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 _bytes_allocated_in_old_since_last_gc(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 _cset_chooser = 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 cset_chooser()->clear();
858
859 _bytes_allocated_in_old_since_last_gc = 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 }
905
906 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
907 _mark_remark_start_sec = os::elapsedTime();
908 collector_state()->set_during_marking(false);
909 }
910
911 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
912 double end_time_sec = os::elapsedTime();
913 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
914 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
915 _prev_collection_pause_end_ms += elapsed_time_ms;
916
917 record_pause(Remark, _mark_remark_start_sec, end_time_sec);
918 }
919
920 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
921 _mark_cleanup_start_sec = os::elapsedTime();
922 }
923
924 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
925 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
926 "skip last young-only gc");
927 collector_state()->set_last_young_gc(should_continue_with_reclaim);
928 // We skip the marking phase.
929 if (!should_continue_with_reclaim) {
930 abort_time_to_mixed_tracking();
931 }
932 collector_state()->set_in_marking_window(false);
933 }
934
935 void G1CollectorPolicy::record_concurrent_pause() {
936 if (_stop_world_start > 0.0) {
937 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
938 _trace_young_gen_time_data.record_yield_time(yield_ms);
939 }
940 }
941
942 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
943 return phase_times()->average_time_ms(phase);
944 }
945
946 double G1CollectorPolicy::young_other_time_ms() const {
947 return phase_times()->young_cset_choice_time_ms() +
948 phase_times()->young_free_cset_time_ms();
949 }
950
951 double G1CollectorPolicy::non_young_other_time_ms() const {
952 return phase_times()->non_young_cset_choice_time_ms() +
953 phase_times()->non_young_free_cset_time_ms();
954
955 }
956
957 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
958 return pause_time_ms -
959 average_time_ms(G1GCPhaseTimes::UpdateRS) -
960 average_time_ms(G1GCPhaseTimes::ScanRS) -
961 average_time_ms(G1GCPhaseTimes::ObjCopy) -
962 average_time_ms(G1GCPhaseTimes::Termination);
963 }
964
965 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
966 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
967 }
968
969 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
970 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
971 }
972
973 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
974 if (about_to_start_mixed_phase()) {
975 return false;
976 }
977
978 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
979
980 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
981 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
982 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
983
984 if (marking_request_bytes > marking_initiating_used_threshold) {
985 if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
986 ergo_verbose5(ErgoConcCycles,
987 "request concurrent cycle initiation",
988 ergo_format_reason("occupancy higher than threshold")
989 ergo_format_byte("occupancy")
990 ergo_format_byte("allocation request")
991 ergo_format_byte_perc("threshold")
992 ergo_format_str("source"),
993 cur_used_bytes,
994 alloc_byte_size,
995 marking_initiating_used_threshold,
996 (double) marking_initiating_used_threshold / _g1->capacity() * 100,
997 source);
998 return true;
999 } else {
1000 ergo_verbose5(ErgoConcCycles,
1001 "do not request concurrent cycle initiation",
1002 ergo_format_reason("still doing mixed collections")
1003 ergo_format_byte("occupancy")
1004 ergo_format_byte("allocation request")
1005 ergo_format_byte_perc("threshold")
1006 ergo_format_str("source"),
1007 cur_used_bytes,
1008 alloc_byte_size,
1009 marking_initiating_used_threshold,
1010 (double) InitiatingHeapOccupancyPercent,
1011 source);
1012 }
1013 }
1014
1015 return false;
1016 }
1017
1018 // Anything below that is considered to be zero
1019 #define MIN_TIMER_GRANULARITY 0.0000001
1020
1021 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
1022 double end_time_sec = os::elapsedTime();
1023
1024 size_t cur_used_bytes = _g1->used();
1025 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1026 bool last_pause_included_initial_mark = false;
1027 bool update_stats = !_g1->evacuation_failed();
1028
1029 #ifndef PRODUCT
1030 if (G1YoungSurvRateVerbose) {
1031 gclog_or_tty->cr();
1032 _short_lived_surv_rate_group->print();
1033 // do that for any other surv rate groups too
1034 }
1035 #endif // PRODUCT
1036
1037 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
1038
1039 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1040 if (last_pause_included_initial_mark) {
1041 record_concurrent_mark_init_end(0.0);
1042 } else {
1043 maybe_start_marking();
1044 }
1045
1046 double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1047 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1048 // This usually happens due to the timer not having the required
1049 // granularity. Some Linuxes are the usual culprits.
1050 // We'll just set it to something (arbitrarily) small.
1051 app_time_ms = 1.0;
1052 }
1053
1054 if (update_stats) {
1055 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1056 // We maintain the invariant that all objects allocated by mutator
1057 // threads will be allocated out of eden regions. So, we can use
1058 // the eden region number allocated since the previous GC to
1059 // calculate the application's allocate rate. The only exception
1060 // to that is humongous objects that are allocated separately. But
1061 // given that humongous object allocations do not really affect
1062 // either the pause's duration nor when the next pause will take
1063 // place we can safely ignore them here.
1064 uint regions_allocated = eden_cset_region_length();
1065 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1066 _alloc_rate_ms_seq->add(alloc_rate_ms);
1067
1068 double interval_ms =
1069 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1070 update_recent_gc_times(end_time_sec, pause_time_ms);
1071 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1072 if (recent_avg_pause_time_ratio() < 0.0 ||
1073 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1074 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1075 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1076 if (_recent_avg_pause_time_ratio < 0.0) {
1077 _recent_avg_pause_time_ratio = 0.0;
1078 } else {
1079 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1080 _recent_avg_pause_time_ratio = 1.0;
1081 }
1082 }
1083 }
1084
1085 bool new_in_marking_window = collector_state()->in_marking_window();
1086 bool new_in_marking_window_im = false;
1087 if (last_pause_included_initial_mark) {
1088 new_in_marking_window = true;
1089 new_in_marking_window_im = true;
1090 }
1091
1092 if (collector_state()->last_young_gc()) {
1093 // This is supposed to to be the "last young GC" before we start
1094 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1095 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1096
1097 if (next_gc_should_be_mixed("start mixed GCs",
1098 "do not start mixed GCs")) {
1099 collector_state()->set_gcs_are_young(false);
1100 } else {
1101 // We aborted the mixed GC phase early.
1102 abort_time_to_mixed_tracking();
1103 }
1104
1105 collector_state()->set_last_young_gc(false);
1106 }
1107
1108 if (!collector_state()->last_gc_was_young()) {
1109 // This is a mixed GC. Here we decide whether to continue doing
1110 // mixed GCs or not.
1111 if (!next_gc_should_be_mixed("continue mixed GCs",
1112 "do not continue mixed GCs")) {
1113 collector_state()->set_gcs_are_young(true);
1114
1115 maybe_start_marking();
1116 }
1117 }
1118
1119 _short_lived_surv_rate_group->start_adding_regions();
1120 // Do that for any other surv rate groups
1121
1122 if (update_stats) {
1123 double cost_per_card_ms = 0.0;
1124 double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1125 if (_pending_cards > 0) {
1126 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1127 _cost_per_card_ms_seq->add(cost_per_card_ms);
1128 }
1129 _cost_scan_hcc_seq->add(cost_scan_hcc);
1130
1131 double cost_per_entry_ms = 0.0;
1132 if (cards_scanned > 10) {
1133 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1134 if (collector_state()->last_gc_was_young()) {
1135 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1136 } else {
1137 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1138 }
1139 }
1140
1141 if (_max_rs_lengths > 0) {
1142 double cards_per_entry_ratio =
1143 (double) cards_scanned / (double) _max_rs_lengths;
1144 if (collector_state()->last_gc_was_young()) {
1145 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1146 } else {
1147 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1148 }
1149 }
1150
1151 // This is defensive. For a while _max_rs_lengths could get
1152 // smaller than _recorded_rs_lengths which was causing
1153 // rs_length_diff to get very large and mess up the RSet length
1154 // predictions. The reason was unsafe concurrent updates to the
1155 // _inc_cset_recorded_rs_lengths field which the code below guards
1156 // against (see CR 7118202). This bug has now been fixed (see CR
1157 // 7119027). However, I'm still worried that
1158 // _inc_cset_recorded_rs_lengths might still end up somewhat
1159 // inaccurate. The concurrent refinement thread calculates an
1160 // RSet's length concurrently with other CR threads updating it
1161 // which might cause it to calculate the length incorrectly (if,
1162 // say, it's in mid-coarsening). So I'll leave in the defensive
1163 // conditional below just in case.
1164 size_t rs_length_diff = 0;
1165 if (_max_rs_lengths > _recorded_rs_lengths) {
1166 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1167 }
1168 _rs_length_diff_seq->add((double) rs_length_diff);
1169
1170 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1171 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1172 double cost_per_byte_ms = 0.0;
1173
1174 if (copied_bytes > 0) {
1175 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1176 if (collector_state()->in_marking_window()) {
1177 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1178 } else {
1179 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1180 }
1181 }
1182
1183 if (young_cset_region_length() > 0) {
1184 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1185 young_cset_region_length());
1186 }
1187
1188 if (old_cset_region_length() > 0) {
1189 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1190 old_cset_region_length());
1191 }
1192
1193 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1194
1195 _pending_cards_seq->add((double) _pending_cards);
1196 _rs_lengths_seq->add((double) _max_rs_lengths);
1197 }
1198
1199 collector_state()->set_in_marking_window(new_in_marking_window);
1200 collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1201 _free_regions_at_end_of_collection = _g1->num_free_regions();
1202 // IHOP control wants to know the expected young gen length if it were not
1203 // restrained by the heap reserve. Using the actual length would make the
1204 // prediction too small and the limit the young gen every time we get to the
1205 // predicted target occupancy.
1206 size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
1207 update_rs_lengths_prediction();
1208
1209 update_ihop_prediction(app_time_ms / 1000.0,
1210 _bytes_allocated_in_old_since_last_gc,
1211 last_unrestrained_young_length * HeapRegion::GrainBytes);
1212 _bytes_allocated_in_old_since_last_gc = 0;
1213
1214 _ihop_control->send_trace_event(_g1->gc_tracer_stw());
1215
1216 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1217 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1218
1219 double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1220
1221 if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1222 ergo_verbose2(ErgoTiming,
1223 "adjust concurrent refinement thresholds",
1224 ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1225 ergo_format_ms("Update RS time goal")
1226 ergo_format_ms("Scan HCC time"),
1227 update_rs_time_goal_ms,
1228 scan_hcc_time_ms);
1229
1230 update_rs_time_goal_ms = 0;
1231 } else {
1232 update_rs_time_goal_ms -= scan_hcc_time_ms;
1233 }
1234 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1235 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1236 update_rs_time_goal_ms);
1237
1238 cset_chooser()->verify();
1239 }
1240
1241 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1242 if (G1UseAdaptiveIHOP) {
1243 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1244 G1CollectedHeap::heap()->max_capacity(),
1245 &_predictor,
1246 G1ReservePercent,
1247 G1HeapWastePercent);
1248 } else {
1249 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1250 G1CollectedHeap::heap()->max_capacity());
1251 }
1252 }
1253
1254 void G1CollectorPolicy::update_ihop_prediction(double mutator_time_s,
1255 size_t mutator_alloc_bytes,
1256 size_t young_gen_size) {
1257 // Always try to update IHOP prediction. Even evacuation failures give information
1258 // about e.g. whether to start IHOP earlier next time.
1259
1260 // Avoid using really small application times that might create samples with
1261 // very high or very low values. They may be caused by e.g. back-to-back gcs.
1262 double const min_valid_time = 1e-6;
1263
1264 bool report = false;
1265
1266 double marking_to_mixed_time = -1.0;
1267 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1268 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1269 assert(marking_to_mixed_time > 0.0,
1270 "Initial mark to mixed time must be larger than zero but is %.3f",
1271 marking_to_mixed_time);
1272 if (marking_to_mixed_time > min_valid_time) {
1273 _ihop_control->update_marking_length(marking_to_mixed_time);
1274 report = true;
1275 }
1276 }
1277
1278 // As an approximation for the young gc promotion rates during marking we use
1279 // all of them. In many applications there are only a few if any young gcs during
1280 // marking, which makes any prediction useless. This increases the accuracy of the
1281 // prediction.
1282 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1283 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1284 report = true;
1285 }
1286
1287 if (report) {
1288 report_ihop_statistics();
1289 }
1290 }
1291
1292 void G1CollectorPolicy::report_ihop_statistics() {
1293 _ihop_control->print();
1294 }
1295
1296 #define EXT_SIZE_FORMAT "%.1f%s"
1297 #define EXT_SIZE_PARAMS(bytes) \
1298 byte_size_in_proper_unit((double)(bytes)), \
1299 proper_unit_for_byte_size((bytes))
1300
1301 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1302 YoungList* young_list = _g1->young_list();
1303 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1304 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1305 _heap_capacity_bytes_before_gc = _g1->capacity();
1306 _heap_used_bytes_before_gc = _g1->used();
1307
1308 _eden_capacity_bytes_before_gc =
1309 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1310
1311 if (full) {
1312 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1313 }
1314 }
1315
1316 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1317 size_t bytes_after = _g1->used();
1318 size_t capacity = _g1->capacity();
1319
1320 gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1321 byte_size_in_proper_unit(bytes_before),
1322 proper_unit_for_byte_size(bytes_before),
1323 byte_size_in_proper_unit(bytes_after),
1324 proper_unit_for_byte_size(bytes_after),
1325 byte_size_in_proper_unit(capacity),
1326 proper_unit_for_byte_size(capacity));
1327 }
1328
1329 void G1CollectorPolicy::print_heap_transition() const {
1330 print_heap_transition(_heap_used_bytes_before_gc);
1331 }
1332
1333 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1334 YoungList* young_list = _g1->young_list();
1335
1336 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1337 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1338 size_t heap_used_bytes_after_gc = _g1->used();
1339
1340 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1341 size_t eden_capacity_bytes_after_gc =
1342 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1343
1344 gclog_or_tty->print(
1345 " [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1346 "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1347 "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1348 EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1349 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1350 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1351 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1352 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1353 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1354 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1355 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1356 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1357 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1358 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1359
1360 if (full) {
1361 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1362 }
1363
1364 gclog_or_tty->cr();
1365 }
1366
1367 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1368 phase_times()->print(pause_time_sec);
1369 }
1370
1371 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1372 double update_rs_processed_buffers,
1373 double goal_ms) {
1374 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1375 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1376
1377 if (G1UseAdaptiveConcRefinement) {
1378 const int k_gy = 3, k_gr = 6;
1379 const double inc_k = 1.1, dec_k = 0.9;
1380
1381 int g = cg1r->green_zone();
1382 if (update_rs_time > goal_ms) {
1383 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1384 } else {
1385 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1386 g = (int)MAX2(g * inc_k, g + 1.0);
1387 }
1388 }
1389 // Change the refinement threads params
1390 cg1r->set_green_zone(g);
1391 cg1r->set_yellow_zone(g * k_gy);
1392 cg1r->set_red_zone(g * k_gr);
1393 cg1r->reinitialize_threads();
1394
1395 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1396 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1397 cg1r->yellow_zone());
1398 // Change the barrier params
1399 dcqs.set_process_completed_threshold(processing_threshold);
1400 dcqs.set_max_completed_queue(cg1r->red_zone());
1401 }
1402
1403 int curr_queue_size = dcqs.completed_buffers_num();
1404 if (curr_queue_size >= cg1r->yellow_zone()) {
1405 dcqs.set_completed_queue_padding(curr_queue_size);
1406 } else {
1407 dcqs.set_completed_queue_padding(0);
1408 }
1409 dcqs.notify_if_necessary();
1410 }
1411
1412 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1413 return (size_t) get_new_prediction(_rs_length_diff_seq);
1414 }
1415
1416 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1417 return get_new_prediction(_alloc_rate_ms_seq);
1418 }
1419
1420 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1421 return get_new_prediction(_cost_per_card_ms_seq);
1422 }
1423
1424 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1425 return get_new_prediction(_cost_scan_hcc_seq);
1426 }
1427
1428 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1429 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1430 }
1431
1432 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1433 return get_new_prediction(_young_cards_per_entry_ratio_seq);
1434 }
1435
1436 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1437 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1438 return predict_young_cards_per_entry_ratio();
1439 } else {
1440 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1441 }
1442 }
1443
1444 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1445 return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1446 }
1447
1448 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1449 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1450 }
1451
1452 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1453 if (collector_state()->gcs_are_young()) {
1454 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1455 } else {
1456 return predict_mixed_rs_scan_time_ms(card_num);
1457 }
1458 }
1459
1460 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1461 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1462 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1463 } else {
1464 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1465 }
1466 }
1467
1468 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1469 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1470 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1471 } else {
1472 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1473 }
1474 }
1475
1476 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1477 if (collector_state()->during_concurrent_mark()) {
1478 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1479 } else {
1480 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1481 }
1482 }
1483
1484 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1485 return get_new_prediction(_constant_other_time_ms_seq);
1486 }
1487
1488 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1489 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1490 }
1491
1492 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1493 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1494 }
1495
1496 double G1CollectorPolicy::predict_remark_time_ms() const {
1497 return get_new_prediction(_concurrent_mark_remark_times_ms);
1498 }
1499
1500 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1501 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1502 }
1503
1504 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1505 TruncatedSeq* seq = surv_rate_group->get_seq(age);
1506 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1507 double pred = get_new_prediction(seq);
1508 if (pred > 1.0) {
1509 pred = 1.0;
1510 }
1511 return pred;
1512 }
1513
1514 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1515 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1516 }
1517
1518 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1519 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1520 }
1521
1522 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1523 size_t scanned_cards) const {
1524 return
1525 predict_rs_update_time_ms(pending_cards) +
1526 predict_rs_scan_time_ms(scanned_cards) +
1527 predict_constant_other_time_ms();
1528 }
1529
1530 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1531 size_t rs_length = predict_rs_length_diff();
1532 size_t card_num;
1533 if (collector_state()->gcs_are_young()) {
1534 card_num = predict_young_card_num(rs_length);
1535 } else {
1536 card_num = predict_non_young_card_num(rs_length);
1537 }
1538 return predict_base_elapsed_time_ms(pending_cards, card_num);
1539 }
1540
1541 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1542 size_t bytes_to_copy;
1543 if (hr->is_marked())
1544 bytes_to_copy = hr->max_live_bytes();
1545 else {
1546 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1547 int age = hr->age_in_surv_rate_group();
1548 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1549 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1550 }
1551 return bytes_to_copy;
1552 }
1553
1554 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1555 bool for_young_gc) const {
1556 size_t rs_length = hr->rem_set()->occupied();
1557 size_t card_num;
1558
1559 // Predicting the number of cards is based on which type of GC
1560 // we're predicting for.
1561 if (for_young_gc) {
1562 card_num = predict_young_card_num(rs_length);
1563 } else {
1564 card_num = predict_non_young_card_num(rs_length);
1565 }
1566 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1567
1568 double region_elapsed_time_ms =
1569 predict_rs_scan_time_ms(card_num) +
1570 predict_object_copy_time_ms(bytes_to_copy);
1571
1572 // The prediction of the "other" time for this region is based
1573 // upon the region type and NOT the GC type.
1574 if (hr->is_young()) {
1575 region_elapsed_time_ms += predict_young_other_time_ms(1);
1576 } else {
1577 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1578 }
1579 return region_elapsed_time_ms;
1580 }
1581
1582 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1583 uint survivor_cset_region_length) {
1584 _eden_cset_region_length = eden_cset_region_length;
1585 _survivor_cset_region_length = survivor_cset_region_length;
1586 _old_cset_region_length = 0;
1587 }
1588
1589 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1590 _recorded_rs_lengths = rs_lengths;
1591 }
1592
1593 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1594 double elapsed_ms) {
1595 _recent_gc_times_ms->add(elapsed_ms);
1596 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1597 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1598 }
1599
1600 size_t G1CollectorPolicy::expansion_amount() const {
1601 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1602 double threshold = _gc_overhead_perc;
1603 if (recent_gc_overhead > threshold) {
1604 // We will double the existing space, or take
1605 // G1ExpandByPercentOfAvailable % of the available expansion
1606 // space, whichever is smaller, bounded below by a minimum
1607 // expansion (unless that's all that's left.)
1608 const size_t min_expand_bytes = 1*M;
1609 size_t reserved_bytes = _g1->max_capacity();
1610 size_t committed_bytes = _g1->capacity();
1611 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1612 size_t expand_bytes;
1613 size_t expand_bytes_via_pct =
1614 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1615 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1616 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1617 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1618
1619 ergo_verbose5(ErgoHeapSizing,
1620 "attempt heap expansion",
1621 ergo_format_reason("recent GC overhead higher than "
1622 "threshold after GC")
1623 ergo_format_perc("recent GC overhead")
1624 ergo_format_perc("threshold")
1625 ergo_format_byte("uncommitted")
1626 ergo_format_byte_perc("calculated expansion amount"),
1627 recent_gc_overhead, threshold,
1628 uncommitted_bytes,
1629 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1630
1631 return expand_bytes;
1632 } else {
1633 return 0;
1634 }
1635 }
1636
1637 void G1CollectorPolicy::print_tracing_info() const {
1638 _trace_young_gen_time_data.print();
1639 _trace_old_gen_time_data.print();
1640 }
1641
1642 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1643 #ifndef PRODUCT
1644 _short_lived_surv_rate_group->print_surv_rate_summary();
1645 // add this call for any other surv rate groups
1646 #endif // PRODUCT
1647 }
1648
1649 bool G1CollectorPolicy::is_young_list_full() const {
1650 uint young_list_length = _g1->young_list()->length();
1651 uint young_list_target_length = _young_list_target_length;
1652 return young_list_length >= young_list_target_length;
1653 }
1654
1655 bool G1CollectorPolicy::can_expand_young_list() const {
1656 uint young_list_length = _g1->young_list()->length();
1657 uint young_list_max_length = _young_list_max_length;
1658 return young_list_length < young_list_max_length;
1659 }
1660
1661 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1662 uint expansion_region_num = 0;
1663 if (GCLockerEdenExpansionPercent > 0) {
1664 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1665 double expansion_region_num_d = perc * (double) _young_list_target_length;
1666 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1667 // less than 1.0) we'll get 1.
1668 expansion_region_num = (uint) ceil(expansion_region_num_d);
1669 } else {
1670 assert(expansion_region_num == 0, "sanity");
1671 }
1672 _young_list_max_length = _young_list_target_length + expansion_region_num;
1673 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1674 }
1675
1676 // Calculates survivor space parameters.
1677 void G1CollectorPolicy::update_survivors_policy() {
1678 double max_survivor_regions_d =
1679 (double) _young_list_target_length / (double) SurvivorRatio;
1680 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1681 // smaller than 1.0) we'll get 1.
1682 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1683
1684 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1685 HeapRegion::GrainWords * _max_survivor_regions, counters());
1686 }
1687
1688 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1689 // We actually check whether we are marking here and not if we are in a
1690 // reclamation phase. This means that we will schedule a concurrent mark
1691 // even while we are still in the process of reclaiming memory.
1692 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1693 if (!during_cycle) {
1694 ergo_verbose1(ErgoConcCycles,
1695 "request concurrent cycle initiation",
1696 ergo_format_reason("requested by GC cause")
1697 ergo_format_str("GC cause"),
1698 GCCause::to_string(gc_cause));
1699 collector_state()->set_initiate_conc_mark_if_possible(true);
1700 return true;
1701 } else {
1702 ergo_verbose1(ErgoConcCycles,
1703 "do not request concurrent cycle initiation",
1704 ergo_format_reason("concurrent cycle already in progress")
1705 ergo_format_str("GC cause"),
1706 GCCause::to_string(gc_cause));
1707 return false;
1708 }
1709 }
1710
1711 void G1CollectorPolicy::initiate_conc_mark() {
1712 collector_state()->set_during_initial_mark_pause(true);
1713 collector_state()->set_initiate_conc_mark_if_possible(false);
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 if there is no marking or reclamation going on.
1733 initiate_conc_mark();
1734 ergo_verbose0(ErgoConcCycles,
1735 "initiate concurrent cycle",
1736 ergo_format_reason("concurrent cycle initiation requested"));
1737 } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
1738 // Initiate a user requested initial mark. An initial mark must be young only
1739 // GC, so the collector state must be updated to reflect this.
1740 collector_state()->set_gcs_are_young(true);
1741 collector_state()->set_last_young_gc(false);
1742
1743 abort_time_to_mixed_tracking();
1744 initiate_conc_mark();
1745 ergo_verbose0(ErgoConcCycles,
1746 "initiate concurrent cycle",
1747 ergo_format_reason("user requested concurrent cycle"));
1748 } else {
1749 // The concurrent marking thread is still finishing up the
1750 // previous cycle. If we start one right now the two cycles
1751 // overlap. In particular, the concurrent marking thread might
1752 // be in the process of clearing the next marking bitmap (which
1753 // we will use for the next cycle if we start one). Starting a
1754 // cycle now will be bad given that parts of the marking
1755 // information might get cleared by the marking thread. And we
1756 // cannot wait for the marking thread to finish the cycle as it
1757 // periodically yields while clearing the next marking bitmap
1758 // and, if it's in a yield point, it's waiting for us to
1759 // finish. So, at this point we will not start a cycle and we'll
1760 // let the concurrent marking thread complete the last one.
1761 ergo_verbose0(ErgoConcCycles,
1762 "do not initiate concurrent cycle",
1763 ergo_format_reason("concurrent cycle already in progress"));
1764 }
1765 }
1766 }
1767
1768 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1769 G1CollectedHeap* _g1h;
1770 CSetChooserParUpdater _cset_updater;
1771
1772 public:
1773 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1774 uint chunk_size) :
1775 _g1h(G1CollectedHeap::heap()),
1776 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1777
1778 bool doHeapRegion(HeapRegion* r) {
1779 // Do we have any marking information for this region?
1780 if (r->is_marked()) {
1781 // We will skip any region that's currently used as an old GC
1782 // alloc region (we should not consider those for collection
1783 // before we fill them up).
1784 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1785 _cset_updater.add_region(r);
1786 }
1787 }
1788 return false;
1789 }
1790 };
1791
1792 class ParKnownGarbageTask: public AbstractGangTask {
1793 CollectionSetChooser* _hrSorted;
1794 uint _chunk_size;
1795 G1CollectedHeap* _g1;
1796 HeapRegionClaimer _hrclaimer;
1797
1798 public:
1799 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1800 AbstractGangTask("ParKnownGarbageTask"),
1801 _hrSorted(hrSorted), _chunk_size(chunk_size),
1802 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1803
1804 void work(uint worker_id) {
1805 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1806 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1807 }
1808 };
1809
1810 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1811 assert(n_workers > 0, "Active gc workers should be greater than 0");
1812 const uint overpartition_factor = 4;
1813 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1814 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1815 }
1816
1817 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1818 cset_chooser()->clear();
1819
1820 WorkGang* workers = _g1->workers();
1821 uint n_workers = workers->active_workers();
1822
1823 uint n_regions = _g1->num_regions();
1824 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1825 cset_chooser()->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1826 ParKnownGarbageTask par_known_garbage_task(cset_chooser(), chunk_size, n_workers);
1827 workers->run_task(&par_known_garbage_task);
1828
1829 cset_chooser()->sort_regions();
1830
1831 double end_sec = os::elapsedTime();
1832 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1833 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1834 _prev_collection_pause_end_ms += elapsed_time_ms;
1835
1836 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1837 }
1838
1839 // Add the heap region at the head of the non-incremental collection set
1840 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1841 assert(_inc_cset_build_state == Active, "Precondition");
1842 assert(hr->is_old(), "the region should be old");
1843
1844 assert(!hr->in_collection_set(), "should not already be in the CSet");
1845 _g1->register_old_region_with_cset(hr);
1846 hr->set_next_in_collection_set(_collection_set);
1847 _collection_set = hr;
1848 _collection_set_bytes_used_before += hr->used();
1849 size_t rs_length = hr->rem_set()->occupied();
1850 _recorded_rs_lengths += rs_length;
1851 _old_cset_region_length += 1;
1852 }
1853
1854 // Initialize the per-collection-set information
1855 void G1CollectorPolicy::start_incremental_cset_building() {
1856 assert(_inc_cset_build_state == Inactive, "Precondition");
1857
1858 _inc_cset_head = NULL;
1859 _inc_cset_tail = NULL;
1860 _inc_cset_bytes_used_before = 0;
1861
1862 _inc_cset_max_finger = 0;
1863 _inc_cset_recorded_rs_lengths = 0;
1864 _inc_cset_recorded_rs_lengths_diffs = 0;
1865 _inc_cset_predicted_elapsed_time_ms = 0.0;
1866 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1867 _inc_cset_build_state = Active;
1868 }
1869
1870 void G1CollectorPolicy::finalize_incremental_cset_building() {
1871 assert(_inc_cset_build_state == Active, "Precondition");
1872 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1873
1874 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1875 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1876 // that adds a new region to the CSet. Further updates by the
1877 // concurrent refinement thread that samples the young RSet lengths
1878 // are accumulated in the *_diffs fields. Here we add the diffs to
1879 // the "main" fields.
1880
1881 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1882 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1883 } else {
1884 // This is defensive. The diff should in theory be always positive
1885 // as RSets can only grow between GCs. However, given that we
1886 // sample their size concurrently with other threads updating them
1887 // it's possible that we might get the wrong size back, which
1888 // could make the calculations somewhat inaccurate.
1889 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1890 if (_inc_cset_recorded_rs_lengths >= diffs) {
1891 _inc_cset_recorded_rs_lengths -= diffs;
1892 } else {
1893 _inc_cset_recorded_rs_lengths = 0;
1894 }
1895 }
1896 _inc_cset_predicted_elapsed_time_ms +=
1897 _inc_cset_predicted_elapsed_time_ms_diffs;
1898
1899 _inc_cset_recorded_rs_lengths_diffs = 0;
1900 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1901 }
1902
1903 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1904 // This routine is used when:
1905 // * adding survivor regions to the incremental cset at the end of an
1906 // evacuation pause,
1907 // * adding the current allocation region to the incremental cset
1908 // when it is retired, and
1909 // * updating existing policy information for a region in the
1910 // incremental cset via young list RSet sampling.
1911 // Therefore this routine may be called at a safepoint by the
1912 // VM thread, or in-between safepoints by mutator threads (when
1913 // retiring the current allocation region) or a concurrent
1914 // refine thread (RSet sampling).
1915
1916 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1917 size_t used_bytes = hr->used();
1918 _inc_cset_recorded_rs_lengths += rs_length;
1919 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1920 _inc_cset_bytes_used_before += used_bytes;
1921
1922 // Cache the values we have added to the aggregated information
1923 // in the heap region in case we have to remove this region from
1924 // the incremental collection set, or it is updated by the
1925 // rset sampling code
1926 hr->set_recorded_rs_length(rs_length);
1927 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1928 }
1929
1930 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1931 size_t new_rs_length) {
1932 // Update the CSet information that is dependent on the new RS length
1933 assert(hr->is_young(), "Precondition");
1934 assert(!SafepointSynchronize::is_at_safepoint(),
1935 "should not be at a safepoint");
1936
1937 // We could have updated _inc_cset_recorded_rs_lengths and
1938 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1939 // that atomically, as this code is executed by a concurrent
1940 // refinement thread, potentially concurrently with a mutator thread
1941 // allocating a new region and also updating the same fields. To
1942 // avoid the atomic operations we accumulate these updates on two
1943 // separate fields (*_diffs) and we'll just add them to the "main"
1944 // fields at the start of a GC.
1945
1946 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1947 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1948 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1949
1950 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1951 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1952 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1953 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1954
1955 hr->set_recorded_rs_length(new_rs_length);
1956 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1957 }
1958
1959 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1960 assert(hr->is_young(), "invariant");
1961 assert(hr->young_index_in_cset() > -1, "should have already been set");
1962 assert(_inc_cset_build_state == Active, "Precondition");
1963
1964 // We need to clear and set the cached recorded/cached collection set
1965 // information in the heap region here (before the region gets added
1966 // to the collection set). An individual heap region's cached values
1967 // are calculated, aggregated with the policy collection set info,
1968 // and cached in the heap region here (initially) and (subsequently)
1969 // by the Young List sampling code.
1970
1971 size_t rs_length = hr->rem_set()->occupied();
1972 add_to_incremental_cset_info(hr, rs_length);
1973
1974 HeapWord* hr_end = hr->end();
1975 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1976
1977 assert(!hr->in_collection_set(), "invariant");
1978 _g1->register_young_region_with_cset(hr);
1979 assert(hr->next_in_collection_set() == NULL, "invariant");
1980 }
1981
1982 // Add the region at the RHS of the incremental cset
1983 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1984 // We should only ever be appending survivors at the end of a pause
1985 assert(hr->is_survivor(), "Logic");
1986
1987 // Do the 'common' stuff
1988 add_region_to_incremental_cset_common(hr);
1989
1990 // Now add the region at the right hand side
1991 if (_inc_cset_tail == NULL) {
1992 assert(_inc_cset_head == NULL, "invariant");
1993 _inc_cset_head = hr;
1994 } else {
1995 _inc_cset_tail->set_next_in_collection_set(hr);
1996 }
1997 _inc_cset_tail = hr;
1998 }
1999
2000 // Add the region to the LHS of the incremental cset
2001 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2002 // Survivors should be added to the RHS at the end of a pause
2003 assert(hr->is_eden(), "Logic");
2004
2005 // Do the 'common' stuff
2006 add_region_to_incremental_cset_common(hr);
2007
2008 // Add the region at the left hand side
2009 hr->set_next_in_collection_set(_inc_cset_head);
2010 if (_inc_cset_head == NULL) {
2011 assert(_inc_cset_tail == NULL, "Invariant");
2012 _inc_cset_tail = hr;
2013 }
2014 _inc_cset_head = hr;
2015 }
2016
2017 #ifndef PRODUCT
2018 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2019 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2020
2021 st->print_cr("\nCollection_set:");
2022 HeapRegion* csr = list_head;
2023 while (csr != NULL) {
2024 HeapRegion* next = csr->next_in_collection_set();
2025 assert(csr->in_collection_set(), "bad CS");
2026 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2027 HR_FORMAT_PARAMS(csr),
2028 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2029 csr->age_in_surv_rate_group_cond());
2030 csr = next;
2031 }
2032 }
2033 #endif // !PRODUCT
2034
2035 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2036 // Returns the given amount of reclaimable bytes (that represents
2037 // the amount of reclaimable space still to be collected) as a
2038 // percentage of the current heap capacity.
2039 size_t capacity_bytes = _g1->capacity();
2040 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2041 }
2042
2043 void G1CollectorPolicy::maybe_start_marking() {
2044 if (need_to_start_conc_mark("end of GC")) {
2045 // Note: this might have already been set, if during the last
2046 // pause we decided to start a cycle but at the beginning of
2047 // this pause we decided to postpone it. That's OK.
2048 collector_state()->set_initiate_conc_mark_if_possible(true);
2049 }
2050 }
2051
2052 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2053 assert(!collector_state()->full_collection(), "must be");
2054 if (collector_state()->during_initial_mark_pause()) {
2055 assert(collector_state()->last_gc_was_young(), "must be");
2056 assert(!collector_state()->last_young_gc(), "must be");
2057 return InitialMarkGC;
2058 } else if (collector_state()->last_young_gc()) {
2059 assert(!collector_state()->during_initial_mark_pause(), "must be");
2060 assert(collector_state()->last_gc_was_young(), "must be");
2061 return LastYoungGC;
2062 } else if (!collector_state()->last_gc_was_young()) {
2063 assert(!collector_state()->during_initial_mark_pause(), "must be");
2064 assert(!collector_state()->last_young_gc(), "must be");
2065 return MixedGC;
2066 } else {
2067 assert(collector_state()->last_gc_was_young(), "must be");
2068 assert(!collector_state()->during_initial_mark_pause(), "must be");
2069 assert(!collector_state()->last_young_gc(), "must be");
2070 return YoungOnlyGC;
2071 }
2072 }
2073
2074 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2075 // Manage the MMU tracker. For some reason it ignores Full GCs.
2076 if (kind != FullGC) {
2077 _mmu_tracker->add_pause(start, end);
2078 }
2079 // Manage the mutator time tracking from initial mark to first mixed gc.
2080 switch (kind) {
2081 case FullGC:
2082 abort_time_to_mixed_tracking();
2083 break;
2084 case Cleanup:
2085 case Remark:
2086 case YoungOnlyGC:
2087 case LastYoungGC:
2088 _initial_mark_to_mixed.add_pause(end - start);
2089 break;
2090 case InitialMarkGC:
2091 _initial_mark_to_mixed.record_initial_mark_end(end);
2092 break;
2093 case MixedGC:
2094 _initial_mark_to_mixed.record_mixed_gc_start(start);
2095 break;
2096 default:
2097 ShouldNotReachHere();
2098 }
2099 }
2100
2101 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2102 _initial_mark_to_mixed.reset();
2103 }
2104
2105 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2106 const char* false_action_str) const {
2107 if (cset_chooser()->is_empty()) {
2108 ergo_verbose0(ErgoMixedGCs,
2109 false_action_str,
2110 ergo_format_reason("candidate old regions not available"));
2111 return false;
2112 }
2113
2114 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2115 size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2116 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2117 double threshold = (double) G1HeapWastePercent;
2118 if (reclaimable_perc <= threshold) {
2119 ergo_verbose4(ErgoMixedGCs,
2120 false_action_str,
2121 ergo_format_reason("reclaimable percentage not over threshold")
2122 ergo_format_region("candidate old regions")
2123 ergo_format_byte_perc("reclaimable")
2124 ergo_format_perc("threshold"),
2125 cset_chooser()->remaining_regions(),
2126 reclaimable_bytes,
2127 reclaimable_perc, threshold);
2128 return false;
2129 }
2130
2131 ergo_verbose4(ErgoMixedGCs,
2132 true_action_str,
2133 ergo_format_reason("candidate old regions available")
2134 ergo_format_region("candidate old regions")
2135 ergo_format_byte_perc("reclaimable")
2136 ergo_format_perc("threshold"),
2137 cset_chooser()->remaining_regions(),
2138 reclaimable_bytes,
2139 reclaimable_perc, threshold);
2140 return true;
2141 }
2142
2143 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2144 // The min old CSet region bound is based on the maximum desired
2145 // number of mixed GCs after a cycle. I.e., even if some old regions
2146 // look expensive, we should add them to the CSet anyway to make
2147 // sure we go through the available old regions in no more than the
2148 // maximum desired number of mixed GCs.
2149 //
2150 // The calculation is based on the number of marked regions we added
2151 // to the CSet chooser in the first place, not how many remain, so
2152 // that the result is the same during all mixed GCs that follow a cycle.
2153
2154 const size_t region_num = (size_t) cset_chooser()->length();
2155 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2156 size_t result = region_num / gc_num;
2157 // emulate ceiling
2158 if (result * gc_num < region_num) {
2159 result += 1;
2160 }
2161 return (uint) result;
2162 }
2163
2164 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2165 // The max old CSet region bound is based on the threshold expressed
2166 // as a percentage of the heap size. I.e., it should bound the
2167 // number of old regions added to the CSet irrespective of how many
2168 // of them are available.
2169
2170 const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2171 const size_t region_num = g1h->num_regions();
2172 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2173 size_t result = region_num * perc / 100;
2174 // emulate ceiling
2175 if (100 * result < region_num * perc) {
2176 result += 1;
2177 }
2178 return (uint) result;
2179 }
2180
2181
2182 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2183 double young_start_time_sec = os::elapsedTime();
2184
2185 YoungList* young_list = _g1->young_list();
2186 finalize_incremental_cset_building();
2187
2188 guarantee(target_pause_time_ms > 0.0,
2189 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2190 guarantee(_collection_set == NULL, "Precondition");
2191
2192 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2193 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2194
2195 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2196 "start choosing CSet",
2197 ergo_format_size("_pending_cards")
2198 ergo_format_ms("predicted base time")
2199 ergo_format_ms("remaining time")
2200 ergo_format_ms("target pause time"),
2201 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2202
2203 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2204
2205 if (collector_state()->last_gc_was_young()) {
2206 _trace_young_gen_time_data.increment_young_collection_count();
2207 } else {
2208 _trace_young_gen_time_data.increment_mixed_collection_count();
2209 }
2210
2211 // The young list is laid with the survivor regions from the previous
2212 // pause are appended to the RHS of the young list, i.e.
2213 // [Newly Young Regions ++ Survivors from last pause].
2214
2215 uint survivor_region_length = young_list->survivor_length();
2216 uint eden_region_length = young_list->eden_length();
2217 init_cset_region_lengths(eden_region_length, survivor_region_length);
2218
2219 HeapRegion* hr = young_list->first_survivor_region();
2220 while (hr != NULL) {
2221 assert(hr->is_survivor(), "badly formed young list");
2222 // There is a convention that all the young regions in the CSet
2223 // are tagged as "eden", so we do this for the survivors here. We
2224 // use the special set_eden_pre_gc() as it doesn't check that the
2225 // region is free (which is not the case here).
2226 hr->set_eden_pre_gc();
2227 hr = hr->get_next_young_region();
2228 }
2229
2230 // Clear the fields that point to the survivor list - they are all young now.
2231 young_list->clear_survivors();
2232
2233 _collection_set = _inc_cset_head;
2234 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2235 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2236
2237 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2238 "add young regions to CSet",
2239 ergo_format_region("eden")
2240 ergo_format_region("survivors")
2241 ergo_format_ms("predicted young region time")
2242 ergo_format_ms("target pause time"),
2243 eden_region_length, survivor_region_length,
2244 _inc_cset_predicted_elapsed_time_ms,
2245 target_pause_time_ms);
2246
2247 // The number of recorded young regions is the incremental
2248 // collection set's current size
2249 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2250
2251 double young_end_time_sec = os::elapsedTime();
2252 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2253
2254 return time_remaining_ms;
2255 }
2256
2257 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2258 double non_young_start_time_sec = os::elapsedTime();
2259 double predicted_old_time_ms = 0.0;
2260
2261
2262 if (!collector_state()->gcs_are_young()) {
2263 cset_chooser()->verify();
2264 const uint min_old_cset_length = calc_min_old_cset_length();
2265 const uint max_old_cset_length = calc_max_old_cset_length();
2266
2267 uint expensive_region_num = 0;
2268 bool check_time_remaining = adaptive_young_list_length();
2269
2270 HeapRegion* hr = cset_chooser()->peek();
2271 while (hr != NULL) {
2272 if (old_cset_region_length() >= max_old_cset_length) {
2273 // Added maximum number of old regions to the CSet.
2274 ergo_verbose2(ErgoCSetConstruction,
2275 "finish adding old regions to CSet",
2276 ergo_format_reason("old CSet region num reached max")
2277 ergo_format_region("old")
2278 ergo_format_region("max"),
2279 old_cset_region_length(), max_old_cset_length);
2280 break;
2281 }
2282
2283
2284 // Stop adding regions if the remaining reclaimable space is
2285 // not above G1HeapWastePercent.
2286 size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2287 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2288 double threshold = (double) G1HeapWastePercent;
2289 if (reclaimable_perc <= threshold) {
2290 // We've added enough old regions that the amount of uncollected
2291 // reclaimable space is at or below the waste threshold. Stop
2292 // adding old regions to the CSet.
2293 ergo_verbose5(ErgoCSetConstruction,
2294 "finish adding old regions to CSet",
2295 ergo_format_reason("reclaimable percentage not over threshold")
2296 ergo_format_region("old")
2297 ergo_format_region("max")
2298 ergo_format_byte_perc("reclaimable")
2299 ergo_format_perc("threshold"),
2300 old_cset_region_length(),
2301 max_old_cset_length,
2302 reclaimable_bytes,
2303 reclaimable_perc, threshold);
2304 break;
2305 }
2306
2307 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2308 if (check_time_remaining) {
2309 if (predicted_time_ms > time_remaining_ms) {
2310 // Too expensive for the current CSet.
2311
2312 if (old_cset_region_length() >= min_old_cset_length) {
2313 // We have added the minimum number of old regions to the CSet,
2314 // we are done with this CSet.
2315 ergo_verbose4(ErgoCSetConstruction,
2316 "finish adding old regions to CSet",
2317 ergo_format_reason("predicted time is too high")
2318 ergo_format_ms("predicted time")
2319 ergo_format_ms("remaining time")
2320 ergo_format_region("old")
2321 ergo_format_region("min"),
2322 predicted_time_ms, time_remaining_ms,
2323 old_cset_region_length(), min_old_cset_length);
2324 break;
2325 }
2326
2327 // We'll add it anyway given that we haven't reached the
2328 // minimum number of old regions.
2329 expensive_region_num += 1;
2330 }
2331 } else {
2332 if (old_cset_region_length() >= min_old_cset_length) {
2333 // In the non-auto-tuning case, we'll finish adding regions
2334 // to the CSet if we reach the minimum.
2335 ergo_verbose2(ErgoCSetConstruction,
2336 "finish adding old regions to CSet",
2337 ergo_format_reason("old CSet region num reached min")
2338 ergo_format_region("old")
2339 ergo_format_region("min"),
2340 old_cset_region_length(), min_old_cset_length);
2341 break;
2342 }
2343 }
2344
2345 // We will add this region to the CSet.
2346 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2347 predicted_old_time_ms += predicted_time_ms;
2348 cset_chooser()->pop(); // already have region via peek()
2349 _g1->old_set_remove(hr);
2350 add_old_region_to_cset(hr);
2351
2352 hr = cset_chooser()->peek();
2353 }
2354 if (hr == NULL) {
2355 ergo_verbose0(ErgoCSetConstruction,
2356 "finish adding old regions to CSet",
2357 ergo_format_reason("candidate old regions not available"));
2358 }
2359
2360 if (expensive_region_num > 0) {
2361 // We print the information once here at the end, predicated on
2362 // whether we added any apparently expensive regions or not, to
2363 // avoid generating output per region.
2364 ergo_verbose4(ErgoCSetConstruction,
2365 "added expensive regions to CSet",
2366 ergo_format_reason("old CSet region num not reached min")
2367 ergo_format_region("old")
2368 ergo_format_region("expensive")
2369 ergo_format_region("min")
2370 ergo_format_ms("remaining time"),
2371 old_cset_region_length(),
2372 expensive_region_num,
2373 min_old_cset_length,
2374 time_remaining_ms);
2375 }
2376
2377 cset_chooser()->verify();
2378 }
2379
2380 stop_incremental_cset_building();
2381
2382 ergo_verbose3(ErgoCSetConstruction,
2383 "finish choosing CSet",
2384 ergo_format_region("old")
2385 ergo_format_ms("predicted old region time")
2386 ergo_format_ms("time remaining"),
2387 old_cset_region_length(),
2388 predicted_old_time_ms, time_remaining_ms);
2389
2390 double non_young_end_time_sec = os::elapsedTime();
2391 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2392 }
2393
2394 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2395 if(TraceYoungGenTime) {
2396 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2397 }
2398 }
2399
2400 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2401 if(TraceYoungGenTime) {
2402 _all_yield_times_ms.add(yield_time_ms);
2403 }
2404 }
2405
2406 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2407 if(TraceYoungGenTime) {
2408 _total.add(pause_time_ms);
2409 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2410 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2411 _parallel.add(phase_times->cur_collection_par_time_ms());
2412 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2413 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2414 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2415 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2416 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2417 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2418
2419 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2420 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2421 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2422 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2423 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2424 phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2425
2426 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2427 _parallel_other.add(parallel_other_time);
2428 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2429 }
2430 }
2431
2432 void TraceYoungGenTimeData::increment_young_collection_count() {
2433 if(TraceYoungGenTime) {
2434 ++_young_pause_num;
2435 }
2436 }
2437
2438 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2439 if(TraceYoungGenTime) {
2440 ++_mixed_pause_num;
2441 }
2442 }
2443
2444 void TraceYoungGenTimeData::print_summary(const char* str,
2445 const NumberSeq* seq) const {
2446 double sum = seq->sum();
2447 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2448 str, sum / 1000.0, seq->avg());
2449 }
2450
2451 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2452 const NumberSeq* seq) const {
2453 print_summary(str, seq);
2454 gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2455 "(num", seq->num(), seq->sd(), seq->maximum());
2456 }
2457
2458 void TraceYoungGenTimeData::print() const {
2459 if (!TraceYoungGenTime) {
2460 return;
2461 }
2462
2463 gclog_or_tty->print_cr("ALL PAUSES");
2464 print_summary_sd(" Total", &_total);
2465 gclog_or_tty->cr();
2466 gclog_or_tty->cr();
2467 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2468 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2469 gclog_or_tty->cr();
2470
2471 gclog_or_tty->print_cr("EVACUATION PAUSES");
2472
2473 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2474 gclog_or_tty->print_cr("none");
2475 } else {
2476 print_summary_sd(" Evacuation Pauses", &_total);
2477 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2478 print_summary(" Parallel Time", &_parallel);
2479 print_summary(" Ext Root Scanning", &_ext_root_scan);
2480 print_summary(" SATB Filtering", &_satb_filtering);
2481 print_summary(" Update RS", &_update_rs);
2482 print_summary(" Scan RS", &_scan_rs);
2483 print_summary(" Object Copy", &_obj_copy);
2484 print_summary(" Termination", &_termination);
2485 print_summary(" Parallel Other", &_parallel_other);
2486 print_summary(" Clear CT", &_clear_ct);
2487 print_summary(" Other", &_other);
2488 }
2489 gclog_or_tty->cr();
2490
2491 gclog_or_tty->print_cr("MISC");
2492 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2493 print_summary_sd(" Yields", &_all_yield_times_ms);
2494 }
2495
2496 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2497 if (TraceOldGenTime) {
2498 _all_full_gc_times.add(full_gc_time_ms);
2499 }
2500 }
2501
2502 void TraceOldGenTimeData::print() const {
2503 if (!TraceOldGenTime) {
2504 return;
2505 }
2506
2507 if (_all_full_gc_times.num() > 0) {
2508 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2509 _all_full_gc_times.num(),
2510 _all_full_gc_times.sum() / 1000.0);
2511 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2512 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2513 _all_full_gc_times.sd(),
2514 _all_full_gc_times.maximum());
2515 }
2516 }