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 // every time 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 // Update the given values for minimum and maximum young gen length in regions
140 // given the number of heap regions depending on the kind of sizing algorithm.
141 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
142
143 public:
144 G1YoungGenSizer();
145 // Calculate the maximum length of the young gen given the number of regions
146 // depending on the sizing algorithm.
147 uint max_young_length(uint number_of_heap_regions);
148
149 void heap_size_changed(uint new_number_of_heap_regions);
150 uint min_desired_young_length() {
151 return _min_desired_young_length;
152 }
153 uint max_desired_young_length() {
154 return _max_desired_young_length;
155 }
156 bool adaptive_young_list_length() {
157 return _adaptive_size;
158 }
159 };
160
161 class G1CollectorPolicy: public CollectorPolicy {
162 private:
163 // either equal to the number of parallel threads, if ParallelGCThreads
164 // has been set, or 1 otherwise
165 int _parallel_gc_threads;
166
167 // The number of GC threads currently active.
168 uintx _no_of_gc_threads;
169
170 enum SomePrivateConstants {
171 NumPrevPausesForHeuristics = 10
172 };
173
174 G1MMUTracker* _mmu_tracker;
175
176 void initialize_flags();
177
178 CollectionSetChooser* _collectionSetChooser;
179
180 double _full_collection_start_sec;
181 uint _cur_collection_pause_used_regions_at_start;
182
183 // These exclude marking times.
184 TruncatedSeq* _recent_gc_times_ms;
185
186 TruncatedSeq* _concurrent_mark_remark_times_ms;
187 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
188
189 TraceGen0TimeData _trace_gen0_time_data;
190 TraceGen1TimeData _trace_gen1_time_data;
191
192 double _stop_world_start;
193
194 // indicates whether we are in young or mixed GC mode
195 bool _gcs_are_young;
196
197 uint _young_list_target_length;
198 uint _young_list_fixed_length;
199
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;
203
204 bool _last_gc_was_young;
205
206 bool _during_marking;
207 bool _in_marking_window;
208 bool _in_marking_window_im;
209
210 SurvRateGroup* _short_lived_surv_rate_group;
211 SurvRateGroup* _survivor_surv_rate_group;
212 // add here any more surv rate groups
213
214 double _gc_overhead_perc;
215
216 double _reserve_factor;
217 uint _reserve_regions;
218
219 bool during_marking() {
220 return _during_marking;
221 }
222
223 enum PredictionConstants {
224 TruncatedSeqLength = 10
225 };
226
227 TruncatedSeq* _alloc_rate_ms_seq;
228 double _prev_collection_pause_end_ms;
229
230 TruncatedSeq* _rs_length_diff_seq;
231 TruncatedSeq* _cost_per_card_ms_seq;
232 TruncatedSeq* _young_cards_per_entry_ratio_seq;
233 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
234 TruncatedSeq* _cost_per_entry_ms_seq;
235 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
236 TruncatedSeq* _cost_per_byte_ms_seq;
237 TruncatedSeq* _constant_other_time_ms_seq;
238 TruncatedSeq* _young_other_cost_per_region_ms_seq;
239 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
240
241 TruncatedSeq* _pending_cards_seq;
242 TruncatedSeq* _rs_lengths_seq;
243
244 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
245
246 G1YoungGenSizer* _young_gen_sizer;
247
248 uint _eden_cset_region_length;
249 uint _survivor_cset_region_length;
250 uint _old_cset_region_length;
251
252 void init_cset_region_lengths(uint eden_cset_region_length,
253 uint survivor_cset_region_length);
254
255 uint eden_cset_region_length() { return _eden_cset_region_length; }
256 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
257 uint old_cset_region_length() { return _old_cset_region_length; }
258
259 uint _free_regions_at_end_of_collection;
260
261 size_t _recorded_rs_lengths;
262 size_t _max_rs_lengths;
263 double _sigma;
264
265 size_t _rs_lengths_prediction;
266
267 double sigma() { return _sigma; }
268
269 // A function that prevents us putting too much stock in small sample
270 // sets. Returns a number between 2.0 and 1.0, depending on the number
271 // of samples. 5 or more samples yields one; fewer scales linearly from
272 // 2.0 at 1 sample to 1.0 at 5.
273 double confidence_factor(int samples) {
274 if (samples > 4) return 1.0;
275 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
276 }
277
278 double get_new_neg_prediction(TruncatedSeq* seq) {
279 return seq->davg() - sigma() * seq->dsd();
280 }
281
282 #ifndef PRODUCT
283 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
284 #endif // PRODUCT
285
286 void adjust_concurrent_refinement(double update_rs_time,
287 double update_rs_processed_buffers,
288 double goal_ms);
289
290 uintx no_of_gc_threads() { return _no_of_gc_threads; }
291 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
292
293 double _pause_time_target_ms;
294
295 size_t _pending_cards;
296
297 public:
298 // Accessors
299
300 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
301 hr->set_young();
302 hr->install_surv_rate_group(_short_lived_surv_rate_group);
303 hr->set_young_index_in_cset(young_index_in_cset);
304 }
305
306 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
307 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
308 hr->install_surv_rate_group(_survivor_surv_rate_group);
309 hr->set_young_index_in_cset(young_index_in_cset);
310 }
311
312 #ifndef PRODUCT
313 bool verify_young_ages();
314 #endif // PRODUCT
315
316 double get_new_prediction(TruncatedSeq* seq) {
317 return MAX2(seq->davg() + sigma() * seq->dsd(),
318 seq->davg() * confidence_factor(seq->num()));
319 }
320
321 void record_max_rs_lengths(size_t rs_lengths) {
322 _max_rs_lengths = rs_lengths;
323 }
324
325 size_t predict_rs_length_diff() {
326 return (size_t) get_new_prediction(_rs_length_diff_seq);
327 }
328
329 double predict_alloc_rate_ms() {
330 return get_new_prediction(_alloc_rate_ms_seq);
331 }
332
333 double predict_cost_per_card_ms() {
334 return get_new_prediction(_cost_per_card_ms_seq);
335 }
336
337 double predict_rs_update_time_ms(size_t pending_cards) {
338 return (double) pending_cards * predict_cost_per_card_ms();
339 }
340
341 double predict_young_cards_per_entry_ratio() {
342 return get_new_prediction(_young_cards_per_entry_ratio_seq);
343 }
344
345 double predict_mixed_cards_per_entry_ratio() {
346 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
347 return predict_young_cards_per_entry_ratio();
348 } else {
349 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
350 }
351 }
352
353 size_t predict_young_card_num(size_t rs_length) {
354 return (size_t) ((double) rs_length *
355 predict_young_cards_per_entry_ratio());
356 }
357
358 size_t predict_non_young_card_num(size_t rs_length) {
359 return (size_t) ((double) rs_length *
360 predict_mixed_cards_per_entry_ratio());
361 }
362
363 double predict_rs_scan_time_ms(size_t card_num) {
364 if (gcs_are_young()) {
365 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
366 } else {
367 return predict_mixed_rs_scan_time_ms(card_num);
368 }
369 }
370
371 double predict_mixed_rs_scan_time_ms(size_t card_num) {
372 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
373 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
374 } else {
375 return (double) (card_num *
376 get_new_prediction(_mixed_cost_per_entry_ms_seq));
377 }
378 }
379
380 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
381 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
382 return (1.1 * (double) bytes_to_copy) *
383 get_new_prediction(_cost_per_byte_ms_seq);
384 } else {
385 return (double) bytes_to_copy *
386 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
387 }
388 }
389
390 double predict_object_copy_time_ms(size_t bytes_to_copy) {
391 if (_in_marking_window && !_in_marking_window_im) {
392 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
393 } else {
394 return (double) bytes_to_copy *
395 get_new_prediction(_cost_per_byte_ms_seq);
396 }
397 }
398
399 double predict_constant_other_time_ms() {
400 return get_new_prediction(_constant_other_time_ms_seq);
401 }
402
403 double predict_young_other_time_ms(size_t young_num) {
404 return (double) young_num *
405 get_new_prediction(_young_other_cost_per_region_ms_seq);
406 }
407
408 double predict_non_young_other_time_ms(size_t non_young_num) {
409 return (double) non_young_num *
410 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
411 }
412
413 double predict_base_elapsed_time_ms(size_t pending_cards);
414 double predict_base_elapsed_time_ms(size_t pending_cards,
415 size_t scanned_cards);
416 size_t predict_bytes_to_copy(HeapRegion* hr);
417 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc);
418
419 void set_recorded_rs_lengths(size_t rs_lengths);
420
421 uint cset_region_length() { return young_cset_region_length() +
422 old_cset_region_length(); }
423 uint young_cset_region_length() { return eden_cset_region_length() +
424 survivor_cset_region_length(); }
425
426 double predict_survivor_regions_evac_time();
427
428 void cset_regions_freed() {
429 bool propagate = _last_gc_was_young && !_in_marking_window;
430 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
431 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
432 // also call it on any more surv rate groups
433 }
434
435 G1MMUTracker* mmu_tracker() {
436 return _mmu_tracker;
437 }
438
439 double max_pause_time_ms() {
440 return _mmu_tracker->max_gc_time() * 1000.0;
441 }
442
443 double predict_remark_time_ms() {
444 return get_new_prediction(_concurrent_mark_remark_times_ms);
445 }
446
447 double predict_cleanup_time_ms() {
448 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
449 }
450
451 // Returns an estimate of the survival rate of the region at yg-age
452 // "yg_age".
453 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
454 TruncatedSeq* seq = surv_rate_group->get_seq(age);
455 if (seq->num() == 0)
456 gclog_or_tty->print("BARF! age is %d", age);
457 guarantee( seq->num() > 0, "invariant" );
458 double pred = get_new_prediction(seq);
459 if (pred > 1.0)
460 pred = 1.0;
461 return pred;
462 }
463
464 double predict_yg_surv_rate(int age) {
465 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
466 }
467
468 double accum_yg_surv_rate_pred(int age) {
469 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
470 }
471
472 private:
473 // Statistics kept per GC stoppage, pause or full.
474 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
475
476 // Add a new GC of the given duration and end time to the record.
477 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
478
479 // The head of the list (via "next_in_collection_set()") representing the
480 // current collection set. Set from the incrementally built collection
481 // set at the start of the pause.
482 HeapRegion* _collection_set;
483
484 // The number of bytes in the collection set before the pause. Set from
485 // the incrementally built collection set at the start of an evacuation
486 // pause, and incremented in finalize_cset() when adding old regions
487 // (if any) to the collection set.
488 size_t _collection_set_bytes_used_before;
489
490 // The number of bytes copied during the GC.
491 size_t _bytes_copied_during_gc;
492
493 // The associated information that is maintained while the incremental
494 // collection set is being built with young regions. Used to populate
495 // the recorded info for the evacuation pause.
496
497 enum CSetBuildType {
498 Active, // We are actively building the collection set
499 Inactive // We are not actively building the collection set
500 };
501
502 CSetBuildType _inc_cset_build_state;
503
504 // The head of the incrementally built collection set.
505 HeapRegion* _inc_cset_head;
506
507 // The tail of the incrementally built collection set.
508 HeapRegion* _inc_cset_tail;
509
510 // The number of bytes in the incrementally built collection set.
511 // Used to set _collection_set_bytes_used_before at the start of
512 // an evacuation pause.
513 size_t _inc_cset_bytes_used_before;
514
515 // Used to record the highest end of heap region in collection set
516 HeapWord* _inc_cset_max_finger;
517
518 // The RSet lengths recorded for regions in the CSet. It is updated
519 // by the thread that adds a new region to the CSet. We assume that
520 // only one thread can be allocating a new CSet region (currently,
521 // it does so after taking the Heap_lock) hence no need to
522 // synchronize updates to this field.
523 size_t _inc_cset_recorded_rs_lengths;
524
525 // A concurrent refinement thread periodcially samples the young
526 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
527 // the RSets grow. Instead of having to syncronize updates to that
528 // field we accumulate them in this field and add it to
529 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
530 ssize_t _inc_cset_recorded_rs_lengths_diffs;
531
532 // The predicted elapsed time it will take to collect the regions in
533 // the CSet. This is updated by the thread that adds a new region to
534 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
535 // MT-safety assumptions.
536 double _inc_cset_predicted_elapsed_time_ms;
537
538 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
539 double _inc_cset_predicted_elapsed_time_ms_diffs;
540
541 // Stash a pointer to the g1 heap.
542 G1CollectedHeap* _g1;
543
544 G1GCPhaseTimes* _phase_times;
545
546 // The ratio of gc time to elapsed time, computed over recent pauses.
547 double _recent_avg_pause_time_ratio;
548
549 double recent_avg_pause_time_ratio() {
550 return _recent_avg_pause_time_ratio;
551 }
552
553 // At the end of a pause we check the heap occupancy and we decide
554 // whether we will start a marking cycle during the next pause. If
555 // we decide that we want to do that, we will set this parameter to
556 // true. So, this parameter will stay true between the end of a
557 // pause and the beginning of a subsequent pause (not necessarily
558 // the next one, see the comments on the next field) when we decide
559 // that we will indeed start a marking cycle and do the initial-mark
560 // work.
561 volatile bool _initiate_conc_mark_if_possible;
562
563 // If initiate_conc_mark_if_possible() is set at the beginning of a
564 // pause, it is a suggestion that the pause should start a marking
565 // cycle by doing the initial-mark work. However, it is possible
566 // that the concurrent marking thread is still finishing up the
567 // previous marking cycle (e.g., clearing the next marking
568 // bitmap). If that is the case we cannot start a new cycle and
569 // we'll have to wait for the concurrent marking thread to finish
570 // what it is doing. In this case we will postpone the marking cycle
571 // initiation decision for the next pause. When we eventually decide
572 // to start a cycle, we will set _during_initial_mark_pause which
573 // will stay true until the end of the initial-mark pause and it's
574 // the condition that indicates that a pause is doing the
575 // initial-mark work.
576 volatile bool _during_initial_mark_pause;
577
578 bool _last_young_gc;
579
580 // This set of variables tracks the collector efficiency, in order to
581 // determine whether we should initiate a new marking.
582 double _cur_mark_stop_world_time_ms;
583 double _mark_remark_start_sec;
584 double _mark_cleanup_start_sec;
585
586 // Update the young list target length either by setting it to the
587 // desired fixed value or by calculating it using G1's pause
588 // prediction model. If no rs_lengths parameter is passed, predict
589 // the RS lengths using the prediction model, otherwise use the
590 // given rs_lengths as the prediction.
591 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
592
593 // Calculate and return the minimum desired young list target
594 // length. This is the minimum desired young list length according
595 // to the user's inputs.
596 uint calculate_young_list_desired_min_length(uint base_min_length);
597
598 // Calculate and return the maximum desired young list target
599 // length. This is the maximum desired young list length according
600 // to the user's inputs.
601 uint calculate_young_list_desired_max_length();
602
603 // Calculate and return the maximum young list target length that
604 // can fit into the pause time goal. The parameters are: rs_lengths
605 // represent the prediction of how large the young RSet lengths will
606 // be, base_min_length is the alreay existing number of regions in
607 // the young list, min_length and max_length are the desired min and
608 // max young list length according to the user's inputs.
609 uint calculate_young_list_target_length(size_t rs_lengths,
610 uint base_min_length,
611 uint desired_min_length,
612 uint desired_max_length);
613
614 // Check whether a given young length (young_length) fits into the
615 // given target pause time and whether the prediction for the amount
616 // of objects to be copied for the given length will fit into the
617 // given free space (expressed by base_free_regions). It is used by
618 // calculate_young_list_target_length().
619 bool predict_will_fit(uint young_length, double base_time_ms,
620 uint base_free_regions, double target_pause_time_ms);
621
622 // Calculate the minimum number of old regions we'll add to the CSet
623 // during a mixed GC.
624 uint calc_min_old_cset_length();
625
626 // Calculate the maximum number of old regions we'll add to the CSet
627 // during a mixed GC.
628 uint calc_max_old_cset_length();
629
630 // Returns the given amount of uncollected reclaimable space
631 // as a percentage of the current heap capacity.
632 double reclaimable_bytes_perc(size_t reclaimable_bytes);
633
634 public:
635
636 G1CollectorPolicy();
637
638 virtual G1CollectorPolicy* as_g1_policy() { return this; }
639
640 virtual CollectorPolicy::Name kind() {
641 return CollectorPolicy::G1CollectorPolicyKind;
642 }
643
644 G1GCPhaseTimes* phase_times() const { return _phase_times; }
645
646 // Check the current value of the young list RSet lengths and
647 // compare it against the last prediction. If the current value is
648 // higher, recalculate the young list target length prediction.
649 void revise_young_list_target_length_if_necessary();
650
651 // This should be called after the heap is resized.
652 void record_new_heap_size(uint new_number_of_regions);
653
654 void init();
655
656 // Create jstat counters for the policy.
657 virtual void initialize_gc_policy_counters();
658
659 virtual HeapWord* mem_allocate_work(size_t size,
660 bool is_tlab,
661 bool* gc_overhead_limit_was_exceeded);
662
663 // This method controls how a collector handles one or more
664 // of its generations being fully allocated.
665 virtual HeapWord* satisfy_failed_allocation(size_t size,
666 bool is_tlab);
667
668 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
669
670 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
671
672 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
673
674 // Record the start and end of an evacuation pause.
675 void record_collection_pause_start(double start_time_sec);
676 void record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info);
677
678 // Record the start and end of a full collection.
679 void record_full_collection_start();
680 void record_full_collection_end();
681
682 // Must currently be called while the world is stopped.
683 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
684
685 // Record start and end of remark.
686 void record_concurrent_mark_remark_start();
687 void record_concurrent_mark_remark_end();
688
689 // Record start, end, and completion of cleanup.
690 void record_concurrent_mark_cleanup_start();
691 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
692 void record_concurrent_mark_cleanup_completed();
693
694 // Records the information about the heap size for reporting in
695 // print_detailed_heap_transition
696 void record_heap_size_info_at_start(bool full);
697
698 // Print heap sizing transition (with less and more detail).
699 void print_heap_transition();
700 void print_detailed_heap_transition(bool full = false);
701
702 void record_stop_world_start();
703 void record_concurrent_pause();
704
705 // Record how much space we copied during a GC. This is typically
706 // called when a GC alloc region is being retired.
707 void record_bytes_copied_during_gc(size_t bytes) {
708 _bytes_copied_during_gc += bytes;
709 }
710
711 // The amount of space we copied during a GC.
712 size_t bytes_copied_during_gc() {
713 return _bytes_copied_during_gc;
714 }
715
716 // Determine whether there are candidate regions so that the
717 // next GC should be mixed. The two action strings are used
718 // in the ergo output when the method returns true or false.
719 bool next_gc_should_be_mixed(const char* true_action_str,
720 const char* false_action_str);
721
722 // Choose a new collection set. Marks the chosen regions as being
723 // "in_collection_set", and links them together. The head and number of
724 // the collection set are available via access methods.
725 void finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info);
726
727 // The head of the list (via "next_in_collection_set()") representing the
728 // current collection set.
729 HeapRegion* collection_set() { return _collection_set; }
730
731 void clear_collection_set() { _collection_set = NULL; }
732
733 // Add old region "hr" to the CSet.
734 void add_old_region_to_cset(HeapRegion* hr);
735
736 // Incremental CSet Support
737
738 // The head of the incrementally built collection set.
739 HeapRegion* inc_cset_head() { return _inc_cset_head; }
740
741 // The tail of the incrementally built collection set.
742 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
743
744 // Initialize incremental collection set info.
745 void start_incremental_cset_building();
746
747 // Perform any final calculations on the incremental CSet fields
748 // before we can use them.
749 void finalize_incremental_cset_building();
750
751 void clear_incremental_cset() {
752 _inc_cset_head = NULL;
753 _inc_cset_tail = NULL;
754 }
755
756 // Stop adding regions to the incremental collection set
757 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
758
759 // Add information about hr to the aggregated information for the
760 // incrementally built collection set.
761 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
762
763 // Update information about hr in the aggregated information for
764 // the incrementally built collection set.
765 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
766
767 private:
768 // Update the incremental cset information when adding a region
769 // (should not be called directly).
770 void add_region_to_incremental_cset_common(HeapRegion* hr);
771
772 public:
773 // Add hr to the LHS of the incremental collection set.
774 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
775
776 // Add hr to the RHS of the incremental collection set.
777 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
778
779 #ifndef PRODUCT
780 void print_collection_set(HeapRegion* list_head, outputStream* st);
781 #endif // !PRODUCT
782
783 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
784 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
785 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
786
787 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
788 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
789 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
790
791 // This sets the initiate_conc_mark_if_possible() flag to start a
792 // new cycle, as long as we are not already in one. It's best if it
793 // is called during a safepoint when the test whether a cycle is in
794 // progress or not is stable.
795 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
796
797 // This is called at the very beginning of an evacuation pause (it
798 // has to be the first thing that the pause does). If
799 // initiate_conc_mark_if_possible() is true, and the concurrent
800 // marking thread has completed its work during the previous cycle,
801 // it will set during_initial_mark_pause() to so that the pause does
802 // the initial-mark work and start a marking cycle.
803 void decide_on_conc_mark_initiation();
804
805 // If an expansion would be appropriate, because recent GC overhead had
806 // exceeded the desired limit, return an amount to expand by.
807 size_t expansion_amount();
808
809 // Print tracing information.
810 void print_tracing_info() const;
811
812 // Print stats on young survival ratio
813 void print_yg_surv_rate_info() const;
814
815 void finished_recalculating_age_indexes(bool is_survivors) {
816 if (is_survivors) {
817 _survivor_surv_rate_group->finished_recalculating_age_indexes();
818 } else {
819 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
820 }
821 // do that for any other surv rate groups
822 }
823
824 bool is_young_list_full() {
825 uint young_list_length = _g1->young_list()->length();
826 uint young_list_target_length = _young_list_target_length;
827 return young_list_length >= young_list_target_length;
828 }
829
830 bool can_expand_young_list() {
831 uint young_list_length = _g1->young_list()->length();
832 uint young_list_max_length = _young_list_max_length;
833 return young_list_length < young_list_max_length;
834 }
835
836 uint young_list_max_length() {
837 return _young_list_max_length;
838 }
839
840 bool gcs_are_young() {
841 return _gcs_are_young;
842 }
843 void set_gcs_are_young(bool gcs_are_young) {
844 _gcs_are_young = gcs_are_young;
845 }
846
847 bool adaptive_young_list_length() {
848 return _young_gen_sizer->adaptive_young_list_length();
849 }
850
851 private:
852 //
853 // Survivor regions policy.
854 //
855
856 // Current tenuring threshold, set to 0 if the collector reaches the
857 // maximum amount of survivors regions.
858 uint _tenuring_threshold;
859
860 // The limit on the number of regions allocated for survivors.
861 uint _max_survivor_regions;
862
863 // For reporting purposes.
864 // The value of _heap_bytes_before_gc is also used to calculate
865 // the cost of copying.
866
867 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC
868 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC
869 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC
870 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC
871
872 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC
873 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC
874
875 // The amount of survivor regions after a collection.
876 uint _recorded_survivor_regions;
877 // List of survivor regions.
878 HeapRegion* _recorded_survivor_head;
879 HeapRegion* _recorded_survivor_tail;
880
881 ageTable _survivors_age_table;
882
883 public:
884 uint tenuring_threshold() const { return _tenuring_threshold; }
885
886 inline GCAllocPurpose
887 evacuation_destination(HeapRegion* src_region, uint age, size_t word_sz) {
888 if (age < _tenuring_threshold && src_region->is_young()) {
889 return GCAllocForSurvived;
890 } else {
891 return GCAllocForTenured;
892 }
893 }
894
895 inline bool track_object_age(GCAllocPurpose purpose) {
896 return purpose == GCAllocForSurvived;
897 }
898
899 static const uint REGIONS_UNLIMITED = (uint) -1;
900
901 uint max_regions(int purpose);
902
903 // The limit on regions for a particular purpose is reached.
904 void note_alloc_region_limit_reached(int purpose) {
905 if (purpose == GCAllocForSurvived) {
906 _tenuring_threshold = 0;
907 }
908 }
909
910 void note_start_adding_survivor_regions() {
911 _survivor_surv_rate_group->start_adding_regions();
912 }
913
914 void note_stop_adding_survivor_regions() {
915 _survivor_surv_rate_group->stop_adding_regions();
916 }
917
918 void record_survivor_regions(uint regions,
919 HeapRegion* head,
920 HeapRegion* tail) {
921 _recorded_survivor_regions = regions;
922 _recorded_survivor_head = head;
923 _recorded_survivor_tail = tail;
924 }
925
926 uint recorded_survivor_regions() {
927 return _recorded_survivor_regions;
928 }
929
930 void record_thread_age_table(ageTable* age_table) {
931 _survivors_age_table.merge_par(age_table);
932 }
933
934 void update_max_gc_locker_expansion();
935
936 // Calculates survivor space parameters.
937 void update_survivors_policy();
938
939 virtual void post_heap_initialize();
940 };
941
942 // This should move to some place more general...
943
944 // If we have "n" measurements, and we've kept track of their "sum" and the
945 // "sum_of_squares" of the measurements, this returns the variance of the
946 // sequence.
947 inline double variance(int n, double sum_of_squares, double sum) {
948 double n_d = (double)n;
949 double avg = sum/n_d;
950 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
951 }
952
953 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP