1 /*
2 * Copyright (c) 2001, 2010, 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 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectorPolicy.cpp.incl"
27
28 #define PREDICTIONS_VERBOSE 0
29
30 // <NEW PREDICTION>
31
32 // Different defaults for different number of GC threads
33 // They were chosen by running GCOld and SPECjbb on debris with different
34 // numbers of GC threads and choosing them based on the results
35
36 // all the same
37 static double rs_length_diff_defaults[] = {
38 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
39 };
40
41 static double cost_per_card_ms_defaults[] = {
42 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
43 };
44
45 // all the same
46 static double fully_young_cards_per_entry_ratio_defaults[] = {
47 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
48 };
49
50 static double cost_per_entry_ms_defaults[] = {
51 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
52 };
53
54 static double cost_per_byte_ms_defaults[] = {
55 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
56 };
57
58 // these should be pretty consistent
59 static double constant_other_time_ms_defaults[] = {
60 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
61 };
62
63
64 static double young_other_cost_per_region_ms_defaults[] = {
65 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
66 };
67
68 static double non_young_other_cost_per_region_ms_defaults[] = {
69 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
70 };
71
72 // </NEW PREDICTION>
73
74 G1CollectorPolicy::G1CollectorPolicy() :
75 _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
76 _n_pauses(0),
77 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
78 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
79 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
80 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
81 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
82 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
83 _all_pause_times_ms(new NumberSeq()),
84 _stop_world_start(0.0),
85 _all_stop_world_times_ms(new NumberSeq()),
86 _all_yield_times_ms(new NumberSeq()),
87
88 _all_mod_union_times_ms(new NumberSeq()),
89
90 _summary(new Summary()),
91
92 #ifndef PRODUCT
93 _cur_clear_ct_time_ms(0.0),
94 _min_clear_cc_time_ms(-1.0),
95 _max_clear_cc_time_ms(-1.0),
96 _cur_clear_cc_time_ms(0.0),
97 _cum_clear_cc_time_ms(0.0),
98 _num_cc_clears(0L),
99 #endif
100
101 _region_num_young(0),
102 _region_num_tenured(0),
103 _prev_region_num_young(0),
104 _prev_region_num_tenured(0),
105
106 _aux_num(10),
107 _all_aux_times_ms(new NumberSeq[_aux_num]),
108 _cur_aux_start_times_ms(new double[_aux_num]),
109 _cur_aux_times_ms(new double[_aux_num]),
110 _cur_aux_times_set(new bool[_aux_num]),
111
112 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
113 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
114 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
115
116 // <NEW PREDICTION>
117
118 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
119 _prev_collection_pause_end_ms(0.0),
120 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
121 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
122 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
123 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
124 _partially_young_cards_per_entry_ratio_seq(
125 new TruncatedSeq(TruncatedSeqLength)),
126 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
127 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
128 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
129 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
130 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
131 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
132 _non_young_other_cost_per_region_ms_seq(
133 new TruncatedSeq(TruncatedSeqLength)),
134
135 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
136 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
137 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
138
139 _pause_time_target_ms((double) MaxGCPauseMillis),
140
141 // </NEW PREDICTION>
142
143 _in_young_gc_mode(false),
144 _full_young_gcs(true),
145 _full_young_pause_num(0),
146 _partial_young_pause_num(0),
147
148 _during_marking(false),
149 _in_marking_window(false),
150 _in_marking_window_im(false),
151
152 _known_garbage_ratio(0.0),
153 _known_garbage_bytes(0),
154
155 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
156
157 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
158
159 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
160 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
161
162 _recent_avg_pause_time_ratio(0.0),
163 _num_markings(0),
164 _n_marks(0),
165 _n_pauses_at_mark_end(0),
166
167 _all_full_gc_times_ms(new NumberSeq()),
168
169 // G1PausesBtwnConcMark defaults to -1
170 // so the hack is to do the cast QQQ FIXME
171 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
172 _n_marks_since_last_pause(0),
173 _initiate_conc_mark_if_possible(false),
174 _during_initial_mark_pause(false),
175 _should_revert_to_full_young_gcs(false),
176 _last_full_young_gc(false),
177
178 _prev_collection_pause_used_at_end_bytes(0),
179
180 _collection_set(NULL),
181 _collection_set_size(0),
182 _collection_set_bytes_used_before(0),
183
184 // Incremental CSet attributes
185 _inc_cset_build_state(Inactive),
186 _inc_cset_head(NULL),
187 _inc_cset_tail(NULL),
188 _inc_cset_size(0),
189 _inc_cset_young_index(0),
190 _inc_cset_bytes_used_before(0),
191 _inc_cset_max_finger(NULL),
192 _inc_cset_recorded_young_bytes(0),
193 _inc_cset_recorded_rs_lengths(0),
194 _inc_cset_predicted_elapsed_time_ms(0.0),
195 _inc_cset_predicted_bytes_to_copy(0),
196
197 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
198 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
199 #endif // _MSC_VER
200
201 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
202 G1YoungSurvRateNumRegionsSummary)),
203 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
204 G1YoungSurvRateNumRegionsSummary)),
205 // add here any more surv rate groups
206 _recorded_survivor_regions(0),
207 _recorded_survivor_head(NULL),
208 _recorded_survivor_tail(NULL),
209 _survivors_age_table(true),
210
211 _gc_overhead_perc(0.0)
212
213 {
214 // Set up the region size and associated fields. Given that the
215 // policy is created before the heap, we have to set this up here,
216 // so it's done as soon as possible.
217 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
218 HeapRegionRemSet::setup_remset_size();
219
220 // Verify PLAB sizes
221 const uint region_size = HeapRegion::GrainWords;
222 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
223 char buffer[128];
224 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
225 OldPLABSize > region_size ? "Old" : "Young", region_size);
226 vm_exit_during_initialization(buffer);
227 }
228
229 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
230 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
231
232 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
233 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
234 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
235
236 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
237 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
238
239 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
240
241 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
242
243 _par_last_termination_times_ms = new double[_parallel_gc_threads];
244 _par_last_termination_attempts = new double[_parallel_gc_threads];
245 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
246
247 // start conservatively
248 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
249
250 // <NEW PREDICTION>
251
252 int index;
253 if (ParallelGCThreads == 0)
254 index = 0;
255 else if (ParallelGCThreads > 8)
256 index = 7;
257 else
258 index = ParallelGCThreads - 1;
259
260 _pending_card_diff_seq->add(0.0);
261 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
262 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
263 _fully_young_cards_per_entry_ratio_seq->add(
264 fully_young_cards_per_entry_ratio_defaults[index]);
265 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
266 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
267 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
268 _young_other_cost_per_region_ms_seq->add(
269 young_other_cost_per_region_ms_defaults[index]);
270 _non_young_other_cost_per_region_ms_seq->add(
271 non_young_other_cost_per_region_ms_defaults[index]);
272
273 // </NEW PREDICTION>
274
275 // Below, we might need to calculate the pause time target based on
276 // the pause interval. When we do so we are going to give G1 maximum
277 // flexibility and allow it to do pauses when it needs to. So, we'll
278 // arrange that the pause interval to be pause time target + 1 to
279 // ensure that a) the pause time target is maximized with respect to
280 // the pause interval and b) we maintain the invariant that pause
281 // time target < pause interval. If the user does not want this
282 // maximum flexibility, they will have to set the pause interval
283 // explicitly.
284
285 // First make sure that, if either parameter is set, its value is
286 // reasonable.
287 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
288 if (MaxGCPauseMillis < 1) {
289 vm_exit_during_initialization("MaxGCPauseMillis should be "
290 "greater than 0");
291 }
292 }
293 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
294 if (GCPauseIntervalMillis < 1) {
295 vm_exit_during_initialization("GCPauseIntervalMillis should be "
296 "greater than 0");
297 }
298 }
299
300 // Then, if the pause time target parameter was not set, set it to
301 // the default value.
302 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
303 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
304 // The default pause time target in G1 is 200ms
305 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
306 } else {
307 // We do not allow the pause interval to be set without the
308 // pause time target
309 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
310 "without setting MaxGCPauseMillis");
311 }
312 }
313
314 // Then, if the interval parameter was not set, set it according to
315 // the pause time target (this will also deal with the case when the
316 // pause time target is the default value).
317 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
318 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
319 }
320
321 // Finally, make sure that the two parameters are consistent.
322 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
323 char buffer[256];
324 jio_snprintf(buffer, 256,
325 "MaxGCPauseMillis (%u) should be less than "
326 "GCPauseIntervalMillis (%u)",
327 MaxGCPauseMillis, GCPauseIntervalMillis);
328 vm_exit_during_initialization(buffer);
329 }
330
331 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
332 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
333 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
334 _sigma = (double) G1ConfidencePercent / 100.0;
335
336 // start conservatively (around 50ms is about right)
337 _concurrent_mark_init_times_ms->add(0.05);
338 _concurrent_mark_remark_times_ms->add(0.05);
339 _concurrent_mark_cleanup_times_ms->add(0.20);
340 _tenuring_threshold = MaxTenuringThreshold;
341
342 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
343 // fixed, then _max_survivor_regions will be calculated at
344 // calculate_young_list_target_length during initialization
345 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
346
347 assert(GCTimeRatio > 0,
348 "we should have set it to a default value set_g1_gc_flags() "
349 "if a user set it to 0");
350 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
351
352 initialize_all();
353 }
354
355 // Increment "i", mod "len"
356 static void inc_mod(int& i, int len) {
357 i++; if (i == len) i = 0;
358 }
359
360 void G1CollectorPolicy::initialize_flags() {
361 set_min_alignment(HeapRegion::GrainBytes);
362 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
363 if (SurvivorRatio < 1) {
364 vm_exit_during_initialization("Invalid survivor ratio specified");
365 }
366 CollectorPolicy::initialize_flags();
367 }
368
369 // The easiest way to deal with the parsing of the NewSize /
370 // MaxNewSize / etc. parameteres is to re-use the code in the
371 // TwoGenerationCollectorPolicy class. This is similar to what
372 // ParallelScavenge does with its GenerationSizer class (see
373 // ParallelScavengeHeap::initialize()). We might change this in the
374 // future, but it's a good start.
375 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
376 size_t size_to_region_num(size_t byte_size) {
377 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
378 }
379
380 public:
381 G1YoungGenSizer() {
382 initialize_flags();
383 initialize_size_info();
384 }
385
386 size_t min_young_region_num() {
387 return size_to_region_num(_min_gen0_size);
388 }
389 size_t initial_young_region_num() {
390 return size_to_region_num(_initial_gen0_size);
391 }
392 size_t max_young_region_num() {
393 return size_to_region_num(_max_gen0_size);
394 }
395 };
396
397 void G1CollectorPolicy::init() {
398 // Set aside an initial future to_space.
399 _g1 = G1CollectedHeap::heap();
400
401 assert(Heap_lock->owned_by_self(), "Locking discipline.");
402
403 initialize_gc_policy_counters();
404
405 if (G1Gen) {
406 _in_young_gc_mode = true;
407
408 G1YoungGenSizer sizer;
409 size_t initial_region_num = sizer.initial_young_region_num();
410
411 if (UseAdaptiveSizePolicy) {
412 set_adaptive_young_list_length(true);
413 _young_list_fixed_length = 0;
414 } else {
415 set_adaptive_young_list_length(false);
416 _young_list_fixed_length = initial_region_num;
417 }
418 _free_regions_at_end_of_collection = _g1->free_regions();
419 calculate_young_list_min_length();
420 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
421 calculate_young_list_target_length();
422 } else {
423 _young_list_fixed_length = 0;
424 _in_young_gc_mode = false;
425 }
426
427 // We may immediately start allocating regions and placing them on the
428 // collection set list. Initialize the per-collection set info
429 start_incremental_cset_building();
430 }
431
432 // Create the jstat counters for the policy.
433 void G1CollectorPolicy::initialize_gc_policy_counters()
434 {
435 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
436 }
437
438 void G1CollectorPolicy::calculate_young_list_min_length() {
439 _young_list_min_length = 0;
440
441 if (!adaptive_young_list_length())
442 return;
443
444 if (_alloc_rate_ms_seq->num() > 3) {
445 double now_sec = os::elapsedTime();
446 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
447 double alloc_rate_ms = predict_alloc_rate_ms();
448 int min_regions = (int) ceil(alloc_rate_ms * when_ms);
449 int current_region_num = (int) _g1->young_list()->length();
450 _young_list_min_length = min_regions + current_region_num;
451 }
452 }
453
454 void G1CollectorPolicy::calculate_young_list_target_length() {
455 if (adaptive_young_list_length()) {
456 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
457 calculate_young_list_target_length(rs_lengths);
458 } else {
459 if (full_young_gcs())
460 _young_list_target_length = _young_list_fixed_length;
461 else
462 _young_list_target_length = _young_list_fixed_length / 2;
463
464 _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
465 }
466 calculate_survivors_policy();
467 }
468
469 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
470 guarantee( adaptive_young_list_length(), "pre-condition" );
471 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
472
473 double start_time_sec = os::elapsedTime();
474 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
475 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
476 size_t reserve_regions =
477 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
478
479 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
480 // we are in fully-young mode and there are free regions in the heap
481
482 double survivor_regions_evac_time =
483 predict_survivor_regions_evac_time();
484
485 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
486 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
487 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
488 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
489 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
490 + survivor_regions_evac_time;
491
492 // the result
493 size_t final_young_length = 0;
494
495 size_t init_free_regions =
496 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
497
498 // if we're still under the pause target...
499 if (base_time_ms <= target_pause_time_ms) {
500 // We make sure that the shortest young length that makes sense
501 // fits within the target pause time.
502 size_t min_young_length = 1;
503
504 if (predict_will_fit(min_young_length, base_time_ms,
505 init_free_regions, target_pause_time_ms)) {
506 // The shortest young length will fit within the target pause time;
507 // we'll now check whether the absolute maximum number of young
508 // regions will fit in the target pause time. If not, we'll do
509 // a binary search between min_young_length and max_young_length
510 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
511 size_t max_young_length = abs_max_young_length;
512
513 if (max_young_length > min_young_length) {
514 // Let's check if the initial max young length will fit within the
515 // target pause. If so then there is no need to search for a maximal
516 // young length - we'll return the initial maximum
517
518 if (predict_will_fit(max_young_length, base_time_ms,
519 init_free_regions, target_pause_time_ms)) {
520 // The maximum young length will satisfy the target pause time.
521 // We are done so set min young length to this maximum length.
522 // The code after the loop will then set final_young_length using
523 // the value cached in the minimum length.
524 min_young_length = max_young_length;
525 } else {
526 // The maximum possible number of young regions will not fit within
527 // the target pause time so let's search....
528
529 size_t diff = (max_young_length - min_young_length) / 2;
530 max_young_length = min_young_length + diff;
531
532 while (max_young_length > min_young_length) {
533 if (predict_will_fit(max_young_length, base_time_ms,
534 init_free_regions, target_pause_time_ms)) {
535
536 // The current max young length will fit within the target
537 // pause time. Note we do not exit the loop here. By setting
538 // min = max, and then increasing the max below means that
539 // we will continue searching for an upper bound in the
540 // range [max..max+diff]
541 min_young_length = max_young_length;
542 }
543 diff = (max_young_length - min_young_length) / 2;
544 max_young_length = min_young_length + diff;
545 }
546 // the above loop found a maximal young length that will fit
547 // within the target pause time.
548 }
549 assert(min_young_length <= abs_max_young_length, "just checking");
550 }
551 final_young_length = min_young_length;
552 }
553 }
554 // and we're done!
555
556 // we should have at least one region in the target young length
557 _young_list_target_length =
558 MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
559
560 // let's keep an eye of how long we spend on this calculation
561 // right now, I assume that we'll print it when we need it; we
562 // should really adde it to the breakdown of a pause
563 double end_time_sec = os::elapsedTime();
564 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
565
566 #ifdef TRACE_CALC_YOUNG_LENGTH
567 // leave this in for debugging, just in case
568 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
569 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
570 target_pause_time_ms,
571 _young_list_target_length
572 elapsed_time_ms,
573 full_young_gcs() ? "full" : "partial",
574 during_initial_mark_pause() ? " i-m" : "",
575 _in_marking_window,
576 _in_marking_window_im);
577 #endif // TRACE_CALC_YOUNG_LENGTH
578
579 if (_young_list_target_length < _young_list_min_length) {
580 // bummer; this means that, if we do a pause when the maximal
581 // length dictates, we'll violate the pause spacing target (the
582 // min length was calculate based on the application's current
583 // alloc rate);
584
585 // so, we have to bite the bullet, and allocate the minimum
586 // number. We'll violate our target, but we just can't meet it.
587
588 #ifdef TRACE_CALC_YOUNG_LENGTH
589 // leave this in for debugging, just in case
590 gclog_or_tty->print_cr("adjusted target length from "
591 SIZE_FORMAT " to " SIZE_FORMAT,
592 _young_list_target_length, _young_list_min_length);
593 #endif // TRACE_CALC_YOUNG_LENGTH
594
595 _young_list_target_length = _young_list_min_length;
596 }
597 } else {
598 // we are in a partially-young mode or we've run out of regions (due
599 // to evacuation failure)
600
601 #ifdef TRACE_CALC_YOUNG_LENGTH
602 // leave this in for debugging, just in case
603 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
604 _young_list_min_length);
605 #endif // TRACE_CALC_YOUNG_LENGTH
606 // we'll do the pause as soon as possible by choosing the minimum
607 _young_list_target_length =
608 MAX2(_young_list_min_length, (size_t) 1);
609 }
610
611 _rs_lengths_prediction = rs_lengths;
612 }
613
614 // This is used by: calculate_young_list_target_length(rs_length). It
615 // returns true iff:
616 // the predicted pause time for the given young list will not overflow
617 // the target pause time
618 // and:
619 // the predicted amount of surviving data will not overflow the
620 // the amount of free space available for survivor regions.
621 //
622 bool
623 G1CollectorPolicy::predict_will_fit(size_t young_length,
624 double base_time_ms,
625 size_t init_free_regions,
626 double target_pause_time_ms) {
627
628 if (young_length >= init_free_regions)
629 // end condition 1: not enough space for the young regions
630 return false;
631
632 double accum_surv_rate_adj = 0.0;
633 double accum_surv_rate =
634 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
635
636 size_t bytes_to_copy =
637 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
638
639 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
640
641 double young_other_time_ms =
642 predict_young_other_time_ms(young_length);
643
644 double pause_time_ms =
645 base_time_ms + copy_time_ms + young_other_time_ms;
646
647 if (pause_time_ms > target_pause_time_ms)
648 // end condition 2: over the target pause time
649 return false;
650
651 size_t free_bytes =
652 (init_free_regions - young_length) * HeapRegion::GrainBytes;
653
654 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
655 // end condition 3: out of to-space (conservatively)
656 return false;
657
658 // success!
659 return true;
660 }
661
662 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
663 double survivor_regions_evac_time = 0.0;
664 for (HeapRegion * r = _recorded_survivor_head;
665 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
666 r = r->get_next_young_region()) {
667 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
668 }
669 return survivor_regions_evac_time;
670 }
671
672 void G1CollectorPolicy::check_prediction_validity() {
673 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
674
675 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
676 if (rs_lengths > _rs_lengths_prediction) {
677 // add 10% to avoid having to recalculate often
678 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
679 calculate_young_list_target_length(rs_lengths_prediction);
680 }
681 }
682
683 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
684 bool is_tlab,
685 bool* gc_overhead_limit_was_exceeded) {
686 guarantee(false, "Not using this policy feature yet.");
687 return NULL;
688 }
689
690 // This method controls how a collector handles one or more
691 // of its generations being fully allocated.
692 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
693 bool is_tlab) {
694 guarantee(false, "Not using this policy feature yet.");
695 return NULL;
696 }
697
698
699 #ifndef PRODUCT
700 bool G1CollectorPolicy::verify_young_ages() {
701 HeapRegion* head = _g1->young_list()->first_region();
702 return
703 verify_young_ages(head, _short_lived_surv_rate_group);
704 // also call verify_young_ages on any additional surv rate groups
705 }
706
707 bool
708 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
709 SurvRateGroup *surv_rate_group) {
710 guarantee( surv_rate_group != NULL, "pre-condition" );
711
712 const char* name = surv_rate_group->name();
713 bool ret = true;
714 int prev_age = -1;
715
716 for (HeapRegion* curr = head;
717 curr != NULL;
718 curr = curr->get_next_young_region()) {
719 SurvRateGroup* group = curr->surv_rate_group();
720 if (group == NULL && !curr->is_survivor()) {
721 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
722 ret = false;
723 }
724
725 if (surv_rate_group == group) {
726 int age = curr->age_in_surv_rate_group();
727
728 if (age < 0) {
729 gclog_or_tty->print_cr("## %s: encountered negative age", name);
730 ret = false;
731 }
732
733 if (age <= prev_age) {
734 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
735 "(%d, %d)", name, age, prev_age);
736 ret = false;
737 }
738 prev_age = age;
739 }
740 }
741
742 return ret;
743 }
744 #endif // PRODUCT
745
746 void G1CollectorPolicy::record_full_collection_start() {
747 _cur_collection_start_sec = os::elapsedTime();
748 // Release the future to-space so that it is available for compaction into.
749 _g1->set_full_collection();
750 }
751
752 void G1CollectorPolicy::record_full_collection_end() {
753 // Consider this like a collection pause for the purposes of allocation
754 // since last pause.
755 double end_sec = os::elapsedTime();
756 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
757 double full_gc_time_ms = full_gc_time_sec * 1000.0;
758
759 _all_full_gc_times_ms->add(full_gc_time_ms);
760
761 update_recent_gc_times(end_sec, full_gc_time_ms);
762
763 _g1->clear_full_collection();
764
765 // "Nuke" the heuristics that control the fully/partially young GC
766 // transitions and make sure we start with fully young GCs after the
767 // Full GC.
768 set_full_young_gcs(true);
769 _last_full_young_gc = false;
770 _should_revert_to_full_young_gcs = false;
771 clear_initiate_conc_mark_if_possible();
772 clear_during_initial_mark_pause();
773 _known_garbage_bytes = 0;
774 _known_garbage_ratio = 0.0;
775 _in_marking_window = false;
776 _in_marking_window_im = false;
777
778 _short_lived_surv_rate_group->start_adding_regions();
779 // also call this on any additional surv rate groups
780
781 record_survivor_regions(0, NULL, NULL);
782
783 _prev_region_num_young = _region_num_young;
784 _prev_region_num_tenured = _region_num_tenured;
785
786 _free_regions_at_end_of_collection = _g1->free_regions();
787 // Reset survivors SurvRateGroup.
788 _survivor_surv_rate_group->reset();
789 calculate_young_list_min_length();
790 calculate_young_list_target_length();
791 }
792
793 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
794 _bytes_in_to_space_before_gc += bytes;
795 }
796
797 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
798 _bytes_in_to_space_after_gc += bytes;
799 }
800
801 void G1CollectorPolicy::record_stop_world_start() {
802 _stop_world_start = os::elapsedTime();
803 }
804
805 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
806 size_t start_used) {
807 if (PrintGCDetails) {
808 gclog_or_tty->stamp(PrintGCTimeStamps);
809 gclog_or_tty->print("[GC pause");
810 if (in_young_gc_mode())
811 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
812 }
813
814 assert(_g1->used_regions() == _g1->recalculate_used_regions(),
815 "sanity");
816 assert(_g1->used() == _g1->recalculate_used(), "sanity");
817
818 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
819 _all_stop_world_times_ms->add(s_w_t_ms);
820 _stop_world_start = 0.0;
821
822 _cur_collection_start_sec = start_time_sec;
823 _cur_collection_pause_used_at_start_bytes = start_used;
824 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
825 _pending_cards = _g1->pending_card_num();
826 _max_pending_cards = _g1->max_pending_card_num();
827
828 _bytes_in_to_space_before_gc = 0;
829 _bytes_in_to_space_after_gc = 0;
830 _bytes_in_collection_set_before_gc = 0;
831
832 #ifdef DEBUG
833 // initialise these to something well known so that we can spot
834 // if they are not set properly
835
836 for (int i = 0; i < _parallel_gc_threads; ++i) {
837 _par_last_gc_worker_start_times_ms[i] = -1234.0;
838 _par_last_ext_root_scan_times_ms[i] = -1234.0;
839 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
840 _par_last_update_rs_times_ms[i] = -1234.0;
841 _par_last_update_rs_processed_buffers[i] = -1234.0;
842 _par_last_scan_rs_times_ms[i] = -1234.0;
843 _par_last_obj_copy_times_ms[i] = -1234.0;
844 _par_last_termination_times_ms[i] = -1234.0;
845 _par_last_termination_attempts[i] = -1234.0;
846 _par_last_gc_worker_end_times_ms[i] = -1234.0;
847 }
848 #endif
849
850 for (int i = 0; i < _aux_num; ++i) {
851 _cur_aux_times_ms[i] = 0.0;
852 _cur_aux_times_set[i] = false;
853 }
854
855 _satb_drain_time_set = false;
856 _last_satb_drain_processed_buffers = -1;
857
858 if (in_young_gc_mode())
859 _last_young_gc_full = false;
860
861 // do that for any other surv rate groups
862 _short_lived_surv_rate_group->stop_adding_regions();
863 _survivors_age_table.clear();
864
865 assert( verify_young_ages(), "region age verification" );
866 }
867
868 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
869 _mark_closure_time_ms = mark_closure_time_ms;
870 }
871
872 void G1CollectorPolicy::record_concurrent_mark_init_start() {
873 _mark_init_start_sec = os::elapsedTime();
874 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
875 }
876
877 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
878 mark_init_elapsed_time_ms) {
879 _during_marking = true;
880 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
881 clear_during_initial_mark_pause();
882 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
883 }
884
885 void G1CollectorPolicy::record_concurrent_mark_init_end() {
886 double end_time_sec = os::elapsedTime();
887 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
888 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
889 record_concurrent_mark_init_end_pre(elapsed_time_ms);
890
891 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
892 }
893
894 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
895 _mark_remark_start_sec = os::elapsedTime();
896 _during_marking = false;
897 }
898
899 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
900 double end_time_sec = os::elapsedTime();
901 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
902 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
903 _cur_mark_stop_world_time_ms += elapsed_time_ms;
904 _prev_collection_pause_end_ms += elapsed_time_ms;
905
906 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
907 }
908
909 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
910 _mark_cleanup_start_sec = os::elapsedTime();
911 }
912
913 void
914 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
915 size_t max_live_bytes) {
916 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
917 record_concurrent_mark_cleanup_end_work2();
918 }
919
920 void
921 G1CollectorPolicy::
922 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
923 size_t max_live_bytes) {
924 if (_n_marks < 2) _n_marks++;
925 if (G1PolicyVerbose > 0)
926 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
927 " (of " SIZE_FORMAT " MB heap).",
928 max_live_bytes/M, _g1->capacity()/M);
929 }
930
931 // The important thing about this is that it includes "os::elapsedTime".
932 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
933 double end_time_sec = os::elapsedTime();
934 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
935 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
936 _cur_mark_stop_world_time_ms += elapsed_time_ms;
937 _prev_collection_pause_end_ms += elapsed_time_ms;
938
939 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
940
941 _num_markings++;
942
943 // We did a marking, so reset the "since_last_mark" variables.
944 double considerConcMarkCost = 1.0;
945 // If there are available processors, concurrent activity is free...
946 if (Threads::number_of_non_daemon_threads() * 2 <
947 os::active_processor_count()) {
948 considerConcMarkCost = 0.0;
949 }
950 _n_pauses_at_mark_end = _n_pauses;
951 _n_marks_since_last_pause++;
952 }
953
954 void
955 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
956 if (in_young_gc_mode()) {
957 _should_revert_to_full_young_gcs = false;
958 _last_full_young_gc = true;
959 _in_marking_window = false;
960 if (adaptive_young_list_length())
961 calculate_young_list_target_length();
962 }
963 }
964
965 void G1CollectorPolicy::record_concurrent_pause() {
966 if (_stop_world_start > 0.0) {
967 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
968 _all_yield_times_ms->add(yield_ms);
969 }
970 }
971
972 void G1CollectorPolicy::record_concurrent_pause_end() {
973 }
974
975 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
976 _cur_CH_strong_roots_end_sec = os::elapsedTime();
977 _cur_CH_strong_roots_dur_ms =
978 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
979 }
980
981 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
982 _cur_G1_strong_roots_end_sec = os::elapsedTime();
983 _cur_G1_strong_roots_dur_ms =
984 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
985 }
986
987 template<class T>
988 T sum_of(T* sum_arr, int start, int n, int N) {
989 T sum = (T)0;
990 for (int i = 0; i < n; i++) {
991 int j = (start + i) % N;
992 sum += sum_arr[j];
993 }
994 return sum;
995 }
996
997 void G1CollectorPolicy::print_par_stats(int level,
998 const char* str,
999 double* data,
1000 bool summary) {
1001 double min = data[0], max = data[0];
1002 double total = 0.0;
1003 int j;
1004 for (j = 0; j < level; ++j)
1005 gclog_or_tty->print(" ");
1006 gclog_or_tty->print("[%s (ms):", str);
1007 for (uint i = 0; i < ParallelGCThreads; ++i) {
1008 double val = data[i];
1009 if (val < min)
1010 min = val;
1011 if (val > max)
1012 max = val;
1013 total += val;
1014 gclog_or_tty->print(" %3.1lf", val);
1015 }
1016 if (summary) {
1017 gclog_or_tty->print_cr("");
1018 double avg = total / (double) ParallelGCThreads;
1019 gclog_or_tty->print(" ");
1020 for (j = 0; j < level; ++j)
1021 gclog_or_tty->print(" ");
1022 gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
1023 avg, min, max);
1024 }
1025 gclog_or_tty->print_cr("]");
1026 }
1027
1028 void G1CollectorPolicy::print_par_sizes(int level,
1029 const char* str,
1030 double* data,
1031 bool summary) {
1032 double min = data[0], max = data[0];
1033 double total = 0.0;
1034 int j;
1035 for (j = 0; j < level; ++j)
1036 gclog_or_tty->print(" ");
1037 gclog_or_tty->print("[%s :", str);
1038 for (uint i = 0; i < ParallelGCThreads; ++i) {
1039 double val = data[i];
1040 if (val < min)
1041 min = val;
1042 if (val > max)
1043 max = val;
1044 total += val;
1045 gclog_or_tty->print(" %d", (int) val);
1046 }
1047 if (summary) {
1048 gclog_or_tty->print_cr("");
1049 double avg = total / (double) ParallelGCThreads;
1050 gclog_or_tty->print(" ");
1051 for (j = 0; j < level; ++j)
1052 gclog_or_tty->print(" ");
1053 gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
1054 (int)total, (int)avg, (int)min, (int)max);
1055 }
1056 gclog_or_tty->print_cr("]");
1057 }
1058
1059 void G1CollectorPolicy::print_stats (int level,
1060 const char* str,
1061 double value) {
1062 for (int j = 0; j < level; ++j)
1063 gclog_or_tty->print(" ");
1064 gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
1065 }
1066
1067 void G1CollectorPolicy::print_stats (int level,
1068 const char* str,
1069 int value) {
1070 for (int j = 0; j < level; ++j)
1071 gclog_or_tty->print(" ");
1072 gclog_or_tty->print_cr("[%s: %d]", str, value);
1073 }
1074
1075 double G1CollectorPolicy::avg_value (double* data) {
1076 if (ParallelGCThreads > 0) {
1077 double ret = 0.0;
1078 for (uint i = 0; i < ParallelGCThreads; ++i)
1079 ret += data[i];
1080 return ret / (double) ParallelGCThreads;
1081 } else {
1082 return data[0];
1083 }
1084 }
1085
1086 double G1CollectorPolicy::max_value (double* data) {
1087 if (ParallelGCThreads > 0) {
1088 double ret = data[0];
1089 for (uint i = 1; i < ParallelGCThreads; ++i)
1090 if (data[i] > ret)
1091 ret = data[i];
1092 return ret;
1093 } else {
1094 return data[0];
1095 }
1096 }
1097
1098 double G1CollectorPolicy::sum_of_values (double* data) {
1099 if (ParallelGCThreads > 0) {
1100 double sum = 0.0;
1101 for (uint i = 0; i < ParallelGCThreads; i++)
1102 sum += data[i];
1103 return sum;
1104 } else {
1105 return data[0];
1106 }
1107 }
1108
1109 double G1CollectorPolicy::max_sum (double* data1,
1110 double* data2) {
1111 double ret = data1[0] + data2[0];
1112
1113 if (ParallelGCThreads > 0) {
1114 for (uint i = 1; i < ParallelGCThreads; ++i) {
1115 double data = data1[i] + data2[i];
1116 if (data > ret)
1117 ret = data;
1118 }
1119 }
1120 return ret;
1121 }
1122
1123 // Anything below that is considered to be zero
1124 #define MIN_TIMER_GRANULARITY 0.0000001
1125
1126 void G1CollectorPolicy::record_collection_pause_end() {
1127 double end_time_sec = os::elapsedTime();
1128 double elapsed_ms = _last_pause_time_ms;
1129 bool parallel = ParallelGCThreads > 0;
1130 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1131 size_t rs_size =
1132 _cur_collection_pause_used_regions_at_start - collection_set_size();
1133 size_t cur_used_bytes = _g1->used();
1134 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1135 bool last_pause_included_initial_mark = false;
1136 bool update_stats = !_g1->evacuation_failed();
1137
1138 #ifndef PRODUCT
1139 if (G1YoungSurvRateVerbose) {
1140 gclog_or_tty->print_cr("");
1141 _short_lived_surv_rate_group->print();
1142 // do that for any other surv rate groups too
1143 }
1144 #endif // PRODUCT
1145
1146 if (in_young_gc_mode()) {
1147 last_pause_included_initial_mark = during_initial_mark_pause();
1148 if (last_pause_included_initial_mark)
1149 record_concurrent_mark_init_end_pre(0.0);
1150
1151 size_t min_used_targ =
1152 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1153
1154
1155 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1156 assert(!last_pause_included_initial_mark, "invariant");
1157 if (cur_used_bytes > min_used_targ &&
1158 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1159 assert(!during_initial_mark_pause(), "we should not see this here");
1160
1161 // Note: this might have already been set, if during the last
1162 // pause we decided to start a cycle but at the beginning of
1163 // this pause we decided to postpone it. That's OK.
1164 set_initiate_conc_mark_if_possible();
1165 }
1166 }
1167
1168 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1169 }
1170
1171 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1172 end_time_sec, false);
1173
1174 guarantee(_cur_collection_pause_used_regions_at_start >=
1175 collection_set_size(),
1176 "Negative RS size?");
1177
1178 // This assert is exempted when we're doing parallel collection pauses,
1179 // because the fragmentation caused by the parallel GC allocation buffers
1180 // can lead to more memory being used during collection than was used
1181 // before. Best leave this out until the fragmentation problem is fixed.
1182 // Pauses in which evacuation failed can also lead to negative
1183 // collections, since no space is reclaimed from a region containing an
1184 // object whose evacuation failed.
1185 // Further, we're now always doing parallel collection. But I'm still
1186 // leaving this here as a placeholder for a more precise assertion later.
1187 // (DLD, 10/05.)
1188 assert((true || parallel) // Always using GC LABs now.
1189 || _g1->evacuation_failed()
1190 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1191 "Negative collection");
1192
1193 size_t freed_bytes =
1194 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1195 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1196
1197 double survival_fraction =
1198 (double)surviving_bytes/
1199 (double)_collection_set_bytes_used_before;
1200
1201 _n_pauses++;
1202
1203 if (update_stats) {
1204 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1205 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1206 _recent_evac_times_ms->add(evac_ms);
1207 _recent_pause_times_ms->add(elapsed_ms);
1208
1209 _recent_rs_sizes->add(rs_size);
1210
1211 // We exempt parallel collection from this check because Alloc Buffer
1212 // fragmentation can produce negative collections. Same with evac
1213 // failure.
1214 // Further, we're now always doing parallel collection. But I'm still
1215 // leaving this here as a placeholder for a more precise assertion later.
1216 // (DLD, 10/05.
1217 assert((true || parallel)
1218 || _g1->evacuation_failed()
1219 || surviving_bytes <= _collection_set_bytes_used_before,
1220 "Or else negative collection!");
1221 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1222 _recent_CS_bytes_surviving->add(surviving_bytes);
1223
1224 // this is where we update the allocation rate of the application
1225 double app_time_ms =
1226 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1227 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1228 // This usually happens due to the timer not having the required
1229 // granularity. Some Linuxes are the usual culprits.
1230 // We'll just set it to something (arbitrarily) small.
1231 app_time_ms = 1.0;
1232 }
1233 size_t regions_allocated =
1234 (_region_num_young - _prev_region_num_young) +
1235 (_region_num_tenured - _prev_region_num_tenured);
1236 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1237 _alloc_rate_ms_seq->add(alloc_rate_ms);
1238 _prev_region_num_young = _region_num_young;
1239 _prev_region_num_tenured = _region_num_tenured;
1240
1241 double interval_ms =
1242 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1243 update_recent_gc_times(end_time_sec, elapsed_ms);
1244 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1245 if (recent_avg_pause_time_ratio() < 0.0 ||
1246 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1247 #ifndef PRODUCT
1248 // Dump info to allow post-facto debugging
1249 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1250 gclog_or_tty->print_cr("-------------------------------------------");
1251 gclog_or_tty->print_cr("Recent GC Times (ms):");
1252 _recent_gc_times_ms->dump();
1253 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1254 _recent_prev_end_times_for_all_gcs_sec->dump();
1255 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1256 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1257 // In debug mode, terminate the JVM if the user wants to debug at this point.
1258 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1259 #endif // !PRODUCT
1260 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1261 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1262 if (_recent_avg_pause_time_ratio < 0.0) {
1263 _recent_avg_pause_time_ratio = 0.0;
1264 } else {
1265 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1266 _recent_avg_pause_time_ratio = 1.0;
1267 }
1268 }
1269 }
1270
1271 if (G1PolicyVerbose > 1) {
1272 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1273 }
1274
1275 PauseSummary* summary = _summary;
1276
1277 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1278 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1279 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1280 double update_rs_processed_buffers =
1281 sum_of_values(_par_last_update_rs_processed_buffers);
1282 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1283 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1284 double termination_time = avg_value(_par_last_termination_times_ms);
1285
1286 double parallel_other_time = _cur_collection_par_time_ms -
1287 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1288 scan_rs_time + obj_copy_time + termination_time);
1289 if (update_stats) {
1290 MainBodySummary* body_summary = summary->main_body_summary();
1291 guarantee(body_summary != NULL, "should not be null!");
1292
1293 if (_satb_drain_time_set)
1294 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1295 else
1296 body_summary->record_satb_drain_time_ms(0.0);
1297 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1298 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1299 body_summary->record_update_rs_time_ms(update_rs_time);
1300 body_summary->record_scan_rs_time_ms(scan_rs_time);
1301 body_summary->record_obj_copy_time_ms(obj_copy_time);
1302 if (parallel) {
1303 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1304 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1305 body_summary->record_termination_time_ms(termination_time);
1306 body_summary->record_parallel_other_time_ms(parallel_other_time);
1307 }
1308 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1309 }
1310
1311 if (G1PolicyVerbose > 1) {
1312 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1313 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1314 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1315 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1316 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1317 " |RS|: " SIZE_FORMAT,
1318 elapsed_ms, recent_avg_time_for_pauses_ms(),
1319 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1320 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1321 evac_ms, recent_avg_time_for_evac_ms(),
1322 scan_rs_time,
1323 recent_avg_time_for_pauses_ms() -
1324 recent_avg_time_for_G1_strong_ms(),
1325 rs_size);
1326
1327 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1328 " At end " SIZE_FORMAT "K\n"
1329 " garbage : " SIZE_FORMAT "K"
1330 " of " SIZE_FORMAT "K\n"
1331 " survival : %6.2f%% (%6.2f%% avg)",
1332 _cur_collection_pause_used_at_start_bytes/K,
1333 _g1->used()/K, freed_bytes/K,
1334 _collection_set_bytes_used_before/K,
1335 survival_fraction*100.0,
1336 recent_avg_survival_fraction()*100.0);
1337 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1338 recent_avg_pause_time_ratio() * 100.0);
1339 }
1340
1341 double other_time_ms = elapsed_ms;
1342
1343 if (_satb_drain_time_set) {
1344 other_time_ms -= _cur_satb_drain_time_ms;
1345 }
1346
1347 if (parallel) {
1348 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1349 } else {
1350 other_time_ms -=
1351 update_rs_time +
1352 ext_root_scan_time + mark_stack_scan_time +
1353 scan_rs_time + obj_copy_time;
1354 }
1355
1356 if (PrintGCDetails) {
1357 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1358 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1359 elapsed_ms / 1000.0);
1360
1361 if (_satb_drain_time_set) {
1362 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1363 }
1364 if (_last_satb_drain_processed_buffers >= 0) {
1365 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1366 }
1367 if (parallel) {
1368 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1369 print_par_stats(2, "GC Worker Start Time",
1370 _par_last_gc_worker_start_times_ms, false);
1371 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1372 print_par_sizes(3, "Processed Buffers",
1373 _par_last_update_rs_processed_buffers, true);
1374 print_par_stats(2, "Ext Root Scanning",
1375 _par_last_ext_root_scan_times_ms);
1376 print_par_stats(2, "Mark Stack Scanning",
1377 _par_last_mark_stack_scan_times_ms);
1378 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1379 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1380 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1381 print_par_sizes(3, "Termination Attempts",
1382 _par_last_termination_attempts, true);
1383 print_par_stats(2, "GC Worker End Time",
1384 _par_last_gc_worker_end_times_ms, false);
1385 print_stats(2, "Other", parallel_other_time);
1386 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1387 } else {
1388 print_stats(1, "Update RS", update_rs_time);
1389 print_stats(2, "Processed Buffers",
1390 (int)update_rs_processed_buffers);
1391 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1392 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1393 print_stats(1, "Scan RS", scan_rs_time);
1394 print_stats(1, "Object Copying", obj_copy_time);
1395 }
1396 #ifndef PRODUCT
1397 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1398 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1399 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1400 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1401 if (_num_cc_clears > 0) {
1402 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1403 }
1404 #endif
1405 print_stats(1, "Other", other_time_ms);
1406 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1407
1408 for (int i = 0; i < _aux_num; ++i) {
1409 if (_cur_aux_times_set[i]) {
1410 char buffer[96];
1411 sprintf(buffer, "Aux%d", i);
1412 print_stats(1, buffer, _cur_aux_times_ms[i]);
1413 }
1414 }
1415 }
1416 if (PrintGCDetails)
1417 gclog_or_tty->print(" [");
1418 if (PrintGC || PrintGCDetails)
1419 _g1->print_size_transition(gclog_or_tty,
1420 _cur_collection_pause_used_at_start_bytes,
1421 _g1->used(), _g1->capacity());
1422 if (PrintGCDetails)
1423 gclog_or_tty->print_cr("]");
1424
1425 _all_pause_times_ms->add(elapsed_ms);
1426 if (update_stats) {
1427 summary->record_total_time_ms(elapsed_ms);
1428 summary->record_other_time_ms(other_time_ms);
1429 }
1430 for (int i = 0; i < _aux_num; ++i)
1431 if (_cur_aux_times_set[i])
1432 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1433
1434 // Reset marks-between-pauses counter.
1435 _n_marks_since_last_pause = 0;
1436
1437 // Update the efficiency-since-mark vars.
1438 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1439 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1440 // This usually happens due to the timer not having the required
1441 // granularity. Some Linuxes are the usual culprits.
1442 // We'll just set it to something (arbitrarily) small.
1443 proc_ms = 1.0;
1444 }
1445 double cur_efficiency = (double) freed_bytes / proc_ms;
1446
1447 bool new_in_marking_window = _in_marking_window;
1448 bool new_in_marking_window_im = false;
1449 if (during_initial_mark_pause()) {
1450 new_in_marking_window = true;
1451 new_in_marking_window_im = true;
1452 }
1453
1454 if (in_young_gc_mode()) {
1455 if (_last_full_young_gc) {
1456 set_full_young_gcs(false);
1457 _last_full_young_gc = false;
1458 }
1459
1460 if ( !_last_young_gc_full ) {
1461 if ( _should_revert_to_full_young_gcs ||
1462 _known_garbage_ratio < 0.05 ||
1463 (adaptive_young_list_length() &&
1464 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1465 set_full_young_gcs(true);
1466 }
1467 }
1468 _should_revert_to_full_young_gcs = false;
1469
1470 if (_last_young_gc_full && !_during_marking)
1471 _young_gc_eff_seq->add(cur_efficiency);
1472 }
1473
1474 _short_lived_surv_rate_group->start_adding_regions();
1475 // do that for any other surv rate groupsx
1476
1477 // <NEW PREDICTION>
1478
1479 if (update_stats) {
1480 double pause_time_ms = elapsed_ms;
1481
1482 size_t diff = 0;
1483 if (_max_pending_cards >= _pending_cards)
1484 diff = _max_pending_cards - _pending_cards;
1485 _pending_card_diff_seq->add((double) diff);
1486
1487 double cost_per_card_ms = 0.0;
1488 if (_pending_cards > 0) {
1489 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1490 _cost_per_card_ms_seq->add(cost_per_card_ms);
1491 }
1492
1493 size_t cards_scanned = _g1->cards_scanned();
1494
1495 double cost_per_entry_ms = 0.0;
1496 if (cards_scanned > 10) {
1497 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1498 if (_last_young_gc_full)
1499 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1500 else
1501 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1502 }
1503
1504 if (_max_rs_lengths > 0) {
1505 double cards_per_entry_ratio =
1506 (double) cards_scanned / (double) _max_rs_lengths;
1507 if (_last_young_gc_full)
1508 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1509 else
1510 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1511 }
1512
1513 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1514 if (rs_length_diff >= 0)
1515 _rs_length_diff_seq->add((double) rs_length_diff);
1516
1517 size_t copied_bytes = surviving_bytes;
1518 double cost_per_byte_ms = 0.0;
1519 if (copied_bytes > 0) {
1520 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1521 if (_in_marking_window)
1522 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1523 else
1524 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1525 }
1526
1527 double all_other_time_ms = pause_time_ms -
1528 (update_rs_time + scan_rs_time + obj_copy_time +
1529 _mark_closure_time_ms + termination_time);
1530
1531 double young_other_time_ms = 0.0;
1532 if (_recorded_young_regions > 0) {
1533 young_other_time_ms =
1534 _recorded_young_cset_choice_time_ms +
1535 _recorded_young_free_cset_time_ms;
1536 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1537 (double) _recorded_young_regions);
1538 }
1539 double non_young_other_time_ms = 0.0;
1540 if (_recorded_non_young_regions > 0) {
1541 non_young_other_time_ms =
1542 _recorded_non_young_cset_choice_time_ms +
1543 _recorded_non_young_free_cset_time_ms;
1544
1545 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1546 (double) _recorded_non_young_regions);
1547 }
1548
1549 double constant_other_time_ms = all_other_time_ms -
1550 (young_other_time_ms + non_young_other_time_ms);
1551 _constant_other_time_ms_seq->add(constant_other_time_ms);
1552
1553 double survival_ratio = 0.0;
1554 if (_bytes_in_collection_set_before_gc > 0) {
1555 survival_ratio = (double) bytes_in_to_space_during_gc() /
1556 (double) _bytes_in_collection_set_before_gc;
1557 }
1558
1559 _pending_cards_seq->add((double) _pending_cards);
1560 _scanned_cards_seq->add((double) cards_scanned);
1561 _rs_lengths_seq->add((double) _max_rs_lengths);
1562
1563 double expensive_region_limit_ms =
1564 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1565 if (expensive_region_limit_ms < 0.0) {
1566 // this means that the other time was predicted to be longer than
1567 // than the max pause time
1568 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1569 }
1570 _expensive_region_limit_ms = expensive_region_limit_ms;
1571
1572 if (PREDICTIONS_VERBOSE) {
1573 gclog_or_tty->print_cr("");
1574 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1575 "REGIONS %d %d %d "
1576 "PENDING_CARDS %d %d "
1577 "CARDS_SCANNED %d %d "
1578 "RS_LENGTHS %d %d "
1579 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1580 "SURVIVAL_RATIO %1.6lf %1.6lf "
1581 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1582 "OTHER_YOUNG %1.6lf %1.6lf "
1583 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1584 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1585 "ELAPSED %1.6lf %1.6lf ",
1586 _cur_collection_start_sec,
1587 (!_last_young_gc_full) ? 2 :
1588 (last_pause_included_initial_mark) ? 1 : 0,
1589 _recorded_region_num,
1590 _recorded_young_regions,
1591 _recorded_non_young_regions,
1592 _predicted_pending_cards, _pending_cards,
1593 _predicted_cards_scanned, cards_scanned,
1594 _predicted_rs_lengths, _max_rs_lengths,
1595 _predicted_rs_update_time_ms, update_rs_time,
1596 _predicted_rs_scan_time_ms, scan_rs_time,
1597 _predicted_survival_ratio, survival_ratio,
1598 _predicted_object_copy_time_ms, obj_copy_time,
1599 _predicted_constant_other_time_ms, constant_other_time_ms,
1600 _predicted_young_other_time_ms, young_other_time_ms,
1601 _predicted_non_young_other_time_ms,
1602 non_young_other_time_ms,
1603 _vtime_diff_ms, termination_time,
1604 _predicted_pause_time_ms, elapsed_ms);
1605 }
1606
1607 if (G1PolicyVerbose > 0) {
1608 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1609 _predicted_pause_time_ms,
1610 (_within_target) ? "within" : "outside",
1611 elapsed_ms);
1612 }
1613
1614 }
1615
1616 _in_marking_window = new_in_marking_window;
1617 _in_marking_window_im = new_in_marking_window_im;
1618 _free_regions_at_end_of_collection = _g1->free_regions();
1619 calculate_young_list_min_length();
1620 calculate_young_list_target_length();
1621
1622 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1623 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1624 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1625 // </NEW PREDICTION>
1626 }
1627
1628 // <NEW PREDICTION>
1629
1630 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1631 double update_rs_processed_buffers,
1632 double goal_ms) {
1633 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1634 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1635
1636 if (G1UseAdaptiveConcRefinement) {
1637 const int k_gy = 3, k_gr = 6;
1638 const double inc_k = 1.1, dec_k = 0.9;
1639
1640 int g = cg1r->green_zone();
1641 if (update_rs_time > goal_ms) {
1642 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1643 } else {
1644 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1645 g = (int)MAX2(g * inc_k, g + 1.0);
1646 }
1647 }
1648 // Change the refinement threads params
1649 cg1r->set_green_zone(g);
1650 cg1r->set_yellow_zone(g * k_gy);
1651 cg1r->set_red_zone(g * k_gr);
1652 cg1r->reinitialize_threads();
1653
1654 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1655 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1656 cg1r->yellow_zone());
1657 // Change the barrier params
1658 dcqs.set_process_completed_threshold(processing_threshold);
1659 dcqs.set_max_completed_queue(cg1r->red_zone());
1660 }
1661
1662 int curr_queue_size = dcqs.completed_buffers_num();
1663 if (curr_queue_size >= cg1r->yellow_zone()) {
1664 dcqs.set_completed_queue_padding(curr_queue_size);
1665 } else {
1666 dcqs.set_completed_queue_padding(0);
1667 }
1668 dcqs.notify_if_necessary();
1669 }
1670
1671 double
1672 G1CollectorPolicy::
1673 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1674 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1675
1676 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1677 size_t young_num = g1h->young_list()->length();
1678 if (young_num == 0)
1679 return 0.0;
1680
1681 young_num += adjustment;
1682 size_t pending_cards = predict_pending_cards();
1683 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1684 predict_rs_length_diff();
1685 size_t card_num;
1686 if (full_young_gcs())
1687 card_num = predict_young_card_num(rs_lengths);
1688 else
1689 card_num = predict_non_young_card_num(rs_lengths);
1690 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1691 double accum_yg_surv_rate =
1692 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1693
1694 size_t bytes_to_copy =
1695 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1696
1697 return
1698 predict_rs_update_time_ms(pending_cards) +
1699 predict_rs_scan_time_ms(card_num) +
1700 predict_object_copy_time_ms(bytes_to_copy) +
1701 predict_young_other_time_ms(young_num) +
1702 predict_constant_other_time_ms();
1703 }
1704
1705 double
1706 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1707 size_t rs_length = predict_rs_length_diff();
1708 size_t card_num;
1709 if (full_young_gcs())
1710 card_num = predict_young_card_num(rs_length);
1711 else
1712 card_num = predict_non_young_card_num(rs_length);
1713 return predict_base_elapsed_time_ms(pending_cards, card_num);
1714 }
1715
1716 double
1717 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1718 size_t scanned_cards) {
1719 return
1720 predict_rs_update_time_ms(pending_cards) +
1721 predict_rs_scan_time_ms(scanned_cards) +
1722 predict_constant_other_time_ms();
1723 }
1724
1725 double
1726 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1727 bool young) {
1728 size_t rs_length = hr->rem_set()->occupied();
1729 size_t card_num;
1730 if (full_young_gcs())
1731 card_num = predict_young_card_num(rs_length);
1732 else
1733 card_num = predict_non_young_card_num(rs_length);
1734 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1735
1736 double region_elapsed_time_ms =
1737 predict_rs_scan_time_ms(card_num) +
1738 predict_object_copy_time_ms(bytes_to_copy);
1739
1740 if (young)
1741 region_elapsed_time_ms += predict_young_other_time_ms(1);
1742 else
1743 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1744
1745 return region_elapsed_time_ms;
1746 }
1747
1748 size_t
1749 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1750 size_t bytes_to_copy;
1751 if (hr->is_marked())
1752 bytes_to_copy = hr->max_live_bytes();
1753 else {
1754 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1755 "invariant" );
1756 int age = hr->age_in_surv_rate_group();
1757 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1758 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1759 }
1760
1761 return bytes_to_copy;
1762 }
1763
1764 void
1765 G1CollectorPolicy::start_recording_regions() {
1766 _recorded_rs_lengths = 0;
1767 _recorded_young_regions = 0;
1768 _recorded_non_young_regions = 0;
1769
1770 #if PREDICTIONS_VERBOSE
1771 _recorded_marked_bytes = 0;
1772 _recorded_young_bytes = 0;
1773 _predicted_bytes_to_copy = 0;
1774 _predicted_rs_lengths = 0;
1775 _predicted_cards_scanned = 0;
1776 #endif // PREDICTIONS_VERBOSE
1777 }
1778
1779 void
1780 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1781 #if PREDICTIONS_VERBOSE
1782 if (!young) {
1783 _recorded_marked_bytes += hr->max_live_bytes();
1784 }
1785 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1786 #endif // PREDICTIONS_VERBOSE
1787
1788 size_t rs_length = hr->rem_set()->occupied();
1789 _recorded_rs_lengths += rs_length;
1790 }
1791
1792 void
1793 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1794 assert(!hr->is_young(), "should not call this");
1795 ++_recorded_non_young_regions;
1796 record_cset_region_info(hr, false);
1797 }
1798
1799 void
1800 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1801 _recorded_young_regions = n_regions;
1802 }
1803
1804 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1805 #if PREDICTIONS_VERBOSE
1806 _recorded_young_bytes = bytes;
1807 #endif // PREDICTIONS_VERBOSE
1808 }
1809
1810 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1811 _recorded_rs_lengths = rs_lengths;
1812 }
1813
1814 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1815 _predicted_bytes_to_copy = bytes;
1816 }
1817
1818 void
1819 G1CollectorPolicy::end_recording_regions() {
1820 // The _predicted_pause_time_ms field is referenced in code
1821 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1822 _predicted_pause_time_ms = -1.0;
1823
1824 #if PREDICTIONS_VERBOSE
1825 _predicted_pending_cards = predict_pending_cards();
1826 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1827 if (full_young_gcs())
1828 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1829 else
1830 _predicted_cards_scanned +=
1831 predict_non_young_card_num(_predicted_rs_lengths);
1832 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1833
1834 _predicted_rs_update_time_ms =
1835 predict_rs_update_time_ms(_g1->pending_card_num());
1836 _predicted_rs_scan_time_ms =
1837 predict_rs_scan_time_ms(_predicted_cards_scanned);
1838 _predicted_object_copy_time_ms =
1839 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1840 _predicted_constant_other_time_ms =
1841 predict_constant_other_time_ms();
1842 _predicted_young_other_time_ms =
1843 predict_young_other_time_ms(_recorded_young_regions);
1844 _predicted_non_young_other_time_ms =
1845 predict_non_young_other_time_ms(_recorded_non_young_regions);
1846
1847 _predicted_pause_time_ms =
1848 _predicted_rs_update_time_ms +
1849 _predicted_rs_scan_time_ms +
1850 _predicted_object_copy_time_ms +
1851 _predicted_constant_other_time_ms +
1852 _predicted_young_other_time_ms +
1853 _predicted_non_young_other_time_ms;
1854 #endif // PREDICTIONS_VERBOSE
1855 }
1856
1857 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1858 predicted_time_ms) {
1859 // I don't think we need to do this when in young GC mode since
1860 // marking will be initiated next time we hit the soft limit anyway...
1861 if (predicted_time_ms > _expensive_region_limit_ms) {
1862 if (!in_young_gc_mode()) {
1863 set_full_young_gcs(true);
1864 // We might want to do something different here. However,
1865 // right now we don't support the non-generational G1 mode
1866 // (and in fact we are planning to remove the associated code,
1867 // see CR 6814390). So, let's leave it as is and this will be
1868 // removed some time in the future
1869 ShouldNotReachHere();
1870 set_during_initial_mark_pause();
1871 } else
1872 // no point in doing another partial one
1873 _should_revert_to_full_young_gcs = true;
1874 }
1875 }
1876
1877 // </NEW PREDICTION>
1878
1879
1880 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1881 double elapsed_ms) {
1882 _recent_gc_times_ms->add(elapsed_ms);
1883 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1884 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1885 }
1886
1887 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1888 if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
1889 else return _recent_pause_times_ms->avg();
1890 }
1891
1892 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
1893 if (_recent_CH_strong_roots_times_ms->num() == 0)
1894 return (double)MaxGCPauseMillis/3.0;
1895 else return _recent_CH_strong_roots_times_ms->avg();
1896 }
1897
1898 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
1899 if (_recent_G1_strong_roots_times_ms->num() == 0)
1900 return (double)MaxGCPauseMillis/3.0;
1901 else return _recent_G1_strong_roots_times_ms->avg();
1902 }
1903
1904 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
1905 if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
1906 else return _recent_evac_times_ms->avg();
1907 }
1908
1909 int G1CollectorPolicy::number_of_recent_gcs() {
1910 assert(_recent_CH_strong_roots_times_ms->num() ==
1911 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
1912 assert(_recent_G1_strong_roots_times_ms->num() ==
1913 _recent_evac_times_ms->num(), "Sequence out of sync");
1914 assert(_recent_evac_times_ms->num() ==
1915 _recent_pause_times_ms->num(), "Sequence out of sync");
1916 assert(_recent_pause_times_ms->num() ==
1917 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1918 assert(_recent_CS_bytes_used_before->num() ==
1919 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1920 return _recent_pause_times_ms->num();
1921 }
1922
1923 double G1CollectorPolicy::recent_avg_survival_fraction() {
1924 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1925 _recent_CS_bytes_used_before);
1926 }
1927
1928 double G1CollectorPolicy::last_survival_fraction() {
1929 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1930 _recent_CS_bytes_used_before);
1931 }
1932
1933 double
1934 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1935 TruncatedSeq* before) {
1936 assert(surviving->num() == before->num(), "Sequence out of sync");
1937 if (before->sum() > 0.0) {
1938 double recent_survival_rate = surviving->sum() / before->sum();
1939 // We exempt parallel collection from this check because Alloc Buffer
1940 // fragmentation can produce negative collections.
1941 // Further, we're now always doing parallel collection. But I'm still
1942 // leaving this here as a placeholder for a more precise assertion later.
1943 // (DLD, 10/05.)
1944 assert((true || ParallelGCThreads > 0) ||
1945 _g1->evacuation_failed() ||
1946 recent_survival_rate <= 1.0, "Or bad frac");
1947 return recent_survival_rate;
1948 } else {
1949 return 1.0; // Be conservative.
1950 }
1951 }
1952
1953 double
1954 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
1955 TruncatedSeq* before) {
1956 assert(surviving->num() == before->num(), "Sequence out of sync");
1957 if (surviving->num() > 0 && before->last() > 0.0) {
1958 double last_survival_rate = surviving->last() / before->last();
1959 // We exempt parallel collection from this check because Alloc Buffer
1960 // fragmentation can produce negative collections.
1961 // Further, we're now always doing parallel collection. But I'm still
1962 // leaving this here as a placeholder for a more precise assertion later.
1963 // (DLD, 10/05.)
1964 assert((true || ParallelGCThreads > 0) ||
1965 last_survival_rate <= 1.0, "Or bad frac");
1966 return last_survival_rate;
1967 } else {
1968 return 1.0;
1969 }
1970 }
1971
1972 static const int survival_min_obs = 5;
1973 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
1974 static const double min_survival_rate = 0.1;
1975
1976 double
1977 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
1978 double latest) {
1979 double res = avg;
1980 if (number_of_recent_gcs() < survival_min_obs) {
1981 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
1982 }
1983 res = MAX2(res, latest);
1984 res = MAX2(res, min_survival_rate);
1985 // In the parallel case, LAB fragmentation can produce "negative
1986 // collections"; so can evac failure. Cap at 1.0
1987 res = MIN2(res, 1.0);
1988 return res;
1989 }
1990
1991 size_t G1CollectorPolicy::expansion_amount() {
1992 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
1993 // We will double the existing space, or take
1994 // G1ExpandByPercentOfAvailable % of the available expansion
1995 // space, whichever is smaller, bounded below by a minimum
1996 // expansion (unless that's all that's left.)
1997 const size_t min_expand_bytes = 1*M;
1998 size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
1999 size_t committed_bytes = _g1->capacity();
2000 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2001 size_t expand_bytes;
2002 size_t expand_bytes_via_pct =
2003 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2004 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2005 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2006 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2007 if (G1PolicyVerbose > 1) {
2008 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2009 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2010 " Answer = %d.\n",
2011 recent_avg_pause_time_ratio(),
2012 byte_size_in_proper_unit(committed_bytes),
2013 proper_unit_for_byte_size(committed_bytes),
2014 byte_size_in_proper_unit(uncommitted_bytes),
2015 proper_unit_for_byte_size(uncommitted_bytes),
2016 byte_size_in_proper_unit(expand_bytes_via_pct),
2017 proper_unit_for_byte_size(expand_bytes_via_pct),
2018 byte_size_in_proper_unit(expand_bytes),
2019 proper_unit_for_byte_size(expand_bytes));
2020 }
2021 return expand_bytes;
2022 } else {
2023 return 0;
2024 }
2025 }
2026
2027 void G1CollectorPolicy::note_start_of_mark_thread() {
2028 _mark_thread_startup_sec = os::elapsedTime();
2029 }
2030
2031 class CountCSClosure: public HeapRegionClosure {
2032 G1CollectorPolicy* _g1_policy;
2033 public:
2034 CountCSClosure(G1CollectorPolicy* g1_policy) :
2035 _g1_policy(g1_policy) {}
2036 bool doHeapRegion(HeapRegion* r) {
2037 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2038 return false;
2039 }
2040 };
2041
2042 void G1CollectorPolicy::count_CS_bytes_used() {
2043 CountCSClosure cs_closure(this);
2044 _g1->collection_set_iterate(&cs_closure);
2045 }
2046
2047 static void print_indent(int level) {
2048 for (int j = 0; j < level+1; ++j)
2049 gclog_or_tty->print(" ");
2050 }
2051
2052 void G1CollectorPolicy::print_summary (int level,
2053 const char* str,
2054 NumberSeq* seq) const {
2055 double sum = seq->sum();
2056 print_indent(level);
2057 gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2058 str, sum / 1000.0, seq->avg());
2059 }
2060
2061 void G1CollectorPolicy::print_summary_sd (int level,
2062 const char* str,
2063 NumberSeq* seq) const {
2064 print_summary(level, str, seq);
2065 print_indent(level + 5);
2066 gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2067 seq->num(), seq->sd(), seq->maximum());
2068 }
2069
2070 void G1CollectorPolicy::check_other_times(int level,
2071 NumberSeq* other_times_ms,
2072 NumberSeq* calc_other_times_ms) const {
2073 bool should_print = false;
2074
2075 double max_sum = MAX2(fabs(other_times_ms->sum()),
2076 fabs(calc_other_times_ms->sum()));
2077 double min_sum = MIN2(fabs(other_times_ms->sum()),
2078 fabs(calc_other_times_ms->sum()));
2079 double sum_ratio = max_sum / min_sum;
2080 if (sum_ratio > 1.1) {
2081 should_print = true;
2082 print_indent(level + 1);
2083 gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2084 }
2085
2086 double max_avg = MAX2(fabs(other_times_ms->avg()),
2087 fabs(calc_other_times_ms->avg()));
2088 double min_avg = MIN2(fabs(other_times_ms->avg()),
2089 fabs(calc_other_times_ms->avg()));
2090 double avg_ratio = max_avg / min_avg;
2091 if (avg_ratio > 1.1) {
2092 should_print = true;
2093 print_indent(level + 1);
2094 gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2095 }
2096
2097 if (other_times_ms->sum() < -0.01) {
2098 print_indent(level + 1);
2099 gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2100 }
2101
2102 if (other_times_ms->avg() < -0.01) {
2103 print_indent(level + 1);
2104 gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2105 }
2106
2107 if (calc_other_times_ms->sum() < -0.01) {
2108 should_print = true;
2109 print_indent(level + 1);
2110 gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2111 }
2112
2113 if (calc_other_times_ms->avg() < -0.01) {
2114 should_print = true;
2115 print_indent(level + 1);
2116 gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2117 }
2118
2119 if (should_print)
2120 print_summary(level, "Other(Calc)", calc_other_times_ms);
2121 }
2122
2123 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2124 bool parallel = ParallelGCThreads > 0;
2125 MainBodySummary* body_summary = summary->main_body_summary();
2126 if (summary->get_total_seq()->num() > 0) {
2127 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2128 if (body_summary != NULL) {
2129 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2130 if (parallel) {
2131 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2132 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2133 print_summary(2, "Ext Root Scanning",
2134 body_summary->get_ext_root_scan_seq());
2135 print_summary(2, "Mark Stack Scanning",
2136 body_summary->get_mark_stack_scan_seq());
2137 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2138 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2139 print_summary(2, "Termination", body_summary->get_termination_seq());
2140 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2141 {
2142 NumberSeq* other_parts[] = {
2143 body_summary->get_update_rs_seq(),
2144 body_summary->get_ext_root_scan_seq(),
2145 body_summary->get_mark_stack_scan_seq(),
2146 body_summary->get_scan_rs_seq(),
2147 body_summary->get_obj_copy_seq(),
2148 body_summary->get_termination_seq()
2149 };
2150 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2151 6, other_parts);
2152 check_other_times(2, body_summary->get_parallel_other_seq(),
2153 &calc_other_times_ms);
2154 }
2155 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2156 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2157 } else {
2158 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2159 print_summary(1, "Ext Root Scanning",
2160 body_summary->get_ext_root_scan_seq());
2161 print_summary(1, "Mark Stack Scanning",
2162 body_summary->get_mark_stack_scan_seq());
2163 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2164 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2165 }
2166 }
2167 print_summary(1, "Other", summary->get_other_seq());
2168 {
2169 if (body_summary != NULL) {
2170 NumberSeq calc_other_times_ms;
2171 if (parallel) {
2172 // parallel
2173 NumberSeq* other_parts[] = {
2174 body_summary->get_satb_drain_seq(),
2175 body_summary->get_parallel_seq(),
2176 body_summary->get_clear_ct_seq()
2177 };
2178 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2179 3, other_parts);
2180 } else {
2181 // serial
2182 NumberSeq* other_parts[] = {
2183 body_summary->get_satb_drain_seq(),
2184 body_summary->get_update_rs_seq(),
2185 body_summary->get_ext_root_scan_seq(),
2186 body_summary->get_mark_stack_scan_seq(),
2187 body_summary->get_scan_rs_seq(),
2188 body_summary->get_obj_copy_seq()
2189 };
2190 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2191 6, other_parts);
2192 }
2193 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2194 }
2195 }
2196 } else {
2197 print_indent(0);
2198 gclog_or_tty->print_cr("none");
2199 }
2200 gclog_or_tty->print_cr("");
2201 }
2202
2203 void G1CollectorPolicy::print_tracing_info() const {
2204 if (TraceGen0Time) {
2205 gclog_or_tty->print_cr("ALL PAUSES");
2206 print_summary_sd(0, "Total", _all_pause_times_ms);
2207 gclog_or_tty->print_cr("");
2208 gclog_or_tty->print_cr("");
2209 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2210 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2211 gclog_or_tty->print_cr("");
2212
2213 gclog_or_tty->print_cr("EVACUATION PAUSES");
2214 print_summary(_summary);
2215
2216 gclog_or_tty->print_cr("MISC");
2217 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2218 print_summary_sd(0, "Yields", _all_yield_times_ms);
2219 for (int i = 0; i < _aux_num; ++i) {
2220 if (_all_aux_times_ms[i].num() > 0) {
2221 char buffer[96];
2222 sprintf(buffer, "Aux%d", i);
2223 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2224 }
2225 }
2226
2227 size_t all_region_num = _region_num_young + _region_num_tenured;
2228 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2229 "Tenured %8d (%6.2lf%%)",
2230 all_region_num,
2231 _region_num_young,
2232 (double) _region_num_young / (double) all_region_num * 100.0,
2233 _region_num_tenured,
2234 (double) _region_num_tenured / (double) all_region_num * 100.0);
2235 }
2236 if (TraceGen1Time) {
2237 if (_all_full_gc_times_ms->num() > 0) {
2238 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2239 _all_full_gc_times_ms->num(),
2240 _all_full_gc_times_ms->sum() / 1000.0);
2241 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2242 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2243 _all_full_gc_times_ms->sd(),
2244 _all_full_gc_times_ms->maximum());
2245 }
2246 }
2247 }
2248
2249 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2250 #ifndef PRODUCT
2251 _short_lived_surv_rate_group->print_surv_rate_summary();
2252 // add this call for any other surv rate groups
2253 #endif // PRODUCT
2254 }
2255
2256 bool
2257 G1CollectorPolicy::should_add_next_region_to_young_list() {
2258 assert(in_young_gc_mode(), "should be in young GC mode");
2259 bool ret;
2260 size_t young_list_length = _g1->young_list()->length();
2261 size_t young_list_max_length = _young_list_target_length;
2262 if (G1FixedEdenSize) {
2263 young_list_max_length -= _max_survivor_regions;
2264 }
2265 if (young_list_length < young_list_max_length) {
2266 ret = true;
2267 ++_region_num_young;
2268 } else {
2269 ret = false;
2270 ++_region_num_tenured;
2271 }
2272
2273 return ret;
2274 }
2275
2276 #ifndef PRODUCT
2277 // for debugging, bit of a hack...
2278 static char*
2279 region_num_to_mbs(int length) {
2280 static char buffer[64];
2281 double bytes = (double) (length * HeapRegion::GrainBytes);
2282 double mbs = bytes / (double) (1024 * 1024);
2283 sprintf(buffer, "%7.2lfMB", mbs);
2284 return buffer;
2285 }
2286 #endif // PRODUCT
2287
2288 size_t G1CollectorPolicy::max_regions(int purpose) {
2289 switch (purpose) {
2290 case GCAllocForSurvived:
2291 return _max_survivor_regions;
2292 case GCAllocForTenured:
2293 return REGIONS_UNLIMITED;
2294 default:
2295 ShouldNotReachHere();
2296 return REGIONS_UNLIMITED;
2297 };
2298 }
2299
2300 // Calculates survivor space parameters.
2301 void G1CollectorPolicy::calculate_survivors_policy()
2302 {
2303 if (G1FixedSurvivorSpaceSize == 0) {
2304 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2305 } else {
2306 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2307 }
2308
2309 if (G1FixedTenuringThreshold) {
2310 _tenuring_threshold = MaxTenuringThreshold;
2311 } else {
2312 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2313 HeapRegion::GrainWords * _max_survivor_regions);
2314 }
2315 }
2316
2317 bool
2318 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
2319 word_size) {
2320 assert(_g1->regions_accounted_for(), "Region leakage!");
2321 double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
2322
2323 size_t young_list_length = _g1->young_list()->length();
2324 size_t young_list_max_length = _young_list_target_length;
2325 if (G1FixedEdenSize) {
2326 young_list_max_length -= _max_survivor_regions;
2327 }
2328 bool reached_target_length = young_list_length >= young_list_max_length;
2329
2330 if (in_young_gc_mode()) {
2331 if (reached_target_length) {
2332 assert( young_list_length > 0 && _g1->young_list()->length() > 0,
2333 "invariant" );
2334 return true;
2335 }
2336 } else {
2337 guarantee( false, "should not reach here" );
2338 }
2339
2340 return false;
2341 }
2342
2343 #ifndef PRODUCT
2344 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2345 CollectionSetChooser* _chooser;
2346 public:
2347 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2348 _chooser(chooser) {}
2349
2350 bool doHeapRegion(HeapRegion* r) {
2351 if (!r->continuesHumongous()) {
2352 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2353 }
2354 return false;
2355 }
2356 };
2357
2358 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2359 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2360 _g1->heap_region_iterate(&cl);
2361 return true;
2362 }
2363 #endif
2364
2365 bool
2366 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2367 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2368 if (!during_cycle) {
2369 set_initiate_conc_mark_if_possible();
2370 return true;
2371 } else {
2372 return false;
2373 }
2374 }
2375
2376 void
2377 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2378 // We are about to decide on whether this pause will be an
2379 // initial-mark pause.
2380
2381 // First, during_initial_mark_pause() should not be already set. We
2382 // will set it here if we have to. However, it should be cleared by
2383 // the end of the pause (it's only set for the duration of an
2384 // initial-mark pause).
2385 assert(!during_initial_mark_pause(), "pre-condition");
2386
2387 if (initiate_conc_mark_if_possible()) {
2388 // We had noticed on a previous pause that the heap occupancy has
2389 // gone over the initiating threshold and we should start a
2390 // concurrent marking cycle. So we might initiate one.
2391
2392 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2393 if (!during_cycle) {
2394 // The concurrent marking thread is not "during a cycle", i.e.,
2395 // it has completed the last one. So we can go ahead and
2396 // initiate a new cycle.
2397
2398 set_during_initial_mark_pause();
2399
2400 // And we can now clear initiate_conc_mark_if_possible() as
2401 // we've already acted on it.
2402 clear_initiate_conc_mark_if_possible();
2403 } else {
2404 // The concurrent marking thread is still finishing up the
2405 // previous cycle. If we start one right now the two cycles
2406 // overlap. In particular, the concurrent marking thread might
2407 // be in the process of clearing the next marking bitmap (which
2408 // we will use for the next cycle if we start one). Starting a
2409 // cycle now will be bad given that parts of the marking
2410 // information might get cleared by the marking thread. And we
2411 // cannot wait for the marking thread to finish the cycle as it
2412 // periodically yields while clearing the next marking bitmap
2413 // and, if it's in a yield point, it's waiting for us to
2414 // finish. So, at this point we will not start a cycle and we'll
2415 // let the concurrent marking thread complete the last one.
2416 }
2417 }
2418 }
2419
2420 void
2421 G1CollectorPolicy_BestRegionsFirst::
2422 record_collection_pause_start(double start_time_sec, size_t start_used) {
2423 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2424 }
2425
2426 class NextNonCSElemFinder: public HeapRegionClosure {
2427 HeapRegion* _res;
2428 public:
2429 NextNonCSElemFinder(): _res(NULL) {}
2430 bool doHeapRegion(HeapRegion* r) {
2431 if (!r->in_collection_set()) {
2432 _res = r;
2433 return true;
2434 } else {
2435 return false;
2436 }
2437 }
2438 HeapRegion* res() { return _res; }
2439 };
2440
2441 class KnownGarbageClosure: public HeapRegionClosure {
2442 CollectionSetChooser* _hrSorted;
2443
2444 public:
2445 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2446 _hrSorted(hrSorted)
2447 {}
2448
2449 bool doHeapRegion(HeapRegion* r) {
2450 // We only include humongous regions in collection
2451 // sets when concurrent mark shows that their contained object is
2452 // unreachable.
2453
2454 // Do we have any marking information for this region?
2455 if (r->is_marked()) {
2456 // We don't include humongous regions in collection
2457 // sets because we collect them immediately at the end of a marking
2458 // cycle. We also don't include young regions because we *must*
2459 // include them in the next collection pause.
2460 if (!r->isHumongous() && !r->is_young()) {
2461 _hrSorted->addMarkedHeapRegion(r);
2462 }
2463 }
2464 return false;
2465 }
2466 };
2467
2468 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2469 CollectionSetChooser* _hrSorted;
2470 jint _marked_regions_added;
2471 jint _chunk_size;
2472 jint _cur_chunk_idx;
2473 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2474 int _worker;
2475 int _invokes;
2476
2477 void get_new_chunk() {
2478 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2479 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2480 }
2481 void add_region(HeapRegion* r) {
2482 if (_cur_chunk_idx == _cur_chunk_end) {
2483 get_new_chunk();
2484 }
2485 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2486 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2487 _marked_regions_added++;
2488 _cur_chunk_idx++;
2489 }
2490
2491 public:
2492 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2493 jint chunk_size,
2494 int worker) :
2495 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2496 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2497 _invokes(0)
2498 {}
2499
2500 bool doHeapRegion(HeapRegion* r) {
2501 // We only include humongous regions in collection
2502 // sets when concurrent mark shows that their contained object is
2503 // unreachable.
2504 _invokes++;
2505
2506 // Do we have any marking information for this region?
2507 if (r->is_marked()) {
2508 // We don't include humongous regions in collection
2509 // sets because we collect them immediately at the end of a marking
2510 // cycle.
2511 // We also do not include young regions in collection sets
2512 if (!r->isHumongous() && !r->is_young()) {
2513 add_region(r);
2514 }
2515 }
2516 return false;
2517 }
2518 jint marked_regions_added() { return _marked_regions_added; }
2519 int invokes() { return _invokes; }
2520 };
2521
2522 class ParKnownGarbageTask: public AbstractGangTask {
2523 CollectionSetChooser* _hrSorted;
2524 jint _chunk_size;
2525 G1CollectedHeap* _g1;
2526 public:
2527 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2528 AbstractGangTask("ParKnownGarbageTask"),
2529 _hrSorted(hrSorted), _chunk_size(chunk_size),
2530 _g1(G1CollectedHeap::heap())
2531 {}
2532
2533 void work(int i) {
2534 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2535 // Back to zero for the claim value.
2536 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2537 HeapRegion::InitialClaimValue);
2538 jint regions_added = parKnownGarbageCl.marked_regions_added();
2539 _hrSorted->incNumMarkedHeapRegions(regions_added);
2540 if (G1PrintParCleanupStats) {
2541 gclog_or_tty->print(" Thread %d called %d times, added %d regions to list.\n",
2542 i, parKnownGarbageCl.invokes(), regions_added);
2543 }
2544 }
2545 };
2546
2547 void
2548 G1CollectorPolicy_BestRegionsFirst::
2549 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2550 size_t max_live_bytes) {
2551 double start;
2552 if (G1PrintParCleanupStats) start = os::elapsedTime();
2553 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2554
2555 _collectionSetChooser->clearMarkedHeapRegions();
2556 double clear_marked_end;
2557 if (G1PrintParCleanupStats) {
2558 clear_marked_end = os::elapsedTime();
2559 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2560 (clear_marked_end - start)*1000.0);
2561 }
2562 if (ParallelGCThreads > 0) {
2563 const size_t OverpartitionFactor = 4;
2564 const size_t MinWorkUnit = 8;
2565 const size_t WorkUnit =
2566 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2567 MinWorkUnit);
2568 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2569 WorkUnit);
2570 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2571 (int) WorkUnit);
2572 _g1->workers()->run_task(&parKnownGarbageTask);
2573
2574 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2575 "sanity check");
2576 } else {
2577 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2578 _g1->heap_region_iterate(&knownGarbagecl);
2579 }
2580 double known_garbage_end;
2581 if (G1PrintParCleanupStats) {
2582 known_garbage_end = os::elapsedTime();
2583 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2584 (known_garbage_end - clear_marked_end)*1000.0);
2585 }
2586 _collectionSetChooser->sortMarkedHeapRegions();
2587 double sort_end;
2588 if (G1PrintParCleanupStats) {
2589 sort_end = os::elapsedTime();
2590 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2591 (sort_end - known_garbage_end)*1000.0);
2592 }
2593
2594 record_concurrent_mark_cleanup_end_work2();
2595 double work2_end;
2596 if (G1PrintParCleanupStats) {
2597 work2_end = os::elapsedTime();
2598 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2599 (work2_end - sort_end)*1000.0);
2600 }
2601 }
2602
2603 // Add the heap region at the head of the non-incremental collection set
2604 void G1CollectorPolicy::
2605 add_to_collection_set(HeapRegion* hr) {
2606 assert(_inc_cset_build_state == Active, "Precondition");
2607 assert(!hr->is_young(), "non-incremental add of young region");
2608
2609 if (G1PrintHeapRegions) {
2610 gclog_or_tty->print_cr("added region to cset "
2611 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2612 "top "PTR_FORMAT", %s",
2613 hr->hrs_index(), hr->bottom(), hr->end(),
2614 hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
2615 }
2616
2617 if (_g1->mark_in_progress())
2618 _g1->concurrent_mark()->registerCSetRegion(hr);
2619
2620 assert(!hr->in_collection_set(), "should not already be in the CSet");
2621 hr->set_in_collection_set(true);
2622 hr->set_next_in_collection_set(_collection_set);
2623 _collection_set = hr;
2624 _collection_set_size++;
2625 _collection_set_bytes_used_before += hr->used();
2626 _g1->register_region_with_in_cset_fast_test(hr);
2627 }
2628
2629 // Initialize the per-collection-set information
2630 void G1CollectorPolicy::start_incremental_cset_building() {
2631 assert(_inc_cset_build_state == Inactive, "Precondition");
2632
2633 _inc_cset_head = NULL;
2634 _inc_cset_tail = NULL;
2635 _inc_cset_size = 0;
2636 _inc_cset_bytes_used_before = 0;
2637
2638 if (in_young_gc_mode()) {
2639 _inc_cset_young_index = 0;
2640 }
2641
2642 _inc_cset_max_finger = 0;
2643 _inc_cset_recorded_young_bytes = 0;
2644 _inc_cset_recorded_rs_lengths = 0;
2645 _inc_cset_predicted_elapsed_time_ms = 0;
2646 _inc_cset_predicted_bytes_to_copy = 0;
2647 _inc_cset_build_state = Active;
2648 }
2649
2650 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2651 // This routine is used when:
2652 // * adding survivor regions to the incremental cset at the end of an
2653 // evacuation pause,
2654 // * adding the current allocation region to the incremental cset
2655 // when it is retired, and
2656 // * updating existing policy information for a region in the
2657 // incremental cset via young list RSet sampling.
2658 // Therefore this routine may be called at a safepoint by the
2659 // VM thread, or in-between safepoints by mutator threads (when
2660 // retiring the current allocation region) or a concurrent
2661 // refine thread (RSet sampling).
2662
2663 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2664 size_t used_bytes = hr->used();
2665
2666 _inc_cset_recorded_rs_lengths += rs_length;
2667 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2668
2669 _inc_cset_bytes_used_before += used_bytes;
2670
2671 // Cache the values we have added to the aggregated informtion
2672 // in the heap region in case we have to remove this region from
2673 // the incremental collection set, or it is updated by the
2674 // rset sampling code
2675 hr->set_recorded_rs_length(rs_length);
2676 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2677
2678 #if PREDICTIONS_VERBOSE
2679 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2680 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2681
2682 // Record the number of bytes used in this region
2683 _inc_cset_recorded_young_bytes += used_bytes;
2684
2685 // Cache the values we have added to the aggregated informtion
2686 // in the heap region in case we have to remove this region from
2687 // the incremental collection set, or it is updated by the
2688 // rset sampling code
2689 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2690 #endif // PREDICTIONS_VERBOSE
2691 }
2692
2693 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2694 // This routine is currently only called as part of the updating of
2695 // existing policy information for regions in the incremental cset that
2696 // is performed by the concurrent refine thread(s) as part of young list
2697 // RSet sampling. Therefore we should not be at a safepoint.
2698
2699 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2700 assert(hr->is_young(), "it should be");
2701
2702 size_t used_bytes = hr->used();
2703 size_t old_rs_length = hr->recorded_rs_length();
2704 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2705
2706 // Subtract the old recorded/predicted policy information for
2707 // the given heap region from the collection set info.
2708 _inc_cset_recorded_rs_lengths -= old_rs_length;
2709 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2710
2711 _inc_cset_bytes_used_before -= used_bytes;
2712
2713 // Clear the values cached in the heap region
2714 hr->set_recorded_rs_length(0);
2715 hr->set_predicted_elapsed_time_ms(0);
2716
2717 #if PREDICTIONS_VERBOSE
2718 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2719 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2720
2721 // Subtract the number of bytes used in this region
2722 _inc_cset_recorded_young_bytes -= used_bytes;
2723
2724 // Clear the values cached in the heap region
2725 hr->set_predicted_bytes_to_copy(0);
2726 #endif // PREDICTIONS_VERBOSE
2727 }
2728
2729 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2730 // Update the collection set information that is dependent on the new RS length
2731 assert(hr->is_young(), "Precondition");
2732
2733 remove_from_incremental_cset_info(hr);
2734 add_to_incremental_cset_info(hr, new_rs_length);
2735 }
2736
2737 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2738 assert( hr->is_young(), "invariant");
2739 assert( hr->young_index_in_cset() == -1, "invariant" );
2740 assert(_inc_cset_build_state == Active, "Precondition");
2741
2742 // We need to clear and set the cached recorded/cached collection set
2743 // information in the heap region here (before the region gets added
2744 // to the collection set). An individual heap region's cached values
2745 // are calculated, aggregated with the policy collection set info,
2746 // and cached in the heap region here (initially) and (subsequently)
2747 // by the Young List sampling code.
2748
2749 size_t rs_length = hr->rem_set()->occupied();
2750 add_to_incremental_cset_info(hr, rs_length);
2751
2752 HeapWord* hr_end = hr->end();
2753 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2754
2755 assert(!hr->in_collection_set(), "invariant");
2756 hr->set_in_collection_set(true);
2757 assert( hr->next_in_collection_set() == NULL, "invariant");
2758
2759 _inc_cset_size++;
2760 _g1->register_region_with_in_cset_fast_test(hr);
2761
2762 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2763 ++_inc_cset_young_index;
2764 }
2765
2766 // Add the region at the RHS of the incremental cset
2767 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2768 // We should only ever be appending survivors at the end of a pause
2769 assert( hr->is_survivor(), "Logic");
2770
2771 // Do the 'common' stuff
2772 add_region_to_incremental_cset_common(hr);
2773
2774 // Now add the region at the right hand side
2775 if (_inc_cset_tail == NULL) {
2776 assert(_inc_cset_head == NULL, "invariant");
2777 _inc_cset_head = hr;
2778 } else {
2779 _inc_cset_tail->set_next_in_collection_set(hr);
2780 }
2781 _inc_cset_tail = hr;
2782
2783 if (G1PrintHeapRegions) {
2784 gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
2785 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2786 "top "PTR_FORMAT", young %s",
2787 hr->hrs_index(), hr->bottom(), hr->end(),
2788 hr->top(), (hr->is_young()) ? "YES" : "NO");
2789 }
2790 }
2791
2792 // Add the region to the LHS of the incremental cset
2793 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2794 // Survivors should be added to the RHS at the end of a pause
2795 assert(!hr->is_survivor(), "Logic");
2796
2797 // Do the 'common' stuff
2798 add_region_to_incremental_cset_common(hr);
2799
2800 // Add the region at the left hand side
2801 hr->set_next_in_collection_set(_inc_cset_head);
2802 if (_inc_cset_head == NULL) {
2803 assert(_inc_cset_tail == NULL, "Invariant");
2804 _inc_cset_tail = hr;
2805 }
2806 _inc_cset_head = hr;
2807
2808 if (G1PrintHeapRegions) {
2809 gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
2810 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2811 "top "PTR_FORMAT", young %s",
2812 hr->hrs_index(), hr->bottom(), hr->end(),
2813 hr->top(), (hr->is_young()) ? "YES" : "NO");
2814 }
2815 }
2816
2817 #ifndef PRODUCT
2818 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2819 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2820
2821 st->print_cr("\nCollection_set:");
2822 HeapRegion* csr = list_head;
2823 while (csr != NULL) {
2824 HeapRegion* next = csr->next_in_collection_set();
2825 assert(csr->in_collection_set(), "bad CS");
2826 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2827 "age: %4d, y: %d, surv: %d",
2828 csr->bottom(), csr->end(),
2829 csr->top(),
2830 csr->prev_top_at_mark_start(),
2831 csr->next_top_at_mark_start(),
2832 csr->top_at_conc_mark_count(),
2833 csr->age_in_surv_rate_group_cond(),
2834 csr->is_young(),
2835 csr->is_survivor());
2836 csr = next;
2837 }
2838 }
2839 #endif // !PRODUCT
2840
2841 void
2842 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2843 double target_pause_time_ms) {
2844 // Set this here - in case we're not doing young collections.
2845 double non_young_start_time_sec = os::elapsedTime();
2846
2847 start_recording_regions();
2848
2849 guarantee(target_pause_time_ms > 0.0,
2850 err_msg("target_pause_time_ms = %1.6lf should be positive",
2851 target_pause_time_ms));
2852 guarantee(_collection_set == NULL, "Precondition");
2853
2854 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2855 double predicted_pause_time_ms = base_time_ms;
2856
2857 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2858
2859 // the 10% and 50% values are arbitrary...
2860 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2861 time_remaining_ms = 0.50 * target_pause_time_ms;
2862 _within_target = false;
2863 } else {
2864 _within_target = true;
2865 }
2866
2867 // We figure out the number of bytes available for future to-space.
2868 // For new regions without marking information, we must assume the
2869 // worst-case of complete survival. If we have marking information for a
2870 // region, we can bound the amount of live data. We can add a number of
2871 // such regions, as long as the sum of the live data bounds does not
2872 // exceed the available evacuation space.
2873 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2874
2875 size_t expansion_bytes =
2876 _g1->expansion_regions() * HeapRegion::GrainBytes;
2877
2878 _collection_set_bytes_used_before = 0;
2879 _collection_set_size = 0;
2880
2881 // Adjust for expansion and slop.
2882 max_live_bytes = max_live_bytes + expansion_bytes;
2883
2884 assert(_g1->regions_accounted_for(), "Region leakage!");
2885
2886 HeapRegion* hr;
2887 if (in_young_gc_mode()) {
2888 double young_start_time_sec = os::elapsedTime();
2889
2890 if (G1PolicyVerbose > 0) {
2891 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2892 _g1->young_list()->length());
2893 }
2894
2895 _young_cset_length = 0;
2896 _last_young_gc_full = full_young_gcs() ? true : false;
2897
2898 if (_last_young_gc_full)
2899 ++_full_young_pause_num;
2900 else
2901 ++_partial_young_pause_num;
2902
2903 // The young list is laid with the survivor regions from the previous
2904 // pause are appended to the RHS of the young list, i.e.
2905 // [Newly Young Regions ++ Survivors from last pause].
2906
2907 hr = _g1->young_list()->first_survivor_region();
2908 while (hr != NULL) {
2909 assert(hr->is_survivor(), "badly formed young list");
2910 hr->set_young();
2911 hr = hr->get_next_young_region();
2912 }
2913
2914 // Clear the fields that point to the survivor list - they are
2915 // all young now.
2916 _g1->young_list()->clear_survivors();
2917
2918 if (_g1->mark_in_progress())
2919 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2920
2921 _young_cset_length = _inc_cset_young_index;
2922 _collection_set = _inc_cset_head;
2923 _collection_set_size = _inc_cset_size;
2924 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2925
2926 // For young regions in the collection set, we assume the worst
2927 // case of complete survival
2928 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2929
2930 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2931 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2932
2933 // The number of recorded young regions is the incremental
2934 // collection set's current size
2935 set_recorded_young_regions(_inc_cset_size);
2936 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2937 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2938 #if PREDICTIONS_VERBOSE
2939 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2940 #endif // PREDICTIONS_VERBOSE
2941
2942 if (G1PolicyVerbose > 0) {
2943 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2944 _inc_cset_size);
2945 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2946 max_live_bytes/K);
2947 }
2948
2949 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2950
2951 double young_end_time_sec = os::elapsedTime();
2952 _recorded_young_cset_choice_time_ms =
2953 (young_end_time_sec - young_start_time_sec) * 1000.0;
2954
2955 // We are doing young collections so reset this.
2956 non_young_start_time_sec = young_end_time_sec;
2957
2958 // Note we can use either _collection_set_size or
2959 // _young_cset_length here
2960 if (_collection_set_size > 0 && _last_young_gc_full) {
2961 // don't bother adding more regions...
2962 goto choose_collection_set_end;
2963 }
2964 }
2965
2966 if (!in_young_gc_mode() || !full_young_gcs()) {
2967 bool should_continue = true;
2968 NumberSeq seq;
2969 double avg_prediction = 100000000000000000.0; // something very large
2970
2971 do {
2972 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2973 avg_prediction);
2974 if (hr != NULL) {
2975 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2976 time_remaining_ms -= predicted_time_ms;
2977 predicted_pause_time_ms += predicted_time_ms;
2978 add_to_collection_set(hr);
2979 record_non_young_cset_region(hr);
2980 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2981 if (G1PolicyVerbose > 0) {
2982 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2983 max_live_bytes/K);
2984 }
2985 seq.add(predicted_time_ms);
2986 avg_prediction = seq.avg() + seq.sd();
2987 }
2988 should_continue =
2989 ( hr != NULL) &&
2990 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
2991 : _collection_set_size < _young_list_fixed_length );
2992 } while (should_continue);
2993
2994 if (!adaptive_young_list_length() &&
2995 _collection_set_size < _young_list_fixed_length)
2996 _should_revert_to_full_young_gcs = true;
2997 }
2998
2999 choose_collection_set_end:
3000 stop_incremental_cset_building();
3001
3002 count_CS_bytes_used();
3003
3004 end_recording_regions();
3005
3006 double non_young_end_time_sec = os::elapsedTime();
3007 _recorded_non_young_cset_choice_time_ms =
3008 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3009 }
3010
3011 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3012 G1CollectorPolicy::record_full_collection_end();
3013 _collectionSetChooser->updateAfterFullCollection();
3014 }
3015
3016 void G1CollectorPolicy_BestRegionsFirst::
3017 expand_if_possible(size_t numRegions) {
3018 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3019 _g1->expand(expansion_bytes);
3020 }
3021
3022 void G1CollectorPolicy_BestRegionsFirst::
3023 record_collection_pause_end() {
3024 G1CollectorPolicy::record_collection_pause_end();
3025 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3026 }