1 /*
2 * Copyright (c) 2001, 2011, 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.
22 *
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(satb_drain) // optional
68 define_num_seq(parallel) // parallel only
69 define_num_seq(ext_root_scan)
70 define_num_seq(mark_stack_scan)
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(mark_closure)
77 define_num_seq(clear_ct)
78 };
79
80 class Summary: public PauseSummary,
81 public MainBodySummary {
82 public:
83 virtual MainBodySummary* main_body_summary() { return this; }
84 };
85
86 class G1CollectorPolicy: public CollectorPolicy {
87 private:
88 // either equal to the number of parallel threads, if ParallelGCThreads
89 // has been set, or 1 otherwise
90 int _parallel_gc_threads;
91
92 // The number of GC threads currently active.
93 uintx _no_of_gc_threads;
94
95 enum SomePrivateConstants {
96 NumPrevPausesForHeuristics = 10
97 };
98
99 G1MMUTracker* _mmu_tracker;
100
101 void initialize_flags();
102
103 void initialize_all() {
104 initialize_flags();
105 initialize_size_info();
106 initialize_perm_generation(PermGen::MarkSweepCompact);
107 }
108
109 CollectionSetChooser* _collectionSetChooser;
110
111 double _cur_collection_start_sec;
112 size_t _cur_collection_pause_used_at_start_bytes;
113 size_t _cur_collection_pause_used_regions_at_start;
114 size_t _prev_collection_pause_used_at_end_bytes;
115 double _cur_collection_par_time_ms;
116 double _cur_satb_drain_time_ms;
117 double _cur_clear_ct_time_ms;
118 double _cur_ref_proc_time_ms;
119 double _cur_ref_enq_time_ms;
120
121 #ifndef PRODUCT
122 // Card Table Count Cache stats
123 double _min_clear_cc_time_ms; // min
124 double _max_clear_cc_time_ms; // max
125 double _cur_clear_cc_time_ms; // clearing time during current pause
126 double _cum_clear_cc_time_ms; // cummulative clearing time
127 jlong _num_cc_clears; // number of times the card count cache has been cleared
128 #endif
129
130 // These exclude marking times.
131 TruncatedSeq* _recent_gc_times_ms;
132
133 TruncatedSeq* _concurrent_mark_remark_times_ms;
134 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
135
136 Summary* _summary;
137
138 NumberSeq* _all_pause_times_ms;
139 NumberSeq* _all_full_gc_times_ms;
140 double _stop_world_start;
141 NumberSeq* _all_stop_world_times_ms;
142 NumberSeq* _all_yield_times_ms;
143
144 int _aux_num;
145 NumberSeq* _all_aux_times_ms;
146 double* _cur_aux_start_times_ms;
147 double* _cur_aux_times_ms;
148 bool* _cur_aux_times_set;
149
150 double* _par_last_gc_worker_start_times_ms;
151 double* _par_last_ext_root_scan_times_ms;
152 double* _par_last_mark_stack_scan_times_ms;
153 double* _par_last_update_rs_times_ms;
154 double* _par_last_update_rs_processed_buffers;
155 double* _par_last_scan_rs_times_ms;
156 double* _par_last_obj_copy_times_ms;
157 double* _par_last_termination_times_ms;
158 double* _par_last_termination_attempts;
159 double* _par_last_gc_worker_end_times_ms;
160 double* _par_last_gc_worker_times_ms;
161
162 // Each workers 'other' time i.e. the elapsed time of the parallel
163 // phase of the pause minus the sum of the individual sub-phase
164 // times for a given worker thread.
165 double* _par_last_gc_worker_other_times_ms;
166
167 // indicates whether we are in young or mixed GC mode
168 bool _gcs_are_young;
169
170 // if true, then it tries to dynamically adjust the length of the
171 // young list
172 bool _adaptive_young_list_length;
173 size_t _young_list_target_length;
174 size_t _young_list_fixed_length;
175 size_t _prev_eden_capacity; // used for logging
176
177 // The max number of regions we can extend the eden by while the GC
178 // locker is active. This should be >= _young_list_target_length;
179 size_t _young_list_max_length;
180
181 bool _last_gc_was_young;
182
183 unsigned _young_pause_num;
184 unsigned _mixed_pause_num;
185
186 bool _during_marking;
187 bool _in_marking_window;
188 bool _in_marking_window_im;
189
190 SurvRateGroup* _short_lived_surv_rate_group;
191 SurvRateGroup* _survivor_surv_rate_group;
192 // add here any more surv rate groups
193
194 double _gc_overhead_perc;
195
196 double _reserve_factor;
197 size_t _reserve_regions;
198
199 bool during_marking() {
200 return _during_marking;
201 }
202
203 private:
204 enum PredictionConstants {
205 TruncatedSeqLength = 10
206 };
207
208 TruncatedSeq* _alloc_rate_ms_seq;
209 double _prev_collection_pause_end_ms;
210
211 TruncatedSeq* _pending_card_diff_seq;
212 TruncatedSeq* _rs_length_diff_seq;
213 TruncatedSeq* _cost_per_card_ms_seq;
214 TruncatedSeq* _young_cards_per_entry_ratio_seq;
215 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
216 TruncatedSeq* _cost_per_entry_ms_seq;
217 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
218 TruncatedSeq* _cost_per_byte_ms_seq;
219 TruncatedSeq* _constant_other_time_ms_seq;
220 TruncatedSeq* _young_other_cost_per_region_ms_seq;
221 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
222
223 TruncatedSeq* _pending_cards_seq;
224 TruncatedSeq* _rs_lengths_seq;
225
226 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
227
228 TruncatedSeq* _young_gc_eff_seq;
229
230 bool _using_new_ratio_calculations;
231 size_t _min_desired_young_length; // as set on the command line or default calculations
232 size_t _max_desired_young_length; // as set on the command line or default calculations
233
234 size_t _eden_cset_region_length;
235 size_t _survivor_cset_region_length;
236 size_t _old_cset_region_length;
237
238 void init_cset_region_lengths(size_t eden_cset_region_length,
239 size_t survivor_cset_region_length);
240
241 size_t eden_cset_region_length() { return _eden_cset_region_length; }
242 size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
243 size_t old_cset_region_length() { return _old_cset_region_length; }
244
245 size_t _free_regions_at_end_of_collection;
246
247 size_t _recorded_rs_lengths;
248 size_t _max_rs_lengths;
249
250 double _recorded_young_free_cset_time_ms;
251 double _recorded_non_young_free_cset_time_ms;
252
253 double _sigma;
254 double _expensive_region_limit_ms;
255
256 size_t _rs_lengths_prediction;
257
258 size_t _known_garbage_bytes;
259 double _known_garbage_ratio;
260
261 double sigma() {
262 return _sigma;
263 }
264
265 // A function that prevents us putting too much stock in small sample
266 // sets. Returns a number between 2.0 and 1.0, depending on the number
267 // of samples. 5 or more samples yields one; fewer scales linearly from
268 // 2.0 at 1 sample to 1.0 at 5.
269 double confidence_factor(int samples) {
270 if (samples > 4) return 1.0;
271 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
272 }
273
274 double get_new_neg_prediction(TruncatedSeq* seq) {
275 return seq->davg() - sigma() * seq->dsd();
276 }
277
278 #ifndef PRODUCT
279 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
280 #endif // PRODUCT
281
282 void adjust_concurrent_refinement(double update_rs_time,
283 double update_rs_processed_buffers,
284 double goal_ms);
285
286 uintx no_of_gc_threads() { return _no_of_gc_threads; }
287 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
288
289 double _pause_time_target_ms;
290 double _recorded_young_cset_choice_time_ms;
291 double _recorded_non_young_cset_choice_time_ms;
292 size_t _pending_cards;
293 size_t _max_pending_cards;
294
295 public:
296 // Accessors
297
298 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
299 hr->set_young();
300 hr->install_surv_rate_group(_short_lived_surv_rate_group);
301 hr->set_young_index_in_cset(young_index_in_cset);
302 }
303
304 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
305 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
306 hr->install_surv_rate_group(_survivor_surv_rate_group);
307 hr->set_young_index_in_cset(young_index_in_cset);
308 }
309
310 #ifndef PRODUCT
311 bool verify_young_ages();
312 #endif // PRODUCT
313
314 double get_new_prediction(TruncatedSeq* seq) {
315 return MAX2(seq->davg() + sigma() * seq->dsd(),
316 seq->davg() * confidence_factor(seq->num()));
317 }
318
319 void record_max_rs_lengths(size_t rs_lengths) {
320 _max_rs_lengths = rs_lengths;
321 }
322
323 size_t predict_pending_card_diff() {
324 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
325 if (prediction < 0.00001) {
326 return 0;
327 } else {
328 return (size_t) prediction;
329 }
330 }
331
332 size_t predict_pending_cards() {
333 size_t max_pending_card_num = _g1->max_pending_card_num();
334 size_t diff = predict_pending_card_diff();
335 size_t prediction;
336 if (diff > max_pending_card_num) {
337 prediction = max_pending_card_num;
338 } else {
339 prediction = max_pending_card_num - diff;
340 }
341
342 return prediction;
343 }
344
345 size_t predict_rs_length_diff() {
346 return (size_t) get_new_prediction(_rs_length_diff_seq);
347 }
348
349 double predict_alloc_rate_ms() {
350 return get_new_prediction(_alloc_rate_ms_seq);
351 }
352
353 double predict_cost_per_card_ms() {
354 return get_new_prediction(_cost_per_card_ms_seq);
355 }
356
357 double predict_rs_update_time_ms(size_t pending_cards) {
358 return (double) pending_cards * predict_cost_per_card_ms();
359 }
360
361 double predict_young_cards_per_entry_ratio() {
362 return get_new_prediction(_young_cards_per_entry_ratio_seq);
363 }
364
365 double predict_mixed_cards_per_entry_ratio() {
366 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
367 return predict_young_cards_per_entry_ratio();
368 } else {
369 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
370 }
371 }
372
373 size_t predict_young_card_num(size_t rs_length) {
374 return (size_t) ((double) rs_length *
375 predict_young_cards_per_entry_ratio());
376 }
377
378 size_t predict_non_young_card_num(size_t rs_length) {
379 return (size_t) ((double) rs_length *
380 predict_mixed_cards_per_entry_ratio());
381 }
382
383 double predict_rs_scan_time_ms(size_t card_num) {
384 if (gcs_are_young()) {
385 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
386 } else {
387 return predict_mixed_rs_scan_time_ms(card_num);
388 }
389 }
390
391 double predict_mixed_rs_scan_time_ms(size_t card_num) {
392 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
393 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
394 } else {
395 return (double) (card_num *
396 get_new_prediction(_mixed_cost_per_entry_ms_seq));
397 }
398 }
399
400 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
401 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
402 return (1.1 * (double) bytes_to_copy) *
403 get_new_prediction(_cost_per_byte_ms_seq);
404 } else {
405 return (double) bytes_to_copy *
406 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
407 }
408 }
409
410 double predict_object_copy_time_ms(size_t bytes_to_copy) {
411 if (_in_marking_window && !_in_marking_window_im) {
412 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
413 } else {
414 return (double) bytes_to_copy *
415 get_new_prediction(_cost_per_byte_ms_seq);
416 }
417 }
418
419 double predict_constant_other_time_ms() {
420 return get_new_prediction(_constant_other_time_ms_seq);
421 }
422
423 double predict_young_other_time_ms(size_t young_num) {
424 return (double) young_num *
425 get_new_prediction(_young_other_cost_per_region_ms_seq);
426 }
427
428 double predict_non_young_other_time_ms(size_t non_young_num) {
429 return (double) non_young_num *
430 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
431 }
432
433 void check_if_region_is_too_expensive(double predicted_time_ms);
434
435 double predict_young_collection_elapsed_time_ms(size_t adjustment);
436 double predict_base_elapsed_time_ms(size_t pending_cards);
437 double predict_base_elapsed_time_ms(size_t pending_cards,
438 size_t scanned_cards);
439 size_t predict_bytes_to_copy(HeapRegion* hr);
440 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
441
442 void set_recorded_rs_lengths(size_t rs_lengths);
443
444 size_t cset_region_length() { return young_cset_region_length() +
445 old_cset_region_length(); }
446 size_t young_cset_region_length() { return eden_cset_region_length() +
447 survivor_cset_region_length(); }
448
449 void record_young_free_cset_time_ms(double time_ms) {
450 _recorded_young_free_cset_time_ms = time_ms;
451 }
452
453 void record_non_young_free_cset_time_ms(double time_ms) {
454 _recorded_non_young_free_cset_time_ms = time_ms;
455 }
456
457 double predict_young_gc_eff() {
458 return get_new_neg_prediction(_young_gc_eff_seq);
459 }
460
461 double predict_survivor_regions_evac_time();
462
463 void cset_regions_freed() {
464 bool propagate = _last_gc_was_young && !_in_marking_window;
465 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
466 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
467 // also call it on any more surv rate groups
468 }
469
470 void set_known_garbage_bytes(size_t known_garbage_bytes) {
471 _known_garbage_bytes = known_garbage_bytes;
472 size_t heap_bytes = _g1->capacity();
473 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
474 }
475
476 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
477 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
478
479 _known_garbage_bytes -= known_garbage_bytes;
480 size_t heap_bytes = _g1->capacity();
481 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
482 }
483
484 G1MMUTracker* mmu_tracker() {
485 return _mmu_tracker;
486 }
487
488 double max_pause_time_ms() {
489 return _mmu_tracker->max_gc_time() * 1000.0;
490 }
491
492 double predict_remark_time_ms() {
493 return get_new_prediction(_concurrent_mark_remark_times_ms);
494 }
495
496 double predict_cleanup_time_ms() {
497 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
498 }
499
500 // Returns an estimate of the survival rate of the region at yg-age
501 // "yg_age".
502 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
503 TruncatedSeq* seq = surv_rate_group->get_seq(age);
504 if (seq->num() == 0)
505 gclog_or_tty->print("BARF! age is %d", age);
506 guarantee( seq->num() > 0, "invariant" );
507 double pred = get_new_prediction(seq);
508 if (pred > 1.0)
509 pred = 1.0;
510 return pred;
511 }
512
513 double predict_yg_surv_rate(int age) {
514 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
515 }
516
517 double accum_yg_surv_rate_pred(int age) {
518 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
519 }
520
521 private:
522 void print_stats(int level, const char* str, double value);
523 void print_stats(int level, const char* str, int value);
524
525 void print_par_stats(int level, const char* str, double* data);
526 void print_par_sizes(int level, const char* str, double* data);
527
528 void check_other_times(int level,
529 NumberSeq* other_times_ms,
530 NumberSeq* calc_other_times_ms) const;
531
532 void print_summary (PauseSummary* stats) const;
533
534 void print_summary (int level, const char* str, NumberSeq* seq) const;
535 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
536
537 double avg_value (double* data);
538 double max_value (double* data);
539 double sum_of_values (double* data);
540 double max_sum (double* data1, double* data2);
541
542 double _last_pause_time_ms;
543
544 size_t _bytes_in_collection_set_before_gc;
545 size_t _bytes_copied_during_gc;
546
547 // Used to count used bytes in CS.
548 friend class CountCSClosure;
549
550 // Statistics kept per GC stoppage, pause or full.
551 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
552
553 // Add a new GC of the given duration and end time to the record.
554 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
555
556 // The head of the list (via "next_in_collection_set()") representing the
557 // current collection set. Set from the incrementally built collection
558 // set at the start of the pause.
559 HeapRegion* _collection_set;
560
561 // The number of bytes in the collection set before the pause. Set from
562 // the incrementally built collection set at the start of an evacuation
563 // pause.
564 size_t _collection_set_bytes_used_before;
565
566 // The associated information that is maintained while the incremental
567 // collection set is being built with young regions. Used to populate
568 // the recorded info for the evacuation pause.
569
570 enum CSetBuildType {
571 Active, // We are actively building the collection set
572 Inactive // We are not actively building the collection set
573 };
574
575 CSetBuildType _inc_cset_build_state;
576
577 // The head of the incrementally built collection set.
578 HeapRegion* _inc_cset_head;
579
580 // The tail of the incrementally built collection set.
581 HeapRegion* _inc_cset_tail;
582
583 // The number of bytes in the incrementally built collection set.
584 // Used to set _collection_set_bytes_used_before at the start of
585 // an evacuation pause.
586 size_t _inc_cset_bytes_used_before;
587
588 // Used to record the highest end of heap region in collection set
589 HeapWord* _inc_cset_max_finger;
590
591 // The RSet lengths recorded for regions in the collection set
592 // (updated by the periodic sampling of the regions in the
593 // young list/collection set).
594 size_t _inc_cset_recorded_rs_lengths;
595
596 // The predicted elapsed time it will take to collect the regions
597 // in the collection set (updated by the periodic sampling of the
598 // regions in the young list/collection set).
599 double _inc_cset_predicted_elapsed_time_ms;
600
601 // Stash a pointer to the g1 heap.
602 G1CollectedHeap* _g1;
603
604 // The ratio of gc time to elapsed time, computed over recent pauses.
605 double _recent_avg_pause_time_ratio;
606
607 double recent_avg_pause_time_ratio() {
608 return _recent_avg_pause_time_ratio;
609 }
610
611 // At the end of a pause we check the heap occupancy and we decide
612 // whether we will start a marking cycle during the next pause. If
613 // we decide that we want to do that, we will set this parameter to
614 // true. So, this parameter will stay true between the end of a
615 // pause and the beginning of a subsequent pause (not necessarily
616 // the next one, see the comments on the next field) when we decide
617 // that we will indeed start a marking cycle and do the initial-mark
618 // work.
619 volatile bool _initiate_conc_mark_if_possible;
620
621 // If initiate_conc_mark_if_possible() is set at the beginning of a
622 // pause, it is a suggestion that the pause should start a marking
623 // cycle by doing the initial-mark work. However, it is possible
624 // that the concurrent marking thread is still finishing up the
625 // previous marking cycle (e.g., clearing the next marking
626 // bitmap). If that is the case we cannot start a new cycle and
627 // we'll have to wait for the concurrent marking thread to finish
628 // what it is doing. In this case we will postpone the marking cycle
629 // initiation decision for the next pause. When we eventually decide
630 // to start a cycle, we will set _during_initial_mark_pause which
631 // will stay true until the end of the initial-mark pause and it's
632 // the condition that indicates that a pause is doing the
633 // initial-mark work.
634 volatile bool _during_initial_mark_pause;
635
636 bool _should_revert_to_young_gcs;
637 bool _last_young_gc;
638
639 // This set of variables tracks the collector efficiency, in order to
640 // determine whether we should initiate a new marking.
641 double _cur_mark_stop_world_time_ms;
642 double _mark_remark_start_sec;
643 double _mark_cleanup_start_sec;
644 double _mark_closure_time_ms;
645
646 // Update the young list target length either by setting it to the
647 // desired fixed value or by calculating it using G1's pause
648 // prediction model. If no rs_lengths parameter is passed, predict
649 // the RS lengths using the prediction model, otherwise use the
650 // given rs_lengths as the prediction.
651 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
652
653 // Calculate and return the minimum desired young list target
654 // length. This is the minimum desired young list length according
655 // to the user's inputs.
656 size_t calculate_young_list_desired_min_length(size_t base_min_length);
657
658 // Calculate and return the maximum desired young list target
659 // length. This is the maximum desired young list length according
660 // to the user's inputs.
661 size_t calculate_young_list_desired_max_length();
662
663 // Calculate and return the maximum young list target length that
664 // can fit into the pause time goal. The parameters are: rs_lengths
665 // represent the prediction of how large the young RSet lengths will
666 // be, base_min_length is the alreay existing number of regions in
667 // the young list, min_length and max_length are the desired min and
668 // max young list length according to the user's inputs.
669 size_t calculate_young_list_target_length(size_t rs_lengths,
670 size_t base_min_length,
671 size_t desired_min_length,
672 size_t desired_max_length);
673
674 // Check whether a given young length (young_length) fits into the
675 // given target pause time and whether the prediction for the amount
676 // of objects to be copied for the given length will fit into the
677 // given free space (expressed by base_free_regions). It is used by
678 // calculate_young_list_target_length().
679 bool predict_will_fit(size_t young_length, double base_time_ms,
680 size_t base_free_regions, double target_pause_time_ms);
681
682 // Count the number of bytes used in the CS.
683 void count_CS_bytes_used();
684
685 void update_young_list_size_using_newratio(size_t number_of_heap_regions);
686
687 public:
688
689 G1CollectorPolicy();
690
691 virtual G1CollectorPolicy* as_g1_policy() { return this; }
692
693 virtual CollectorPolicy::Name kind() {
694 return CollectorPolicy::G1CollectorPolicyKind;
695 }
696
697 // Check the current value of the young list RSet lengths and
698 // compare it against the last prediction. If the current value is
699 // higher, recalculate the young list target length prediction.
700 void revise_young_list_target_length_if_necessary();
701
702 size_t bytes_in_collection_set() {
703 return _bytes_in_collection_set_before_gc;
704 }
705
706 unsigned calc_gc_alloc_time_stamp() {
707 return _all_pause_times_ms->num() + 1;
708 }
709
710 // This should be called after the heap is resized.
711 void record_new_heap_size(size_t new_number_of_regions);
712
713 public:
714
715 void init();
716
717 // Create jstat counters for the policy.
718 virtual void initialize_gc_policy_counters();
719
720 virtual HeapWord* mem_allocate_work(size_t size,
721 bool is_tlab,
722 bool* gc_overhead_limit_was_exceeded);
723
724 // This method controls how a collector handles one or more
725 // of its generations being fully allocated.
726 virtual HeapWord* satisfy_failed_allocation(size_t size,
727 bool is_tlab);
728
729 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
730
731 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
732
733 // Update the heuristic info to record a collection pause of the given
734 // start time, where the given number of bytes were used at the start.
735 // This may involve changing the desired size of a collection set.
736
737 void record_stop_world_start();
738
739 void record_collection_pause_start(double start_time_sec, size_t start_used);
740
741 // Must currently be called while the world is stopped.
742 void record_concurrent_mark_init_end(double
743 mark_init_elapsed_time_ms);
744
745 void record_mark_closure_time(double mark_closure_time_ms) {
746 _mark_closure_time_ms = mark_closure_time_ms;
747 }
748
749 void record_concurrent_mark_remark_start();
750 void record_concurrent_mark_remark_end();
751
752 void record_concurrent_mark_cleanup_start();
753 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
754 void record_concurrent_mark_cleanup_completed();
755
756 void record_concurrent_pause();
757 void record_concurrent_pause_end();
758
759 void record_collection_pause_end(int no_of_gc_threads);
760 void print_heap_transition();
761
762 // Record the fact that a full collection occurred.
763 void record_full_collection_start();
764 void record_full_collection_end();
765
766 void record_gc_worker_start_time(int worker_i, double ms) {
767 _par_last_gc_worker_start_times_ms[worker_i] = ms;
768 }
769
770 void record_ext_root_scan_time(int worker_i, double ms) {
771 _par_last_ext_root_scan_times_ms[worker_i] = ms;
772 }
773
774 void record_mark_stack_scan_time(int worker_i, double ms) {
775 _par_last_mark_stack_scan_times_ms[worker_i] = ms;
776 }
777
778 void record_satb_drain_time(double ms) {
779 assert(_g1->mark_in_progress(), "shouldn't be here otherwise");
780 _cur_satb_drain_time_ms = ms;
781 }
782
783 void record_update_rs_time(int thread, double ms) {
784 _par_last_update_rs_times_ms[thread] = ms;
785 }
786
787 void record_update_rs_processed_buffers (int thread,
788 double processed_buffers) {
789 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
790 }
791
792 void record_scan_rs_time(int thread, double ms) {
793 _par_last_scan_rs_times_ms[thread] = ms;
794 }
795
796 void reset_obj_copy_time(int thread) {
797 _par_last_obj_copy_times_ms[thread] = 0.0;
798 }
799
800 void reset_obj_copy_time() {
801 reset_obj_copy_time(0);
802 }
803
804 void record_obj_copy_time(int thread, double ms) {
805 _par_last_obj_copy_times_ms[thread] += ms;
806 }
807
808 void record_termination(int thread, double ms, size_t attempts) {
809 _par_last_termination_times_ms[thread] = ms;
810 _par_last_termination_attempts[thread] = (double) attempts;
811 }
812
813 void record_gc_worker_end_time(int worker_i, double ms) {
814 _par_last_gc_worker_end_times_ms[worker_i] = ms;
815 }
816
817 void record_pause_time_ms(double ms) {
818 _last_pause_time_ms = ms;
819 }
820
821 void record_clear_ct_time(double ms) {
822 _cur_clear_ct_time_ms = ms;
823 }
824
825 void record_par_time(double ms) {
826 _cur_collection_par_time_ms = ms;
827 }
828
829 void record_aux_start_time(int i) {
830 guarantee(i < _aux_num, "should be within range");
831 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
832 }
833
834 void record_aux_end_time(int i) {
835 guarantee(i < _aux_num, "should be within range");
836 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
837 _cur_aux_times_set[i] = true;
838 _cur_aux_times_ms[i] += ms;
839 }
840
841 void record_ref_proc_time(double ms) {
842 _cur_ref_proc_time_ms = ms;
843 }
844
845 void record_ref_enq_time(double ms) {
846 _cur_ref_enq_time_ms = ms;
847 }
848
849 #ifndef PRODUCT
850 void record_cc_clear_time(double ms) {
851 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
852 _min_clear_cc_time_ms = ms;
853 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
854 _max_clear_cc_time_ms = ms;
855 _cur_clear_cc_time_ms = ms;
856 _cum_clear_cc_time_ms += ms;
857 _num_cc_clears++;
858 }
859 #endif
860
861 // Record how much space we copied during a GC. This is typically
862 // called when a GC alloc region is being retired.
863 void record_bytes_copied_during_gc(size_t bytes) {
864 _bytes_copied_during_gc += bytes;
865 }
866
867 // The amount of space we copied during a GC.
868 size_t bytes_copied_during_gc() {
869 return _bytes_copied_during_gc;
870 }
871
872 // Choose a new collection set. Marks the chosen regions as being
873 // "in_collection_set", and links them together. The head and number of
874 // the collection set are available via access methods.
875 void choose_collection_set(double target_pause_time_ms);
876
877 // The head of the list (via "next_in_collection_set()") representing the
878 // current collection set.
879 HeapRegion* collection_set() { return _collection_set; }
880
881 void clear_collection_set() { _collection_set = NULL; }
882
883 // Add old region "hr" to the CSet.
884 void add_old_region_to_cset(HeapRegion* hr);
885
886 // Incremental CSet Support
887
888 // The head of the incrementally built collection set.
889 HeapRegion* inc_cset_head() { return _inc_cset_head; }
890
891 // The tail of the incrementally built collection set.
892 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
893
894 // Initialize incremental collection set info.
895 void start_incremental_cset_building();
896
897 void clear_incremental_cset() {
898 _inc_cset_head = NULL;
899 _inc_cset_tail = NULL;
900 }
901
902 // Stop adding regions to the incremental collection set
903 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
904
905 // Add/remove information about hr to the aggregated information
906 // for the incrementally built collection set.
907 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
908 void remove_from_incremental_cset_info(HeapRegion* hr);
909
910 // Update information about hr in the aggregated information for
911 // the incrementally built collection set.
912 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
913
914 private:
915 // Update the incremental cset information when adding a region
916 // (should not be called directly).
917 void add_region_to_incremental_cset_common(HeapRegion* hr);
918
919 public:
920 // Add hr to the LHS of the incremental collection set.
921 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
922
923 // Add hr to the RHS of the incremental collection set.
924 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
925
926 #ifndef PRODUCT
927 void print_collection_set(HeapRegion* list_head, outputStream* st);
928 #endif // !PRODUCT
929
930 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
931 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
932 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
933
934 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
935 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
936 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
937
938 // This sets the initiate_conc_mark_if_possible() flag to start a
939 // new cycle, as long as we are not already in one. It's best if it
940 // is called during a safepoint when the test whether a cycle is in
941 // progress or not is stable.
942 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
943
944 // This is called at the very beginning of an evacuation pause (it
945 // has to be the first thing that the pause does). If
946 // initiate_conc_mark_if_possible() is true, and the concurrent
947 // marking thread has completed its work during the previous cycle,
948 // it will set during_initial_mark_pause() to so that the pause does
949 // the initial-mark work and start a marking cycle.
950 void decide_on_conc_mark_initiation();
951
952 // If an expansion would be appropriate, because recent GC overhead had
953 // exceeded the desired limit, return an amount to expand by.
954 size_t expansion_amount();
955
956 #ifndef PRODUCT
957 // Check any appropriate marked bytes info, asserting false if
958 // something's wrong, else returning "true".
959 bool assertMarkedBytesDataOK();
960 #endif
961
962 // Print tracing information.
963 void print_tracing_info() const;
964
965 // Print stats on young survival ratio
966 void print_yg_surv_rate_info() const;
967
968 void finished_recalculating_age_indexes(bool is_survivors) {
969 if (is_survivors) {
970 _survivor_surv_rate_group->finished_recalculating_age_indexes();
971 } else {
972 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
973 }
974 // do that for any other surv rate groups
975 }
976
977 bool is_young_list_full() {
978 size_t young_list_length = _g1->young_list()->length();
979 size_t young_list_target_length = _young_list_target_length;
980 return young_list_length >= young_list_target_length;
981 }
982
983 bool can_expand_young_list() {
984 size_t young_list_length = _g1->young_list()->length();
985 size_t young_list_max_length = _young_list_max_length;
986 return young_list_length < young_list_max_length;
987 }
988
989 size_t young_list_max_length() {
990 return _young_list_max_length;
991 }
992
993 bool gcs_are_young() {
994 return _gcs_are_young;
995 }
996 void set_gcs_are_young(bool gcs_are_young) {
997 _gcs_are_young = gcs_are_young;
998 }
999
1000 bool adaptive_young_list_length() {
1001 return _adaptive_young_list_length;
1002 }
1003 void set_adaptive_young_list_length(bool adaptive_young_list_length) {
1004 _adaptive_young_list_length = adaptive_young_list_length;
1005 }
1006
1007 inline double get_gc_eff_factor() {
1008 double ratio = _known_garbage_ratio;
1009
1010 double square = ratio * ratio;
1011 // square = square * square;
1012 double ret = square * 9.0 + 1.0;
1013 #if 0
1014 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1015 #endif // 0
1016 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1017 return ret;
1018 }
1019
1020 private:
1021 //
1022 // Survivor regions policy.
1023 //
1024
1025 // Current tenuring threshold, set to 0 if the collector reaches the
1026 // maximum amount of suvivors regions.
1027 int _tenuring_threshold;
1028
1029 // The limit on the number of regions allocated for survivors.
1030 size_t _max_survivor_regions;
1031
1032 // For reporting purposes.
1033 size_t _eden_bytes_before_gc;
1034 size_t _survivor_bytes_before_gc;
1035 size_t _capacity_before_gc;
1036
1037 // The amount of survor regions after a collection.
1038 size_t _recorded_survivor_regions;
1039 // List of survivor regions.
1040 HeapRegion* _recorded_survivor_head;
1041 HeapRegion* _recorded_survivor_tail;
1042
1043 ageTable _survivors_age_table;
1044
1045 public:
1046
1047 inline GCAllocPurpose
1048 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1049 if (age < _tenuring_threshold && src_region->is_young()) {
1050 return GCAllocForSurvived;
1051 } else {
1052 return GCAllocForTenured;
1053 }
1054 }
1055
1056 inline bool track_object_age(GCAllocPurpose purpose) {
1057 return purpose == GCAllocForSurvived;
1058 }
1059
1060 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1061
1062 size_t max_regions(int purpose);
1063
1064 // The limit on regions for a particular purpose is reached.
1065 void note_alloc_region_limit_reached(int purpose) {
1066 if (purpose == GCAllocForSurvived) {
1067 _tenuring_threshold = 0;
1068 }
1069 }
1070
1071 void note_start_adding_survivor_regions() {
1072 _survivor_surv_rate_group->start_adding_regions();
1073 }
1074
1075 void note_stop_adding_survivor_regions() {
1076 _survivor_surv_rate_group->stop_adding_regions();
1077 }
1078
1079 void record_survivor_regions(size_t regions,
1080 HeapRegion* head,
1081 HeapRegion* tail) {
1082 _recorded_survivor_regions = regions;
1083 _recorded_survivor_head = head;
1084 _recorded_survivor_tail = tail;
1085 }
1086
1087 size_t recorded_survivor_regions() {
1088 return _recorded_survivor_regions;
1089 }
1090
1091 void record_thread_age_table(ageTable* age_table)
1092 {
1093 _survivors_age_table.merge_par(age_table);
1094 }
1095
1096 void update_max_gc_locker_expansion();
1097
1098 // Calculates survivor space parameters.
1099 void update_survivors_policy();
1100
1101 };
1102
1103 // This should move to some place more general...
1104
1105 // If we have "n" measurements, and we've kept track of their "sum" and the
1106 // "sum_of_squares" of the measurements, this returns the variance of the
1107 // sequence.
1108 inline double variance(int n, double sum_of_squares, double sum) {
1109 double n_d = (double)n;
1110 double avg = sum/n_d;
1111 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1112 }
1113
1114 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP