Mon, 12 Mar 2012 14:59:00 -0700
7147724: G1: hang in SurrogateLockerThread::manipulatePLL
Summary: Attempting to initiate a marking cycle when allocating a humongous object can, if a marking cycle is successfully initiated by another thread, result in the allocating thread spinning until the marking cycle is complete. Eliminate a deadlock between the main ConcurrentMarkThread, the SurrogateLocker thread, the VM thread, and a mutator thread waiting on the SecondaryFreeList_lock (while free regions are going to become available) by not manipulating the pending list lock during the prologue and epilogue of the cleanup pause.
Reviewed-by: brutisso, jcoomes, tonyp
1 /*
2 * Copyright (c) 2001, 2012, 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
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7 * published by the Free Software Foundation.
8 *
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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 *
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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(root_region_scan_wait)
69 define_num_seq(parallel) // parallel only
70 define_num_seq(ext_root_scan)
71 define_num_seq(satb_filtering)
72 define_num_seq(update_rs)
73 define_num_seq(scan_rs)
74 define_num_seq(obj_copy)
75 define_num_seq(termination) // parallel only
76 define_num_seq(parallel_other) // parallel only
77 define_num_seq(mark_closure)
78 define_num_seq(clear_ct)
79 };
81 class Summary: public PauseSummary,
82 public MainBodySummary {
83 public:
84 virtual MainBodySummary* main_body_summary() { return this; }
85 };
87 // There are three command line options related to the young gen size:
88 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
89 // just a short form for NewSize==MaxNewSize). G1 will use its internal
90 // heuristics to calculate the actual young gen size, so these options
91 // basically only limit the range within which G1 can pick a young gen
92 // size. Also, these are general options taking byte sizes. G1 will
93 // internally work with a number of regions instead. So, some rounding
94 // will occur.
95 //
96 // If nothing related to the the young gen size is set on the command
97 // line we should allow the young gen to be between
98 // G1DefaultMinNewGenPercent and G1DefaultMaxNewGenPercent of the
99 // heap size. This means that every time the heap size changes the
100 // limits for the young gen size will be updated.
101 //
102 // If only -XX:NewSize is set we should use the specified value as the
103 // minimum size for young gen. Still using G1DefaultMaxNewGenPercent
104 // of the heap as maximum.
105 //
106 // If only -XX:MaxNewSize is set we should use the specified value as the
107 // maximum size for young gen. Still using G1DefaultMinNewGenPercent
108 // of the heap as minimum.
109 //
110 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
111 // No updates when the heap size changes. There is a special case when
112 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
113 // different heuristic for calculating the collection set when we do mixed
114 // collection.
115 //
116 // If only -XX:NewRatio is set we should use the specified ratio of the heap
117 // as both min and max. This will be interpreted as "fixed" just like the
118 // NewSize==MaxNewSize case above. But we will update the min and max
119 // everytime the heap size changes.
120 //
121 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
122 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
123 class G1YoungGenSizer : public CHeapObj {
124 private:
125 enum SizerKind {
126 SizerDefaults,
127 SizerNewSizeOnly,
128 SizerMaxNewSizeOnly,
129 SizerMaxAndNewSize,
130 SizerNewRatio
131 };
132 SizerKind _sizer_kind;
133 size_t _min_desired_young_length;
134 size_t _max_desired_young_length;
135 bool _adaptive_size;
136 size_t calculate_default_min_length(size_t new_number_of_heap_regions);
137 size_t calculate_default_max_length(size_t new_number_of_heap_regions);
139 public:
140 G1YoungGenSizer();
141 void heap_size_changed(size_t new_number_of_heap_regions);
142 size_t min_desired_young_length() {
143 return _min_desired_young_length;
144 }
145 size_t max_desired_young_length() {
146 return _max_desired_young_length;
147 }
148 bool adaptive_young_list_length() {
149 return _adaptive_size;
150 }
151 };
153 class G1CollectorPolicy: public CollectorPolicy {
154 private:
155 // either equal to the number of parallel threads, if ParallelGCThreads
156 // has been set, or 1 otherwise
157 int _parallel_gc_threads;
159 // The number of GC threads currently active.
160 uintx _no_of_gc_threads;
162 enum SomePrivateConstants {
163 NumPrevPausesForHeuristics = 10
164 };
166 G1MMUTracker* _mmu_tracker;
168 void initialize_flags();
170 void initialize_all() {
171 initialize_flags();
172 initialize_size_info();
173 initialize_perm_generation(PermGen::MarkSweepCompact);
174 }
176 CollectionSetChooser* _collectionSetChooser;
178 double _cur_collection_start_sec;
179 size_t _cur_collection_pause_used_at_start_bytes;
180 size_t _cur_collection_pause_used_regions_at_start;
181 double _cur_collection_par_time_ms;
182 double _cur_satb_drain_time_ms;
183 double _cur_clear_ct_time_ms;
184 double _cur_ref_proc_time_ms;
185 double _cur_ref_enq_time_ms;
187 #ifndef PRODUCT
188 // Card Table Count Cache stats
189 double _min_clear_cc_time_ms; // min
190 double _max_clear_cc_time_ms; // max
191 double _cur_clear_cc_time_ms; // clearing time during current pause
192 double _cum_clear_cc_time_ms; // cummulative clearing time
193 jlong _num_cc_clears; // number of times the card count cache has been cleared
194 #endif
196 // These exclude marking times.
197 TruncatedSeq* _recent_gc_times_ms;
199 TruncatedSeq* _concurrent_mark_remark_times_ms;
200 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
202 Summary* _summary;
204 NumberSeq* _all_pause_times_ms;
205 NumberSeq* _all_full_gc_times_ms;
206 double _stop_world_start;
207 NumberSeq* _all_stop_world_times_ms;
208 NumberSeq* _all_yield_times_ms;
210 int _aux_num;
211 NumberSeq* _all_aux_times_ms;
212 double* _cur_aux_start_times_ms;
213 double* _cur_aux_times_ms;
214 bool* _cur_aux_times_set;
216 double* _par_last_gc_worker_start_times_ms;
217 double* _par_last_ext_root_scan_times_ms;
218 double* _par_last_satb_filtering_times_ms;
219 double* _par_last_update_rs_times_ms;
220 double* _par_last_update_rs_processed_buffers;
221 double* _par_last_scan_rs_times_ms;
222 double* _par_last_obj_copy_times_ms;
223 double* _par_last_termination_times_ms;
224 double* _par_last_termination_attempts;
225 double* _par_last_gc_worker_end_times_ms;
226 double* _par_last_gc_worker_times_ms;
228 // Each workers 'other' time i.e. the elapsed time of the parallel
229 // phase of the pause minus the sum of the individual sub-phase
230 // times for a given worker thread.
231 double* _par_last_gc_worker_other_times_ms;
233 // indicates whether we are in young or mixed GC mode
234 bool _gcs_are_young;
236 size_t _young_list_target_length;
237 size_t _young_list_fixed_length;
238 size_t _prev_eden_capacity; // used for logging
240 // The max number of regions we can extend the eden by while the GC
241 // locker is active. This should be >= _young_list_target_length;
242 size_t _young_list_max_length;
244 bool _last_gc_was_young;
246 unsigned _young_pause_num;
247 unsigned _mixed_pause_num;
249 bool _during_marking;
250 bool _in_marking_window;
251 bool _in_marking_window_im;
253 SurvRateGroup* _short_lived_surv_rate_group;
254 SurvRateGroup* _survivor_surv_rate_group;
255 // add here any more surv rate groups
257 double _gc_overhead_perc;
259 double _reserve_factor;
260 size_t _reserve_regions;
262 bool during_marking() {
263 return _during_marking;
264 }
266 private:
267 enum PredictionConstants {
268 TruncatedSeqLength = 10
269 };
271 TruncatedSeq* _alloc_rate_ms_seq;
272 double _prev_collection_pause_end_ms;
274 TruncatedSeq* _pending_card_diff_seq;
275 TruncatedSeq* _rs_length_diff_seq;
276 TruncatedSeq* _cost_per_card_ms_seq;
277 TruncatedSeq* _young_cards_per_entry_ratio_seq;
278 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
279 TruncatedSeq* _cost_per_entry_ms_seq;
280 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
281 TruncatedSeq* _cost_per_byte_ms_seq;
282 TruncatedSeq* _constant_other_time_ms_seq;
283 TruncatedSeq* _young_other_cost_per_region_ms_seq;
284 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
286 TruncatedSeq* _pending_cards_seq;
287 TruncatedSeq* _rs_lengths_seq;
289 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
291 TruncatedSeq* _young_gc_eff_seq;
293 G1YoungGenSizer* _young_gen_sizer;
295 size_t _eden_cset_region_length;
296 size_t _survivor_cset_region_length;
297 size_t _old_cset_region_length;
299 void init_cset_region_lengths(size_t eden_cset_region_length,
300 size_t survivor_cset_region_length);
302 size_t eden_cset_region_length() { return _eden_cset_region_length; }
303 size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
304 size_t old_cset_region_length() { return _old_cset_region_length; }
306 size_t _free_regions_at_end_of_collection;
308 size_t _recorded_rs_lengths;
309 size_t _max_rs_lengths;
311 double _recorded_young_free_cset_time_ms;
312 double _recorded_non_young_free_cset_time_ms;
314 double _sigma;
316 size_t _rs_lengths_prediction;
318 size_t _known_garbage_bytes;
319 double _known_garbage_ratio;
321 double sigma() { return _sigma; }
323 // A function that prevents us putting too much stock in small sample
324 // sets. Returns a number between 2.0 and 1.0, depending on the number
325 // of samples. 5 or more samples yields one; fewer scales linearly from
326 // 2.0 at 1 sample to 1.0 at 5.
327 double confidence_factor(int samples) {
328 if (samples > 4) return 1.0;
329 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
330 }
332 double get_new_neg_prediction(TruncatedSeq* seq) {
333 return seq->davg() - sigma() * seq->dsd();
334 }
336 #ifndef PRODUCT
337 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
338 #endif // PRODUCT
340 void adjust_concurrent_refinement(double update_rs_time,
341 double update_rs_processed_buffers,
342 double goal_ms);
344 uintx no_of_gc_threads() { return _no_of_gc_threads; }
345 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
347 double _pause_time_target_ms;
348 double _recorded_young_cset_choice_time_ms;
349 double _recorded_non_young_cset_choice_time_ms;
350 size_t _pending_cards;
351 size_t _max_pending_cards;
353 public:
354 // Accessors
356 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
357 hr->set_young();
358 hr->install_surv_rate_group(_short_lived_surv_rate_group);
359 hr->set_young_index_in_cset(young_index_in_cset);
360 }
362 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
363 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
364 hr->install_surv_rate_group(_survivor_surv_rate_group);
365 hr->set_young_index_in_cset(young_index_in_cset);
366 }
368 #ifndef PRODUCT
369 bool verify_young_ages();
370 #endif // PRODUCT
372 double get_new_prediction(TruncatedSeq* seq) {
373 return MAX2(seq->davg() + sigma() * seq->dsd(),
374 seq->davg() * confidence_factor(seq->num()));
375 }
377 void record_max_rs_lengths(size_t rs_lengths) {
378 _max_rs_lengths = rs_lengths;
379 }
381 size_t predict_pending_card_diff() {
382 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
383 if (prediction < 0.00001) {
384 return 0;
385 } else {
386 return (size_t) prediction;
387 }
388 }
390 size_t predict_pending_cards() {
391 size_t max_pending_card_num = _g1->max_pending_card_num();
392 size_t diff = predict_pending_card_diff();
393 size_t prediction;
394 if (diff > max_pending_card_num) {
395 prediction = max_pending_card_num;
396 } else {
397 prediction = max_pending_card_num - diff;
398 }
400 return prediction;
401 }
403 size_t predict_rs_length_diff() {
404 return (size_t) get_new_prediction(_rs_length_diff_seq);
405 }
407 double predict_alloc_rate_ms() {
408 return get_new_prediction(_alloc_rate_ms_seq);
409 }
411 double predict_cost_per_card_ms() {
412 return get_new_prediction(_cost_per_card_ms_seq);
413 }
415 double predict_rs_update_time_ms(size_t pending_cards) {
416 return (double) pending_cards * predict_cost_per_card_ms();
417 }
419 double predict_young_cards_per_entry_ratio() {
420 return get_new_prediction(_young_cards_per_entry_ratio_seq);
421 }
423 double predict_mixed_cards_per_entry_ratio() {
424 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
425 return predict_young_cards_per_entry_ratio();
426 } else {
427 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
428 }
429 }
431 size_t predict_young_card_num(size_t rs_length) {
432 return (size_t) ((double) rs_length *
433 predict_young_cards_per_entry_ratio());
434 }
436 size_t predict_non_young_card_num(size_t rs_length) {
437 return (size_t) ((double) rs_length *
438 predict_mixed_cards_per_entry_ratio());
439 }
441 double predict_rs_scan_time_ms(size_t card_num) {
442 if (gcs_are_young()) {
443 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
444 } else {
445 return predict_mixed_rs_scan_time_ms(card_num);
446 }
447 }
449 double predict_mixed_rs_scan_time_ms(size_t card_num) {
450 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
451 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
452 } else {
453 return (double) (card_num *
454 get_new_prediction(_mixed_cost_per_entry_ms_seq));
455 }
456 }
458 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
459 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
460 return (1.1 * (double) bytes_to_copy) *
461 get_new_prediction(_cost_per_byte_ms_seq);
462 } else {
463 return (double) bytes_to_copy *
464 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
465 }
466 }
468 double predict_object_copy_time_ms(size_t bytes_to_copy) {
469 if (_in_marking_window && !_in_marking_window_im) {
470 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
471 } else {
472 return (double) bytes_to_copy *
473 get_new_prediction(_cost_per_byte_ms_seq);
474 }
475 }
477 double predict_constant_other_time_ms() {
478 return get_new_prediction(_constant_other_time_ms_seq);
479 }
481 double predict_young_other_time_ms(size_t young_num) {
482 return (double) young_num *
483 get_new_prediction(_young_other_cost_per_region_ms_seq);
484 }
486 double predict_non_young_other_time_ms(size_t non_young_num) {
487 return (double) non_young_num *
488 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
489 }
491 double predict_young_collection_elapsed_time_ms(size_t adjustment);
492 double predict_base_elapsed_time_ms(size_t pending_cards);
493 double predict_base_elapsed_time_ms(size_t pending_cards,
494 size_t scanned_cards);
495 size_t predict_bytes_to_copy(HeapRegion* hr);
496 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
498 void set_recorded_rs_lengths(size_t rs_lengths);
500 size_t cset_region_length() { return young_cset_region_length() +
501 old_cset_region_length(); }
502 size_t young_cset_region_length() { return eden_cset_region_length() +
503 survivor_cset_region_length(); }
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 void cset_regions_freed() {
520 bool propagate = _last_gc_was_young && !_in_marking_window;
521 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
522 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
523 // also call it on any more surv rate groups
524 }
526 void set_known_garbage_bytes(size_t known_garbage_bytes) {
527 _known_garbage_bytes = known_garbage_bytes;
528 size_t heap_bytes = _g1->capacity();
529 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
530 }
532 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
533 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
535 _known_garbage_bytes -= known_garbage_bytes;
536 size_t heap_bytes = _g1->capacity();
537 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
538 }
540 G1MMUTracker* mmu_tracker() {
541 return _mmu_tracker;
542 }
544 double max_pause_time_ms() {
545 return _mmu_tracker->max_gc_time() * 1000.0;
546 }
548 double predict_remark_time_ms() {
549 return get_new_prediction(_concurrent_mark_remark_times_ms);
550 }
552 double predict_cleanup_time_ms() {
553 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
554 }
556 // Returns an estimate of the survival rate of the region at yg-age
557 // "yg_age".
558 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
559 TruncatedSeq* seq = surv_rate_group->get_seq(age);
560 if (seq->num() == 0)
561 gclog_or_tty->print("BARF! age is %d", age);
562 guarantee( seq->num() > 0, "invariant" );
563 double pred = get_new_prediction(seq);
564 if (pred > 1.0)
565 pred = 1.0;
566 return pred;
567 }
569 double predict_yg_surv_rate(int age) {
570 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
571 }
573 double accum_yg_surv_rate_pred(int age) {
574 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
575 }
577 private:
578 void print_stats(int level, const char* str, double value);
579 void print_stats(int level, const char* str, int value);
581 void print_par_stats(int level, const char* str, double* data);
582 void print_par_sizes(int level, const char* str, double* data);
584 void check_other_times(int level,
585 NumberSeq* other_times_ms,
586 NumberSeq* calc_other_times_ms) const;
588 void print_summary (PauseSummary* stats) const;
590 void print_summary (int level, const char* str, NumberSeq* seq) const;
591 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
593 double avg_value (double* data);
594 double max_value (double* data);
595 double sum_of_values (double* data);
596 double max_sum (double* data1, double* data2);
598 double _last_pause_time_ms;
600 size_t _bytes_in_collection_set_before_gc;
601 size_t _bytes_copied_during_gc;
603 // Used to count used bytes in CS.
604 friend class CountCSClosure;
606 // Statistics kept per GC stoppage, pause or full.
607 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
609 // Add a new GC of the given duration and end time to the record.
610 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
612 // The head of the list (via "next_in_collection_set()") representing the
613 // current collection set. Set from the incrementally built collection
614 // set at the start of the pause.
615 HeapRegion* _collection_set;
617 // The number of bytes in the collection set before the pause. Set from
618 // the incrementally built collection set at the start of an evacuation
619 // pause.
620 size_t _collection_set_bytes_used_before;
622 // The associated information that is maintained while the incremental
623 // collection set is being built with young regions. Used to populate
624 // the recorded info for the evacuation pause.
626 enum CSetBuildType {
627 Active, // We are actively building the collection set
628 Inactive // We are not actively building the collection set
629 };
631 CSetBuildType _inc_cset_build_state;
633 // The head of the incrementally built collection set.
634 HeapRegion* _inc_cset_head;
636 // The tail of the incrementally built collection set.
637 HeapRegion* _inc_cset_tail;
639 // The number of bytes in the incrementally built collection set.
640 // Used to set _collection_set_bytes_used_before at the start of
641 // an evacuation pause.
642 size_t _inc_cset_bytes_used_before;
644 // Used to record the highest end of heap region in collection set
645 HeapWord* _inc_cset_max_finger;
647 // The RSet lengths recorded for regions in the CSet. It is updated
648 // by the thread that adds a new region to the CSet. We assume that
649 // only one thread can be allocating a new CSet region (currently,
650 // it does so after taking the Heap_lock) hence no need to
651 // synchronize updates to this field.
652 size_t _inc_cset_recorded_rs_lengths;
654 // A concurrent refinement thread periodcially samples the young
655 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
656 // the RSets grow. Instead of having to syncronize updates to that
657 // field we accumulate them in this field and add it to
658 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
659 ssize_t _inc_cset_recorded_rs_lengths_diffs;
661 // The predicted elapsed time it will take to collect the regions in
662 // the CSet. This is updated by the thread that adds a new region to
663 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
664 // MT-safety assumptions.
665 double _inc_cset_predicted_elapsed_time_ms;
667 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
668 double _inc_cset_predicted_elapsed_time_ms_diffs;
670 // Stash a pointer to the g1 heap.
671 G1CollectedHeap* _g1;
673 // The ratio of gc time to elapsed time, computed over recent pauses.
674 double _recent_avg_pause_time_ratio;
676 double recent_avg_pause_time_ratio() {
677 return _recent_avg_pause_time_ratio;
678 }
680 // At the end of a pause we check the heap occupancy and we decide
681 // whether we will start a marking cycle during the next pause. If
682 // we decide that we want to do that, we will set this parameter to
683 // true. So, this parameter will stay true between the end of a
684 // pause and the beginning of a subsequent pause (not necessarily
685 // the next one, see the comments on the next field) when we decide
686 // that we will indeed start a marking cycle and do the initial-mark
687 // work.
688 volatile bool _initiate_conc_mark_if_possible;
690 // If initiate_conc_mark_if_possible() is set at the beginning of a
691 // pause, it is a suggestion that the pause should start a marking
692 // cycle by doing the initial-mark work. However, it is possible
693 // that the concurrent marking thread is still finishing up the
694 // previous marking cycle (e.g., clearing the next marking
695 // bitmap). If that is the case we cannot start a new cycle and
696 // we'll have to wait for the concurrent marking thread to finish
697 // what it is doing. In this case we will postpone the marking cycle
698 // initiation decision for the next pause. When we eventually decide
699 // to start a cycle, we will set _during_initial_mark_pause which
700 // will stay true until the end of the initial-mark pause and it's
701 // the condition that indicates that a pause is doing the
702 // initial-mark work.
703 volatile bool _during_initial_mark_pause;
705 bool _last_young_gc;
707 // This set of variables tracks the collector efficiency, in order to
708 // determine whether we should initiate a new marking.
709 double _cur_mark_stop_world_time_ms;
710 double _mark_remark_start_sec;
711 double _mark_cleanup_start_sec;
712 double _mark_closure_time_ms;
713 double _root_region_scan_wait_time_ms;
715 // Update the young list target length either by setting it to the
716 // desired fixed value or by calculating it using G1's pause
717 // prediction model. If no rs_lengths parameter is passed, predict
718 // the RS lengths using the prediction model, otherwise use the
719 // given rs_lengths as the prediction.
720 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
722 // Calculate and return the minimum desired young list target
723 // length. This is the minimum desired young list length according
724 // to the user's inputs.
725 size_t calculate_young_list_desired_min_length(size_t base_min_length);
727 // Calculate and return the maximum desired young list target
728 // length. This is the maximum desired young list length according
729 // to the user's inputs.
730 size_t calculate_young_list_desired_max_length();
732 // Calculate and return the maximum young list target length that
733 // can fit into the pause time goal. The parameters are: rs_lengths
734 // represent the prediction of how large the young RSet lengths will
735 // be, base_min_length is the alreay existing number of regions in
736 // the young list, min_length and max_length are the desired min and
737 // max young list length according to the user's inputs.
738 size_t calculate_young_list_target_length(size_t rs_lengths,
739 size_t base_min_length,
740 size_t desired_min_length,
741 size_t desired_max_length);
743 // Check whether a given young length (young_length) fits into the
744 // given target pause time and whether the prediction for the amount
745 // of objects to be copied for the given length will fit into the
746 // given free space (expressed by base_free_regions). It is used by
747 // calculate_young_list_target_length().
748 bool predict_will_fit(size_t young_length, double base_time_ms,
749 size_t base_free_regions, double target_pause_time_ms);
751 // Count the number of bytes used in the CS.
752 void count_CS_bytes_used();
754 public:
756 G1CollectorPolicy();
758 virtual G1CollectorPolicy* as_g1_policy() { return this; }
760 virtual CollectorPolicy::Name kind() {
761 return CollectorPolicy::G1CollectorPolicyKind;
762 }
764 // Check the current value of the young list RSet lengths and
765 // compare it against the last prediction. If the current value is
766 // higher, recalculate the young list target length prediction.
767 void revise_young_list_target_length_if_necessary();
769 size_t bytes_in_collection_set() {
770 return _bytes_in_collection_set_before_gc;
771 }
773 unsigned calc_gc_alloc_time_stamp() {
774 return _all_pause_times_ms->num() + 1;
775 }
777 // This should be called after the heap is resized.
778 void record_new_heap_size(size_t new_number_of_regions);
780 void init();
782 // Create jstat counters for the policy.
783 virtual void initialize_gc_policy_counters();
785 virtual HeapWord* mem_allocate_work(size_t size,
786 bool is_tlab,
787 bool* gc_overhead_limit_was_exceeded);
789 // This method controls how a collector handles one or more
790 // of its generations being fully allocated.
791 virtual HeapWord* satisfy_failed_allocation(size_t size,
792 bool is_tlab);
794 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
796 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
798 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
800 // Update the heuristic info to record a collection pause of the given
801 // start time, where the given number of bytes were used at the start.
802 // This may involve changing the desired size of a collection set.
804 void record_stop_world_start();
806 void record_collection_pause_start(double start_time_sec, size_t start_used);
808 // Must currently be called while the world is stopped.
809 void record_concurrent_mark_init_end(double
810 mark_init_elapsed_time_ms);
812 void record_mark_closure_time(double mark_closure_time_ms) {
813 _mark_closure_time_ms = mark_closure_time_ms;
814 }
816 void record_root_region_scan_wait_time(double time_ms) {
817 _root_region_scan_wait_time_ms = time_ms;
818 }
820 void record_concurrent_mark_remark_start();
821 void record_concurrent_mark_remark_end();
823 void record_concurrent_mark_cleanup_start();
824 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
825 void record_concurrent_mark_cleanup_completed();
827 void record_concurrent_pause();
828 void record_concurrent_pause_end();
830 void record_collection_pause_end(int no_of_gc_threads);
831 void print_heap_transition();
833 // Record the fact that a full collection occurred.
834 void record_full_collection_start();
835 void record_full_collection_end();
837 void record_gc_worker_start_time(int worker_i, double ms) {
838 _par_last_gc_worker_start_times_ms[worker_i] = ms;
839 }
841 void record_ext_root_scan_time(int worker_i, double ms) {
842 _par_last_ext_root_scan_times_ms[worker_i] = ms;
843 }
845 void record_satb_filtering_time(int worker_i, double ms) {
846 _par_last_satb_filtering_times_ms[worker_i] = ms;
847 }
849 void record_satb_drain_time(double ms) {
850 assert(_g1->mark_in_progress(), "shouldn't be here otherwise");
851 _cur_satb_drain_time_ms = ms;
852 }
854 void record_update_rs_time(int thread, double ms) {
855 _par_last_update_rs_times_ms[thread] = ms;
856 }
858 void record_update_rs_processed_buffers (int thread,
859 double processed_buffers) {
860 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
861 }
863 void record_scan_rs_time(int thread, double ms) {
864 _par_last_scan_rs_times_ms[thread] = ms;
865 }
867 void reset_obj_copy_time(int thread) {
868 _par_last_obj_copy_times_ms[thread] = 0.0;
869 }
871 void reset_obj_copy_time() {
872 reset_obj_copy_time(0);
873 }
875 void record_obj_copy_time(int thread, double ms) {
876 _par_last_obj_copy_times_ms[thread] += ms;
877 }
879 void record_termination(int thread, double ms, size_t attempts) {
880 _par_last_termination_times_ms[thread] = ms;
881 _par_last_termination_attempts[thread] = (double) attempts;
882 }
884 void record_gc_worker_end_time(int worker_i, double ms) {
885 _par_last_gc_worker_end_times_ms[worker_i] = ms;
886 }
888 void record_pause_time_ms(double ms) {
889 _last_pause_time_ms = ms;
890 }
892 void record_clear_ct_time(double ms) {
893 _cur_clear_ct_time_ms = ms;
894 }
896 void record_par_time(double ms) {
897 _cur_collection_par_time_ms = ms;
898 }
900 void record_aux_start_time(int i) {
901 guarantee(i < _aux_num, "should be within range");
902 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
903 }
905 void record_aux_end_time(int i) {
906 guarantee(i < _aux_num, "should be within range");
907 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
908 _cur_aux_times_set[i] = true;
909 _cur_aux_times_ms[i] += ms;
910 }
912 void record_ref_proc_time(double ms) {
913 _cur_ref_proc_time_ms = ms;
914 }
916 void record_ref_enq_time(double ms) {
917 _cur_ref_enq_time_ms = ms;
918 }
920 #ifndef PRODUCT
921 void record_cc_clear_time(double ms) {
922 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
923 _min_clear_cc_time_ms = ms;
924 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
925 _max_clear_cc_time_ms = ms;
926 _cur_clear_cc_time_ms = ms;
927 _cum_clear_cc_time_ms += ms;
928 _num_cc_clears++;
929 }
930 #endif
932 // Record how much space we copied during a GC. This is typically
933 // called when a GC alloc region is being retired.
934 void record_bytes_copied_during_gc(size_t bytes) {
935 _bytes_copied_during_gc += bytes;
936 }
938 // The amount of space we copied during a GC.
939 size_t bytes_copied_during_gc() {
940 return _bytes_copied_during_gc;
941 }
943 // Determine whether the next GC should be mixed. Called to determine
944 // whether to start mixed GCs or whether to carry on doing mixed
945 // GCs. The two action strings are used in the ergo output when the
946 // method returns true or false.
947 bool next_gc_should_be_mixed(const char* true_action_str,
948 const char* false_action_str);
950 // Choose a new collection set. Marks the chosen regions as being
951 // "in_collection_set", and links them together. The head and number of
952 // the collection set are available via access methods.
953 void finalize_cset(double target_pause_time_ms);
955 // The head of the list (via "next_in_collection_set()") representing the
956 // current collection set.
957 HeapRegion* collection_set() { return _collection_set; }
959 void clear_collection_set() { _collection_set = NULL; }
961 // Add old region "hr" to the CSet.
962 void add_old_region_to_cset(HeapRegion* hr);
964 // Incremental CSet Support
966 // The head of the incrementally built collection set.
967 HeapRegion* inc_cset_head() { return _inc_cset_head; }
969 // The tail of the incrementally built collection set.
970 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
972 // Initialize incremental collection set info.
973 void start_incremental_cset_building();
975 // Perform any final calculations on the incremental CSet fields
976 // before we can use them.
977 void finalize_incremental_cset_building();
979 void clear_incremental_cset() {
980 _inc_cset_head = NULL;
981 _inc_cset_tail = NULL;
982 }
984 // Stop adding regions to the incremental collection set
985 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
987 // Add information about hr to the aggregated information for the
988 // incrementally built collection set.
989 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
991 // Update information about hr in the aggregated information for
992 // the incrementally built collection set.
993 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
995 private:
996 // Update the incremental cset information when adding a region
997 // (should not be called directly).
998 void add_region_to_incremental_cset_common(HeapRegion* hr);
1000 public:
1001 // Add hr to the LHS of the incremental collection set.
1002 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
1004 // Add hr to the RHS of the incremental collection set.
1005 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1007 #ifndef PRODUCT
1008 void print_collection_set(HeapRegion* list_head, outputStream* st);
1009 #endif // !PRODUCT
1011 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1012 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1013 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1015 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1016 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1017 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1019 // This sets the initiate_conc_mark_if_possible() flag to start a
1020 // new cycle, as long as we are not already in one. It's best if it
1021 // is called during a safepoint when the test whether a cycle is in
1022 // progress or not is stable.
1023 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
1025 // This is called at the very beginning of an evacuation pause (it
1026 // has to be the first thing that the pause does). If
1027 // initiate_conc_mark_if_possible() is true, and the concurrent
1028 // marking thread has completed its work during the previous cycle,
1029 // it will set during_initial_mark_pause() to so that the pause does
1030 // the initial-mark work and start a marking cycle.
1031 void decide_on_conc_mark_initiation();
1033 // If an expansion would be appropriate, because recent GC overhead had
1034 // exceeded the desired limit, return an amount to expand by.
1035 size_t expansion_amount();
1037 #ifndef PRODUCT
1038 // Check any appropriate marked bytes info, asserting false if
1039 // something's wrong, else returning "true".
1040 bool assertMarkedBytesDataOK();
1041 #endif
1043 // Print tracing information.
1044 void print_tracing_info() const;
1046 // Print stats on young survival ratio
1047 void print_yg_surv_rate_info() const;
1049 void finished_recalculating_age_indexes(bool is_survivors) {
1050 if (is_survivors) {
1051 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1052 } else {
1053 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1054 }
1055 // do that for any other surv rate groups
1056 }
1058 bool is_young_list_full() {
1059 size_t young_list_length = _g1->young_list()->length();
1060 size_t young_list_target_length = _young_list_target_length;
1061 return young_list_length >= young_list_target_length;
1062 }
1064 bool can_expand_young_list() {
1065 size_t young_list_length = _g1->young_list()->length();
1066 size_t young_list_max_length = _young_list_max_length;
1067 return young_list_length < young_list_max_length;
1068 }
1070 size_t young_list_max_length() {
1071 return _young_list_max_length;
1072 }
1074 bool gcs_are_young() {
1075 return _gcs_are_young;
1076 }
1077 void set_gcs_are_young(bool gcs_are_young) {
1078 _gcs_are_young = gcs_are_young;
1079 }
1081 bool adaptive_young_list_length() {
1082 return _young_gen_sizer->adaptive_young_list_length();
1083 }
1085 inline double get_gc_eff_factor() {
1086 double ratio = _known_garbage_ratio;
1088 double square = ratio * ratio;
1089 // square = square * square;
1090 double ret = square * 9.0 + 1.0;
1091 #if 0
1092 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1093 #endif // 0
1094 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1095 return ret;
1096 }
1098 private:
1099 //
1100 // Survivor regions policy.
1101 //
1103 // Current tenuring threshold, set to 0 if the collector reaches the
1104 // maximum amount of suvivors regions.
1105 int _tenuring_threshold;
1107 // The limit on the number of regions allocated for survivors.
1108 size_t _max_survivor_regions;
1110 // For reporting purposes.
1111 size_t _eden_bytes_before_gc;
1112 size_t _survivor_bytes_before_gc;
1113 size_t _capacity_before_gc;
1115 // The amount of survor regions after a collection.
1116 size_t _recorded_survivor_regions;
1117 // List of survivor regions.
1118 HeapRegion* _recorded_survivor_head;
1119 HeapRegion* _recorded_survivor_tail;
1121 ageTable _survivors_age_table;
1123 public:
1125 inline GCAllocPurpose
1126 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1127 if (age < _tenuring_threshold && src_region->is_young()) {
1128 return GCAllocForSurvived;
1129 } else {
1130 return GCAllocForTenured;
1131 }
1132 }
1134 inline bool track_object_age(GCAllocPurpose purpose) {
1135 return purpose == GCAllocForSurvived;
1136 }
1138 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1140 size_t max_regions(int purpose);
1142 // The limit on regions for a particular purpose is reached.
1143 void note_alloc_region_limit_reached(int purpose) {
1144 if (purpose == GCAllocForSurvived) {
1145 _tenuring_threshold = 0;
1146 }
1147 }
1149 void note_start_adding_survivor_regions() {
1150 _survivor_surv_rate_group->start_adding_regions();
1151 }
1153 void note_stop_adding_survivor_regions() {
1154 _survivor_surv_rate_group->stop_adding_regions();
1155 }
1157 void record_survivor_regions(size_t regions,
1158 HeapRegion* head,
1159 HeapRegion* tail) {
1160 _recorded_survivor_regions = regions;
1161 _recorded_survivor_head = head;
1162 _recorded_survivor_tail = tail;
1163 }
1165 size_t recorded_survivor_regions() {
1166 return _recorded_survivor_regions;
1167 }
1169 void record_thread_age_table(ageTable* age_table)
1170 {
1171 _survivors_age_table.merge_par(age_table);
1172 }
1174 void update_max_gc_locker_expansion();
1176 // Calculates survivor space parameters.
1177 void update_survivors_policy();
1179 };
1181 // This should move to some place more general...
1183 // If we have "n" measurements, and we've kept track of their "sum" and the
1184 // "sum_of_squares" of the measurements, this returns the variance of the
1185 // sequence.
1186 inline double variance(int n, double sum_of_squares, double sum) {
1187 double n_d = (double)n;
1188 double avg = sum/n_d;
1189 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1190 }
1192 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP