1 /*
2 * Copyright (c) 2001, 2013, 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_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
33 #include "gc_implementation/g1/g1Log.hpp"
34 #include "gc_implementation/g1/heapRegionRemSet.hpp"
35 #include "gc_implementation/shared/gcPolicyCounters.hpp"
36 #include "runtime/arguments.hpp"
37 #include "runtime/java.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "utilities/debug.hpp"
40
41 // Different defaults for different number of GC threads
42 // They were chosen by running GCOld and SPECjbb on debris with different
43 // numbers of GC threads and choosing them based on the results
44
45 // all the same
46 static double rs_length_diff_defaults[] = {
47 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
48 };
49
50 static double cost_per_card_ms_defaults[] = {
51 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
52 };
53
54 // all the same
55 static double young_cards_per_entry_ratio_defaults[] = {
56 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
57 };
58
59 static double cost_per_entry_ms_defaults[] = {
60 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
61 };
62
63 static double cost_per_byte_ms_defaults[] = {
64 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
65 };
66
67 // these should be pretty consistent
68 static double constant_other_time_ms_defaults[] = {
69 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
70 };
71
72
73 static double young_other_cost_per_region_ms_defaults[] = {
74 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
75 };
76
77 static double non_young_other_cost_per_region_ms_defaults[] = {
78 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
79 };
80
81 G1CollectorPolicy::G1CollectorPolicy() :
82 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
83 ? ParallelGCThreads : 1),
84
85 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
86 _stop_world_start(0.0),
87
88 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
89 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
90
91 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
92 _prev_collection_pause_end_ms(0.0),
93 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
94 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
95 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
96 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
97 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _non_young_other_cost_per_region_ms_seq(
104 new TruncatedSeq(TruncatedSeqLength)),
105
106 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
108
109 _pause_time_target_ms((double) MaxGCPauseMillis),
110
111 _gcs_are_young(true),
112
113 _during_marking(false),
114 _in_marking_window(false),
115 _in_marking_window_im(false),
116
117 _recent_prev_end_times_for_all_gcs_sec(
118 new TruncatedSeq(NumPrevPausesForHeuristics)),
119
120 _recent_avg_pause_time_ratio(0.0),
121
122 _initiate_conc_mark_if_possible(false),
123 _during_initial_mark_pause(false),
124 _last_young_gc(false),
125 _last_gc_was_young(false),
126
127 _eden_bytes_before_gc(0),
128 _survivor_bytes_before_gc(0),
129 _capacity_before_gc(0),
130
131 _eden_cset_region_length(0),
132 _survivor_cset_region_length(0),
133 _old_cset_region_length(0),
134
135 _collection_set(NULL),
136 _collection_set_bytes_used_before(0),
137
138 // Incremental CSet attributes
139 _inc_cset_build_state(Inactive),
140 _inc_cset_head(NULL),
141 _inc_cset_tail(NULL),
142 _inc_cset_bytes_used_before(0),
143 _inc_cset_max_finger(NULL),
144 _inc_cset_recorded_rs_lengths(0),
145 _inc_cset_recorded_rs_lengths_diffs(0),
146 _inc_cset_predicted_elapsed_time_ms(0.0),
147 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
148
149 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
150 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
151 #endif // _MSC_VER
152
153 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
154 G1YoungSurvRateNumRegionsSummary)),
155 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
156 G1YoungSurvRateNumRegionsSummary)),
157 // add here any more surv rate groups
158 _recorded_survivor_regions(0),
159 _recorded_survivor_head(NULL),
160 _recorded_survivor_tail(NULL),
161 _survivors_age_table(true),
162
163 _gc_overhead_perc(0.0) {
164
165 // Set up the region size and associated fields. Given that the
166 // policy is created before the heap, we have to set this up here,
167 // so it's done as soon as possible.
168 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
169 HeapRegionRemSet::setup_remset_size();
170
171 G1ErgoVerbose::initialize();
172 if (PrintAdaptiveSizePolicy) {
173 // Currently, we only use a single switch for all the heuristics.
174 G1ErgoVerbose::set_enabled(true);
175 // Given that we don't currently have a verboseness level
176 // parameter, we'll hardcode this to high. This can be easily
177 // changed in the future.
178 G1ErgoVerbose::set_level(ErgoHigh);
179 } else {
180 G1ErgoVerbose::set_enabled(false);
181 }
182
183 // Verify PLAB sizes
184 const size_t region_size = HeapRegion::GrainWords;
185 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
186 char buffer[128];
187 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
188 OldPLABSize > region_size ? "Old" : "Young", region_size);
189 vm_exit_during_initialization(buffer);
190 }
191
192 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
193 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
194
195 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
196
197 int index = MIN2(_parallel_gc_threads - 1, 7);
198
199 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
200 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
201 _young_cards_per_entry_ratio_seq->add(
202 young_cards_per_entry_ratio_defaults[index]);
203 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
204 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
205 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
206 _young_other_cost_per_region_ms_seq->add(
207 young_other_cost_per_region_ms_defaults[index]);
208 _non_young_other_cost_per_region_ms_seq->add(
209 non_young_other_cost_per_region_ms_defaults[index]);
210
211 // Below, we might need to calculate the pause time target based on
212 // the pause interval. When we do so we are going to give G1 maximum
213 // flexibility and allow it to do pauses when it needs to. So, we'll
214 // arrange that the pause interval to be pause time target + 1 to
215 // ensure that a) the pause time target is maximized with respect to
216 // the pause interval and b) we maintain the invariant that pause
217 // time target < pause interval. If the user does not want this
218 // maximum flexibility, they will have to set the pause interval
219 // explicitly.
220
221 // First make sure that, if either parameter is set, its value is
222 // reasonable.
223 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
224 if (MaxGCPauseMillis < 1) {
225 vm_exit_during_initialization("MaxGCPauseMillis should be "
226 "greater than 0");
227 }
228 }
229 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
230 if (GCPauseIntervalMillis < 1) {
231 vm_exit_during_initialization("GCPauseIntervalMillis should be "
232 "greater than 0");
233 }
234 }
235
236 // Then, if the pause time target parameter was not set, set it to
237 // the default value.
238 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
239 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
240 // The default pause time target in G1 is 200ms
241 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
242 } else {
243 // We do not allow the pause interval to be set without the
244 // pause time target
245 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
246 "without setting MaxGCPauseMillis");
247 }
248 }
249
250 // Then, if the interval parameter was not set, set it according to
251 // the pause time target (this will also deal with the case when the
252 // pause time target is the default value).
253 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
254 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
255 }
256
257 // Finally, make sure that the two parameters are consistent.
258 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
259 char buffer[256];
260 jio_snprintf(buffer, 256,
261 "MaxGCPauseMillis (%u) should be less than "
262 "GCPauseIntervalMillis (%u)",
263 MaxGCPauseMillis, GCPauseIntervalMillis);
264 vm_exit_during_initialization(buffer);
265 }
266
267 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
268 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
269 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
270
271 uintx confidence_perc = G1ConfidencePercent;
272 // Put an artificial ceiling on this so that it's not set to a silly value.
273 if (confidence_perc > 100) {
274 confidence_perc = 100;
275 warning("G1ConfidencePercent is set to a value that is too large, "
276 "it's been updated to %u", confidence_perc);
277 }
278 _sigma = (double) confidence_perc / 100.0;
279
280 // start conservatively (around 50ms is about right)
281 _concurrent_mark_remark_times_ms->add(0.05);
282 _concurrent_mark_cleanup_times_ms->add(0.20);
283 _tenuring_threshold = MaxTenuringThreshold;
284 // _max_survivor_regions will be calculated by
285 // update_young_list_target_length() during initialization.
286 _max_survivor_regions = 0;
287
288 assert(GCTimeRatio > 0,
289 "we should have set it to a default value set_g1_gc_flags() "
290 "if a user set it to 0");
291 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
292
293 uintx reserve_perc = G1ReservePercent;
294 // Put an artificial ceiling on this so that it's not set to a silly value.
295 if (reserve_perc > 50) {
296 reserve_perc = 50;
297 warning("G1ReservePercent is set to a value that is too large, "
298 "it's been updated to %u", reserve_perc);
299 }
300 _reserve_factor = (double) reserve_perc / 100.0;
301 // This will be set when the heap is expanded
302 // for the first time during initialization.
303 _reserve_regions = 0;
304
305 initialize_all();
306 _collectionSetChooser = new CollectionSetChooser();
307 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
308 }
309
310 void G1CollectorPolicy::initialize_flags() {
311 set_min_alignment(HeapRegion::GrainBytes);
312 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
313 if (SurvivorRatio < 1) {
314 vm_exit_during_initialization("Invalid survivor ratio specified");
315 }
316 CollectorPolicy::initialize_flags();
317 }
318
319 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
320 assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max");
321 assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds");
322 assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds");
323
324 if (FLAG_IS_CMDLINE(NewRatio)) {
325 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
326 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
327 } else {
328 _sizer_kind = SizerNewRatio;
329 _adaptive_size = false;
330 return;
331 }
332 }
333
334 if (FLAG_IS_CMDLINE(NewSize)) {
335 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
336 1U);
337 if (FLAG_IS_CMDLINE(MaxNewSize)) {
338 _max_desired_young_length =
339 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
340 1U);
341 _sizer_kind = SizerMaxAndNewSize;
342 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
343 } else {
344 _sizer_kind = SizerNewSizeOnly;
345 }
346 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
347 _max_desired_young_length =
348 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
349 1U);
350 _sizer_kind = SizerMaxNewSizeOnly;
351 }
352 }
353
354 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
355 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
356 return MAX2(1U, default_value);
357 }
358
359 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
360 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
361 return MAX2(1U, default_value);
362 }
363
364 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
365 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
366
367 switch (_sizer_kind) {
368 case SizerDefaults:
369 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
370 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
371 break;
372 case SizerNewSizeOnly:
373 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
374 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
375 break;
376 case SizerMaxNewSizeOnly:
377 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
378 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
379 break;
380 case SizerMaxAndNewSize:
381 // Do nothing. Values set on the command line, don't update them at runtime.
382 break;
383 case SizerNewRatio:
384 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
385 _max_desired_young_length = _min_desired_young_length;
386 break;
387 default:
388 ShouldNotReachHere();
389 }
390
391 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
392 }
393
394 void G1CollectorPolicy::init() {
395 // Set aside an initial future to_space.
396 _g1 = G1CollectedHeap::heap();
397
398 assert(Heap_lock->owned_by_self(), "Locking discipline.");
399
400 initialize_gc_policy_counters();
401
402 if (adaptive_young_list_length()) {
403 _young_list_fixed_length = 0;
404 } else {
405 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
406 }
407 _free_regions_at_end_of_collection = _g1->free_regions();
408 update_young_list_target_length();
409
410 // We may immediately start allocating regions and placing them on the
411 // collection set list. Initialize the per-collection set info
412 start_incremental_cset_building();
413 }
414
415 // Create the jstat counters for the policy.
416 void G1CollectorPolicy::initialize_gc_policy_counters() {
417 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
418 }
419
420 bool G1CollectorPolicy::predict_will_fit(uint young_length,
421 double base_time_ms,
422 uint base_free_regions,
423 double target_pause_time_ms) {
424 if (young_length >= base_free_regions) {
425 // end condition 1: not enough space for the young regions
426 return false;
427 }
428
429 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
430 size_t bytes_to_copy =
431 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
432 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
433 double young_other_time_ms = predict_young_other_time_ms(young_length);
434 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
435 if (pause_time_ms > target_pause_time_ms) {
436 // end condition 2: prediction is over the target pause time
437 return false;
438 }
439
440 size_t free_bytes =
441 (base_free_regions - young_length) * HeapRegion::GrainBytes;
442 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
443 // end condition 3: out-of-space (conservatively!)
444 return false;
445 }
446
447 // success!
448 return true;
449 }
450
451 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
452 // re-calculate the necessary reserve
453 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
454 // We use ceiling so that if reserve_regions_d is > 0.0 (but
455 // smaller than 1.0) we'll get 1.
456 _reserve_regions = (uint) ceil(reserve_regions_d);
457
458 _young_gen_sizer->heap_size_changed(new_number_of_regions);
459 }
460
461 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
462 uint base_min_length) {
463 uint desired_min_length = 0;
464 if (adaptive_young_list_length()) {
465 if (_alloc_rate_ms_seq->num() > 3) {
466 double now_sec = os::elapsedTime();
467 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
468 double alloc_rate_ms = predict_alloc_rate_ms();
469 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
470 } else {
471 // otherwise we don't have enough info to make the prediction
472 }
473 }
474 desired_min_length += base_min_length;
475 // make sure we don't go below any user-defined minimum bound
476 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
477 }
478
479 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
480 // Here, we might want to also take into account any additional
481 // constraints (i.e., user-defined minimum bound). Currently, we
482 // effectively don't set this bound.
483 return _young_gen_sizer->max_desired_young_length();
484 }
485
486 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
487 if (rs_lengths == (size_t) -1) {
488 // if it's set to the default value (-1), we should predict it;
489 // otherwise, use the given value.
490 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
491 }
492
493 // Calculate the absolute and desired min bounds.
494
495 // This is how many young regions we already have (currently: the survivors).
496 uint base_min_length = recorded_survivor_regions();
497 // This is the absolute minimum young length, which ensures that we
498 // can allocate one eden region in the worst-case.
499 uint absolute_min_length = base_min_length + 1;
500 uint desired_min_length =
501 calculate_young_list_desired_min_length(base_min_length);
502 if (desired_min_length < absolute_min_length) {
503 desired_min_length = absolute_min_length;
504 }
505
506 // Calculate the absolute and desired max bounds.
507
508 // We will try our best not to "eat" into the reserve.
509 uint absolute_max_length = 0;
510 if (_free_regions_at_end_of_collection > _reserve_regions) {
511 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
512 }
513 uint desired_max_length = calculate_young_list_desired_max_length();
514 if (desired_max_length > absolute_max_length) {
515 desired_max_length = absolute_max_length;
516 }
517
518 uint young_list_target_length = 0;
519 if (adaptive_young_list_length()) {
520 if (gcs_are_young()) {
521 young_list_target_length =
522 calculate_young_list_target_length(rs_lengths,
523 base_min_length,
524 desired_min_length,
525 desired_max_length);
526 _rs_lengths_prediction = rs_lengths;
527 } else {
528 // Don't calculate anything and let the code below bound it to
529 // the desired_min_length, i.e., do the next GC as soon as
530 // possible to maximize how many old regions we can add to it.
531 }
532 } else {
533 // The user asked for a fixed young gen so we'll fix the young gen
534 // whether the next GC is young or mixed.
535 young_list_target_length = _young_list_fixed_length;
536 }
537
538 // Make sure we don't go over the desired max length, nor under the
539 // desired min length. In case they clash, desired_min_length wins
540 // which is why that test is second.
541 if (young_list_target_length > desired_max_length) {
542 young_list_target_length = desired_max_length;
543 }
544 if (young_list_target_length < desired_min_length) {
545 young_list_target_length = desired_min_length;
546 }
547
548 assert(young_list_target_length > recorded_survivor_regions(),
549 "we should be able to allocate at least one eden region");
550 assert(young_list_target_length >= absolute_min_length, "post-condition");
551 _young_list_target_length = young_list_target_length;
552
553 update_max_gc_locker_expansion();
554 }
555
556 uint
557 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
558 uint base_min_length,
559 uint desired_min_length,
560 uint desired_max_length) {
561 assert(adaptive_young_list_length(), "pre-condition");
562 assert(gcs_are_young(), "only call this for young GCs");
563
564 // In case some edge-condition makes the desired max length too small...
565 if (desired_max_length <= desired_min_length) {
566 return desired_min_length;
567 }
568
569 // We'll adjust min_young_length and max_young_length not to include
570 // the already allocated young regions (i.e., so they reflect the
571 // min and max eden regions we'll allocate). The base_min_length
572 // will be reflected in the predictions by the
573 // survivor_regions_evac_time prediction.
574 assert(desired_min_length > base_min_length, "invariant");
575 uint min_young_length = desired_min_length - base_min_length;
576 assert(desired_max_length > base_min_length, "invariant");
577 uint max_young_length = desired_max_length - base_min_length;
578
579 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
580 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
581 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
582 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
583 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
584 double base_time_ms =
585 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
586 survivor_regions_evac_time;
587 uint available_free_regions = _free_regions_at_end_of_collection;
588 uint base_free_regions = 0;
589 if (available_free_regions > _reserve_regions) {
590 base_free_regions = available_free_regions - _reserve_regions;
591 }
592
593 // Here, we will make sure that the shortest young length that
594 // makes sense fits within the target pause time.
595
596 if (predict_will_fit(min_young_length, base_time_ms,
597 base_free_regions, target_pause_time_ms)) {
598 // The shortest young length will fit into the target pause time;
599 // we'll now check whether the absolute maximum number of young
600 // regions will fit in the target pause time. If not, we'll do
601 // a binary search between min_young_length and max_young_length.
602 if (predict_will_fit(max_young_length, base_time_ms,
603 base_free_regions, target_pause_time_ms)) {
604 // The maximum young length will fit into the target pause time.
605 // We are done so set min young length to the maximum length (as
606 // the result is assumed to be returned in min_young_length).
607 min_young_length = max_young_length;
608 } else {
609 // The maximum possible number of young regions will not fit within
610 // the target pause time so we'll search for the optimal
611 // length. The loop invariants are:
612 //
613 // min_young_length < max_young_length
614 // min_young_length is known to fit into the target pause time
615 // max_young_length is known not to fit into the target pause time
616 //
617 // Going into the loop we know the above hold as we've just
618 // checked them. Every time around the loop we check whether
619 // the middle value between min_young_length and
620 // max_young_length fits into the target pause time. If it
621 // does, it becomes the new min. If it doesn't, it becomes
622 // the new max. This way we maintain the loop invariants.
