1 /*
2 * Copyright (c) 2001, 2016, 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/concurrentMarkThread.inline.hpp"
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/g1CollectorPolicy.hpp"
30 #include "gc/g1/g1ConcurrentMark.hpp"
31 #include "gc/g1/g1IHOPControl.hpp"
32 #include "gc/g1/g1GCPhaseTimes.hpp"
33 #include "gc/g1/heapRegion.inline.hpp"
34 #include "gc/g1/heapRegionRemSet.hpp"
35 #include "gc/shared/gcPolicyCounters.hpp"
36 #include "runtime/arguments.hpp"
37 #include "runtime/java.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "utilities/debug.hpp"
40 #include "utilities/pair.hpp"
41
42 // Different defaults for different number of GC threads
43 // They were chosen by running GCOld and SPECjbb on debris with different
44 // numbers of GC threads and choosing them based on the results
45
46 // all the same
47 static double rs_length_diff_defaults[] = {
48 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
49 };
50
51 static double cost_per_card_ms_defaults[] = {
52 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
53 };
54
55 // all the same
56 static double young_cards_per_entry_ratio_defaults[] = {
57 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
58 };
59
60 static double cost_per_entry_ms_defaults[] = {
61 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
62 };
63
64 static double cost_per_byte_ms_defaults[] = {
65 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
66 };
67
68 // these should be pretty consistent
69 static double constant_other_time_ms_defaults[] = {
70 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
71 };
72
73
74 static double young_other_cost_per_region_ms_defaults[] = {
75 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
76 };
77
78 static double non_young_other_cost_per_region_ms_defaults[] = {
79 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
80 };
81
82 G1CollectorPolicy::G1CollectorPolicy() :
83 _predictor(G1ConfidencePercent / 100.0),
84 _parallel_gc_threads(ParallelGCThreads),
85
86 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
87 _stop_world_start(0.0),
88
89 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
90 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
91
92 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
93 _prev_collection_pause_end_ms(0.0),
94 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
95 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
96 _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
97 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
104 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
105 _non_young_other_cost_per_region_ms_seq(
106 new TruncatedSeq(TruncatedSeqLength)),
107
108 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
109 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
110
111 _pause_time_target_ms((double) MaxGCPauseMillis),
112
113 _recent_prev_end_times_for_all_gcs_sec(
114 new TruncatedSeq(NumPrevPausesForHeuristics)),
115
116 _recent_avg_pause_time_ratio(0.0),
117 _rs_lengths_prediction(0),
118 _max_survivor_regions(0),
119
120 _eden_cset_region_length(0),
121 _survivor_cset_region_length(0),
122 _old_cset_region_length(0),
123
124 _collection_set(NULL),
125 _collection_set_bytes_used_before(0),
126
127 // Incremental CSet attributes
128 _inc_cset_build_state(Inactive),
129 _inc_cset_head(NULL),
130 _inc_cset_tail(NULL),
131 _inc_cset_bytes_used_before(0),
132 _inc_cset_max_finger(NULL),
133 _inc_cset_recorded_rs_lengths(0),
134 _inc_cset_recorded_rs_lengths_diffs(0),
135 _inc_cset_predicted_elapsed_time_ms(0.0),
136 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
137
138 // add here any more surv rate groups
139 _recorded_survivor_regions(0),
140 _recorded_survivor_head(NULL),
141 _recorded_survivor_tail(NULL),
142 _survivors_age_table(true),
143
144 _gc_overhead_perc(0.0),
145
146 _bytes_allocated_in_old_since_last_gc(0),
147 _ihop_control(NULL),
148 _initial_mark_to_mixed() {
149
150 // SurvRateGroups below must be initialized after the predictor because they
151 // indirectly use it through this object passed to their constructor.
152 _short_lived_surv_rate_group =
153 new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
154 _survivor_surv_rate_group =
155 new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
156
157 // Set up the region size and associated fields. Given that the
158 // policy is created before the heap, we have to set this up here,
159 // so it's done as soon as possible.
160
161 // It would have been natural to pass initial_heap_byte_size() and
162 // max_heap_byte_size() to setup_heap_region_size() but those have
163 // not been set up at this point since they should be aligned with
164 // the region size. So, there is a circular dependency here. We base
165 // the region size on the heap size, but the heap size should be
166 // aligned with the region size. To get around this we use the
167 // unaligned values for the heap.
168 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
169 HeapRegionRemSet::setup_remset_size();
170
171 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
172 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
173 clear_ratio_check_data();
174
175 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
176
177 int index = MIN2(_parallel_gc_threads - 1, 7);
178
179 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
180 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
181 _cost_scan_hcc_seq->add(0.0);
182 _young_cards_per_entry_ratio_seq->add(
183 young_cards_per_entry_ratio_defaults[index]);
184 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
185 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
186 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
187 _young_other_cost_per_region_ms_seq->add(
188 young_other_cost_per_region_ms_defaults[index]);
189 _non_young_other_cost_per_region_ms_seq->add(
190 non_young_other_cost_per_region_ms_defaults[index]);
191
192 // Below, we might need to calculate the pause time target based on
193 // the pause interval. When we do so we are going to give G1 maximum
194 // flexibility and allow it to do pauses when it needs to. So, we'll
195 // arrange that the pause interval to be pause time target + 1 to
196 // ensure that a) the pause time target is maximized with respect to
197 // the pause interval and b) we maintain the invariant that pause
198 // time target < pause interval. If the user does not want this
199 // maximum flexibility, they will have to set the pause interval
200 // explicitly.
201
202 // First make sure that, if either parameter is set, its value is
203 // reasonable.
204 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
205 if (MaxGCPauseMillis < 1) {
206 vm_exit_during_initialization("MaxGCPauseMillis should be "
207 "greater than 0");
208 }
209 }
210 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
211 if (GCPauseIntervalMillis < 1) {
212 vm_exit_during_initialization("GCPauseIntervalMillis should be "
213 "greater than 0");
214 }
215 }
216
217 // Then, if the pause time target parameter was not set, set it to
218 // the default value.
219 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
220 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
221 // The default pause time target in G1 is 200ms
222 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
223 } else {
224 // We do not allow the pause interval to be set without the
225 // pause time target
226 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
227 "without setting MaxGCPauseMillis");
228 }
229 }
230
231 // Then, if the interval parameter was not set, set it according to
232 // the pause time target (this will also deal with the case when the
233 // pause time target is the default value).
234 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
235 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
236 }
237
238 // Finally, make sure that the two parameters are consistent.
239 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
240 char buffer[256];
241 jio_snprintf(buffer, 256,
242 "MaxGCPauseMillis (%u) should be less than "
243 "GCPauseIntervalMillis (%u)",
244 MaxGCPauseMillis, GCPauseIntervalMillis);
245 vm_exit_during_initialization(buffer);
246 }
247
248 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
249 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
250 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
251
252 // start conservatively (around 50ms is about right)
253 _concurrent_mark_remark_times_ms->add(0.05);
254 _concurrent_mark_cleanup_times_ms->add(0.20);
255 _tenuring_threshold = MaxTenuringThreshold;
256
257 assert(GCTimeRatio > 0,
258 "we should have set it to a default value set_g1_gc_flags() "
259 "if a user set it to 0");
260 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
261
262 uintx reserve_perc = G1ReservePercent;
263 // Put an artificial ceiling on this so that it's not set to a silly value.
264 if (reserve_perc > 50) {
265 reserve_perc = 50;
266 warning("G1ReservePercent is set to a value that is too large, "
267 "it's been updated to " UINTX_FORMAT, reserve_perc);
268 }
269 _reserve_factor = (double) reserve_perc / 100.0;
270 // This will be set when the heap is expanded
271 // for the first time during initialization.
272 _reserve_regions = 0;
273
274 _cset_chooser = new CollectionSetChooser();
275 }
276
277 G1CollectorPolicy::~G1CollectorPolicy() {
278 delete _ihop_control;
279 }
280
281 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
282 return _predictor.get_new_prediction(seq);
283 }
284
285 size_t G1CollectorPolicy::get_new_size_prediction(TruncatedSeq const* seq) const {
286 return (size_t)get_new_prediction(seq);
287 }
288
289 void G1CollectorPolicy::initialize_alignments() {
290 _space_alignment = HeapRegion::GrainBytes;
291 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
292 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
293 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
294 }
295
296 void G1CollectorPolicy::initialize_flags() {
297 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
298 FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
299 }
300
301 if (SurvivorRatio < 1) {
302 vm_exit_during_initialization("Invalid survivor ratio specified");
303 }
304 CollectorPolicy::initialize_flags();
305 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
306 }
307
308 void G1CollectorPolicy::post_heap_initialize() {
309 uintx max_regions = G1CollectedHeap::heap()->max_regions();
310 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
311 if (max_young_size != MaxNewSize) {
312 FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
313 }
314
315 _ihop_control = create_ihop_control();
316 }
317
318 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
319
320 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
321 _min_desired_young_length(0), _max_desired_young_length(0) {
322 if (FLAG_IS_CMDLINE(NewRatio)) {
323 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
324 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
325 } else {
326 _sizer_kind = SizerNewRatio;
327 _adaptive_size = false;
328 return;
329 }
330 }
331
332 if (NewSize > MaxNewSize) {
333 if (FLAG_IS_CMDLINE(MaxNewSize)) {
334 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
335 "A new max generation size of " SIZE_FORMAT "k will be used.",
336 NewSize/K, MaxNewSize/K, NewSize/K);
337 }
338 MaxNewSize = NewSize;
339 }
340
341 if (FLAG_IS_CMDLINE(NewSize)) {
342 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
343 1U);
344 if (FLAG_IS_CMDLINE(MaxNewSize)) {
345 _max_desired_young_length =
346 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
347 1U);
348 _sizer_kind = SizerMaxAndNewSize;
349 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
350 } else {
351 _sizer_kind = SizerNewSizeOnly;
352 }
353 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
354 _max_desired_young_length =
355 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
356 1U);
357 _sizer_kind = SizerMaxNewSizeOnly;
358 }
359 }
360
361 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
362 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
363 return MAX2(1U, default_value);
364 }
365
366 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
367 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
368 return MAX2(1U, default_value);
369 }
370
371 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
372 assert(number_of_heap_regions > 0, "Heap must be initialized");
373
374 switch (_sizer_kind) {
375 case SizerDefaults:
376 *min_young_length = calculate_default_min_length(number_of_heap_regions);
377 *max_young_length = calculate_default_max_length(number_of_heap_regions);
378 break;
379 case SizerNewSizeOnly:
380 *max_young_length = calculate_default_max_length(number_of_heap_regions);
381 *max_young_length = MAX2(*min_young_length, *max_young_length);
382 break;
383 case SizerMaxNewSizeOnly:
384 *min_young_length = calculate_default_min_length(number_of_heap_regions);
385 *min_young_length = MIN2(*min_young_length, *max_young_length);
386 break;
387 case SizerMaxAndNewSize:
388 // Do nothing. Values set on the command line, don't update them at runtime.
389 break;
390 case SizerNewRatio:
391 *min_young_length = number_of_heap_regions / (NewRatio + 1);
392 *max_young_length = *min_young_length;
393 break;
394 default:
395 ShouldNotReachHere();
396 }
397
398 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
399 }
400
401 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
402 // We need to pass the desired values because recalculation may not update these
403 // values in some cases.
404 uint temp = _min_desired_young_length;
405 uint result = _max_desired_young_length;
406 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
407 return result;
408 }
409
410 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
411 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
412 &_max_desired_young_length);
413 }
414
415 void G1CollectorPolicy::init() {
416 // Set aside an initial future to_space.
417 _g1 = G1CollectedHeap::heap();
418
419 assert(Heap_lock->owned_by_self(), "Locking discipline.");
420
421 initialize_gc_policy_counters();
422
423 if (adaptive_young_list_length()) {
424 _young_list_fixed_length = 0;
425 } else {
426 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
427 }
428 _free_regions_at_end_of_collection = _g1->num_free_regions();
429
430 update_young_list_max_and_target_length();
431 // We may immediately start allocating regions and placing them on the
432 // collection set list. Initialize the per-collection set info
433 start_incremental_cset_building();
434 }
435
436 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
437 phase_times()->note_gc_start(num_active_workers);
438 }
439
440 // Create the jstat counters for the policy.
441 void G1CollectorPolicy::initialize_gc_policy_counters() {
442 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
443 }
444
445 bool G1CollectorPolicy::predict_will_fit(uint young_length,
446 double base_time_ms,
447 uint base_free_regions,
448 double target_pause_time_ms) const {
449 if (young_length >= base_free_regions) {
450 // end condition 1: not enough space for the young regions
451 return false;
452 }
453
454 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
455 size_t bytes_to_copy =
456 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
457 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
458 double young_other_time_ms = predict_young_other_time_ms(young_length);
459 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
460 if (pause_time_ms > target_pause_time_ms) {
461 // end condition 2: prediction is over the target pause time
462 return false;
463 }
464
465 size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
466
467 // When copying, we will likely need more bytes free than is live in the region.
468 // Add some safety margin to factor in the confidence of our guess, and the
469 // natural expected waste.
470 // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
471 // of the calculation: the lower the confidence, the more headroom.
472 // (100 + TargetPLABWastePct) represents the increase in expected bytes during
473 // copying due to anticipated waste in the PLABs.
474 double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
475 size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
476
477 if (expected_bytes_to_copy > free_bytes) {
478 // end condition 3: out-of-space
479 return false;
480 }
481
482 // success!
483 return true;
484 }
485
486 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
487 // re-calculate the necessary reserve
488 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
489 // We use ceiling so that if reserve_regions_d is > 0.0 (but
490 // smaller than 1.0) we'll get 1.
491 _reserve_regions = (uint) ceil(reserve_regions_d);
492
493 _young_gen_sizer->heap_size_changed(new_number_of_regions);
494 }
495
496 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
497 uint base_min_length) const {
498 uint desired_min_length = 0;
499 if (adaptive_young_list_length()) {
500 if (_alloc_rate_ms_seq->num() > 3) {
501 double now_sec = os::elapsedTime();
502 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
503 double alloc_rate_ms = predict_alloc_rate_ms();
504 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
505 } else {
506 // otherwise we don't have enough info to make the prediction
507 }
508 }
509 desired_min_length += base_min_length;
510 // make sure we don't go below any user-defined minimum bound
511 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
512 }
513
514 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
515 // Here, we might want to also take into account any additional
516 // constraints (i.e., user-defined minimum bound). Currently, we
517 // effectively don't set this bound.
518 return _young_gen_sizer->max_desired_young_length();
519 }
520
521 uint G1CollectorPolicy::update_young_list_max_and_target_length() {
522 return update_young_list_max_and_target_length(get_new_size_prediction(_rs_lengths_seq));
523 }
524
525 uint G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
526 uint unbounded_target_length = update_young_list_target_length(rs_lengths);
527 update_max_gc_locker_expansion();
528 return unbounded_target_length;
529 }
530
531 uint G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
532 YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
533 _young_list_target_length = young_lengths.first;
534 return young_lengths.second;
535 }
536
537 G1CollectorPolicy::YoungTargetLengths G1CollectorPolicy::young_list_target_lengths(size_t rs_lengths) const {
538 YoungTargetLengths result;
539
540 // Calculate the absolute and desired min bounds first.
541
542 // This is how many young regions we already have (currently: the survivors).
543 uint base_min_length = recorded_survivor_regions();
544 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
545 // This is the absolute minimum young length. Ensure that we
546 // will at least have one eden region available for allocation.
547 uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
548 // If we shrank the young list target it should not shrink below the current size.
549 desired_min_length = MAX2(desired_min_length, absolute_min_length);
550 // Calculate the absolute and desired max bounds.
551
552 uint desired_max_length = calculate_young_list_desired_max_length();
553
554 uint young_list_target_length = 0;
555 if (adaptive_young_list_length()) {
556 if (collector_state()->gcs_are_young()) {
557 young_list_target_length =
558 calculate_young_list_target_length(rs_lengths,
559 base_min_length,
560 desired_min_length,
561 desired_max_length);
562 } else {
563 // Don't calculate anything and let the code below bound it to
564 // the desired_min_length, i.e., do the next GC as soon as
565 // possible to maximize how many old regions we can add to it.
566 }
567 } else {
568 // The user asked for a fixed young gen so we'll fix the young gen
569 // whether the next GC is young or mixed.
570 young_list_target_length = _young_list_fixed_length;
571 }
572
573 result.second = young_list_target_length;
574
575 // We will try our best not to "eat" into the reserve.
576 uint absolute_max_length = 0;
577 if (_free_regions_at_end_of_collection > _reserve_regions) {
578 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
579 }
580 if (desired_max_length > absolute_max_length) {
581 desired_max_length = absolute_max_length;
582 }
583
584 // Make sure we don't go over the desired max length, nor under the
585 // desired min length. In case they clash, desired_min_length wins
586 // which is why that test is second.
587 if (young_list_target_length > desired_max_length) {
588 young_list_target_length = desired_max_length;
589 }
590 if (young_list_target_length < desired_min_length) {
591 young_list_target_length = desired_min_length;
592 }
593
594 assert(young_list_target_length > recorded_survivor_regions(),
595 "we should be able to allocate at least one eden region");
596 assert(young_list_target_length >= absolute_min_length, "post-condition");
597
598 result.first = young_list_target_length;
599 return result;
600 }
601
602 uint
603 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
604 uint base_min_length,
605 uint desired_min_length,
606 uint desired_max_length) const {
607 assert(adaptive_young_list_length(), "pre-condition");
608 assert(collector_state()->gcs_are_young(), "only call this for young GCs");
609
610 // In case some edge-condition makes the desired max length too small...
611 if (desired_max_length <= desired_min_length) {
612 return desired_min_length;
613 }
614
615 // We'll adjust min_young_length and max_young_length not to include
616 // the already allocated young regions (i.e., so they reflect the
617 // min and max eden regions we'll allocate). The base_min_length
618 // will be reflected in the predictions by the
619 // survivor_regions_evac_time prediction.
620 assert(desired_min_length > base_min_length, "invariant");
621 uint min_young_length = desired_min_length - base_min_length;
622 assert(desired_max_length > base_min_length, "invariant");
623 uint max_young_length = desired_max_length - base_min_length;
624
625 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
626 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
627 size_t pending_cards = get_new_size_prediction(_pending_cards_seq);
628 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
629 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
630 double base_time_ms =
631 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
632 survivor_regions_evac_time;
633 uint available_free_regions = _free_regions_at_end_of_collection;
634 uint base_free_regions = 0;
635 if (available_free_regions > _reserve_regions) {
636 base_free_regions = available_free_regions - _reserve_regions;
637 }
638
639 // Here, we will make sure that the shortest young length that
640 // makes sense fits within the target pause time.
641
642 if (predict_will_fit(min_young_length, base_time_ms,
643 base_free_regions, target_pause_time_ms)) {
644 // The shortest young length will fit into the target pause time;
645 // we'll now check whether the absolute maximum number of young
646 // regions will fit in the target pause time. If not, we'll do
647 // a binary search between min_young_length and max_young_length.
648 if (predict_will_fit(max_young_length, base_time_ms,
649 base_free_regions, target_pause_time_ms)) {
650 // The maximum young length will fit into the target pause time.
651 // We are done so set min young length to the maximum length (as
652 // the result is assumed to be returned in min_young_length).
653 min_young_length = max_young_length;
654 } else {
655 // The maximum possible number of young regions will not fit within
656 // the target pause time so we'll search for the optimal
657 // length. The loop invariants are:
658 //
659 // min_young_length < max_young_length
660 // min_young_length is known to fit into the target pause time
661 // max_young_length is known not to fit into the target pause time
662 //
663 // Going into the loop we know the above hold as we've just
664 // checked them. Every time around the loop we check whether
665 // the middle value between min_young_length and
666 // max_young_length fits into the target pause time. If it
667 // does, it becomes the new min. If it doesn't, it becomes
668 // the new max. This way we maintain the loop invariants.
669
670 assert(min_young_length < max_young_length, "invariant");
671 uint diff = (max_young_length - min_young_length) / 2;
672 while (diff > 0) {
673 uint young_length = min_young_length + diff;
674 if (predict_will_fit(young_length, base_time_ms,
675 base_free_regions, target_pause_time_ms)) {
676 min_young_length = young_length;
677 } else {
678 max_young_length = young_length;
679 }
680 assert(min_young_length < max_young_length, "invariant");
681 diff = (max_young_length - min_young_length) / 2;
682 }
683 // The results is min_young_length which, according to the
684 // loop invariants, should fit within the target pause time.
685
686 // These are the post-conditions of the binary search above:
687 assert(min_young_length < max_young_length,
688 "otherwise we should have discovered that max_young_length "
689 "fits into the pause target and not done the binary search");
690 assert(predict_will_fit(min_young_length, base_time_ms,
691 base_free_regions, target_pause_time_ms),
692 "min_young_length, the result of the binary search, should "
693 "fit into the pause target");
694 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
695 base_free_regions, target_pause_time_ms),
696 "min_young_length, the result of the binary search, should be "
697 "optimal, so no larger length should fit into the pause target");
698 }
699 } else {
700 // Even the minimum length doesn't fit into the pause time
701 // target, return it as the result nevertheless.
702 }
703 return base_min_length + min_young_length;
704 }
705
706 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
707 double survivor_regions_evac_time = 0.0;
708 for (HeapRegion * r = _recorded_survivor_head;
709 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
710 r = r->get_next_young_region()) {
711 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
712 }
713 return survivor_regions_evac_time;
714 }
715
716 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
717 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
718
719 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
720 if (rs_lengths > _rs_lengths_prediction) {
721 // add 10% to avoid having to recalculate often
722 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
723 update_rs_lengths_prediction(rs_lengths_prediction);
724
725 update_young_list_max_and_target_length(rs_lengths_prediction);
726 }
727 }
728
729 void G1CollectorPolicy::update_rs_lengths_prediction() {
730 update_rs_lengths_prediction(get_new_size_prediction(_rs_lengths_seq));
731 }
732
733 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
734 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
735 _rs_lengths_prediction = prediction;
736 }
737 }
738
739 #ifndef PRODUCT
740 bool G1CollectorPolicy::verify_young_ages() {
741 HeapRegion* head = _g1->young_list()->first_region();
742 return
743 verify_young_ages(head, _short_lived_surv_rate_group);
744 // also call verify_young_ages on any additional surv rate groups
745 }
746
747 bool
748 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
749 SurvRateGroup *surv_rate_group) {
750 guarantee( surv_rate_group != NULL, "pre-condition" );
751
752 const char* name = surv_rate_group->name();
753 bool ret = true;
754 int prev_age = -1;
755
756 for (HeapRegion* curr = head;
757 curr != NULL;
758 curr = curr->get_next_young_region()) {
759 SurvRateGroup* group = curr->surv_rate_group();
760 if (group == NULL && !curr->is_survivor()) {
761 log_error(gc, verify)("## %s: encountered NULL surv_rate_group", name);
762 ret = false;
763 }
764
765 if (surv_rate_group == group) {
766 int age = curr->age_in_surv_rate_group();
767
768 if (age < 0) {
769 log_error(gc, verify)("## %s: encountered negative age", name);
770 ret = false;
771 }
772
773 if (age <= prev_age) {
774 log_error(gc, verify)("## %s: region ages are not strictly increasing (%d, %d)", name, age, prev_age);
775 ret = false;
776 }
777 prev_age = age;
778 }
779 }
780
781 return ret;
782 }
783 #endif // PRODUCT
784
785 void G1CollectorPolicy::record_full_collection_start() {
786 _full_collection_start_sec = os::elapsedTime();
787 // Release the future to-space so that it is available for compaction into.
788 collector_state()->set_full_collection(true);
789 }
790
791 void G1CollectorPolicy::record_full_collection_end() {
792 // Consider this like a collection pause for the purposes of allocation
793 // since last pause.
794 double end_sec = os::elapsedTime();
795 double full_gc_time_sec = end_sec - _full_collection_start_sec;
796 double full_gc_time_ms = full_gc_time_sec * 1000.0;
797
798 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
799
800 update_recent_gc_times(end_sec, full_gc_time_ms);
801
802 collector_state()->set_full_collection(false);
803
804 // "Nuke" the heuristics that control the young/mixed GC
805 // transitions and make sure we start with young GCs after the Full GC.
806 collector_state()->set_gcs_are_young(true);
807 collector_state()->set_last_young_gc(false);
808 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
809 collector_state()->set_during_initial_mark_pause(false);
810 collector_state()->set_in_marking_window(false);
811 collector_state()->set_in_marking_window_im(false);
812
813 _short_lived_surv_rate_group->start_adding_regions();
814 // also call this on any additional surv rate groups
815
816 record_survivor_regions(0, NULL, NULL);
817
818 _free_regions_at_end_of_collection = _g1->num_free_regions();
819 // Reset survivors SurvRateGroup.
820 _survivor_surv_rate_group->reset();
821 update_young_list_max_and_target_length();
822 update_rs_lengths_prediction();
823 cset_chooser()->clear();
824
825 _bytes_allocated_in_old_since_last_gc = 0;
826
827 record_pause(FullGC, _full_collection_start_sec, end_sec);
828 }
829
830 void G1CollectorPolicy::record_stop_world_start() {
831 _stop_world_start = os::elapsedTime();
832 }
833
834 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
835 // We only need to do this here as the policy will only be applied
836 // to the GC we're about to start. so, no point is calculating this
837 // every time we calculate / recalculate the target young length.
838 update_survivors_policy();
839
840 assert(_g1->used() == _g1->recalculate_used(),
841 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
842 _g1->used(), _g1->recalculate_used());
843
844 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
845 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
846 _stop_world_start = 0.0;
847
848 phase_times()->record_cur_collection_start_sec(start_time_sec);
849 _pending_cards = _g1->pending_card_num();
850
851 _collection_set_bytes_used_before = 0;
852 _bytes_copied_during_gc = 0;
853
854 collector_state()->set_last_gc_was_young(false);
855
856 // do that for any other surv rate groups
857 _short_lived_surv_rate_group->stop_adding_regions();
858 _survivors_age_table.clear();
859
860 assert( verify_young_ages(), "region age verification" );
861 }
862
863 void G1CollectorPolicy::record_concurrent_mark_init_end(double
864 mark_init_elapsed_time_ms) {
865 collector_state()->set_during_marking(true);
866 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
867 collector_state()->set_during_initial_mark_pause(false);
868 }
869
870 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
871 _mark_remark_start_sec = os::elapsedTime();
872 collector_state()->set_during_marking(false);
873 }
874
875 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
876 double end_time_sec = os::elapsedTime();
877 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
878 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
879 _prev_collection_pause_end_ms += elapsed_time_ms;
880
881 record_pause(Remark, _mark_remark_start_sec, end_time_sec);
882 }
883
884 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
885 _mark_cleanup_start_sec = os::elapsedTime();
886 }
887
888 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
889 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
890 "skip last young-only gc");
891 collector_state()->set_last_young_gc(should_continue_with_reclaim);
892 // We skip the marking phase.
893 if (!should_continue_with_reclaim) {
894 abort_time_to_mixed_tracking();
895 }
896 collector_state()->set_in_marking_window(false);
897 }
898
899 void G1CollectorPolicy::record_concurrent_pause() {
900 if (_stop_world_start > 0.0) {
901 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
902 _trace_young_gen_time_data.record_yield_time(yield_ms);
903 }
904 }
905
906 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
907 return phase_times()->average_time_ms(phase);
908 }
909
910 double G1CollectorPolicy::young_other_time_ms() const {
911 return phase_times()->young_cset_choice_time_ms() +
912 phase_times()->young_free_cset_time_ms();
913 }
914
915 double G1CollectorPolicy::non_young_other_time_ms() const {
916 return phase_times()->non_young_cset_choice_time_ms() +
917 phase_times()->non_young_free_cset_time_ms();
918
919 }
920
921 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
922 return pause_time_ms -
923 average_time_ms(G1GCPhaseTimes::UpdateRS) -
924 average_time_ms(G1GCPhaseTimes::ScanRS) -
925 average_time_ms(G1GCPhaseTimes::ObjCopy) -
926 average_time_ms(G1GCPhaseTimes::Termination);
927 }
928
929 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
930 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
931 }
932
933 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
934 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
935 }
936
937 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
938 if (about_to_start_mixed_phase()) {
939 return false;
940 }
941
942 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
943
944 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
945 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
946 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
947
948 bool result = false;
949 if (marking_request_bytes > marking_initiating_used_threshold) {
950 result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
951 log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
952 result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
953 cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
954 }
955
956 return result;
957 }
958
959 // Anything below that is considered to be zero
960 #define MIN_TIMER_GRANULARITY 0.0000001
961
962 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
963 double end_time_sec = os::elapsedTime();
964
965 size_t cur_used_bytes = _g1->used();
966 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
967 bool last_pause_included_initial_mark = false;
968 bool update_stats = !_g1->evacuation_failed();
969
970 NOT_PRODUCT(_short_lived_surv_rate_group->print());
971
972 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
973
974 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
975 if (last_pause_included_initial_mark) {
976 record_concurrent_mark_init_end(0.0);
977 } else {
978 maybe_start_marking();
979 }
980
981 double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
982 if (app_time_ms < MIN_TIMER_GRANULARITY) {
983 // This usually happens due to the timer not having the required
984 // granularity. Some Linuxes are the usual culprits.
985 // We'll just set it to something (arbitrarily) small.
986 app_time_ms = 1.0;
987 }
988
989 if (update_stats) {
990 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
991 // We maintain the invariant that all objects allocated by mutator
992 // threads will be allocated out of eden regions. So, we can use
993 // the eden region number allocated since the previous GC to
994 // calculate the application's allocate rate. The only exception
995 // to that is humongous objects that are allocated separately. But
996 // given that humongous object allocations do not really affect
997 // either the pause's duration nor when the next pause will take
998 // place we can safely ignore them here.
999 uint regions_allocated = eden_cset_region_length();
1000 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1001 _alloc_rate_ms_seq->add(alloc_rate_ms);
1002
1003 double interval_ms =
1004 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1005 update_recent_gc_times(end_time_sec, pause_time_ms);
1006 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1007 if (recent_avg_pause_time_ratio() < 0.0 ||
1008 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1009 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1010 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1011 if (_recent_avg_pause_time_ratio < 0.0) {
1012 _recent_avg_pause_time_ratio = 0.0;
1013 } else {
1014 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1015 _recent_avg_pause_time_ratio = 1.0;
1016 }
1017 }
1018
1019 // Compute the ratio of just this last pause time to the entire time range stored
1020 // in the vectors. Comparing this pause to the entire range, rather than only the
1021 // most recent interval, has the effect of smoothing over a possible transient 'burst'
1022 // of more frequent pauses that don't really reflect a change in heap occupancy.
1023 // This reduces the likelihood of a needless heap expansion being triggered.
1024 _last_pause_time_ratio =
1025 (pause_time_ms * _recent_prev_end_times_for_all_gcs_sec->num()) / interval_ms;
1026 }
1027
1028 bool new_in_marking_window = collector_state()->in_marking_window();
1029 bool new_in_marking_window_im = false;
1030 if (last_pause_included_initial_mark) {
1031 new_in_marking_window = true;
1032 new_in_marking_window_im = true;
1033 }
1034
1035 if (collector_state()->last_young_gc()) {
1036 // This is supposed to to be the "last young GC" before we start
1037 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1038 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1039
1040 if (next_gc_should_be_mixed("start mixed GCs",
1041 "do not start mixed GCs")) {
1042 collector_state()->set_gcs_are_young(false);
1043 } else {
1044 // We aborted the mixed GC phase early.
1045 abort_time_to_mixed_tracking();
1046 }
1047
1048 collector_state()->set_last_young_gc(false);
1049 }
1050
1051 if (!collector_state()->last_gc_was_young()) {
1052 // This is a mixed GC. Here we decide whether to continue doing
1053 // mixed GCs or not.
1054 if (!next_gc_should_be_mixed("continue mixed GCs",
1055 "do not continue mixed GCs")) {
1056 collector_state()->set_gcs_are_young(true);
1057
1058 maybe_start_marking();
1059 }
1060 }
1061
1062 _short_lived_surv_rate_group->start_adding_regions();
1063 // Do that for any other surv rate groups
1064
1065 double scan_hcc_time_ms = ConcurrentG1Refine::hot_card_cache_enabled() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;
1066
1067 if (update_stats) {
1068 double cost_per_card_ms = 0.0;
1069 if (_pending_cards > 0) {
1070 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;
1071 _cost_per_card_ms_seq->add(cost_per_card_ms);
1072 }
1073 _cost_scan_hcc_seq->add(scan_hcc_time_ms);
1074
1075 double cost_per_entry_ms = 0.0;
1076 if (cards_scanned > 10) {
1077 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1078 if (collector_state()->last_gc_was_young()) {
1079 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1080 } else {
1081 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1082 }
1083 }
1084
1085 if (_max_rs_lengths > 0) {
1086 double cards_per_entry_ratio =
1087 (double) cards_scanned / (double) _max_rs_lengths;
1088 if (collector_state()->last_gc_was_young()) {
1089 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1090 } else {
1091 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1092 }
1093 }
1094
1095 // This is defensive. For a while _max_rs_lengths could get
1096 // smaller than _recorded_rs_lengths which was causing
1097 // rs_length_diff to get very large and mess up the RSet length
1098 // predictions. The reason was unsafe concurrent updates to the
1099 // _inc_cset_recorded_rs_lengths field which the code below guards
1100 // against (see CR 7118202). This bug has now been fixed (see CR
1101 // 7119027). However, I'm still worried that
1102 // _inc_cset_recorded_rs_lengths might still end up somewhat
1103 // inaccurate. The concurrent refinement thread calculates an
1104 // RSet's length concurrently with other CR threads updating it
1105 // which might cause it to calculate the length incorrectly (if,
1106 // say, it's in mid-coarsening). So I'll leave in the defensive
1107 // conditional below just in case.
1108 size_t rs_length_diff = 0;
1109 if (_max_rs_lengths > _recorded_rs_lengths) {
1110 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1111 }
1112 _rs_length_diff_seq->add((double) rs_length_diff);
1113
1114 size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
1115 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1116 double cost_per_byte_ms = 0.0;
1117
1118 if (copied_bytes > 0) {
1119 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1120 if (collector_state()->in_marking_window()) {
1121 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1122 } else {
1123 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1124 }
1125 }
1126
1127 if (young_cset_region_length() > 0) {
1128 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1129 young_cset_region_length());
1130 }
1131
1132 if (old_cset_region_length() > 0) {
1133 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1134 old_cset_region_length());
1135 }
1136
1137 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1138
1139 _pending_cards_seq->add((double) _pending_cards);
1140 _rs_lengths_seq->add((double) _max_rs_lengths);
1141 }
1142
1143 collector_state()->set_in_marking_window(new_in_marking_window);
1144 collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1145 _free_regions_at_end_of_collection = _g1->num_free_regions();
1146 // IHOP control wants to know the expected young gen length if it were not
1147 // restrained by the heap reserve. Using the actual length would make the
1148 // prediction too small and the limit the young gen every time we get to the
1149 // predicted target occupancy.
1150 size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
1151 update_rs_lengths_prediction();
1152
1153 update_ihop_prediction(app_time_ms / 1000.0,
1154 _bytes_allocated_in_old_since_last_gc,
1155 last_unrestrained_young_length * HeapRegion::GrainBytes);
1156 _bytes_allocated_in_old_since_last_gc = 0;
1157
1158 _ihop_control->send_trace_event(_g1->gc_tracer_stw());
1159
1160 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1161 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1162
1163 if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1164 log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
1165 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
1166 update_rs_time_goal_ms, scan_hcc_time_ms);
1167
1168 update_rs_time_goal_ms = 0;
1169 } else {
1170 update_rs_time_goal_ms -= scan_hcc_time_ms;
1171 }
1172 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1173 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1174 update_rs_time_goal_ms);
1175
1176 cset_chooser()->verify();
1177 }
1178
1179 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1180 if (G1UseAdaptiveIHOP) {
1181 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1182 G1CollectedHeap::heap()->max_capacity(),
1183 &_predictor,
1184 G1ReservePercent,
1185 G1HeapWastePercent);
1186 } else {
1187 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1188 G1CollectedHeap::heap()->max_capacity());
1189 }
1190 }
1191
1192 void G1CollectorPolicy::update_ihop_prediction(double mutator_time_s,
1193 size_t mutator_alloc_bytes,
1194 size_t young_gen_size) {
1195 // Always try to update IHOP prediction. Even evacuation failures give information
1196 // about e.g. whether to start IHOP earlier next time.
1197
1198 // Avoid using really small application times that might create samples with
1199 // very high or very low values. They may be caused by e.g. back-to-back gcs.
1200 double const min_valid_time = 1e-6;
1201
1202 bool report = false;
1203
1204 double marking_to_mixed_time = -1.0;
1205 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1206 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1207 assert(marking_to_mixed_time > 0.0,
1208 "Initial mark to mixed time must be larger than zero but is %.3f",
1209 marking_to_mixed_time);
1210 if (marking_to_mixed_time > min_valid_time) {
1211 _ihop_control->update_marking_length(marking_to_mixed_time);
1212 report = true;
1213 }
1214 }
1215
1216 // As an approximation for the young gc promotion rates during marking we use
1217 // all of them. In many applications there are only a few if any young gcs during
1218 // marking, which makes any prediction useless. This increases the accuracy of the
1219 // prediction.
1220 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1221 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1222 report = true;
1223 }
1224
1225 if (report) {
1226 report_ihop_statistics();
1227 }
1228 }
1229
1230 void G1CollectorPolicy::report_ihop_statistics() {
1231 _ihop_control->print();
1232 }
1233
1234 void G1CollectorPolicy::print_phases() {
1235 phase_times()->print();
1236 }
1237
1238 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1239 double update_rs_processed_buffers,
1240 double goal_ms) {
1241 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1242 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1243
1244 if (G1UseAdaptiveConcRefinement) {
1245 const int k_gy = 3, k_gr = 6;
1246 const double inc_k = 1.1, dec_k = 0.9;
1247
1248 int g = cg1r->green_zone();
1249 if (update_rs_time > goal_ms) {
1250 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1251 } else {
1252 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1253 g = (int)MAX2(g * inc_k, g + 1.0);
1254 }
1255 }
1256 // Change the refinement threads params
1257 cg1r->set_green_zone(g);
1258 cg1r->set_yellow_zone(g * k_gy);
1259 cg1r->set_red_zone(g * k_gr);
1260 cg1r->reinitialize_threads();
1261
1262 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1263 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1264 cg1r->yellow_zone());
1265 // Change the barrier params
1266 dcqs.set_process_completed_threshold(processing_threshold);
1267 dcqs.set_max_completed_queue(cg1r->red_zone());
1268 }
1269
1270 int curr_queue_size = dcqs.completed_buffers_num();
1271 if (curr_queue_size >= cg1r->yellow_zone()) {
1272 dcqs.set_completed_queue_padding(curr_queue_size);
1273 } else {
1274 dcqs.set_completed_queue_padding(0);
1275 }
1276 dcqs.notify_if_necessary();
1277 }
1278
1279 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1280 return get_new_size_prediction(_rs_length_diff_seq);
1281 }
1282
1283 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1284 return get_new_prediction(_alloc_rate_ms_seq);
1285 }
1286
1287 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1288 return get_new_prediction(_cost_per_card_ms_seq);
1289 }
1290
1291 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1292 return get_new_prediction(_cost_scan_hcc_seq);
1293 }
1294
1295 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1296 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1297 }
1298
1299 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1300 return get_new_prediction(_young_cards_per_entry_ratio_seq);
1301 }
1302
1303 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1304 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1305 return predict_young_cards_per_entry_ratio();
1306 } else {
1307 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1308 }
1309 }
1310
1311 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1312 return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1313 }
1314
1315 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1316 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1317 }
1318
1319 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1320 if (collector_state()->gcs_are_young()) {
1321 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1322 } else {
1323 return predict_mixed_rs_scan_time_ms(card_num);
1324 }
1325 }
1326
1327 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1328 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1329 return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1330 } else {
1331 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1332 }
1333 }
1334
1335 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1336 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1337 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1338 } else {
1339 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1340 }
1341 }
1342
1343 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1344 if (collector_state()->during_concurrent_mark()) {
1345 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1346 } else {
1347 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1348 }
1349 }
1350
1351 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1352 return get_new_prediction(_constant_other_time_ms_seq);
1353 }
1354
1355 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1356 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1357 }
1358
1359 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1360 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1361 }
1362
1363 double G1CollectorPolicy::predict_remark_time_ms() const {
1364 return get_new_prediction(_concurrent_mark_remark_times_ms);
1365 }
1366
1367 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1368 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1369 }
1370
1371 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1372 TruncatedSeq* seq = surv_rate_group->get_seq(age);
1373 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1374 double pred = get_new_prediction(seq);
1375 if (pred > 1.0) {
1376 pred = 1.0;
1377 }
1378 return pred;
1379 }
1380
1381 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1382 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1383 }
1384
1385 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1386 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1387 }
1388
1389 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1390 size_t scanned_cards) const {
1391 return
1392 predict_rs_update_time_ms(pending_cards) +
1393 predict_rs_scan_time_ms(scanned_cards) +
1394 predict_constant_other_time_ms();
1395 }
1396
1397 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1398 size_t rs_length = predict_rs_length_diff();
1399 size_t card_num;
1400 if (collector_state()->gcs_are_young()) {
1401 card_num = predict_young_card_num(rs_length);
1402 } else {
1403 card_num = predict_non_young_card_num(rs_length);
1404 }
1405 return predict_base_elapsed_time_ms(pending_cards, card_num);
1406 }
1407
1408 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1409 size_t bytes_to_copy;
1410 if (hr->is_marked())
1411 bytes_to_copy = hr->max_live_bytes();
1412 else {
1413 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1414 int age = hr->age_in_surv_rate_group();
1415 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1416 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1417 }
1418 return bytes_to_copy;
1419 }
1420
1421 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1422 bool for_young_gc) const {
1423 size_t rs_length = hr->rem_set()->occupied();
1424 size_t card_num;
1425
1426 // Predicting the number of cards is based on which type of GC
1427 // we're predicting for.
1428 if (for_young_gc) {
1429 card_num = predict_young_card_num(rs_length);
1430 } else {
1431 card_num = predict_non_young_card_num(rs_length);
1432 }
1433 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1434
1435 double region_elapsed_time_ms =
1436 predict_rs_scan_time_ms(card_num) +
1437 predict_object_copy_time_ms(bytes_to_copy);
1438
1439 // The prediction of the "other" time for this region is based
1440 // upon the region type and NOT the GC type.
1441 if (hr->is_young()) {
1442 region_elapsed_time_ms += predict_young_other_time_ms(1);
1443 } else {
1444 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1445 }
1446 return region_elapsed_time_ms;
1447 }
1448
1449 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1450 uint survivor_cset_region_length) {
1451 _eden_cset_region_length = eden_cset_region_length;
1452 _survivor_cset_region_length = survivor_cset_region_length;
1453 _old_cset_region_length = 0;
1454 }
1455
1456 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1457 _recorded_rs_lengths = rs_lengths;
1458 }
1459
1460 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1461 double elapsed_ms) {
1462 _recent_gc_times_ms->add(elapsed_ms);
1463 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1464 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1465 }
1466
1467 void G1CollectorPolicy::clear_ratio_check_data() {
1468 _ratio_over_threshold_count = 0;
1469 _ratio_over_threshold_sum = 0.0;
1470 _pauses_since_start = 0;
1471 }
1472
1473 size_t G1CollectorPolicy::expansion_amount() {
1474 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1475 double last_gc_overhead = _last_pause_time_ratio * 100.0;
1476 double threshold = _gc_overhead_perc;
1477 size_t expand_bytes = 0;
1478
1479 // If the heap is at less than half its maximum size, scale the threshold down,
1480 // to a limit of 1. Thus the smaller the heap is, the more likely it is to expand,
1481 // though the scaling code will likely keep the increase small.
1482 if (_g1->capacity() <= _g1->max_capacity() / 2) {
1483 threshold *= (double)_g1->capacity() / (double)(_g1->max_capacity() / 2);
1484 threshold = MAX2(threshold, 1.0);
1485 }
1486
1487 // If the last GC time ratio is over the threshold, increment the count of
1488 // times it has been exceeded, and add this ratio to the sum of exceeded
1489 // ratios.
1490 if (last_gc_overhead > threshold) {
1491 _ratio_over_threshold_count++;
1492 _ratio_over_threshold_sum += last_gc_overhead;
1493 }
1494
1495 // Check if we've had enough GC time ratio checks that were over the
1496 // threshold to trigger an expansion. We'll also expand if we've
1497 // reached the end of the history buffer and the average of all entries
1498 // is still over the threshold. This indicates a smaller number of GCs were
1499 // long enough to make the average exceed the threshold.
1500 bool filled_history_buffer = _pauses_since_start == NumPrevPausesForHeuristics;
1501 if ((_ratio_over_threshold_count == MinOverThresholdForGrowth) ||
1502 (filled_history_buffer && (recent_gc_overhead > threshold))) {
1503 size_t min_expand_bytes = HeapRegion::GrainBytes;
1504 size_t reserved_bytes = _g1->max_capacity();
1505 size_t committed_bytes = _g1->capacity();
1506 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1507 size_t expand_bytes_via_pct =
1508 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1509 double scale_factor = 1.0;
1510
1511 // If the current size is less than 1/4 of the Initial heap size, expand
1512 // by half of the delta between the current and Initial sizes. IE, grow
1513 // back quickly.
1514 //
1515 // Otherwise, take the current size, or G1ExpandByPercentOfAvailable % of
1516 // the available expansion space, whichever is smaller, as the base
1517 // expansion size. Then possibly scale this size according to how much the
1518 // threshold has (on average) been exceeded by. If the delta is small
1519 // (less than the StartScaleDownAt value), scale the size down linearly, but
1520 // not by less than MinScaleDownFactor. If the delta is large (greater than
1521 // the StartScaleUpAt value), scale up, but adding no more than MaxScaleUpFactor
1522 // times the base size. The scaling will be linear in the range from
1523 // StartScaleUpAt to (StartScaleUpAt + ScaleUpRange). In other words,
1524 // ScaleUpRange sets the rate of scaling up.
1525 if (committed_bytes < InitialHeapSize / 4) {
1526 expand_bytes = (InitialHeapSize - committed_bytes) / 2;
1527 } else {
1528 double const MinScaleDownFactor = 0.2;
1529 double const MaxScaleUpFactor = 2;
1530 double const StartScaleDownAt = _gc_overhead_perc;
1531 double const StartScaleUpAt = _gc_overhead_perc * 1.5;
1532 double const ScaleUpRange = _gc_overhead_perc * 2.0;
1533
1534 double ratio_delta;
1535 if (filled_history_buffer) {
1536 ratio_delta = recent_gc_overhead - threshold;
1537 } else {
1538 ratio_delta = (_ratio_over_threshold_sum/_ratio_over_threshold_count) - threshold;
1539 }
1540
1541 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1542 if (ratio_delta < StartScaleDownAt) {
1543 scale_factor = ratio_delta / StartScaleDownAt;
1544 scale_factor = MAX2(scale_factor, MinScaleDownFactor);
1545 } else if (ratio_delta > StartScaleUpAt) {
1546 scale_factor = 1 + ((ratio_delta - StartScaleUpAt) / ScaleUpRange);
1547 scale_factor = MIN2(scale_factor, MaxScaleUpFactor);
1548 }
1549 }
1550
1551 log_debug(gc, ergo, heap)("Attempt heap expansion (recent GC overhead higher than threshold after GC) "
1552 "recent GC overhead: %1.2f %% threshold: %1.2f %% uncommitted: " SIZE_FORMAT "B base expansion amount and scale: " SIZE_FORMAT "B (%1.2f%%)",
1553 recent_gc_overhead, threshold, uncommitted_bytes, expand_bytes, scale_factor * 100);
1554
1555 expand_bytes = static_cast<size_t>(expand_bytes * scale_factor);
1556
1557 // Ensure the expansion size is at least the minimum growth amount
1558 // and at most the remaining uncommitted byte size.
1559 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1560 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1561
1562 clear_ratio_check_data();
1563 } else {
1564 // An expansion was not triggered. If we've started counting, increment
1565 // the number of checks we've made in the current window. If we've
1566 // reached the end of the window without resizing, clear the counters to
1567 // start again the next time we see a ratio above the threshold.
1568 if (_ratio_over_threshold_count > 0) {
1569 _pauses_since_start++;
1570 if (_pauses_since_start > NumPrevPausesForHeuristics) {
1571 clear_ratio_check_data();
1572 }
1573 }
1574 }
1575
1576 return expand_bytes;
1577 }
1578
1579 void G1CollectorPolicy::print_tracing_info() const {
1580 _trace_young_gen_time_data.print();
1581 _trace_old_gen_time_data.print();
1582 }
1583
1584 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1585 #ifndef PRODUCT
1586 _short_lived_surv_rate_group->print_surv_rate_summary();
1587 // add this call for any other surv rate groups
1588 #endif // PRODUCT
1589 }
1590
1591 bool G1CollectorPolicy::is_young_list_full() const {
1592 uint young_list_length = _g1->young_list()->length();
1593 uint young_list_target_length = _young_list_target_length;
1594 return young_list_length >= young_list_target_length;
1595 }
1596
1597 bool G1CollectorPolicy::can_expand_young_list() const {
1598 uint young_list_length = _g1->young_list()->length();
1599 uint young_list_max_length = _young_list_max_length;
1600 return young_list_length < young_list_max_length;
1601 }
1602
1603 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1604 uint expansion_region_num = 0;
1605 if (GCLockerEdenExpansionPercent > 0) {
1606 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1607 double expansion_region_num_d = perc * (double) _young_list_target_length;
1608 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1609 // less than 1.0) we'll get 1.
1610 expansion_region_num = (uint) ceil(expansion_region_num_d);
1611 } else {
1612 assert(expansion_region_num == 0, "sanity");
1613 }
1614 _young_list_max_length = _young_list_target_length + expansion_region_num;
1615 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1616 }
1617
1618 // Calculates survivor space parameters.
1619 void G1CollectorPolicy::update_survivors_policy() {
1620 double max_survivor_regions_d =
1621 (double) _young_list_target_length / (double) SurvivorRatio;
1622 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1623 // smaller than 1.0) we'll get 1.
1624 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1625
1626 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1627 HeapRegion::GrainWords * _max_survivor_regions, counters());
1628 }
1629
1630 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1631 // We actually check whether we are marking here and not if we are in a
1632 // reclamation phase. This means that we will schedule a concurrent mark
1633 // even while we are still in the process of reclaiming memory.
1634 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1635 if (!during_cycle) {
1636 log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
1637 collector_state()->set_initiate_conc_mark_if_possible(true);
1638 return true;
1639 } else {
1640 log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
1641 return false;
1642 }
1643 }
1644
1645 void G1CollectorPolicy::initiate_conc_mark() {
1646 collector_state()->set_during_initial_mark_pause(true);
1647 collector_state()->set_initiate_conc_mark_if_possible(false);
1648 }
1649
1650 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1651 // We are about to decide on whether this pause will be an
1652 // initial-mark pause.
1653
1654 // First, collector_state()->during_initial_mark_pause() should not be already set. We
1655 // will set it here if we have to. However, it should be cleared by
1656 // the end of the pause (it's only set for the duration of an
1657 // initial-mark pause).
1658 assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1659
1660 if (collector_state()->initiate_conc_mark_if_possible()) {
1661 // We had noticed on a previous pause that the heap occupancy has
1662 // gone over the initiating threshold and we should start a
1663 // concurrent marking cycle. So we might initiate one.
1664
1665 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1666 // Initiate a new initial mark if there is no marking or reclamation going on.
1667 initiate_conc_mark();
1668 log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
1669 } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
1670 // Initiate a user requested initial mark. An initial mark must be young only
1671 // GC, so the collector state must be updated to reflect this.
1672 collector_state()->set_gcs_are_young(true);
1673 collector_state()->set_last_young_gc(false);
1674
1675 abort_time_to_mixed_tracking();
1676 initiate_conc_mark();
1677 log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
1678 } else {
1679 // The concurrent marking thread is still finishing up the
1680 // previous cycle. If we start one right now the two cycles
1681 // overlap. In particular, the concurrent marking thread might
1682 // be in the process of clearing the next marking bitmap (which
1683 // we will use for the next cycle if we start one). Starting a
1684 // cycle now will be bad given that parts of the marking
1685 // information might get cleared by the marking thread. And we
1686 // cannot wait for the marking thread to finish the cycle as it
1687 // periodically yields while clearing the next marking bitmap
1688 // and, if it's in a yield point, it's waiting for us to
1689 // finish. So, at this point we will not start a cycle and we'll
1690 // let the concurrent marking thread complete the last one.
1691 log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
1692 }
1693 }
1694 }
1695
1696 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1697 G1CollectedHeap* _g1h;
1698 CSetChooserParUpdater _cset_updater;
1699
1700 public:
1701 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1702 uint chunk_size) :
1703 _g1h(G1CollectedHeap::heap()),
1704 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1705
1706 bool doHeapRegion(HeapRegion* r) {
1707 // Do we have any marking information for this region?
1708 if (r->is_marked()) {
1709 // We will skip any region that's currently used as an old GC
1710 // alloc region (we should not consider those for collection
1711 // before we fill them up).
1712 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1713 _cset_updater.add_region(r);
1714 }
1715 }
1716 return false;
1717 }
1718 };
1719
1720 class ParKnownGarbageTask: public AbstractGangTask {
1721 CollectionSetChooser* _hrSorted;
1722 uint _chunk_size;
1723 G1CollectedHeap* _g1;
1724 HeapRegionClaimer _hrclaimer;
1725
1726 public:
1727 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1728 AbstractGangTask("ParKnownGarbageTask"),
1729 _hrSorted(hrSorted), _chunk_size(chunk_size),
1730 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1731
1732 void work(uint worker_id) {
1733 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1734 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1735 }
1736 };
1737
1738 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1739 assert(n_workers > 0, "Active gc workers should be greater than 0");
1740 const uint overpartition_factor = 4;
1741 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1742 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1743 }
1744
1745 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1746 cset_chooser()->clear();
1747
1748 WorkGang* workers = _g1->workers();
1749 uint n_workers = workers->active_workers();
1750
1751 uint n_regions = _g1->num_regions();
1752 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1753 cset_chooser()->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1754 ParKnownGarbageTask par_known_garbage_task(cset_chooser(), chunk_size, n_workers);
1755 workers->run_task(&par_known_garbage_task);
1756
1757 cset_chooser()->sort_regions();
1758
1759 double end_sec = os::elapsedTime();
1760 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1761 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1762 _prev_collection_pause_end_ms += elapsed_time_ms;
1763
1764 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1765 }
1766
1767 // Add the heap region at the head of the non-incremental collection set
1768 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1769 assert(_inc_cset_build_state == Active, "Precondition");
1770 assert(hr->is_old(), "the region should be old");
1771
1772 assert(!hr->in_collection_set(), "should not already be in the CSet");
1773 _g1->register_old_region_with_cset(hr);
1774 hr->set_next_in_collection_set(_collection_set);
1775 _collection_set = hr;
1776 _collection_set_bytes_used_before += hr->used();
1777 size_t rs_length = hr->rem_set()->occupied();
1778 _recorded_rs_lengths += rs_length;
1779 _old_cset_region_length += 1;
1780 }
1781
1782 // Initialize the per-collection-set information
1783 void G1CollectorPolicy::start_incremental_cset_building() {
1784 assert(_inc_cset_build_state == Inactive, "Precondition");
1785
1786 _inc_cset_head = NULL;
1787 _inc_cset_tail = NULL;
1788 _inc_cset_bytes_used_before = 0;
1789
1790 _inc_cset_max_finger = 0;
1791 _inc_cset_recorded_rs_lengths = 0;
1792 _inc_cset_recorded_rs_lengths_diffs = 0;
1793 _inc_cset_predicted_elapsed_time_ms = 0.0;
1794 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1795 _inc_cset_build_state = Active;
1796 }
1797
1798 void G1CollectorPolicy::finalize_incremental_cset_building() {
1799 assert(_inc_cset_build_state == Active, "Precondition");
1800 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1801
1802 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1803 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1804 // that adds a new region to the CSet. Further updates by the
1805 // concurrent refinement thread that samples the young RSet lengths
1806 // are accumulated in the *_diffs fields. Here we add the diffs to
1807 // the "main" fields.
1808
1809 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1810 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1811 } else {
1812 // This is defensive. The diff should in theory be always positive
1813 // as RSets can only grow between GCs. However, given that we
1814 // sample their size concurrently with other threads updating them
1815 // it's possible that we might get the wrong size back, which
1816 // could make the calculations somewhat inaccurate.
1817 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1818 if (_inc_cset_recorded_rs_lengths >= diffs) {
1819 _inc_cset_recorded_rs_lengths -= diffs;
1820 } else {
1821 _inc_cset_recorded_rs_lengths = 0;
1822 }
1823 }
1824 _inc_cset_predicted_elapsed_time_ms +=
1825 _inc_cset_predicted_elapsed_time_ms_diffs;
1826
1827 _inc_cset_recorded_rs_lengths_diffs = 0;
1828 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1829 }
1830
1831 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1832 // This routine is used when:
1833 // * adding survivor regions to the incremental cset at the end of an
1834 // evacuation pause,
1835 // * adding the current allocation region to the incremental cset
1836 // when it is retired, and
1837 // * updating existing policy information for a region in the
1838 // incremental cset via young list RSet sampling.
1839 // Therefore this routine may be called at a safepoint by the
1840 // VM thread, or in-between safepoints by mutator threads (when
1841 // retiring the current allocation region) or a concurrent
1842 // refine thread (RSet sampling).
1843
1844 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1845 size_t used_bytes = hr->used();
1846 _inc_cset_recorded_rs_lengths += rs_length;
1847 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1848 _inc_cset_bytes_used_before += used_bytes;
1849
1850 // Cache the values we have added to the aggregated information
1851 // in the heap region in case we have to remove this region from
1852 // the incremental collection set, or it is updated by the
1853 // rset sampling code
1854 hr->set_recorded_rs_length(rs_length);
1855 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1856 }
1857
1858 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1859 size_t new_rs_length) {
1860 // Update the CSet information that is dependent on the new RS length
1861 assert(hr->is_young(), "Precondition");
1862 assert(!SafepointSynchronize::is_at_safepoint(),
1863 "should not be at a safepoint");
1864
1865 // We could have updated _inc_cset_recorded_rs_lengths and
1866 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1867 // that atomically, as this code is executed by a concurrent
1868 // refinement thread, potentially concurrently with a mutator thread
1869 // allocating a new region and also updating the same fields. To
1870 // avoid the atomic operations we accumulate these updates on two
1871 // separate fields (*_diffs) and we'll just add them to the "main"
1872 // fields at the start of a GC.
1873
1874 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1875 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1876 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1877
1878 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1879 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1880 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1881 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1882
1883 hr->set_recorded_rs_length(new_rs_length);
1884 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1885 }
1886
1887 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1888 assert(hr->is_young(), "invariant");
1889 assert(hr->young_index_in_cset() > -1, "should have already been set");
1890 assert(_inc_cset_build_state == Active, "Precondition");
1891
1892 // We need to clear and set the cached recorded/cached collection set
1893 // information in the heap region here (before the region gets added
1894 // to the collection set). An individual heap region's cached values
1895 // are calculated, aggregated with the policy collection set info,
1896 // and cached in the heap region here (initially) and (subsequently)
1897 // by the Young List sampling code.
1898
1899 size_t rs_length = hr->rem_set()->occupied();
1900 add_to_incremental_cset_info(hr, rs_length);
1901
1902 HeapWord* hr_end = hr->end();
1903 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1904
1905 assert(!hr->in_collection_set(), "invariant");
1906 _g1->register_young_region_with_cset(hr);
1907 assert(hr->next_in_collection_set() == NULL, "invariant");
1908 }
1909
1910 // Add the region at the RHS of the incremental cset
1911 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1912 // We should only ever be appending survivors at the end of a pause
1913 assert(hr->is_survivor(), "Logic");
1914
1915 // Do the 'common' stuff
1916 add_region_to_incremental_cset_common(hr);
1917
1918 // Now add the region at the right hand side
1919 if (_inc_cset_tail == NULL) {
1920 assert(_inc_cset_head == NULL, "invariant");
1921 _inc_cset_head = hr;
1922 } else {
1923 _inc_cset_tail->set_next_in_collection_set(hr);
1924 }
1925 _inc_cset_tail = hr;
1926 }
1927
1928 // Add the region to the LHS of the incremental cset
1929 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1930 // Survivors should be added to the RHS at the end of a pause
1931 assert(hr->is_eden(), "Logic");
1932
1933 // Do the 'common' stuff
1934 add_region_to_incremental_cset_common(hr);
1935
1936 // Add the region at the left hand side
1937 hr->set_next_in_collection_set(_inc_cset_head);
1938 if (_inc_cset_head == NULL) {
1939 assert(_inc_cset_tail == NULL, "Invariant");
1940 _inc_cset_tail = hr;
1941 }
1942 _inc_cset_head = hr;
1943 }
1944
1945 #ifndef PRODUCT
1946 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1947 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1948
1949 st->print_cr("\nCollection_set:");
1950 HeapRegion* csr = list_head;
1951 while (csr != NULL) {
1952 HeapRegion* next = csr->next_in_collection_set();
1953 assert(csr->in_collection_set(), "bad CS");
1954 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
1955 HR_FORMAT_PARAMS(csr),
1956 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
1957 csr->age_in_surv_rate_group_cond());
1958 csr = next;
1959 }
1960 }
1961 #endif // !PRODUCT
1962
1963 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
1964 // Returns the given amount of reclaimable bytes (that represents
1965 // the amount of reclaimable space still to be collected) as a
1966 // percentage of the current heap capacity.
1967 size_t capacity_bytes = _g1->capacity();
1968 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1969 }
1970
1971 void G1CollectorPolicy::maybe_start_marking() {
1972 if (need_to_start_conc_mark("end of GC")) {
1973 // Note: this might have already been set, if during the last
1974 // pause we decided to start a cycle but at the beginning of
1975 // this pause we decided to postpone it. That's OK.
1976 collector_state()->set_initiate_conc_mark_if_possible(true);
1977 }
1978 }
1979
1980 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
1981 assert(!collector_state()->full_collection(), "must be");
1982 if (collector_state()->during_initial_mark_pause()) {
1983 assert(collector_state()->last_gc_was_young(), "must be");
1984 assert(!collector_state()->last_young_gc(), "must be");
1985 return InitialMarkGC;
1986 } else if (collector_state()->last_young_gc()) {
1987 assert(!collector_state()->during_initial_mark_pause(), "must be");
1988 assert(collector_state()->last_gc_was_young(), "must be");
1989 return LastYoungGC;
1990 } else if (!collector_state()->last_gc_was_young()) {
1991 assert(!collector_state()->during_initial_mark_pause(), "must be");
1992 assert(!collector_state()->last_young_gc(), "must be");
1993 return MixedGC;
1994 } else {
1995 assert(collector_state()->last_gc_was_young(), "must be");
1996 assert(!collector_state()->during_initial_mark_pause(), "must be");
1997 assert(!collector_state()->last_young_gc(), "must be");
1998 return YoungOnlyGC;
1999 }
2000 }
2001
2002 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2003 // Manage the MMU tracker. For some reason it ignores Full GCs.
2004 if (kind != FullGC) {
2005 _mmu_tracker->add_pause(start, end);
2006 }
2007 // Manage the mutator time tracking from initial mark to first mixed gc.
2008 switch (kind) {
2009 case FullGC:
2010 abort_time_to_mixed_tracking();
2011 break;
2012 case Cleanup:
2013 case Remark:
2014 case YoungOnlyGC:
2015 case LastYoungGC:
2016 _initial_mark_to_mixed.add_pause(end - start);
2017 break;
2018 case InitialMarkGC:
2019 _initial_mark_to_mixed.record_initial_mark_end(end);
2020 break;
2021 case MixedGC:
2022 _initial_mark_to_mixed.record_mixed_gc_start(start);
2023 break;
2024 default:
2025 ShouldNotReachHere();
2026 }
2027 }
2028
2029 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2030 _initial_mark_to_mixed.reset();
2031 }
2032
2033 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2034 const char* false_action_str) const {
2035 if (cset_chooser()->is_empty()) {
2036 log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
2037 return false;
2038 }
2039
2040 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2041 size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2042 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2043 double threshold = (double) G1HeapWastePercent;
2044 if (reclaimable_perc <= threshold) {
2045 log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
2046 false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2047 return false;
2048 }
2049 log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
2050 true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2051 return true;
2052 }
2053
2054 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2055 // The min old CSet region bound is based on the maximum desired
2056 // number of mixed GCs after a cycle. I.e., even if some old regions
2057 // look expensive, we should add them to the CSet anyway to make
2058 // sure we go through the available old regions in no more than the
2059 // maximum desired number of mixed GCs.
2060 //
2061 // The calculation is based on the number of marked regions we added
2062 // to the CSet chooser in the first place, not how many remain, so
2063 // that the result is the same during all mixed GCs that follow a cycle.
2064
2065 const size_t region_num = (size_t) cset_chooser()->length();
2066 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2067 size_t result = region_num / gc_num;
2068 // emulate ceiling
2069 if (result * gc_num < region_num) {
2070 result += 1;
2071 }
2072 return (uint) result;
2073 }
2074
2075 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2076 // The max old CSet region bound is based on the threshold expressed
2077 // as a percentage of the heap size. I.e., it should bound the
2078 // number of old regions added to the CSet irrespective of how many
2079 // of them are available.
2080
2081 const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2082 const size_t region_num = g1h->num_regions();
2083 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2084 size_t result = region_num * perc / 100;
2085 // emulate ceiling
2086 if (100 * result < region_num * perc) {
2087 result += 1;
2088 }
2089 return (uint) result;
2090 }
2091
2092
2093 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2094 double young_start_time_sec = os::elapsedTime();
2095
2096 YoungList* young_list = _g1->young_list();
2097 finalize_incremental_cset_building();
2098
2099 guarantee(target_pause_time_ms > 0.0,
2100 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2101 guarantee(_collection_set == NULL, "Precondition");
2102
2103 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2104 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2105
2106 log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
2107 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2108
2109 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2110
2111 if (collector_state()->last_gc_was_young()) {
2112 _trace_young_gen_time_data.increment_young_collection_count();
2113 } else {
2114 _trace_young_gen_time_data.increment_mixed_collection_count();
2115 }
2116
2117 // The young list is laid with the survivor regions from the previous
2118 // pause are appended to the RHS of the young list, i.e.
2119 // [Newly Young Regions ++ Survivors from last pause].
2120
2121 uint survivor_region_length = young_list->survivor_length();
2122 uint eden_region_length = young_list->eden_length();
2123 init_cset_region_lengths(eden_region_length, survivor_region_length);
2124
2125 HeapRegion* hr = young_list->first_survivor_region();
2126 while (hr != NULL) {
2127 assert(hr->is_survivor(), "badly formed young list");
2128 // There is a convention that all the young regions in the CSet
2129 // are tagged as "eden", so we do this for the survivors here. We
2130 // use the special set_eden_pre_gc() as it doesn't check that the
2131 // region is free (which is not the case here).
2132 hr->set_eden_pre_gc();
2133 hr = hr->get_next_young_region();
2134 }
2135
2136 // Clear the fields that point to the survivor list - they are all young now.
2137 young_list->clear_survivors();
2138
2139 _collection_set = _inc_cset_head;
2140 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2141 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2142
2143 log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
2144 eden_region_length, survivor_region_length, _inc_cset_predicted_elapsed_time_ms, target_pause_time_ms);
2145
2146 // The number of recorded young regions is the incremental
2147 // collection set's current size
2148 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2149
2150 double young_end_time_sec = os::elapsedTime();
2151 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2152
2153 return time_remaining_ms;
2154 }
2155
2156 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2157 double non_young_start_time_sec = os::elapsedTime();
2158 double predicted_old_time_ms = 0.0;
2159
2160
2161 if (!collector_state()->gcs_are_young()) {
2162 cset_chooser()->verify();
2163 const uint min_old_cset_length = calc_min_old_cset_length();
2164 const uint max_old_cset_length = calc_max_old_cset_length();
2165
2166 uint expensive_region_num = 0;
2167 bool check_time_remaining = adaptive_young_list_length();
2168
2169 HeapRegion* hr = cset_chooser()->peek();
2170 while (hr != NULL) {
2171 if (old_cset_region_length() >= max_old_cset_length) {
2172 // Added maximum number of old regions to the CSet.
2173 log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). old %u regions, max %u regions",
2174 old_cset_region_length(), max_old_cset_length);
2175 break;
2176 }
2177
2178
2179 // Stop adding regions if the remaining reclaimable space is
2180 // not above G1HeapWastePercent.
2181 size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2182 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2183 double threshold = (double) G1HeapWastePercent;
2184 if (reclaimable_perc <= threshold) {
2185 // We've added enough old regions that the amount of uncollected
2186 // reclaimable space is at or below the waste threshold. Stop
2187 // adding old regions to the CSet.
2188 log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). "
2189 "old %u regions, max %u regions, reclaimable: " SIZE_FORMAT "B (%1.2f%%) threshold: " UINTX_FORMAT "%%",
2190 old_cset_region_length(), max_old_cset_length, reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2191 break;
2192 }
2193
2194 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2195 if (check_time_remaining) {
2196 if (predicted_time_ms > time_remaining_ms) {
2197 // Too expensive for the current CSet.
2198
2199 if (old_cset_region_length() >= min_old_cset_length) {
2200 // We have added the minimum number of old regions to the CSet,
2201 // we are done with this CSet.
2202 log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high). "
2203 "predicted time: %1.2fms, remaining time: %1.2fms old %u regions, min %u regions",
2204 predicted_time_ms, time_remaining_ms, old_cset_region_length(), min_old_cset_length);
2205 break;
2206 }
2207
2208 // We'll add it anyway given that we haven't reached the
2209 // minimum number of old regions.
2210 expensive_region_num += 1;
2211 }
2212 } else {
2213 if (old_cset_region_length() >= min_old_cset_length) {
2214 // In the non-auto-tuning case, we'll finish adding regions
2215 // to the CSet if we reach the minimum.
2216
2217 log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min). old %u regions, min %u regions",
2218 old_cset_region_length(), min_old_cset_length);
2219 break;
2220 }
2221 }
2222
2223 // We will add this region to the CSet.
2224 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2225 predicted_old_time_ms += predicted_time_ms;
2226 cset_chooser()->pop(); // already have region via peek()
2227 _g1->old_set_remove(hr);
2228 add_old_region_to_cset(hr);
2229
2230 hr = cset_chooser()->peek();
2231 }
2232 if (hr == NULL) {
2233 log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)");
2234 }
2235
2236 if (expensive_region_num > 0) {
2237 // We print the information once here at the end, predicated on
2238 // whether we added any apparently expensive regions or not, to
2239 // avoid generating output per region.
2240 log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
2241 "old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms",
2242 old_cset_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
2243 }
2244
2245 cset_chooser()->verify();
2246 }
2247
2248 stop_incremental_cset_building();
2249
2250 log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
2251 old_cset_region_length(), predicted_old_time_ms, time_remaining_ms);
2252
2253 double non_young_end_time_sec = os::elapsedTime();
2254 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2255 }
2256
2257 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2258 if(TraceYoungGenTime) {
2259 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2260 }
2261 }
2262
2263 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2264 if(TraceYoungGenTime) {
2265 _all_yield_times_ms.add(yield_time_ms);
2266 }
2267 }
2268
2269 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2270 if(TraceYoungGenTime) {
2271 _total.add(pause_time_ms);
2272 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2273 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2274 _parallel.add(phase_times->cur_collection_par_time_ms());
2275 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2276 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2277 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2278 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2279 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2280 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2281
2282 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2283 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2284 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2285 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2286 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2287 phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2288
2289 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2290 _parallel_other.add(parallel_other_time);
2291 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2292 }
2293 }
2294
2295 void TraceYoungGenTimeData::increment_young_collection_count() {
2296 if(TraceYoungGenTime) {
2297 ++_young_pause_num;
2298 }
2299 }
2300
2301 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2302 if(TraceYoungGenTime) {
2303 ++_mixed_pause_num;
2304 }
2305 }
2306
2307 void TraceYoungGenTimeData::print_summary(const char* str,
2308 const NumberSeq* seq) const {
2309 double sum = seq->sum();
2310 tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2311 str, sum / 1000.0, seq->avg());
2312 }
2313
2314 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2315 const NumberSeq* seq) const {
2316 print_summary(str, seq);
2317 tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2318 "(num", seq->num(), seq->sd(), seq->maximum());
2319 }
2320
2321 void TraceYoungGenTimeData::print() const {
2322 if (!TraceYoungGenTime) {
2323 return;
2324 }
2325
2326 tty->print_cr("ALL PAUSES");
2327 print_summary_sd(" Total", &_total);
2328 tty->cr();
2329 tty->cr();
2330 tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2331 tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2332 tty->cr();
2333
2334 tty->print_cr("EVACUATION PAUSES");
2335
2336 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2337 tty->print_cr("none");
2338 } else {
2339 print_summary_sd(" Evacuation Pauses", &_total);
2340 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2341 print_summary(" Parallel Time", &_parallel);
2342 print_summary(" Ext Root Scanning", &_ext_root_scan);
2343 print_summary(" SATB Filtering", &_satb_filtering);
2344 print_summary(" Update RS", &_update_rs);
2345 print_summary(" Scan RS", &_scan_rs);
2346 print_summary(" Object Copy", &_obj_copy);
2347 print_summary(" Termination", &_termination);
2348 print_summary(" Parallel Other", &_parallel_other);
2349 print_summary(" Clear CT", &_clear_ct);
2350 print_summary(" Other", &_other);
2351 }
2352 tty->cr();
2353
2354 tty->print_cr("MISC");
2355 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2356 print_summary_sd(" Yields", &_all_yield_times_ms);
2357 }
2358
2359 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2360 if (TraceOldGenTime) {
2361 _all_full_gc_times.add(full_gc_time_ms);
2362 }
2363 }
2364
2365 void TraceOldGenTimeData::print() const {
2366 if (!TraceOldGenTime) {
2367 return;
2368 }
2369
2370 if (_all_full_gc_times.num() > 0) {
2371 tty->print("\n%4d full_gcs: total time = %8.2f s",
2372 _all_full_gc_times.num(),
2373 _all_full_gc_times.sum() / 1000.0);
2374 tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2375 tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2376 _all_full_gc_times.sd(),
2377 _all_full_gc_times.maximum());
2378 }
2379 }