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