623
624 assert(min_young_length < max_young_length, "invariant");
625 uint diff = (max_young_length - min_young_length) / 2;
626 while (diff > 0) {
627 uint young_length = min_young_length + diff;
628 if (predict_will_fit(young_length, base_time_ms,
629 base_free_regions, target_pause_time_ms)) {
630 min_young_length = young_length;
631 } else {
632 max_young_length = young_length;
633 }
634 assert(min_young_length < max_young_length, "invariant");
635 diff = (max_young_length - min_young_length) / 2;
636 }
637 // The results is min_young_length which, according to the
638 // loop invariants, should fit within the target pause time.
639
640 // These are the post-conditions of the binary search above:
641 assert(min_young_length < max_young_length,
642 "otherwise we should have discovered that max_young_length "
643 "fits into the pause target and not done the binary search");
644 assert(predict_will_fit(min_young_length, base_time_ms,
645 base_free_regions, target_pause_time_ms),
646 "min_young_length, the result of the binary search, should "
647 "fit into the pause target");
648 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
649 base_free_regions, target_pause_time_ms),
650 "min_young_length, the result of the binary search, should be "
651 "optimal, so no larger length should fit into the pause target");
652 }
653 } else {
654 // Even the minimum length doesn't fit into the pause time
655 // target, return it as the result nevertheless.
656 }
657 return base_min_length + min_young_length;
658 }
659
660 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
661 double survivor_regions_evac_time = 0.0;
662 for (HeapRegion * r = _recorded_survivor_head;
663 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
664 r = r->get_next_young_region()) {
665 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
666 }
667 return survivor_regions_evac_time;
668 }
669
670 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
671 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
672
673 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
674 if (rs_lengths > _rs_lengths_prediction) {
675 // add 10% to avoid having to recalculate often
676 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
677 update_young_list_target_length(rs_lengths_prediction);
678 }
679 }
680
681
682
683 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
684 bool is_tlab,
685 bool* gc_overhead_limit_was_exceeded) {
686 guarantee(false, "Not using this policy feature yet.");
687 return NULL;
688 }
689
690 // This method controls how a collector handles one or more
691 // of its generations being fully allocated.
692 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
693 bool is_tlab) {
694 guarantee(false, "Not using this policy feature yet.");
695 return NULL;
696 }
697
698
699 #ifndef PRODUCT
700 bool G1CollectorPolicy::verify_young_ages() {
701 HeapRegion* head = _g1->young_list()->first_region();
702 return
703 verify_young_ages(head, _short_lived_surv_rate_group);
704 // also call verify_young_ages on any additional surv rate groups
705 }
706
707 bool
708 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
709 SurvRateGroup *surv_rate_group) {
710 guarantee( surv_rate_group != NULL, "pre-condition" );
711
712 const char* name = surv_rate_group->name();
713 bool ret = true;
714 int prev_age = -1;
715
716 for (HeapRegion* curr = head;
717 curr != NULL;
718 curr = curr->get_next_young_region()) {
719 SurvRateGroup* group = curr->surv_rate_group();
720 if (group == NULL && !curr->is_survivor()) {
721 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
722 ret = false;
723 }
724
725 if (surv_rate_group == group) {
726 int age = curr->age_in_surv_rate_group();
727
728 if (age < 0) {
729 gclog_or_tty->print_cr("## %s: encountered negative age", name);
730 ret = false;
731 }
732
733 if (age <= prev_age) {
734 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
735 "(%d, %d)", name, age, prev_age);
736 ret = false;
737 }
738 prev_age = age;
739 }
740 }
741
742 return ret;
743 }
744 #endif // PRODUCT
745
746 void G1CollectorPolicy::record_full_collection_start() {
747 _full_collection_start_sec = os::elapsedTime();
748 record_heap_size_info_at_start();
749 // Release the future to-space so that it is available for compaction into.
750 _g1->set_full_collection();
751 }
752
753 void G1CollectorPolicy::record_full_collection_end() {
754 // Consider this like a collection pause for the purposes of allocation
755 // since last pause.
756 double end_sec = os::elapsedTime();
757 double full_gc_time_sec = end_sec - _full_collection_start_sec;
758 double full_gc_time_ms = full_gc_time_sec * 1000.0;
759
760 _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
761
762 update_recent_gc_times(end_sec, full_gc_time_ms);
763
764 _g1->clear_full_collection();
765
766 // "Nuke" the heuristics that control the young/mixed GC
767 // transitions and make sure we start with young GCs after the Full GC.
768 set_gcs_are_young(true);
769 _last_young_gc = false;
770 clear_initiate_conc_mark_if_possible();
771 clear_during_initial_mark_pause();
772 _in_marking_window = false;
773 _in_marking_window_im = false;
774
775 _short_lived_surv_rate_group->start_adding_regions();
776 // also call this on any additional surv rate groups
777
778 record_survivor_regions(0, NULL, NULL);
779
780 _free_regions_at_end_of_collection = _g1->free_regions();
781 // Reset survivors SurvRateGroup.
782 _survivor_surv_rate_group->reset();
783 update_young_list_target_length();
784 _collectionSetChooser->clear();
785 }
786
787 void G1CollectorPolicy::record_stop_world_start() {
788 _stop_world_start = os::elapsedTime();
789 }
790
791 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
792 // We only need to do this here as the policy will only be applied
793 // to the GC we're about to start. so, no point is calculating this
794 // every time we calculate / recalculate the target young length.
795 update_survivors_policy();
796
797 assert(_g1->used() == _g1->recalculate_used(),
798 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
799 _g1->used(), _g1->recalculate_used()));
800
801 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
802 _trace_gen0_time_data.record_start_collection(s_w_t_ms);
803 _stop_world_start = 0.0;
804
805 record_heap_size_info_at_start();
806
807 phase_times()->record_cur_collection_start_sec(start_time_sec);
808 _pending_cards = _g1->pending_card_num();
809
810 _collection_set_bytes_used_before = 0;
811 _bytes_copied_during_gc = 0;
812
813 _last_gc_was_young = false;
814
815 // do that for any other surv rate groups
816 _short_lived_surv_rate_group->stop_adding_regions();
817 _survivors_age_table.clear();
818
819 assert( verify_young_ages(), "region age verification" );
820 }
821
822 void G1CollectorPolicy::record_concurrent_mark_init_end(double
823 mark_init_elapsed_time_ms) {
824 _during_marking = true;
825 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
826 clear_during_initial_mark_pause();
827 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
828 }
829
830 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
831 _mark_remark_start_sec = os::elapsedTime();
832 _during_marking = false;
833 }
834
835 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
836 double end_time_sec = os::elapsedTime();
837 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
838 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
839 _cur_mark_stop_world_time_ms += elapsed_time_ms;
840 _prev_collection_pause_end_ms += elapsed_time_ms;
841
842 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
843 }
844
845 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
846 _mark_cleanup_start_sec = os::elapsedTime();
847 }
848
849 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
850 _last_young_gc = true;
851 _in_marking_window = false;
852 }
853
854 void G1CollectorPolicy::record_concurrent_pause() {
855 if (_stop_world_start > 0.0) {
856 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
857 _trace_gen0_time_data.record_yield_time(yield_ms);
858 }
859 }
860
861 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
862 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
863 return false;
864 }
865
866 size_t marking_initiating_used_threshold =
867 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
868 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
869 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
870
871 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
872 if (gcs_are_young()) {
873 ergo_verbose5(ErgoConcCycles,
874 "request concurrent cycle initiation",
875 ergo_format_reason("occupancy higher than threshold")
876 ergo_format_byte("occupancy")
877 ergo_format_byte("allocation request")
878 ergo_format_byte_perc("threshold")
879 ergo_format_str("source"),
880 cur_used_bytes,
881 alloc_byte_size,
882 marking_initiating_used_threshold,
883 (double) InitiatingHeapOccupancyPercent,
884 source);
885 return true;
886 } else {
887 ergo_verbose5(ErgoConcCycles,
888 "do not request concurrent cycle initiation",
889 ergo_format_reason("still doing mixed collections")
890 ergo_format_byte("occupancy")
891 ergo_format_byte("allocation request")
892 ergo_format_byte_perc("threshold")
893 ergo_format_str("source"),
894 cur_used_bytes,
895 alloc_byte_size,
896 marking_initiating_used_threshold,
897 (double) InitiatingHeapOccupancyPercent,
898 source);
899 }
900 }
901
902 return false;
903 }
904
905 // Anything below that is considered to be zero
906 #define MIN_TIMER_GRANULARITY 0.0000001
907
908 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
909 double end_time_sec = os::elapsedTime();
910 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
911 "otherwise, the subtraction below does not make sense");
912 size_t rs_size =
913 _cur_collection_pause_used_regions_at_start - cset_region_length();
914 size_t cur_used_bytes = _g1->used();
915 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
916 bool last_pause_included_initial_mark = false;
917 bool update_stats = !_g1->evacuation_failed();
918
919 #ifndef PRODUCT
920 if (G1YoungSurvRateVerbose) {
921 gclog_or_tty->print_cr("");
922 _short_lived_surv_rate_group->print();
923 // do that for any other surv rate groups too
924 }
925 #endif // PRODUCT
926
927 last_pause_included_initial_mark = during_initial_mark_pause();
928 if (last_pause_included_initial_mark) {
929 record_concurrent_mark_init_end(0.0);
930 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
931 // Note: this might have already been set, if during the last
932 // pause we decided to start a cycle but at the beginning of
933 // this pause we decided to postpone it. That's OK.
934 set_initiate_conc_mark_if_possible();
935 }
936
937 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
938 end_time_sec, false);
939
940 size_t freed_bytes =
941 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
942 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
943
944 double survival_fraction =
945 (double)surviving_bytes/
946 (double)_collection_set_bytes_used_before;
947
948 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
949 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
950
951 if (update_stats) {
952 _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
953 // this is where we update the allocation rate of the application
954 double app_time_ms =
955 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
956 if (app_time_ms < MIN_TIMER_GRANULARITY) {
957 // This usually happens due to the timer not having the required
958 // granularity. Some Linuxes are the usual culprits.
959 // We'll just set it to something (arbitrarily) small.
960 app_time_ms = 1.0;
961 }
962 // We maintain the invariant that all objects allocated by mutator
963 // threads will be allocated out of eden regions. So, we can use
964 // the eden region number allocated since the previous GC to
965 // calculate the application's allocate rate. The only exception
966 // to that is humongous objects that are allocated separately. But
967 // given that humongous object allocations do not really affect
968 // either the pause's duration nor when the next pause will take
969 // place we can safely ignore them here.
970 uint regions_allocated = eden_cset_region_length();
971 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
972 _alloc_rate_ms_seq->add(alloc_rate_ms);
973
974 double interval_ms =
975 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
976 update_recent_gc_times(end_time_sec, pause_time_ms);
977 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
978 if (recent_avg_pause_time_ratio() < 0.0 ||
979 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
980 #ifndef PRODUCT
981 // Dump info to allow post-facto debugging
982 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
983 gclog_or_tty->print_cr("-------------------------------------------");
984 gclog_or_tty->print_cr("Recent GC Times (ms):");
985 _recent_gc_times_ms->dump();
986 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
987 _recent_prev_end_times_for_all_gcs_sec->dump();
988 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
989 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
990 // In debug mode, terminate the JVM if the user wants to debug at this point.
991 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
992 #endif // !PRODUCT
993 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
994 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
995 if (_recent_avg_pause_time_ratio < 0.0) {
996 _recent_avg_pause_time_ratio = 0.0;
997 } else {
998 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
999 _recent_avg_pause_time_ratio = 1.0;
1000 }
1001 }
1002 }
1003 bool new_in_marking_window = _in_marking_window;
1004 bool new_in_marking_window_im = false;
1005 if (during_initial_mark_pause()) {
1006 new_in_marking_window = true;
1007 new_in_marking_window_im = true;
1008 }
1009
1010 if (_last_young_gc) {
1011 // This is supposed to to be the "last young GC" before we start
1012 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1013
1014 if (!last_pause_included_initial_mark) {
1015 if (next_gc_should_be_mixed("start mixed GCs",
1016 "do not start mixed GCs")) {
1017 set_gcs_are_young(false);
1018 }
1019 } else {
1020 ergo_verbose0(ErgoMixedGCs,
1021 "do not start mixed GCs",
1022 ergo_format_reason("concurrent cycle is about to start"));
1023 }
1024 _last_young_gc = false;
1025 }
1026
1027 if (!_last_gc_was_young) {
1028 // This is a mixed GC. Here we decide whether to continue doing
1029 // mixed GCs or not.
1030
1031 if (!next_gc_should_be_mixed("continue mixed GCs",
1032 "do not continue mixed GCs")) {
1033 set_gcs_are_young(true);
1034 }
1035 }
1036
1037 _short_lived_surv_rate_group->start_adding_regions();
1038 // do that for any other surv rate groupsx
1039
1040 if (update_stats) {
1041 double cost_per_card_ms = 0.0;
1042 if (_pending_cards > 0) {
1043 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1044 _cost_per_card_ms_seq->add(cost_per_card_ms);
1045 }
1046
1047 size_t cards_scanned = _g1->cards_scanned();
1048
1049 double cost_per_entry_ms = 0.0;
1050 if (cards_scanned > 10) {
1051 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1052 if (_last_gc_was_young) {
1053 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1054 } else {
1055 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1056 }
1057 }
1058
1059 if (_max_rs_lengths > 0) {
1060 double cards_per_entry_ratio =
1061 (double) cards_scanned / (double) _max_rs_lengths;
1062 if (_last_gc_was_young) {
1063 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1064 } else {
1065 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1066 }
1067 }
1068
1069 // This is defensive. For a while _max_rs_lengths could get
1070 // smaller than _recorded_rs_lengths which was causing
1071 // rs_length_diff to get very large and mess up the RSet length
1072 // predictions. The reason was unsafe concurrent updates to the
1073 // _inc_cset_recorded_rs_lengths field which the code below guards
1074 // against (see CR 7118202). This bug has now been fixed (see CR
1075 // 7119027). However, I'm still worried that
1076 // _inc_cset_recorded_rs_lengths might still end up somewhat
1077 // inaccurate. The concurrent refinement thread calculates an
1078 // RSet's length concurrently with other CR threads updating it
1079 // which might cause it to calculate the length incorrectly (if,
1080 // say, it's in mid-coarsening). So I'll leave in the defensive
1081 // conditional below just in case.
1082 size_t rs_length_diff = 0;
1083 if (_max_rs_lengths > _recorded_rs_lengths) {
1084 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1085 }
1086 _rs_length_diff_seq->add((double) rs_length_diff);
1087
1088 size_t copied_bytes = surviving_bytes;
1089 double cost_per_byte_ms = 0.0;
1090 if (copied_bytes > 0) {
1091 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1092 if (_in_marking_window) {
1093 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1094 } else {
1095 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1096 }
1097 }
1098
1099 double all_other_time_ms = pause_time_ms -
1100 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1101 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1102
1103 double young_other_time_ms = 0.0;
1104 if (young_cset_region_length() > 0) {
1105 young_other_time_ms =
1106 phase_times()->young_cset_choice_time_ms() +
1107 phase_times()->young_free_cset_time_ms();
1108 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1109 (double) young_cset_region_length());
1110 }
1111 double non_young_other_time_ms = 0.0;
1112 if (old_cset_region_length() > 0) {
1113 non_young_other_time_ms =
1114 phase_times()->non_young_cset_choice_time_ms() +
1115 phase_times()->non_young_free_cset_time_ms();
1116
1117 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1118 (double) old_cset_region_length());
1119 }
1120
1121 double constant_other_time_ms = all_other_time_ms -
1122 (young_other_time_ms + non_young_other_time_ms);
1123 _constant_other_time_ms_seq->add(constant_other_time_ms);
1124
1125 double survival_ratio = 0.0;
1126 if (_collection_set_bytes_used_before > 0) {
1127 survival_ratio = (double) _bytes_copied_during_gc /
1128 (double) _collection_set_bytes_used_before;
1129 }
1130
1131 _pending_cards_seq->add((double) _pending_cards);
1132 _rs_lengths_seq->add((double) _max_rs_lengths);
1133 }
1134
1135 _in_marking_window = new_in_marking_window;
1136 _in_marking_window_im = new_in_marking_window_im;
1137 _free_regions_at_end_of_collection = _g1->free_regions();
1138 update_young_list_target_length();
1139
1140 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1141 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1142 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1143 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1144
1145 _collectionSetChooser->verify();
1146 }
1147
1148 #define EXT_SIZE_FORMAT "%.1f%s"
1149 #define EXT_SIZE_PARAMS(bytes) \
1150 byte_size_in_proper_unit((double)(bytes)), \
1151 proper_unit_for_byte_size((bytes))
1152
1153 void G1CollectorPolicy::record_heap_size_info_at_start() {
1154 YoungList* young_list = _g1->young_list();
1155 _eden_bytes_before_gc = young_list->eden_used_bytes();
1156 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
1157 _capacity_before_gc = _g1->capacity();
1158
1159 _cur_collection_pause_used_at_start_bytes = _g1->used();
1160 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
1161
1162 size_t eden_capacity_before_gc =
1163 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_bytes_before_gc;
1164
1165 _prev_eden_capacity = eden_capacity_before_gc;
1166 }
1167
1168 void G1CollectorPolicy::print_heap_transition() {
1169 _g1->print_size_transition(gclog_or_tty,
1170 _cur_collection_pause_used_at_start_bytes, _g1->used(), _g1->capacity());
1171 }
1172
1173 void G1CollectorPolicy::print_detailed_heap_transition() {
1174 YoungList* young_list = _g1->young_list();
1175 size_t eden_bytes = young_list->eden_used_bytes();
1176 size_t survivor_bytes = young_list->survivor_used_bytes();
1177 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1178 size_t used = _g1->used();
1179 size_t capacity = _g1->capacity();
1180 size_t eden_capacity =
1181 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1182
1183 gclog_or_tty->print_cr(
1184 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1185 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1186 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1187 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1188 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1189 EXT_SIZE_PARAMS(_prev_eden_capacity),
1190 EXT_SIZE_PARAMS(eden_bytes),
1191 EXT_SIZE_PARAMS(eden_capacity),
1192 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1193 EXT_SIZE_PARAMS(survivor_bytes),
1194 EXT_SIZE_PARAMS(used_before_gc),
1195 EXT_SIZE_PARAMS(_capacity_before_gc),
1196 EXT_SIZE_PARAMS(used),
1197 EXT_SIZE_PARAMS(capacity));
1198 }
1199
1200 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1201 double update_rs_processed_buffers,
1202 double goal_ms) {
1203 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1204 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1205
1206 if (G1UseAdaptiveConcRefinement) {
1207 const int k_gy = 3, k_gr = 6;
1208 const double inc_k = 1.1, dec_k = 0.9;
1209
1210 int g = cg1r->green_zone();
1211 if (update_rs_time > goal_ms) {
1212 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1213 } else {
1214 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1215 g = (int)MAX2(g * inc_k, g + 1.0);
1216 }
1217 }
1218 // Change the refinement threads params
1219 cg1r->set_green_zone(g);
1220 cg1r->set_yellow_zone(g * k_gy);
1221 cg1r->set_red_zone(g * k_gr);
1222 cg1r->reinitialize_threads();
1223
1224 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1225 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1226 cg1r->yellow_zone());
1227 // Change the barrier params
1228 dcqs.set_process_completed_threshold(processing_threshold);
1229 dcqs.set_max_completed_queue(cg1r->red_zone());
1230 }
1231
1232 int curr_queue_size = dcqs.completed_buffers_num();
1233 if (curr_queue_size >= cg1r->yellow_zone()) {
1234 dcqs.set_completed_queue_padding(curr_queue_size);
1235 } else {
1236 dcqs.set_completed_queue_padding(0);
1237 }
1238 dcqs.notify_if_necessary();
1239 }
1240
1241 double
1242 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1243 size_t scanned_cards) {
1244 return
1245 predict_rs_update_time_ms(pending_cards) +
1246 predict_rs_scan_time_ms(scanned_cards) +
1247 predict_constant_other_time_ms();
1248 }
1249
1250 double
1251 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1252 size_t rs_length = predict_rs_length_diff();
1253 size_t card_num;
1254 if (gcs_are_young()) {
1255 card_num = predict_young_card_num(rs_length);
1256 } else {
1257 card_num = predict_non_young_card_num(rs_length);
1258 }
1259 return predict_base_elapsed_time_ms(pending_cards, card_num);
1260 }
1261
1262 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1263 size_t bytes_to_copy;
1264 if (hr->is_marked())
1265 bytes_to_copy = hr->max_live_bytes();
1266 else {
1267 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1268 int age = hr->age_in_surv_rate_group();
1269 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1270 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1271 }
1272 return bytes_to_copy;
1273 }
1274
1275 double
1276 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1277 bool for_young_gc) {
1278 size_t rs_length = hr->rem_set()->occupied();
1279 size_t card_num;
1280
1281 // Predicting the number of cards is based on which type of GC
1282 // we're predicting for.
1283 if (for_young_gc) {
1284 card_num = predict_young_card_num(rs_length);
1285 } else {
1286 card_num = predict_non_young_card_num(rs_length);
1287 }
1288 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1289
1290 double region_elapsed_time_ms =
1291 predict_rs_scan_time_ms(card_num) +
1292 predict_object_copy_time_ms(bytes_to_copy);
1293
1294 // The prediction of the "other" time for this region is based
1295 // upon the region type and NOT the GC type.
1296 if (hr->is_young()) {
1297 region_elapsed_time_ms += predict_young_other_time_ms(1);
1298 } else {
1299 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1300 }
1301 return region_elapsed_time_ms;
1302 }
1303
1304 void
1305 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1306 uint survivor_cset_region_length) {
1307 _eden_cset_region_length = eden_cset_region_length;
1308 _survivor_cset_region_length = survivor_cset_region_length;
1309 _old_cset_region_length = 0;
1310 }
1311
1312 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1313 _recorded_rs_lengths = rs_lengths;
1314 }
1315
1316 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1317 double elapsed_ms) {
1318 _recent_gc_times_ms->add(elapsed_ms);
1319 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1320 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1321 }
1322
1323 size_t G1CollectorPolicy::expansion_amount() {
1324 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1325 double threshold = _gc_overhead_perc;
1326 if (recent_gc_overhead > threshold) {
1327 // We will double the existing space, or take
1328 // G1ExpandByPercentOfAvailable % of the available expansion
1329 // space, whichever is smaller, bounded below by a minimum
1330 // expansion (unless that's all that's left.)
1331 const size_t min_expand_bytes = 1*M;
1332 size_t reserved_bytes = _g1->max_capacity();
1333 size_t committed_bytes = _g1->capacity();
1334 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1335 size_t expand_bytes;
1336 size_t expand_bytes_via_pct =
1337 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1338 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1339 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1340 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1341
1342 ergo_verbose5(ErgoHeapSizing,
1343 "attempt heap expansion",
1344 ergo_format_reason("recent GC overhead higher than "
1345 "threshold after GC")
1346 ergo_format_perc("recent GC overhead")
1347 ergo_format_perc("threshold")
1348 ergo_format_byte("uncommitted")
1349 ergo_format_byte_perc("calculated expansion amount"),
1350 recent_gc_overhead, threshold,
1351 uncommitted_bytes,
1352 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1353
1354 return expand_bytes;
1355 } else {
1356 return 0;
1357 }
1358 }
1359
1360 void G1CollectorPolicy::print_tracing_info() const {
1361 _trace_gen0_time_data.print();
1362 _trace_gen1_time_data.print();
1363 }
1364
1365 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1366 #ifndef PRODUCT
1367 _short_lived_surv_rate_group->print_surv_rate_summary();
1368 // add this call for any other surv rate groups
1369 #endif // PRODUCT
1370 }
1371
1372 #ifndef PRODUCT
1373 // for debugging, bit of a hack...
1374 static char*
1375 region_num_to_mbs(int length) {
1376 static char buffer[64];
1377 double bytes = (double) (length * HeapRegion::GrainBytes);
1378 double mbs = bytes / (double) (1024 * 1024);
1379 sprintf(buffer, "%7.2lfMB", mbs);
1380 return buffer;
1381 }
1382 #endif // PRODUCT
1383
1384 uint G1CollectorPolicy::max_regions(int purpose) {
1385 switch (purpose) {
1386 case GCAllocForSurvived:
1387 return _max_survivor_regions;
1388 case GCAllocForTenured:
1389 return REGIONS_UNLIMITED;
1390 default:
1391 ShouldNotReachHere();
1392 return REGIONS_UNLIMITED;
1393 };
1394 }
1395
1396 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1397 uint expansion_region_num = 0;
1398 if (GCLockerEdenExpansionPercent > 0) {
1399 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1400 double expansion_region_num_d = perc * (double) _young_list_target_length;
1401 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1402 // less than 1.0) we'll get 1.
1403 expansion_region_num = (uint) ceil(expansion_region_num_d);
1404 } else {
1405 assert(expansion_region_num == 0, "sanity");
1406 }
1407 _young_list_max_length = _young_list_target_length + expansion_region_num;
1408 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1409 }
1410
1411 // Calculates survivor space parameters.
1412 void G1CollectorPolicy::update_survivors_policy() {
1413 double max_survivor_regions_d =
1414 (double) _young_list_target_length / (double) SurvivorRatio;
1415 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1416 // smaller than 1.0) we'll get 1.
1417 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1418
1419 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1420 HeapRegion::GrainWords * _max_survivor_regions);
1421 }
1422
1423 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1424 GCCause::Cause gc_cause) {
1425 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1426 if (!during_cycle) {
1427 ergo_verbose1(ErgoConcCycles,
1428 "request concurrent cycle initiation",
1429 ergo_format_reason("requested by GC cause")
1430 ergo_format_str("GC cause"),
1431 GCCause::to_string(gc_cause));
1432 set_initiate_conc_mark_if_possible();
1433 return true;
1434 } else {
1435 ergo_verbose1(ErgoConcCycles,
1436 "do not request concurrent cycle initiation",
1437 ergo_format_reason("concurrent cycle already in progress")
1438 ergo_format_str("GC cause"),
1439 GCCause::to_string(gc_cause));
1440 return false;
1441 }
1442 }
1443
1444 void
1445 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1446 // We are about to decide on whether this pause will be an
1447 // initial-mark pause.
1448
1449 // First, during_initial_mark_pause() should not be already set. We
1450 // will set it here if we have to. However, it should be cleared by
1451 // the end of the pause (it's only set for the duration of an
1452 // initial-mark pause).
1453 assert(!during_initial_mark_pause(), "pre-condition");
1454
1455 if (initiate_conc_mark_if_possible()) {
1456 // We had noticed on a previous pause that the heap occupancy has
1457 // gone over the initiating threshold and we should start a
1458 // concurrent marking cycle. So we might initiate one.
1459
1460 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1461 if (!during_cycle) {
1462 // The concurrent marking thread is not "during a cycle", i.e.,
1463 // it has completed the last one. So we can go ahead and
1464 // initiate a new cycle.
1465
1466 set_during_initial_mark_pause();
1467 // We do not allow mixed GCs during marking.
1468 if (!gcs_are_young()) {
1469 set_gcs_are_young(true);
1470 ergo_verbose0(ErgoMixedGCs,
1471 "end mixed GCs",
1472 ergo_format_reason("concurrent cycle is about to start"));
1473 }
1474
1475 // And we can now clear initiate_conc_mark_if_possible() as
1476 // we've already acted on it.
1477 clear_initiate_conc_mark_if_possible();
1478
1479 ergo_verbose0(ErgoConcCycles,
1480 "initiate concurrent cycle",
1481 ergo_format_reason("concurrent cycle initiation requested"));
1482 } else {
1483 // The concurrent marking thread is still finishing up the
1484 // previous cycle. If we start one right now the two cycles
1485 // overlap. In particular, the concurrent marking thread might
1486 // be in the process of clearing the next marking bitmap (which
1487 // we will use for the next cycle if we start one). Starting a
1488 // cycle now will be bad given that parts of the marking
1489 // information might get cleared by the marking thread. And we
1490 // cannot wait for the marking thread to finish the cycle as it
1491 // periodically yields while clearing the next marking bitmap
1492 // and, if it's in a yield point, it's waiting for us to
1493 // finish. So, at this point we will not start a cycle and we'll
1494 // let the concurrent marking thread complete the last one.
1495 ergo_verbose0(ErgoConcCycles,
1496 "do not initiate concurrent cycle",
1497 ergo_format_reason("concurrent cycle already in progress"));
1498 }
1499 }
1500 }
1501
1502 class KnownGarbageClosure: public HeapRegionClosure {
1503 G1CollectedHeap* _g1h;
1504 CollectionSetChooser* _hrSorted;
1505
1506 public:
1507 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1508 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1509
1510 bool doHeapRegion(HeapRegion* r) {
1511 // We only include humongous regions in collection
1512 // sets when concurrent mark shows that their contained object is
1513 // unreachable.
1514
1515 // Do we have any marking information for this region?
1516 if (r->is_marked()) {
1517 // We will skip any region that's currently used as an old GC
1518 // alloc region (we should not consider those for collection
1519 // before we fill them up).
1520 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1521 _hrSorted->add_region(r);
1522 }
1523 }
1524 return false;
1525 }
1526 };
1527
1528 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1529 G1CollectedHeap* _g1h;
1530 CSetChooserParUpdater _cset_updater;
1531
1532 public:
1533 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1534 uint chunk_size) :
1535 _g1h(G1CollectedHeap::heap()),
1536 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1537
1538 bool doHeapRegion(HeapRegion* r) {
1539 // Do we have any marking information for this region?
1540 if (r->is_marked()) {
1541 // We will skip any region that's currently used as an old GC
1542 // alloc region (we should not consider those for collection
1543 // before we fill them up).
1544 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1545 _cset_updater.add_region(r);
1546 }
1547 }
1548 return false;
1549 }
1550 };
1551
1552 class ParKnownGarbageTask: public AbstractGangTask {
1553 CollectionSetChooser* _hrSorted;
1554 uint _chunk_size;
1555 G1CollectedHeap* _g1;
1556 public:
1557 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1558 AbstractGangTask("ParKnownGarbageTask"),
1559 _hrSorted(hrSorted), _chunk_size(chunk_size),
1560 _g1(G1CollectedHeap::heap()) { }
1561
1562 void work(uint worker_id) {
1563 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1564
1565 // Back to zero for the claim value.
1566 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1567 _g1->workers()->active_workers(),
1568 HeapRegion::InitialClaimValue);
1569 }
1570 };
1571
1572 void
1573 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1574 _collectionSetChooser->clear();
1575
1576 uint region_num = _g1->n_regions();
1577 if (G1CollectedHeap::use_parallel_gc_threads()) {
1578 const uint OverpartitionFactor = 4;
1579 uint WorkUnit;
1580 // The use of MinChunkSize = 8 in the original code
1581 // causes some assertion failures when the total number of
1582 // region is less than 8. The code here tries to fix that.
1583 // Should the original code also be fixed?
1584 if (no_of_gc_threads > 0) {
1585 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1586 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1587 MinWorkUnit);
1588 } else {
1589 assert(no_of_gc_threads > 0,
1590 "The active gc workers should be greater than 0");
1591 // In a product build do something reasonable to avoid a crash.
1592 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1593 WorkUnit =
1594 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1595 MinWorkUnit);
1596 }
1597 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1598 WorkUnit);
1599 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1600 (int) WorkUnit);
1601 _g1->workers()->run_task(&parKnownGarbageTask);
1602
1603 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1604 "sanity check");
1605 } else {
1606 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1607 _g1->heap_region_iterate(&knownGarbagecl);
1608 }
1609
1610 _collectionSetChooser->sort_regions();
1611
1612 double end_sec = os::elapsedTime();
1613 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1614 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1615 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1616 _prev_collection_pause_end_ms += elapsed_time_ms;
1617 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1618 }
1619
1620 // Add the heap region at the head of the non-incremental collection set
1621 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1622 assert(_inc_cset_build_state == Active, "Precondition");
1623 assert(!hr->is_young(), "non-incremental add of young region");
1624
1625 assert(!hr->in_collection_set(), "should not already be in the CSet");
1626 hr->set_in_collection_set(true);
1627 hr->set_next_in_collection_set(_collection_set);
1628 _collection_set = hr;
1629 _collection_set_bytes_used_before += hr->used();
1630 _g1->register_region_with_in_cset_fast_test(hr);
1631 size_t rs_length = hr->rem_set()->occupied();
1632 _recorded_rs_lengths += rs_length;
1633 _old_cset_region_length += 1;
1634 }
1635
1636 // Initialize the per-collection-set information
1637 void G1CollectorPolicy::start_incremental_cset_building() {
1638 assert(_inc_cset_build_state == Inactive, "Precondition");
1639
1640 _inc_cset_head = NULL;
1641 _inc_cset_tail = NULL;
1642 _inc_cset_bytes_used_before = 0;
1643
1644 _inc_cset_max_finger = 0;
1645 _inc_cset_recorded_rs_lengths = 0;
1646 _inc_cset_recorded_rs_lengths_diffs = 0;
1647 _inc_cset_predicted_elapsed_time_ms = 0.0;
1648 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1649 _inc_cset_build_state = Active;
1650 }
1651
1652 void G1CollectorPolicy::finalize_incremental_cset_building() {
1653 assert(_inc_cset_build_state == Active, "Precondition");
1654 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1655
1656 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1657 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1658 // that adds a new region to the CSet. Further updates by the
1659 // concurrent refinement thread that samples the young RSet lengths
1660 // are accumulated in the *_diffs fields. Here we add the diffs to
1661 // the "main" fields.
1662
1663 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1664 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1665 } else {
1666 // This is defensive. The diff should in theory be always positive
1667 // as RSets can only grow between GCs. However, given that we
1668 // sample their size concurrently with other threads updating them
1669 // it's possible that we might get the wrong size back, which
1670 // could make the calculations somewhat inaccurate.
1671 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1672 if (_inc_cset_recorded_rs_lengths >= diffs) {
1673 _inc_cset_recorded_rs_lengths -= diffs;
1674 } else {
1675 _inc_cset_recorded_rs_lengths = 0;
1676 }
1677 }
1678 _inc_cset_predicted_elapsed_time_ms +=
1679 _inc_cset_predicted_elapsed_time_ms_diffs;
1680
1681 _inc_cset_recorded_rs_lengths_diffs = 0;
1682 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1683 }
1684
1685 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1686 // This routine is used when:
1687 // * adding survivor regions to the incremental cset at the end of an
1688 // evacuation pause,
1689 // * adding the current allocation region to the incremental cset
1690 // when it is retired, and
1691 // * updating existing policy information for a region in the
1692 // incremental cset via young list RSet sampling.
1693 // Therefore this routine may be called at a safepoint by the
1694 // VM thread, or in-between safepoints by mutator threads (when
1695 // retiring the current allocation region) or a concurrent
1696 // refine thread (RSet sampling).
1697
1698 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1699 size_t used_bytes = hr->used();
1700 _inc_cset_recorded_rs_lengths += rs_length;
1701 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1702 _inc_cset_bytes_used_before += used_bytes;
1703
1704 // Cache the values we have added to the aggregated informtion
1705 // in the heap region in case we have to remove this region from
1706 // the incremental collection set, or it is updated by the
1707 // rset sampling code
1708 hr->set_recorded_rs_length(rs_length);
1709 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1710 }
1711
1712 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1713 size_t new_rs_length) {
1714 // Update the CSet information that is dependent on the new RS length
1715 assert(hr->is_young(), "Precondition");
1716 assert(!SafepointSynchronize::is_at_safepoint(),
1717 "should not be at a safepoint");
1718
1719 // We could have updated _inc_cset_recorded_rs_lengths and
1720 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1721 // that atomically, as this code is executed by a concurrent
1722 // refinement thread, potentially concurrently with a mutator thread
1723 // allocating a new region and also updating the same fields. To
1724 // avoid the atomic operations we accumulate these updates on two
1725 // separate fields (*_diffs) and we'll just add them to the "main"
1726 // fields at the start of a GC.
1727
1728 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1729 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1730 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1731
1732 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1733 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1734 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1735 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1736
1737 hr->set_recorded_rs_length(new_rs_length);
1738 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1739 }
1740
1741 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1742 assert(hr->is_young(), "invariant");
1743 assert(hr->young_index_in_cset() > -1, "should have already been set");
1744 assert(_inc_cset_build_state == Active, "Precondition");
1745
1746 // We need to clear and set the cached recorded/cached collection set
1747 // information in the heap region here (before the region gets added
1748 // to the collection set). An individual heap region's cached values
1749 // are calculated, aggregated with the policy collection set info,
1750 // and cached in the heap region here (initially) and (subsequently)
1751 // by the Young List sampling code.
1752
1753 size_t rs_length = hr->rem_set()->occupied();
1754 add_to_incremental_cset_info(hr, rs_length);
1755
1756 HeapWord* hr_end = hr->end();
1757 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1758
1759 assert(!hr->in_collection_set(), "invariant");
1760 hr->set_in_collection_set(true);
1761 assert( hr->next_in_collection_set() == NULL, "invariant");
1762
1763 _g1->register_region_with_in_cset_fast_test(hr);
1764 }
1765
1766 // Add the region at the RHS of the incremental cset
1767 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1768 // We should only ever be appending survivors at the end of a pause
1769 assert( hr->is_survivor(), "Logic");
1770
1771 // Do the 'common' stuff
1772 add_region_to_incremental_cset_common(hr);
1773
1774 // Now add the region at the right hand side
1775 if (_inc_cset_tail == NULL) {
1776 assert(_inc_cset_head == NULL, "invariant");
1777 _inc_cset_head = hr;
1778 } else {
1779 _inc_cset_tail->set_next_in_collection_set(hr);
1780 }
1781 _inc_cset_tail = hr;
1782 }
1783
1784 // Add the region to the LHS of the incremental cset
1785 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1786 // Survivors should be added to the RHS at the end of a pause
1787 assert(!hr->is_survivor(), "Logic");
1788
1789 // Do the 'common' stuff
1790 add_region_to_incremental_cset_common(hr);
1791
1792 // Add the region at the left hand side
1793 hr->set_next_in_collection_set(_inc_cset_head);
1794 if (_inc_cset_head == NULL) {
1795 assert(_inc_cset_tail == NULL, "Invariant");
1796 _inc_cset_tail = hr;
1797 }
1798 _inc_cset_head = hr;
1799 }
1800
1801 #ifndef PRODUCT
1802 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1803 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1804
1805 st->print_cr("\nCollection_set:");
1806 HeapRegion* csr = list_head;
1807 while (csr != NULL) {
1808 HeapRegion* next = csr->next_in_collection_set();
1809 assert(csr->in_collection_set(), "bad CS");
1810 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1811 HR_FORMAT_PARAMS(csr),
1812 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1813 csr->age_in_surv_rate_group_cond());
1814 csr = next;
1815 }
1816 }
1817 #endif // !PRODUCT
1818
1819 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1820 // Returns the given amount of reclaimable bytes (that represents
1821 // the amount of reclaimable space still to be collected) as a
1822 // percentage of the current heap capacity.
1823 size_t capacity_bytes = _g1->capacity();
1824 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1825 }
1826
1827 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1828 const char* false_action_str) {
1829 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1830 if (cset_chooser->is_empty()) {
1831 ergo_verbose0(ErgoMixedGCs,
1832 false_action_str,
1833 ergo_format_reason("candidate old regions not available"));
1834 return false;
1835 }
1836
1837 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1838 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1839 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1840 double threshold = (double) G1HeapWastePercent;
1841 if (reclaimable_perc <= threshold) {
1842 ergo_verbose4(ErgoMixedGCs,
1843 false_action_str,
1844 ergo_format_reason("reclaimable percentage not over threshold")
1845 ergo_format_region("candidate old regions")
1846 ergo_format_byte_perc("reclaimable")
1847 ergo_format_perc("threshold"),
1848 cset_chooser->remaining_regions(),
1849 reclaimable_bytes,
1850 reclaimable_perc, threshold);
1851 return false;
1852 }
1853
1854 ergo_verbose4(ErgoMixedGCs,
1855 true_action_str,
1856 ergo_format_reason("candidate old regions available")
1857 ergo_format_region("candidate old regions")
1858 ergo_format_byte_perc("reclaimable")
1859 ergo_format_perc("threshold"),
1860 cset_chooser->remaining_regions(),
1861 reclaimable_bytes,
1862 reclaimable_perc, threshold);
1863 return true;
1864 }
1865
1866 uint G1CollectorPolicy::calc_min_old_cset_length() {
1867 // The min old CSet region bound is based on the maximum desired
1868 // number of mixed GCs after a cycle. I.e., even if some old regions
1869 // look expensive, we should add them to the CSet anyway to make
1870 // sure we go through the available old regions in no more than the
1871 // maximum desired number of mixed GCs.
1872 //
1873 // The calculation is based on the number of marked regions we added
1874 // to the CSet chooser in the first place, not how many remain, so
1875 // that the result is the same during all mixed GCs that follow a cycle.
1876
1877 const size_t region_num = (size_t) _collectionSetChooser->length();
1878 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1879 size_t result = region_num / gc_num;
1880 // emulate ceiling
1881 if (result * gc_num < region_num) {
1882 result += 1;
1883 }
1884 return (uint) result;
1885 }
1886
1887 uint G1CollectorPolicy::calc_max_old_cset_length() {
1888 // The max old CSet region bound is based on the threshold expressed
1889 // as a percentage of the heap size. I.e., it should bound the
1890 // number of old regions added to the CSet irrespective of how many
1891 // of them are available.
1892
1893 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1894 const size_t region_num = g1h->n_regions();
1895 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1896 size_t result = region_num * perc / 100;
1897 // emulate ceiling
1898 if (100 * result < region_num * perc) {
1899 result += 1;
1900 }
1901 return (uint) result;
1902 }
1903
1904 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1905 double young_start_time_sec = os::elapsedTime();
1906
1907 YoungList* young_list = _g1->young_list();
1908 finalize_incremental_cset_building();
1909
1910 guarantee(target_pause_time_ms > 0.0,
1911 err_msg("target_pause_time_ms = %1.6lf should be positive",
1912 target_pause_time_ms));
1913 guarantee(_collection_set == NULL, "Precondition");
1914
1915 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1916 double predicted_pause_time_ms = base_time_ms;
1917 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1918
1919 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1920 "start choosing CSet",
1921 ergo_format_size("_pending_cards")
1922 ergo_format_ms("predicted base time")
1923 ergo_format_ms("remaining time")
1924 ergo_format_ms("target pause time"),
1925 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1926
1927 _last_gc_was_young = gcs_are_young() ? true : false;
1928
1929 if (_last_gc_was_young) {
1930 _trace_gen0_time_data.increment_young_collection_count();
1931 } else {
1932 _trace_gen0_time_data.increment_mixed_collection_count();
1933 }
1934
1935 // The young list is laid with the survivor regions from the previous
1936 // pause are appended to the RHS of the young list, i.e.
1937 // [Newly Young Regions ++ Survivors from last pause].
1938
1939 uint survivor_region_length = young_list->survivor_length();
1940 uint eden_region_length = young_list->length() - survivor_region_length;
1941 init_cset_region_lengths(eden_region_length, survivor_region_length);
1942
1943 HeapRegion* hr = young_list->first_survivor_region();
1944 while (hr != NULL) {
1945 assert(hr->is_survivor(), "badly formed young list");
1946 hr->set_young();
1947 hr = hr->get_next_young_region();
1948 }
1949
1950 // Clear the fields that point to the survivor list - they are all young now.
1951 young_list->clear_survivors();
1952
1953 _collection_set = _inc_cset_head;
1954 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1955 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1956 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1957
1958 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1959 "add young regions to CSet",
1960 ergo_format_region("eden")
1961 ergo_format_region("survivors")
1962 ergo_format_ms("predicted young region time"),
1963 eden_region_length, survivor_region_length,
1964 _inc_cset_predicted_elapsed_time_ms);
1965
1966 // The number of recorded young regions is the incremental
1967 // collection set's current size
1968 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1969
1970 double young_end_time_sec = os::elapsedTime();
1971 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1972
1973 // Set the start of the non-young choice time.
1974 double non_young_start_time_sec = young_end_time_sec;
1975
1976 if (!gcs_are_young()) {
1977 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1978 cset_chooser->verify();
1979 const uint min_old_cset_length = calc_min_old_cset_length();
1980 const uint max_old_cset_length = calc_max_old_cset_length();
1981
1982 uint expensive_region_num = 0;
1983 bool check_time_remaining = adaptive_young_list_length();
1984
1985 HeapRegion* hr = cset_chooser->peek();
1986 while (hr != NULL) {
1987 if (old_cset_region_length() >= max_old_cset_length) {
1988 // Added maximum number of old regions to the CSet.
1989 ergo_verbose2(ErgoCSetConstruction,
1990 "finish adding old regions to CSet",
1991 ergo_format_reason("old CSet region num reached max")
1992 ergo_format_region("old")
1993 ergo_format_region("max"),
1994 old_cset_region_length(), max_old_cset_length);
1995 break;
1996 }
1997
1998
1999 // Stop adding regions if the remaining reclaimable space is
2000 // not above G1HeapWastePercent.
2001 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2002 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2003 double threshold = (double) G1HeapWastePercent;
2004 if (reclaimable_perc <= threshold) {
2005 // We've added enough old regions that the amount of uncollected
2006 // reclaimable space is at or below the waste threshold. Stop
2007 // adding old regions to the CSet.
2008 ergo_verbose5(ErgoCSetConstruction,
2009 "finish adding old regions to CSet",
2010 ergo_format_reason("reclaimable percentage not over threshold")
2011 ergo_format_region("old")
2012 ergo_format_region("max")
2013 ergo_format_byte_perc("reclaimable")
2014 ergo_format_perc("threshold"),
2015 old_cset_region_length(),
2016 max_old_cset_length,
2017 reclaimable_bytes,
2018 reclaimable_perc, threshold);
2019 break;
2020 }
2021
2022 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2023 if (check_time_remaining) {
2024 if (predicted_time_ms > time_remaining_ms) {
2025 // Too expensive for the current CSet.
2026
2027 if (old_cset_region_length() >= min_old_cset_length) {
2028 // We have added the minimum number of old regions to the CSet,
2029 // we are done with this CSet.
2030 ergo_verbose4(ErgoCSetConstruction,
2031 "finish adding old regions to CSet",
2032 ergo_format_reason("predicted time is too high")
2033 ergo_format_ms("predicted time")
2034 ergo_format_ms("remaining time")
2035 ergo_format_region("old")
2036 ergo_format_region("min"),
2037 predicted_time_ms, time_remaining_ms,
2038 old_cset_region_length(), min_old_cset_length);
2039 break;
2040 }
2041
2042 // We'll add it anyway given that we haven't reached the
2043 // minimum number of old regions.
2044 expensive_region_num += 1;
2045 }
2046 } else {
2047 if (old_cset_region_length() >= min_old_cset_length) {
2048 // In the non-auto-tuning case, we'll finish adding regions
2049 // to the CSet if we reach the minimum.
2050 ergo_verbose2(ErgoCSetConstruction,
2051 "finish adding old regions to CSet",
2052 ergo_format_reason("old CSet region num reached min")
2053 ergo_format_region("old")
2054 ergo_format_region("min"),
2055 old_cset_region_length(), min_old_cset_length);
2056 break;
2057 }
2058 }
2059
2060 // We will add this region to the CSet.
2061 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2062 predicted_pause_time_ms += predicted_time_ms;
2063 cset_chooser->remove_and_move_to_next(hr);
2064 _g1->old_set_remove(hr);
2065 add_old_region_to_cset(hr);
2066
2067 hr = cset_chooser->peek();
2068 }
2069 if (hr == NULL) {
2070 ergo_verbose0(ErgoCSetConstruction,
2071 "finish adding old regions to CSet",
2072 ergo_format_reason("candidate old regions not available"));
2073 }
2074
2075 if (expensive_region_num > 0) {
2076 // We print the information once here at the end, predicated on
2077 // whether we added any apparently expensive regions or not, to
2078 // avoid generating output per region.
2079 ergo_verbose4(ErgoCSetConstruction,
2080 "added expensive regions to CSet",
2081 ergo_format_reason("old CSet region num not reached min")
2082 ergo_format_region("old")
2083 ergo_format_region("expensive")
2084 ergo_format_region("min")
2085 ergo_format_ms("remaining time"),
2086 old_cset_region_length(),
2087 expensive_region_num,
2088 min_old_cset_length,
2089 time_remaining_ms);
2090 }
2091
2092 cset_chooser->verify();
2093 }
2094
2095 stop_incremental_cset_building();
2096
2097 ergo_verbose5(ErgoCSetConstruction,
2098 "finish choosing CSet",
2099 ergo_format_region("eden")
2100 ergo_format_region("survivors")
2101 ergo_format_region("old")
2102 ergo_format_ms("predicted pause time")
2103 ergo_format_ms("target pause time"),
2104 eden_region_length, survivor_region_length,
2105 old_cset_region_length(),
2106 predicted_pause_time_ms, target_pause_time_ms);
2107
2108 double non_young_end_time_sec = os::elapsedTime();
2109 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2110 evacuation_info.set_collectionset_regions(cset_region_length());
2111 }
2112
2113 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2114 if(TraceGen0Time) {
2115 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2116 }
2117 }
2118
2119 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2120 if(TraceGen0Time) {
2121 _all_yield_times_ms.add(yield_time_ms);
2122 }
2123 }
2124
2125 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2126 if(TraceGen0Time) {
2127 _total.add(pause_time_ms);
2128 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2129 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2130 _parallel.add(phase_times->cur_collection_par_time_ms());
2131 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2132 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2133 _update_rs.add(phase_times->average_last_update_rs_time());
2134 _scan_rs.add(phase_times->average_last_scan_rs_time());
2135 _obj_copy.add(phase_times->average_last_obj_copy_time());
2136 _termination.add(phase_times->average_last_termination_time());
2137
2138 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2139 phase_times->average_last_satb_filtering_times_ms() +
2140 phase_times->average_last_update_rs_time() +
2141 phase_times->average_last_scan_rs_time() +
2142 phase_times->average_last_obj_copy_time() +
2143 + phase_times->average_last_termination_time();
2144
2145 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2146 _parallel_other.add(parallel_other_time);
2147 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2148 }
2149 }
2150
2151 void TraceGen0TimeData::increment_young_collection_count() {
2152 if(TraceGen0Time) {
2153 ++_young_pause_num;
2154 }
2155 }
2156
2157 void TraceGen0TimeData::increment_mixed_collection_count() {
2158 if(TraceGen0Time) {
2159 ++_mixed_pause_num;
2160 }
2161 }
2162
2163 void TraceGen0TimeData::print_summary(const char* str,
2164 const NumberSeq* seq) const {
2165 double sum = seq->sum();
2166 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2167 str, sum / 1000.0, seq->avg());
2168 }
2169
2170 void TraceGen0TimeData::print_summary_sd(const char* str,
2171 const NumberSeq* seq) const {
2172 print_summary(str, seq);
2173 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2174 "(num", seq->num(), seq->sd(), seq->maximum());
2175 }
2176
2177 void TraceGen0TimeData::print() const {
2178 if (!TraceGen0Time) {
2179 return;
2180 }
2181
2182 gclog_or_tty->print_cr("ALL PAUSES");
2183 print_summary_sd(" Total", &_total);
2184 gclog_or_tty->print_cr("");
2185 gclog_or_tty->print_cr("");
2186 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2187 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2188 gclog_or_tty->print_cr("");
2189
2190 gclog_or_tty->print_cr("EVACUATION PAUSES");
2191
2192 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2193 gclog_or_tty->print_cr("none");
2194 } else {
2195 print_summary_sd(" Evacuation Pauses", &_total);
2196 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2197 print_summary(" Parallel Time", &_parallel);
2198 print_summary(" Ext Root Scanning", &_ext_root_scan);
2199 print_summary(" SATB Filtering", &_satb_filtering);
2200 print_summary(" Update RS", &_update_rs);
2201 print_summary(" Scan RS", &_scan_rs);
2202 print_summary(" Object Copy", &_obj_copy);
2203 print_summary(" Termination", &_termination);
2204 print_summary(" Parallel Other", &_parallel_other);
2205 print_summary(" Clear CT", &_clear_ct);
2206 print_summary(" Other", &_other);
2207 }
2208 gclog_or_tty->print_cr("");
2209
2210 gclog_or_tty->print_cr("MISC");
2211 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2212 print_summary_sd(" Yields", &_all_yield_times_ms);
2213 }
2214
2215 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2216 if (TraceGen1Time) {
2217 _all_full_gc_times.add(full_gc_time_ms);
2218 }
2219 }
2220
2221 void TraceGen1TimeData::print() const {
2222 if (!TraceGen1Time) {
2223 return;
2224 }
2225
2226 if (_all_full_gc_times.num() > 0) {
2227 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2228 _all_full_gc_times.num(),
2229 _all_full_gc_times.sum() / 1000.0);
2230 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2231 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2232 _all_full_gc_times.sd(),
2233 _all_full_gc_times.maximum());
2234 }
2235 }