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 if ((2.0 /* magic */ * _predictor.sigma()) * bytes_to_copy > free_bytes) {
484 // end condition 3: out-of-space (conservatively!)
485 return false;
486 }
487
488 // success!
489 return true;
490 }
491
492 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
493 // re-calculate the necessary reserve
494 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
495 // We use ceiling so that if reserve_regions_d is > 0.0 (but
496 // smaller than 1.0) we'll get 1.
497 _reserve_regions = (uint) ceil(reserve_regions_d);
498
499 _young_gen_sizer->heap_size_changed(new_number_of_regions);
500 }
501
502 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
503 uint base_min_length) const {
504 uint desired_min_length = 0;
505 if (adaptive_young_list_length()) {
506 if (_alloc_rate_ms_seq->num() > 3) {
507 double now_sec = os::elapsedTime();
508 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
509 double alloc_rate_ms = predict_alloc_rate_ms();
510 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
511 } else {
512 // otherwise we don't have enough info to make the prediction
513 }
514 }
515 desired_min_length += base_min_length;
516 // make sure we don't go below any user-defined minimum bound
517 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
518 }
519
520 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
521 // Here, we might want to also take into account any additional
522 // constraints (i.e., user-defined minimum bound). Currently, we
523 // effectively don't set this bound.
524 return _young_gen_sizer->max_desired_young_length();
525 }
526
527 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t* unbounded_target_length) {
528 update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq), unbounded_target_length);
529 }
530
531 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths, size_t* unbounded_target_length) {
532 update_young_list_target_length(rs_lengths, unbounded_target_length);
533 update_max_gc_locker_expansion();
534 }
535
536 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths, size_t* unbounded_target_length) {
537 _young_list_target_length = bounded_young_list_target_length(rs_lengths, unbounded_target_length);
538 }
539
540 void G1CollectorPolicy::update_young_list_target_length() {
541 update_young_list_target_length(get_new_prediction(_rs_lengths_seq));
542 }
543
544 uint G1CollectorPolicy::bounded_young_list_target_length(size_t rs_lengths, size_t* unbounded_target_length) const {
545 // Calculate the absolute and desired min bounds.
546
547 // This is how many young regions we already have (currently: the survivors).
548 uint base_min_length = recorded_survivor_regions();
549 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
550 // This is the absolute minimum young length. Ensure that we
551 // will at least have one eden region available for allocation.
552 uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
553 // If we shrank the young list target it should not shrink below the current size.
554 desired_min_length = MAX2(desired_min_length, absolute_min_length);
555 // Calculate the absolute and desired max bounds.
556
557 uint desired_max_length = calculate_young_list_desired_max_length();
558
559 uint young_list_target_length = 0;
560 if (adaptive_young_list_length()) {
561 if (collector_state()->gcs_are_young()) {
562 young_list_target_length =
563 calculate_young_list_target_length(rs_lengths,
564 base_min_length,
565 desired_min_length,
566 desired_max_length);
567 } else {
568 // Don't calculate anything and let the code below bound it to
569 // the desired_min_length, i.e., do the next GC as soon as
570 // possible to maximize how many old regions we can add to it.
571 }
572 } else {
573 // The user asked for a fixed young gen so we'll fix the young gen
574 // whether the next GC is young or mixed.
575 young_list_target_length = _young_list_fixed_length;
576 }
577
578 if (unbounded_target_length != NULL) {
579 *unbounded_target_length = young_list_target_length;
580 }
581
582 // We will try our best not to "eat" into the reserve.
583 uint absolute_max_length = 0;
584 if (_free_regions_at_end_of_collection > _reserve_regions) {
585 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
586 }
587 if (desired_max_length > absolute_max_length) {
588 desired_max_length = absolute_max_length;
589 }
590
591 // Make sure we don't go over the desired max length, nor under the
592 // desired min length. In case they clash, desired_min_length wins
593 // which is why that test is second.
594 if (young_list_target_length > desired_max_length) {
595 young_list_target_length = desired_max_length;
596 }
597 if (young_list_target_length < desired_min_length) {
598 young_list_target_length = desired_min_length;
599 }
600
601 assert(young_list_target_length > recorded_survivor_regions(),
602 "we should be able to allocate at least one eden region");
603 assert(young_list_target_length >= absolute_min_length, "post-condition");
604
605 return young_list_target_length;
606 }
607
608 uint
609 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
610 uint base_min_length,
611 uint desired_min_length,
612 uint desired_max_length) const {
613 assert(adaptive_young_list_length(), "pre-condition");
614 assert(collector_state()->gcs_are_young(), "only call this for young GCs");
615
616 // In case some edge-condition makes the desired max length too small...
617 if (desired_max_length <= desired_min_length) {
618 return desired_min_length;
619 }
620
621 // We'll adjust min_young_length and max_young_length not to include
622 // the already allocated young regions (i.e., so they reflect the
623 // min and max eden regions we'll allocate). The base_min_length
624 // will be reflected in the predictions by the
625 // survivor_regions_evac_time prediction.
626 assert(desired_min_length > base_min_length, "invariant");
627 uint min_young_length = desired_min_length - base_min_length;
628 assert(desired_max_length > base_min_length, "invariant");
629 uint max_young_length = desired_max_length - base_min_length;
630
631 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
632 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
633 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
634 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
635 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
636 double base_time_ms =
637 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
638 survivor_regions_evac_time;
639 uint available_free_regions = _free_regions_at_end_of_collection;
640 uint base_free_regions = 0;
641 if (available_free_regions > _reserve_regions) {
642 base_free_regions = available_free_regions - _reserve_regions;
643 }
644
645 // Here, we will make sure that the shortest young length that
646 // makes sense fits within the target pause time.
647
648 if (predict_will_fit(min_young_length, base_time_ms,
649 base_free_regions, target_pause_time_ms)) {
650 // The shortest young length will fit into the target pause time;
651 // we'll now check whether the absolute maximum number of young
652 // regions will fit in the target pause time. If not, we'll do
653 // a binary search between min_young_length and max_young_length.
654 if (predict_will_fit(max_young_length, base_time_ms,
655 base_free_regions, target_pause_time_ms)) {
656 // The maximum young length will fit into the target pause time.
657 // We are done so set min young length to the maximum length (as
658 // the result is assumed to be returned in min_young_length).
659 min_young_length = max_young_length;
660 } else {
661 // The maximum possible number of young regions will not fit within
662 // the target pause time so we'll search for the optimal
663 // length. The loop invariants are:
664 //
665 // min_young_length < max_young_length
666 // min_young_length is known to fit into the target pause time
667 // max_young_length is known not to fit into the target pause time
668 //
669 // Going into the loop we know the above hold as we've just
670 // checked them. Every time around the loop we check whether
671 // the middle value between min_young_length and
672 // max_young_length fits into the target pause time. If it
673 // does, it becomes the new min. If it doesn't, it becomes
674 // the new max. This way we maintain the loop invariants.
675
676 assert(min_young_length < max_young_length, "invariant");
677 uint diff = (max_young_length - min_young_length) / 2;
678 while (diff > 0) {
679 uint young_length = min_young_length + diff;
680 if (predict_will_fit(young_length, base_time_ms,
681 base_free_regions, target_pause_time_ms)) {
682 min_young_length = young_length;
683 } else {
684 max_young_length = young_length;
685 }
686 assert(min_young_length < max_young_length, "invariant");
687 diff = (max_young_length - min_young_length) / 2;
688 }
689 // The results is min_young_length which, according to the
690 // loop invariants, should fit within the target pause time.
691
692 // These are the post-conditions of the binary search above:
693 assert(min_young_length < max_young_length,
694 "otherwise we should have discovered that max_young_length "
695 "fits into the pause target and not done the binary search");
696 assert(predict_will_fit(min_young_length, base_time_ms,
697 base_free_regions, target_pause_time_ms),
698 "min_young_length, the result of the binary search, should "
699 "fit into the pause target");
700 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
701 base_free_regions, target_pause_time_ms),
702 "min_young_length, the result of the binary search, should be "
703 "optimal, so no larger length should fit into the pause target");
704 }
705 } else {
706 // Even the minimum length doesn't fit into the pause time
707 // target, return it as the result nevertheless.
708 }
709 return base_min_length + min_young_length;
710 }
711
712 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
713 double survivor_regions_evac_time = 0.0;
714 for (HeapRegion * r = _recorded_survivor_head;
715 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
716 r = r->get_next_young_region()) {
717 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
718 }
719 return survivor_regions_evac_time;
720 }
721
722 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
723 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
724
725 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
726 if (rs_lengths > _rs_lengths_prediction) {
727 // add 10% to avoid having to recalculate often
728 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
729 update_rs_lengths_prediction(rs_lengths_prediction);
730
731 update_young_list_max_and_target_length(rs_lengths_prediction);
732 }
733 }
734
735 void G1CollectorPolicy::update_rs_lengths_prediction() {
736 update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
737 }
738
739 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
740 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
741 _rs_lengths_prediction = prediction;
742 }
743 }
744
745 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
746 bool is_tlab,
747 bool* gc_overhead_limit_was_exceeded) {
748 guarantee(false, "Not using this policy feature yet.");
749 return NULL;
750 }
751
752 // This method controls how a collector handles one or more
753 // of its generations being fully allocated.
754 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
755 bool is_tlab) {
756 guarantee(false, "Not using this policy feature yet.");
757 return NULL;
758 }
759
760
761 #ifndef PRODUCT
762 bool G1CollectorPolicy::verify_young_ages() {
763 HeapRegion* head = _g1->young_list()->first_region();
764 return
765 verify_young_ages(head, _short_lived_surv_rate_group);
766 // also call verify_young_ages on any additional surv rate groups
767 }
768
769 bool
770 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
771 SurvRateGroup *surv_rate_group) {
772 guarantee( surv_rate_group != NULL, "pre-condition" );
773
774 const char* name = surv_rate_group->name();
775 bool ret = true;
776 int prev_age = -1;
777
778 for (HeapRegion* curr = head;
779 curr != NULL;
780 curr = curr->get_next_young_region()) {
781 SurvRateGroup* group = curr->surv_rate_group();
782 if (group == NULL && !curr->is_survivor()) {
783 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
784 ret = false;
785 }
786
787 if (surv_rate_group == group) {
788 int age = curr->age_in_surv_rate_group();
789
790 if (age < 0) {
791 gclog_or_tty->print_cr("## %s: encountered negative age", name);
792 ret = false;
793 }
794
795 if (age <= prev_age) {
796 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
797 "(%d, %d)", name, age, prev_age);
798 ret = false;
799 }
800 prev_age = age;
801 }
802 }
803
804 return ret;
805 }
806 #endif // PRODUCT
807
808 void G1CollectorPolicy::record_full_collection_start() {
809 _full_collection_start_sec = os::elapsedTime();
810 record_heap_size_info_at_start(true /* full */);
811 // Release the future to-space so that it is available for compaction into.
812 collector_state()->set_full_collection(true);
813 }
814
815 void G1CollectorPolicy::record_full_collection_end() {
816 // Consider this like a collection pause for the purposes of allocation
817 // since last pause.
818 double end_sec = os::elapsedTime();
819 double full_gc_time_sec = end_sec - _full_collection_start_sec;
820 double full_gc_time_ms = full_gc_time_sec * 1000.0;
821
822 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
823
824 update_recent_gc_times(end_sec, full_gc_time_ms);
825
826 collector_state()->set_full_collection(false);
827
828 // "Nuke" the heuristics that control the young/mixed GC
829 // transitions and make sure we start with young GCs after the Full GC.
830 collector_state()->set_gcs_are_young(true);
831 collector_state()->set_last_young_gc(false);
832 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
833 collector_state()->set_during_initial_mark_pause(false);
834 collector_state()->set_in_marking_window(false);
835 collector_state()->set_in_marking_window_im(false);
836
837 _short_lived_surv_rate_group->start_adding_regions();
838 // also call this on any additional surv rate groups
839
840 record_survivor_regions(0, NULL, NULL);
841
842 _free_regions_at_end_of_collection = _g1->num_free_regions();
843 // Reset survivors SurvRateGroup.
844 _survivor_surv_rate_group->reset();
845 update_young_list_max_and_target_length();
846 update_rs_lengths_prediction();
847 _collectionSetChooser->clear();
848
849 _last_old_allocated_bytes = 0;
850
851 record_pause(FullGC, _full_collection_start_sec, end_sec);
852 }
853
854 void G1CollectorPolicy::record_stop_world_start() {
855 _stop_world_start = os::elapsedTime();
856 }
857
858 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
859 // We only need to do this here as the policy will only be applied
860 // to the GC we're about to start. so, no point is calculating this
861 // every time we calculate / recalculate the target young length.
862 update_survivors_policy();
863
864 assert(_g1->used() == _g1->recalculate_used(),
865 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
866 _g1->used(), _g1->recalculate_used());
867
868 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
869 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
870 _stop_world_start = 0.0;
871
872 record_heap_size_info_at_start(false /* full */);
873
874 phase_times()->record_cur_collection_start_sec(start_time_sec);
875 _pending_cards = _g1->pending_card_num();
876
877 _collection_set_bytes_used_before = 0;
878 _bytes_copied_during_gc = 0;
879
880 collector_state()->set_last_gc_was_young(false);
881
882 // do that for any other surv rate groups
883 _short_lived_surv_rate_group->stop_adding_regions();
884 _survivors_age_table.clear();
885
886 assert( verify_young_ages(), "region age verification" );
887 }
888
889 void G1CollectorPolicy::record_concurrent_mark_init_end(double
890 mark_init_elapsed_time_ms) {
891 collector_state()->set_during_marking(true);
892 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
893 collector_state()->set_during_initial_mark_pause(false);
894 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
895 }
896
897 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
898 _mark_remark_start_sec = os::elapsedTime();
899 collector_state()->set_during_marking(false);
900 }
901
902 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
903 double end_time_sec = os::elapsedTime();
904 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
905 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
906 _cur_mark_stop_world_time_ms += elapsed_time_ms;
907 _prev_collection_pause_end_ms += elapsed_time_ms;
908
909 record_pause(Remark, _mark_remark_start_sec, end_time_sec);
910 }
911
912 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
913 _mark_cleanup_start_sec = os::elapsedTime();
914 }
915
916 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
917 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
918 "skip last young-only gc");
919 collector_state()->set_last_young_gc(should_continue_with_reclaim);
920 // We abort the marking phase.
921 if (!should_continue_with_reclaim) {
922 abort_time_to_mixed_tracking();
923 }
924 collector_state()->set_in_marking_window(false);
925 }
926
927 void G1CollectorPolicy::record_concurrent_pause() {
928 if (_stop_world_start > 0.0) {
929 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
930 _trace_young_gen_time_data.record_yield_time(yield_ms);
931 }
932 }
933
934 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
935 return phase_times()->average_time_ms(phase);
936 }
937
938 double G1CollectorPolicy::young_other_time_ms() const {
939 return phase_times()->young_cset_choice_time_ms() +
940 phase_times()->young_free_cset_time_ms();
941 }
942
943 double G1CollectorPolicy::non_young_other_time_ms() const {
944 return phase_times()->non_young_cset_choice_time_ms() +
945 phase_times()->non_young_free_cset_time_ms();
946
947 }
948
949 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
950 return pause_time_ms -
951 average_time_ms(G1GCPhaseTimes::UpdateRS) -
952 average_time_ms(G1GCPhaseTimes::ScanRS) -
953 average_time_ms(G1GCPhaseTimes::ObjCopy) -
954 average_time_ms(G1GCPhaseTimes::Termination);
955 }
956
957 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
958 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
959 }
960
961 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
962 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
963 }
964
965 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
966 if (about_to_start_mixed_phase()) {
967 return false;
968 }
969
970 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
971
972 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
973 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
974 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
975
976 if (marking_request_bytes > marking_initiating_used_threshold) {
977 if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
978 ergo_verbose5(ErgoConcCycles,
979 "request concurrent cycle initiation",
980 ergo_format_reason("occupancy higher than threshold")
981 ergo_format_byte("occupancy")
982 ergo_format_byte("allocation request")
983 ergo_format_byte_perc("threshold")
984 ergo_format_str("source"),
985 cur_used_bytes,
986 alloc_byte_size,
987 marking_initiating_used_threshold,
988 (double) marking_initiating_used_threshold / _g1->capacity() * 100,
989 source);
990 return true;
991 } else {
992 ergo_verbose5(ErgoConcCycles,
993 "do not request concurrent cycle initiation",
994 ergo_format_reason("still doing mixed collections")
995 ergo_format_byte("occupancy")
996 ergo_format_byte("allocation request")
997 ergo_format_byte_perc("threshold")
998 ergo_format_str("source"),
999 cur_used_bytes,
1000 alloc_byte_size,
1001 marking_initiating_used_threshold,
1002 (double) InitiatingHeapOccupancyPercent,
1003 source);
1004 }
1005 }
1006
1007 return false;
1008 }
1009
1010 // Anything below that is considered to be zero
1011 #define MIN_TIMER_GRANULARITY 0.0000001
1012
1013 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
1014 double end_time_sec = os::elapsedTime();
1015 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1016 "otherwise, the subtraction below does not make sense");
1017 size_t cur_used_bytes = _g1->used();
1018 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1019 bool last_pause_included_initial_mark = false;
1020 bool update_stats = !_g1->evacuation_failed();
1021
1022 #ifndef PRODUCT
1023 if (G1YoungSurvRateVerbose) {
1024 gclog_or_tty->cr();
1025 _short_lived_surv_rate_group->print();
1026 // do that for any other surv rate groups too
1027 }
1028 #endif // PRODUCT
1029
1030 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
1031
1032 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1033 if (last_pause_included_initial_mark) {
1034 record_concurrent_mark_init_end(0.0);
1035 } else {
1036 maybe_start_marking();
1037 }
1038
1039 double app_time_ms = 1.0;
1040
1041 if (update_stats) {
1042 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1043 // this is where we update the allocation rate of the application
1044 app_time_ms =
1045 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1046 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1047 // This usually happens due to the timer not having the required
1048 // granularity. Some Linuxes are the usual culprits.
1049 // We'll just set it to something (arbitrarily) small.
1050 app_time_ms = 1.0;
1051 }
1052 // We maintain the invariant that all objects allocated by mutator
1053 // threads will be allocated out of eden regions. So, we can use
1054 // the eden region number allocated since the previous GC to
1055 // calculate the application's allocate rate. The only exception
1056 // to that is humongous objects that are allocated separately. But
1057 // given that humongous object allocations do not really affect
1058 // either the pause's duration nor when the next pause will take
1059 // place we can safely ignore them here.
1060 uint regions_allocated = eden_cset_region_length();
1061 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1062 _alloc_rate_ms_seq->add(alloc_rate_ms);
1063
1064 double interval_ms =
1065 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1066 update_recent_gc_times(end_time_sec, pause_time_ms);
1067 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1068 if (recent_avg_pause_time_ratio() < 0.0 ||
1069 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1070 #ifndef PRODUCT
1071 // Dump info to allow post-facto debugging
1072 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1073 gclog_or_tty->print_cr("-------------------------------------------");
1074 gclog_or_tty->print_cr("Recent GC Times (ms):");
1075 _recent_gc_times_ms->dump();
1076 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1077 _recent_prev_end_times_for_all_gcs_sec->dump();
1078 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1079 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1080 // In debug mode, terminate the JVM if the user wants to debug at this point.
1081 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1082 #endif // !PRODUCT
1083 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1084 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1085 if (_recent_avg_pause_time_ratio < 0.0) {
1086 _recent_avg_pause_time_ratio = 0.0;
1087 } else {
1088 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1089 _recent_avg_pause_time_ratio = 1.0;
1090 }
1091 }
1092 }
1093
1094 bool new_in_marking_window = collector_state()->in_marking_window();
1095 bool new_in_marking_window_im = false;
1096 if (last_pause_included_initial_mark) {
1097 new_in_marking_window = true;
1098 new_in_marking_window_im = true;
1099 }
1100
1101 if (collector_state()->last_young_gc()) {
1102 // This is supposed to to be the "last young GC" before we start
1103 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1104 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1105
1106 if (next_gc_should_be_mixed("start mixed GCs",
1107 "do not start mixed GCs")) {
1108 collector_state()->set_gcs_are_young(false);
1109 } else {
1110 // We aborted the mixed GC phase early.
1111 abort_time_to_mixed_tracking();
1112 }
1113
1114 collector_state()->set_last_young_gc(false);
1115 }
1116
1117 if (!collector_state()->last_gc_was_young()) {
1118 // This is a mixed GC. Here we decide whether to continue doing
1119 // mixed GCs or not.
1120 if (!next_gc_should_be_mixed("continue mixed GCs",
1121 "do not continue mixed GCs")) {
1122 collector_state()->set_gcs_are_young(true);
1123
1124 maybe_start_marking();
1125 }
1126 }
1127
1128 _short_lived_surv_rate_group->start_adding_regions();
1129 // Do that for any other surv rate groups
1130
1131 if (update_stats) {
1132 double cost_per_card_ms = 0.0;
1133 double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1134 if (_pending_cards > 0) {
1135 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1136 _cost_per_card_ms_seq->add(cost_per_card_ms);
1137 }
1138 _cost_scan_hcc_seq->add(cost_scan_hcc);
1139
1140 double cost_per_entry_ms = 0.0;
1141 if (cards_scanned > 10) {
1142 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1143 if (collector_state()->last_gc_was_young()) {
1144 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1145 } else {
1146 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1147 }
1148 }
1149
1150 if (_max_rs_lengths > 0) {
1151 double cards_per_entry_ratio =
1152 (double) cards_scanned / (double) _max_rs_lengths;
1153 if (collector_state()->last_gc_was_young()) {
1154 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1155 } else {
1156 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1157 }
1158 }
1159
1160 // This is defensive. For a while _max_rs_lengths could get
1161 // smaller than _recorded_rs_lengths which was causing
1162 // rs_length_diff to get very large and mess up the RSet length
1163 // predictions. The reason was unsafe concurrent updates to the
1164 // _inc_cset_recorded_rs_lengths field which the code below guards
1165 // against (see CR 7118202). This bug has now been fixed (see CR
1166 // 7119027). However, I'm still worried that
1167 // _inc_cset_recorded_rs_lengths might still end up somewhat
1168 // inaccurate. The concurrent refinement thread calculates an
1169 // RSet's length concurrently with other CR threads updating it
1170 // which might cause it to calculate the length incorrectly (if,
1171 // say, it's in mid-coarsening). So I'll leave in the defensive
1172 // conditional below just in case.
1173 size_t rs_length_diff = 0;
1174 if (_max_rs_lengths > _recorded_rs_lengths) {
1175 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1176 }
1177 _rs_length_diff_seq->add((double) rs_length_diff);
1178
1179 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1180 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1181 double cost_per_byte_ms = 0.0;
1182
1183 if (copied_bytes > 0) {
1184 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1185 if (collector_state()->in_marking_window()) {
1186 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1187 } else {
1188 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1189 }
1190 }
1191
1192 if (young_cset_region_length() > 0) {
1193 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1194 young_cset_region_length());
1195 }
1196
1197 if (old_cset_region_length() > 0) {
1198 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1199 old_cset_region_length());
1200 }
1201
1202 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1203
1204 _pending_cards_seq->add((double) _pending_cards);
1205 _rs_lengths_seq->add((double) _max_rs_lengths);
1206 }
1207
1208 collector_state()->set_in_marking_window(new_in_marking_window);
1209 collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1210 _free_regions_at_end_of_collection = _g1->num_free_regions();
1211 // IHOP control wants to know the expected young gen length if it were not
1212 // restrained by the heap reserve. Using the actual length would make the
1213 // prediction too small and the limit the young gen every time we get to the
1214 // predicted target occupancy.
1215 size_t last_unrestrained_young_length = 0;
1216 update_young_list_max_and_target_length(&last_unrestrained_young_length);
1217 update_rs_lengths_prediction();
1218
1219 double marking_to_mixed_time = -1.0;
1220 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1221 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1222 assert(marking_to_mixed_time > 0.0,
1223 "Initial mark to mixed time must be larger than zero but is %.3f",
1224 marking_to_mixed_time);
1225 }
1226 // Only update IHOP information on regular GCs.
1227 if (update_stats) {
1228 update_ihop_statistics(marking_to_mixed_time,
1229 app_time_ms / 1000.0,
1230 _last_old_allocated_bytes,
1231 last_unrestrained_young_length * HeapRegion::GrainBytes);
1232 }
1233 _last_old_allocated_bytes = 0;
1234
1235 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1236 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1237
1238 double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1239
1240 if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1241 ergo_verbose2(ErgoTiming,
1242 "adjust concurrent refinement thresholds",
1243 ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1244 ergo_format_ms("Update RS time goal")
1245 ergo_format_ms("Scan HCC time"),
1246 update_rs_time_goal_ms,
1247 scan_hcc_time_ms);
1248
1249 update_rs_time_goal_ms = 0;
1250 } else {
1251 update_rs_time_goal_ms -= scan_hcc_time_ms;
1252 }
1253 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1254 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1255 update_rs_time_goal_ms);
1256
1257 _collectionSetChooser->verify();
1258 }
1259
1260 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1261 if (G1UseAdaptiveIHOP) {
1262 // The target occupancy is the total heap occupancy we want to hit. First, we
1263 // want to avoid eating into the reserve intended for young GC (to avoid unnecessary
1264 // throughput loss). Additionally G1 is free to not clean out up to
1265 // G1HeapWastePercent of heap, that space also cannot be used for allocation
1266 // while marking.
1267 size_t safe_heap_percentage = (size_t) (G1ReservePercent + G1HeapWastePercent);
1268 size_t target_occupancy = 0;
1269
1270 if (safe_heap_percentage < 100) {
1271 target_occupancy = G1CollectedHeap::heap()->max_capacity() * (100.0 - safe_heap_percentage) / 100.0;
1272 }
1273 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1274 target_occupancy,
1275 &_predictor);
1276 } else {
1277 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1278 G1CollectedHeap::heap()->max_capacity());
1279 }
1280 }
1281
1282 void G1CollectorPolicy::update_ihop_statistics(double marking_time,
1283 double mutator_time_s,
1284 size_t mutator_alloc_bytes,
1285 size_t young_gen_size) {
1286 bool report = false;
1287
1288 // To avoid using really small times that may be caused by e.g. back-to-back gcs
1289 // we filter them out.
1290 double const min_valid_time = 1e-6;
1291
1292 if (marking_time > min_valid_time) {
1293 _ihop_control->update_time_to_mixed(marking_time);
1294 report = true;
1295 }
1296
1297 // As an approximation for the young gc promotion rates during marking we use
1298 // all of them. In many applications there are only a few if any young gcs during
1299 // marking, which makes any prediction useless. This increases the accuracy of the
1300 // prediction.
1301 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1302 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1303 report = true;
1304 }
1305
1306 if (report) {
1307 report_ihop_statistics();
1308 }
1309 }
1310
1311 void G1CollectorPolicy::report_ihop_statistics() {
1312 _ihop_control->print();
1313 }
1314
1315 #define EXT_SIZE_FORMAT "%.1f%s"
1316 #define EXT_SIZE_PARAMS(bytes) \
1317 byte_size_in_proper_unit((double)(bytes)), \
1318 proper_unit_for_byte_size((bytes))
1319
1320 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1321 YoungList* young_list = _g1->young_list();
1322 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1323 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1324 _heap_capacity_bytes_before_gc = _g1->capacity();
1325 _heap_used_bytes_before_gc = _g1->used();
1326 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1327
1328 _eden_capacity_bytes_before_gc =
1329 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1330
1331 if (full) {
1332 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1333 }
1334 }
1335
1336 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1337 size_t bytes_after = _g1->used();
1338 size_t capacity = _g1->capacity();
1339
1340 gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1341 byte_size_in_proper_unit(bytes_before),
1342 proper_unit_for_byte_size(bytes_before),
1343 byte_size_in_proper_unit(bytes_after),
1344 proper_unit_for_byte_size(bytes_after),
1345 byte_size_in_proper_unit(capacity),
1346 proper_unit_for_byte_size(capacity));
1347 }
1348
1349 void G1CollectorPolicy::print_heap_transition() const {
1350 print_heap_transition(_heap_used_bytes_before_gc);
1351 }
1352
1353 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1354 YoungList* young_list = _g1->young_list();
1355
1356 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1357 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1358 size_t heap_used_bytes_after_gc = _g1->used();
1359
1360 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1361 size_t eden_capacity_bytes_after_gc =
1362 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1363
1364 gclog_or_tty->print(
1365 " [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1366 "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1367 "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1368 EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1369 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1370 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1371 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1372 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1373 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1374 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1375 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1376 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1377 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1378 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1379
1380 if (full) {
1381 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1382 }
1383
1384 gclog_or_tty->cr();
1385 }
1386
1387 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1388 phase_times()->print(pause_time_sec);
1389 }
1390
1391 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1392 double update_rs_processed_buffers,
1393 double goal_ms) {
1394 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1395 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1396
1397 if (G1UseAdaptiveConcRefinement) {
1398 const int k_gy = 3, k_gr = 6;
1399 const double inc_k = 1.1, dec_k = 0.9;
1400
1401 int g = cg1r->green_zone();
1402 if (update_rs_time > goal_ms) {
1403 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1404 } else {
1405 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1406 g = (int)MAX2(g * inc_k, g + 1.0);
1407 }
1408 }
1409 // Change the refinement threads params
1410 cg1r->set_green_zone(g);
1411 cg1r->set_yellow_zone(g * k_gy);
1412 cg1r->set_red_zone(g * k_gr);
1413 cg1r->reinitialize_threads();
1414
1415 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1416 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1417 cg1r->yellow_zone());
1418 // Change the barrier params
1419 dcqs.set_process_completed_threshold(processing_threshold);
1420 dcqs.set_max_completed_queue(cg1r->red_zone());
1421 }
1422
1423 int curr_queue_size = dcqs.completed_buffers_num();
1424 if (curr_queue_size >= cg1r->yellow_zone()) {
1425 dcqs.set_completed_queue_padding(curr_queue_size);
1426 } else {
1427 dcqs.set_completed_queue_padding(0);
1428 }
1429 dcqs.notify_if_necessary();
1430 }
1431
1432 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1433 return (size_t) get_new_prediction(_rs_length_diff_seq);
1434 }
1435
1436 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1437 return get_new_prediction(_alloc_rate_ms_seq);
1438 }
1439
1440 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1441 return get_new_prediction(_cost_per_card_ms_seq);
1442 }
1443
1444 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1445 return get_new_prediction(_cost_scan_hcc_seq);
1446 }
1447
1448 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1449 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1450 }
1451
1452 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1453 return get_new_prediction(_young_cards_per_entry_ratio_seq);
1454 }
1455
1456 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1457 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1458 return predict_young_cards_per_entry_ratio();
1459 } else {
1460 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1461 }
1462 }
1463
1464 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1465 return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1466 }
1467
1468 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1469 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1470 }
1471
1472 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1473 if (collector_state()->gcs_are_young()) {
1474 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1475 } else {
1476 return predict_mixed_rs_scan_time_ms(card_num);
1477 }
1478 }
1479
1480 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1481 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1482 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1483 } else {
1484 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1485 }
1486 }
1487
1488 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1489 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1490 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1491 } else {
1492 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1493 }
1494 }
1495
1496 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1497 if (collector_state()->during_concurrent_mark()) {
1498 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1499 } else {
1500 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1501 }
1502 }
1503
1504 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1505 return get_new_prediction(_constant_other_time_ms_seq);
1506 }
1507
1508 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1509 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1510 }
1511
1512 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1513 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1514 }
1515
1516 double G1CollectorPolicy::predict_remark_time_ms() const {
1517 return get_new_prediction(_concurrent_mark_remark_times_ms);
1518 }
1519
1520 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1521 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1522 }
1523
1524 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1525 TruncatedSeq* seq = surv_rate_group->get_seq(age);
1526 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1527 double pred = get_new_prediction(seq);
1528 if (pred > 1.0) {
1529 pred = 1.0;
1530 }
1531 return pred;
1532 }
1533
1534 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1535 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1536 }
1537
1538 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1539 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1540 }
1541
1542 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1543 size_t scanned_cards) const {
1544 return
1545 predict_rs_update_time_ms(pending_cards) +
1546 predict_rs_scan_time_ms(scanned_cards) +
1547 predict_constant_other_time_ms();
1548 }
1549
1550 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1551 size_t rs_length = predict_rs_length_diff();
1552 size_t card_num;
1553 if (collector_state()->gcs_are_young()) {
1554 card_num = predict_young_card_num(rs_length);
1555 } else {
1556 card_num = predict_non_young_card_num(rs_length);
1557 }
1558 return predict_base_elapsed_time_ms(pending_cards, card_num);
1559 }
1560
1561 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1562 size_t bytes_to_copy;
1563 if (hr->is_marked())
1564 bytes_to_copy = hr->max_live_bytes();
1565 else {
1566 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1567 int age = hr->age_in_surv_rate_group();
1568 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1569 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1570 }
1571 return bytes_to_copy;
1572 }
1573
1574 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1575 bool for_young_gc) const {
1576 size_t rs_length = hr->rem_set()->occupied();
1577 size_t card_num;
1578
1579 // Predicting the number of cards is based on which type of GC
1580 // we're predicting for.
1581 if (for_young_gc) {
1582 card_num = predict_young_card_num(rs_length);
1583 } else {
1584 card_num = predict_non_young_card_num(rs_length);
1585 }
1586 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1587
1588 double region_elapsed_time_ms =
1589 predict_rs_scan_time_ms(card_num) +
1590 predict_object_copy_time_ms(bytes_to_copy);
1591
1592 // The prediction of the "other" time for this region is based
1593 // upon the region type and NOT the GC type.
1594 if (hr->is_young()) {
1595 region_elapsed_time_ms += predict_young_other_time_ms(1);
1596 } else {
1597 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1598 }
1599 return region_elapsed_time_ms;
1600 }
1601
1602 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1603 uint survivor_cset_region_length) {
1604 _eden_cset_region_length = eden_cset_region_length;
1605 _survivor_cset_region_length = survivor_cset_region_length;
1606 _old_cset_region_length = 0;
1607 }
1608
1609 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1610 _recorded_rs_lengths = rs_lengths;
1611 }
1612
1613 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1614 double elapsed_ms) {
1615 _recent_gc_times_ms->add(elapsed_ms);
1616 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1617 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1618 }
1619
1620 size_t G1CollectorPolicy::expansion_amount() const {
1621 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1622 double threshold = _gc_overhead_perc;
1623 if (recent_gc_overhead > threshold) {
1624 // We will double the existing space, or take
1625 // G1ExpandByPercentOfAvailable % of the available expansion
1626 // space, whichever is smaller, bounded below by a minimum
1627 // expansion (unless that's all that's left.)
1628 const size_t min_expand_bytes = 1*M;
1629 size_t reserved_bytes = _g1->max_capacity();
1630 size_t committed_bytes = _g1->capacity();
1631 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1632 size_t expand_bytes;
1633 size_t expand_bytes_via_pct =
1634 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1635 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1636 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1637 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1638
1639 ergo_verbose5(ErgoHeapSizing,
1640 "attempt heap expansion",
1641 ergo_format_reason("recent GC overhead higher than "
1642 "threshold after GC")
1643 ergo_format_perc("recent GC overhead")
1644 ergo_format_perc("threshold")
1645 ergo_format_byte("uncommitted")
1646 ergo_format_byte_perc("calculated expansion amount"),
1647 recent_gc_overhead, threshold,
1648 uncommitted_bytes,
1649 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1650
1651 return expand_bytes;
1652 } else {
1653 return 0;
1654 }
1655 }
1656
1657 void G1CollectorPolicy::print_tracing_info() const {
1658 _trace_young_gen_time_data.print();
1659 _trace_old_gen_time_data.print();
1660 }
1661
1662 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1663 #ifndef PRODUCT
1664 _short_lived_surv_rate_group->print_surv_rate_summary();
1665 // add this call for any other surv rate groups
1666 #endif // PRODUCT
1667 }
1668
1669 bool G1CollectorPolicy::is_young_list_full() const {
1670 uint young_list_length = _g1->young_list()->length();
1671 uint young_list_target_length = _young_list_target_length;
1672 return young_list_length >= young_list_target_length;
1673 }
1674
1675 bool G1CollectorPolicy::can_expand_young_list() const {
1676 uint young_list_length = _g1->young_list()->length();
1677 uint young_list_max_length = _young_list_max_length;
1678 return young_list_length < young_list_max_length;
1679 }
1680
1681 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1682 uint expansion_region_num = 0;
1683 if (GCLockerEdenExpansionPercent > 0) {
1684 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1685 double expansion_region_num_d = perc * (double) _young_list_target_length;
1686 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1687 // less than 1.0) we'll get 1.
1688 expansion_region_num = (uint) ceil(expansion_region_num_d);
1689 } else {
1690 assert(expansion_region_num == 0, "sanity");
1691 }
1692 _young_list_max_length = _young_list_target_length + expansion_region_num;
1693 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1694 }
1695
1696 // Calculates survivor space parameters.
1697 void G1CollectorPolicy::update_survivors_policy() {
1698 double max_survivor_regions_d =
1699 (double) _young_list_target_length / (double) SurvivorRatio;
1700 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1701 // smaller than 1.0) we'll get 1.
1702 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1703
1704 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1705 HeapRegion::GrainWords * _max_survivor_regions, counters());
1706 }
1707
1708 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1709 // We actually check whether we are marking here and not if we are in a
1710 // reclamation phase. This means that we will schedule a concurrent mark
1711 // even while we are still in the process of reclaiming memory.
1712 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1713 if (!during_cycle) {
1714 ergo_verbose1(ErgoConcCycles,
1715 "request concurrent cycle initiation",
1716 ergo_format_reason("requested by GC cause")
1717 ergo_format_str("GC cause"),
1718 GCCause::to_string(gc_cause));
1719 collector_state()->set_initiate_conc_mark_if_possible(true);
1720 return true;
1721 } else {
1722 ergo_verbose1(ErgoConcCycles,
1723 "do not request concurrent cycle initiation",
1724 ergo_format_reason("concurrent cycle already in progress")
1725 ergo_format_str("GC cause"),
1726 GCCause::to_string(gc_cause));
1727 return false;
1728 }
1729 }
1730
1731 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1732 // We are about to decide on whether this pause will be an
1733 // initial-mark pause.
1734
1735 // First, collector_state()->during_initial_mark_pause() should not be already set. We
1736 // will set it here if we have to. However, it should be cleared by
1737 // the end of the pause (it's only set for the duration of an
1738 // initial-mark pause).
1739 assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1740
1741 if (collector_state()->initiate_conc_mark_if_possible()) {
1742 // We had noticed on a previous pause that the heap occupancy has
1743 // gone over the initiating threshold and we should start a
1744 // concurrent marking cycle. So we might initiate one.
1745
1746 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1747 // Initiate a new initial mark only if there is no marking or reclamation going
1748 // on.
1749
1750 collector_state()->set_during_initial_mark_pause(true);
1751 // And we can now clear initiate_conc_mark_if_possible() as
1752 // we've already acted on it.
1753 collector_state()->set_initiate_conc_mark_if_possible(false);
1754
1755 ergo_verbose0(ErgoConcCycles,
1756 "initiate concurrent cycle",
1757 ergo_format_reason("concurrent cycle initiation requested"));
1758 } else {
1759 // The concurrent marking thread is still finishing up the
1760 // previous cycle. If we start one right now the two cycles
1761 // overlap. In particular, the concurrent marking thread might
1762 // be in the process of clearing the next marking bitmap (which
1763 // we will use for the next cycle if we start one). Starting a
1764 // cycle now will be bad given that parts of the marking
1765 // information might get cleared by the marking thread. And we
1766 // cannot wait for the marking thread to finish the cycle as it
1767 // periodically yields while clearing the next marking bitmap
1768 // and, if it's in a yield point, it's waiting for us to
1769 // finish. So, at this point we will not start a cycle and we'll
1770 // let the concurrent marking thread complete the last one.
1771 ergo_verbose0(ErgoConcCycles,
1772 "do not initiate concurrent cycle",
1773 ergo_format_reason("concurrent cycle already in progress"));
1774 }
1775 }
1776 }
1777
1778 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1779 G1CollectedHeap* _g1h;
1780 CSetChooserParUpdater _cset_updater;
1781
1782 public:
1783 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1784 uint chunk_size) :
1785 _g1h(G1CollectedHeap::heap()),
1786 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1787
1788 bool doHeapRegion(HeapRegion* r) {
1789 // Do we have any marking information for this region?
1790 if (r->is_marked()) {
1791 // We will skip any region that's currently used as an old GC
1792 // alloc region (we should not consider those for collection
1793 // before we fill them up).
1794 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1795 _cset_updater.add_region(r);
1796 }
1797 }
1798 return false;
1799 }
1800 };
1801
1802 class ParKnownGarbageTask: public AbstractGangTask {
1803 CollectionSetChooser* _hrSorted;
1804 uint _chunk_size;
1805 G1CollectedHeap* _g1;
1806 HeapRegionClaimer _hrclaimer;
1807
1808 public:
1809 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1810 AbstractGangTask("ParKnownGarbageTask"),
1811 _hrSorted(hrSorted), _chunk_size(chunk_size),
1812 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1813
1814 void work(uint worker_id) {
1815 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1816 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1817 }
1818 };
1819
1820 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1821 assert(n_workers > 0, "Active gc workers should be greater than 0");
1822 const uint overpartition_factor = 4;
1823 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1824 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1825 }
1826
1827 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1828 _collectionSetChooser->clear();
1829
1830 WorkGang* workers = _g1->workers();
1831 uint n_workers = workers->active_workers();
1832
1833 uint n_regions = _g1->num_regions();
1834 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1835 _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1836 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1837 workers->run_task(&par_known_garbage_task);
1838
1839 _collectionSetChooser->sort_regions();
1840
1841 double end_sec = os::elapsedTime();
1842 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1843 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1844 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1845 _prev_collection_pause_end_ms += elapsed_time_ms;
1846
1847 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1848 }
1849
1850 // Add the heap region at the head of the non-incremental collection set
1851 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1852 assert(_inc_cset_build_state == Active, "Precondition");
1853 assert(hr->is_old(), "the region should be old");
1854
1855 assert(!hr->in_collection_set(), "should not already be in the CSet");
1856 _g1->register_old_region_with_cset(hr);
1857 hr->set_next_in_collection_set(_collection_set);
1858 _collection_set = hr;
1859 _collection_set_bytes_used_before += hr->used();
1860 size_t rs_length = hr->rem_set()->occupied();
1861 _recorded_rs_lengths += rs_length;
1862 _old_cset_region_length += 1;
1863 }
1864
1865 // Initialize the per-collection-set information
1866 void G1CollectorPolicy::start_incremental_cset_building() {
1867 assert(_inc_cset_build_state == Inactive, "Precondition");
1868
1869 _inc_cset_head = NULL;
1870 _inc_cset_tail = NULL;
1871 _inc_cset_bytes_used_before = 0;
1872
1873 _inc_cset_max_finger = 0;
1874 _inc_cset_recorded_rs_lengths = 0;
1875 _inc_cset_recorded_rs_lengths_diffs = 0;
1876 _inc_cset_predicted_elapsed_time_ms = 0.0;
1877 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1878 _inc_cset_build_state = Active;
1879 }
1880
1881 void G1CollectorPolicy::finalize_incremental_cset_building() {
1882 assert(_inc_cset_build_state == Active, "Precondition");
1883 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1884
1885 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1886 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1887 // that adds a new region to the CSet. Further updates by the
1888 // concurrent refinement thread that samples the young RSet lengths
1889 // are accumulated in the *_diffs fields. Here we add the diffs to
1890 // the "main" fields.
1891
1892 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1893 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1894 } else {
1895 // This is defensive. The diff should in theory be always positive
1896 // as RSets can only grow between GCs. However, given that we
1897 // sample their size concurrently with other threads updating them
1898 // it's possible that we might get the wrong size back, which
1899 // could make the calculations somewhat inaccurate.
1900 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1901 if (_inc_cset_recorded_rs_lengths >= diffs) {
1902 _inc_cset_recorded_rs_lengths -= diffs;
1903 } else {
1904 _inc_cset_recorded_rs_lengths = 0;
1905 }
1906 }
1907 _inc_cset_predicted_elapsed_time_ms +=
1908 _inc_cset_predicted_elapsed_time_ms_diffs;
1909
1910 _inc_cset_recorded_rs_lengths_diffs = 0;
1911 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1912 }
1913
1914 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1915 // This routine is used when:
1916 // * adding survivor regions to the incremental cset at the end of an
1917 // evacuation pause,
1918 // * adding the current allocation region to the incremental cset
1919 // when it is retired, and
1920 // * updating existing policy information for a region in the
1921 // incremental cset via young list RSet sampling.
1922 // Therefore this routine may be called at a safepoint by the
1923 // VM thread, or in-between safepoints by mutator threads (when
1924 // retiring the current allocation region) or a concurrent
1925 // refine thread (RSet sampling).
1926
1927 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1928 size_t used_bytes = hr->used();
1929 _inc_cset_recorded_rs_lengths += rs_length;
1930 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1931 _inc_cset_bytes_used_before += used_bytes;
1932
1933 // Cache the values we have added to the aggregated information
1934 // in the heap region in case we have to remove this region from
1935 // the incremental collection set, or it is updated by the
1936 // rset sampling code
1937 hr->set_recorded_rs_length(rs_length);
1938 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1939 }
1940
1941 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1942 size_t new_rs_length) {
1943 // Update the CSet information that is dependent on the new RS length
1944 assert(hr->is_young(), "Precondition");
1945 assert(!SafepointSynchronize::is_at_safepoint(),
1946 "should not be at a safepoint");
1947
1948 // We could have updated _inc_cset_recorded_rs_lengths and
1949 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1950 // that atomically, as this code is executed by a concurrent
1951 // refinement thread, potentially concurrently with a mutator thread
1952 // allocating a new region and also updating the same fields. To
1953 // avoid the atomic operations we accumulate these updates on two
1954 // separate fields (*_diffs) and we'll just add them to the "main"
1955 // fields at the start of a GC.
1956
1957 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1958 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1959 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1960
1961 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1962 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1963 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1964 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1965
1966 hr->set_recorded_rs_length(new_rs_length);
1967 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1968 }
1969
1970 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1971 assert(hr->is_young(), "invariant");
1972 assert(hr->young_index_in_cset() > -1, "should have already been set");
1973 assert(_inc_cset_build_state == Active, "Precondition");
1974
1975 // We need to clear and set the cached recorded/cached collection set
1976 // information in the heap region here (before the region gets added
1977 // to the collection set). An individual heap region's cached values
1978 // are calculated, aggregated with the policy collection set info,
1979 // and cached in the heap region here (initially) and (subsequently)
1980 // by the Young List sampling code.
1981
1982 size_t rs_length = hr->rem_set()->occupied();
1983 add_to_incremental_cset_info(hr, rs_length);
1984
1985 HeapWord* hr_end = hr->end();
1986 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1987
1988 assert(!hr->in_collection_set(), "invariant");
1989 _g1->register_young_region_with_cset(hr);
1990 assert(hr->next_in_collection_set() == NULL, "invariant");
1991 }
1992
1993 // Add the region at the RHS of the incremental cset
1994 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1995 // We should only ever be appending survivors at the end of a pause
1996 assert(hr->is_survivor(), "Logic");
1997
1998 // Do the 'common' stuff
1999 add_region_to_incremental_cset_common(hr);
2000
2001 // Now add the region at the right hand side
2002 if (_inc_cset_tail == NULL) {
2003 assert(_inc_cset_head == NULL, "invariant");
2004 _inc_cset_head = hr;
2005 } else {
2006 _inc_cset_tail->set_next_in_collection_set(hr);
2007 }
2008 _inc_cset_tail = hr;
2009 }
2010
2011 // Add the region to the LHS of the incremental cset
2012 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2013 // Survivors should be added to the RHS at the end of a pause
2014 assert(hr->is_eden(), "Logic");
2015
2016 // Do the 'common' stuff
2017 add_region_to_incremental_cset_common(hr);
2018
2019 // Add the region at the left hand side
2020 hr->set_next_in_collection_set(_inc_cset_head);
2021 if (_inc_cset_head == NULL) {
2022 assert(_inc_cset_tail == NULL, "Invariant");
2023 _inc_cset_tail = hr;
2024 }
2025 _inc_cset_head = hr;
2026 }
2027
2028 #ifndef PRODUCT
2029 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2030 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2031
2032 st->print_cr("\nCollection_set:");
2033 HeapRegion* csr = list_head;
2034 while (csr != NULL) {
2035 HeapRegion* next = csr->next_in_collection_set();
2036 assert(csr->in_collection_set(), "bad CS");
2037 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2038 HR_FORMAT_PARAMS(csr),
2039 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2040 csr->age_in_surv_rate_group_cond());
2041 csr = next;
2042 }
2043 }
2044 #endif // !PRODUCT
2045
2046 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2047 // Returns the given amount of reclaimable bytes (that represents
2048 // the amount of reclaimable space still to be collected) as a
2049 // percentage of the current heap capacity.
2050 size_t capacity_bytes = _g1->capacity();
2051 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2052 }
2053
2054 void G1CollectorPolicy::maybe_start_marking() {
2055 if (need_to_start_conc_mark("end of GC")) {
2056 // Note: this might have already been set, if during the last
2057 // pause we decided to start a cycle but at the beginning of
2058 // this pause we decided to postpone it. That's OK.
2059 collector_state()->set_initiate_conc_mark_if_possible(true);
2060 }
2061 }
2062
2063 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2064 assert(!collector_state()->full_collection(), "must be");
2065 if (collector_state()->during_initial_mark_pause()) {
2066 assert(collector_state()->last_gc_was_young(), "must be");
2067 assert(!collector_state()->last_young_gc(), "must be");
2068 return InitialMarkGC;
2069 } else if (collector_state()->last_young_gc()) {
2070 assert(!collector_state()->during_initial_mark_pause(), "must be");
2071 assert(collector_state()->last_gc_was_young(), "must be");
2072 return LastYoungGC;
2073 } else if (!collector_state()->last_gc_was_young()) {
2074 assert(!collector_state()->during_initial_mark_pause(), "must be");
2075 assert(!collector_state()->last_young_gc(), "must be");
2076 return MixedGC;
2077 } else {
2078 assert(collector_state()->last_gc_was_young(), "must be");
2079 assert(!collector_state()->during_initial_mark_pause(), "must be");
2080 assert(!collector_state()->last_young_gc(), "must be");
2081 return YoungOnlyGC;
2082 }
2083 }
2084
2085 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2086 // Manage the MMU tracker. For some reason it ignores Full GCs.
2087 if (kind != FullGC) {
2088 _mmu_tracker->add_pause(start, end);
2089 }
2090 // Manage the mutator time tracking from initial mark to first mixed gc.
2091 switch (kind) {
2092 case FullGC:
2093 abort_time_to_mixed_tracking();
2094 break;
2095 case Cleanup:
2096 case Remark:
2097 case YoungOnlyGC:
2098 case LastYoungGC:
2099 _initial_mark_to_mixed.add_pause(end - start);
2100 break;
2101 case InitialMarkGC:
2102 _initial_mark_to_mixed.record_initial_mark_end(end);
2103 break;
2104 case MixedGC:
2105 _initial_mark_to_mixed.record_mixed_gc_start(start);
2106 break;
2107 default:
2108 ShouldNotReachHere();
2109 }
2110 }
2111
2112 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2113 _initial_mark_to_mixed.reset();
2114 }
2115
2116 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2117 const char* false_action_str) const {
2118 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2119 if (cset_chooser->is_empty()) {
2120 ergo_verbose0(ErgoMixedGCs,
2121 false_action_str,
2122 ergo_format_reason("candidate old regions not available"));
2123 return false;
2124 }
2125
2126 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2127 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2128 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2129 double threshold = (double) G1HeapWastePercent;
2130 if (reclaimable_perc <= threshold) {
2131 ergo_verbose4(ErgoMixedGCs,
2132 false_action_str,
2133 ergo_format_reason("reclaimable percentage not over threshold")
2134 ergo_format_region("candidate old regions")
2135 ergo_format_byte_perc("reclaimable")
2136 ergo_format_perc("threshold"),
2137 cset_chooser->remaining_regions(),
2138 reclaimable_bytes,
2139 reclaimable_perc, threshold);
2140 return false;
2141 }
2142
2143 ergo_verbose4(ErgoMixedGCs,
2144 true_action_str,
2145 ergo_format_reason("candidate old regions available")
2146 ergo_format_region("candidate old regions")
2147 ergo_format_byte_perc("reclaimable")
2148 ergo_format_perc("threshold"),
2149 cset_chooser->remaining_regions(),
2150 reclaimable_bytes,
2151 reclaimable_perc, threshold);
2152 return true;
2153 }
2154
2155 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2156 // The min old CSet region bound is based on the maximum desired
2157 // number of mixed GCs after a cycle. I.e., even if some old regions
2158 // look expensive, we should add them to the CSet anyway to make
2159 // sure we go through the available old regions in no more than the
2160 // maximum desired number of mixed GCs.
2161 //
2162 // The calculation is based on the number of marked regions we added
2163 // to the CSet chooser in the first place, not how many remain, so
2164 // that the result is the same during all mixed GCs that follow a cycle.
2165
2166 const size_t region_num = (size_t) _collectionSetChooser->length();
2167 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2168 size_t result = region_num / gc_num;
2169 // emulate ceiling
2170 if (result * gc_num < region_num) {
2171 result += 1;
2172 }
2173 return (uint) result;
2174 }
2175
2176 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2177 // The max old CSet region bound is based on the threshold expressed
2178 // as a percentage of the heap size. I.e., it should bound the
2179 // number of old regions added to the CSet irrespective of how many
2180 // of them are available.
2181
2182 const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2183 const size_t region_num = g1h->num_regions();
2184 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2185 size_t result = region_num * perc / 100;
2186 // emulate ceiling
2187 if (100 * result < region_num * perc) {
2188 result += 1;
2189 }
2190 return (uint) result;
2191 }
2192
2193
2194 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2195 double young_start_time_sec = os::elapsedTime();
2196
2197 YoungList* young_list = _g1->young_list();
2198 finalize_incremental_cset_building();
2199
2200 guarantee(target_pause_time_ms > 0.0,
2201 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2202 guarantee(_collection_set == NULL, "Precondition");
2203
2204 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2205 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2206
2207 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2208 "start choosing CSet",
2209 ergo_format_size("_pending_cards")
2210 ergo_format_ms("predicted base time")
2211 ergo_format_ms("remaining time")
2212 ergo_format_ms("target pause time"),
2213 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2214
2215 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2216
2217 if (collector_state()->last_gc_was_young()) {
2218 _trace_young_gen_time_data.increment_young_collection_count();
2219 } else {
2220 _trace_young_gen_time_data.increment_mixed_collection_count();
2221 }
2222
2223 // The young list is laid with the survivor regions from the previous
2224 // pause are appended to the RHS of the young list, i.e.
2225 // [Newly Young Regions ++ Survivors from last pause].
2226
2227 uint survivor_region_length = young_list->survivor_length();
2228 uint eden_region_length = young_list->eden_length();
2229 init_cset_region_lengths(eden_region_length, survivor_region_length);
2230
2231 HeapRegion* hr = young_list->first_survivor_region();
2232 while (hr != NULL) {
2233 assert(hr->is_survivor(), "badly formed young list");
2234 // There is a convention that all the young regions in the CSet
2235 // are tagged as "eden", so we do this for the survivors here. We
2236 // use the special set_eden_pre_gc() as it doesn't check that the
2237 // region is free (which is not the case here).
2238 hr->set_eden_pre_gc();
2239 hr = hr->get_next_young_region();
2240 }
2241
2242 // Clear the fields that point to the survivor list - they are all young now.
2243 young_list->clear_survivors();
2244
2245 _collection_set = _inc_cset_head;
2246 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2247 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2248
2249 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2250 "add young regions to CSet",
2251 ergo_format_region("eden")
2252 ergo_format_region("survivors")
2253 ergo_format_ms("predicted young region time")
2254 ergo_format_ms("target pause time"),
2255 eden_region_length, survivor_region_length,
2256 _inc_cset_predicted_elapsed_time_ms,
2257 target_pause_time_ms);
2258
2259 // The number of recorded young regions is the incremental
2260 // collection set's current size
2261 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2262
2263 double young_end_time_sec = os::elapsedTime();
2264 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2265
2266 return time_remaining_ms;
2267 }
2268
2269 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2270 double non_young_start_time_sec = os::elapsedTime();
2271 double predicted_old_time_ms = 0.0;
2272
2273
2274 if (!collector_state()->gcs_are_young()) {
2275 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2276 cset_chooser->verify();
2277 const uint min_old_cset_length = calc_min_old_cset_length();
2278 const uint max_old_cset_length = calc_max_old_cset_length();
2279
2280 uint expensive_region_num = 0;
2281 bool check_time_remaining = adaptive_young_list_length();
2282
2283 HeapRegion* hr = cset_chooser->peek();
2284 while (hr != NULL) {
2285 if (old_cset_region_length() >= max_old_cset_length) {
2286 // Added maximum number of old regions to the CSet.
2287 ergo_verbose2(ErgoCSetConstruction,
2288 "finish adding old regions to CSet",
2289 ergo_format_reason("old CSet region num reached max")
2290 ergo_format_region("old")
2291 ergo_format_region("max"),
2292 old_cset_region_length(), max_old_cset_length);
2293 break;
2294 }
2295
2296
2297 // Stop adding regions if the remaining reclaimable space is
2298 // not above G1HeapWastePercent.
2299 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2300 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2301 double threshold = (double) G1HeapWastePercent;
2302 if (reclaimable_perc <= threshold) {
2303 // We've added enough old regions that the amount of uncollected
2304 // reclaimable space is at or below the waste threshold. Stop
2305 // adding old regions to the CSet.
2306 ergo_verbose5(ErgoCSetConstruction,
2307 "finish adding old regions to CSet",
2308 ergo_format_reason("reclaimable percentage not over threshold")
2309 ergo_format_region("old")
2310 ergo_format_region("max")
2311 ergo_format_byte_perc("reclaimable")
2312 ergo_format_perc("threshold"),
2313 old_cset_region_length(),
2314 max_old_cset_length,
2315 reclaimable_bytes,
2316 reclaimable_perc, threshold);
2317 break;
2318 }
2319
2320 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2321 if (check_time_remaining) {
2322 if (predicted_time_ms > time_remaining_ms) {
2323 // Too expensive for the current CSet.
2324
2325 if (old_cset_region_length() >= min_old_cset_length) {
2326 // We have added the minimum number of old regions to the CSet,
2327 // we are done with this CSet.
2328 ergo_verbose4(ErgoCSetConstruction,
2329 "finish adding old regions to CSet",
2330 ergo_format_reason("predicted time is too high")
2331 ergo_format_ms("predicted time")
2332 ergo_format_ms("remaining time")
2333 ergo_format_region("old")
2334 ergo_format_region("min"),
2335 predicted_time_ms, time_remaining_ms,
2336 old_cset_region_length(), min_old_cset_length);
2337 break;
2338 }
2339
2340 // We'll add it anyway given that we haven't reached the
2341 // minimum number of old regions.
2342 expensive_region_num += 1;
2343 }
2344 } else {
2345 if (old_cset_region_length() >= min_old_cset_length) {
2346 // In the non-auto-tuning case, we'll finish adding regions
2347 // to the CSet if we reach the minimum.
2348 ergo_verbose2(ErgoCSetConstruction,
2349 "finish adding old regions to CSet",
2350 ergo_format_reason("old CSet region num reached min")
2351 ergo_format_region("old")
2352 ergo_format_region("min"),
2353 old_cset_region_length(), min_old_cset_length);
2354 break;
2355 }
2356 }
2357
2358 // We will add this region to the CSet.
2359 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2360 predicted_old_time_ms += predicted_time_ms;
2361 cset_chooser->pop(); // already have region via peek()
2362 _g1->old_set_remove(hr);
2363 add_old_region_to_cset(hr);
2364
2365 hr = cset_chooser->peek();
2366 }
2367 if (hr == NULL) {
2368 ergo_verbose0(ErgoCSetConstruction,
2369 "finish adding old regions to CSet",
2370 ergo_format_reason("candidate old regions not available"));
2371 }
2372
2373 if (expensive_region_num > 0) {
2374 // We print the information once here at the end, predicated on
2375 // whether we added any apparently expensive regions or not, to
2376 // avoid generating output per region.
2377 ergo_verbose4(ErgoCSetConstruction,
2378 "added expensive regions to CSet",
2379 ergo_format_reason("old CSet region num not reached min")
2380 ergo_format_region("old")
2381 ergo_format_region("expensive")
2382 ergo_format_region("min")
2383 ergo_format_ms("remaining time"),
2384 old_cset_region_length(),
2385 expensive_region_num,
2386 min_old_cset_length,
2387 time_remaining_ms);
2388 }
2389
2390 cset_chooser->verify();
2391 }
2392
2393 stop_incremental_cset_building();
2394
2395 ergo_verbose3(ErgoCSetConstruction,
2396 "finish choosing CSet",
2397 ergo_format_region("old")
2398 ergo_format_ms("predicted old region time")
2399 ergo_format_ms("time remaining"),
2400 old_cset_region_length(),
2401 predicted_old_time_ms, time_remaining_ms);
2402
2403 double non_young_end_time_sec = os::elapsedTime();
2404 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2405 }
2406
2407 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2408 if(TraceYoungGenTime) {
2409 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2410 }
2411 }
2412
2413 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2414 if(TraceYoungGenTime) {
2415 _all_yield_times_ms.add(yield_time_ms);
2416 }
2417 }
2418
2419 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2420 if(TraceYoungGenTime) {
2421 _total.add(pause_time_ms);
2422 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2423 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2424 _parallel.add(phase_times->cur_collection_par_time_ms());
2425 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2426 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2427 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2428 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2429 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2430 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2431
2432 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2433 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2434 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2435 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2436 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2437 phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2438
2439 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2440 _parallel_other.add(parallel_other_time);
2441 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2442 }
2443 }
2444
2445 void TraceYoungGenTimeData::increment_young_collection_count() {
2446 if(TraceYoungGenTime) {
2447 ++_young_pause_num;
2448 }
2449 }
2450
2451 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2452 if(TraceYoungGenTime) {
2453 ++_mixed_pause_num;
2454 }
2455 }
2456
2457 void TraceYoungGenTimeData::print_summary(const char* str,
2458 const NumberSeq* seq) const {
2459 double sum = seq->sum();
2460 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2461 str, sum / 1000.0, seq->avg());
2462 }
2463
2464 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2465 const NumberSeq* seq) const {
2466 print_summary(str, seq);
2467 gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2468 "(num", seq->num(), seq->sd(), seq->maximum());
2469 }
2470
2471 void TraceYoungGenTimeData::print() const {
2472 if (!TraceYoungGenTime) {
2473 return;
2474 }
2475
2476 gclog_or_tty->print_cr("ALL PAUSES");
2477 print_summary_sd(" Total", &_total);
2478 gclog_or_tty->cr();
2479 gclog_or_tty->cr();
2480 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2481 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2482 gclog_or_tty->cr();
2483
2484 gclog_or_tty->print_cr("EVACUATION PAUSES");
2485
2486 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2487 gclog_or_tty->print_cr("none");
2488 } else {
2489 print_summary_sd(" Evacuation Pauses", &_total);
2490 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2491 print_summary(" Parallel Time", &_parallel);
2492 print_summary(" Ext Root Scanning", &_ext_root_scan);
2493 print_summary(" SATB Filtering", &_satb_filtering);
2494 print_summary(" Update RS", &_update_rs);
2495 print_summary(" Scan RS", &_scan_rs);
2496 print_summary(" Object Copy", &_obj_copy);
2497 print_summary(" Termination", &_termination);
2498 print_summary(" Parallel Other", &_parallel_other);
2499 print_summary(" Clear CT", &_clear_ct);
2500 print_summary(" Other", &_other);
2501 }
2502 gclog_or_tty->cr();
2503
2504 gclog_or_tty->print_cr("MISC");
2505 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2506 print_summary_sd(" Yields", &_all_yield_times_ms);
2507 }
2508
2509 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2510 if (TraceOldGenTime) {
2511 _all_full_gc_times.add(full_gc_time_ms);
2512 }
2513 }
2514
2515 void TraceOldGenTimeData::print() const {
2516 if (!TraceOldGenTime) {
2517 return;
2518 }
2519
2520 if (_all_full_gc_times.num() > 0) {
2521 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2522 _all_full_gc_times.num(),
2523 _all_full_gc_times.sum() / 1000.0);
2524 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2525 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2526 _all_full_gc_times.sd(),
2527 _all_full_gc_times.maximum());
2528 }
2529 }