1 /*
2 * Copyright (c) 2001, 2013, 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 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
27
28 #include "gc_implementation/g1/collectionSetChooser.hpp"
29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 #include "memory/collectorPolicy.hpp"
31
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.
36
37 class HeapRegion;
38 class CollectionSetChooser;
39 class G1GCPhaseTimes;
40
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;
48
49 NumberSeq _all_stop_world_times_ms;
50 NumberSeq _all_yield_times_ms;
51
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;
64
65 void print_summary(const char* str, const NumberSeq* seq) const;
66 void print_summary_sd(const char* str, const NumberSeq* seq) const;
67
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 };
77
78 class TraceGen1TimeData : public CHeapObj<mtGC> {
79 private:
80 NumberSeq _all_full_gc_times;
81
82 public:
83 void record_full_collection(double full_gc_time_ms);
84 void print() const;
85 };
86
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 G1NewSizePercent
98 // and G1MaxNewSizePercent of the heap size. This means that every time
99 // the heap size changes, the limits for the young gen size will be
100 // recalculated.
101 //
102 // If only -XX:NewSize is set we should use the specified value as the
103 // minimum size for young gen. Still using G1MaxNewSizePercent of the
104 // 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 G1NewSizePercent of the heap
108 // 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);
138
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 };
152
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;
158
159 // The number of GC threads currently active.
160 uintx _no_of_gc_threads;
161
162 enum SomePrivateConstants {
163 NumPrevPausesForHeuristics = 10
164 };
165
166 G1MMUTracker* _mmu_tracker;
167
168 void initialize_flags();
169
170 void initialize_all() {
171 initialize_flags();
172 initialize_size_info();
173 }
174
175 CollectionSetChooser* _collectionSetChooser;
176
177 double _full_collection_start_sec;
178 uint _cur_collection_pause_used_regions_at_start;
179
180 // These exclude marking times.
181 TruncatedSeq* _recent_gc_times_ms;
182
183 TruncatedSeq* _concurrent_mark_remark_times_ms;
184 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
185
186 TraceGen0TimeData _trace_gen0_time_data;
187 TraceGen1TimeData _trace_gen1_time_data;
188
189 double _stop_world_start;
190
191 // indicates whether we are in young or mixed GC mode
192 bool _gcs_are_young;
193
194 uint _young_list_target_length;
195 uint _young_list_fixed_length;
196
197 // The max number of regions we can extend the eden by while the GC
198 // locker is active. This should be >= _young_list_target_length;
199 uint _young_list_max_length;
200
201 bool _last_gc_was_young;
202
203 bool _during_marking;
204 bool _in_marking_window;
205 bool _in_marking_window_im;
206
207 SurvRateGroup* _short_lived_surv_rate_group;
208 SurvRateGroup* _survivor_surv_rate_group;
209 // add here any more surv rate groups
210
211 double _gc_overhead_perc;
212
213 double _reserve_factor;
214 uint _reserve_regions;
215
216 bool during_marking() {
217 return _during_marking;
218 }
219
220 enum PredictionConstants {
221 TruncatedSeqLength = 10
222 };
223
224 TruncatedSeq* _alloc_rate_ms_seq;
225 double _prev_collection_pause_end_ms;
226
227 TruncatedSeq* _rs_length_diff_seq;
228 TruncatedSeq* _cost_per_card_ms_seq;
229 TruncatedSeq* _young_cards_per_entry_ratio_seq;
230 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
231 TruncatedSeq* _cost_per_entry_ms_seq;
232 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
233 TruncatedSeq* _cost_per_byte_ms_seq;
234 TruncatedSeq* _constant_other_time_ms_seq;
235 TruncatedSeq* _young_other_cost_per_region_ms_seq;
236 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
237
238 TruncatedSeq* _pending_cards_seq;
239 TruncatedSeq* _rs_lengths_seq;
240
241 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
242
243 G1YoungGenSizer* _young_gen_sizer;
244
245 uint _eden_cset_region_length;
246 uint _survivor_cset_region_length;
247 uint _old_cset_region_length;
248
249 void init_cset_region_lengths(uint eden_cset_region_length,
250 uint survivor_cset_region_length);
251
252 uint eden_cset_region_length() { return _eden_cset_region_length; }
253 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
254 uint old_cset_region_length() { return _old_cset_region_length; }
255
256 uint _free_regions_at_end_of_collection;
257
258 size_t _recorded_rs_lengths;
259 size_t _max_rs_lengths;
260 double _sigma;
261
262 size_t _rs_lengths_prediction;
263
264 double sigma() { return _sigma; }
265
266 // A function that prevents us putting too much stock in small sample
267 // sets. Returns a number between 2.0 and 1.0, depending on the number
268 // of samples. 5 or more samples yields one; fewer scales linearly from
269 // 2.0 at 1 sample to 1.0 at 5.
270 double confidence_factor(int samples) {
271 if (samples > 4) return 1.0;
272 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
273 }
274
275 double get_new_neg_prediction(TruncatedSeq* seq) {
276 return seq->davg() - sigma() * seq->dsd();
277 }
278
279 #ifndef PRODUCT
280 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
281 #endif // PRODUCT
282
283 void adjust_concurrent_refinement(double update_rs_time,
284 double update_rs_processed_buffers,
285 double goal_ms);
286
287 uintx no_of_gc_threads() { return _no_of_gc_threads; }
288 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
289
290 double _pause_time_target_ms;
291
292 size_t _pending_cards;
293
294 public:
295 // Accessors
296
297 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
298 hr->set_young();
299 hr->install_surv_rate_group(_short_lived_surv_rate_group);
300 hr->set_young_index_in_cset(young_index_in_cset);
301 }
302
303 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
304 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
305 hr->install_surv_rate_group(_survivor_surv_rate_group);
306 hr->set_young_index_in_cset(young_index_in_cset);
307 }
308
309 #ifndef PRODUCT
310 bool verify_young_ages();
311 #endif // PRODUCT
312
313 double get_new_prediction(TruncatedSeq* seq) {
314 return MAX2(seq->davg() + sigma() * seq->dsd(),
315 seq->davg() * confidence_factor(seq->num()));
316 }
317
318 void record_max_rs_lengths(size_t rs_lengths) {
319 _max_rs_lengths = rs_lengths;
320 }
321
322 size_t predict_rs_length_diff() {
323 return (size_t) get_new_prediction(_rs_length_diff_seq);
324 }
325
326 double predict_alloc_rate_ms() {
327 return get_new_prediction(_alloc_rate_ms_seq);
328 }
329
330 double predict_cost_per_card_ms() {
331 return get_new_prediction(_cost_per_card_ms_seq);
332 }
333
334 double predict_rs_update_time_ms(size_t pending_cards) {
335 return (double) pending_cards * predict_cost_per_card_ms();
336 }
337
338 double predict_young_cards_per_entry_ratio() {
339 return get_new_prediction(_young_cards_per_entry_ratio_seq);
340 }
341
342 double predict_mixed_cards_per_entry_ratio() {
343 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
344 return predict_young_cards_per_entry_ratio();
345 } else {
346 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
347 }
348 }
349
350 size_t predict_young_card_num(size_t rs_length) {
351 return (size_t) ((double) rs_length *
352 predict_young_cards_per_entry_ratio());
353 }
354
355 size_t predict_non_young_card_num(size_t rs_length) {
356 return (size_t) ((double) rs_length *
357 predict_mixed_cards_per_entry_ratio());
358 }
359
360 double predict_rs_scan_time_ms(size_t card_num) {
361 if (gcs_are_young()) {
362 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
363 } else {
364 return predict_mixed_rs_scan_time_ms(card_num);
365 }
366 }
367
368 double predict_mixed_rs_scan_time_ms(size_t card_num) {
369 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
370 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
371 } else {
372 return (double) (card_num *
373 get_new_prediction(_mixed_cost_per_entry_ms_seq));
374 }
375 }
376
377 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
378 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
379 return (1.1 * (double) bytes_to_copy) *
380 get_new_prediction(_cost_per_byte_ms_seq);
381 } else {
382 return (double) bytes_to_copy *
383 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
384 }
385 }
386
387 double predict_object_copy_time_ms(size_t bytes_to_copy) {
388 if (_in_marking_window && !_in_marking_window_im) {
389 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
390 } else {
391 return (double) bytes_to_copy *
392 get_new_prediction(_cost_per_byte_ms_seq);
393 }
394 }
395
396 double predict_constant_other_time_ms() {
397 return get_new_prediction(_constant_other_time_ms_seq);
398 }
399
400 double predict_young_other_time_ms(size_t young_num) {
401 return (double) young_num *
402 get_new_prediction(_young_other_cost_per_region_ms_seq);
403 }
404
405 double predict_non_young_other_time_ms(size_t non_young_num) {
406 return (double) non_young_num *
407 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
408 }
409
410 double predict_base_elapsed_time_ms(size_t pending_cards);
411 double predict_base_elapsed_time_ms(size_t pending_cards,
412 size_t scanned_cards);
413 size_t predict_bytes_to_copy(HeapRegion* hr);
414 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc);
415
416 void set_recorded_rs_lengths(size_t rs_lengths);
417
418 uint cset_region_length() { return young_cset_region_length() +
419 old_cset_region_length(); }
420 uint young_cset_region_length() { return eden_cset_region_length() +
421 survivor_cset_region_length(); }
422
423 double predict_survivor_regions_evac_time();
424
425 void cset_regions_freed() {
426 bool propagate = _last_gc_was_young && !_in_marking_window;
427 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
428 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
429 // also call it on any more surv rate groups
430 }
431
432 G1MMUTracker* mmu_tracker() {
433 return _mmu_tracker;
434 }
435
436 double max_pause_time_ms() {
437 return _mmu_tracker->max_gc_time() * 1000.0;
438 }
439
440 double predict_remark_time_ms() {
441 return get_new_prediction(_concurrent_mark_remark_times_ms);
442 }
443
444 double predict_cleanup_time_ms() {
445 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
446 }
447
448 // Returns an estimate of the survival rate of the region at yg-age
449 // "yg_age".
450 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
451 TruncatedSeq* seq = surv_rate_group->get_seq(age);
452 if (seq->num() == 0)
453 gclog_or_tty->print("BARF! age is %d", age);
454 guarantee( seq->num() > 0, "invariant" );
455 double pred = get_new_prediction(seq);
456 if (pred > 1.0)
457 pred = 1.0;
458 return pred;
459 }
460
461 double predict_yg_surv_rate(int age) {
462 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
463 }
464
465 double accum_yg_surv_rate_pred(int age) {
466 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
467 }
468
469 private:
470 // Statistics kept per GC stoppage, pause or full.
471 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
472
473 // Add a new GC of the given duration and end time to the record.
474 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
475
476 // The head of the list (via "next_in_collection_set()") representing the
477 // current collection set. Set from the incrementally built collection
478 // set at the start of the pause.
479 HeapRegion* _collection_set;
480
481 // The number of bytes in the collection set before the pause. Set from
482 // the incrementally built collection set at the start of an evacuation
483 // pause, and incremented in finalize_cset() when adding old regions
484 // (if any) to the collection set.
485 size_t _collection_set_bytes_used_before;
486
487 // The number of bytes copied during the GC.
488 size_t _bytes_copied_during_gc;
489
490 // The associated information that is maintained while the incremental
491 // collection set is being built with young regions. Used to populate
492 // the recorded info for the evacuation pause.
493
494 enum CSetBuildType {
495 Active, // We are actively building the collection set
496 Inactive // We are not actively building the collection set
497 };
498
499 CSetBuildType _inc_cset_build_state;
500
501 // The head of the incrementally built collection set.
502 HeapRegion* _inc_cset_head;
503
504 // The tail of the incrementally built collection set.
505 HeapRegion* _inc_cset_tail;
506
507 // The number of bytes in the incrementally built collection set.
508 // Used to set _collection_set_bytes_used_before at the start of
509 // an evacuation pause.
510 size_t _inc_cset_bytes_used_before;
511
512 // Used to record the highest end of heap region in collection set
513 HeapWord* _inc_cset_max_finger;
514
515 // The RSet lengths recorded for regions in the CSet. It is updated
516 // by the thread that adds a new region to the CSet. We assume that
517 // only one thread can be allocating a new CSet region (currently,
518 // it does so after taking the Heap_lock) hence no need to
519 // synchronize updates to this field.
520 size_t _inc_cset_recorded_rs_lengths;
521
522 // A concurrent refinement thread periodcially samples the young
523 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
524 // the RSets grow. Instead of having to syncronize updates to that
525 // field we accumulate them in this field and add it to
526 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
527 ssize_t _inc_cset_recorded_rs_lengths_diffs;
528
529 // The predicted elapsed time it will take to collect the regions in
530 // the CSet. This is updated by the thread that adds a new region to
531 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
532 // MT-safety assumptions.
533 double _inc_cset_predicted_elapsed_time_ms;
534
535 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
536 double _inc_cset_predicted_elapsed_time_ms_diffs;
537
538 // Stash a pointer to the g1 heap.
539 G1CollectedHeap* _g1;
540
541 G1GCPhaseTimes* _phase_times;
542
543 // The ratio of gc time to elapsed time, computed over recent pauses.
544 double _recent_avg_pause_time_ratio;
545
546 double recent_avg_pause_time_ratio() {
547 return _recent_avg_pause_time_ratio;
548 }
549
550 // At the end of a pause we check the heap occupancy and we decide
551 // whether we will start a marking cycle during the next pause. If
552 // we decide that we want to do that, we will set this parameter to
553 // true. So, this parameter will stay true between the end of a
554 // pause and the beginning of a subsequent pause (not necessarily
555 // the next one, see the comments on the next field) when we decide
556 // that we will indeed start a marking cycle and do the initial-mark
557 // work.
558 volatile bool _initiate_conc_mark_if_possible;
559
560 // If initiate_conc_mark_if_possible() is set at the beginning of a
561 // pause, it is a suggestion that the pause should start a marking
562 // cycle by doing the initial-mark work. However, it is possible
563 // that the concurrent marking thread is still finishing up the
564 // previous marking cycle (e.g., clearing the next marking
565 // bitmap). If that is the case we cannot start a new cycle and
566 // we'll have to wait for the concurrent marking thread to finish
567 // what it is doing. In this case we will postpone the marking cycle
568 // initiation decision for the next pause. When we eventually decide
569 // to start a cycle, we will set _during_initial_mark_pause which
570 // will stay true until the end of the initial-mark pause and it's
571 // the condition that indicates that a pause is doing the
572 // initial-mark work.
573 volatile bool _during_initial_mark_pause;
574
575 bool _last_young_gc;
576
577 // This set of variables tracks the collector efficiency, in order to
578 // determine whether we should initiate a new marking.
579 double _cur_mark_stop_world_time_ms;
580 double _mark_remark_start_sec;
581 double _mark_cleanup_start_sec;
582
583 // Update the young list target length either by setting it to the
584 // desired fixed value or by calculating it using G1's pause
585 // prediction model. If no rs_lengths parameter is passed, predict
586 // the RS lengths using the prediction model, otherwise use the
587 // given rs_lengths as the prediction.
588 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
589
590 // Calculate and return the minimum desired young list target
591 // length. This is the minimum desired young list length according
592 // to the user's inputs.
593 uint calculate_young_list_desired_min_length(uint base_min_length);
594
595 // Calculate and return the maximum desired young list target
596 // length. This is the maximum desired young list length according
597 // to the user's inputs.
598 uint calculate_young_list_desired_max_length();
599
600 // Calculate and return the maximum young list target length that
601 // can fit into the pause time goal. The parameters are: rs_lengths
602 // represent the prediction of how large the young RSet lengths will
603 // be, base_min_length is the alreay existing number of regions in
604 // the young list, min_length and max_length are the desired min and
605 // max young list length according to the user's inputs.
606 uint calculate_young_list_target_length(size_t rs_lengths,
607 uint base_min_length,
608 uint desired_min_length,
609 uint desired_max_length);
610
611 // Check whether a given young length (young_length) fits into the
612 // given target pause time and whether the prediction for the amount
613 // of objects to be copied for the given length will fit into the
614 // given free space (expressed by base_free_regions). It is used by
615 // calculate_young_list_target_length().
616 bool predict_will_fit(uint young_length, double base_time_ms,
617 uint base_free_regions, double target_pause_time_ms);
618
619 // Calculate the minimum number of old regions we'll add to the CSet
620 // during a mixed GC.
621 uint calc_min_old_cset_length();
622
623 // Calculate the maximum number of old regions we'll add to the CSet
624 // during a mixed GC.
625 uint calc_max_old_cset_length();
626
627 // Returns the given amount of uncollected reclaimable space
628 // as a percentage of the current heap capacity.
629 double reclaimable_bytes_perc(size_t reclaimable_bytes);
630
631 public:
632
633 G1CollectorPolicy();
634
635 virtual G1CollectorPolicy* as_g1_policy() { return this; }
636
637 virtual CollectorPolicy::Name kind() {
638 return CollectorPolicy::G1CollectorPolicyKind;
639 }
640
641 G1GCPhaseTimes* phase_times() const { return _phase_times; }
642
643 // Check the current value of the young list RSet lengths and
644 // compare it against the last prediction. If the current value is
645 // higher, recalculate the young list target length prediction.
646 void revise_young_list_target_length_if_necessary();
647
648 // This should be called after the heap is resized.
649 void record_new_heap_size(uint new_number_of_regions);
650
651 void init();
652
653 // Create jstat counters for the policy.
654 virtual void initialize_gc_policy_counters();
655
656 virtual HeapWord* mem_allocate_work(size_t size,
657 bool is_tlab,
658 bool* gc_overhead_limit_was_exceeded);
659
660 // This method controls how a collector handles one or more
661 // of its generations being fully allocated.
662 virtual HeapWord* satisfy_failed_allocation(size_t size,
663 bool is_tlab);
664
665 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
666
667 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
668
669 // Record the start and end of an evacuation pause.
670 void record_collection_pause_start(double start_time_sec);
671 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info);
672
673 // Record the start and end of a full collection.
674 void record_full_collection_start();
675 void record_full_collection_end();
676
677 // Must currently be called while the world is stopped.
678 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
679
680 // Record start and end of remark.
681 void record_concurrent_mark_remark_start();
682 void record_concurrent_mark_remark_end();
683
684 // Record start, end, and completion of cleanup.
685 void record_concurrent_mark_cleanup_start();
686 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
687 void record_concurrent_mark_cleanup_completed();
688
689 // Records the information about the heap size for reporting in
690 // print_detailed_heap_transition
691 void record_heap_size_info_at_start(bool full);
692
693 // Print heap sizing transition (with less and more detail).
694 void print_heap_transition();
695 void print_detailed_heap_transition(bool full = false);
696
697 void record_stop_world_start();
698 void record_concurrent_pause();
699
700 // Record how much space we copied during a GC. This is typically
701 // called when a GC alloc region is being retired.
702 void record_bytes_copied_during_gc(size_t bytes) {
703 _bytes_copied_during_gc += bytes;
704 }
705
706 // The amount of space we copied during a GC.
707 size_t bytes_copied_during_gc() {
708 return _bytes_copied_during_gc;
709 }
710
711 // Determine whether there are candidate regions so that the
712 // next GC should be mixed. The two action strings are used
713 // in the ergo output when the method returns true or false.
714 bool next_gc_should_be_mixed(const char* true_action_str,
715 const char* false_action_str);
716
717 // Choose a new collection set. Marks the chosen regions as being
718 // "in_collection_set", and links them together. The head and number of
719 // the collection set are available via access methods.
720 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info);
721
722 // The head of the list (via "next_in_collection_set()") representing the
723 // current collection set.
724 HeapRegion* collection_set() { return _collection_set; }
725
726 void clear_collection_set() { _collection_set = NULL; }
727
728 // Add old region "hr" to the CSet.
729 void add_old_region_to_cset(HeapRegion* hr);
730
731 // Incremental CSet Support
732
733 // The head of the incrementally built collection set.
734 HeapRegion* inc_cset_head() { return _inc_cset_head; }
735
736 // The tail of the incrementally built collection set.
737 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
738
739 // Initialize incremental collection set info.
740 void start_incremental_cset_building();
741
742 // Perform any final calculations on the incremental CSet fields
743 // before we can use them.
744 void finalize_incremental_cset_building();
745
746 void clear_incremental_cset() {
747 _inc_cset_head = NULL;
748 _inc_cset_tail = NULL;
749 }
750
751 // Stop adding regions to the incremental collection set
752 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
753
754 // Add information about hr to the aggregated information for the
755 // incrementally built collection set.
756 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
757
758 // Update information about hr in the aggregated information for
759 // the incrementally built collection set.
760 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
761
762 private:
763 // Update the incremental cset information when adding a region
764 // (should not be called directly).
765 void add_region_to_incremental_cset_common(HeapRegion* hr);
766
767 public:
768 // Add hr to the LHS of the incremental collection set.
769 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
770
771 // Add hr to the RHS of the incremental collection set.
772 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
773
774 #ifndef PRODUCT
775 void print_collection_set(HeapRegion* list_head, outputStream* st);
776 #endif // !PRODUCT
777
778 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
779 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
780 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
781
782 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
783 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
784 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
785
786 // This sets the initiate_conc_mark_if_possible() flag to start a
787 // new cycle, as long as we are not already in one. It's best if it
788 // is called during a safepoint when the test whether a cycle is in
789 // progress or not is stable.
790 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
791
792 // This is called at the very beginning of an evacuation pause (it
793 // has to be the first thing that the pause does). If
794 // initiate_conc_mark_if_possible() is true, and the concurrent
795 // marking thread has completed its work during the previous cycle,
796 // it will set during_initial_mark_pause() to so that the pause does
797 // the initial-mark work and start a marking cycle.
798 void decide_on_conc_mark_initiation();
799
800 // If an expansion would be appropriate, because recent GC overhead had
801 // exceeded the desired limit, return an amount to expand by.
802 size_t expansion_amount();
803
804 // Print tracing information.
805 void print_tracing_info() const;
806
807 // Print stats on young survival ratio
808 void print_yg_surv_rate_info() const;
809
810 void finished_recalculating_age_indexes(bool is_survivors) {
811 if (is_survivors) {
812 _survivor_surv_rate_group->finished_recalculating_age_indexes();
813 } else {
814 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
815 }
816 // do that for any other surv rate groups
817 }
818
819 bool is_young_list_full() {
820 uint young_list_length = _g1->young_list()->length();
821 uint young_list_target_length = _young_list_target_length;
822 return young_list_length >= young_list_target_length;
823 }
824
825 bool can_expand_young_list() {
826 uint young_list_length = _g1->young_list()->length();
827 uint young_list_max_length = _young_list_max_length;
828 return young_list_length < young_list_max_length;
829 }
830
831 uint young_list_max_length() {
832 return _young_list_max_length;
833 }
834
835 bool gcs_are_young() {
836 return _gcs_are_young;
837 }
838 void set_gcs_are_young(bool gcs_are_young) {
839 _gcs_are_young = gcs_are_young;
840 }
841
842 bool adaptive_young_list_length() {
843 return _young_gen_sizer->adaptive_young_list_length();
844 }
845
846 private:
847 //
848 // Survivor regions policy.
849 //
850
851 // Current tenuring threshold, set to 0 if the collector reaches the
852 // maximum amount of survivors regions.
853 uint _tenuring_threshold;
854
855 // The limit on the number of regions allocated for survivors.
856 uint _max_survivor_regions;
857
858 // For reporting purposes.
859 // The value of _heap_bytes_before_gc is also used to calculate
860 // the cost of copying.
861
862 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC
863 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC
864 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC
865 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC
866
867 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC
868 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC
869
870 // The amount of survivor regions after a collection.
871 uint _recorded_survivor_regions;
872 // List of survivor regions.
873 HeapRegion* _recorded_survivor_head;
874 HeapRegion* _recorded_survivor_tail;
875
876 ageTable _survivors_age_table;
877
878 public:
879 uint tenuring_threshold() const { return _tenuring_threshold; }
880
881 inline GCAllocPurpose
882 evacuation_destination(HeapRegion* src_region, uint age, size_t word_sz) {
883 if (age < _tenuring_threshold && src_region->is_young()) {
884 return GCAllocForSurvived;
885 } else {
886 return GCAllocForTenured;
887 }
888 }
889
890 inline bool track_object_age(GCAllocPurpose purpose) {
891 return purpose == GCAllocForSurvived;
892 }
893
894 static const uint REGIONS_UNLIMITED = (uint) -1;
895
896 uint max_regions(int purpose);
897
898 // The limit on regions for a particular purpose is reached.
899 void note_alloc_region_limit_reached(int purpose) {
900 if (purpose == GCAllocForSurvived) {
901 _tenuring_threshold = 0;
902 }
903 }
904
905 void note_start_adding_survivor_regions() {
906 _survivor_surv_rate_group->start_adding_regions();
907 }
908
909 void note_stop_adding_survivor_regions() {
910 _survivor_surv_rate_group->stop_adding_regions();
911 }
912
913 void record_survivor_regions(uint regions,
914 HeapRegion* head,
915 HeapRegion* tail) {
916 _recorded_survivor_regions = regions;
917 _recorded_survivor_head = head;
918 _recorded_survivor_tail = tail;
919 }
920
921 uint recorded_survivor_regions() {
922 return _recorded_survivor_regions;
923 }
924
925 void record_thread_age_table(ageTable* age_table) {
926 _survivors_age_table.merge_par(age_table);
927 }
928
929 void update_max_gc_locker_expansion();
930
931 // Calculates survivor space parameters.
932 void update_survivors_policy();
933
934 };
935
936 // This should move to some place more general...
937
938 // If we have "n" measurements, and we've kept track of their "sum" and the
939 // "sum_of_squares" of the measurements, this returns the variance of the
940 // sequence.
941 inline double variance(int n, double sum_of_squares, double sum) {
942 double n_d = (double)n;
943 double avg = sum/n_d;
944 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
945 }
946
947 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP