Mon, 16 Jul 2012 13:00:26 -0700
Merge
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
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.
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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;
39 class G1GCPhaseTimes;
41 // TraceGen0Time collects data on _both_ young and mixed evacuation pauses
42 // (the latter may contain non-young regions - i.e. regions that are
43 // technically in Gen1) while TraceGen1Time collects data about full GCs.
44 class TraceGen0TimeData : public CHeapObj<mtGC> {
45 private:
46 unsigned _young_pause_num;
47 unsigned _mixed_pause_num;
49 NumberSeq _all_stop_world_times_ms;
50 NumberSeq _all_yield_times_ms;
52 NumberSeq _total;
53 NumberSeq _other;
54 NumberSeq _root_region_scan_wait;
55 NumberSeq _parallel;
56 NumberSeq _ext_root_scan;
57 NumberSeq _satb_filtering;
58 NumberSeq _update_rs;
59 NumberSeq _scan_rs;
60 NumberSeq _obj_copy;
61 NumberSeq _termination;
62 NumberSeq _parallel_other;
63 NumberSeq _clear_ct;
65 void print_summary(const char* str, const NumberSeq* seq) const;
66 void print_summary_sd(const char* str, const NumberSeq* seq) const;
68 public:
69 TraceGen0TimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
70 void record_start_collection(double time_to_stop_the_world_ms);
71 void record_yield_time(double yield_time_ms);
72 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
73 void increment_young_collection_count();
74 void increment_mixed_collection_count();
75 void print() const;
76 };
78 class TraceGen1TimeData : public CHeapObj<mtGC> {
79 private:
80 NumberSeq _all_full_gc_times;
82 public:
83 void record_full_collection(double full_gc_time_ms);
84 void print() const;
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<mtGC> {
124 private:
125 enum SizerKind {
126 SizerDefaults,
127 SizerNewSizeOnly,
128 SizerMaxNewSizeOnly,
129 SizerMaxAndNewSize,
130 SizerNewRatio
131 };
132 SizerKind _sizer_kind;
133 uint _min_desired_young_length;
134 uint _max_desired_young_length;
135 bool _adaptive_size;
136 uint calculate_default_min_length(uint new_number_of_heap_regions);
137 uint calculate_default_max_length(uint new_number_of_heap_regions);
139 public:
140 G1YoungGenSizer();
141 void heap_size_changed(uint new_number_of_heap_regions);
142 uint min_desired_young_length() {
143 return _min_desired_young_length;
144 }
145 uint 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 _full_collection_start_sec;
179 size_t _cur_collection_pause_used_at_start_bytes;
180 uint _cur_collection_pause_used_regions_at_start;
182 // These exclude marking times.
183 TruncatedSeq* _recent_gc_times_ms;
185 TruncatedSeq* _concurrent_mark_remark_times_ms;
186 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
188 TraceGen0TimeData _trace_gen0_time_data;
189 TraceGen1TimeData _trace_gen1_time_data;
191 double _stop_world_start;
193 // indicates whether we are in young or mixed GC mode
194 bool _gcs_are_young;
196 uint _young_list_target_length;
197 uint _young_list_fixed_length;
198 size_t _prev_eden_capacity; // used for logging
200 // The max number of regions we can extend the eden by while the GC
201 // locker is active. This should be >= _young_list_target_length;
202 uint _young_list_max_length;
204 bool _last_gc_was_young;
206 bool _during_marking;
207 bool _in_marking_window;
208 bool _in_marking_window_im;
210 SurvRateGroup* _short_lived_surv_rate_group;
211 SurvRateGroup* _survivor_surv_rate_group;
212 // add here any more surv rate groups
214 double _gc_overhead_perc;
216 double _reserve_factor;
217 uint _reserve_regions;
219 bool during_marking() {
220 return _during_marking;
221 }
223 private:
224 enum PredictionConstants {
225 TruncatedSeqLength = 10
226 };
228 TruncatedSeq* _alloc_rate_ms_seq;
229 double _prev_collection_pause_end_ms;
231 TruncatedSeq* _pending_card_diff_seq;
232 TruncatedSeq* _rs_length_diff_seq;
233 TruncatedSeq* _cost_per_card_ms_seq;
234 TruncatedSeq* _young_cards_per_entry_ratio_seq;
235 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
236 TruncatedSeq* _cost_per_entry_ms_seq;
237 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
238 TruncatedSeq* _cost_per_byte_ms_seq;
239 TruncatedSeq* _constant_other_time_ms_seq;
240 TruncatedSeq* _young_other_cost_per_region_ms_seq;
241 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
243 TruncatedSeq* _pending_cards_seq;
244 TruncatedSeq* _rs_lengths_seq;
246 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
248 G1YoungGenSizer* _young_gen_sizer;
250 uint _eden_cset_region_length;
251 uint _survivor_cset_region_length;
252 uint _old_cset_region_length;
254 void init_cset_region_lengths(uint eden_cset_region_length,
255 uint survivor_cset_region_length);
257 uint eden_cset_region_length() { return _eden_cset_region_length; }
258 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
259 uint old_cset_region_length() { return _old_cset_region_length; }
261 uint _free_regions_at_end_of_collection;
263 size_t _recorded_rs_lengths;
264 size_t _max_rs_lengths;
265 double _sigma;
267 size_t _rs_lengths_prediction;
269 double sigma() { return _sigma; }
271 // A function that prevents us putting too much stock in small sample
272 // sets. Returns a number between 2.0 and 1.0, depending on the number
273 // of samples. 5 or more samples yields one; fewer scales linearly from
274 // 2.0 at 1 sample to 1.0 at 5.
275 double confidence_factor(int samples) {
276 if (samples > 4) return 1.0;
277 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
278 }
280 double get_new_neg_prediction(TruncatedSeq* seq) {
281 return seq->davg() - sigma() * seq->dsd();
282 }
284 #ifndef PRODUCT
285 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
286 #endif // PRODUCT
288 void adjust_concurrent_refinement(double update_rs_time,
289 double update_rs_processed_buffers,
290 double goal_ms);
292 uintx no_of_gc_threads() { return _no_of_gc_threads; }
293 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
295 double _pause_time_target_ms;
297 size_t _pending_cards;
298 size_t _max_pending_cards;
300 public:
301 // Accessors
303 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
304 hr->set_young();
305 hr->install_surv_rate_group(_short_lived_surv_rate_group);
306 hr->set_young_index_in_cset(young_index_in_cset);
307 }
309 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
310 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
311 hr->install_surv_rate_group(_survivor_surv_rate_group);
312 hr->set_young_index_in_cset(young_index_in_cset);
313 }
315 #ifndef PRODUCT
316 bool verify_young_ages();
317 #endif // PRODUCT
319 double get_new_prediction(TruncatedSeq* seq) {
320 return MAX2(seq->davg() + sigma() * seq->dsd(),
321 seq->davg() * confidence_factor(seq->num()));
322 }
324 void record_max_rs_lengths(size_t rs_lengths) {
325 _max_rs_lengths = rs_lengths;
326 }
328 size_t predict_pending_card_diff() {
329 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
330 if (prediction < 0.00001) {
331 return 0;
332 } else {
333 return (size_t) prediction;
334 }
335 }
337 size_t predict_pending_cards() {
338 size_t max_pending_card_num = _g1->max_pending_card_num();
339 size_t diff = predict_pending_card_diff();
340 size_t prediction;
341 if (diff > max_pending_card_num) {
342 prediction = max_pending_card_num;
343 } else {
344 prediction = max_pending_card_num - diff;
345 }
347 return prediction;
348 }
350 size_t predict_rs_length_diff() {
351 return (size_t) get_new_prediction(_rs_length_diff_seq);
352 }
354 double predict_alloc_rate_ms() {
355 return get_new_prediction(_alloc_rate_ms_seq);
356 }
358 double predict_cost_per_card_ms() {
359 return get_new_prediction(_cost_per_card_ms_seq);
360 }
362 double predict_rs_update_time_ms(size_t pending_cards) {
363 return (double) pending_cards * predict_cost_per_card_ms();
364 }
366 double predict_young_cards_per_entry_ratio() {
367 return get_new_prediction(_young_cards_per_entry_ratio_seq);
368 }
370 double predict_mixed_cards_per_entry_ratio() {
371 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
372 return predict_young_cards_per_entry_ratio();
373 } else {
374 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
375 }
376 }
378 size_t predict_young_card_num(size_t rs_length) {
379 return (size_t) ((double) rs_length *
380 predict_young_cards_per_entry_ratio());
381 }
383 size_t predict_non_young_card_num(size_t rs_length) {
384 return (size_t) ((double) rs_length *
385 predict_mixed_cards_per_entry_ratio());
386 }
388 double predict_rs_scan_time_ms(size_t card_num) {
389 if (gcs_are_young()) {
390 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
391 } else {
392 return predict_mixed_rs_scan_time_ms(card_num);
393 }
394 }
396 double predict_mixed_rs_scan_time_ms(size_t card_num) {
397 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
398 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
399 } else {
400 return (double) (card_num *
401 get_new_prediction(_mixed_cost_per_entry_ms_seq));
402 }
403 }
405 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
406 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
407 return (1.1 * (double) bytes_to_copy) *
408 get_new_prediction(_cost_per_byte_ms_seq);
409 } else {
410 return (double) bytes_to_copy *
411 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
412 }
413 }
415 double predict_object_copy_time_ms(size_t bytes_to_copy) {
416 if (_in_marking_window && !_in_marking_window_im) {
