Thu, 17 Nov 2011 12:40:15 -0800
7112743: G1: Reduce overhead of marking closure during evacuation pauses
Summary: Parallelize the serial code that was used to mark objects reachable from survivor objects in the collection set. Some minor improvments in the timers used to track the freeing of the collection set along with some tweaks to PrintGCDetails.
Reviewed-by: tonyp, brutisso
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
28 #include "gc_implementation/g1/collectionSetChooser.hpp"
29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 #include "memory/collectorPolicy.hpp"
32 // A G1CollectorPolicy makes policy decisions that determine the
33 // characteristics of the collector. Examples include:
34 // * choice of collection set.
35 // * when to collect.
37 class HeapRegion;
38 class CollectionSetChooser;
40 // Yes, this is a bit unpleasant... but it saves replicating the same thing
41 // over and over again and introducing subtle problems through small typos and
42 // cutting and pasting mistakes. The macros below introduces a number
43 // sequnce into the following two classes and the methods that access it.
45 #define define_num_seq(name) \
46 private: \
47 NumberSeq _all_##name##_times_ms; \
48 public: \
49 void record_##name##_time_ms(double ms) { \
50 _all_##name##_times_ms.add(ms); \
51 } \
52 NumberSeq* get_##name##_seq() { \
53 return &_all_##name##_times_ms; \
54 }
56 class MainBodySummary;
58 class PauseSummary: public CHeapObj {
59 define_num_seq(total)
60 define_num_seq(other)
62 public:
63 virtual MainBodySummary* main_body_summary() { return NULL; }
64 };
66 class MainBodySummary: public CHeapObj {
67 define_num_seq(satb_drain) // optional
68 define_num_seq(parallel) // parallel only
69 define_num_seq(ext_root_scan)
70 define_num_seq(mark_stack_scan)
71 define_num_seq(update_rs)
72 define_num_seq(scan_rs)
73 define_num_seq(obj_copy)
74 define_num_seq(termination) // parallel only
75 define_num_seq(parallel_other) // parallel only
76 define_num_seq(mark_closure)
77 define_num_seq(clear_ct)
78 };
80 class Summary: public PauseSummary,
81 public MainBodySummary {
82 public:
83 virtual MainBodySummary* main_body_summary() { return this; }
84 };
86 class G1CollectorPolicy: public CollectorPolicy {
87 private:
88 // either equal to the number of parallel threads, if ParallelGCThreads
89 // has been set, or 1 otherwise
90 int _parallel_gc_threads;
92 // The number of GC threads currently active.
93 uintx _no_of_gc_threads;
95 enum SomePrivateConstants {
96 NumPrevPausesForHeuristics = 10
97 };
99 G1MMUTracker* _mmu_tracker;
101 void initialize_flags();
103 void initialize_all() {
104 initialize_flags();
105 initialize_size_info();
106 initialize_perm_generation(PermGen::MarkSweepCompact);
107 }
109 CollectionSetChooser* _collectionSetChooser;
111 double _cur_collection_start_sec;
112 size_t _cur_collection_pause_used_at_start_bytes;
113 size_t _cur_collection_pause_used_regions_at_start;
114 size_t _prev_collection_pause_used_at_end_bytes;
115 double _cur_collection_par_time_ms;
116 double _cur_satb_drain_time_ms;
117 double _cur_clear_ct_time_ms;
118 double _cur_ref_proc_time_ms;
119 double _cur_ref_enq_time_ms;
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 // These exclude marking times.
131 TruncatedSeq* _recent_gc_times_ms;
133 TruncatedSeq* _concurrent_mark_remark_times_ms;
134 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
136 Summary* _summary;
138 NumberSeq* _all_pause_times_ms;
139 NumberSeq* _all_full_gc_times_ms;
140 double _stop_world_start;
141 NumberSeq* _all_stop_world_times_ms;
142 NumberSeq* _all_yield_times_ms;
144 int _aux_num;
145 NumberSeq* _all_aux_times_ms;
146 double* _cur_aux_start_times_ms;
147 double* _cur_aux_times_ms;
148 bool* _cur_aux_times_set;
150 double* _par_last_gc_worker_start_times_ms;
151 double* _par_last_ext_root_scan_times_ms;
152 double* _par_last_mark_stack_scan_times_ms;
153 double* _par_last_update_rs_times_ms;
154 double* _par_last_update_rs_processed_buffers;
155 double* _par_last_scan_rs_times_ms;
156 double* _par_last_obj_copy_times_ms;
157 double* _par_last_termination_times_ms;
158 double* _par_last_termination_attempts;
159 double* _par_last_gc_worker_end_times_ms;
160 double* _par_last_gc_worker_times_ms;
162 // Each workers 'other' time i.e. the elapsed time of the parallel
163 // phase of the pause minus the sum of the individual sub-phase
164 // times for a given worker thread.
165 double* _par_last_gc_worker_other_times_ms;
167 // indicates whether we are in full young or partially young GC mode
168 bool _full_young_gcs;
170 // if true, then it tries to dynamically adjust the length of the
171 // young list
172 bool _adaptive_young_list_length;
173 size_t _young_list_target_length;
174 size_t _young_list_fixed_length;
175 size_t _prev_eden_capacity; // used for logging
177 // The max number of regions we can extend the eden by while the GC
178 // locker is active. This should be >= _young_list_target_length;
179 size_t _young_list_max_length;
181 bool _last_young_gc_full;
183 unsigned _full_young_pause_num;
184 unsigned _partial_young_pause_num;
186 bool _during_marking;
187 bool _in_marking_window;
188 bool _in_marking_window_im;
190 SurvRateGroup* _short_lived_surv_rate_group;
191 SurvRateGroup* _survivor_surv_rate_group;
192 // add here any more surv rate groups
194 double _gc_overhead_perc;
196 double _reserve_factor;
197 size_t _reserve_regions;
199 bool during_marking() {
200 return _during_marking;
201 }
203 private:
204 enum PredictionConstants {
205 TruncatedSeqLength = 10
206 };
208 TruncatedSeq* _alloc_rate_ms_seq;
209 double _prev_collection_pause_end_ms;
211 TruncatedSeq* _pending_card_diff_seq;
212 TruncatedSeq* _rs_length_diff_seq;
213 TruncatedSeq* _cost_per_card_ms_seq;
214 TruncatedSeq* _fully_young_cards_per_entry_ratio_seq;
215 TruncatedSeq* _partially_young_cards_per_entry_ratio_seq;
216 TruncatedSeq* _cost_per_entry_ms_seq;
217 TruncatedSeq* _partially_young_cost_per_entry_ms_seq;
218 TruncatedSeq* _cost_per_byte_ms_seq;
219 TruncatedSeq* _constant_other_time_ms_seq;
220 TruncatedSeq* _young_other_cost_per_region_ms_seq;
221 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
223 TruncatedSeq* _pending_cards_seq;
224 TruncatedSeq* _rs_lengths_seq;
226 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
228 TruncatedSeq* _young_gc_eff_seq;
230 bool _using_new_ratio_calculations;
231 size_t _min_desired_young_length; // as set on the command line or default calculations
232 size_t _max_desired_young_length; // as set on the command line or default calculations
234 size_t _eden_cset_region_length;
235 size_t _survivor_cset_region_length;
236 size_t _old_cset_region_length;
238 void init_cset_region_lengths(size_t eden_cset_region_length,
239 size_t survivor_cset_region_length);
241 size_t eden_cset_region_length() { return _eden_cset_region_length; }
242 size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
243 size_t old_cset_region_length() { return _old_cset_region_length; }
245 size_t _free_regions_at_end_of_collection;
247 size_t _recorded_rs_lengths;
248 size_t _max_rs_lengths;
250 double _recorded_young_free_cset_time_ms;
251 double _recorded_non_young_free_cset_time_ms;
253 double _sigma;
254 double _expensive_region_limit_ms;
256 size_t _rs_lengths_prediction;
258 size_t _known_garbage_bytes;
259 double _known_garbage_ratio;
261 double sigma() {
262 return _sigma;
263 }
265 // A function that prevents us putting too much stock in small sample
266 // sets. Returns a number between 2.0 and 1.0, depending on the number
267 // of samples. 5 or more samples yields one; fewer scales linearly from
268 // 2.0 at 1 sample to 1.0 at 5.
269 double confidence_factor(int samples) {
270 if (samples > 4) return 1.0;
271 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
272 }
274 double get_new_neg_prediction(TruncatedSeq* seq) {
275 return seq->davg() - sigma() * seq->dsd();
276 }
278 #ifndef PRODUCT
279 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
280 #endif // PRODUCT
282 void adjust_concurrent_refinement(double update_rs_time,
283 double update_rs_processed_buffers,
284 double goal_ms);
286 uintx no_of_gc_threads() { return _no_of_gc_threads; }
287 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
289 double _pause_time_target_ms;
290 double _recorded_young_cset_choice_time_ms;
291 double _recorded_non_young_cset_choice_time_ms;
292 size_t _pending_cards;
293 size_t _max_pending_cards;
295 public:
296 // Accessors
298 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
299 hr->set_young();
300 hr->install_surv_rate_group(_short_lived_surv_rate_group);
301 hr->set_young_index_in_cset(young_index_in_cset);
302 }
304 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
305 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
306 hr->install_surv_rate_group(_survivor_surv_rate_group);
307 hr->set_young_index_in_cset(young_index_in_cset);
308 }
310 #ifndef PRODUCT
311 bool verify_young_ages();
312 #endif // PRODUCT
314 double get_new_prediction(TruncatedSeq* seq) {
315 return MAX2(seq->davg() + sigma() * seq->dsd(),
316 seq->davg() * confidence_factor(seq->num()));
317 }
319 void record_max_rs_lengths(size_t rs_lengths) {
320 _max_rs_lengths = rs_lengths;
321 }
323 size_t predict_pending_card_diff() {
324 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
325 if (prediction < 0.00001)
326 return 0;
327 else
328 return (size_t) prediction;
329 }
331 size_t predict_pending_cards() {
332 size_t max_pending_card_num = _g1->max_pending_card_num();
333 size_t diff = predict_pending_card_diff();
334 size_t prediction;
335 if (diff > max_pending_card_num)
336 prediction = max_pending_card_num;
337 else
338 prediction = max_pending_card_num - diff;
340 return prediction;
341 }
343 size_t predict_rs_length_diff() {
344 return (size_t) get_new_prediction(_rs_length_diff_seq);
345 }
347 double predict_alloc_rate_ms() {
348 return get_new_prediction(_alloc_rate_ms_seq);
349 }
351 double predict_cost_per_card_ms() {
352 return get_new_prediction(_cost_per_card_ms_seq);
353 }
355 double predict_rs_update_time_ms(size_t pending_cards) {
356 return (double) pending_cards * predict_cost_per_card_ms();
357 }
359 double predict_fully_young_cards_per_entry_ratio() {
360 return get_new_prediction(_fully_young_cards_per_entry_ratio_seq);
361 }
363 double predict_partially_young_cards_per_entry_ratio() {
364 if (_partially_young_cards_per_entry_ratio_seq->num() < 2)
365 return predict_fully_young_cards_per_entry_ratio();
366 else
367 return get_new_prediction(_partially_young_cards_per_entry_ratio_seq);
368 }
370 size_t predict_young_card_num(size_t rs_length) {
371 return (size_t) ((double) rs_length *
372 predict_fully_young_cards_per_entry_ratio());
373 }
375 size_t predict_non_young_card_num(size_t rs_length) {
376 return (size_t) ((double) rs_length *
377 predict_partially_young_cards_per_entry_ratio());
378 }
380 double predict_rs_scan_time_ms(size_t card_num) {
381 if (full_young_gcs())
382 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
383 else
384 return predict_partially_young_rs_scan_time_ms(card_num);
385 }
387 double predict_partially_young_rs_scan_time_ms(size_t card_num) {
388 if (_partially_young_cost_per_entry_ms_seq->num() < 3)
389 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
390 else
391 return (double) card_num *
392 get_new_prediction(_partially_young_cost_per_entry_ms_seq);
393 }
395 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
396 if (_cost_per_byte_ms_during_cm_seq->num() < 3)
397 return 1.1 * (double) bytes_to_copy *
398 get_new_prediction(_cost_per_byte_ms_seq);
399 else
400 return (double) bytes_to_copy *
401 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
402 }
404 double predict_object_copy_time_ms(size_t bytes_to_copy) {
405 if (_in_marking_window && !_in_marking_window_im)
406 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
407 else
408 return (double) bytes_to_copy *
409 get_new_prediction(_cost_per_byte_ms_seq);
410 }
412 double predict_constant_other_time_ms() {
413 return get_new_prediction(_constant_other_time_ms_seq);
414 }
416 double predict_young_other_time_ms(size_t young_num) {
417 return
418 (double) young_num *
419 get_new_prediction(_young_other_cost_per_region_ms_seq);
420 }
422 double predict_non_young_other_time_ms(size_t non_young_num) {
423 return
424 (double) non_young_num *
425 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
426 }
428 void check_if_region_is_too_expensive(double predicted_time_ms);
430 double predict_young_collection_elapsed_time_ms(size_t adjustment);
431 double predict_base_elapsed_time_ms(size_t pending_cards);
432 double predict_base_elapsed_time_ms(size_t pending_cards,
433 size_t scanned_cards);
434 size_t predict_bytes_to_copy(HeapRegion* hr);
435 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
437 void set_recorded_rs_lengths(size_t rs_lengths);
439 size_t cset_region_length() { return young_cset_region_length() +
440 old_cset_region_length(); }
441 size_t young_cset_region_length() { return eden_cset_region_length() +
442 survivor_cset_region_length(); }
444 void record_young_free_cset_time_ms(double time_ms) {
445 _recorded_young_free_cset_time_ms = time_ms;
446 }
448 void record_non_young_free_cset_time_ms(double time_ms) {
449 _recorded_non_young_free_cset_time_ms = time_ms;
450 }
452 double predict_young_gc_eff() {
453 return get_new_neg_prediction(_young_gc_eff_seq);
454 }
456 double predict_survivor_regions_evac_time();
458 void cset_regions_freed() {
459 bool propagate = _last_young_gc_full && !_in_marking_window;
460 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
461 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
462 // also call it on any more surv rate groups
463 }
465 void set_known_garbage_bytes(size_t known_garbage_bytes) {
466 _known_garbage_bytes = known_garbage_bytes;
467 size_t heap_bytes = _g1->capacity();
468 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
469 }
471 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
472 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
474 _known_garbage_bytes -= known_garbage_bytes;
475 size_t heap_bytes = _g1->capacity();
476 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
477 }
479 G1MMUTracker* mmu_tracker() {
480 return _mmu_tracker;
481 }
483 double max_pause_time_ms() {
484 return _mmu_tracker->max_gc_time() * 1000.0;
485 }
487 double predict_remark_time_ms() {
488 return get_new_prediction(_concurrent_mark_remark_times_ms);
489 }
491 double predict_cleanup_time_ms() {
492 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
493 }
495 // Returns an estimate of the survival rate of the region at yg-age
496 // "yg_age".
497 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
498 TruncatedSeq* seq = surv_rate_group->get_seq(age);
499 if (seq->num() == 0)
500 gclog_or_tty->print("BARF! age is %d", age);
501 guarantee( seq->num() > 0, "invariant" );
502 double pred = get_new_prediction(seq);
503 if (pred > 1.0)
504 pred = 1.0;
505 return pred;
506 }
508 double predict_yg_surv_rate(int age) {
509 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
510 }
512 double accum_yg_surv_rate_pred(int age) {
513 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
514 }
516 private:
517 void print_stats(int level, const char* str, double value);
518 void print_stats(int level, const char* str, int value);
520 void print_par_stats(int level, const char* str, double* data);
521 void print_par_sizes(int level, const char* str, double* data);
523 void check_other_times(int level,
524 NumberSeq* other_times_ms,
525 NumberSeq* calc_other_times_ms) const;
527 void print_summary (PauseSummary* stats) const;
529 void print_summary (int level, const char* str, NumberSeq* seq) const;
530 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
532 double avg_value (double* data);
533 double max_value (double* data);
534 double sum_of_values (double* data);
535 double max_sum (double* data1, double* data2);
537 double _last_pause_time_ms;
539 size_t _bytes_in_collection_set_before_gc;
540 size_t _bytes_copied_during_gc;
542 // Used to count used bytes in CS.
543 friend class CountCSClosure;
545 // Statistics kept per GC stoppage, pause or full.
546 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
548 // Add a new GC of the given duration and end time to the record.
549 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
551 // The head of the list (via "next_in_collection_set()") representing the
552 // current collection set. Set from the incrementally built collection
553 // set at the start of the pause.
554 HeapRegion* _collection_set;
556 // The number of bytes in the collection set before the pause. Set from
557 // the incrementally built collection set at the start of an evacuation
558 // pause.
559 size_t _collection_set_bytes_used_before;
561 // The associated information that is maintained while the incremental
562 // collection set is being built with young regions. Used to populate
563 // the recorded info for the evacuation pause.
565 enum CSetBuildType {
566 Active, // We are actively building the collection set
567 Inactive // We are not actively building the collection set
568 };
570 CSetBuildType _inc_cset_build_state;
572 // The head of the incrementally built collection set.
573 HeapRegion* _inc_cset_head;
575 // The tail of the incrementally built collection set.
576 HeapRegion* _inc_cset_tail;
578 // The number of bytes in the incrementally built collection set.
579 // Used to set _collection_set_bytes_used_before at the start of
580 // an evacuation pause.
581 size_t _inc_cset_bytes_used_before;
583 // Used to record the highest end of heap region in collection set
584 HeapWord* _inc_cset_max_finger;
586 // The RSet lengths recorded for regions in the collection set
587 // (updated by the periodic sampling of the regions in the
588 // young list/collection set).
589 size_t _inc_cset_recorded_rs_lengths;
591 // The predicted elapsed time it will take to collect the regions
592 // in the collection set (updated by the periodic sampling of the
593 // regions in the young list/collection set).
594 double _inc_cset_predicted_elapsed_time_ms;
596 // Stash a pointer to the g1 heap.
597 G1CollectedHeap* _g1;
599 // The ratio of gc time to elapsed time, computed over recent pauses.
600 double _recent_avg_pause_time_ratio;
602 double recent_avg_pause_time_ratio() {
603 return _recent_avg_pause_time_ratio;
604 }
606 // At the end of a pause we check the heap occupancy and we decide
607 // whether we will start a marking cycle during the next pause. If
608 // we decide that we want to do that, we will set this parameter to
609 // true. So, this parameter will stay true between the end of a
610 // pause and the beginning of a subsequent pause (not necessarily
611 // the next one, see the comments on the next field) when we decide
612 // that we will indeed start a marking cycle and do the initial-mark
613 // work.
614 volatile bool _initiate_conc_mark_if_possible;
616 // If initiate_conc_mark_if_possible() is set at the beginning of a
617 // pause, it is a suggestion that the pause should start a marking
618 // cycle by doing the initial-mark work. However, it is possible
619 // that the concurrent marking thread is still finishing up the
620 // previous marking cycle (e.g., clearing the next marking
621 // bitmap). If that is the case we cannot start a new cycle and
622 // we'll have to wait for the concurrent marking thread to finish
623 // what it is doing. In this case we will postpone the marking cycle
624 // initiation decision for the next pause. When we eventually decide
625 // to start a cycle, we will set _during_initial_mark_pause which
626 // will stay true until the end of the initial-mark pause and it's
627 // the condition that indicates that a pause is doing the
628 // initial-mark work.
629 volatile bool _during_initial_mark_pause;
631 bool _should_revert_to_full_young_gcs;
632 bool _last_full_young_gc;
634 // This set of variables tracks the collector efficiency, in order to
635 // determine whether we should initiate a new marking.
636 double _cur_mark_stop_world_time_ms;
637 double _mark_remark_start_sec;
638 double _mark_cleanup_start_sec;
639 double _mark_closure_time_ms;
641 // Update the young list target length either by setting it to the
642 // desired fixed value or by calculating it using G1's pause
643 // prediction model. If no rs_lengths parameter is passed, predict
644 // the RS lengths using the prediction model, otherwise use the
645 // given rs_lengths as the prediction.
646 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
648 // Calculate and return the minimum desired young list target
649 // length. This is the minimum desired young list length according
650 // to the user's inputs.
651 size_t calculate_young_list_desired_min_length(size_t base_min_length);
653 // Calculate and return the maximum desired young list target
654 // length. This is the maximum desired young list length according
655 // to the user's inputs.
656 size_t calculate_young_list_desired_max_length();
658 // Calculate and return the maximum young list target length that
659 // can fit into the pause time goal. The parameters are: rs_lengths
660 // represent the prediction of how large the young RSet lengths will
661 // be, base_min_length is the alreay existing number of regions in
662 // the young list, min_length and max_length are the desired min and
663 // max young list length according to the user's inputs.
664 size_t calculate_young_list_target_length(size_t rs_lengths,
665 size_t base_min_length,
666 size_t desired_min_length,
667 size_t desired_max_length);
669 // Check whether a given young length (young_length) fits into the
670 // given target pause time and whether the prediction for the amount
671 // of objects to be copied for the given length will fit into the
672 // given free space (expressed by base_free_regions). It is used by
673 // calculate_young_list_target_length().
674 bool predict_will_fit(size_t young_length, double base_time_ms,
675 size_t base_free_regions, double target_pause_time_ms);
677 // Count the number of bytes used in the CS.
678 void count_CS_bytes_used();
680 void update_young_list_size_using_newratio(size_t number_of_heap_regions);
682 public:
684 G1CollectorPolicy();
686 virtual G1CollectorPolicy* as_g1_policy() { return this; }
688 virtual CollectorPolicy::Name kind() {
689 return CollectorPolicy::G1CollectorPolicyKind;
690 }
692 // Check the current value of the young list RSet lengths and
693 // compare it against the last prediction. If the current value is
694 // higher, recalculate the young list target length prediction.
695 void revise_young_list_target_length_if_necessary();
697 size_t bytes_in_collection_set() {
698 return _bytes_in_collection_set_before_gc;
699 }
701 unsigned calc_gc_alloc_time_stamp() {
702 return _all_pause_times_ms->num() + 1;
703 }
705 // This should be called after the heap is resized.
706 void record_new_heap_size(size_t new_number_of_regions);
708 public:
710 void init();
712 // Create jstat counters for the policy.
713 virtual void initialize_gc_policy_counters();
715 virtual HeapWord* mem_allocate_work(size_t size,
716 bool is_tlab,
717 bool* gc_overhead_limit_was_exceeded);
719 // This method controls how a collector handles one or more
720 // of its generations being fully allocated.
721 virtual HeapWord* satisfy_failed_allocation(size_t size,
722 bool is_tlab);
724 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
726 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
728 // Update the heuristic info to record a collection pause of the given
729 // start time, where the given number of bytes were used at the start.
730 // This may involve changing the desired size of a collection set.
732 void record_stop_world_start();
734 void record_collection_pause_start(double start_time_sec, size_t start_used);
736 // Must currently be called while the world is stopped.
737 void record_concurrent_mark_init_end(double
738 mark_init_elapsed_time_ms);
740 void record_mark_closure_time(double mark_closure_time_ms) {
741 _mark_closure_time_ms = mark_closure_time_ms;
742 }
744 void record_concurrent_mark_remark_start();
745 void record_concurrent_mark_remark_end();
747 void record_concurrent_mark_cleanup_start();
748 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
749 void record_concurrent_mark_cleanup_completed();
751 void record_concurrent_pause();
752 void record_concurrent_pause_end();
754 void record_collection_pause_end(int no_of_gc_threads);
755 void print_heap_transition();
757 // Record the fact that a full collection occurred.
758 void record_full_collection_start();
759 void record_full_collection_end();
761 void record_gc_worker_start_time(int worker_i, double ms) {
762 _par_last_gc_worker_start_times_ms[worker_i] = ms;
763 }
765 void record_ext_root_scan_time(int worker_i, double ms) {
766 _par_last_ext_root_scan_times_ms[worker_i] = ms;
767 }
769 void record_mark_stack_scan_time(int worker_i, double ms) {
770 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
771 }
773 void record_satb_drain_time(double ms) {
774 assert(_g1->mark_in_progress(), "shouldn't be here otherwise");
775 _cur_satb_drain_time_ms = ms;
776 }
778 void record_update_rs_time(int thread, double ms) {
779 _par_last_update_rs_times_ms[thread] = ms;
780 }
782 void record_update_rs_processed_buffers (int thread,
783 double processed_buffers) {
784 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
785 }
787 void record_scan_rs_time(int thread, double ms) {
788 _par_last_scan_rs_times_ms[thread] = ms;
789 }
791 void reset_obj_copy_time(int thread) {
792 _par_last_obj_copy_times_ms[thread] = 0.0;
793 }
795 void reset_obj_copy_time() {
796 reset_obj_copy_time(0);
797 }
799 void record_obj_copy_time(int thread, double ms) {
800 _par_last_obj_copy_times_ms[thread] += ms;
801 }
803 void record_termination(int thread, double ms, size_t attempts) {
804 _par_last_termination_times_ms[thread] = ms;
805 _par_last_termination_attempts[thread] = (double) attempts;
806 }
808 void record_gc_worker_end_time(int worker_i, double ms) {
809 _par_last_gc_worker_end_times_ms[worker_i] = ms;
810 }
812 void record_pause_time_ms(double ms) {
813 _last_pause_time_ms = ms;
814 }
816 void record_clear_ct_time(double ms) {
817 _cur_clear_ct_time_ms = ms;
818 }
820 void record_par_time(double ms) {
821 _cur_collection_par_time_ms = ms;
822 }
824 void record_aux_start_time(int i) {
825 guarantee(i < _aux_num, "should be within range");
826 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
827 }
829 void record_aux_end_time(int i) {
830 guarantee(i < _aux_num, "should be within range");
831 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
832 _cur_aux_times_set[i] = true;
833 _cur_aux_times_ms[i] += ms;
834 }
836 void record_ref_proc_time(double ms) {
837 _cur_ref_proc_time_ms = ms;
838 }
840 void record_ref_enq_time(double ms) {
841 _cur_ref_enq_time_ms = ms;
842 }
844 #ifndef PRODUCT
845 void record_cc_clear_time(double ms) {
846 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
847 _min_clear_cc_time_ms = ms;
848 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
849 _max_clear_cc_time_ms = ms;
850 _cur_clear_cc_time_ms = ms;
851 _cum_clear_cc_time_ms += ms;
852 _num_cc_clears++;
853 }
854 #endif
856 // Record how much space we copied during a GC. This is typically
857 // called when a GC alloc region is being retired.
858 void record_bytes_copied_during_gc(size_t bytes) {
859 _bytes_copied_during_gc += bytes;
860 }
862 // The amount of space we copied during a GC.
863 size_t bytes_copied_during_gc() {
864 return _bytes_copied_during_gc;
865 }
867 // Choose a new collection set. Marks the chosen regions as being
868 // "in_collection_set", and links them together. The head and number of
869 // the collection set are available via access methods.
870 void choose_collection_set(double target_pause_time_ms);
872 // The head of the list (via "next_in_collection_set()") representing the
873 // current collection set.
874 HeapRegion* collection_set() { return _collection_set; }
876 void clear_collection_set() { _collection_set = NULL; }
878 // Add old region "hr" to the CSet.
879 void add_old_region_to_cset(HeapRegion* hr);
881 // Incremental CSet Support
883 // The head of the incrementally built collection set.
884 HeapRegion* inc_cset_head() { return _inc_cset_head; }
886 // The tail of the incrementally built collection set.
887 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
889 // Initialize incremental collection set info.
890 void start_incremental_cset_building();
892 void clear_incremental_cset() {
893 _inc_cset_head = NULL;
894 _inc_cset_tail = NULL;
895 }
897 // Stop adding regions to the incremental collection set
898 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
900 // Add/remove information about hr to the aggregated information
901 // for the incrementally built collection set.
902 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
903 void remove_from_incremental_cset_info(HeapRegion* hr);
905 // Update information about hr in the aggregated information for
906 // the incrementally built collection set.
907 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
909 private:
910 // Update the incremental cset information when adding a region
911 // (should not be called directly).
912 void add_region_to_incremental_cset_common(HeapRegion* hr);
914 public:
915 // Add hr to the LHS of the incremental collection set.
916 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
918 // Add hr to the RHS of the incremental collection set.
919 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
921 #ifndef PRODUCT
922 void print_collection_set(HeapRegion* list_head, outputStream* st);
923 #endif // !PRODUCT
925 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
926 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
927 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
929 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
930 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
931 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
933 // This sets the initiate_conc_mark_if_possible() flag to start a
934 // new cycle, as long as we are not already in one. It's best if it
935 // is called during a safepoint when the test whether a cycle is in
936 // progress or not is stable.
937 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
939 // This is called at the very beginning of an evacuation pause (it
940 // has to be the first thing that the pause does). If
941 // initiate_conc_mark_if_possible() is true, and the concurrent
942 // marking thread has completed its work during the previous cycle,
943 // it will set during_initial_mark_pause() to so that the pause does
944 // the initial-mark work and start a marking cycle.
945 void decide_on_conc_mark_initiation();
947 // If an expansion would be appropriate, because recent GC overhead had
948 // exceeded the desired limit, return an amount to expand by.
949 size_t expansion_amount();
951 #ifndef PRODUCT
952 // Check any appropriate marked bytes info, asserting false if
953 // something's wrong, else returning "true".
954 bool assertMarkedBytesDataOK();
955 #endif
957 // Print tracing information.
958 void print_tracing_info() const;
960 // Print stats on young survival ratio
961 void print_yg_surv_rate_info() const;
963 void finished_recalculating_age_indexes(bool is_survivors) {
964 if (is_survivors) {
965 _survivor_surv_rate_group->finished_recalculating_age_indexes();
966 } else {
967 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
968 }
969 // do that for any other surv rate groups
970 }
972 bool is_young_list_full() {
973 size_t young_list_length = _g1->young_list()->length();
974 size_t young_list_target_length = _young_list_target_length;
975 return young_list_length >= young_list_target_length;
976 }
978 bool can_expand_young_list() {
979 size_t young_list_length = _g1->young_list()->length();
980 size_t young_list_max_length = _young_list_max_length;
981 return young_list_length < young_list_max_length;
982 }
984 size_t young_list_max_length() {
985 return _young_list_max_length;
986 }
988 bool full_young_gcs() {
989 return _full_young_gcs;
990 }
991 void set_full_young_gcs(bool full_young_gcs) {
992 _full_young_gcs = full_young_gcs;
993 }
995 bool adaptive_young_list_length() {
996 return _adaptive_young_list_length;
997 }
998 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
999 _adaptive_young_list_length = adaptive_young_list_length;
1000 }
1002 inline double get_gc_eff_factor() {
1003 double ratio = _known_garbage_ratio;
1005 double square = ratio * ratio;
1006 // square = square * square;
1007 double ret = square * 9.0 + 1.0;
1008 #if 0
1009 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1010 #endif // 0
1011 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1012 return ret;
1013 }
1015 private:
1016 //
1017 // Survivor regions policy.
1018 //
1020 // Current tenuring threshold, set to 0 if the collector reaches the
1021 // maximum amount of suvivors regions.
1022 int _tenuring_threshold;
1024 // The limit on the number of regions allocated for survivors.
1025 size_t _max_survivor_regions;
1027 // For reporting purposes.
1028 size_t _eden_bytes_before_gc;
1029 size_t _survivor_bytes_before_gc;
1030 size_t _capacity_before_gc;
1032 // The amount of survor regions after a collection.
1033 size_t _recorded_survivor_regions;
1034 // List of survivor regions.
1035 HeapRegion* _recorded_survivor_head;
1036 HeapRegion* _recorded_survivor_tail;
1038 ageTable _survivors_age_table;
1040 public:
1042 inline GCAllocPurpose
1043 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1044 if (age < _tenuring_threshold && src_region->is_young()) {
1045 return GCAllocForSurvived;
1046 } else {
1047 return GCAllocForTenured;
1048 }
1049 }
1051 inline bool track_object_age(GCAllocPurpose purpose) {
1052 return purpose == GCAllocForSurvived;
1053 }
1055 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1057 size_t max_regions(int purpose);
1059 // The limit on regions for a particular purpose is reached.
1060 void note_alloc_region_limit_reached(int purpose) {
1061 if (purpose == GCAllocForSurvived) {
1062 _tenuring_threshold = 0;
1063 }
1064 }
1066 void note_start_adding_survivor_regions() {
1067 _survivor_surv_rate_group->start_adding_regions();
1068 }
1070 void note_stop_adding_survivor_regions() {
1071 _survivor_surv_rate_group->stop_adding_regions();
1072 }
1074 void record_survivor_regions(size_t regions,
1075 HeapRegion* head,
1076 HeapRegion* tail) {
1077 _recorded_survivor_regions = regions;
1078 _recorded_survivor_head = head;
1079 _recorded_survivor_tail = tail;
1080 }
1082 size_t recorded_survivor_regions() {
1083 return _recorded_survivor_regions;
1084 }
1086 void record_thread_age_table(ageTable* age_table)
1087 {
1088 _survivors_age_table.merge_par(age_table);
1089 }
1091 void update_max_gc_locker_expansion();
1093 // Calculates survivor space parameters.
1094 void update_survivors_policy();
1096 };
1098 // This should move to some place more general...
1100 // If we have "n" measurements, and we've kept track of their "sum" and the
1101 // "sum_of_squares" of the measurements, this returns the variance of the
1102 // sequence.
1103 inline double variance(int n, double sum_of_squares, double sum) {
1104 double n_d = (double)n;
1105 double avg = sum/n_d;
1106 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1107 }
1109 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP