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 size_t card_table_alignment = GenRemSet::max_alignment_constraint(rem_set_name());
313 set_max_alignment(MAX2(card_table_alignment, min_alignment()));
314 if (SurvivorRatio < 1) {
315 vm_exit_during_initialization("Invalid survivor ratio specified");
316 }
317 CollectorPolicy::initialize_flags();
318 }
319
320 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
321 assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max");
322 assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds");
323 assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds");
324
325 if (FLAG_IS_CMDLINE(NewRatio)) {
326 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
327 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
328 } else {
329 _sizer_kind = SizerNewRatio;
330 _adaptive_size = false;
331 return;
332 }
333 }
334
335 if (FLAG_IS_CMDLINE(NewSize)) {
336 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
337 1U);
338 if (FLAG_IS_CMDLINE(MaxNewSize)) {
339 _max_desired_young_length =
340 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
341 1U);
342 _sizer_kind = SizerMaxAndNewSize;
343 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
344 } else {
345 _sizer_kind = SizerNewSizeOnly;
346 }
347 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
348 _max_desired_young_length =
349 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
350 1U);
351 _sizer_kind = SizerMaxNewSizeOnly;
352 }
353 }
354
355 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
356 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
357 return MAX2(1U, default_value);
358 }
359
360 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
361 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
362 return MAX2(1U, default_value);
363 }
364
365 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
366 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
367
368 switch (_sizer_kind) {
369 case SizerDefaults:
370 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
371 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
372 break;
373 case SizerNewSizeOnly:
374 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
375 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
376 break;
377 case SizerMaxNewSizeOnly:
378 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
379 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
380 break;
381 case SizerMaxAndNewSize:
382 // Do nothing. Values set on the command line, don't update them at runtime.
383 break;
384 case SizerNewRatio:
385 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
386 _max_desired_young_length = _min_desired_young_length;
387 break;
388 default:
389 ShouldNotReachHere();
390 }
391
392 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
393 }
394
395 void G1CollectorPolicy::init() {
396 // Set aside an initial future to_space.
397 _g1 = G1CollectedHeap::heap();
398
399 assert(Heap_lock->owned_by_self(), "Locking discipline.");
400
401 initialize_gc_policy_counters();
402
403 if (adaptive_young_list_length()) {
404 _young_list_fixed_length = 0;
405 } else {
406 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
407 }
408 _free_regions_at_end_of_collection = _g1->free_regions();
409 update_young_list_target_length();
410
411 // We may immediately start allocating regions and placing them on the
412 // collection set list. Initialize the per-collection set info
413 start_incremental_cset_building();
414 }
415
416 // Create the jstat counters for the policy.
417 void G1CollectorPolicy::initialize_gc_policy_counters() {
418 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
419 }
420
421 bool G1CollectorPolicy::predict_will_fit(uint young_length,
422 double base_time_ms,
423 uint base_free_regions,
424 double target_pause_time_ms) {
425 if (young_length >= base_free_regions) {
426 // end condition 1: not enough space for the young regions
427 return false;
428 }
429
430 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
431 size_t bytes_to_copy =
432 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
433 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
434 double young_other_time_ms = predict_young_other_time_ms(young_length);
435 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
436 if (pause_time_ms > target_pause_time_ms) {
437 // end condition 2: prediction is over the target pause time
438 return false;
439 }
440
441 size_t free_bytes =
442 (base_free_regions - young_length) * HeapRegion::GrainBytes;
443 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
444 // end condition 3: out-of-space (conservatively!)
445 return false;
446 }
447
448 // success!
449 return true;
450 }
451
452 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
453 // re-calculate the necessary reserve
454 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
455 // We use ceiling so that if reserve_regions_d is > 0.0 (but
456 // smaller than 1.0) we'll get 1.
457 _reserve_regions = (uint) ceil(reserve_regions_d);
458
459 _young_gen_sizer->heap_size_changed(new_number_of_regions);
460 }
461
462 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
463 uint base_min_length) {
464 uint desired_min_length = 0;
465 if (adaptive_young_list_length()) {
466 if (_alloc_rate_ms_seq->num() > 3) {
467 double now_sec = os::elapsedTime();
468 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
469 double alloc_rate_ms = predict_alloc_rate_ms();
470 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
471 } else {
472 // otherwise we don't have enough info to make the prediction
473 }
474 }
475 desired_min_length += base_min_length;
476 // make sure we don't go below any user-defined minimum bound
477 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
478 }
479
480 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
481 // Here, we might want to also take into account any additional
482 // constraints (i.e., user-defined minimum bound). Currently, we
483 // effectively don't set this bound.
484 return _young_gen_sizer->max_desired_young_length();
485 }
486
487 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
488 if (rs_lengths == (size_t) -1) {
489 // if it's set to the default value (-1), we should predict it;
490 // otherwise, use the given value.
491 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
492 }
493
494 // Calculate the absolute and desired min bounds.
495
496 // This is how many young regions we already have (currently: the survivors).
497 uint base_min_length = recorded_survivor_regions();
498 // This is the absolute minimum young length, which ensures that we
499 // can allocate one eden region in the worst-case.
500 uint absolute_min_length = base_min_length + 1;
501 uint desired_min_length =
502 calculate_young_list_desired_min_length(base_min_length);
503 if (desired_min_length < absolute_min_length) {
504 desired_min_length = absolute_min_length;
505 }
506
507 // Calculate the absolute and desired max bounds.
508
509 // We will try our best not to "eat" into the reserve.
510 uint absolute_max_length = 0;
511 if (_free_regions_at_end_of_collection > _reserve_regions) {
512 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
513 }
514 uint desired_max_length = calculate_young_list_desired_max_length();
515 if (desired_max_length > absolute_max_length) {
516 desired_max_length = absolute_max_length;
517 }
518
519 uint young_list_target_length = 0;
520 if (adaptive_young_list_length()) {
521 if (gcs_are_young()) {
522 young_list_target_length =
523 calculate_young_list_target_length(rs_lengths,
524 base_min_length,
525 desired_min_length,
526 desired_max_length);
527 _rs_lengths_prediction = rs_lengths;
528 } else {
529 // Don't calculate anything and let the code below bound it to
530 // the desired_min_length, i.e., do the next GC as soon as
531 // possible to maximize how many old regions we can add to it.
532 }
533 } else {
534 // The user asked for a fixed young gen so we'll fix the young gen
535 // whether the next GC is young or mixed.
536 young_list_target_length = _young_list_fixed_length;
537 }
538
539 // Make sure we don't go over the desired max length, nor under the
540 // desired min length. In case they clash, desired_min_length wins
541 // which is why that test is second.
542 if (young_list_target_length > desired_max_length) {
543 young_list_target_length = desired_max_length;
544 }
545 if (young_list_target_length < desired_min_length) {
546 young_list_target_length = desired_min_length;
547 }
548
549 assert(young_list_target_length > recorded_survivor_regions(),
550 "we should be able to allocate at least one eden region");
551 assert(young_list_target_length >= absolute_min_length, "post-condition");
552 _young_list_target_length = young_list_target_length;
553
554 update_max_gc_locker_expansion();
555 }
556
557 uint
558 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
559 uint base_min_length,
560 uint desired_min_length,
561 uint desired_max_length) {
562 assert(adaptive_young_list_length(), "pre-condition");
563 assert(gcs_are_young(), "only call this for young GCs");
564
565 // In case some edge-condition makes the desired max length too small...
566 if (desired_max_length <= desired_min_length) {
567 return desired_min_length;
568 }
569
570 // We'll adjust min_young_length and max_young_length not to include
571 // the already allocated young regions (i.e., so they reflect the
572 // min and max eden regions we'll allocate). The base_min_length
573 // will be reflected in the predictions by the
574 // survivor_regions_evac_time prediction.
575 assert(desired_min_length > base_min_length, "invariant");
576 uint min_young_length = desired_min_length - base_min_length;
577 assert(desired_max_length > base_min_length, "invariant");
578 uint max_young_length = desired_max_length - base_min_length;
579
580 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
581 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
582 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
583 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
584 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
585 double base_time_ms =
586 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
587 survivor_regions_evac_time;
588 uint available_free_regions = _free_regions_at_end_of_collection;
589 uint base_free_regions = 0;
590 if (available_free_regions > _reserve_regions) {
591 base_free_regions = available_free_regions - _reserve_regions;
592 }
593
594 // Here, we will make sure that the shortest young length that
595 // makes sense fits within the target pause time.
596
597 if (predict_will_fit(min_young_length, base_time_ms,
598 base_free_regions, target_pause_time_ms)) {
599 // The shortest young length will fit into the target pause time;
600 // we'll now check whether the absolute maximum number of young
601 // regions will fit in the target pause time. If not, we'll do
602 // a binary search between min_young_length and max_young_length.
603 if (predict_will_fit(max_young_length, base_time_ms,
604 base_free_regions, target_pause_time_ms)) {
605 // The maximum young length will fit into the target pause time.
606 // We are done so set min young length to the maximum length (as
607 // the result is assumed to be returned in min_young_length).
608 min_young_length = max_young_length;
609 } else {
610 // The maximum possible number of young regions will not fit within
611 // the target pause time so we'll search for the optimal
612 // length. The loop invariants are:
613 //
614 // min_young_length < max_young_length
615 // min_young_length is known to fit into the target pause time
616 // max_young_length is known not to fit into the target pause time
617 //
618 // Going into the loop we know the above hold as we've just
619 // checked them. Every time around the loop we check whether
620 // the middle value between min_young_length and
621 // max_young_length fits into the target pause time. If it
622 // does, it becomes the new min. If it doesn't, it becomes
623 // the new max. This way we maintain the loop invariants.
624
625 assert(min_young_length < max_young_length, "invariant");
626 uint diff = (max_young_length - min_young_length) / 2;
627 while (diff > 0) {
628 uint young_length = min_young_length + diff;
629 if (predict_will_fit(young_length, base_time_ms,
630 base_free_regions, target_pause_time_ms)) {
631 min_young_length = young_length;
632 } else {
633 max_young_length = young_length;
634 }
635 assert(min_young_length < max_young_length, "invariant");
636 diff = (max_young_length - min_young_length) / 2;
637 }
638 // The results is min_young_length which, according to the
639 // loop invariants, should fit within the target pause time.
640
641 // These are the post-conditions of the binary search above:
642 assert(min_young_length < max_young_length,
643 "otherwise we should have discovered that max_young_length "
644 "fits into the pause target and not done the binary search");
645 assert(predict_will_fit(min_young_length, base_time_ms,
646 base_free_regions, target_pause_time_ms),
647 "min_young_length, the result of the binary search, should "
648 "fit into the pause target");
649 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
650 base_free_regions, target_pause_time_ms),
651 "min_young_length, the result of the binary search, should be "
652 "optimal, so no larger length should fit into the pause target");
653 }
654 } else {
655 // Even the minimum length doesn't fit into the pause time
656 // target, return it as the result nevertheless.
657 }
658 return base_min_length + min_young_length;
659 }
660
661 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
662 double survivor_regions_evac_time = 0.0;
663 for (HeapRegion * r = _recorded_survivor_head;
664 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
665 r = r->get_next_young_region()) {
666 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
667 }
668 return survivor_regions_evac_time;
669 }
670
671 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
672 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
673
674 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
675 if (rs_lengths > _rs_lengths_prediction) {
676 // add 10% to avoid having to recalculate often
677 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
678 update_young_list_target_length(rs_lengths_prediction);
679 }
680 }
681
682
683
684 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
685 bool is_tlab,
686 bool* gc_overhead_limit_was_exceeded) {
687 guarantee(false, "Not using this policy feature yet.");
688 return NULL;
689 }
690
691 // This method controls how a collector handles one or more
692 // of its generations being fully allocated.
693 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
694 bool is_tlab) {
695 guarantee(false, "Not using this policy feature yet.");
696 return NULL;
697 }
698
699
700 #ifndef PRODUCT
701 bool G1CollectorPolicy::verify_young_ages() {
702 HeapRegion* head = _g1->young_list()->first_region();
703 return
704 verify_young_ages(head, _short_lived_surv_rate_group);
705 // also call verify_young_ages on any additional surv rate groups
706 }
707
708 bool
709 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
710 SurvRateGroup *surv_rate_group) {
711 guarantee( surv_rate_group != NULL, "pre-condition" );
712
713 const char* name = surv_rate_group->name();
714 bool ret = true;
715 int prev_age = -1;
716
717 for (HeapRegion* curr = head;
718 curr != NULL;
719 curr = curr->get_next_young_region()) {
720 SurvRateGroup* group = curr->surv_rate_group();
721 if (group == NULL && !curr->is_survivor()) {
722 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
723 ret = false;
724 }
725
726 if (surv_rate_group == group) {
727 int age = curr->age_in_surv_rate_group();
728
729 if (age < 0) {
730 gclog_or_tty->print_cr("## %s: encountered negative age", name);
731 ret = false;
732 }
733
734 if (age <= prev_age) {
735 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
736 "(%d, %d)", name, age, prev_age);
737 ret = false;
738 }
739 prev_age = age;
740 }
741 }
742
743 return ret;
744 }
745 #endif // PRODUCT
746
747 void G1CollectorPolicy::record_full_collection_start() {
748 _full_collection_start_sec = os::elapsedTime();
749 record_heap_size_info_at_start();
750 // Release the future to-space so that it is available for compaction into.
751 _g1->set_full_collection();
752 }
753
754 void G1CollectorPolicy::record_full_collection_end() {
755 // Consider this like a collection pause for the purposes of allocation
756 // since last pause.
757 double end_sec = os::elapsedTime();
758 double full_gc_time_sec = end_sec - _full_collection_start_sec;
759 double full_gc_time_ms = full_gc_time_sec * 1000.0;
760
761 _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
762
763 update_recent_gc_times(end_sec, full_gc_time_ms);
764
765 _g1->clear_full_collection();
766
767 // "Nuke" the heuristics that control the young/mixed GC
768 // transitions and make sure we start with young GCs after the Full GC.
769 set_gcs_are_young(true);
770 _last_young_gc = false;
771 clear_initiate_conc_mark_if_possible();
772 clear_during_initial_mark_pause();
773 _in_marking_window = false;
774 _in_marking_window_im = false;
775
776 _short_lived_surv_rate_group->start_adding_regions();
777 // also call this on any additional surv rate groups
778
779 record_survivor_regions(0, NULL, NULL);
780
781 _free_regions_at_end_of_collection = _g1->free_regions();
782 // Reset survivors SurvRateGroup.
783 _survivor_surv_rate_group->reset();
784 update_young_list_target_length();
785 _collectionSetChooser->clear();
786 }
787
788 void G1CollectorPolicy::record_stop_world_start() {
789 _stop_world_start = os::elapsedTime();
790 }
791
792 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
793 // We only need to do this here as the policy will only be applied
794 // to the GC we're about to start. so, no point is calculating this
795 // every time we calculate / recalculate the target young length.
796 update_survivors_policy();
797
798 assert(_g1->used() == _g1->recalculate_used(),
799 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
800 _g1->used(), _g1->recalculate_used()));
801
802 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
803 _trace_gen0_time_data.record_start_collection(s_w_t_ms);
804 _stop_world_start = 0.0;
805
806 record_heap_size_info_at_start();
807
808 phase_times()->record_cur_collection_start_sec(start_time_sec);
809 _pending_cards = _g1->pending_card_num();
810
811 _collection_set_bytes_used_before = 0;
812 _bytes_copied_during_gc = 0;
813
814 _last_gc_was_young = false;
815
816 // do that for any other surv rate groups
817 _short_lived_surv_rate_group->stop_adding_regions();
818 _survivors_age_table.clear();
819
820 assert( verify_young_ages(), "region age verification" );
821 }
822
823 void G1CollectorPolicy::record_concurrent_mark_init_end(double
824 mark_init_elapsed_time_ms) {
825 _during_marking = true;
826 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
827 clear_during_initial_mark_pause();
828 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
829 }
830
831 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
832 _mark_remark_start_sec = os::elapsedTime();
833 _during_marking = false;
834 }
835
836 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
837 double end_time_sec = os::elapsedTime();
838 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
839 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
840 _cur_mark_stop_world_time_ms += elapsed_time_ms;
841 _prev_collection_pause_end_ms += elapsed_time_ms;
842
843 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
844 }
845
846 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
847 _mark_cleanup_start_sec = os::elapsedTime();
848 }
849
850 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
851 _last_young_gc = true;
852 _in_marking_window = false;
853 }
854
855 void G1CollectorPolicy::record_concurrent_pause() {
856 if (_stop_world_start > 0.0) {
857 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
858 _trace_gen0_time_data.record_yield_time(yield_ms);
859 }
860 }
861
862 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
863 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
864 return false;
865 }
866
867 size_t marking_initiating_used_threshold =
868 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
869 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
870 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
871
872 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
873 if (gcs_are_young()) {
874 ergo_verbose5(ErgoConcCycles,
875 "request concurrent cycle initiation",
876 ergo_format_reason("occupancy higher than threshold")
877 ergo_format_byte("occupancy")
878 ergo_format_byte("allocation request")
879 ergo_format_byte_perc("threshold")
880 ergo_format_str("source"),
881 cur_used_bytes,
882 alloc_byte_size,
883 marking_initiating_used_threshold,
884 (double) InitiatingHeapOccupancyPercent,
885 source);
886 return true;
887 } else {
888 ergo_verbose5(ErgoConcCycles,
889 "do not request concurrent cycle initiation",
890 ergo_format_reason("still doing mixed collections")
891 ergo_format_byte("occupancy")
892 ergo_format_byte("allocation request")
893 ergo_format_byte_perc("threshold")
894 ergo_format_str("source"),
895 cur_used_bytes,
896 alloc_byte_size,
897 marking_initiating_used_threshold,
898 (double) InitiatingHeapOccupancyPercent,
899 source);
900 }
901 }
902
903 return false;
904 }
905
906 // Anything below that is considered to be zero
907 #define MIN_TIMER_GRANULARITY 0.0000001
908
909 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
910 double end_time_sec = os::elapsedTime();
911 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
912 "otherwise, the subtraction below does not make sense");
913 size_t rs_size =
914 _cur_collection_pause_used_regions_at_start - cset_region_length();
915 size_t cur_used_bytes = _g1->used();
916 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
917 bool last_pause_included_initial_mark = false;
918 bool update_stats = !_g1->evacuation_failed();
919
920 #ifndef PRODUCT
921 if (G1YoungSurvRateVerbose) {
922 gclog_or_tty->print_cr("");
923 _short_lived_surv_rate_group->print();
924 // do that for any other surv rate groups too
925 }
926 #endif // PRODUCT
927
928 last_pause_included_initial_mark = during_initial_mark_pause();
929 if (last_pause_included_initial_mark) {
930 record_concurrent_mark_init_end(0.0);
931 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
932 // Note: this might have already been set, if during the last
933 // pause we decided to start a cycle but at the beginning of
934 // this pause we decided to postpone it. That's OK.
935 set_initiate_conc_mark_if_possible();
936 }
937
938 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
939 end_time_sec, false);
940
941 size_t freed_bytes =
942 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
943 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
944
945 double survival_fraction =
946 (double)surviving_bytes/
947 (double)_collection_set_bytes_used_before;
948
949 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
950 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
951
952 if (update_stats) {
953 _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
954 // this is where we update the allocation rate of the application
955 double app_time_ms =
956 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
957 if (app_time_ms < MIN_TIMER_GRANULARITY) {
958 // This usually happens due to the timer not having the required
959 // granularity. Some Linuxes are the usual culprits.
960 // We'll just set it to something (arbitrarily) small.
961 app_time_ms = 1.0;
962 }
963 // We maintain the invariant that all objects allocated by mutator
964 // threads will be allocated out of eden regions. So, we can use
965 // the eden region number allocated since the previous GC to
966 // calculate the application's allocate rate. The only exception
967 // to that is humongous objects that are allocated separately. But
968 // given that humongous object allocations do not really affect
969 // either the pause's duration nor when the next pause will take
970 // place we can safely ignore them here.
971 uint regions_allocated = eden_cset_region_length();
972 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
973 _alloc_rate_ms_seq->add(alloc_rate_ms);
974
975 double interval_ms =
976 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
977 update_recent_gc_times(end_time_sec, pause_time_ms);
978 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
979 if (recent_avg_pause_time_ratio() < 0.0 ||
980 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
981 #ifndef PRODUCT
982 // Dump info to allow post-facto debugging
983 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
984 gclog_or_tty->print_cr("-------------------------------------------");
985 gclog_or_tty->print_cr("Recent GC Times (ms):");
986 _recent_gc_times_ms->dump();
987 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
988 _recent_prev_end_times_for_all_gcs_sec->dump();
989 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
990 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
991 // In debug mode, terminate the JVM if the user wants to debug at this point.
992 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
993 #endif // !PRODUCT
994 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
995 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
996 if (_recent_avg_pause_time_ratio < 0.0) {
997 _recent_avg_pause_time_ratio = 0.0;
998 } else {
999 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1000 _recent_avg_pause_time_ratio = 1.0;
1001 }
1002 }
1003 }
1004 bool new_in_marking_window = _in_marking_window;
1005 bool new_in_marking_window_im = false;
1006 if (during_initial_mark_pause()) {
1007 new_in_marking_window = true;
1008 new_in_marking_window_im = true;
1009 }
1010
1011 if (_last_young_gc) {
1012 // This is supposed to to be the "last young GC" before we start
1013 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1014
1015 if (!last_pause_included_initial_mark) {
1016 if (next_gc_should_be_mixed("start mixed GCs",
1017 "do not start mixed GCs")) {
1018 set_gcs_are_young(false);
1019 }
1020 } else {
1021 ergo_verbose0(ErgoMixedGCs,
1022 "do not start mixed GCs",
1023 ergo_format_reason("concurrent cycle is about to start"));
1024 }
1025 _last_young_gc = false;
1026 }
1027
1028 if (!_last_gc_was_young) {
1029 // This is a mixed GC. Here we decide whether to continue doing
1030 // mixed GCs or not.
1031
1032 if (!next_gc_should_be_mixed("continue mixed GCs",
1033 "do not continue mixed GCs")) {
1034 set_gcs_are_young(true);
1035 }
1036 }
1037
1038 _short_lived_surv_rate_group->start_adding_regions();
1039 // do that for any other surv rate groupsx
1040
1041 if (update_stats) {
1042 double cost_per_card_ms = 0.0;
1043 if (_pending_cards > 0) {
1044 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1045 _cost_per_card_ms_seq->add(cost_per_card_ms);
1046 }
1047
1048 size_t cards_scanned = _g1->cards_scanned();
1049
1050 double cost_per_entry_ms = 0.0;
1051 if (cards_scanned > 10) {
1052 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1053 if (_last_gc_was_young) {
1054 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1055 } else {
1056 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1057 }
1058 }
1059
1060 if (_max_rs_lengths > 0) {
1061 double cards_per_entry_ratio =
1062 (double) cards_scanned / (double) _max_rs_lengths;
1063 if (_last_gc_was_young) {
1064 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1065 } else {
1066 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1067 }
1068 }
1069
1070 // This is defensive. For a while _max_rs_lengths could get
1071 // smaller than _recorded_rs_lengths which was causing
1072 // rs_length_diff to get very large and mess up the RSet length
1073 // predictions. The reason was unsafe concurrent updates to the
1074 // _inc_cset_recorded_rs_lengths field which the code below guards
1075 // against (see CR 7118202). This bug has now been fixed (see CR
1076 // 7119027). However, I'm still worried that
1077 // _inc_cset_recorded_rs_lengths might still end up somewhat
1078 // inaccurate. The concurrent refinement thread calculates an
1079 // RSet's length concurrently with other CR threads updating it
1080 // which might cause it to calculate the length incorrectly (if,
1081 // say, it's in mid-coarsening). So I'll leave in the defensive
1082 // conditional below just in case.
1083 size_t rs_length_diff = 0;
1084 if (_max_rs_lengths > _recorded_rs_lengths) {
1085 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1086 }
1087 _rs_length_diff_seq->add((double) rs_length_diff);
1088
1089 size_t copied_bytes = surviving_bytes;
1090 double cost_per_byte_ms = 0.0;
1091 if (copied_bytes > 0) {
1092 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1093 if (_in_marking_window) {
1094 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1095 } else {
1096 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1097 }
1098 }
1099
1100 double all_other_time_ms = pause_time_ms -
1101 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1102 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1103
1104 double young_other_time_ms = 0.0;
1105 if (young_cset_region_length() > 0) {
1106 young_other_time_ms =
1107 phase_times()->young_cset_choice_time_ms() +
1108 phase_times()->young_free_cset_time_ms();
1109 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1110 (double) young_cset_region_length());
1111 }
1112 double non_young_other_time_ms = 0.0;
1113 if (old_cset_region_length() > 0) {
1114 non_young_other_time_ms =
1115 phase_times()->non_young_cset_choice_time_ms() +
1116 phase_times()->non_young_free_cset_time_ms();
1117
1118 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1119 (double) old_cset_region_length());
1120 }
1121
1122 double constant_other_time_ms = all_other_time_ms -
1123 (young_other_time_ms + non_young_other_time_ms);
1124 _constant_other_time_ms_seq->add(constant_other_time_ms);
1125
1126 double survival_ratio = 0.0;
1127 if (_collection_set_bytes_used_before > 0) {
1128 survival_ratio = (double) _bytes_copied_during_gc /
1129 (double) _collection_set_bytes_used_before;
1130 }
1131
1132 _pending_cards_seq->add((double) _pending_cards);
1133 _rs_lengths_seq->add((double) _max_rs_lengths);
1134 }
1135
1136 _in_marking_window = new_in_marking_window;
1137 _in_marking_window_im = new_in_marking_window_im;
1138 _free_regions_at_end_of_collection = _g1->free_regions();
1139 update_young_list_target_length();
1140
1141 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1142 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1143 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1144 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1145
1146 _collectionSetChooser->verify();
1147 }
1148
1149 #define EXT_SIZE_FORMAT "%.1f%s"
1150 #define EXT_SIZE_PARAMS(bytes) \
1151 byte_size_in_proper_unit((double)(bytes)), \
1152 proper_unit_for_byte_size((bytes))
1153
1154 void G1CollectorPolicy::record_heap_size_info_at_start() {
1155 YoungList* young_list = _g1->young_list();
1156 _eden_bytes_before_gc = young_list->eden_used_bytes();
1157 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
1158 _capacity_before_gc = _g1->capacity();
1159
1160 _cur_collection_pause_used_at_start_bytes = _g1->used();
1161 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
1162
1163 size_t eden_capacity_before_gc =
1164 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_bytes_before_gc;
1165
1166 _prev_eden_capacity = eden_capacity_before_gc;
1167 }
1168
1169 void G1CollectorPolicy::print_heap_transition() {
1170 _g1->print_size_transition(gclog_or_tty,
1171 _cur_collection_pause_used_at_start_bytes, _g1->used(), _g1->capacity());
1172 }
1173
1174 void G1CollectorPolicy::print_detailed_heap_transition() {
1175 YoungList* young_list = _g1->young_list();
1176 size_t eden_bytes = young_list->eden_used_bytes();
1177 size_t survivor_bytes = young_list->survivor_used_bytes();
1178 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1179 size_t used = _g1->used();
1180 size_t capacity = _g1->capacity();
1181 size_t eden_capacity =
1182 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1183
1184 gclog_or_tty->print_cr(
1185 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1186 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1187 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1188 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1189 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1190 EXT_SIZE_PARAMS(_prev_eden_capacity),
1191 EXT_SIZE_PARAMS(eden_bytes),
1192 EXT_SIZE_PARAMS(eden_capacity),
1193 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1194 EXT_SIZE_PARAMS(survivor_bytes),
1195 EXT_SIZE_PARAMS(used_before_gc),
1196 EXT_SIZE_PARAMS(_capacity_before_gc),
1197 EXT_SIZE_PARAMS(used),
1198 EXT_SIZE_PARAMS(capacity));
1199 }
1200
1201 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1202 double update_rs_processed_buffers,
1203 double goal_ms) {
1204 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1205 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1206
1207 if (G1UseAdaptiveConcRefinement) {
1208 const int k_gy = 3, k_gr = 6;
1209 const double inc_k = 1.1, dec_k = 0.9;
1210
1211 int g = cg1r->green_zone();
1212 if (update_rs_time > goal_ms) {
1213 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1214 } else {
1215 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1216 g = (int)MAX2(g * inc_k, g + 1.0);
1217 }
1218 }
1219 // Change the refinement threads params
1220 cg1r->set_green_zone(g);
1221 cg1r->set_yellow_zone(g * k_gy);
1222 cg1r->set_red_zone(g * k_gr);
1223 cg1r->reinitialize_threads();
1224
1225 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1226 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1227 cg1r->yellow_zone());
1228 // Change the barrier params
1229 dcqs.set_process_completed_threshold(processing_threshold);
1230 dcqs.set_max_completed_queue(cg1r->red_zone());
1231 }
1232
1233 int curr_queue_size = dcqs.completed_buffers_num();
1234 if (curr_queue_size >= cg1r->yellow_zone()) {
1235 dcqs.set_completed_queue_padding(curr_queue_size);
1236 } else {
1237 dcqs.set_completed_queue_padding(0);
1238 }
1239 dcqs.notify_if_necessary();
1240 }
1241
1242 double
1243 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1244 size_t scanned_cards) {
1245 return
1246 predict_rs_update_time_ms(pending_cards) +
1247 predict_rs_scan_time_ms(scanned_cards) +
1248 predict_constant_other_time_ms();
1249 }
1250
1251 double
1252 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1253 size_t rs_length = predict_rs_length_diff();
1254 size_t card_num;
1255 if (gcs_are_young()) {
1256 card_num = predict_young_card_num(rs_length);
1257 } else {
1258 card_num = predict_non_young_card_num(rs_length);
1259 }
1260 return predict_base_elapsed_time_ms(pending_cards, card_num);
1261 }
1262
1263 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1264 size_t bytes_to_copy;
1265 if (hr->is_marked())
1266 bytes_to_copy = hr->max_live_bytes();
1267 else {
1268 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1269 int age = hr->age_in_surv_rate_group();
1270 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1271 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1272 }
1273 return bytes_to_copy;
1274 }
1275
1276 double
1277 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1278 bool for_young_gc) {
1279 size_t rs_length = hr->rem_set()->occupied();
1280 size_t card_num;
1281
1282 // Predicting the number of cards is based on which type of GC
1283 // we're predicting for.
1284 if (for_young_gc) {
1285 card_num = predict_young_card_num(rs_length);
1286 } else {
1287 card_num = predict_non_young_card_num(rs_length);
1288 }
1289 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1290
1291 double region_elapsed_time_ms =
1292 predict_rs_scan_time_ms(card_num) +
1293 predict_object_copy_time_ms(bytes_to_copy);
1294
1295 // The prediction of the "other" time for this region is based
1296 // upon the region type and NOT the GC type.
1297 if (hr->is_young()) {
1298 region_elapsed_time_ms += predict_young_other_time_ms(1);
1299 } else {
1300 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1301 }
1302 return region_elapsed_time_ms;
1303 }
1304
1305 void
1306 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1307 uint survivor_cset_region_length) {
1308 _eden_cset_region_length = eden_cset_region_length;
1309 _survivor_cset_region_length = survivor_cset_region_length;
1310 _old_cset_region_length = 0;
1311 }
1312
1313 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1314 _recorded_rs_lengths = rs_lengths;
1315 }
1316
1317 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1318 double elapsed_ms) {
1319 _recent_gc_times_ms->add(elapsed_ms);
1320 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1321 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1322 }
1323
1324 size_t G1CollectorPolicy::expansion_amount() {
1325 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1326 double threshold = _gc_overhead_perc;
1327 if (recent_gc_overhead > threshold) {
1328 // We will double the existing space, or take
1329 // G1ExpandByPercentOfAvailable % of the available expansion
1330 // space, whichever is smaller, bounded below by a minimum
1331 // expansion (unless that's all that's left.)
1332 const size_t min_expand_bytes = 1*M;
1333 size_t reserved_bytes = _g1->max_capacity();
1334 size_t committed_bytes = _g1->capacity();
1335 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1336 size_t expand_bytes;
1337 size_t expand_bytes_via_pct =
1338 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1339 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1340 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1341 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1342
1343 ergo_verbose5(ErgoHeapSizing,
1344 "attempt heap expansion",
1345 ergo_format_reason("recent GC overhead higher than "
1346 "threshold after GC")
1347 ergo_format_perc("recent GC overhead")
1348 ergo_format_perc("threshold")
1349 ergo_format_byte("uncommitted")
1350 ergo_format_byte_perc("calculated expansion amount"),
1351 recent_gc_overhead, threshold,
1352 uncommitted_bytes,
1353 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1354
1355 return expand_bytes;
1356 } else {
1357 return 0;
1358 }
1359 }
1360
1361 void G1CollectorPolicy::print_tracing_info() const {
1362 _trace_gen0_time_data.print();
1363 _trace_gen1_time_data.print();
1364 }
1365
1366 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1367 #ifndef PRODUCT
1368 _short_lived_surv_rate_group->print_surv_rate_summary();
1369 // add this call for any other surv rate groups
1370 #endif // PRODUCT
1371 }
1372
1373 #ifndef PRODUCT
1374 // for debugging, bit of a hack...
1375 static char*
1376 region_num_to_mbs(int length) {
1377 static char buffer[64];
1378 double bytes = (double) (length * HeapRegion::GrainBytes);
1379 double mbs = bytes / (double) (1024 * 1024);
1380 sprintf(buffer, "%7.2lfMB", mbs);
1381 return buffer;
1382 }
1383 #endif // PRODUCT
1384
1385 uint G1CollectorPolicy::max_regions(int purpose) {
1386 switch (purpose) {
1387 case GCAllocForSurvived:
1388 return _max_survivor_regions;
1389 case GCAllocForTenured:
1390 return REGIONS_UNLIMITED;
1391 default:
1392 ShouldNotReachHere();
1393 return REGIONS_UNLIMITED;
1394 };
1395 }
1396
1397 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1398 uint expansion_region_num = 0;
1399 if (GCLockerEdenExpansionPercent > 0) {
1400 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1401 double expansion_region_num_d = perc * (double) _young_list_target_length;
1402 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1403 // less than 1.0) we'll get 1.
1404 expansion_region_num = (uint) ceil(expansion_region_num_d);
1405 } else {
1406 assert(expansion_region_num == 0, "sanity");
1407 }
1408 _young_list_max_length = _young_list_target_length + expansion_region_num;
1409 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1410 }
1411
1412 // Calculates survivor space parameters.
1413 void G1CollectorPolicy::update_survivors_policy() {
1414 double max_survivor_regions_d =
1415 (double) _young_list_target_length / (double) SurvivorRatio;
1416 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1417 // smaller than 1.0) we'll get 1.
1418 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1419
1420 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1421 HeapRegion::GrainWords * _max_survivor_regions);
1422 }
1423
1424 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1425 GCCause::Cause gc_cause) {
1426 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1427 if (!during_cycle) {
1428 ergo_verbose1(ErgoConcCycles,
1429 "request concurrent cycle initiation",
1430 ergo_format_reason("requested by GC cause")
1431 ergo_format_str("GC cause"),
1432 GCCause::to_string(gc_cause));
1433 set_initiate_conc_mark_if_possible();
1434 return true;
1435 } else {
1436 ergo_verbose1(ErgoConcCycles,
1437 "do not request concurrent cycle initiation",
1438 ergo_format_reason("concurrent cycle already in progress")
1439 ergo_format_str("GC cause"),
1440 GCCause::to_string(gc_cause));
1441 return false;
1442 }
1443 }
1444
1445 void
1446 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1447 // We are about to decide on whether this pause will be an
1448 // initial-mark pause.
1449
1450 // First, during_initial_mark_pause() should not be already set. We
1451 // will set it here if we have to. However, it should be cleared by
1452 // the end of the pause (it's only set for the duration of an
1453 // initial-mark pause).
1454 assert(!during_initial_mark_pause(), "pre-condition");
1455
1456 if (initiate_conc_mark_if_possible()) {
1457 // We had noticed on a previous pause that the heap occupancy has
1458 // gone over the initiating threshold and we should start a
1459 // concurrent marking cycle. So we might initiate one.
1460
1461 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1462 if (!during_cycle) {
1463 // The concurrent marking thread is not "during a cycle", i.e.,
1464 // it has completed the last one. So we can go ahead and
1465 // initiate a new cycle.
1466
1467 set_during_initial_mark_pause();
1468 // We do not allow mixed GCs during marking.
1469 if (!gcs_are_young()) {
1470 set_gcs_are_young(true);
1471 ergo_verbose0(ErgoMixedGCs,
1472 "end mixed GCs",
1473 ergo_format_reason("concurrent cycle is about to start"));
1474 }
1475
1476 // And we can now clear initiate_conc_mark_if_possible() as
1477 // we've already acted on it.
1478 clear_initiate_conc_mark_if_possible();
1479
1480 ergo_verbose0(ErgoConcCycles,
1481 "initiate concurrent cycle",
1482 ergo_format_reason("concurrent cycle initiation requested"));
1483 } else {
1484 // The concurrent marking thread is still finishing up the
1485 // previous cycle. If we start one right now the two cycles
1486 // overlap. In particular, the concurrent marking thread might
1487 // be in the process of clearing the next marking bitmap (which
1488 // we will use for the next cycle if we start one). Starting a
1489 // cycle now will be bad given that parts of the marking
1490 // information might get cleared by the marking thread. And we
1491 // cannot wait for the marking thread to finish the cycle as it
1492 // periodically yields while clearing the next marking bitmap
1493 // and, if it's in a yield point, it's waiting for us to
1494 // finish. So, at this point we will not start a cycle and we'll
1495 // let the concurrent marking thread complete the last one.
1496 ergo_verbose0(ErgoConcCycles,
1497 "do not initiate concurrent cycle",
1498 ergo_format_reason("concurrent cycle already in progress"));
1499 }
1500 }
1501 }
1502
1503 class KnownGarbageClosure: public HeapRegionClosure {
1504 G1CollectedHeap* _g1h;
1505 CollectionSetChooser* _hrSorted;
1506
1507 public:
1508 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1509 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1510
1511 bool doHeapRegion(HeapRegion* r) {
1512 // We only include humongous regions in collection
1513 // sets when concurrent mark shows that their contained object is
1514 // unreachable.
1515
1516 // Do we have any marking information for this region?
1517 if (r->is_marked()) {
1518 // We will skip any region that's currently used as an old GC
1519 // alloc region (we should not consider those for collection
1520 // before we fill them up).
1521 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1522 _hrSorted->add_region(r);
1523 }
1524 }
1525 return false;
1526 }
1527 };
1528
1529 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1530 G1CollectedHeap* _g1h;
1531 CSetChooserParUpdater _cset_updater;
1532
1533 public:
1534 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1535 uint chunk_size) :
1536 _g1h(G1CollectedHeap::heap()),
1537 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1538
1539 bool doHeapRegion(HeapRegion* r) {
1540 // Do we have any marking information for this region?
1541 if (r->is_marked()) {
1542 // We will skip any region that's currently used as an old GC
1543 // alloc region (we should not consider those for collection
1544 // before we fill them up).
1545 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1546 _cset_updater.add_region(r);
1547 }
1548 }
1549 return false;
1550 }
1551 };
1552
1553 class ParKnownGarbageTask: public AbstractGangTask {
1554 CollectionSetChooser* _hrSorted;
1555 uint _chunk_size;
1556 G1CollectedHeap* _g1;
1557 public:
1558 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1559 AbstractGangTask("ParKnownGarbageTask"),
1560 _hrSorted(hrSorted), _chunk_size(chunk_size),
1561 _g1(G1CollectedHeap::heap()) { }
1562
1563 void work(uint worker_id) {
1564 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1565
1566 // Back to zero for the claim value.
1567 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1568 _g1->workers()->active_workers(),
1569 HeapRegion::InitialClaimValue);
1570 }
1571 };
1572
1573 void
1574 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1575 _collectionSetChooser->clear();
1576
1577 uint region_num = _g1->n_regions();
1578 if (G1CollectedHeap::use_parallel_gc_threads()) {
1579 const uint OverpartitionFactor = 4;
1580 uint WorkUnit;
1581 // The use of MinChunkSize = 8 in the original code
1582 // causes some assertion failures when the total number of
1583 // region is less than 8. The code here tries to fix that.
1584 // Should the original code also be fixed?
1585 if (no_of_gc_threads > 0) {
1586 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1587 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1588 MinWorkUnit);
1589 } else {
1590 assert(no_of_gc_threads > 0,
1591 "The active gc workers should be greater than 0");
1592 // In a product build do something reasonable to avoid a crash.
1593 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1594 WorkUnit =
1595 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1596 MinWorkUnit);
1597 }
1598 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1599 WorkUnit);
1600 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1601 (int) WorkUnit);
1602 _g1->workers()->run_task(&parKnownGarbageTask);
1603
1604 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1605 "sanity check");
1606 } else {
1607 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1608 _g1->heap_region_iterate(&knownGarbagecl);
1609 }
1610
1611 _collectionSetChooser->sort_regions();
1612
1613 double end_sec = os::elapsedTime();
1614 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1615 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1616 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1617 _prev_collection_pause_end_ms += elapsed_time_ms;
1618 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1619 }
1620
1621 // Add the heap region at the head of the non-incremental collection set
1622 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1623 assert(_inc_cset_build_state == Active, "Precondition");
1624 assert(!hr->is_young(), "non-incremental add of young region");
1625
1626 assert(!hr->in_collection_set(), "should not already be in the CSet");
1627 hr->set_in_collection_set(true);
1628 hr->set_next_in_collection_set(_collection_set);
1629 _collection_set = hr;
1630 _collection_set_bytes_used_before += hr->used();
1631 _g1->register_region_with_in_cset_fast_test(hr);
1632 size_t rs_length = hr->rem_set()->occupied();
1633 _recorded_rs_lengths += rs_length;
1634 _old_cset_region_length += 1;
1635 }
1636
1637 // Initialize the per-collection-set information
1638 void G1CollectorPolicy::start_incremental_cset_building() {
1639 assert(_inc_cset_build_state == Inactive, "Precondition");
1640
1641 _inc_cset_head = NULL;
1642 _inc_cset_tail = NULL;
1643 _inc_cset_bytes_used_before = 0;
1644
1645 _inc_cset_max_finger = 0;
1646 _inc_cset_recorded_rs_lengths = 0;
1647 _inc_cset_recorded_rs_lengths_diffs = 0;
1648 _inc_cset_predicted_elapsed_time_ms = 0.0;
1649 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1650 _inc_cset_build_state = Active;
1651 }
1652
1653 void G1CollectorPolicy::finalize_incremental_cset_building() {
1654 assert(_inc_cset_build_state == Active, "Precondition");
1655 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1656
1657 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1658 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1659 // that adds a new region to the CSet. Further updates by the
1660 // concurrent refinement thread that samples the young RSet lengths
1661 // are accumulated in the *_diffs fields. Here we add the diffs to
1662 // the "main" fields.
1663
1664 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1665 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1666 } else {
1667 // This is defensive. The diff should in theory be always positive
1668 // as RSets can only grow between GCs. However, given that we
1669 // sample their size concurrently with other threads updating them
1670 // it's possible that we might get the wrong size back, which
1671 // could make the calculations somewhat inaccurate.
1672 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1673 if (_inc_cset_recorded_rs_lengths >= diffs) {
1674 _inc_cset_recorded_rs_lengths -= diffs;
1675 } else {
1676 _inc_cset_recorded_rs_lengths = 0;
1677 }
1678 }
1679 _inc_cset_predicted_elapsed_time_ms +=
1680 _inc_cset_predicted_elapsed_time_ms_diffs;
1681
1682 _inc_cset_recorded_rs_lengths_diffs = 0;
1683 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1684 }
1685
1686 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1687 // This routine is used when:
1688 // * adding survivor regions to the incremental cset at the end of an
1689 // evacuation pause,
1690 // * adding the current allocation region to the incremental cset
1691 // when it is retired, and
1692 // * updating existing policy information for a region in the
1693 // incremental cset via young list RSet sampling.
1694 // Therefore this routine may be called at a safepoint by the
1695 // VM thread, or in-between safepoints by mutator threads (when
1696 // retiring the current allocation region) or a concurrent
1697 // refine thread (RSet sampling).
1698
1699 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1700 size_t used_bytes = hr->used();
1701 _inc_cset_recorded_rs_lengths += rs_length;
1702 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1703 _inc_cset_bytes_used_before += used_bytes;
1704
1705 // Cache the values we have added to the aggregated informtion
1706 // in the heap region in case we have to remove this region from
1707 // the incremental collection set, or it is updated by the
1708 // rset sampling code
1709 hr->set_recorded_rs_length(rs_length);
1710 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1711 }
1712
1713 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1714 size_t new_rs_length) {
1715 // Update the CSet information that is dependent on the new RS length
1716 assert(hr->is_young(), "Precondition");
1717 assert(!SafepointSynchronize::is_at_safepoint(),
1718 "should not be at a safepoint");
1719
1720 // We could have updated _inc_cset_recorded_rs_lengths and
1721 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1722 // that atomically, as this code is executed by a concurrent
1723 // refinement thread, potentially concurrently with a mutator thread
1724 // allocating a new region and also updating the same fields. To
1725 // avoid the atomic operations we accumulate these updates on two
1726 // separate fields (*_diffs) and we'll just add them to the "main"
1727 // fields at the start of a GC.
1728
1729 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1730 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1731 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1732
1733 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1734 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1735 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1736 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1737
1738 hr->set_recorded_rs_length(new_rs_length);
1739 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1740 }
1741
1742 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1743 assert(hr->is_young(), "invariant");
1744 assert(hr->young_index_in_cset() > -1, "should have already been set");
1745 assert(_inc_cset_build_state == Active, "Precondition");
1746
1747 // We need to clear and set the cached recorded/cached collection set
1748 // information in the heap region here (before the region gets added
1749 // to the collection set). An individual heap region's cached values
1750 // are calculated, aggregated with the policy collection set info,
1751 // and cached in the heap region here (initially) and (subsequently)
1752 // by the Young List sampling code.
1753
1754 size_t rs_length = hr->rem_set()->occupied();
1755 add_to_incremental_cset_info(hr, rs_length);
1756
1757 HeapWord* hr_end = hr->end();
1758 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1759
1760 assert(!hr->in_collection_set(), "invariant");
1761 hr->set_in_collection_set(true);
1762 assert( hr->next_in_collection_set() == NULL, "invariant");
1763
1764 _g1->register_region_with_in_cset_fast_test(hr);
1765 }
1766
1767 // Add the region at the RHS of the incremental cset
1768 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1769 // We should only ever be appending survivors at the end of a pause
1770 assert( hr->is_survivor(), "Logic");
1771
1772 // Do the 'common' stuff
1773 add_region_to_incremental_cset_common(hr);
1774
1775 // Now add the region at the right hand side
1776 if (_inc_cset_tail == NULL) {
1777 assert(_inc_cset_head == NULL, "invariant");
1778 _inc_cset_head = hr;
1779 } else {
1780 _inc_cset_tail->set_next_in_collection_set(hr);
1781 }
1782 _inc_cset_tail = hr;
1783 }
1784
1785 // Add the region to the LHS of the incremental cset
1786 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1787 // Survivors should be added to the RHS at the end of a pause
1788 assert(!hr->is_survivor(), "Logic");
1789
1790 // Do the 'common' stuff
1791 add_region_to_incremental_cset_common(hr);
1792
1793 // Add the region at the left hand side
1794 hr->set_next_in_collection_set(_inc_cset_head);
1795 if (_inc_cset_head == NULL) {
1796 assert(_inc_cset_tail == NULL, "Invariant");
1797 _inc_cset_tail = hr;
1798 }
1799 _inc_cset_head = hr;
1800 }
1801
1802 #ifndef PRODUCT
1803 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1804 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1805
1806 st->print_cr("\nCollection_set:");
1807 HeapRegion* csr = list_head;
1808 while (csr != NULL) {
1809 HeapRegion* next = csr->next_in_collection_set();
1810 assert(csr->in_collection_set(), "bad CS");
1811 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1812 HR_FORMAT_PARAMS(csr),
1813 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1814 csr->age_in_surv_rate_group_cond());
1815 csr = next;
1816 }
1817 }
1818 #endif // !PRODUCT
1819
1820 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1821 // Returns the given amount of reclaimable bytes (that represents
1822 // the amount of reclaimable space still to be collected) as a
1823 // percentage of the current heap capacity.
1824 size_t capacity_bytes = _g1->capacity();
1825 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1826 }
1827
1828 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1829 const char* false_action_str) {
1830 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1831 if (cset_chooser->is_empty()) {
1832 ergo_verbose0(ErgoMixedGCs,
1833 false_action_str,
1834 ergo_format_reason("candidate old regions not available"));
1835 return false;
1836 }
1837
1838 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1839 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1840 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1841 double threshold = (double) G1HeapWastePercent;
1842 if (reclaimable_perc <= threshold) {
1843 ergo_verbose4(ErgoMixedGCs,
1844 false_action_str,
1845 ergo_format_reason("reclaimable percentage not over threshold")
1846 ergo_format_region("candidate old regions")
1847 ergo_format_byte_perc("reclaimable")
1848 ergo_format_perc("threshold"),
1849 cset_chooser->remaining_regions(),
1850 reclaimable_bytes,
1851 reclaimable_perc, threshold);
1852 return false;
1853 }
1854
1855 ergo_verbose4(ErgoMixedGCs,
1856 true_action_str,
1857 ergo_format_reason("candidate old regions available")
1858 ergo_format_region("candidate old regions")
1859 ergo_format_byte_perc("reclaimable")
1860 ergo_format_perc("threshold"),
1861 cset_chooser->remaining_regions(),
1862 reclaimable_bytes,
1863 reclaimable_perc, threshold);
1864 return true;
1865 }
1866
1867 uint G1CollectorPolicy::calc_min_old_cset_length() {
1868 // The min old CSet region bound is based on the maximum desired
1869 // number of mixed GCs after a cycle. I.e., even if some old regions
1870 // look expensive, we should add them to the CSet anyway to make
1871 // sure we go through the available old regions in no more than the
1872 // maximum desired number of mixed GCs.
1873 //
1874 // The calculation is based on the number of marked regions we added
1875 // to the CSet chooser in the first place, not how many remain, so
1876 // that the result is the same during all mixed GCs that follow a cycle.
1877
1878 const size_t region_num = (size_t) _collectionSetChooser->length();
1879 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1880 size_t result = region_num / gc_num;
1881 // emulate ceiling
1882 if (result * gc_num < region_num) {
1883 result += 1;
1884 }
1885 return (uint) result;
1886 }
1887
1888 uint G1CollectorPolicy::calc_max_old_cset_length() {
1889 // The max old CSet region bound is based on the threshold expressed
1890 // as a percentage of the heap size. I.e., it should bound the
1891 // number of old regions added to the CSet irrespective of how many
1892 // of them are available.
1893
1894 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1895 const size_t region_num = g1h->n_regions();
1896 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1897 size_t result = region_num * perc / 100;
1898 // emulate ceiling
1899 if (100 * result < region_num * perc) {
1900 result += 1;
1901 }
1902 return (uint) result;
1903 }
1904
1905 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1906 double young_start_time_sec = os::elapsedTime();
1907
1908 YoungList* young_list = _g1->young_list();
1909 finalize_incremental_cset_building();
1910
1911 guarantee(target_pause_time_ms > 0.0,
1912 err_msg("target_pause_time_ms = %1.6lf should be positive",
1913 target_pause_time_ms));
1914 guarantee(_collection_set == NULL, "Precondition");
1915
1916 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1917 double predicted_pause_time_ms = base_time_ms;
1918 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1919
1920 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1921 "start choosing CSet",
1922 ergo_format_size("_pending_cards")
1923 ergo_format_ms("predicted base time")
1924 ergo_format_ms("remaining time")
1925 ergo_format_ms("target pause time"),
1926 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1927
1928 _last_gc_was_young = gcs_are_young() ? true : false;
1929
1930 if (_last_gc_was_young) {
1931 _trace_gen0_time_data.increment_young_collection_count();
1932 } else {
1933 _trace_gen0_time_data.increment_mixed_collection_count();
1934 }
1935
1936 // The young list is laid with the survivor regions from the previous
1937 // pause are appended to the RHS of the young list, i.e.
1938 // [Newly Young Regions ++ Survivors from last pause].
1939
1940 uint survivor_region_length = young_list->survivor_length();
1941 uint eden_region_length = young_list->length() - survivor_region_length;
1942 init_cset_region_lengths(eden_region_length, survivor_region_length);
1943
1944 HeapRegion* hr = young_list->first_survivor_region();
1945 while (hr != NULL) {
1946 assert(hr->is_survivor(), "badly formed young list");
1947 hr->set_young();
1948 hr = hr->get_next_young_region();
1949 }
1950
1951 // Clear the fields that point to the survivor list - they are all young now.
1952 young_list->clear_survivors();
1953
1954 _collection_set = _inc_cset_head;
1955 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1956 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1957 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1958
1959 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1960 "add young regions to CSet",
1961 ergo_format_region("eden")
1962 ergo_format_region("survivors")
1963 ergo_format_ms("predicted young region time"),
1964 eden_region_length, survivor_region_length,
1965 _inc_cset_predicted_elapsed_time_ms);
1966
1967 // The number of recorded young regions is the incremental
1968 // collection set's current size
1969 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1970
1971 double young_end_time_sec = os::elapsedTime();
1972 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1973
1974 // Set the start of the non-young choice time.
1975 double non_young_start_time_sec = young_end_time_sec;
1976
1977 if (!gcs_are_young()) {
1978 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1979 cset_chooser->verify();
1980 const uint min_old_cset_length = calc_min_old_cset_length();
1981 const uint max_old_cset_length = calc_max_old_cset_length();
1982
1983 uint expensive_region_num = 0;
1984 bool check_time_remaining = adaptive_young_list_length();
1985
1986 HeapRegion* hr = cset_chooser->peek();
1987 while (hr != NULL) {
1988 if (old_cset_region_length() >= max_old_cset_length) {
1989 // Added maximum number of old regions to the CSet.
1990 ergo_verbose2(ErgoCSetConstruction,
1991 "finish adding old regions to CSet",
1992 ergo_format_reason("old CSet region num reached max")
1993 ergo_format_region("old")
1994 ergo_format_region("max"),
1995 old_cset_region_length(), max_old_cset_length);
1996 break;
1997 }
1998
1999
2000 // Stop adding regions if the remaining reclaimable space is
2001 // not above G1HeapWastePercent.
2002 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2003 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2004 double threshold = (double) G1HeapWastePercent;
2005 if (reclaimable_perc <= threshold) {
2006 // We've added enough old regions that the amount of uncollected
2007 // reclaimable space is at or below the waste threshold. Stop
2008 // adding old regions to the CSet.
2009 ergo_verbose5(ErgoCSetConstruction,
2010 "finish adding old regions to CSet",
2011 ergo_format_reason("reclaimable percentage not over threshold")
2012 ergo_format_region("old")
2013 ergo_format_region("max")
2014 ergo_format_byte_perc("reclaimable")
2015 ergo_format_perc("threshold"),
2016 old_cset_region_length(),
2017 max_old_cset_length,
2018 reclaimable_bytes,
2019 reclaimable_perc, threshold);
2020 break;
2021 }
2022
2023 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2024 if (check_time_remaining) {
2025 if (predicted_time_ms > time_remaining_ms) {
2026 // Too expensive for the current CSet.
2027
2028 if (old_cset_region_length() >= min_old_cset_length) {
2029 // We have added the minimum number of old regions to the CSet,
2030 // we are done with this CSet.
2031 ergo_verbose4(ErgoCSetConstruction,
2032 "finish adding old regions to CSet",
2033 ergo_format_reason("predicted time is too high")
2034 ergo_format_ms("predicted time")
2035 ergo_format_ms("remaining time")
2036 ergo_format_region("old")
2037 ergo_format_region("min"),
2038 predicted_time_ms, time_remaining_ms,
2039 old_cset_region_length(), min_old_cset_length);
2040 break;
2041 }
2042
2043 // We'll add it anyway given that we haven't reached the
2044 // minimum number of old regions.
2045 expensive_region_num += 1;
2046 }
2047 } else {
2048 if (old_cset_region_length() >= min_old_cset_length) {
2049 // In the non-auto-tuning case, we'll finish adding regions
2050 // to the CSet if we reach the minimum.
2051 ergo_verbose2(ErgoCSetConstruction,
2052 "finish adding old regions to CSet",
2053 ergo_format_reason("old CSet region num reached min")
2054 ergo_format_region("old")
2055 ergo_format_region("min"),
2056 old_cset_region_length(), min_old_cset_length);
2057 break;
2058 }
2059 }
2060
2061 // We will add this region to the CSet.
2062 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2063 predicted_pause_time_ms += predicted_time_ms;
2064 cset_chooser->remove_and_move_to_next(hr);
2065 _g1->old_set_remove(hr);
2066 add_old_region_to_cset(hr);
2067
2068 hr = cset_chooser->peek();
2069 }
2070 if (hr == NULL) {
2071 ergo_verbose0(ErgoCSetConstruction,
2072 "finish adding old regions to CSet",
2073 ergo_format_reason("candidate old regions not available"));
2074 }
2075
2076 if (expensive_region_num > 0) {
2077 // We print the information once here at the end, predicated on
2078 // whether we added any apparently expensive regions or not, to
2079 // avoid generating output per region.
2080 ergo_verbose4(ErgoCSetConstruction,
2081 "added expensive regions to CSet",
2082 ergo_format_reason("old CSet region num not reached min")
2083 ergo_format_region("old")
2084 ergo_format_region("expensive")
2085 ergo_format_region("min")
2086 ergo_format_ms("remaining time"),
2087 old_cset_region_length(),
2088 expensive_region_num,
2089 min_old_cset_length,
2090 time_remaining_ms);
2091 }
2092
2093 cset_chooser->verify();
2094 }
2095
2096 stop_incremental_cset_building();
2097
2098 ergo_verbose5(ErgoCSetConstruction,
2099 "finish choosing CSet",
2100 ergo_format_region("eden")
2101 ergo_format_region("survivors")
2102 ergo_format_region("old")
2103 ergo_format_ms("predicted pause time")
2104 ergo_format_ms("target pause time"),
2105 eden_region_length, survivor_region_length,
2106 old_cset_region_length(),
2107 predicted_pause_time_ms, target_pause_time_ms);
2108
2109 double non_young_end_time_sec = os::elapsedTime();
2110 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2111 evacuation_info.set_collectionset_regions(cset_region_length());
2112 }
2113
2114 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2115 if(TraceGen0Time) {
2116 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2117 }
2118 }
2119
2120 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2121 if(TraceGen0Time) {
2122 _all_yield_times_ms.add(yield_time_ms);
2123 }
2124 }
2125
2126 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2127 if(TraceGen0Time) {
2128 _total.add(pause_time_ms);
2129 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2130 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2131 _parallel.add(phase_times->cur_collection_par_time_ms());
2132 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2133 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2134 _update_rs.add(phase_times->average_last_update_rs_time());
2135 _scan_rs.add(phase_times->average_last_scan_rs_time());
2136 _obj_copy.add(phase_times->average_last_obj_copy_time());
2137 _termination.add(phase_times->average_last_termination_time());
2138
2139 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2140 phase_times->average_last_satb_filtering_times_ms() +
2141 phase_times->average_last_update_rs_time() +
2142 phase_times->average_last_scan_rs_time() +
2143 phase_times->average_last_obj_copy_time() +
2144 + phase_times->average_last_termination_time();
2145
2146 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2147 _parallel_other.add(parallel_other_time);
2148 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2149 }
2150 }
2151
2152 void TraceGen0TimeData::increment_young_collection_count() {
2153 if(TraceGen0Time) {
2154 ++_young_pause_num;
2155 }
2156 }
2157
2158 void TraceGen0TimeData::increment_mixed_collection_count() {
2159 if(TraceGen0Time) {
2160 ++_mixed_pause_num;
2161 }
2162 }
2163
2164 void TraceGen0TimeData::print_summary(const char* str,
2165 const NumberSeq* seq) const {
2166 double sum = seq->sum();
2167 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2168 str, sum / 1000.0, seq->avg());
2169 }
2170
2171 void TraceGen0TimeData::print_summary_sd(const char* str,
2172 const NumberSeq* seq) const {
2173 print_summary(str, seq);
2174 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2175 "(num", seq->num(), seq->sd(), seq->maximum());
2176 }
2177
2178 void TraceGen0TimeData::print() const {
2179 if (!TraceGen0Time) {
2180 return;
2181 }
2182
2183 gclog_or_tty->print_cr("ALL PAUSES");
2184 print_summary_sd(" Total", &_total);
2185 gclog_or_tty->print_cr("");
2186 gclog_or_tty->print_cr("");
2187 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2188 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2189 gclog_or_tty->print_cr("");
2190
2191 gclog_or_tty->print_cr("EVACUATION PAUSES");
2192
2193 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2194 gclog_or_tty->print_cr("none");
2195 } else {
2196 print_summary_sd(" Evacuation Pauses", &_total);
2197 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2198 print_summary(" Parallel Time", &_parallel);
2199 print_summary(" Ext Root Scanning", &_ext_root_scan);
2200 print_summary(" SATB Filtering", &_satb_filtering);
2201 print_summary(" Update RS", &_update_rs);
2202 print_summary(" Scan RS", &_scan_rs);
2203 print_summary(" Object Copy", &_obj_copy);
2204 print_summary(" Termination", &_termination);
2205 print_summary(" Parallel Other", &_parallel_other);
2206 print_summary(" Clear CT", &_clear_ct);
2207 print_summary(" Other", &_other);
2208 }
2209 gclog_or_tty->print_cr("");
2210
2211 gclog_or_tty->print_cr("MISC");
2212 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2213 print_summary_sd(" Yields", &_all_yield_times_ms);
2214 }
2215
2216 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2217 if (TraceGen1Time) {
2218 _all_full_gc_times.add(full_gc_time_ms);
2219 }
2220 }
2221
2222 void TraceGen1TimeData::print() const {
2223 if (!TraceGen1Time) {
2224 return;
2225 }
2226
2227 if (_all_full_gc_times.num() > 0) {
2228 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2229 _all_full_gc_times.num(),
2230 _all_full_gc_times.sum() / 1000.0);
2231 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2232 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2233 _all_full_gc_times.sd(),
2234 _all_full_gc_times.maximum());
2235 }
2236 }