417 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
418 } else {
419 return (double) bytes_to_copy *
420 get_new_prediction(_cost_per_byte_ms_seq);
421 }
422 }
424 double predict_constant_other_time_ms() {
425 return get_new_prediction(_constant_other_time_ms_seq);
426 }
428 double predict_young_other_time_ms(size_t young_num) {
429 return (double) young_num *
430 get_new_prediction(_young_other_cost_per_region_ms_seq);
431 }
433 double predict_non_young_other_time_ms(size_t non_young_num) {
434 return (double) non_young_num *
435 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
436 }
438 double predict_base_elapsed_time_ms(size_t pending_cards);
439 double predict_base_elapsed_time_ms(size_t pending_cards,
440 size_t scanned_cards);
441 size_t predict_bytes_to_copy(HeapRegion* hr);
442 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
444 void set_recorded_rs_lengths(size_t rs_lengths);
446 uint cset_region_length() { return young_cset_region_length() +
447 old_cset_region_length(); }
448 uint young_cset_region_length() { return eden_cset_region_length() +
449 survivor_cset_region_length(); }
451 double predict_survivor_regions_evac_time();
453 void cset_regions_freed() {
454 bool propagate = _last_gc_was_young && !_in_marking_window;
455 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
456 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
457 // also call it on any more surv rate groups
458 }
460 G1MMUTracker* mmu_tracker() {
461 return _mmu_tracker;
462 }
464 double max_pause_time_ms() {
465 return _mmu_tracker->max_gc_time() * 1000.0;
466 }
468 double predict_remark_time_ms() {
469 return get_new_prediction(_concurrent_mark_remark_times_ms);
470 }
472 double predict_cleanup_time_ms() {
473 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
474 }
476 // Returns an estimate of the survival rate of the region at yg-age
477 // "yg_age".
478 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
479 TruncatedSeq* seq = surv_rate_group->get_seq(age);
480 if (seq->num() == 0)
481 gclog_or_tty->print("BARF! age is %d", age);
482 guarantee( seq->num() > 0, "invariant" );
483 double pred = get_new_prediction(seq);
484 if (pred > 1.0)
485 pred = 1.0;
486 return pred;
487 }
489 double predict_yg_surv_rate(int age) {
490 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
491 }
493 double accum_yg_surv_rate_pred(int age) {
494 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
495 }
497 private:
498 size_t _bytes_in_collection_set_before_gc;
499 size_t _bytes_copied_during_gc;
501 // Used to count used bytes in CS.
502 friend class CountCSClosure;
504 // Statistics kept per GC stoppage, pause or full.
505 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
507 // Add a new GC of the given duration and end time to the record.
508 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
510 // The head of the list (via "next_in_collection_set()") representing the
511 // current collection set. Set from the incrementally built collection
512 // set at the start of the pause.
513 HeapRegion* _collection_set;
515 // The number of bytes in the collection set before the pause. Set from
516 // the incrementally built collection set at the start of an evacuation
517 // pause.
518 size_t _collection_set_bytes_used_before;
520 // The associated information that is maintained while the incremental
521 // collection set is being built with young regions. Used to populate
522 // the recorded info for the evacuation pause.
524 enum CSetBuildType {
525 Active, // We are actively building the collection set
526 Inactive // We are not actively building the collection set
527 };
529 CSetBuildType _inc_cset_build_state;
531 // The head of the incrementally built collection set.
532 HeapRegion* _inc_cset_head;
534 // The tail of the incrementally built collection set.
535 HeapRegion* _inc_cset_tail;
537 // The number of bytes in the incrementally built collection set.
538 // Used to set _collection_set_bytes_used_before at the start of
539 // an evacuation pause.
540 size_t _inc_cset_bytes_used_before;
542 // Used to record the highest end of heap region in collection set
543 HeapWord* _inc_cset_max_finger;
545 // The RSet lengths recorded for regions in the CSet. It is updated
546 // by the thread that adds a new region to the CSet. We assume that
547 // only one thread can be allocating a new CSet region (currently,
548 // it does so after taking the Heap_lock) hence no need to
549 // synchronize updates to this field.
550 size_t _inc_cset_recorded_rs_lengths;
552 // A concurrent refinement thread periodcially samples the young
553 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
554 // the RSets grow. Instead of having to syncronize updates to that
555 // field we accumulate them in this field and add it to
556 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
557 ssize_t _inc_cset_recorded_rs_lengths_diffs;
559 // The predicted elapsed time it will take to collect the regions in
560 // the CSet. This is updated by the thread that adds a new region to
561 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
562 // MT-safety assumptions.
563 double _inc_cset_predicted_elapsed_time_ms;
565 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
566 double _inc_cset_predicted_elapsed_time_ms_diffs;
568 // Stash a pointer to the g1 heap.
569 G1CollectedHeap* _g1;
571 G1GCPhaseTimes* _phase_times;
573 // The ratio of gc time to elapsed time, computed over recent pauses.
574 double _recent_avg_pause_time_ratio;
576 double recent_avg_pause_time_ratio() {
577 return _recent_avg_pause_time_ratio;
578 }
580 // At the end of a pause we check the heap occupancy and we decide
581 // whether we will start a marking cycle during the next pause. If
582 // we decide that we want to do that, we will set this parameter to
583 // true. So, this parameter will stay true between the end of a
584 // pause and the beginning of a subsequent pause (not necessarily
585 // the next one, see the comments on the next field) when we decide
586 // that we will indeed start a marking cycle and do the initial-mark
587 // work.
588 volatile bool _initiate_conc_mark_if_possible;
590 // If initiate_conc_mark_if_possible() is set at the beginning of a
591 // pause, it is a suggestion that the pause should start a marking
592 // cycle by doing the initial-mark work. However, it is possible
593 // that the concurrent marking thread is still finishing up the
594 // previous marking cycle (e.g., clearing the next marking
595 // bitmap). If that is the case we cannot start a new cycle and
596 // we'll have to wait for the concurrent marking thread to finish
597 // what it is doing. In this case we will postpone the marking cycle
598 // initiation decision for the next pause. When we eventually decide
599 // to start a cycle, we will set _during_initial_mark_pause which
600 // will stay true until the end of the initial-mark pause and it's
601 // the condition that indicates that a pause is doing the
602 // initial-mark work.
603 volatile bool _during_initial_mark_pause;
605 bool _last_young_gc;
607 // This set of variables tracks the collector efficiency, in order to
608 // determine whether we should initiate a new marking.
609 double _cur_mark_stop_world_time_ms;
610 double _mark_remark_start_sec;
611 double _mark_cleanup_start_sec;
613 // Update the young list target length either by setting it to the
614 // desired fixed value or by calculating it using G1's pause
615 // prediction model. If no rs_lengths parameter is passed, predict
616 // the RS lengths using the prediction model, otherwise use the
617 // given rs_lengths as the prediction.
618 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
620 // Calculate and return the minimum desired young list target
621 // length. This is the minimum desired young list length according
622 // to the user's inputs.
623 uint calculate_young_list_desired_min_length(uint base_min_length);
625 // Calculate and return the maximum desired young list target
626 // length. This is the maximum desired young list length according
627 // to the user's inputs.
628 uint calculate_young_list_desired_max_length();
630 // Calculate and return the maximum young list target length that
631 // can fit into the pause time goal. The parameters are: rs_lengths
632 // represent the prediction of how large the young RSet lengths will
633 // be, base_min_length is the alreay existing number of regions in
634 // the young list, min_length and max_length are the desired min and
635 // max young list length according to the user's inputs.
636 uint calculate_young_list_target_length(size_t rs_lengths,
637 uint base_min_length,
638 uint desired_min_length,
639 uint desired_max_length);
641 // Check whether a given young length (young_length) fits into the
642 // given target pause time and whether the prediction for the amount
643 // of objects to be copied for the given length will fit into the
644 // given free space (expressed by base_free_regions). It is used by
645 // calculate_young_list_target_length().
646 bool predict_will_fit(uint young_length, double base_time_ms,
647 uint base_free_regions, double target_pause_time_ms);
649 // Count the number of bytes used in the CS.
650 void count_CS_bytes_used();
652 public:
654 G1CollectorPolicy();
656 virtual G1CollectorPolicy* as_g1_policy() { return this; }
658 virtual CollectorPolicy::Name kind() {
659 return CollectorPolicy::G1CollectorPolicyKind;
660 }
662 G1GCPhaseTimes* phase_times() const { return _phase_times; }
664 // Check the current value of the young list RSet lengths and
665 // compare it against the last prediction. If the current value is
666 // higher, recalculate the young list target length prediction.
667 void revise_young_list_target_length_if_necessary();
669 size_t bytes_in_collection_set() {
670 return _bytes_in_collection_set_before_gc;
671 }
673 // This should be called after the heap is resized.
674 void record_new_heap_size(uint new_number_of_regions);
676 void init();
678 // Create jstat counters for the policy.
679 virtual void initialize_gc_policy_counters();
681 virtual HeapWord* mem_allocate_work(size_t size,
682 bool is_tlab,
683 bool* gc_overhead_limit_was_exceeded);
685 // This method controls how a collector handles one or more
686 // of its generations being fully allocated.
687 virtual HeapWord* satisfy_failed_allocation(size_t size,
688 bool is_tlab);
690 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
692 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
694 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
696 // Update the heuristic info to record a collection pause of the given
697 // start time, where the given number of bytes were used at the start.
698 // This may involve changing the desired size of a collection set.
700 void record_stop_world_start();
702 void record_collection_pause_start(double start_time_sec, size_t start_used);
704 // Must currently be called while the world is stopped.
705 void record_concurrent_mark_init_end(double
706 mark_init_elapsed_time_ms);
708 void record_concurrent_mark_remark_start();
709 void record_concurrent_mark_remark_end();
711 void record_concurrent_mark_cleanup_start();
712 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
713 void record_concurrent_mark_cleanup_completed();
715 void record_concurrent_pause();
717 void record_collection_pause_end(double pause_time);
718 void print_heap_transition();
720 // Record the fact that a full collection occurred.
721 void record_full_collection_start();
722 void record_full_collection_end();
724 // Record how much space we copied during a GC. This is typically
725 // called when a GC alloc region is being retired.
726 void record_bytes_copied_during_gc(size_t bytes) {
727 _bytes_copied_during_gc += bytes;
728 }
730 // The amount of space we copied during a GC.
731 size_t bytes_copied_during_gc() {
732 return _bytes_copied_during_gc;
733 }
735 // Determine whether there are candidate regions so that the
736 // next GC should be mixed. The two action strings are used
737 // in the ergo output when the method returns true or false.
738 bool next_gc_should_be_mixed(const char* true_action_str,
739 const char* false_action_str);
741 // Choose a new collection set. Marks the chosen regions as being
742 // "in_collection_set", and links them together. The head and number of
743 // the collection set are available via access methods.
744 void finalize_cset(double target_pause_time_ms);
746 // The head of the list (via "next_in_collection_set()") representing the
747 // current collection set.
748 HeapRegion* collection_set() { return _collection_set; }
750 void clear_collection_set() { _collection_set = NULL; }
752 // Add old region "hr" to the CSet.
753 void add_old_region_to_cset(HeapRegion* hr);
755 // Incremental CSet Support
757 // The head of the incrementally built collection set.
758 HeapRegion* inc_cset_head() { return _inc_cset_head; }
760 // The tail of the incrementally built collection set.
761 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
763 // Initialize incremental collection set info.
764 void start_incremental_cset_building();
766 // Perform any final calculations on the incremental CSet fields
767 // before we can use them.
768 void finalize_incremental_cset_building();
770 void clear_incremental_cset() {
771 _inc_cset_head = NULL;
772 _inc_cset_tail = NULL;
773 }
775 // Stop adding regions to the incremental collection set
776 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
778 // Add information about hr to the aggregated information for the
779 // incrementally built collection set.
780 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
782 // Update information about hr in the aggregated information for
783 // the incrementally built collection set.
784 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
786 private:
787 // Update the incremental cset information when adding a region
788 // (should not be called directly).
789 void add_region_to_incremental_cset_common(HeapRegion* hr);
791 public:
792 // Add hr to the LHS of the incremental collection set.
793 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
795 // Add hr to the RHS of the incremental collection set.
796 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
798 #ifndef PRODUCT
799 void print_collection_set(HeapRegion* list_head, outputStream* st);
800 #endif // !PRODUCT
802 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
803 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
804 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
806 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
807 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
808 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
810 // This sets the initiate_conc_mark_if_possible() flag to start a
811 // new cycle, as long as we are not already in one. It's best if it
812 // is called during a safepoint when the test whether a cycle is in
813 // progress or not is stable.
814 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
816 // This is called at the very beginning of an evacuation pause (it
817 // has to be the first thing that the pause does). If
818 // initiate_conc_mark_if_possible() is true, and the concurrent
819 // marking thread has completed its work during the previous cycle,
820 // it will set during_initial_mark_pause() to so that the pause does
821 // the initial-mark work and start a marking cycle.
822 void decide_on_conc_mark_initiation();
824 // If an expansion would be appropriate, because recent GC overhead had
825 // exceeded the desired limit, return an amount to expand by.
826 size_t expansion_amount();
828 // Print tracing information.
829 void print_tracing_info() const;
831 // Print stats on young survival ratio
832 void print_yg_surv_rate_info() const;
834 void finished_recalculating_age_indexes(bool is_survivors) {
835 if (is_survivors) {
836 _survivor_surv_rate_group->finished_recalculating_age_indexes();
837 } else {
838 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
839 }
840 // do that for any other surv rate groups
841 }
843 bool is_young_list_full() {
844 uint young_list_length = _g1->young_list()->length();
845 uint young_list_target_length = _young_list_target_length;
846 return young_list_length >= young_list_target_length;
847 }
849 bool can_expand_young_list() {
850 uint young_list_length = _g1->young_list()->length();
851 uint young_list_max_length = _young_list_max_length;
852 return young_list_length < young_list_max_length;
853 }
855 uint young_list_max_length() {
856 return _young_list_max_length;
857 }
859 bool gcs_are_young() {
860 return _gcs_are_young;
861 }
862 void set_gcs_are_young(bool gcs_are_young) {
863 _gcs_are_young = gcs_are_young;
864 }
866 bool adaptive_young_list_length() {
867 return _young_gen_sizer->adaptive_young_list_length();
868 }
870 private:
871 //
872 // Survivor regions policy.
873 //
875 // Current tenuring threshold, set to 0 if the collector reaches the
876 // maximum amount of suvivors regions.
877 int _tenuring_threshold;
879 // The limit on the number of regions allocated for survivors.
880 uint _max_survivor_regions;
882 // For reporting purposes.
883 size_t _eden_bytes_before_gc;
884 size_t _survivor_bytes_before_gc;
885 size_t _capacity_before_gc;
887 // The amount of survor regions after a collection.
888 uint _recorded_survivor_regions;
889 // List of survivor regions.
890 HeapRegion* _recorded_survivor_head;
891 HeapRegion* _recorded_survivor_tail;
893 ageTable _survivors_age_table;
895 public:
897 inline GCAllocPurpose
898 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
899 if (age < _tenuring_threshold && src_region->is_young()) {
900 return GCAllocForSurvived;
901 } else {
902 return GCAllocForTenured;
903 }
904 }
906 inline bool track_object_age(GCAllocPurpose purpose) {
907 return purpose == GCAllocForSurvived;
908 }
910 static const uint REGIONS_UNLIMITED = (uint) -1;
912 uint max_regions(int purpose);
914 // The limit on regions for a particular purpose is reached.
915 void note_alloc_region_limit_reached(int purpose) {
916 if (purpose == GCAllocForSurvived) {
917 _tenuring_threshold = 0;
918 }
919 }
921 void note_start_adding_survivor_regions() {
922 _survivor_surv_rate_group->start_adding_regions();
923 }
925 void note_stop_adding_survivor_regions() {
926 _survivor_surv_rate_group->stop_adding_regions();
927 }
929 void record_survivor_regions(uint regions,
930 HeapRegion* head,
931 HeapRegion* tail) {
932 _recorded_survivor_regions = regions;
933 _recorded_survivor_head = head;
934 _recorded_survivor_tail = tail;
935 }
937 uint recorded_survivor_regions() {
938 return _recorded_survivor_regions;
939 }
941 void record_thread_age_table(ageTable* age_table) {
942 _survivors_age_table.merge_par(age_table);
943 }
945 void update_max_gc_locker_expansion();
947 // Calculates survivor space parameters.
948 void update_survivors_policy();
950 };
952 // This should move to some place more general...
954 // If we have "n" measurements, and we've kept track of their "sum" and the
955 // "sum_of_squares" of the measurements, this returns the variance of the
956 // sequence.
957 inline double variance(int n, double sum_of_squares, double sum) {
958 double n_d = (double)n;
959 double avg = sum/n_d;
960 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
961 }
963 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP