1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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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
40 // Yes, this is a bit unpleasant... but it saves replicating the same thing
41 // over and over again and introducing subtle problems through small typos and
42 // cutting and pasting mistakes. The macros below introduces a number
43 // sequnce into the following two classes and the methods that access it.
44
45 #define define_num_seq(name) \
46 private: \
47 NumberSeq _all_##name##_times_ms; \
48 public: \
49 void record_##name##_time_ms(double ms) { \
50 _all_##name##_times_ms.add(ms); \
51 } \
52 NumberSeq* get_##name##_seq() { \
53 return &_all_##name##_times_ms; \
54 }
55
56 class MainBodySummary;
57
58 class PauseSummary: public CHeapObj {
59 define_num_seq(total)
60 define_num_seq(other)
61
62 public:
63 virtual MainBodySummary* main_body_summary() { return NULL; }
64 };
65
66 class MainBodySummary: public CHeapObj {
67 define_num_seq(root_region_scan_wait)
68 define_num_seq(parallel) // parallel only
69 define_num_seq(ext_root_scan)
70 define_num_seq(satb_filtering)
71 define_num_seq(update_rs)
72 define_num_seq(scan_rs)
73 define_num_seq(obj_copy)
74 define_num_seq(termination) // parallel only
75 define_num_seq(parallel_other) // parallel only
76 define_num_seq(clear_ct)
77 };
78
79 class Summary: public PauseSummary,
80 public MainBodySummary {
81 public:
82 virtual MainBodySummary* main_body_summary() { return this; }
83 };
84
85 // There are three command line options related to the young gen size:
86 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
87 // just a short form for NewSize==MaxNewSize). G1 will use its internal
88 // heuristics to calculate the actual young gen size, so these options
89 // basically only limit the range within which G1 can pick a young gen
90 // size. Also, these are general options taking byte sizes. G1 will
91 // internally work with a number of regions instead. So, some rounding
92 // will occur.
93 //
94 // If nothing related to the the young gen size is set on the command
95 // line we should allow the young gen to be between
96 // G1DefaultMinNewGenPercent and G1DefaultMaxNewGenPercent of the
97 // heap size. This means that every time the heap size changes the
98 // limits for the young gen size will be updated.
99 //
100 // If only -XX:NewSize is set we should use the specified value as the
101 // minimum size for young gen. Still using G1DefaultMaxNewGenPercent
102 // of the heap as maximum.
103 //
104 // If only -XX:MaxNewSize is set we should use the specified value as the
105 // maximum size for young gen. Still using G1DefaultMinNewGenPercent
106 // of the heap as minimum.
107 //
108 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
109 // No updates when the heap size changes. There is a special case when
110 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
111 // different heuristic for calculating the collection set when we do mixed
112 // collection.
113 //
114 // If only -XX:NewRatio is set we should use the specified ratio of the heap
115 // as both min and max. This will be interpreted as "fixed" just like the
116 // NewSize==MaxNewSize case above. But we will update the min and max
117 // everytime the heap size changes.
118 //
119 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
120 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
121 class G1YoungGenSizer : public CHeapObj {
122 private:
123 enum SizerKind {
124 SizerDefaults,
125 SizerNewSizeOnly,
126 SizerMaxNewSizeOnly,
127 SizerMaxAndNewSize,
128 SizerNewRatio
129 };
130 SizerKind _sizer_kind;
131 uint _min_desired_young_length;
132 uint _max_desired_young_length;
133 bool _adaptive_size;
134 uint calculate_default_min_length(uint new_number_of_heap_regions);
135 uint calculate_default_max_length(uint new_number_of_heap_regions);
136
137 public:
138 G1YoungGenSizer();
139 void heap_size_changed(uint new_number_of_heap_regions);
140 uint min_desired_young_length() {
141 return _min_desired_young_length;
142 }
143 uint max_desired_young_length() {
144 return _max_desired_young_length;
145 }
146 bool adaptive_young_list_length() {
147 return _adaptive_size;
148 }
149 };
150
151 class G1CollectorPolicy: public CollectorPolicy {
152 private:
153 // either equal to the number of parallel threads, if ParallelGCThreads
154 // has been set, or 1 otherwise
155 int _parallel_gc_threads;
156
157 // The number of GC threads currently active.
158 uintx _no_of_gc_threads;
159
160 enum SomePrivateConstants {
161 NumPrevPausesForHeuristics = 10
162 };
163
164 G1MMUTracker* _mmu_tracker;
165
166 void initialize_flags();
167
168 void initialize_all() {
169 initialize_flags();
170 initialize_size_info();
171 initialize_perm_generation(PermGen::MarkSweepCompact);
172 }
173
174 CollectionSetChooser* _collectionSetChooser;
175
176 double _cur_collection_start_sec;
177 size_t _cur_collection_pause_used_at_start_bytes;
178 uint _cur_collection_pause_used_regions_at_start;
179 double _cur_collection_par_time_ms;
180
181 double _cur_collection_code_root_fixup_time_ms;
182
183 double _cur_clear_ct_time_ms;
184 double _cur_ref_proc_time_ms;
185 double _cur_ref_enq_time_ms;
186
187 #ifndef PRODUCT
188 // Card Table Count Cache stats
189 double _min_clear_cc_time_ms; // min
190 double _max_clear_cc_time_ms; // max
191 double _cur_clear_cc_time_ms; // clearing time during current pause
192 double _cum_clear_cc_time_ms; // cummulative clearing time
193 jlong _num_cc_clears; // number of times the card count cache has been cleared
194 #endif
195
196 // These exclude marking times.
197 TruncatedSeq* _recent_gc_times_ms;
198
199 TruncatedSeq* _concurrent_mark_remark_times_ms;
200 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
201
202 Summary* _summary;
203
204 NumberSeq* _all_pause_times_ms;
205 NumberSeq* _all_full_gc_times_ms;
206 double _stop_world_start;
207 NumberSeq* _all_stop_world_times_ms;
208 NumberSeq* _all_yield_times_ms;
209
210 int _aux_num;
211 NumberSeq* _all_aux_times_ms;
212 double* _cur_aux_start_times_ms;
213 double* _cur_aux_times_ms;
214 bool* _cur_aux_times_set;
215
216 double* _par_last_gc_worker_start_times_ms;
217 double* _par_last_ext_root_scan_times_ms;
218 double* _par_last_satb_filtering_times_ms;
219 double* _par_last_update_rs_times_ms;
220 double* _par_last_update_rs_processed_buffers;
221 double* _par_last_scan_rs_times_ms;
222 double* _par_last_obj_copy_times_ms;
223 double* _par_last_termination_times_ms;
224 double* _par_last_termination_attempts;
225 double* _par_last_gc_worker_end_times_ms;
226 double* _par_last_gc_worker_times_ms;
227
228 // Each workers 'other' time i.e. the elapsed time of the parallel
229 // code executed by a worker minus the sum of the individual sub-phase
230 // times for that worker thread.
231 double* _par_last_gc_worker_other_times_ms;
232
233 // indicates whether we are in young or mixed GC mode
234 bool _gcs_are_young;
235
236 uint _young_list_target_length;
237 uint _young_list_fixed_length;
238 size_t _prev_eden_capacity; // used for logging
239
240 // The max number of regions we can extend the eden by while the GC
241 // locker is active. This should be >= _young_list_target_length;
242 uint _young_list_max_length;
243
244 bool _last_gc_was_young;
245
246 unsigned _young_pause_num;
247 unsigned _mixed_pause_num;
248
249 bool _during_marking;
250 bool _in_marking_window;
251 bool _in_marking_window_im;
252
253 SurvRateGroup* _short_lived_surv_rate_group;
254 SurvRateGroup* _survivor_surv_rate_group;
255 // add here any more surv rate groups
256
257 double _gc_overhead_perc;
258
259 double _reserve_factor;
260 uint _reserve_regions;
261
262 bool during_marking() {
263 return _during_marking;
264 }
265
266 private:
267 enum PredictionConstants {
268 TruncatedSeqLength = 10
269 };
270
271 TruncatedSeq* _alloc_rate_ms_seq;
272 double _prev_collection_pause_end_ms;
273
274 TruncatedSeq* _pending_card_diff_seq;
275 TruncatedSeq* _rs_length_diff_seq;
276 TruncatedSeq* _cost_per_card_ms_seq;
277 TruncatedSeq* _young_cards_per_entry_ratio_seq;
278 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
279 TruncatedSeq* _cost_per_entry_ms_seq;
280 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
281 TruncatedSeq* _cost_per_byte_ms_seq;
282 TruncatedSeq* _constant_other_time_ms_seq;
283 TruncatedSeq* _young_other_cost_per_region_ms_seq;
284 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
285
286 TruncatedSeq* _pending_cards_seq;
287 TruncatedSeq* _rs_lengths_seq;
288
289 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
290
291 G1YoungGenSizer* _young_gen_sizer;
292
293 uint _eden_cset_region_length;
294 uint _survivor_cset_region_length;
295 uint _old_cset_region_length;
296
297 void init_cset_region_lengths(uint eden_cset_region_length,
298 uint survivor_cset_region_length);
299
300 uint eden_cset_region_length() { return _eden_cset_region_length; }
301 uint survivor_cset_region_length() { return _survivor_cset_region_length; }
302 uint old_cset_region_length() { return _old_cset_region_length; }
303
304 uint _free_regions_at_end_of_collection;
305
306 size_t _recorded_rs_lengths;
307 size_t _max_rs_lengths;
308
309 double _recorded_young_free_cset_time_ms;
310 double _recorded_non_young_free_cset_time_ms;
311
312 double _sigma;
313
314 size_t _rs_lengths_prediction;
315
316 double sigma() { return _sigma; }
317
318 // A function that prevents us putting too much stock in small sample
319 // sets. Returns a number between 2.0 and 1.0, depending on the number
320 // of samples. 5 or more samples yields one; fewer scales linearly from
321 // 2.0 at 1 sample to 1.0 at 5.
322 double confidence_factor(int samples) {
323 if (samples > 4) return 1.0;
324 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
325 }
326
327 double get_new_neg_prediction(TruncatedSeq* seq) {
328 return seq->davg() - sigma() * seq->dsd();
329 }
330
331 #ifndef PRODUCT
332 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
333 #endif // PRODUCT
334
335 void adjust_concurrent_refinement(double update_rs_time,
336 double update_rs_processed_buffers,
337 double goal_ms);
338
339 uintx no_of_gc_threads() { return _no_of_gc_threads; }
340 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
341
342 double _pause_time_target_ms;
343 double _recorded_young_cset_choice_time_ms;
344 double _recorded_non_young_cset_choice_time_ms;
345 size_t _pending_cards;
346 size_t _max_pending_cards;
347
348 public:
349 // Accessors
350
351 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
352 hr->set_young();
353 hr->install_surv_rate_group(_short_lived_surv_rate_group);
354 hr->set_young_index_in_cset(young_index_in_cset);
355 }
356
357 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
358 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
359 hr->install_surv_rate_group(_survivor_surv_rate_group);
360 hr->set_young_index_in_cset(young_index_in_cset);
361 }
362
363 #ifndef PRODUCT
364 bool verify_young_ages();
365 #endif // PRODUCT
366
367 double get_new_prediction(TruncatedSeq* seq) {
368 return MAX2(seq->davg() + sigma() * seq->dsd(),
369 seq->davg() * confidence_factor(seq->num()));
370 }
371
372 void record_max_rs_lengths(size_t rs_lengths) {
373 _max_rs_lengths = rs_lengths;
374 }
375
376 size_t predict_pending_card_diff() {
377 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
378 if (prediction < 0.00001) {
379 return 0;
380 } else {
381 return (size_t) prediction;
382 }
383 }
384
385 size_t predict_pending_cards() {
386 size_t max_pending_card_num = _g1->max_pending_card_num();
387 size_t diff = predict_pending_card_diff();
388 size_t prediction;
389 if (diff > max_pending_card_num) {
390 prediction = max_pending_card_num;
391 } else {
392 prediction = max_pending_card_num - diff;
393 }
394
395 return prediction;
396 }
397
398 size_t predict_rs_length_diff() {
399 return (size_t) get_new_prediction(_rs_length_diff_seq);
400 }
401
402 double predict_alloc_rate_ms() {
403 return get_new_prediction(_alloc_rate_ms_seq);
404 }
405
406 double predict_cost_per_card_ms() {
407 return get_new_prediction(_cost_per_card_ms_seq);
408 }
409
410 double predict_rs_update_time_ms(size_t pending_cards) {
411 return (double) pending_cards * predict_cost_per_card_ms();
412 }
413
414 double predict_young_cards_per_entry_ratio() {
415 return get_new_prediction(_young_cards_per_entry_ratio_seq);
416 }
417
418 double predict_mixed_cards_per_entry_ratio() {
419 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
420 return predict_young_cards_per_entry_ratio();
421 } else {
422 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
423 }
424 }
425
426 size_t predict_young_card_num(size_t rs_length) {
427 return (size_t) ((double) rs_length *
428 predict_young_cards_per_entry_ratio());
429 }
430
431 size_t predict_non_young_card_num(size_t rs_length) {
432 return (size_t) ((double) rs_length *
433 predict_mixed_cards_per_entry_ratio());
434 }
435
436 double predict_rs_scan_time_ms(size_t card_num) {
437 if (gcs_are_young()) {
438 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
439 } else {
440 return predict_mixed_rs_scan_time_ms(card_num);
441 }
442 }
443
444 double predict_mixed_rs_scan_time_ms(size_t card_num) {
445 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
446 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
447 } else {
448 return (double) (card_num *
449 get_new_prediction(_mixed_cost_per_entry_ms_seq));
450 }
451 }
452
453 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
454 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
455 return (1.1 * (double) bytes_to_copy) *
456 get_new_prediction(_cost_per_byte_ms_seq);
457 } else {
458 return (double) bytes_to_copy *
459 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
460 }
461 }
462
463 double predict_object_copy_time_ms(size_t bytes_to_copy) {
464 if (_in_marking_window && !_in_marking_window_im) {
465 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
466 } else {
467 return (double) bytes_to_copy *
468 get_new_prediction(_cost_per_byte_ms_seq);
469 }
470 }
471
472 double predict_constant_other_time_ms() {
473 return get_new_prediction(_constant_other_time_ms_seq);
474 }
475
476 double predict_young_other_time_ms(size_t young_num) {
477 return (double) young_num *
478 get_new_prediction(_young_other_cost_per_region_ms_seq);
479 }
480
481 double predict_non_young_other_time_ms(size_t non_young_num) {
482 return (double) non_young_num *
483 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
484 }
485
486 double predict_base_elapsed_time_ms(size_t pending_cards);
487 double predict_base_elapsed_time_ms(size_t pending_cards,
488 size_t scanned_cards);
489 size_t predict_bytes_to_copy(HeapRegion* hr);
490 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
491
492 void set_recorded_rs_lengths(size_t rs_lengths);
493
494 uint cset_region_length() { return young_cset_region_length() +
495 old_cset_region_length(); }
496 uint young_cset_region_length() { return eden_cset_region_length() +
497 survivor_cset_region_length(); }
498
499 void record_young_free_cset_time_ms(double time_ms) {
500 _recorded_young_free_cset_time_ms = time_ms;
501 }
502
503 void record_non_young_free_cset_time_ms(double time_ms) {
504 _recorded_non_young_free_cset_time_ms = time_ms;
505 }
506
507 double predict_survivor_regions_evac_time();
508
509 void cset_regions_freed() {
510 bool propagate = _last_gc_was_young && !_in_marking_window;
511 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
512 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
513 // also call it on any more surv rate groups
514 }
515
516 G1MMUTracker* mmu_tracker() {
517 return _mmu_tracker;
518 }
519
520 double max_pause_time_ms() {
521 return _mmu_tracker->max_gc_time() * 1000.0;
522 }
523
524 double predict_remark_time_ms() {
525 return get_new_prediction(_concurrent_mark_remark_times_ms);
526 }
527
528 double predict_cleanup_time_ms() {
529 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
530 }
531
532 // Returns an estimate of the survival rate of the region at yg-age
533 // "yg_age".
534 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
535 TruncatedSeq* seq = surv_rate_group->get_seq(age);
536 if (seq->num() == 0)
537 gclog_or_tty->print("BARF! age is %d", age);
538 guarantee( seq->num() > 0, "invariant" );
539 double pred = get_new_prediction(seq);
540 if (pred > 1.0)
541 pred = 1.0;
542 return pred;
543 }
544
545 double predict_yg_surv_rate(int age) {
546 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
547 }
548
549 double accum_yg_surv_rate_pred(int age) {
550 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
551 }
552
553 private:
554 void print_stats(int level, const char* str, double value);
555 void print_stats(int level, const char* str, double value, int workers);
556 void print_stats(int level, const char* str, int value);
557
558 void print_par_stats(int level, const char* str, double* data, bool showDecimals = true);
559
560 void check_other_times(int level,
561 NumberSeq* other_times_ms,
562 NumberSeq* calc_other_times_ms) const;
563
564 void print_summary (PauseSummary* stats) const;
565
566 void print_summary (int level, const char* str, NumberSeq* seq) const;
567 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
568
569 double avg_value (double* data);
570 double max_value (double* data);
571 double sum_of_values (double* data);
572 double max_sum (double* data1, double* data2);
573
574 double _last_pause_time_ms;
575
576 size_t _bytes_in_collection_set_before_gc;
577 size_t _bytes_copied_during_gc;
578
579 // Used to count used bytes in CS.
580 friend class CountCSClosure;
581
582 // Statistics kept per GC stoppage, pause or full.
583 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
584
585 // Add a new GC of the given duration and end time to the record.
586 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
587
588 // The head of the list (via "next_in_collection_set()") representing the
589 // current collection set. Set from the incrementally built collection
590 // set at the start of the pause.
591 HeapRegion* _collection_set;
592
593 // The number of bytes in the collection set before the pause. Set from
594 // the incrementally built collection set at the start of an evacuation
595 // pause.
596 size_t _collection_set_bytes_used_before;
597
598 // The associated information that is maintained while the incremental
599 // collection set is being built with young regions. Used to populate
600 // the recorded info for the evacuation pause.
601
602 enum CSetBuildType {
603 Active, // We are actively building the collection set
604 Inactive // We are not actively building the collection set
605 };
606
607 CSetBuildType _inc_cset_build_state;
608
609 // The head of the incrementally built collection set.
610 HeapRegion* _inc_cset_head;
611
612 // The tail of the incrementally built collection set.
613 HeapRegion* _inc_cset_tail;
614
615 // The number of bytes in the incrementally built collection set.
616 // Used to set _collection_set_bytes_used_before at the start of
617 // an evacuation pause.
618 size_t _inc_cset_bytes_used_before;
619
620 // Used to record the highest end of heap region in collection set
621 HeapWord* _inc_cset_max_finger;
622
623 // The RSet lengths recorded for regions in the CSet. It is updated
624 // by the thread that adds a new region to the CSet. We assume that
625 // only one thread can be allocating a new CSet region (currently,
626 // it does so after taking the Heap_lock) hence no need to
627 // synchronize updates to this field.
628 size_t _inc_cset_recorded_rs_lengths;
629
630 // A concurrent refinement thread periodcially samples the young
631 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
632 // the RSets grow. Instead of having to syncronize updates to that
633 // field we accumulate them in this field and add it to
634 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
635 ssize_t _inc_cset_recorded_rs_lengths_diffs;
636
637 // The predicted elapsed time it will take to collect the regions in
638 // the CSet. This is updated by the thread that adds a new region to
639 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
640 // MT-safety assumptions.
641 double _inc_cset_predicted_elapsed_time_ms;
642
643 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
644 double _inc_cset_predicted_elapsed_time_ms_diffs;
645
646 // Stash a pointer to the g1 heap.
647 G1CollectedHeap* _g1;
648
649 // The ratio of gc time to elapsed time, computed over recent pauses.
650 double _recent_avg_pause_time_ratio;
651
652 double recent_avg_pause_time_ratio() {
653 return _recent_avg_pause_time_ratio;
654 }
655
656 // At the end of a pause we check the heap occupancy and we decide
657 // whether we will start a marking cycle during the next pause. If
658 // we decide that we want to do that, we will set this parameter to
659 // true. So, this parameter will stay true between the end of a
660 // pause and the beginning of a subsequent pause (not necessarily
661 // the next one, see the comments on the next field) when we decide
662 // that we will indeed start a marking cycle and do the initial-mark
663 // work.
664 volatile bool _initiate_conc_mark_if_possible;
665
666 // If initiate_conc_mark_if_possible() is set at the beginning of a
667 // pause, it is a suggestion that the pause should start a marking
668 // cycle by doing the initial-mark work. However, it is possible
669 // that the concurrent marking thread is still finishing up the
670 // previous marking cycle (e.g., clearing the next marking
671 // bitmap). If that is the case we cannot start a new cycle and
672 // we'll have to wait for the concurrent marking thread to finish
673 // what it is doing. In this case we will postpone the marking cycle
674 // initiation decision for the next pause. When we eventually decide
675 // to start a cycle, we will set _during_initial_mark_pause which
676 // will stay true until the end of the initial-mark pause and it's
677 // the condition that indicates that a pause is doing the
678 // initial-mark work.
679 volatile bool _during_initial_mark_pause;
680
681 bool _last_young_gc;
682
683 // This set of variables tracks the collector efficiency, in order to
684 // determine whether we should initiate a new marking.
685 double _cur_mark_stop_world_time_ms;
686 double _mark_remark_start_sec;
687 double _mark_cleanup_start_sec;
688 double _root_region_scan_wait_time_ms;
689
690 // Update the young list target length either by setting it to the
691 // desired fixed value or by calculating it using G1's pause
692 // prediction model. If no rs_lengths parameter is passed, predict
693 // the RS lengths using the prediction model, otherwise use the
694 // given rs_lengths as the prediction.
695 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
696
697 // Calculate and return the minimum desired young list target
698 // length. This is the minimum desired young list length according
699 // to the user's inputs.
700 uint calculate_young_list_desired_min_length(uint base_min_length);
701
702 // Calculate and return the maximum desired young list target
703 // length. This is the maximum desired young list length according
704 // to the user's inputs.
705 uint calculate_young_list_desired_max_length();
706
707 // Calculate and return the maximum young list target length that
708 // can fit into the pause time goal. The parameters are: rs_lengths
709 // represent the prediction of how large the young RSet lengths will
710 // be, base_min_length is the alreay existing number of regions in
711 // the young list, min_length and max_length are the desired min and
712 // max young list length according to the user's inputs.
713 uint calculate_young_list_target_length(size_t rs_lengths,
714 uint base_min_length,
715 uint desired_min_length,
716 uint desired_max_length);
717
718 // Check whether a given young length (young_length) fits into the
719 // given target pause time and whether the prediction for the amount
720 // of objects to be copied for the given length will fit into the
721 // given free space (expressed by base_free_regions). It is used by
722 // calculate_young_list_target_length().
723 bool predict_will_fit(uint young_length, double base_time_ms,
724 uint base_free_regions, double target_pause_time_ms);
725
726 // Count the number of bytes used in the CS.
727 void count_CS_bytes_used();
728
729 public:
730
731 G1CollectorPolicy();
732
733 virtual G1CollectorPolicy* as_g1_policy() { return this; }
734
735 virtual CollectorPolicy::Name kind() {
736 return CollectorPolicy::G1CollectorPolicyKind;
737 }
738
739 // Check the current value of the young list RSet lengths and
740 // compare it against the last prediction. If the current value is
741 // higher, recalculate the young list target length prediction.
742 void revise_young_list_target_length_if_necessary();
743
744 size_t bytes_in_collection_set() {
745 return _bytes_in_collection_set_before_gc;
746 }
747
748 unsigned calc_gc_alloc_time_stamp() {
749 return _all_pause_times_ms->num() + 1;
750 }
751
752 // This should be called after the heap is resized.
753 void record_new_heap_size(uint new_number_of_regions);
754
755 void init();
756
757 // Create jstat counters for the policy.
758 virtual void initialize_gc_policy_counters();
759
760 virtual HeapWord* mem_allocate_work(size_t size,
761 bool is_tlab,
762 bool* gc_overhead_limit_was_exceeded);
763
764 // This method controls how a collector handles one or more
765 // of its generations being fully allocated.
766 virtual HeapWord* satisfy_failed_allocation(size_t size,
767 bool is_tlab);
768
769 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
770
771 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
772
773 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
774
775 // Update the heuristic info to record a collection pause of the given
776 // start time, where the given number of bytes were used at the start.
777 // This may involve changing the desired size of a collection set.
778
779 void record_stop_world_start();
780
781 void record_collection_pause_start(double start_time_sec, size_t start_used);
782
783 // Must currently be called while the world is stopped.
784 void record_concurrent_mark_init_end(double
785 mark_init_elapsed_time_ms);
786
787 void record_root_region_scan_wait_time(double time_ms) {
788 _root_region_scan_wait_time_ms = time_ms;
789 }
790
791 void record_concurrent_mark_remark_start();
792 void record_concurrent_mark_remark_end();
793
794 void record_concurrent_mark_cleanup_start();
795 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
796 void record_concurrent_mark_cleanup_completed();
797
798 void record_concurrent_pause();
799 void record_concurrent_pause_end();
800
801 void record_collection_pause_end(int no_of_gc_threads);
802 void print_heap_transition();
803
804 // Record the fact that a full collection occurred.
805 void record_full_collection_start();
806 void record_full_collection_end();
807
808 void record_gc_worker_start_time(int worker_i, double ms) {
809 _par_last_gc_worker_start_times_ms[worker_i] = ms;
810 }
811
812 void record_ext_root_scan_time(int worker_i, double ms) {
813 _par_last_ext_root_scan_times_ms[worker_i] = ms;
814 }
815
816 void record_satb_filtering_time(int worker_i, double ms) {
817 _par_last_satb_filtering_times_ms[worker_i] = ms;
818 }
819
820 void record_update_rs_time(int thread, double ms) {
821 _par_last_update_rs_times_ms[thread] = ms;
822 }
823
824 void record_update_rs_processed_buffers (int thread,
825 double processed_buffers) {
826 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
827 }
828
829 void record_scan_rs_time(int thread, double ms) {
830 _par_last_scan_rs_times_ms[thread] = ms;
831 }
832
833 void reset_obj_copy_time(int thread) {
834 _par_last_obj_copy_times_ms[thread] = 0.0;
835 }
836
837 void reset_obj_copy_time() {
838 reset_obj_copy_time(0);
839 }
840
841 void record_obj_copy_time(int thread, double ms) {
842 _par_last_obj_copy_times_ms[thread] += ms;
843 }
844
845 void record_termination(int thread, double ms, size_t attempts) {
846 _par_last_termination_times_ms[thread] = ms;
847 _par_last_termination_attempts[thread] = (double) attempts;
848 }
849
850 void record_gc_worker_end_time(int worker_i, double ms) {
851 _par_last_gc_worker_end_times_ms[worker_i] = ms;
852 }
853
854 void record_pause_time_ms(double ms) {
855 _last_pause_time_ms = ms;
856 }
857
858 void record_clear_ct_time(double ms) {
859 _cur_clear_ct_time_ms = ms;
860 }
861
862 void record_par_time(double ms) {
863 _cur_collection_par_time_ms = ms;
864 }
865
866 void record_code_root_fixup_time(double ms) {
867 _cur_collection_code_root_fixup_time_ms = ms;
868 }
869
870 void record_aux_start_time(int i) {
871 guarantee(i < _aux_num, "should be within range");
872 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
873 }
874
875 void record_aux_end_time(int i) {
876 guarantee(i < _aux_num, "should be within range");
877 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
878 _cur_aux_times_set[i] = true;
879 _cur_aux_times_ms[i] += ms;
880 }
881
882 void record_ref_proc_time(double ms) {
883 _cur_ref_proc_time_ms = ms;
884 }
885
886 void record_ref_enq_time(double ms) {
887 _cur_ref_enq_time_ms = ms;
888 }
889
890 #ifndef PRODUCT
891 void record_cc_clear_time(double ms) {
892 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
893 _min_clear_cc_time_ms = ms;
894 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
895 _max_clear_cc_time_ms = ms;
896 _cur_clear_cc_time_ms = ms;
897 _cum_clear_cc_time_ms += ms;
898 _num_cc_clears++;
899 }
900 #endif
901
902 // Record how much space we copied during a GC. This is typically
903 // called when a GC alloc region is being retired.
904 void record_bytes_copied_during_gc(size_t bytes) {
905 _bytes_copied_during_gc += bytes;
906 }
907
908 // The amount of space we copied during a GC.
909 size_t bytes_copied_during_gc() {
910 return _bytes_copied_during_gc;
911 }
912
913 // Determine whether there are candidate regions so that the
914 // next GC should be mixed. The two action strings are used
915 // in the ergo output when the method returns true or false.
916 bool next_gc_should_be_mixed(const char* true_action_str,
917 const char* false_action_str);
918
919 // Choose a new collection set. Marks the chosen regions as being
920 // "in_collection_set", and links them together. The head and number of
921 // the collection set are available via access methods.
922 void finalize_cset(double target_pause_time_ms);
923
924 // The head of the list (via "next_in_collection_set()") representing the
925 // current collection set.
926 HeapRegion* collection_set() { return _collection_set; }
927
928 void clear_collection_set() { _collection_set = NULL; }
929
930 // Add old region "hr" to the CSet.
931 void add_old_region_to_cset(HeapRegion* hr);
932
933 // Incremental CSet Support
934
935 // The head of the incrementally built collection set.
936 HeapRegion* inc_cset_head() { return _inc_cset_head; }
937
938 // The tail of the incrementally built collection set.
939 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
940
941 // Initialize incremental collection set info.
942 void start_incremental_cset_building();
943
944 // Perform any final calculations on the incremental CSet fields
945 // before we can use them.
946 void finalize_incremental_cset_building();
947
948 void clear_incremental_cset() {
949 _inc_cset_head = NULL;
950 _inc_cset_tail = NULL;
951 }
952
953 // Stop adding regions to the incremental collection set
954 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
955
956 // Add information about hr to the aggregated information for the
957 // incrementally built collection set.
958 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
959
960 // Update information about hr in the aggregated information for
961 // the incrementally built collection set.
962 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
963
964 private:
965 // Update the incremental cset information when adding a region
966 // (should not be called directly).
967 void add_region_to_incremental_cset_common(HeapRegion* hr);
968
969 public:
970 // Add hr to the LHS of the incremental collection set.
971 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
972
973 // Add hr to the RHS of the incremental collection set.
974 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
975
976 #ifndef PRODUCT
977 void print_collection_set(HeapRegion* list_head, outputStream* st);
978 #endif // !PRODUCT
979
980 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
981 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
982 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
983
984 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
985 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
986 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
987
988 // This sets the initiate_conc_mark_if_possible() flag to start a
989 // new cycle, as long as we are not already in one. It's best if it
990 // is called during a safepoint when the test whether a cycle is in
991 // progress or not is stable.
992 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
993
994 // This is called at the very beginning of an evacuation pause (it
995 // has to be the first thing that the pause does). If
996 // initiate_conc_mark_if_possible() is true, and the concurrent
997 // marking thread has completed its work during the previous cycle,
998 // it will set during_initial_mark_pause() to so that the pause does
999 // the initial-mark work and start a marking cycle.
1000 void decide_on_conc_mark_initiation();
1001
1002 // If an expansion would be appropriate, because recent GC overhead had
1003 // exceeded the desired limit, return an amount to expand by.
1004 size_t expansion_amount();
1005
1006 // Print tracing information.
1007 void print_tracing_info() const;
1008
1009 // Print stats on young survival ratio
1010 void print_yg_surv_rate_info() const;
1011
1012 void finished_recalculating_age_indexes(bool is_survivors) {
1013 if (is_survivors) {
1014 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1015 } else {
1016 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1017 }
1018 // do that for any other surv rate groups
1019 }
1020
1021 bool is_young_list_full() {
1022 uint young_list_length = _g1->young_list()->length();
1023 uint young_list_target_length = _young_list_target_length;
1024 return young_list_length >= young_list_target_length;
1025 }
1026
1027 bool can_expand_young_list() {
1028 uint young_list_length = _g1->young_list()->length();
1029 uint young_list_max_length = _young_list_max_length;
1030 return young_list_length < young_list_max_length;
1031 }
1032
1033 uint young_list_max_length() {
1034 return _young_list_max_length;
1035 }
1036
1037 bool gcs_are_young() {
1038 return _gcs_are_young;
1039 }
1040 void set_gcs_are_young(bool gcs_are_young) {
1041 _gcs_are_young = gcs_are_young;
1042 }
1043
1044 bool adaptive_young_list_length() {
1045 return _young_gen_sizer->adaptive_young_list_length();
1046 }
1047
1048 private:
1049 //
1050 // Survivor regions policy.
1051 //
1052
1053 // Current tenuring threshold, set to 0 if the collector reaches the
1054 // maximum amount of suvivors regions.
1055 int _tenuring_threshold;
1056
1057 // The limit on the number of regions allocated for survivors.
1058 uint _max_survivor_regions;
1059
1060 // For reporting purposes.
1061 size_t _eden_bytes_before_gc;
1062 size_t _survivor_bytes_before_gc;
1063 size_t _capacity_before_gc;
1064
1065 // The amount of survor regions after a collection.
1066 uint _recorded_survivor_regions;
1067 // List of survivor regions.
1068 HeapRegion* _recorded_survivor_head;
1069 HeapRegion* _recorded_survivor_tail;
1070
1071 ageTable _survivors_age_table;
1072
1073 public:
1074
1075 inline GCAllocPurpose
1076 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1077 if (age < _tenuring_threshold && src_region->is_young()) {
1078 return GCAllocForSurvived;
1079 } else {
1080 return GCAllocForTenured;
1081 }
1082 }
1083
1084 inline bool track_object_age(GCAllocPurpose purpose) {
1085 return purpose == GCAllocForSurvived;
1086 }
1087
1088 static const uint REGIONS_UNLIMITED = (uint) -1;
1089
1090 uint max_regions(int purpose);
1091
1092 // The limit on regions for a particular purpose is reached.
1093 void note_alloc_region_limit_reached(int purpose) {
1094 if (purpose == GCAllocForSurvived) {
1095 _tenuring_threshold = 0;
1096 }
1097 }
1098
1099 void note_start_adding_survivor_regions() {
1100 _survivor_surv_rate_group->start_adding_regions();
1101 }
1102
1103 void note_stop_adding_survivor_regions() {
1104 _survivor_surv_rate_group->stop_adding_regions();
1105 }
1106
1107 void record_survivor_regions(uint regions,
1108 HeapRegion* head,
1109 HeapRegion* tail) {
1110 _recorded_survivor_regions = regions;
1111 _recorded_survivor_head = head;
1112 _recorded_survivor_tail = tail;
1113 }
1114
1115 uint recorded_survivor_regions() {
1116 return _recorded_survivor_regions;
1117 }
1118
1119 void record_thread_age_table(ageTable* age_table) {
1120 _survivors_age_table.merge_par(age_table);
1121 }
1122
1123 void update_max_gc_locker_expansion();
1124
1125 // Calculates survivor space parameters.
1126 void update_survivors_policy();
1127
1128 };
1129
1130 // This should move to some place more general...
1131
1132 // If we have "n" measurements, and we've kept track of their "sum" and the
1133 // "sum_of_squares" of the measurements, this returns the variance of the
1134 // sequence.
1135 inline double variance(int n, double sum_of_squares, double sum) {
1136 double n_d = (double)n;
1137 double avg = sum/n_d;
1138 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1139 }
1140
1141 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP