1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 "precompiled.hpp"
26 #include "gc/g1/concurrentG1Refine.hpp"
27 #include "gc/g1/concurrentMark.hpp"
28 #include "gc/g1/concurrentMarkThread.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/g1CollectorPolicy.hpp"
31 #include "gc/g1/g1IHOPControl.hpp"
32 #include "gc/g1/g1ErgoVerbose.hpp"
33 #include "gc/g1/g1GCPhaseTimes.hpp"
34 #include "gc/g1/g1Log.hpp"
35 #include "gc/g1/heapRegion.inline.hpp"
36 #include "gc/g1/heapRegionRemSet.hpp"
37 #include "gc/shared/gcPolicyCounters.hpp"
38 #include "runtime/arguments.hpp"
39 #include "runtime/java.hpp"
40 #include "runtime/mutexLocker.hpp"
41 #include "utilities/debug.hpp"
42 #include "utilities/pair.hpp"
43
44 // Different defaults for different number of GC threads
45 // They were chosen by running GCOld and SPECjbb on debris with different
46 // numbers of GC threads and choosing them based on the results
47
48 // all the same
49 static double rs_length_diff_defaults[] = {
50 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
51 };
52
53 static double cost_per_card_ms_defaults[] = {
54 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
55 };
56
57 // all the same
58 static double young_cards_per_entry_ratio_defaults[] = {
59 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
60 };
61
62 static double cost_per_entry_ms_defaults[] = {
63 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
64 };
65
66 static double cost_per_byte_ms_defaults[] = {
67 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
68 };
69
70 // these should be pretty consistent
71 static double constant_other_time_ms_defaults[] = {
72 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
73 };
74
75
76 static double young_other_cost_per_region_ms_defaults[] = {
77 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
78 };
79
80 static double non_young_other_cost_per_region_ms_defaults[] = {
81 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
82 };
83
84 G1CollectorPolicy::G1CollectorPolicy() :
85 _predictor(G1ConfidencePercent / 100.0),
86 _parallel_gc_threads(ParallelGCThreads),
87
88 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
89 _stop_world_start(0.0),
90
91 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
92 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
93
94 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
95 _prev_collection_pause_end_ms(0.0),
96 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
97 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
104 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
105 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
106 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _non_young_other_cost_per_region_ms_seq(
108 new TruncatedSeq(TruncatedSeqLength)),
109
110 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
111 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
112
113 _pause_time_target_ms((double) MaxGCPauseMillis),
114
115 _recent_prev_end_times_for_all_gcs_sec(
116 new TruncatedSeq(NumPrevPausesForHeuristics)),
117
118 _recent_avg_pause_time_ratio(0.0),
119 _rs_lengths_prediction(0),
120 _max_survivor_regions(0),
121
122 _eden_used_bytes_before_gc(0),
123 _survivor_used_bytes_before_gc(0),
124 _heap_used_bytes_before_gc(0),
125 _metaspace_used_bytes_before_gc(0),
126 _eden_capacity_bytes_before_gc(0),
127 _heap_capacity_bytes_before_gc(0),
128
129 _eden_cset_region_length(0),
130 _survivor_cset_region_length(0),
131 _old_cset_region_length(0),
132
133 _collection_set(NULL),
134 _collection_set_bytes_used_before(0),
135
136 // Incremental CSet attributes
137 _inc_cset_build_state(Inactive),
138 _inc_cset_head(NULL),
139 _inc_cset_tail(NULL),
140 _inc_cset_bytes_used_before(0),
141 _inc_cset_max_finger(NULL),
142 _inc_cset_recorded_rs_lengths(0),
143 _inc_cset_recorded_rs_lengths_diffs(0),
144 _inc_cset_predicted_elapsed_time_ms(0.0),
145 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
146
147 // add here any more surv rate groups
148 _recorded_survivor_regions(0),
149 _recorded_survivor_head(NULL),
150 _recorded_survivor_tail(NULL),
151 _survivors_age_table(true),
152
153 _gc_overhead_perc(0.0),
154
155 _last_old_allocated_bytes(0),
156 _ihop_control(NULL),
157 _initial_mark_to_mixed() {
158
159 // SurvRateGroups below must be initialized after the predictor because they
160 // indirectly use it through this object passed to their constructor.
161 _short_lived_surv_rate_group =
162 new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
163 _survivor_surv_rate_group =
164 new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
165
166 // Set up the region size and associated fields. Given that the
167 // policy is created before the heap, we have to set this up here,
168 // so it's done as soon as possible.
169
170 // It would have been natural to pass initial_heap_byte_size() and
171 // max_heap_byte_size() to setup_heap_region_size() but those have
172 // not been set up at this point since they should be aligned with
173 // the region size. So, there is a circular dependency here. We base
174 // the region size on the heap size, but the heap size should be
175 // aligned with the region size. To get around this we use the
176 // unaligned values for the heap.
177 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
178 HeapRegionRemSet::setup_remset_size();
179
180 G1ErgoVerbose::initialize();
181 if (PrintAdaptiveSizePolicy) {
182 // Currently, we only use a single switch for all the heuristics.
183 G1ErgoVerbose::set_enabled(true);
184 // Given that we don't currently have a verboseness level
185 // parameter, we'll hardcode this to high. This can be easily
186 // changed in the future.
187 G1ErgoVerbose::set_level(ErgoHigh);
188 } else {
189 G1ErgoVerbose::set_enabled(false);
190 }
191
192 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
193 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
194
195 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
196
197 int index = MIN2(_parallel_gc_threads - 1, 7);
198
199 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
200 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
201 _cost_scan_hcc_seq->add(0.0);
202 _young_cards_per_entry_ratio_seq->add(
203 young_cards_per_entry_ratio_defaults[index]);
204 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
205 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
206 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
207 _young_other_cost_per_region_ms_seq->add(
208 young_other_cost_per_region_ms_defaults[index]);
209 _non_young_other_cost_per_region_ms_seq->add(
210 non_young_other_cost_per_region_ms_defaults[index]);
211
212 // Below, we might need to calculate the pause time target based on
213 // the pause interval. When we do so we are going to give G1 maximum
214 // flexibility and allow it to do pauses when it needs to. So, we'll
215 // arrange that the pause interval to be pause time target + 1 to
216 // ensure that a) the pause time target is maximized with respect to
217 // the pause interval and b) we maintain the invariant that pause
218 // time target < pause interval. If the user does not want this
219 // maximum flexibility, they will have to set the pause interval
220 // explicitly.
221
222 // First make sure that, if either parameter is set, its value is
223 // reasonable.
224 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
225 if (MaxGCPauseMillis < 1) {
226 vm_exit_during_initialization("MaxGCPauseMillis should be "
227 "greater than 0");
228 }
229 }
230 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
231 if (GCPauseIntervalMillis < 1) {
232 vm_exit_during_initialization("GCPauseIntervalMillis should be "
233 "greater than 0");
234 }
235 }
236
237 // Then, if the pause time target parameter was not set, set it to
238 // the default value.
239 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
240 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
241 // The default pause time target in G1 is 200ms
242 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
243 } else {
244 // We do not allow the pause interval to be set without the
245 // pause time target
246 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
247 "without setting MaxGCPauseMillis");
248 }
249 }
250
251 // Then, if the interval parameter was not set, set it according to
252 // the pause time target (this will also deal with the case when the
253 // pause time target is the default value).
254 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
255 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
256 }
257
258 // Finally, make sure that the two parameters are consistent.
259 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
260 char buffer[256];
261 jio_snprintf(buffer, 256,
262 "MaxGCPauseMillis (%u) should be less than "
263 "GCPauseIntervalMillis (%u)",
264 MaxGCPauseMillis, GCPauseIntervalMillis);
265 vm_exit_during_initialization(buffer);
266 }
267
268 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
269 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
270 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
271
272 // start conservatively (around 50ms is about right)
273 _concurrent_mark_remark_times_ms->add(0.05);
274 _concurrent_mark_cleanup_times_ms->add(0.20);
275 _tenuring_threshold = MaxTenuringThreshold;
276
277 assert(GCTimeRatio > 0,
278 "we should have set it to a default value set_g1_gc_flags() "
279 "if a user set it to 0");
280 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
281
282 uintx reserve_perc = G1ReservePercent;
283 // Put an artificial ceiling on this so that it's not set to a silly value.
284 if (reserve_perc > 50) {
285 reserve_perc = 50;
286 warning("G1ReservePercent is set to a value that is too large, "
287 "it's been updated to " UINTX_FORMAT, reserve_perc);
288 }
289 _reserve_factor = (double) reserve_perc / 100.0;
290 // This will be set when the heap is expanded
291 // for the first time during initialization.
292 _reserve_regions = 0;
293
294 _collectionSetChooser = new CollectionSetChooser();
295 }
296
297 G1CollectorPolicy::~G1CollectorPolicy() {
298 delete _ihop_control;
299 }
300
301 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
302 return _predictor.get_new_prediction(seq);
303 }
304
305 void G1CollectorPolicy::initialize_alignments() {
306 _space_alignment = HeapRegion::GrainBytes;
307 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
308 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
309 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
310 }
311
312 void G1CollectorPolicy::initialize_flags() {
313 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
314 FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
315 }
316
317 if (SurvivorRatio < 1) {
318 vm_exit_during_initialization("Invalid survivor ratio specified");
319 }
320 CollectorPolicy::initialize_flags();
321 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
322 }
323
324 void G1CollectorPolicy::post_heap_initialize() {
325 uintx max_regions = G1CollectedHeap::heap()->max_regions();
326 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
327 if (max_young_size != MaxNewSize) {
328 FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
329 }
330
331 _ihop_control = create_ihop_control();
332 }
333
334 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
335
336 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
337 _min_desired_young_length(0), _max_desired_young_length(0) {
338 if (FLAG_IS_CMDLINE(NewRatio)) {
339 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
340 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
341 } else {
342 _sizer_kind = SizerNewRatio;
343 _adaptive_size = false;
344 return;
345 }
346 }
347
348 if (NewSize > MaxNewSize) {
349 if (FLAG_IS_CMDLINE(MaxNewSize)) {
350 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
351 "A new max generation size of " SIZE_FORMAT "k will be used.",
352 NewSize/K, MaxNewSize/K, NewSize/K);
353 }
354 MaxNewSize = NewSize;
355 }
356
357 if (FLAG_IS_CMDLINE(NewSize)) {
358 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
359 1U);
360 if (FLAG_IS_CMDLINE(MaxNewSize)) {
361 _max_desired_young_length =
362 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
363 1U);
364 _sizer_kind = SizerMaxAndNewSize;
365 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
366 } else {
367 _sizer_kind = SizerNewSizeOnly;
368 }
369 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
370 _max_desired_young_length =
371 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
372 1U);
373 _sizer_kind = SizerMaxNewSizeOnly;
374 }
375 }
376
377 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
378 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
379 return MAX2(1U, default_value);
380 }
381
382 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
383 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
384 return MAX2(1U, default_value);
385 }
386
387 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
388 assert(number_of_heap_regions > 0, "Heap must be initialized");
389
390 switch (_sizer_kind) {
391 case SizerDefaults:
392 *min_young_length = calculate_default_min_length(number_of_heap_regions);
393 *max_young_length = calculate_default_max_length(number_of_heap_regions);
394 break;
395 case SizerNewSizeOnly:
396 *max_young_length = calculate_default_max_length(number_of_heap_regions);
397 *max_young_length = MAX2(*min_young_length, *max_young_length);
398 break;
399 case SizerMaxNewSizeOnly:
400 *min_young_length = calculate_default_min_length(number_of_heap_regions);
401 *min_young_length = MIN2(*min_young_length, *max_young_length);
402 break;
403 case SizerMaxAndNewSize:
404 // Do nothing. Values set on the command line, don't update them at runtime.
405 break;
406 case SizerNewRatio:
407 *min_young_length = number_of_heap_regions / (NewRatio + 1);
408 *max_young_length = *min_young_length;
409 break;
410 default:
411 ShouldNotReachHere();
412 }
413
414 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
415 }
416
417 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
418 // We need to pass the desired values because recalculation may not update these
419 // values in some cases.
420 uint temp = _min_desired_young_length;
421 uint result = _max_desired_young_length;
422 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
423 return result;
424 }
425
426 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
427 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
428 &_max_desired_young_length);
429 }
430
431 void G1CollectorPolicy::init() {
432 // Set aside an initial future to_space.
433 _g1 = G1CollectedHeap::heap();
434
435 assert(Heap_lock->owned_by_self(), "Locking discipline.");
436
437 initialize_gc_policy_counters();
438
439 if (adaptive_young_list_length()) {
440 _young_list_fixed_length = 0;
441 } else {
442 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
443 }
444 _free_regions_at_end_of_collection = _g1->num_free_regions();
445
446 update_young_list_max_and_target_length();
447 // We may immediately start allocating regions and placing them on the
448 // collection set list. Initialize the per-collection set info
449 start_incremental_cset_building();
450 }
451
452 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
453 phase_times()->note_gc_start(num_active_workers);
454 }
455
456 // Create the jstat counters for the policy.
457 void G1CollectorPolicy::initialize_gc_policy_counters() {
458 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
459 }
460
461 bool G1CollectorPolicy::predict_will_fit(uint young_length,
462 double base_time_ms,
463 uint base_free_regions,
464 double target_pause_time_ms) const {
465 if (young_length >= base_free_regions) {
466 // end condition 1: not enough space for the young regions
467 return false;
468 }
469
470 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
471 size_t bytes_to_copy =
472 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
473 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
474 double young_other_time_ms = predict_young_other_time_ms(young_length);
475 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
476 if (pause_time_ms > target_pause_time_ms) {
477 // end condition 2: prediction is over the target pause time
478 return false;
479 }
480
481 size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
482
483 // When copying, we will likely need more bytes free than is live in the region.
484 // Add some safety margin to factor in the confidence of our guess, and the
485 // natural expected waste.
486 // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
487 // of the calculation: the lower the confidence, the more headroom.
488 // (100 + TargetPLABWastePct) represents the increase in expected bytes during
489 // copying due to anticipated waste in the PLABs.
490 double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
491 size_t expected_bytes_to_copy = safety_factor * bytes_to_copy;
492
493 if (expected_bytes_to_copy > free_bytes) {
494 // end condition 3: out-of-space
495 return false;
496 }
497
498 // success!
499 return true;
500 }
501
502 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
503 // re-calculate the necessary reserve
504 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
505 // We use ceiling so that if reserve_regions_d is > 0.0 (but
506 // smaller than 1.0) we'll get 1.
507 _reserve_regions = (uint) ceil(reserve_regions_d);
508
509 _young_gen_sizer->heap_size_changed(new_number_of_regions);
510 }
511
512 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
513 uint base_min_length) const {
514 uint desired_min_length = 0;
515 if (adaptive_young_list_length()) {
516 if (_alloc_rate_ms_seq->num() > 3) {
517 double now_sec = os::elapsedTime();
518 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
519 double alloc_rate_ms = predict_alloc_rate_ms();
520 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
521 } else {
522 // otherwise we don't have enough info to make the prediction
523 }
524 }
525 desired_min_length += base_min_length;
526 // make sure we don't go below any user-defined minimum bound
527 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
528 }
529
530 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
531 // Here, we might want to also take into account any additional
532 // constraints (i.e., user-defined minimum bound). Currently, we
533 // effectively don't set this bound.
534 return _young_gen_sizer->max_desired_young_length();
535 }
536
537 uint G1CollectorPolicy::update_young_list_max_and_target_length() {
538 return update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq));
539 }
540
541 uint G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
542 uint unbounded_target_length = update_young_list_target_length(rs_lengths);
543 update_max_gc_locker_expansion();
544 return unbounded_target_length;
545 }
546
547 uint G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
548 YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
549 _young_list_target_length = young_lengths.first;
550 return young_lengths.second;
551 }
552
553 G1CollectorPolicy::YoungTargetLengths G1CollectorPolicy::young_list_target_lengths(size_t rs_lengths) const {
554 YoungTargetLengths result;
555
556 // Calculate the absolute and desired min bounds first.
557
558 // This is how many young regions we already have (currently: the survivors).
559 uint base_min_length = recorded_survivor_regions();
560 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
561 // This is the absolute minimum young length. Ensure that we
562 // will at least have one eden region available for allocation.
563 uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
564 // If we shrank the young list target it should not shrink below the current size.
565 desired_min_length = MAX2(desired_min_length, absolute_min_length);
566 // Calculate the absolute and desired max bounds.
567
568 uint desired_max_length = calculate_young_list_desired_max_length();
569
570 uint young_list_target_length = 0;
571 if (adaptive_young_list_length()) {
572 if (collector_state()->gcs_are_young()) {
573 young_list_target_length =
574 calculate_young_list_target_length(rs_lengths,
575 base_min_length,
576 desired_min_length,
577 desired_max_length);
578 } else {
579 // Don't calculate anything and let the code below bound it to
580 // the desired_min_length, i.e., do the next GC as soon as
581 // possible to maximize how many old regions we can add to it.
582 }
583 } else {
584 // The user asked for a fixed young gen so we'll fix the young gen
585 // whether the next GC is young or mixed.
586 young_list_target_length = _young_list_fixed_length;
587 }
588
589 result.second = young_list_target_length;
590
591 // We will try our best not to "eat" into the reserve.
592 uint absolute_max_length = 0;
593 if (_free_regions_at_end_of_collection > _reserve_regions) {
594 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
595 }
596 if (desired_max_length > absolute_max_length) {
597 desired_max_length = absolute_max_length;
598 }
599
600 // Make sure we don't go over the desired max length, nor under the
601 // desired min length. In case they clash, desired_min_length wins
602 // which is why that test is second.
603 if (young_list_target_length > desired_max_length) {
604 young_list_target_length = desired_max_length;
605 }
606 if (young_list_target_length < desired_min_length) {
607 young_list_target_length = desired_min_length;
608 }
609
610 assert(young_list_target_length > recorded_survivor_regions(),
611 "we should be able to allocate at least one eden region");
612 assert(young_list_target_length >= absolute_min_length, "post-condition");
613
614 result.first = young_list_target_length;
615 return result;
616 }
617
618 uint
619 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
620 uint base_min_length,
621 uint desired_min_length,
622 uint desired_max_length) const {
623 assert(adaptive_young_list_length(), "pre-condition");
624 assert(collector_state()->gcs_are_young(), "only call this for young GCs");
625
626 // In case some edge-condition makes the desired max length too small...
627 if (desired_max_length <= desired_min_length) {
628 return desired_min_length;
629 }
630
631 // We'll adjust min_young_length and max_young_length not to include
632 // the already allocated young regions (i.e., so they reflect the
633 // min and max eden regions we'll allocate). The base_min_length
634 // will be reflected in the predictions by the
635 // survivor_regions_evac_time prediction.
636 assert(desired_min_length > base_min_length, "invariant");
637 uint min_young_length = desired_min_length - base_min_length;
638 assert(desired_max_length > base_min_length, "invariant");
639 uint max_young_length = desired_max_length - base_min_length;
640
641 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
642 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
643 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
644 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
645 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
646 double base_time_ms =
647 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
648 survivor_regions_evac_time;
649 uint available_free_regions = _free_regions_at_end_of_collection;
650 uint base_free_regions = 0;
651 if (available_free_regions > _reserve_regions) {
652 base_free_regions = available_free_regions - _reserve_regions;
653 }
654
655 // Here, we will make sure that the shortest young length that
656 // makes sense fits within the target pause time.
657
658 if (predict_will_fit(min_young_length, base_time_ms,
659 base_free_regions, target_pause_time_ms)) {
660 // The shortest young length will fit into the target pause time;
661 // we'll now check whether the absolute maximum number of young
662 // regions will fit in the target pause time. If not, we'll do
663 // a binary search between min_young_length and max_young_length.
664 if (predict_will_fit(max_young_length, base_time_ms,
665 base_free_regions, target_pause_time_ms)) {
666 // The maximum young length will fit into the target pause time.
667 // We are done so set min young length to the maximum length (as
668 // the result is assumed to be returned in min_young_length).
669 min_young_length = max_young_length;
670 } else {
671 // The maximum possible number of young regions will not fit within
672 // the target pause time so we'll search for the optimal
673 // length. The loop invariants are:
674 //
675 // min_young_length < max_young_length
676 // min_young_length is known to fit into the target pause time
677 // max_young_length is known not to fit into the target pause time
678 //
679 // Going into the loop we know the above hold as we've just
680 // checked them. Every time around the loop we check whether
681 // the middle value between min_young_length and
682 // max_young_length fits into the target pause time. If it
683 // does, it becomes the new min. If it doesn't, it becomes
684 // the new max. This way we maintain the loop invariants.
685
686 assert(min_young_length < max_young_length, "invariant");
687 uint diff = (max_young_length - min_young_length) / 2;
688 while (diff > 0) {
689 uint young_length = min_young_length + diff;
690 if (predict_will_fit(young_length, base_time_ms,
691 base_free_regions, target_pause_time_ms)) {
692 min_young_length = young_length;
693 } else {
694 max_young_length = young_length;
695 }
696 assert(min_young_length < max_young_length, "invariant");
697 diff = (max_young_length - min_young_length) / 2;
698 }
699 // The results is min_young_length which, according to the
700 // loop invariants, should fit within the target pause time.
701
702 // These are the post-conditions of the binary search above:
703 assert(min_young_length < max_young_length,
704 "otherwise we should have discovered that max_young_length "
705 "fits into the pause target and not done the binary search");
706 assert(predict_will_fit(min_young_length, base_time_ms,
707 base_free_regions, target_pause_time_ms),
708 "min_young_length, the result of the binary search, should "
709 "fit into the pause target");
710 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
711 base_free_regions, target_pause_time_ms),
712 "min_young_length, the result of the binary search, should be "
713 "optimal, so no larger length should fit into the pause target");
714 }
715 } else {
716 // Even the minimum length doesn't fit into the pause time
717 // target, return it as the result nevertheless.
718 }
719 return base_min_length + min_young_length;
720 }
721
722 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
723 double survivor_regions_evac_time = 0.0;
724 for (HeapRegion * r = _recorded_survivor_head;
725 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
726 r = r->get_next_young_region()) {
727 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
728 }
729 return survivor_regions_evac_time;
730 }
731
732 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
733 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
734
735 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
736 if (rs_lengths > _rs_lengths_prediction) {
737 // add 10% to avoid having to recalculate often
738 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
739 update_rs_lengths_prediction(rs_lengths_prediction);
740
741 update_young_list_max_and_target_length(rs_lengths_prediction);
742 }
743 }
744
745 void G1CollectorPolicy::update_rs_lengths_prediction() {
746 update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
747 }
748
749 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
750 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
751 _rs_lengths_prediction = prediction;
752 }
753 }
754
755 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
756 bool is_tlab,
757 bool* gc_overhead_limit_was_exceeded) {
758 guarantee(false, "Not using this policy feature yet.");
759 return NULL;
760 }
761
762 // This method controls how a collector handles one or more
763 // of its generations being fully allocated.
764 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
765 bool is_tlab) {
766 guarantee(false, "Not using this policy feature yet.");
767 return NULL;
768 }
769
770
771 #ifndef PRODUCT
772 bool G1CollectorPolicy::verify_young_ages() {
773 HeapRegion* head = _g1->young_list()->first_region();
774 return
775 verify_young_ages(head, _short_lived_surv_rate_group);
776 // also call verify_young_ages on any additional surv rate groups
777 }
778
779 bool
780 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
781 SurvRateGroup *surv_rate_group) {
782 guarantee( surv_rate_group != NULL, "pre-condition" );
783
784 const char* name = surv_rate_group->name();
785 bool ret = true;
786 int prev_age = -1;
787
788 for (HeapRegion* curr = head;
789 curr != NULL;
790 curr = curr->get_next_young_region()) {
791 SurvRateGroup* group = curr->surv_rate_group();
792 if (group == NULL && !curr->is_survivor()) {
793 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
794 ret = false;
795 }
796
797 if (surv_rate_group == group) {
798 int age = curr->age_in_surv_rate_group();
799
800 if (age < 0) {
801 gclog_or_tty->print_cr("## %s: encountered negative age", name);
802 ret = false;
803 }
804
805 if (age <= prev_age) {
806 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
807 "(%d, %d)", name, age, prev_age);
808 ret = false;
809 }
810 prev_age = age;
811 }
812 }
813
814 return ret;
815 }
816 #endif // PRODUCT
817
818 void G1CollectorPolicy::record_full_collection_start() {
819 _full_collection_start_sec = os::elapsedTime();
820 record_heap_size_info_at_start(true /* full */);
821 // Release the future to-space so that it is available for compaction into.
822 collector_state()->set_full_collection(true);
823 }
824
825 void G1CollectorPolicy::record_full_collection_end() {
826 // Consider this like a collection pause for the purposes of allocation
827 // since last pause.
828 double end_sec = os::elapsedTime();
829 double full_gc_time_sec = end_sec - _full_collection_start_sec;
830 double full_gc_time_ms = full_gc_time_sec * 1000.0;
831
832 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
833
834 update_recent_gc_times(end_sec, full_gc_time_ms);
835
836 collector_state()->set_full_collection(false);
837
838 // "Nuke" the heuristics that control the young/mixed GC
839 // transitions and make sure we start with young GCs after the Full GC.
840 collector_state()->set_gcs_are_young(true);
841 collector_state()->set_last_young_gc(false);
842 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
843 collector_state()->set_during_initial_mark_pause(false);
844 collector_state()->set_in_marking_window(false);
845 collector_state()->set_in_marking_window_im(false);
846
847 _short_lived_surv_rate_group->start_adding_regions();
848 // also call this on any additional surv rate groups
849
850 record_survivor_regions(0, NULL, NULL);
851
852 _free_regions_at_end_of_collection = _g1->num_free_regions();
853 // Reset survivors SurvRateGroup.
854 _survivor_surv_rate_group->reset();
855 update_young_list_max_and_target_length();
856 update_rs_lengths_prediction();
857 _collectionSetChooser->clear();
858
859 _last_old_allocated_bytes = 0;
860
861 record_pause(FullGC, _full_collection_start_sec, end_sec);
862 }
863
864 void G1CollectorPolicy::record_stop_world_start() {
865 _stop_world_start = os::elapsedTime();
866 }
867
868 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
869 // We only need to do this here as the policy will only be applied
870 // to the GC we're about to start. so, no point is calculating this
871 // every time we calculate / recalculate the target young length.
872 update_survivors_policy();
873
874 assert(_g1->used() == _g1->recalculate_used(),
875 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
876 _g1->used(), _g1->recalculate_used());
877
878 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
879 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
880 _stop_world_start = 0.0;
881
882 record_heap_size_info_at_start(false /* full */);
883
884 phase_times()->record_cur_collection_start_sec(start_time_sec);
885 _pending_cards = _g1->pending_card_num();
886
887 _collection_set_bytes_used_before = 0;
888 _bytes_copied_during_gc = 0;
889
890 collector_state()->set_last_gc_was_young(false);
891
892 // do that for any other surv rate groups
893 _short_lived_surv_rate_group->stop_adding_regions();
894 _survivors_age_table.clear();
895
896 assert( verify_young_ages(), "region age verification" );
897 }
898
899 void G1CollectorPolicy::record_concurrent_mark_init_end(double
900 mark_init_elapsed_time_ms) {
901 collector_state()->set_during_marking(true);
902 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
903 collector_state()->set_during_initial_mark_pause(false);
904 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
905 }
906
907 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
908 _mark_remark_start_sec = os::elapsedTime();
909 collector_state()->set_during_marking(false);
910 }
911
912 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
913 double end_time_sec = os::elapsedTime();
914 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
915 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
916 _cur_mark_stop_world_time_ms += elapsed_time_ms;
917 _prev_collection_pause_end_ms += elapsed_time_ms;
918
919 record_pause(Remark, _mark_remark_start_sec, end_time_sec);
920 }
921
922 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
923 _mark_cleanup_start_sec = os::elapsedTime();
924 }
925
926 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
927 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
928 "skip last young-only gc");
929 collector_state()->set_last_young_gc(should_continue_with_reclaim);
930 // We skip the marking phase.
931 if (!should_continue_with_reclaim) {
932 abort_time_to_mixed_tracking();
933 }
934 collector_state()->set_in_marking_window(false);
935 }
936
937 void G1CollectorPolicy::record_concurrent_pause() {
938 if (_stop_world_start > 0.0) {
939 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
940 _trace_young_gen_time_data.record_yield_time(yield_ms);
941 }
942 }
943
944 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
945 return phase_times()->average_time_ms(phase);
946 }
947
948 double G1CollectorPolicy::young_other_time_ms() const {
949 return phase_times()->young_cset_choice_time_ms() +
950 phase_times()->young_free_cset_time_ms();
951 }
952
953 double G1CollectorPolicy::non_young_other_time_ms() const {
954 return phase_times()->non_young_cset_choice_time_ms() +
955 phase_times()->non_young_free_cset_time_ms();
956
957 }
958
959 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
960 return pause_time_ms -
961 average_time_ms(G1GCPhaseTimes::UpdateRS) -
962 average_time_ms(G1GCPhaseTimes::ScanRS) -
963 average_time_ms(G1GCPhaseTimes::ObjCopy) -
964 average_time_ms(G1GCPhaseTimes::Termination);
965 }
966
967 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
968 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
969 }
970
971 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
972 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
973 }
974
975 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
976 if (about_to_start_mixed_phase()) {
977 return false;
978 }
979
980 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
981
982 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
983 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
984 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
985
986 if (marking_request_bytes > marking_initiating_used_threshold) {
987 if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
988 ergo_verbose5(ErgoConcCycles,
989 "request concurrent cycle initiation",
990 ergo_format_reason("occupancy higher than threshold")
991 ergo_format_byte("occupancy")
992 ergo_format_byte("allocation request")
993 ergo_format_byte_perc("threshold")
994 ergo_format_str("source"),
995 cur_used_bytes,
996 alloc_byte_size,
997 marking_initiating_used_threshold,
998 (double) marking_initiating_used_threshold / _g1->capacity() * 100,
999 source);
1000 return true;
1001 } else {
1002 ergo_verbose5(ErgoConcCycles,
1003 "do not request concurrent cycle initiation",
1004 ergo_format_reason("still doing mixed collections")
1005 ergo_format_byte("occupancy")
1006 ergo_format_byte("allocation request")
1007 ergo_format_byte_perc("threshold")
1008 ergo_format_str("source"),
1009 cur_used_bytes,
1010 alloc_byte_size,
1011 marking_initiating_used_threshold,
1012 (double) InitiatingHeapOccupancyPercent,
1013 source);
1014 }
1015 }
1016
1017 return false;
1018 }
1019
1020 // Anything below that is considered to be zero
1021 #define MIN_TIMER_GRANULARITY 0.0000001
1022
1023 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
1024 double end_time_sec = os::elapsedTime();
1025 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1026 "otherwise, the subtraction below does not make sense");
1027 size_t cur_used_bytes = _g1->used();
1028 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1029 bool last_pause_included_initial_mark = false;
1030 bool update_stats = !_g1->evacuation_failed();
1031
1032 #ifndef PRODUCT
1033 if (G1YoungSurvRateVerbose) {
1034 gclog_or_tty->cr();
1035 _short_lived_surv_rate_group->print();
1036 // do that for any other surv rate groups too
1037 }
1038 #endif // PRODUCT
1039
1040 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
1041
1042 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1043 if (last_pause_included_initial_mark) {
1044 record_concurrent_mark_init_end(0.0);
1045 } else {
1046 maybe_start_marking();
1047 }
1048
1049 double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1050 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1051 // This usually happens due to the timer not having the required
1052 // granularity. Some Linuxes are the usual culprits.
1053 // We'll just set it to something (arbitrarily) small.
1054 app_time_ms = 1.0;
1055 }
1056
1057 if (update_stats) {
1058 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1059 // We maintain the invariant that all objects allocated by mutator
1060 // threads will be allocated out of eden regions. So, we can use
1061 // the eden region number allocated since the previous GC to
1062 // calculate the application's allocate rate. The only exception
1063 // to that is humongous objects that are allocated separately. But
1064 // given that humongous object allocations do not really affect
1065 // either the pause's duration nor when the next pause will take
1066 // place we can safely ignore them here.
1067 uint regions_allocated = eden_cset_region_length();
1068 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1069 _alloc_rate_ms_seq->add(alloc_rate_ms);
1070
1071 double interval_ms =
1072 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1073 update_recent_gc_times(end_time_sec, pause_time_ms);
1074 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1075 if (recent_avg_pause_time_ratio() < 0.0 ||
1076 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1077 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1078 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1079 if (_recent_avg_pause_time_ratio < 0.0) {
1080 _recent_avg_pause_time_ratio = 0.0;
1081 } else {
1082 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1083 _recent_avg_pause_time_ratio = 1.0;
1084 }
1085 }
1086 }
1087
1088 bool new_in_marking_window = collector_state()->in_marking_window();
1089 bool new_in_marking_window_im = false;
1090 if (last_pause_included_initial_mark) {
1091 new_in_marking_window = true;
1092 new_in_marking_window_im = true;
1093 }
1094
1095 if (collector_state()->last_young_gc()) {
1096 // This is supposed to to be the "last young GC" before we start
1097 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1098 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1099
1100 if (next_gc_should_be_mixed("start mixed GCs",
1101 "do not start mixed GCs")) {
1102 collector_state()->set_gcs_are_young(false);
1103 } else {
1104 // We aborted the mixed GC phase early.
1105 abort_time_to_mixed_tracking();
1106 }
1107
1108 collector_state()->set_last_young_gc(false);
1109 }
1110
1111 if (!collector_state()->last_gc_was_young()) {
1112 // This is a mixed GC. Here we decide whether to continue doing
1113 // mixed GCs or not.
1114 if (!next_gc_should_be_mixed("continue mixed GCs",
1115 "do not continue mixed GCs")) {
1116 collector_state()->set_gcs_are_young(true);
1117
1118 maybe_start_marking();
1119 }
1120 }
1121
1122 _short_lived_surv_rate_group->start_adding_regions();
1123 // Do that for any other surv rate groups
1124
1125 if (update_stats) {
1126 double cost_per_card_ms = 0.0;
1127 double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1128 if (_pending_cards > 0) {
1129 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1130 _cost_per_card_ms_seq->add(cost_per_card_ms);
1131 }
1132 _cost_scan_hcc_seq->add(cost_scan_hcc);
1133
1134 double cost_per_entry_ms = 0.0;
1135 if (cards_scanned > 10) {
1136 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1137 if (collector_state()->last_gc_was_young()) {
1138 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1139 } else {
1140 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1141 }
1142 }
1143
1144 if (_max_rs_lengths > 0) {
1145 double cards_per_entry_ratio =
1146 (double) cards_scanned / (double) _max_rs_lengths;
1147 if (collector_state()->last_gc_was_young()) {
1148 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1149 } else {
1150 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1151 }
1152 }
1153
1154 // This is defensive. For a while _max_rs_lengths could get
1155 // smaller than _recorded_rs_lengths which was causing
1156 // rs_length_diff to get very large and mess up the RSet length
1157 // predictions. The reason was unsafe concurrent updates to the
1158 // _inc_cset_recorded_rs_lengths field which the code below guards
1159 // against (see CR 7118202). This bug has now been fixed (see CR
1160 // 7119027). However, I'm still worried that
1161 // _inc_cset_recorded_rs_lengths might still end up somewhat
1162 // inaccurate. The concurrent refinement thread calculates an
1163 // RSet's length concurrently with other CR threads updating it
1164 // which might cause it to calculate the length incorrectly (if,
1165 // say, it's in mid-coarsening). So I'll leave in the defensive
1166 // conditional below just in case.
1167 size_t rs_length_diff = 0;
1168 if (_max_rs_lengths > _recorded_rs_lengths) {
1169 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1170 }
1171 _rs_length_diff_seq->add((double) rs_length_diff);
1172
1173 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1174 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1175 double cost_per_byte_ms = 0.0;
1176
1177 if (copied_bytes > 0) {
1178 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1179 if (collector_state()->in_marking_window()) {
1180 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1181 } else {
1182 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1183 }
1184 }
1185
1186 if (young_cset_region_length() > 0) {
1187 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1188 young_cset_region_length());
1189 }
1190
1191 if (old_cset_region_length() > 0) {
1192 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1193 old_cset_region_length());
1194 }
1195
1196 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1197
1198 _pending_cards_seq->add((double) _pending_cards);
1199 _rs_lengths_seq->add((double) _max_rs_lengths);
1200 }
1201
1202 collector_state()->set_in_marking_window(new_in_marking_window);
1203 collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1204 _free_regions_at_end_of_collection = _g1->num_free_regions();
1205 // IHOP control wants to know the expected young gen length if it were not
1206 // restrained by the heap reserve. Using the actual length would make the
1207 // prediction too small and the limit the young gen every time we get to the
1208 // predicted target occupancy.
1209 size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
1210 update_rs_lengths_prediction();
1211
1212 // Only update IHOP information on regular GCs.
1213 if (update_stats) {
1214 double marking_to_mixed_time = -1.0;
1215 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1216 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1217 assert(marking_to_mixed_time > 0.0,
1218 "Initial mark to mixed time must be larger than zero but is %.3f",
1219 marking_to_mixed_time);
1220 }
1221
1222 update_ihop_statistics(marking_to_mixed_time,
1223 app_time_ms / 1000.0,
1224 _last_old_allocated_bytes,
1225 last_unrestrained_young_length * HeapRegion::GrainBytes);
1226 }
1227 _last_old_allocated_bytes = 0;
1228
1229 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1230 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1231
1232 double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1233
1234 if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1235 ergo_verbose2(ErgoTiming,
1236 "adjust concurrent refinement thresholds",
1237 ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1238 ergo_format_ms("Update RS time goal")
1239 ergo_format_ms("Scan HCC time"),
1240 update_rs_time_goal_ms,
1241 scan_hcc_time_ms);
1242
1243 update_rs_time_goal_ms = 0;
1244 } else {
1245 update_rs_time_goal_ms -= scan_hcc_time_ms;
1246 }
1247 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1248 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1249 update_rs_time_goal_ms);
1250
1251 _collectionSetChooser->verify();
1252 }
1253
1254 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1255 if (G1UseAdaptiveIHOP) {
1256 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1257 G1CollectedHeap::heap()->max_capacity(),
1258 &_predictor,
1259 G1ReservePercent,
1260 G1HeapWastePercent);
1261 } else {
1262 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1263 G1CollectedHeap::heap()->max_capacity());
1264 }
1265 }
1266
1267 void G1CollectorPolicy::update_ihop_statistics(double marking_time,
1268 double mutator_time_s,
1269 size_t mutator_alloc_bytes,
1270 size_t young_gen_size) {
1271 bool report = false;
1272
1273 // To avoid using really small times that may be caused by e.g. back-to-back gcs
1274 // we filter them out.
1275 double const min_valid_time = 1e-6;
1276
1277 if (marking_time > min_valid_time) {
1278 _ihop_control->update_marking_length(marking_time);
1279 report = true;
1280 }
1281
1282 // As an approximation for the young gc promotion rates during marking we use
1283 // all of them. In many applications there are only a few if any young gcs during
1284 // marking, which makes any prediction useless. This increases the accuracy of the
1285 // prediction.
1286 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1287 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1288 report = true;
1289 }
1290
1291 if (report) {
1292 report_ihop_statistics();
1293 }
1294 }
1295
1296 void G1CollectorPolicy::report_ihop_statistics() {
1297 _ihop_control->print();
1298 }
1299
1300 #define EXT_SIZE_FORMAT "%.1f%s"
1301 #define EXT_SIZE_PARAMS(bytes) \
1302 byte_size_in_proper_unit((double)(bytes)), \
1303 proper_unit_for_byte_size((bytes))
1304
1305 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1306 YoungList* young_list = _g1->young_list();
1307 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1308 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1309 _heap_capacity_bytes_before_gc = _g1->capacity();
1310 _heap_used_bytes_before_gc = _g1->used();
1311 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1312
1313 _eden_capacity_bytes_before_gc =
1314 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1315
1316 if (full) {
1317 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1318 }
1319 }
1320
1321 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1322 size_t bytes_after = _g1->used();
1323 size_t capacity = _g1->capacity();
1324
1325 gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1326 byte_size_in_proper_unit(bytes_before),
1327 proper_unit_for_byte_size(bytes_before),
1328 byte_size_in_proper_unit(bytes_after),
1329 proper_unit_for_byte_size(bytes_after),
1330 byte_size_in_proper_unit(capacity),
1331 proper_unit_for_byte_size(capacity));
1332 }
1333
1334 void G1CollectorPolicy::print_heap_transition() const {
1335 print_heap_transition(_heap_used_bytes_before_gc);
1336 }
1337
1338 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1339 YoungList* young_list = _g1->young_list();
1340
1341 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1342 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1343 size_t heap_used_bytes_after_gc = _g1->used();
1344
1345 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1346 size_t eden_capacity_bytes_after_gc =
1347 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1348
1349 gclog_or_tty->print(
1350 " [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1351 "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1352 "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1353 EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1354 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1355 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1356 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1357 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1358 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1359 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1360 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1361 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1362 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1363 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1364
1365 if (full) {
1366 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1367 }
1368
1369 gclog_or_tty->cr();
1370 }
1371
1372 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1373 phase_times()->print(pause_time_sec);
1374 }
1375
1376 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1377 double update_rs_processed_buffers,
1378 double goal_ms) {
1379 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1380 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1381
1382 if (G1UseAdaptiveConcRefinement) {
1383 const int k_gy = 3, k_gr = 6;
1384 const double inc_k = 1.1, dec_k = 0.9;
1385
1386 int g = cg1r->green_zone();
1387 if (update_rs_time > goal_ms) {
1388 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1389 } else {
1390 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1391 g = (int)MAX2(g * inc_k, g + 1.0);
1392 }
1393 }
1394 // Change the refinement threads params
1395 cg1r->set_green_zone(g);
1396 cg1r->set_yellow_zone(g * k_gy);
1397 cg1r->set_red_zone(g * k_gr);
1398 cg1r->reinitialize_threads();
1399
1400 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1401 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1402 cg1r->yellow_zone());
1403 // Change the barrier params
1404 dcqs.set_process_completed_threshold(processing_threshold);
1405 dcqs.set_max_completed_queue(cg1r->red_zone());
1406 }
1407
1408 int curr_queue_size = dcqs.completed_buffers_num();
1409 if (curr_queue_size >= cg1r->yellow_zone()) {
1410 dcqs.set_completed_queue_padding(curr_queue_size);
1411 } else {
1412 dcqs.set_completed_queue_padding(0);
1413 }
1414 dcqs.notify_if_necessary();
1415 }
1416
1417 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1418 return (size_t) get_new_prediction(_rs_length_diff_seq);
1419 }
1420
1421 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1422 return get_new_prediction(_alloc_rate_ms_seq);
1423 }
1424
1425 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1426 return get_new_prediction(_cost_per_card_ms_seq);
1427 }
1428
1429 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1430 return get_new_prediction(_cost_scan_hcc_seq);
1431 }
1432
1433 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1434 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1435 }
1436
1437 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1438 return get_new_prediction(_young_cards_per_entry_ratio_seq);
1439 }
1440
1441 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1442 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1443 return predict_young_cards_per_entry_ratio();
1444 } else {
1445 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1446 }
1447 }
1448
1449 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1450 return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1451 }
1452
1453 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1454 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1455 }
1456
1457 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1458 if (collector_state()->gcs_are_young()) {
1459 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1460 } else {
1461 return predict_mixed_rs_scan_time_ms(card_num);
1462 }
1463 }
1464
1465 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1466 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1467 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1468 } else {
1469 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1470 }
1471 }
1472
1473 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1474 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1475 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1476 } else {
1477 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1478 }
1479 }
1480
1481 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1482 if (collector_state()->during_concurrent_mark()) {
1483 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1484 } else {
1485 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1486 }
1487 }
1488
1489 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1490 return get_new_prediction(_constant_other_time_ms_seq);
1491 }
1492
1493 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1494 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1495 }
1496
1497 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1498 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1499 }
1500
1501 double G1CollectorPolicy::predict_remark_time_ms() const {
1502 return get_new_prediction(_concurrent_mark_remark_times_ms);
1503 }
1504
1505 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1506 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1507 }
1508
1509 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1510 TruncatedSeq* seq = surv_rate_group->get_seq(age);
1511 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1512 double pred = get_new_prediction(seq);
1513 if (pred > 1.0) {
1514 pred = 1.0;
1515 }
1516 return pred;
1517 }
1518
1519 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1520 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1521 }
1522
1523 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1524 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1525 }
1526
1527 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1528 size_t scanned_cards) const {
1529 return
1530 predict_rs_update_time_ms(pending_cards) +
1531 predict_rs_scan_time_ms(scanned_cards) +
1532 predict_constant_other_time_ms();
1533 }
1534
1535 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1536 size_t rs_length = predict_rs_length_diff();
1537 size_t card_num;
1538 if (collector_state()->gcs_are_young()) {
1539 card_num = predict_young_card_num(rs_length);
1540 } else {
1541 card_num = predict_non_young_card_num(rs_length);
1542 }
1543 return predict_base_elapsed_time_ms(pending_cards, card_num);
1544 }
1545
1546 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1547 size_t bytes_to_copy;
1548 if (hr->is_marked())
1549 bytes_to_copy = hr->max_live_bytes();
1550 else {
1551 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1552 int age = hr->age_in_surv_rate_group();
1553 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1554 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1555 }
1556 return bytes_to_copy;
1557 }
1558
1559 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1560 bool for_young_gc) const {
1561 size_t rs_length = hr->rem_set()->occupied();
1562 size_t card_num;
1563
1564 // Predicting the number of cards is based on which type of GC
1565 // we're predicting for.
1566 if (for_young_gc) {
1567 card_num = predict_young_card_num(rs_length);
1568 } else {
1569 card_num = predict_non_young_card_num(rs_length);
1570 }
1571 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1572
1573 double region_elapsed_time_ms =
1574 predict_rs_scan_time_ms(card_num) +
1575 predict_object_copy_time_ms(bytes_to_copy);
1576
1577 // The prediction of the "other" time for this region is based
1578 // upon the region type and NOT the GC type.
1579 if (hr->is_young()) {
1580 region_elapsed_time_ms += predict_young_other_time_ms(1);
1581 } else {
1582 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1583 }
1584 return region_elapsed_time_ms;
1585 }
1586
1587 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1588 uint survivor_cset_region_length) {
1589 _eden_cset_region_length = eden_cset_region_length;
1590 _survivor_cset_region_length = survivor_cset_region_length;
1591 _old_cset_region_length = 0;
1592 }
1593
1594 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1595 _recorded_rs_lengths = rs_lengths;
1596 }
1597
1598 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1599 double elapsed_ms) {
1600 _recent_gc_times_ms->add(elapsed_ms);
1601 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1602 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1603 }
1604
1605 size_t G1CollectorPolicy::expansion_amount() const {
1606 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1607 double threshold = _gc_overhead_perc;
1608 if (recent_gc_overhead > threshold) {
1609 // We will double the existing space, or take
1610 // G1ExpandByPercentOfAvailable % of the available expansion
1611 // space, whichever is smaller, bounded below by a minimum
1612 // expansion (unless that's all that's left.)
1613 const size_t min_expand_bytes = 1*M;
1614 size_t reserved_bytes = _g1->max_capacity();
1615 size_t committed_bytes = _g1->capacity();
1616 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1617 size_t expand_bytes;
1618 size_t expand_bytes_via_pct =
1619 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1620 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1621 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1622 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1623
1624 ergo_verbose5(ErgoHeapSizing,
1625 "attempt heap expansion",
1626 ergo_format_reason("recent GC overhead higher than "
1627 "threshold after GC")
1628 ergo_format_perc("recent GC overhead")
1629 ergo_format_perc("threshold")
1630 ergo_format_byte("uncommitted")
1631 ergo_format_byte_perc("calculated expansion amount"),
1632 recent_gc_overhead, threshold,
1633 uncommitted_bytes,
1634 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1635
1636 return expand_bytes;
1637 } else {
1638 return 0;
1639 }
1640 }
1641
1642 void G1CollectorPolicy::print_tracing_info() const {
1643 _trace_young_gen_time_data.print();
1644 _trace_old_gen_time_data.print();
1645 }
1646
1647 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1648 #ifndef PRODUCT
1649 _short_lived_surv_rate_group->print_surv_rate_summary();
1650 // add this call for any other surv rate groups
1651 #endif // PRODUCT
1652 }
1653
1654 bool G1CollectorPolicy::is_young_list_full() const {
1655 uint young_list_length = _g1->young_list()->length();
1656 uint young_list_target_length = _young_list_target_length;
1657 return young_list_length >= young_list_target_length;
1658 }
1659
1660 bool G1CollectorPolicy::can_expand_young_list() const {
1661 uint young_list_length = _g1->young_list()->length();
1662 uint young_list_max_length = _young_list_max_length;
1663 return young_list_length < young_list_max_length;
1664 }
1665
1666 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1667 uint expansion_region_num = 0;
1668 if (GCLockerEdenExpansionPercent > 0) {
1669 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1670 double expansion_region_num_d = perc * (double) _young_list_target_length;
1671 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1672 // less than 1.0) we'll get 1.
1673 expansion_region_num = (uint) ceil(expansion_region_num_d);
1674 } else {
1675 assert(expansion_region_num == 0, "sanity");
1676 }
1677 _young_list_max_length = _young_list_target_length + expansion_region_num;
1678 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1679 }
1680
1681 // Calculates survivor space parameters.
1682 void G1CollectorPolicy::update_survivors_policy() {
1683 double max_survivor_regions_d =
1684 (double) _young_list_target_length / (double) SurvivorRatio;
1685 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1686 // smaller than 1.0) we'll get 1.
1687 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1688
1689 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1690 HeapRegion::GrainWords * _max_survivor_regions, counters());
1691 }
1692
1693 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1694 // We actually check whether we are marking here and not if we are in a
1695 // reclamation phase. This means that we will schedule a concurrent mark
1696 // even while we are still in the process of reclaiming memory.
1697 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1698 if (!during_cycle) {
1699 ergo_verbose1(ErgoConcCycles,
1700 "request concurrent cycle initiation",
1701 ergo_format_reason("requested by GC cause")
1702 ergo_format_str("GC cause"),
1703 GCCause::to_string(gc_cause));
1704 collector_state()->set_initiate_conc_mark_if_possible(true);
1705 return true;
1706 } else {
1707 ergo_verbose1(ErgoConcCycles,
1708 "do not request concurrent cycle initiation",
1709 ergo_format_reason("concurrent cycle already in progress")
1710 ergo_format_str("GC cause"),
1711 GCCause::to_string(gc_cause));
1712 return false;
1713 }
1714 }
1715
1716 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1717 // We are about to decide on whether this pause will be an
1718 // initial-mark pause.
1719
1720 // First, collector_state()->during_initial_mark_pause() should not be already set. We
1721 // will set it here if we have to. However, it should be cleared by
1722 // the end of the pause (it's only set for the duration of an
1723 // initial-mark pause).
1724 assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1725
1726 if (collector_state()->initiate_conc_mark_if_possible()) {
1727 // We had noticed on a previous pause that the heap occupancy has
1728 // gone over the initiating threshold and we should start a
1729 // concurrent marking cycle. So we might initiate one.
1730
1731 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1732 // Initiate a new initial mark only if there is no marking or reclamation going
1733 // on.
1734
1735 collector_state()->set_during_initial_mark_pause(true);
1736 // And we can now clear initiate_conc_mark_if_possible() as
1737 // we've already acted on it.
1738 collector_state()->set_initiate_conc_mark_if_possible(false);
1739
1740 ergo_verbose0(ErgoConcCycles,
1741 "initiate concurrent cycle",
1742 ergo_format_reason("concurrent cycle initiation requested"));
1743 } else {
1744 // The concurrent marking thread is still finishing up the
1745 // previous cycle. If we start one right now the two cycles
1746 // overlap. In particular, the concurrent marking thread might
1747 // be in the process of clearing the next marking bitmap (which
1748 // we will use for the next cycle if we start one). Starting a
1749 // cycle now will be bad given that parts of the marking
1750 // information might get cleared by the marking thread. And we
1751 // cannot wait for the marking thread to finish the cycle as it
1752 // periodically yields while clearing the next marking bitmap
1753 // and, if it's in a yield point, it's waiting for us to
1754 // finish. So, at this point we will not start a cycle and we'll
1755 // let the concurrent marking thread complete the last one.
1756 ergo_verbose0(ErgoConcCycles,
1757 "do not initiate concurrent cycle",
1758 ergo_format_reason("concurrent cycle already in progress"));
1759 }
1760 }
1761 }
1762
1763 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1764 G1CollectedHeap* _g1h;
1765 CSetChooserParUpdater _cset_updater;
1766
1767 public:
1768 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1769 uint chunk_size) :
1770 _g1h(G1CollectedHeap::heap()),
1771 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1772
1773 bool doHeapRegion(HeapRegion* r) {
1774 // Do we have any marking information for this region?
1775 if (r->is_marked()) {
1776 // We will skip any region that's currently used as an old GC
1777 // alloc region (we should not consider those for collection
1778 // before we fill them up).
1779 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1780 _cset_updater.add_region(r);
1781 }
1782 }
1783 return false;
1784 }
1785 };
1786
1787 class ParKnownGarbageTask: public AbstractGangTask {
1788 CollectionSetChooser* _hrSorted;
1789 uint _chunk_size;
1790 G1CollectedHeap* _g1;
1791 HeapRegionClaimer _hrclaimer;
1792
1793 public:
1794 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1795 AbstractGangTask("ParKnownGarbageTask"),
1796 _hrSorted(hrSorted), _chunk_size(chunk_size),
1797 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1798
1799 void work(uint worker_id) {
1800 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1801 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1802 }
1803 };
1804
1805 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1806 assert(n_workers > 0, "Active gc workers should be greater than 0");
1807 const uint overpartition_factor = 4;
1808 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1809 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1810 }
1811
1812 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1813 _collectionSetChooser->clear();
1814
1815 WorkGang* workers = _g1->workers();
1816 uint n_workers = workers->active_workers();
1817
1818 uint n_regions = _g1->num_regions();
1819 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1820 _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1821 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1822 workers->run_task(&par_known_garbage_task);
1823
1824 _collectionSetChooser->sort_regions();
1825
1826 double end_sec = os::elapsedTime();
1827 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1828 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1829 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1830 _prev_collection_pause_end_ms += elapsed_time_ms;
1831
1832 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1833 }
1834
1835 // Add the heap region at the head of the non-incremental collection set
1836 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1837 assert(_inc_cset_build_state == Active, "Precondition");
1838 assert(hr->is_old(), "the region should be old");
1839
1840 assert(!hr->in_collection_set(), "should not already be in the CSet");
1841 _g1->register_old_region_with_cset(hr);
1842 hr->set_next_in_collection_set(_collection_set);
1843 _collection_set = hr;
1844 _collection_set_bytes_used_before += hr->used();
1845 size_t rs_length = hr->rem_set()->occupied();
1846 _recorded_rs_lengths += rs_length;
1847 _old_cset_region_length += 1;
1848 }
1849
1850 // Initialize the per-collection-set information
1851 void G1CollectorPolicy::start_incremental_cset_building() {
1852 assert(_inc_cset_build_state == Inactive, "Precondition");
1853
1854 _inc_cset_head = NULL;
1855 _inc_cset_tail = NULL;
1856 _inc_cset_bytes_used_before = 0;
1857
1858 _inc_cset_max_finger = 0;
1859 _inc_cset_recorded_rs_lengths = 0;
1860 _inc_cset_recorded_rs_lengths_diffs = 0;
1861 _inc_cset_predicted_elapsed_time_ms = 0.0;
1862 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1863 _inc_cset_build_state = Active;
1864 }
1865
1866 void G1CollectorPolicy::finalize_incremental_cset_building() {
1867 assert(_inc_cset_build_state == Active, "Precondition");
1868 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1869
1870 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1871 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1872 // that adds a new region to the CSet. Further updates by the
1873 // concurrent refinement thread that samples the young RSet lengths
1874 // are accumulated in the *_diffs fields. Here we add the diffs to
1875 // the "main" fields.
1876
1877 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1878 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1879 } else {
1880 // This is defensive. The diff should in theory be always positive
1881 // as RSets can only grow between GCs. However, given that we
1882 // sample their size concurrently with other threads updating them
1883 // it's possible that we might get the wrong size back, which
1884 // could make the calculations somewhat inaccurate.
1885 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1886 if (_inc_cset_recorded_rs_lengths >= diffs) {
1887 _inc_cset_recorded_rs_lengths -= diffs;
1888 } else {
1889 _inc_cset_recorded_rs_lengths = 0;
1890 }
1891 }
1892 _inc_cset_predicted_elapsed_time_ms +=
1893 _inc_cset_predicted_elapsed_time_ms_diffs;
1894
1895 _inc_cset_recorded_rs_lengths_diffs = 0;
1896 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1897 }
1898
1899 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1900 // This routine is used when:
1901 // * adding survivor regions to the incremental cset at the end of an
1902 // evacuation pause,
1903 // * adding the current allocation region to the incremental cset
1904 // when it is retired, and
1905 // * updating existing policy information for a region in the
1906 // incremental cset via young list RSet sampling.
1907 // Therefore this routine may be called at a safepoint by the
1908 // VM thread, or in-between safepoints by mutator threads (when
1909 // retiring the current allocation region) or a concurrent
1910 // refine thread (RSet sampling).
1911
1912 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1913 size_t used_bytes = hr->used();
1914 _inc_cset_recorded_rs_lengths += rs_length;
1915 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1916 _inc_cset_bytes_used_before += used_bytes;
1917
1918 // Cache the values we have added to the aggregated information
1919 // in the heap region in case we have to remove this region from
1920 // the incremental collection set, or it is updated by the
1921 // rset sampling code
1922 hr->set_recorded_rs_length(rs_length);
1923 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1924 }
1925
1926 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1927 size_t new_rs_length) {
1928 // Update the CSet information that is dependent on the new RS length
1929 assert(hr->is_young(), "Precondition");
1930 assert(!SafepointSynchronize::is_at_safepoint(),
1931 "should not be at a safepoint");
1932
1933 // We could have updated _inc_cset_recorded_rs_lengths and
1934 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1935 // that atomically, as this code is executed by a concurrent
1936 // refinement thread, potentially concurrently with a mutator thread
1937 // allocating a new region and also updating the same fields. To
1938 // avoid the atomic operations we accumulate these updates on two
1939 // separate fields (*_diffs) and we'll just add them to the "main"
1940 // fields at the start of a GC.
1941
1942 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1943 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1944 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1945
1946 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1947 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1948 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1949 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1950
1951 hr->set_recorded_rs_length(new_rs_length);
1952 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1953 }
1954
1955 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1956 assert(hr->is_young(), "invariant");
1957 assert(hr->young_index_in_cset() > -1, "should have already been set");
1958 assert(_inc_cset_build_state == Active, "Precondition");
1959
1960 // We need to clear and set the cached recorded/cached collection set
1961 // information in the heap region here (before the region gets added
1962 // to the collection set). An individual heap region's cached values
1963 // are calculated, aggregated with the policy collection set info,
1964 // and cached in the heap region here (initially) and (subsequently)
1965 // by the Young List sampling code.
1966
1967 size_t rs_length = hr->rem_set()->occupied();
1968 add_to_incremental_cset_info(hr, rs_length);
1969
1970 HeapWord* hr_end = hr->end();
1971 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1972
1973 assert(!hr->in_collection_set(), "invariant");
1974 _g1->register_young_region_with_cset(hr);
1975 assert(hr->next_in_collection_set() == NULL, "invariant");
1976 }
1977
1978 // Add the region at the RHS of the incremental cset
1979 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1980 // We should only ever be appending survivors at the end of a pause
1981 assert(hr->is_survivor(), "Logic");
1982
1983 // Do the 'common' stuff
1984 add_region_to_incremental_cset_common(hr);
1985
1986 // Now add the region at the right hand side
1987 if (_inc_cset_tail == NULL) {
1988 assert(_inc_cset_head == NULL, "invariant");
1989 _inc_cset_head = hr;
1990 } else {
1991 _inc_cset_tail->set_next_in_collection_set(hr);
1992 }
1993 _inc_cset_tail = hr;
1994 }
1995
1996 // Add the region to the LHS of the incremental cset
1997 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1998 // Survivors should be added to the RHS at the end of a pause
1999 assert(hr->is_eden(), "Logic");
2000
2001 // Do the 'common' stuff
2002 add_region_to_incremental_cset_common(hr);
2003
2004 // Add the region at the left hand side
2005 hr->set_next_in_collection_set(_inc_cset_head);
2006 if (_inc_cset_head == NULL) {
2007 assert(_inc_cset_tail == NULL, "Invariant");
2008 _inc_cset_tail = hr;
2009 }
2010 _inc_cset_head = hr;
2011 }
2012
2013 #ifndef PRODUCT
2014 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2015 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2016
2017 st->print_cr("\nCollection_set:");
2018 HeapRegion* csr = list_head;
2019 while (csr != NULL) {
2020 HeapRegion* next = csr->next_in_collection_set();
2021 assert(csr->in_collection_set(), "bad CS");
2022 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2023 HR_FORMAT_PARAMS(csr),
2024 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2025 csr->age_in_surv_rate_group_cond());
2026 csr = next;
2027 }
2028 }
2029 #endif // !PRODUCT
2030
2031 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2032 // Returns the given amount of reclaimable bytes (that represents
2033 // the amount of reclaimable space still to be collected) as a
2034 // percentage of the current heap capacity.
2035 size_t capacity_bytes = _g1->capacity();
2036 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2037 }
2038
2039 void G1CollectorPolicy::maybe_start_marking() {
2040 if (need_to_start_conc_mark("end of GC")) {
2041 // Note: this might have already been set, if during the last
2042 // pause we decided to start a cycle but at the beginning of
2043 // this pause we decided to postpone it. That's OK.
2044 collector_state()->set_initiate_conc_mark_if_possible(true);
2045 }
2046 }
2047
2048 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2049 assert(!collector_state()->full_collection(), "must be");
2050 if (collector_state()->during_initial_mark_pause()) {
2051 assert(collector_state()->last_gc_was_young(), "must be");
2052 assert(!collector_state()->last_young_gc(), "must be");
2053 return InitialMarkGC;
2054 } else if (collector_state()->last_young_gc()) {
2055 assert(!collector_state()->during_initial_mark_pause(), "must be");
2056 assert(collector_state()->last_gc_was_young(), "must be");
2057 return LastYoungGC;
2058 } else if (!collector_state()->last_gc_was_young()) {
2059 assert(!collector_state()->during_initial_mark_pause(), "must be");
2060 assert(!collector_state()->last_young_gc(), "must be");
2061 return MixedGC;
2062 } else {
2063 assert(collector_state()->last_gc_was_young(), "must be");
2064 assert(!collector_state()->during_initial_mark_pause(), "must be");
2065 assert(!collector_state()->last_young_gc(), "must be");
2066 return YoungOnlyGC;
2067 }
2068 }
2069
2070 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2071 // Manage the MMU tracker. For some reason it ignores Full GCs.
2072 if (kind != FullGC) {
2073 _mmu_tracker->add_pause(start, end);
2074 }
2075 // Manage the mutator time tracking from initial mark to first mixed gc.
2076 switch (kind) {
2077 case FullGC:
2078 abort_time_to_mixed_tracking();
2079 break;
2080 case Cleanup:
2081 case Remark:
2082 case YoungOnlyGC:
2083 case LastYoungGC:
2084 _initial_mark_to_mixed.add_pause(end - start);
2085 break;
2086 case InitialMarkGC:
2087 _initial_mark_to_mixed.record_initial_mark_end(end);
2088 break;
2089 case MixedGC:
2090 _initial_mark_to_mixed.record_mixed_gc_start(start);
2091 break;
2092 default:
2093 ShouldNotReachHere();
2094 }
2095 }
2096
2097 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2098 _initial_mark_to_mixed.reset();
2099 }
2100
2101 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2102 const char* false_action_str) const {
2103 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2104 if (cset_chooser->is_empty()) {
2105 ergo_verbose0(ErgoMixedGCs,
2106 false_action_str,
2107 ergo_format_reason("candidate old regions not available"));
2108 return false;
2109 }
2110
2111 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2112 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2113 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2114 double threshold = (double) G1HeapWastePercent;
2115 if (reclaimable_perc <= threshold) {
2116 ergo_verbose4(ErgoMixedGCs,
2117 false_action_str,
2118 ergo_format_reason("reclaimable percentage not over threshold")
2119 ergo_format_region("candidate old regions")
2120 ergo_format_byte_perc("reclaimable")
2121 ergo_format_perc("threshold"),
2122 cset_chooser->remaining_regions(),
2123 reclaimable_bytes,
2124 reclaimable_perc, threshold);
2125 return false;
2126 }
2127
2128 ergo_verbose4(ErgoMixedGCs,
2129 true_action_str,
2130 ergo_format_reason("candidate old regions available")
2131 ergo_format_region("candidate old regions")
2132 ergo_format_byte_perc("reclaimable")
2133 ergo_format_perc("threshold"),
2134 cset_chooser->remaining_regions(),
2135 reclaimable_bytes,
2136 reclaimable_perc, threshold);
2137 return true;
2138 }
2139
2140 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2141 // The min old CSet region bound is based on the maximum desired
2142 // number of mixed GCs after a cycle. I.e., even if some old regions
2143 // look expensive, we should add them to the CSet anyway to make
2144 // sure we go through the available old regions in no more than the
2145 // maximum desired number of mixed GCs.
2146 //
2147 // The calculation is based on the number of marked regions we added
2148 // to the CSet chooser in the first place, not how many remain, so
2149 // that the result is the same during all mixed GCs that follow a cycle.
2150
2151 const size_t region_num = (size_t) _collectionSetChooser->length();
2152 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2153 size_t result = region_num / gc_num;
2154 // emulate ceiling
2155 if (result * gc_num < region_num) {
2156 result += 1;
2157 }
2158 return (uint) result;
2159 }
2160
2161 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2162 // The max old CSet region bound is based on the threshold expressed
2163 // as a percentage of the heap size. I.e., it should bound the
2164 // number of old regions added to the CSet irrespective of how many
2165 // of them are available.
2166
2167 const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2168 const size_t region_num = g1h->num_regions();
2169 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2170 size_t result = region_num * perc / 100;
2171 // emulate ceiling
2172 if (100 * result < region_num * perc) {
2173 result += 1;
2174 }
2175 return (uint) result;
2176 }
2177
2178
2179 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2180 double young_start_time_sec = os::elapsedTime();
2181
2182 YoungList* young_list = _g1->young_list();
2183 finalize_incremental_cset_building();
2184
2185 guarantee(target_pause_time_ms > 0.0,
2186 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2187 guarantee(_collection_set == NULL, "Precondition");
2188
2189 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2190 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2191
2192 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2193 "start choosing CSet",
2194 ergo_format_size("_pending_cards")
2195 ergo_format_ms("predicted base time")
2196 ergo_format_ms("remaining time")
2197 ergo_format_ms("target pause time"),
2198 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2199
2200 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2201
2202 if (collector_state()->last_gc_was_young()) {
2203 _trace_young_gen_time_data.increment_young_collection_count();
2204 } else {
2205 _trace_young_gen_time_data.increment_mixed_collection_count();
2206 }
2207
2208 // The young list is laid with the survivor regions from the previous
2209 // pause are appended to the RHS of the young list, i.e.
2210 // [Newly Young Regions ++ Survivors from last pause].
2211
2212 uint survivor_region_length = young_list->survivor_length();
2213 uint eden_region_length = young_list->eden_length();
2214 init_cset_region_lengths(eden_region_length, survivor_region_length);
2215
2216 HeapRegion* hr = young_list->first_survivor_region();
2217 while (hr != NULL) {
2218 assert(hr->is_survivor(), "badly formed young list");
2219 // There is a convention that all the young regions in the CSet
2220 // are tagged as "eden", so we do this for the survivors here. We
2221 // use the special set_eden_pre_gc() as it doesn't check that the
2222 // region is free (which is not the case here).
2223 hr->set_eden_pre_gc();
2224 hr = hr->get_next_young_region();
2225 }
2226
2227 // Clear the fields that point to the survivor list - they are all young now.
2228 young_list->clear_survivors();
2229
2230 _collection_set = _inc_cset_head;
2231 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2232 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2233
2234 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2235 "add young regions to CSet",
2236 ergo_format_region("eden")
2237 ergo_format_region("survivors")
2238 ergo_format_ms("predicted young region time")
2239 ergo_format_ms("target pause time"),
2240 eden_region_length, survivor_region_length,
2241 _inc_cset_predicted_elapsed_time_ms,
2242 target_pause_time_ms);
2243
2244 // The number of recorded young regions is the incremental
2245 // collection set's current size
2246 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2247
2248 double young_end_time_sec = os::elapsedTime();
2249 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2250
2251 return time_remaining_ms;
2252 }
2253
2254 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2255 double non_young_start_time_sec = os::elapsedTime();
2256 double predicted_old_time_ms = 0.0;
2257
2258
2259 if (!collector_state()->gcs_are_young()) {
2260 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2261 cset_chooser->verify();
2262 const uint min_old_cset_length = calc_min_old_cset_length();
2263 const uint max_old_cset_length = calc_max_old_cset_length();
2264
2265 uint expensive_region_num = 0;
2266 bool check_time_remaining = adaptive_young_list_length();
2267
2268 HeapRegion* hr = cset_chooser->peek();
2269 while (hr != NULL) {
2270 if (old_cset_region_length() >= max_old_cset_length) {
2271 // Added maximum number of old regions to the CSet.
2272 ergo_verbose2(ErgoCSetConstruction,
2273 "finish adding old regions to CSet",
2274 ergo_format_reason("old CSet region num reached max")
2275 ergo_format_region("old")
2276 ergo_format_region("max"),
2277 old_cset_region_length(), max_old_cset_length);
2278 break;
2279 }
2280
2281
2282 // Stop adding regions if the remaining reclaimable space is
2283 // not above G1HeapWastePercent.
2284 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2285 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2286 double threshold = (double) G1HeapWastePercent;
2287 if (reclaimable_perc <= threshold) {
2288 // We've added enough old regions that the amount of uncollected
2289 // reclaimable space is at or below the waste threshold. Stop
2290 // adding old regions to the CSet.
2291 ergo_verbose5(ErgoCSetConstruction,
2292 "finish adding old regions to CSet",
2293 ergo_format_reason("reclaimable percentage not over threshold")
2294 ergo_format_region("old")
2295 ergo_format_region("max")
2296 ergo_format_byte_perc("reclaimable")
2297 ergo_format_perc("threshold"),
2298 old_cset_region_length(),
2299 max_old_cset_length,
2300 reclaimable_bytes,
2301 reclaimable_perc, threshold);
2302 break;
2303 }
2304
2305 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2306 if (check_time_remaining) {
2307 if (predicted_time_ms > time_remaining_ms) {
2308 // Too expensive for the current CSet.
2309
2310 if (old_cset_region_length() >= min_old_cset_length) {
2311 // We have added the minimum number of old regions to the CSet,
2312 // we are done with this CSet.
2313 ergo_verbose4(ErgoCSetConstruction,
2314 "finish adding old regions to CSet",
2315 ergo_format_reason("predicted time is too high")
2316 ergo_format_ms("predicted time")
2317 ergo_format_ms("remaining time")
2318 ergo_format_region("old")
2319 ergo_format_region("min"),
2320 predicted_time_ms, time_remaining_ms,
2321 old_cset_region_length(), min_old_cset_length);
2322 break;
2323 }
2324
2325 // We'll add it anyway given that we haven't reached the
2326 // minimum number of old regions.
2327 expensive_region_num += 1;
2328 }
2329 } else {
2330 if (old_cset_region_length() >= min_old_cset_length) {
2331 // In the non-auto-tuning case, we'll finish adding regions
2332 // to the CSet if we reach the minimum.
2333 ergo_verbose2(ErgoCSetConstruction,
2334 "finish adding old regions to CSet",
2335 ergo_format_reason("old CSet region num reached min")
2336 ergo_format_region("old")
2337 ergo_format_region("min"),
2338 old_cset_region_length(), min_old_cset_length);
2339 break;
2340 }
2341 }
2342
2343 // We will add this region to the CSet.
2344 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2345 predicted_old_time_ms += predicted_time_ms;
2346 cset_chooser->pop(); // already have region via peek()
2347 _g1->old_set_remove(hr);
2348 add_old_region_to_cset(hr);
2349
2350 hr = cset_chooser->peek();
2351 }
2352 if (hr == NULL) {
2353 ergo_verbose0(ErgoCSetConstruction,
2354 "finish adding old regions to CSet",
2355 ergo_format_reason("candidate old regions not available"));
2356 }
2357
2358 if (expensive_region_num > 0) {
2359 // We print the information once here at the end, predicated on
2360 // whether we added any apparently expensive regions or not, to
2361 // avoid generating output per region.
2362 ergo_verbose4(ErgoCSetConstruction,
2363 "added expensive regions to CSet",
2364 ergo_format_reason("old CSet region num not reached min")
2365 ergo_format_region("old")
2366 ergo_format_region("expensive")
2367 ergo_format_region("min")
2368 ergo_format_ms("remaining time"),
2369 old_cset_region_length(),
2370 expensive_region_num,
2371 min_old_cset_length,
2372 time_remaining_ms);
2373 }
2374
2375 cset_chooser->verify();
2376 }
2377
2378 stop_incremental_cset_building();
2379
2380 ergo_verbose3(ErgoCSetConstruction,
2381 "finish choosing CSet",
2382 ergo_format_region("old")
2383 ergo_format_ms("predicted old region time")
2384 ergo_format_ms("time remaining"),
2385 old_cset_region_length(),
2386 predicted_old_time_ms, time_remaining_ms);
2387
2388 double non_young_end_time_sec = os::elapsedTime();
2389 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2390 }
2391
2392 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2393 if(TraceYoungGenTime) {
2394 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2395 }
2396 }
2397
2398 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2399 if(TraceYoungGenTime) {
2400 _all_yield_times_ms.add(yield_time_ms);
2401 }
2402 }
2403
2404 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2405 if(TraceYoungGenTime) {
2406 _total.add(pause_time_ms);
2407 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2408 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2409 _parallel.add(phase_times->cur_collection_par_time_ms());
2410 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2411 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2412 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2413 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2414 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2415 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2416
2417 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2418 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2419 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2420 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2421 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2422 phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2423
2424 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2425 _parallel_other.add(parallel_other_time);
2426 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2427 }
2428 }
2429
2430 void TraceYoungGenTimeData::increment_young_collection_count() {
2431 if(TraceYoungGenTime) {
2432 ++_young_pause_num;
2433 }
2434 }
2435
2436 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2437 if(TraceYoungGenTime) {
2438 ++_mixed_pause_num;
2439 }
2440 }
2441
2442 void TraceYoungGenTimeData::print_summary(const char* str,
2443 const NumberSeq* seq) const {
2444 double sum = seq->sum();
2445 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2446 str, sum / 1000.0, seq->avg());
2447 }
2448
2449 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2450 const NumberSeq* seq) const {
2451 print_summary(str, seq);
2452 gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2453 "(num", seq->num(), seq->sd(), seq->maximum());
2454 }
2455
2456 void TraceYoungGenTimeData::print() const {
2457 if (!TraceYoungGenTime) {
2458 return;
2459 }
2460
2461 gclog_or_tty->print_cr("ALL PAUSES");
2462 print_summary_sd(" Total", &_total);
2463 gclog_or_tty->cr();
2464 gclog_or_tty->cr();
2465 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2466 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2467 gclog_or_tty->cr();
2468
2469 gclog_or_tty->print_cr("EVACUATION PAUSES");
2470
2471 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2472 gclog_or_tty->print_cr("none");
2473 } else {
2474 print_summary_sd(" Evacuation Pauses", &_total);
2475 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2476 print_summary(" Parallel Time", &_parallel);
2477 print_summary(" Ext Root Scanning", &_ext_root_scan);
2478 print_summary(" SATB Filtering", &_satb_filtering);
2479 print_summary(" Update RS", &_update_rs);
2480 print_summary(" Scan RS", &_scan_rs);
2481 print_summary(" Object Copy", &_obj_copy);
2482 print_summary(" Termination", &_termination);
2483 print_summary(" Parallel Other", &_parallel_other);
2484 print_summary(" Clear CT", &_clear_ct);
2485 print_summary(" Other", &_other);
2486 }
2487 gclog_or_tty->cr();
2488
2489 gclog_or_tty->print_cr("MISC");
2490 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2491 print_summary_sd(" Yields", &_all_yield_times_ms);
2492 }
2493
2494 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2495 if (TraceOldGenTime) {
2496 _all_full_gc_times.add(full_gc_time_ms);
2497 }
2498 }
2499
2500 void TraceOldGenTimeData::print() const {
2501 if (!TraceOldGenTime) {
2502 return;
2503 }
2504
2505 if (_all_full_gc_times.num() > 0) {
2506 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2507 _all_full_gc_times.num(),
2508 _all_full_gc_times.sum() / 1000.0);
2509 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2510 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2511 _all_full_gc_times.sd(),
2512 _all_full_gc_times.maximum());
2513 }
2514 }