1 /*
2 * Copyright (c) 2001, 2015, 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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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP
27
28 #include "gc/g1/collectionSetChooser.hpp"
29 #include "gc/g1/g1CollectorState.hpp"
30 #include "gc/g1/g1InCSetState.hpp"
31 #include "gc/g1/g1MMUTracker.hpp"
32 #include "gc/shared/collectorPolicy.hpp"
33
34 // A G1CollectorPolicy makes policy decisions that determine the
35 // characteristics of the collector. Examples include:
36 // * choice of collection set.
37 // * when to collect.
38
39 class HeapRegion;
40 class CollectionSetChooser;
41 class G1GCPhaseTimes;
42
43 // TraceYoungGenTime collects data on _both_ young and mixed evacuation pauses
44 // (the latter may contain non-young regions - i.e. regions that are
45 // technically in old) while TraceOldGenTime collects data about full GCs.
46 class TraceYoungGenTimeData : public CHeapObj<mtGC> {
47 private:
48 unsigned _young_pause_num;
49 unsigned _mixed_pause_num;
50
51 NumberSeq _all_stop_world_times_ms;
52 NumberSeq _all_yield_times_ms;
53
54 NumberSeq _total;
55 NumberSeq _other;
56 NumberSeq _root_region_scan_wait;
57 NumberSeq _parallel;
58 NumberSeq _ext_root_scan;
59 NumberSeq _satb_filtering;
60 NumberSeq _update_rs;
61 NumberSeq _scan_rs;
62 NumberSeq _obj_copy;
63 NumberSeq _termination;
64 NumberSeq _parallel_other;
65 NumberSeq _clear_ct;
66
67 void print_summary(const char* str, const NumberSeq* seq) const;
68 void print_summary_sd(const char* str, const NumberSeq* seq) const;
69
70 public:
71 TraceYoungGenTimeData() : _young_pause_num(0), _mixed_pause_num(0) {};
72 void record_start_collection(double time_to_stop_the_world_ms);
73 void record_yield_time(double yield_time_ms);
74 void record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times);
75 void increment_young_collection_count();
76 void increment_mixed_collection_count();
77 void print() const;
78 };
79
80 class TraceOldGenTimeData : public CHeapObj<mtGC> {
81 private:
82 NumberSeq _all_full_gc_times;
83
84 public:
85 void record_full_collection(double full_gc_time_ms);
86 void print() const;
87 };
88
89 // There are three command line options related to the young gen size:
90 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
91 // just a short form for NewSize==MaxNewSize). G1 will use its internal
92 // heuristics to calculate the actual young gen size, so these options
93 // basically only limit the range within which G1 can pick a young gen
94 // size. Also, these are general options taking byte sizes. G1 will
95 // internally work with a number of regions instead. So, some rounding
96 // will occur.
97 //
98 // If nothing related to the the young gen size is set on the command
99 // line we should allow the young gen to be between G1NewSizePercent
100 // and G1MaxNewSizePercent of the heap size. This means that every time
101 // the heap size changes, the limits for the young gen size will be
102 // recalculated.
103 //
104 // If only -XX:NewSize is set we should use the specified value as the
105 // minimum size for young gen. Still using G1MaxNewSizePercent of the
106 // heap as maximum.
107 //
108 // If only -XX:MaxNewSize is set we should use the specified value as the
109 // maximum size for young gen. Still using G1NewSizePercent of the heap
110 // as minimum.
111 //
112 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
113 // No updates when the heap size changes. There is a special case when
114 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
115 // different heuristic for calculating the collection set when we do mixed
116 // collection.
117 //
118 // If only -XX:NewRatio is set we should use the specified ratio of the heap
119 // as both min and max. This will be interpreted as "fixed" just like the
120 // NewSize==MaxNewSize case above. But we will update the min and max
121 // every time the heap size changes.
122 //
123 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
124 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
125 class G1YoungGenSizer : public CHeapObj<mtGC> {
126 private:
127 enum SizerKind {
128 SizerDefaults,
129 SizerNewSizeOnly,
130 SizerMaxNewSizeOnly,
131 SizerMaxAndNewSize,
132 SizerNewRatio
133 };
134 SizerKind _sizer_kind;
135 uint _min_desired_young_length;
136 uint _max_desired_young_length;
137 bool _adaptive_size;
138 uint calculate_default_min_length(uint new_number_of_heap_regions);
139 uint calculate_default_max_length(uint new_number_of_heap_regions);
140
141 // Update the given values for minimum and maximum young gen length in regions
142 // given the number of heap regions depending on the kind of sizing algorithm.
143 void recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length);
144
145 public:
146 G1YoungGenSizer();
147 // Calculate the maximum length of the young gen given the number of regions
148 // depending on the sizing algorithm.
149 uint max_young_length(uint number_of_heap_regions);
150
151 void heap_size_changed(uint new_number_of_heap_regions);
152 uint min_desired_young_length() {
153 return _min_desired_young_length;
154 }
155 uint max_desired_young_length() {
156 return _max_desired_young_length;
157 }
158 bool adaptive_young_list_length() {
159 return _adaptive_size;
160 }
161 };
162
163 class G1CollectorPolicy: public CollectorPolicy {
164 private:
165 // either equal to the number of parallel threads, if ParallelGCThreads
166 // has been set, or 1 otherwise
167 int _parallel_gc_threads;
168
169 // The number of GC threads currently active.
170 uintx _no_of_gc_threads;
171
172 enum SomePrivateConstants {
173 NumPrevPausesForHeuristics = 10
174 };
175
176 G1MMUTracker* _mmu_tracker;
177
178 void initialize_alignments();
179 void initialize_flags();
180
181 CollectionSetChooser* _collectionSetChooser;
182
183 double _full_collection_start_sec;
184 uint _cur_collection_pause_used_regions_at_start;
185
186 // These exclude marking times.
187 TruncatedSeq* _recent_gc_times_ms;
188
189 TruncatedSeq* _concurrent_mark_remark_times_ms;
190 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
191
192 TraceYoungGenTimeData _trace_young_gen_time_data;
193 TraceOldGenTimeData _trace_old_gen_time_data;
194
195 double _stop_world_start;
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 SurvRateGroup* _short_lived_surv_rate_group;
205 SurvRateGroup* _survivor_surv_rate_group;
206 // add here any more surv rate groups
207
208 double _gc_overhead_perc;
209
210 double _reserve_factor;
211 uint _reserve_regions;
212
213 enum PredictionConstants {
214 TruncatedSeqLength = 10
215 };
216
217 TruncatedSeq* _alloc_rate_ms_seq;
218 double _prev_collection_pause_end_ms;
219
220 TruncatedSeq* _rs_length_diff_seq;
221 TruncatedSeq* _cost_per_card_ms_seq;
222 TruncatedSeq* _young_cards_per_entry_ratio_seq;
223 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
224 TruncatedSeq* _cost_per_entry_ms_seq;
225 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
226 TruncatedSeq* _cost_per_byte_ms_seq;
227 TruncatedSeq* _constant_other_time_ms_seq;
228 TruncatedSeq* _young_other_cost_per_region_ms_seq;
229 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
230
231 TruncatedSeq* _pending_cards_seq;
232 TruncatedSeq* _rs_lengths_seq;
233
234 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
235
236 G1YoungGenSizer* _young_gen_sizer;
237
238 uint _eden_cset_region_length;
239 uint _survivor_cset_region_length;
240 uint _old_cset_region_length;
241
242 void init_cset_region_lengths(uint eden_cset_region_length,
243 uint survivor_cset_region_length);
244
245 uint eden_cset_region_length() { return _eden_cset_region_length; }
246 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
247 uint old_cset_region_length() { return _old_cset_region_length; }
248
249 uint _free_regions_at_end_of_collection;
250
251 size_t _recorded_rs_lengths;
252 size_t _max_rs_lengths;
253 double _sigma;
254
255 size_t _rs_lengths_prediction;
256
257 double sigma() { return _sigma; }
258
259 // A function that prevents us putting too much stock in small sample
260 // sets. Returns a number between 2.0 and 1.0, depending on the number
261 // of samples. 5 or more samples yields one; fewer scales linearly from
262 // 2.0 at 1 sample to 1.0 at 5.
263 double confidence_factor(int samples) {
264 if (samples > 4) return 1.0;
265 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
266 }
267
268 double get_new_neg_prediction(TruncatedSeq* seq) {
269 return seq->davg() - sigma() * seq->dsd();
270 }
271
272 #ifndef PRODUCT
273 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
274 #endif // PRODUCT
275
276 void adjust_concurrent_refinement(double update_rs_time,
277 double update_rs_processed_buffers,
278 double goal_ms);
279
280 uintx no_of_gc_threads() { return _no_of_gc_threads; }
281 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
282
283 double _pause_time_target_ms;
284
285 size_t _pending_cards;
286
287 public:
288 // Accessors
289
290 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
291 hr->set_eden();
292 hr->install_surv_rate_group(_short_lived_surv_rate_group);
293 hr->set_young_index_in_cset(young_index_in_cset);
294 }
295
296 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
297 assert(hr->is_survivor(), "pre-condition");
298 hr->install_surv_rate_group(_survivor_surv_rate_group);
299 hr->set_young_index_in_cset(young_index_in_cset);
300 }
301
302 #ifndef PRODUCT
303 bool verify_young_ages();
304 #endif // PRODUCT
305
306 double get_new_prediction(TruncatedSeq* seq) {
307 return MAX2(seq->davg() + sigma() * seq->dsd(),
308 seq->davg() * confidence_factor(seq->num()));
309 }
310
311 void record_max_rs_lengths(size_t rs_lengths) {
312 _max_rs_lengths = rs_lengths;
313 }
314
315 size_t predict_rs_length_diff() {
316 return (size_t) get_new_prediction(_rs_length_diff_seq);
317 }
318
319 double predict_alloc_rate_ms() {
320 return get_new_prediction(_alloc_rate_ms_seq);
321 }
322
323 double predict_cost_per_card_ms() {
324 return get_new_prediction(_cost_per_card_ms_seq);
325 }
326
327 double predict_rs_update_time_ms(size_t pending_cards) {
328 return (double) pending_cards * predict_cost_per_card_ms();
329 }
330
331 double predict_young_cards_per_entry_ratio() {
332 return get_new_prediction(_young_cards_per_entry_ratio_seq);
333 }
334
335 double predict_mixed_cards_per_entry_ratio() {
336 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
337 return predict_young_cards_per_entry_ratio();
338 } else {
339 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
340 }
341 }
342
343 size_t predict_young_card_num(size_t rs_length) {
344 return (size_t) ((double) rs_length *
345 predict_young_cards_per_entry_ratio());
346 }
347
348 size_t predict_non_young_card_num(size_t rs_length) {
349 return (size_t) ((double) rs_length *
350 predict_mixed_cards_per_entry_ratio());
351 }
352
353 double predict_rs_scan_time_ms(size_t card_num) {
354 if (collector_state()->gcs_are_young()) {
355 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
356 } else {
357 return predict_mixed_rs_scan_time_ms(card_num);
358 }
359 }
360
361 double predict_mixed_rs_scan_time_ms(size_t card_num) {
362 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
363 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
364 } else {
365 return (double) (card_num *
366 get_new_prediction(_mixed_cost_per_entry_ms_seq));
367 }
368 }
369
370 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
371 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
372 return (1.1 * (double) bytes_to_copy) *
373 get_new_prediction(_cost_per_byte_ms_seq);
374 } else {
375 return (double) bytes_to_copy *
376 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
377 }
378 }
379
380 double predict_object_copy_time_ms(size_t bytes_to_copy) {
381 if (collector_state()->during_concurrent_mark()) {
382 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
383 } else {
384 return (double) bytes_to_copy *
385 get_new_prediction(_cost_per_byte_ms_seq);
386 }
387 }
388
389 double predict_constant_other_time_ms() {
390 return get_new_prediction(_constant_other_time_ms_seq);
391 }
392
393 double predict_young_other_time_ms(size_t young_num) {
394 return (double) young_num *
395 get_new_prediction(_young_other_cost_per_region_ms_seq);
396 }
397
398 double predict_non_young_other_time_ms(size_t non_young_num) {
399 return (double) non_young_num *
400 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
401 }
402
403 double predict_base_elapsed_time_ms(size_t pending_cards);
404 double predict_base_elapsed_time_ms(size_t pending_cards,
405 size_t scanned_cards);
406 size_t predict_bytes_to_copy(HeapRegion* hr);
407 double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc);
408
409 void set_recorded_rs_lengths(size_t rs_lengths);
410
411 uint cset_region_length() { return young_cset_region_length() +
412 old_cset_region_length(); }
413 uint young_cset_region_length() { return eden_cset_region_length() +
414 survivor_cset_region_length(); }
415
416 double predict_survivor_regions_evac_time();
417
418 void cset_regions_freed() {
419 bool propagate = collector_state()->should_propagate();
420 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
421 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
422 // also call it on any more surv rate groups
423 }
424
425 G1MMUTracker* mmu_tracker() {
426 return _mmu_tracker;
427 }
428
429 double max_pause_time_ms() {
430 return _mmu_tracker->max_gc_time() * 1000.0;
431 }
432
433 double predict_remark_time_ms() {
434 return get_new_prediction(_concurrent_mark_remark_times_ms);
435 }
436
437 double predict_cleanup_time_ms() {
438 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
439 }
440
441 // Returns an estimate of the survival rate of the region at yg-age
442 // "yg_age".
443 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
444 TruncatedSeq* seq = surv_rate_group->get_seq(age);
445 if (seq->num() == 0)
446 gclog_or_tty->print("BARF! age is %d", age);
447 guarantee( seq->num() > 0, "invariant" );
448 double pred = get_new_prediction(seq);
449 if (pred > 1.0)
450 pred = 1.0;
451 return pred;
452 }
453
454 double predict_yg_surv_rate(int age) {
455 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
456 }
457
458 double accum_yg_surv_rate_pred(int age) {
459 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
460 }
461
462 private:
463 // Statistics kept per GC stoppage, pause or full.
464 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
465
466 // Add a new GC of the given duration and end time to the record.
467 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
468
469 // The head of the list (via "next_in_collection_set()") representing the
470 // current collection set. Set from the incrementally built collection
471 // set at the start of the pause.
472 HeapRegion* _collection_set;
473
474 // The number of bytes in the collection set before the pause. Set from
475 // the incrementally built collection set at the start of an evacuation
476 // pause, and incremented in finalize_old_cset_part() when adding old regions
477 // (if any) to the collection set.
478 size_t _collection_set_bytes_used_before;
479
480 // The number of bytes copied during the GC.
481 size_t _bytes_copied_during_gc;
482
483 // The associated information that is maintained while the incremental
484 // collection set is being built with young regions. Used to populate
485 // the recorded info for the evacuation pause.
486
487 enum CSetBuildType {
488 Active, // We are actively building the collection set
489 Inactive // We are not actively building the collection set
490 };
491
492 CSetBuildType _inc_cset_build_state;
493
494 // The head of the incrementally built collection set.
495 HeapRegion* _inc_cset_head;
496
497 // The tail of the incrementally built collection set.
498 HeapRegion* _inc_cset_tail;
499
500 // The number of bytes in the incrementally built collection set.
501 // Used to set _collection_set_bytes_used_before at the start of
502 // an evacuation pause.
503 size_t _inc_cset_bytes_used_before;
504
505 // Used to record the highest end of heap region in collection set
506 HeapWord* _inc_cset_max_finger;
507
508 // The RSet lengths recorded for regions in the CSet. It is updated
509 // by the thread that adds a new region to the CSet. We assume that
510 // only one thread can be allocating a new CSet region (currently,
511 // it does so after taking the Heap_lock) hence no need to
512 // synchronize updates to this field.
513 size_t _inc_cset_recorded_rs_lengths;
514
515 // A concurrent refinement thread periodically samples the young
516 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
517 // the RSets grow. Instead of having to synchronize updates to that
518 // field we accumulate them in this field and add it to
519 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
520 ssize_t _inc_cset_recorded_rs_lengths_diffs;
521
522 // The predicted elapsed time it will take to collect the regions in
523 // the CSet. This is updated by the thread that adds a new region to
524 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
525 // MT-safety assumptions.
526 double _inc_cset_predicted_elapsed_time_ms;
527
528 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
529 double _inc_cset_predicted_elapsed_time_ms_diffs;
530
531 // Stash a pointer to the g1 heap.
532 G1CollectedHeap* _g1;
533
534 G1GCPhaseTimes* _phase_times;
535
536 // The ratio of gc time to elapsed time, computed over recent pauses.
537 double _recent_avg_pause_time_ratio;
538
539 double recent_avg_pause_time_ratio() {
540 return _recent_avg_pause_time_ratio;
541 }
542
543 // This set of variables tracks the collector efficiency, in order to
544 // determine whether we should initiate a new marking.
545 double _cur_mark_stop_world_time_ms;
546 double _mark_remark_start_sec;
547 double _mark_cleanup_start_sec;
548
549 // Update the young list target length either by setting it to the
550 // desired fixed value or by calculating it using G1's pause
551 // prediction model. If no rs_lengths parameter is passed, predict
552 // the RS lengths using the prediction model, otherwise use the
553 // given rs_lengths as the prediction.
554 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
555
556 // Calculate and return the minimum desired young list target
557 // length. This is the minimum desired young list length according
558 // to the user's inputs.
559 uint calculate_young_list_desired_min_length(uint base_min_length);
560
561 // Calculate and return the maximum desired young list target
562 // length. This is the maximum desired young list length according
563 // to the user's inputs.
564 uint calculate_young_list_desired_max_length();
565
566 // Calculate and return the maximum young list target length that
567 // can fit into the pause time goal. The parameters are: rs_lengths
568 // represent the prediction of how large the young RSet lengths will
569 // be, base_min_length is the already existing number of regions in
570 // the young list, min_length and max_length are the desired min and
571 // max young list length according to the user's inputs.
572 uint calculate_young_list_target_length(size_t rs_lengths,
573 uint base_min_length,
574 uint desired_min_length,
575 uint desired_max_length);
576
577 // Calculate and return chunk size (in number of regions) for parallel
578 // concurrent mark cleanup.
579 uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions);
580
581 // Check whether a given young length (young_length) fits into the
582 // given target pause time and whether the prediction for the amount
583 // of objects to be copied for the given length will fit into the
584 // given free space (expressed by base_free_regions). It is used by
585 // calculate_young_list_target_length().
586 bool predict_will_fit(uint young_length, double base_time_ms,
587 uint base_free_regions, double target_pause_time_ms);
588
589 // Calculate the minimum number of old regions we'll add to the CSet
590 // during a mixed GC.
591 uint calc_min_old_cset_length();
592
593 // Calculate the maximum number of old regions we'll add to the CSet
594 // during a mixed GC.
595 uint calc_max_old_cset_length();
596
597 // Returns the given amount of uncollected reclaimable space
598 // as a percentage of the current heap capacity.
599 double reclaimable_bytes_perc(size_t reclaimable_bytes);
600
601 public:
602
603 G1CollectorPolicy();
604
605 virtual G1CollectorPolicy* as_g1_policy() { return this; }
606
607 G1CollectorState* collector_state();
608
609 G1GCPhaseTimes* phase_times() const { return _phase_times; }
610
611 // Check the current value of the young list RSet lengths and
612 // compare it against the last prediction. If the current value is
613 // higher, recalculate the young list target length prediction.
614 void revise_young_list_target_length_if_necessary();
615
616 // This should be called after the heap is resized.
617 void record_new_heap_size(uint new_number_of_regions);
618
619 void init();
620
621 // Create jstat counters for the policy.
622 virtual void initialize_gc_policy_counters();
623
624 virtual HeapWord* mem_allocate_work(size_t size,
625 bool is_tlab,
626 bool* gc_overhead_limit_was_exceeded);
627
628 // This method controls how a collector handles one or more
629 // of its generations being fully allocated.
630 virtual HeapWord* satisfy_failed_allocation(size_t size,
631 bool is_tlab);
632
633 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
634
635 // Record the start and end of an evacuation pause.
636 void record_collection_pause_start(double start_time_sec);
637 void record_collection_pause_end(double pause_time_ms, size_t cards_scanned);
638
639 // Record the start and end of a full collection.
640 void record_full_collection_start();
641 void record_full_collection_end();
642
643 // Must currently be called while the world is stopped.
644 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
645
646 // Record start and end of remark.
647 void record_concurrent_mark_remark_start();
648 void record_concurrent_mark_remark_end();
649
650 // Record start, end, and completion of cleanup.
651 void record_concurrent_mark_cleanup_start();
652 void record_concurrent_mark_cleanup_end();
653 void record_concurrent_mark_cleanup_completed();
654
655 // Records the information about the heap size for reporting in
656 // print_detailed_heap_transition
657 void record_heap_size_info_at_start(bool full);
658
659 // Print heap sizing transition (with less and more detail).
660
661 void print_heap_transition(size_t bytes_before);
662 void print_heap_transition();
663 void print_detailed_heap_transition(bool full = false);
664
665 void record_stop_world_start();
666 void record_concurrent_pause();
667
668 // Record how much space we copied during a GC. This is typically
669 // called when a GC alloc region is being retired.
670 void record_bytes_copied_during_gc(size_t bytes) {
671 _bytes_copied_during_gc += bytes;
672 }
673
674 // The amount of space we copied during a GC.
675 size_t bytes_copied_during_gc() {
676 return _bytes_copied_during_gc;
677 }
678
679 size_t collection_set_bytes_used_before() const {
680 return _collection_set_bytes_used_before;
681 }
682
683 // Determine whether there are candidate regions so that the
684 // next GC should be mixed. The two action strings are used
685 // in the ergo output when the method returns true or false.
686 bool next_gc_should_be_mixed(const char* true_action_str,
687 const char* false_action_str);
688
689 // Choose a new collection set. Marks the chosen regions as being
690 // "in_collection_set", and links them together. The head and number of
691 // the collection set are available via access methods.
692 double finalize_young_cset_part(double target_pause_time_ms);
693 virtual void finalize_old_cset_part(double time_remaining_ms);
694
695 // The head of the list (via "next_in_collection_set()") representing the
696 // current collection set.
697 HeapRegion* collection_set() { return _collection_set; }
698
699 void clear_collection_set() { _collection_set = NULL; }
700
701 // Add old region "hr" to the CSet.
702 void add_old_region_to_cset(HeapRegion* hr);
703
704 // Incremental CSet Support
705
706 // The head of the incrementally built collection set.
707 HeapRegion* inc_cset_head() { return _inc_cset_head; }
708
709 // The tail of the incrementally built collection set.
710 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
711
712 // Initialize incremental collection set info.
713 void start_incremental_cset_building();
714
715 // Perform any final calculations on the incremental CSet fields
716 // before we can use them.
717 void finalize_incremental_cset_building();
718
719 void clear_incremental_cset() {
720 _inc_cset_head = NULL;
721 _inc_cset_tail = NULL;
722 }
723
724 // Stop adding regions to the incremental collection set
725 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
726
727 // Add information about hr to the aggregated information for the
728 // incrementally built collection set.
729 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
730
731 // Update information about hr in the aggregated information for
732 // the incrementally built collection set.
733 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
734
735 private:
736 // Update the incremental cset information when adding a region
737 // (should not be called directly).
738 void add_region_to_incremental_cset_common(HeapRegion* hr);
739
740 public:
741 // Add hr to the LHS of the incremental collection set.
742 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
743
744 // Add hr to the RHS of the incremental collection set.
745 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
746
747 #ifndef PRODUCT
748 void print_collection_set(HeapRegion* list_head, outputStream* st);
749 #endif // !PRODUCT
750
751 // This sets the initiate_conc_mark_if_possible() flag to start a
752 // new cycle, as long as we are not already in one. It's best if it
753 // is called during a safepoint when the test whether a cycle is in
754 // progress or not is stable.
755 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
756
757 // This is called at the very beginning of an evacuation pause (it
758 // has to be the first thing that the pause does). If
759 // initiate_conc_mark_if_possible() is true, and the concurrent
760 // marking thread has completed its work during the previous cycle,
761 // it will set during_initial_mark_pause() to so that the pause does
762 // the initial-mark work and start a marking cycle.
763 void decide_on_conc_mark_initiation();
764
765 // If an expansion would be appropriate, because recent GC overhead had
766 // exceeded the desired limit, return an amount to expand by.
767 virtual size_t expansion_amount();
768
769 // Print tracing information.
770 void print_tracing_info() const;
771
772 // Print stats on young survival ratio
773 void print_yg_surv_rate_info() const;
774
775 void finished_recalculating_age_indexes(bool is_survivors) {
776 if (is_survivors) {
777 _survivor_surv_rate_group->finished_recalculating_age_indexes();
778 } else {
779 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
780 }
781 // do that for any other surv rate groups
782 }
783
784 size_t young_list_target_length() const { return _young_list_target_length; }
785
786 bool is_young_list_full();
787
788 bool can_expand_young_list();
789
790 uint young_list_max_length() {
791 return _young_list_max_length;
792 }
793
794 bool adaptive_young_list_length() {
795 return _young_gen_sizer->adaptive_young_list_length();
796 }
797
798 private:
799 //
800 // Survivor regions policy.
801 //
802
803 // Current tenuring threshold, set to 0 if the collector reaches the
804 // maximum amount of survivors regions.
805 uint _tenuring_threshold;
806
807 // The limit on the number of regions allocated for survivors.
808 uint _max_survivor_regions;
809
810 // For reporting purposes.
811 // The value of _heap_bytes_before_gc is also used to calculate
812 // the cost of copying.
813
814 size_t _eden_used_bytes_before_gc; // Eden occupancy before GC
815 size_t _survivor_used_bytes_before_gc; // Survivor occupancy before GC
816 size_t _heap_used_bytes_before_gc; // Heap occupancy before GC
817 size_t _metaspace_used_bytes_before_gc; // Metaspace occupancy before GC
818
819 size_t _eden_capacity_bytes_before_gc; // Eden capacity before GC
820 size_t _heap_capacity_bytes_before_gc; // Heap capacity before GC
821
822 // The amount of survivor regions after a collection.
823 uint _recorded_survivor_regions;
824 // List of survivor regions.
825 HeapRegion* _recorded_survivor_head;
826 HeapRegion* _recorded_survivor_tail;
827
828 ageTable _survivors_age_table;
829
830 public:
831 uint tenuring_threshold() const { return _tenuring_threshold; }
832
833 static const uint REGIONS_UNLIMITED = (uint) -1;
834
835 uint max_regions(InCSetState dest) {
836 switch (dest.value()) {
837 case InCSetState::Young:
838 return _max_survivor_regions;
839 case InCSetState::Old:
840 return REGIONS_UNLIMITED;
841 default:
842 assert(false, err_msg("Unknown dest state: " CSETSTATE_FORMAT, dest.value()));
843 break;
844 }
845 // keep some compilers happy
846 return 0;
847 }
848
849 void note_start_adding_survivor_regions() {
850 _survivor_surv_rate_group->start_adding_regions();
851 }
852
853 void note_stop_adding_survivor_regions() {
854 _survivor_surv_rate_group->stop_adding_regions();
855 }
856
857 void record_survivor_regions(uint regions,
858 HeapRegion* head,
859 HeapRegion* tail) {
860 _recorded_survivor_regions = regions;
861 _recorded_survivor_head = head;
862 _recorded_survivor_tail = tail;
863 }
864
865 uint recorded_survivor_regions() {
866 return _recorded_survivor_regions;
867 }
868
869 void record_age_table(ageTable* age_table) {
870 _survivors_age_table.merge(age_table);
871 }
872
873 void update_max_gc_locker_expansion();
874
875 // Calculates survivor space parameters.
876 void update_survivors_policy();
877
878 virtual void post_heap_initialize();
879 };
880
881 // This should move to some place more general...
882
883 // If we have "n" measurements, and we've kept track of their "sum" and the
884 // "sum_of_squares" of the measurements, this returns the variance of the
885 // sequence.
886 inline double variance(int n, double sum_of_squares, double sum) {
887 double n_d = (double)n;
888 double avg = sum/n_d;
889 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
890 }
891
892 #endif // SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP