 }
1069 inline GCAllocPurpose alternative_purpose(int purpose) {
1070 return GCAllocForTenured;
1071 }
1073 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1075 size_t max_regions(int purpose);
1077 // The limit on regions for a particular purpose is reached.
1078 void note_alloc_region_limit_reached(int purpose) {
1079 if (purpose == GCAllocForSurvived) {
1080 _tenuring_threshold = 0;
1081 }
1082 }
1084 void note_start_adding_survivor_regions() {
1085 _survivor_surv_rate_group->start_adding_regions();
1086 }
1088 void note_stop_adding_survivor_regions() {
1089 _survivor_surv_rate_group->stop_adding_regions();
1090 }
1092 void record_survivor_regions(size_t regions,
1093 HeapRegion* head,
1094 HeapRegion* tail) {
1095 _recorded_survivor_regions = regions;
1096 _recorded_survivor_head = head;
1097 _recorded_survivor_tail = tail;
1098 }
1100 size_t recorded_survivor_regions() {
1101 return _recorded_survivor_regions;
1102 }
1104 void record_thread_age_table(ageTable* age_table)
1105 {
1106 _survivors_age_table.merge_par(age_table);
1107 }
1109 // Calculates survivor space parameters.
1110 void calculate_survivors_policy();
1112 };
1114 // This encapsulates a particular strategy for a g1 Collector.
1115 //
1116 // Start a concurrent mark when our heap size is n bytes
1117 // greater then our heap size was at the last concurrent
1118 // mark. Where n is a function of the CMSTriggerRatio
1119 // and the MinHeapFreeRatio.
1120 //
1121 // Start a g1 collection pause when we have allocated the
1122 // average number of bytes currently being freed in
1123 // a collection, but only if it is at least one region
1124 // full
1125 //
1126 // Resize Heap based on desired
1127 // allocation space, where desired allocation space is
1128 // a function of survival rate and desired future to size.
1129 //
1130 // Choose collection set by first picking all older regions
1131 // which have a survival rate which beats our projected young
1132 // survival rate. Then fill out the number of needed regions
1133 // with young regions.
1135 class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
1136 CollectionSetChooser* _collectionSetChooser;
1137 // If the estimated is less then desirable, resize if possible.
1138 void expand_if_possible(size_t numRegions);
1140 virtual void choose_collection_set();
1141 virtual void record_collection_pause_start(double start_time_sec,
1142 size_t start_used);
1143 virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
1144 size_t max_live_bytes);
1145 virtual void record_full_collection_end();
1147 public:
1148 G1CollectorPolicy_BestRegionsFirst() {
1149 _collectionSetChooser = new CollectionSetChooser();
1150 }
1151 void record_collection_pause_end(bool abandoned);
1152 bool should_do_collection_pause(size_t word_size);
1153 // This is not needed any more, after the CSet choosing code was
1154 // changed to use the pause prediction work. But let's leave the
1155 // hook in just in case.
1156 void note_change_in_marked_bytes(HeapRegion* r) { }
1157 #ifndef PRODUCT
1158 bool assertMarkedBytesDataOK();
1159 #endif
1160 };
1162 // This should move to some place more general...
1164 // If we have "n" measurements, and we've kept track of their "sum" and the
1165 // "sum_of_squares" of the measurements, this returns the variance of the
1166 // sequence.
1167 inline double variance(int n, double sum_of_squares, double sum) {
1168 double n_d = (double)n;
1169 double avg = sum/n_d;
1170 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1171 }
1173 // Local Variables: ***
1174 // c-indentation-style: gnu ***
1175 // End: ***