1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef __clang_major__
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "gc_implementation/g1/concurrentG1Refine.hpp"
32 #include "gc_implementation/g1/concurrentMark.hpp"
33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
34 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
35 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
36 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/heapRegionRemSet.hpp"
40 #include "gc_implementation/shared/gcPolicyCounters.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/java.hpp"
43 #include "runtime/mutexLocker.hpp"
44 #include "utilities/debug.hpp"
45
46 // Different defaults for different number of GC threads
47 // They were chosen by running GCOld and SPECjbb on debris with different
48 // numbers of GC threads and choosing them based on the results
49
50 // all the same
51 static double rs_length_diff_defaults[] = {
52 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
53 };
54
55 static double cost_per_card_ms_defaults[] = {
56 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
57 };
58
59 // all the same
60 static double young_cards_per_entry_ratio_defaults[] = {
61 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
62 };
63
64 static double cost_per_entry_ms_defaults[] = {
65 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
66 };
67
68 static double cost_per_byte_ms_defaults[] = {
69 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
70 };
71
72 // these should be pretty consistent
73 static double constant_other_time_ms_defaults[] = {
74 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
75 };
76
77
78 static double young_other_cost_per_region_ms_defaults[] = {
79 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
80 };
81
82 static double non_young_other_cost_per_region_ms_defaults[] = {
83 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
84 };
85
86 G1CollectorPolicy::G1CollectorPolicy() :
87 _parallel_gc_threads(ParallelGCThreads),
88
89 _phase_times(NULL),
90
91 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
92 _stop_world_start(0.0),
93
94 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
95 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
96
97 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _prev_collection_pause_end_ms(0.0),
99 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
104 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
105 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
106 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
108 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
109 _non_young_other_cost_per_region_ms_seq(
110 new TruncatedSeq(TruncatedSeqLength)),
111
112 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
113 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
114
115 _pause_time_target_ms((double) MaxGCPauseMillis),
116
117 _gcs_are_young(true),
118
119 _during_marking(false),
120 _in_marking_window(false),
121 _in_marking_window_im(false),
122
123 _recent_prev_end_times_for_all_gcs_sec(
124 new TruncatedSeq(NumPrevPausesForHeuristics)),
125
126 _recent_avg_pause_time_ratio(0.0),
127
128 _initiate_conc_mark_if_possible(false),
129 _during_initial_mark_pause(false),
130 _last_young_gc(false),
131 _last_gc_was_young(false),
132
133 _eden_used_bytes_before_gc(0),
134 _survivor_used_bytes_before_gc(0),
135 _heap_used_bytes_before_gc(0),
136 _metaspace_used_bytes_before_gc(0),
137 _eden_capacity_bytes_before_gc(0),
138 _heap_capacity_bytes_before_gc(0),
139
140 _eden_cset_region_length(0),
141 _survivor_cset_region_length(0),
142 _old_cset_region_length(0),
143
144 _sigma(G1ConfidencePercent / 100.0),
145
146 _collection_set(NULL),
147 _collection_set_bytes_used_before(0),
148
149 // Incremental CSet attributes
150 _inc_cset_build_state(Inactive),
151 _inc_cset_head(NULL),
152 _inc_cset_tail(NULL),
153 _inc_cset_bytes_used_before(0),
154 _inc_cset_max_finger(NULL),
155 _inc_cset_recorded_rs_lengths(0),
156 _inc_cset_recorded_rs_lengths_diffs(0),
157 _inc_cset_predicted_elapsed_time_ms(0.0),
158 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
159
160 // add here any more surv rate groups
161 _recorded_survivor_regions(0),
162 _recorded_survivor_head(NULL),
163 _recorded_survivor_tail(NULL),
164 _survivors_age_table(true),
165
166 _gc_overhead_perc(0.0) {
167
168 // SurvRateGroups below must be initialized after '_sigma' because they
169 // indirectly access '_sigma' through this object passed to their constructor.
170 _short_lived_surv_rate_group =
171 new SurvRateGroup(this, "Short Lived", G1YoungSurvRateNumRegionsSummary);
172 _survivor_surv_rate_group =
173 new SurvRateGroup(this, "Survivor", G1YoungSurvRateNumRegionsSummary);
174
175 // Set up the region size and associated fields. Given that the
176 // policy is created before the heap, we have to set this up here,
177 // so it's done as soon as possible.
178
179 // It would have been natural to pass initial_heap_byte_size() and
180 // max_heap_byte_size() to setup_heap_region_size() but those have
181 // not been set up at this point since they should be aligned with
182 // the region size. So, there is a circular dependency here. We base
183 // the region size on the heap size, but the heap size should be
184 // aligned with the region size. To get around this we use the
185 // unaligned values for the heap.
186 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
187 HeapRegionRemSet::setup_remset_size();
188
189 G1ErgoVerbose::initialize();
190 if (PrintAdaptiveSizePolicy) {
191 // Currently, we only use a single switch for all the heuristics.
192 G1ErgoVerbose::set_enabled(true);
193 // Given that we don't currently have a verboseness level
194 // parameter, we'll hardcode this to high. This can be easily
195 // changed in the future.
196 G1ErgoVerbose::set_level(ErgoHigh);
197 } else {
198 G1ErgoVerbose::set_enabled(false);
199 }
200
201 // Verify PLAB sizes
202 const size_t region_size = HeapRegion::GrainWords;
203 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
204 char buffer[128];
205 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
206 OldPLABSize > region_size ? "Old" : "Young", region_size);
207 vm_exit_during_initialization(buffer);
208 }
209
210 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
211 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
212
213 int index = MIN2(_parallel_gc_threads - 1, 7);
214
215 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
216 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
217 _young_cards_per_entry_ratio_seq->add(
218 young_cards_per_entry_ratio_defaults[index]);
219 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
220 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
221 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
222 _young_other_cost_per_region_ms_seq->add(
223 young_other_cost_per_region_ms_defaults[index]);
224 _non_young_other_cost_per_region_ms_seq->add(
225 non_young_other_cost_per_region_ms_defaults[index]);
226
227 // Below, we might need to calculate the pause time target based on
228 // the pause interval. When we do so we are going to give G1 maximum
229 // flexibility and allow it to do pauses when it needs to. So, we'll
230 // arrange that the pause interval to be pause time target + 1 to
231 // ensure that a) the pause time target is maximized with respect to
232 // the pause interval and b) we maintain the invariant that pause
233 // time target < pause interval. If the user does not want this
234 // maximum flexibility, they will have to set the pause interval
235 // explicitly.
236
237 // First make sure that, if either parameter is set, its value is
238 // reasonable.
239 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
240 if (MaxGCPauseMillis < 1) {
241 vm_exit_during_initialization("MaxGCPauseMillis should be "
242 "greater than 0");
243 }
244 }
245 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
246 if (GCPauseIntervalMillis < 1) {
247 vm_exit_during_initialization("GCPauseIntervalMillis should be "
248 "greater than 0");
249 }
250 }
251
252 // Then, if the pause time target parameter was not set, set it to
253 // the default value.
254 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
255 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
256 // The default pause time target in G1 is 200ms
257 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
258 } else {
259 // We do not allow the pause interval to be set without the
260 // pause time target
261 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
262 "without setting MaxGCPauseMillis");
263 }
264 }
265
266 // Then, if the interval parameter was not set, set it according to
267 // the pause time target (this will also deal with the case when the
268 // pause time target is the default value).
269 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
270 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
271 }
272
273 // Finally, make sure that the two parameters are consistent.
274 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
275 char buffer[256];
276 jio_snprintf(buffer, 256,
277 "MaxGCPauseMillis (%u) should be less than "
278 "GCPauseIntervalMillis (%u)",
279 MaxGCPauseMillis, GCPauseIntervalMillis);
280 vm_exit_during_initialization(buffer);
281 }
282
283 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
284 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
285 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
286
287 // start conservatively (around 50ms is about right)
288 _concurrent_mark_remark_times_ms->add(0.05);
289 _concurrent_mark_cleanup_times_ms->add(0.20);
290 _tenuring_threshold = MaxTenuringThreshold;
291 // _max_survivor_regions will be calculated by
292 // update_young_list_target_length() during initialization.
293 _max_survivor_regions = 0;
294
295 assert(GCTimeRatio > 0,
296 "we should have set it to a default value set_g1_gc_flags() "
297 "if a user set it to 0");
298 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
299
300 uintx reserve_perc = G1ReservePercent;
301 // Put an artificial ceiling on this so that it's not set to a silly value.
302 if (reserve_perc > 50) {
303 reserve_perc = 50;
304 warning("G1ReservePercent is set to a value that is too large, "
305 "it's been updated to %u", reserve_perc);
306 }
307 _reserve_factor = (double) reserve_perc / 100.0;
308 // This will be set when the heap is expanded
309 // for the first time during initialization.
310 _reserve_regions = 0;
311
312 _collectionSetChooser = new CollectionSetChooser();
313 }
314
315 void G1CollectorPolicy::initialize_alignments() {
316 _space_alignment = HeapRegion::GrainBytes;
317 size_t card_table_alignment = GenRemSet::max_alignment_constraint();
318 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
319 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
320 }
321
322 void G1CollectorPolicy::initialize_flags() {
323 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
324 FLAG_SET_ERGO(uintx, G1HeapRegionSize, HeapRegion::GrainBytes);
325 }
326
327 if (SurvivorRatio < 1) {
328 vm_exit_during_initialization("Invalid survivor ratio specified");
329 }
330 CollectorPolicy::initialize_flags();
331 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
332 }
333
334 void G1CollectorPolicy::post_heap_initialize() {
335 uintx max_regions = G1CollectedHeap::heap()->max_regions();
336 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
337 if (max_young_size != MaxNewSize) {
338 FLAG_SET_ERGO(uintx, MaxNewSize, max_young_size);
339 }
340 }
341
342 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
343 _min_desired_young_length(0), _max_desired_young_length(0) {
344 if (FLAG_IS_CMDLINE(NewRatio)) {
345 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
346 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
347 } else {
348 _sizer_kind = SizerNewRatio;
349 _adaptive_size = false;
350 return;
351 }
352 }
353
354 if (NewSize > MaxNewSize) {
355 if (FLAG_IS_CMDLINE(MaxNewSize)) {
356 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
357 "A new max generation size of " SIZE_FORMAT "k will be used.",
358 NewSize/K, MaxNewSize/K, NewSize/K);
359 }
360 MaxNewSize = NewSize;
361 }
362
363 if (FLAG_IS_CMDLINE(NewSize)) {
364 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
365 1U);
366 if (FLAG_IS_CMDLINE(MaxNewSize)) {
367 _max_desired_young_length =
368 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
369 1U);
370 _sizer_kind = SizerMaxAndNewSize;
371 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
372 } else {
373 _sizer_kind = SizerNewSizeOnly;
374 }
375 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
376 _max_desired_young_length =
377 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
378 1U);
379 _sizer_kind = SizerMaxNewSizeOnly;
380 }
381 }
382
383 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
384 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
385 return MAX2(1U, default_value);
386 }
387
388 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
389 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
390 return MAX2(1U, default_value);
391 }
392
393 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
394 assert(number_of_heap_regions > 0, "Heap must be initialized");
395
396 switch (_sizer_kind) {
397 case SizerDefaults:
398 *min_young_length = calculate_default_min_length(number_of_heap_regions);
399 *max_young_length = calculate_default_max_length(number_of_heap_regions);
400 break;
401 case SizerNewSizeOnly:
402 *max_young_length = calculate_default_max_length(number_of_heap_regions);
403 *max_young_length = MAX2(*min_young_length, *max_young_length);
404 break;
405 case SizerMaxNewSizeOnly:
406 *min_young_length = calculate_default_min_length(number_of_heap_regions);
407 *min_young_length = MIN2(*min_young_length, *max_young_length);
408 break;
409 case SizerMaxAndNewSize:
410 // Do nothing. Values set on the command line, don't update them at runtime.
411 break;
412 case SizerNewRatio:
413 *min_young_length = number_of_heap_regions / (NewRatio + 1);
414 *max_young_length = *min_young_length;
415 break;
416 default:
417 ShouldNotReachHere();
418 }
419
420 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
421 }
422
423 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
424 // We need to pass the desired values because recalculation may not update these
425 // values in some cases.
426 uint temp = _min_desired_young_length;
427 uint result = _max_desired_young_length;
428 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
429 return result;
430 }
431
432 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
433 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
434 &_max_desired_young_length);
435 }
436
437 void G1CollectorPolicy::init() {
438 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads, G1Log::finest() ? G1CollectedHeap::num_ext_root_tasks() : 0);
439 // Set aside an initial future to_space.
440 _g1 = G1CollectedHeap::heap();
441
442 assert(Heap_lock->owned_by_self(), "Locking discipline.");
443
444 initialize_gc_policy_counters();
445
446 if (adaptive_young_list_length()) {
447 _young_list_fixed_length = 0;
448 } else {
449 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
450 }
451 _free_regions_at_end_of_collection = _g1->num_free_regions();
452 update_young_list_target_length();
453
454 // We may immediately start allocating regions and placing them on the
455 // collection set list. Initialize the per-collection set info
456 start_incremental_cset_building();
457 }
458
459 // Create the jstat counters for the policy.
460 void G1CollectorPolicy::initialize_gc_policy_counters() {
461 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
462 }
463
464 bool G1CollectorPolicy::predict_will_fit(uint young_length,
465 double base_time_ms,
466 uint base_free_regions,
467 double target_pause_time_ms) {
468 if (young_length >= base_free_regions) {
469 // end condition 1: not enough space for the young regions
470 return false;
471 }
472
473 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
474 size_t bytes_to_copy =
475 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
476 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
477 double young_other_time_ms = predict_young_other_time_ms(young_length);
478 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
479 if (pause_time_ms > target_pause_time_ms) {
480 // end condition 2: prediction is over the target pause time
481 return false;
482 }
483
484 size_t free_bytes =
485 (base_free_regions - young_length) * HeapRegion::GrainBytes;
486 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
487 // end condition 3: out-of-space (conservatively!)
488 return false;
489 }
490
491 // success!
492 return true;
493 }
494
495 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
496 // re-calculate the necessary reserve
497 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
498 // We use ceiling so that if reserve_regions_d is > 0.0 (but
499 // smaller than 1.0) we'll get 1.
500 _reserve_regions = (uint) ceil(reserve_regions_d);
501
502 _young_gen_sizer->heap_size_changed(new_number_of_regions);
503 }
504
505 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
506 uint base_min_length) {
507 uint desired_min_length = 0;
508 if (adaptive_young_list_length()) {
509 if (_alloc_rate_ms_seq->num() > 3) {
510 double now_sec = os::elapsedTime();
511 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
512 double alloc_rate_ms = predict_alloc_rate_ms();
513 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
514 } else {
515 // otherwise we don't have enough info to make the prediction
516 }
517 }
518 desired_min_length += base_min_length;
519 // make sure we don't go below any user-defined minimum bound
520 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
521 }
522
523 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
524 // Here, we might want to also take into account any additional
525 // constraints (i.e., user-defined minimum bound). Currently, we
526 // effectively don't set this bound.
527 return _young_gen_sizer->max_desired_young_length();
528 }
529
530 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
531 if (rs_lengths == (size_t) -1) {
532 // if it's set to the default value (-1), we should predict it;
533 // otherwise, use the given value.
534 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
535 }
536
537 // Calculate the absolute and desired min bounds.
538
539 // This is how many young regions we already have (currently: the survivors).
540 uint base_min_length = recorded_survivor_regions();
541 // This is the absolute minimum young length, which ensures that we
542 // can allocate one eden region in the worst-case.
543 uint absolute_min_length = base_min_length + 1;
544 uint desired_min_length =
545 calculate_young_list_desired_min_length(base_min_length);
546 if (desired_min_length < absolute_min_length) {
547 desired_min_length = absolute_min_length;
548 }
549
550 // Calculate the absolute and desired max bounds.
551
552 // We will try our best not to "eat" into the reserve.
553 uint absolute_max_length = 0;
554 if (_free_regions_at_end_of_collection > _reserve_regions) {
555 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
556 }
557 uint desired_max_length = calculate_young_list_desired_max_length();
558 if (desired_max_length > absolute_max_length) {
559 desired_max_length = absolute_max_length;
560 }
561
562 uint young_list_target_length = 0;
563 if (adaptive_young_list_length()) {
564 if (gcs_are_young()) {
565 young_list_target_length =
566 calculate_young_list_target_length(rs_lengths,
567 base_min_length,
568 desired_min_length,
569 desired_max_length);
570 _rs_lengths_prediction = rs_lengths;
571 } else {
572 // Don't calculate anything and let the code below bound it to
573 // the desired_min_length, i.e., do the next GC as soon as
574 // possible to maximize how many old regions we can add to it.
575 }
576 } else {
577 // The user asked for a fixed young gen so we'll fix the young gen
578 // whether the next GC is young or mixed.
579 young_list_target_length = _young_list_fixed_length;
580 }
581
582 // Make sure we don't go over the desired max length, nor under the
583 // desired min length. In case they clash, desired_min_length wins
584 // which is why that test is second.
585 if (young_list_target_length > desired_max_length) {
586 young_list_target_length = desired_max_length;
587 }
588 if (young_list_target_length < desired_min_length) {
589 young_list_target_length = desired_min_length;
590 }
591
592 assert(young_list_target_length > recorded_survivor_regions(),
593 "we should be able to allocate at least one eden region");
594 assert(young_list_target_length >= absolute_min_length, "post-condition");
595 _young_list_target_length = young_list_target_length;
596
597 update_max_gc_locker_expansion();
598 }
599
600 uint
601 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
602 uint base_min_length,
603 uint desired_min_length,
604 uint desired_max_length) {
605 assert(adaptive_young_list_length(), "pre-condition");
606 assert(gcs_are_young(), "only call this for young GCs");
607
608 // In case some edge-condition makes the desired max length too small...
609 if (desired_max_length <= desired_min_length) {
610 return desired_min_length;
611 }
612
613 // We'll adjust min_young_length and max_young_length not to include
614 // the already allocated young regions (i.e., so they reflect the
615 // min and max eden regions we'll allocate). The base_min_length
616 // will be reflected in the predictions by the
617 // survivor_regions_evac_time prediction.
618 assert(desired_min_length > base_min_length, "invariant");
619 uint min_young_length = desired_min_length - base_min_length;
620 assert(desired_max_length > base_min_length, "invariant");
621 uint max_young_length = desired_max_length - base_min_length;
622
623 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
624 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
625 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
626 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
627 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
628 double base_time_ms =
629 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
630 survivor_regions_evac_time;
631 uint available_free_regions = _free_regions_at_end_of_collection;
632 uint base_free_regions = 0;
633 if (available_free_regions > _reserve_regions) {
634 base_free_regions = available_free_regions - _reserve_regions;
635 }
636
637 // Here, we will make sure that the shortest young length that
638 // makes sense fits within the target pause time.
639
640 if (predict_will_fit(min_young_length, base_time_ms,
641 base_free_regions, target_pause_time_ms)) {
642 // The shortest young length will fit into the target pause time;
643 // we'll now check whether the absolute maximum number of young
644 // regions will fit in the target pause time. If not, we'll do
645 // a binary search between min_young_length and max_young_length.
646 if (predict_will_fit(max_young_length, base_time_ms,
647 base_free_regions, target_pause_time_ms)) {
648 // The maximum young length will fit into the target pause time.
649 // We are done so set min young length to the maximum length (as
650 // the result is assumed to be returned in min_young_length).
651 min_young_length = max_young_length;
652 } else {
653 // The maximum possible number of young regions will not fit within
654 // the target pause time so we'll search for the optimal
655 // length. The loop invariants are:
656 //
657 // min_young_length < max_young_length
658 // min_young_length is known to fit into the target pause time
659 // max_young_length is known not to fit into the target pause time
660 //
661 // Going into the loop we know the above hold as we've just
662 // checked them. Every time around the loop we check whether
663 // the middle value between min_young_length and
664 // max_young_length fits into the target pause time. If it
665 // does, it becomes the new min. If it doesn't, it becomes
666 // the new max. This way we maintain the loop invariants.
667
668 assert(min_young_length < max_young_length, "invariant");
669 uint diff = (max_young_length - min_young_length) / 2;
670 while (diff > 0) {
671 uint young_length = min_young_length + diff;
672 if (predict_will_fit(young_length, base_time_ms,
673 base_free_regions, target_pause_time_ms)) {
674 min_young_length = young_length;
675 } else {
676 max_young_length = young_length;
677 }
678 assert(min_young_length < max_young_length, "invariant");
679 diff = (max_young_length - min_young_length) / 2;
680 }
681 // The results is min_young_length which, according to the
682 // loop invariants, should fit within the target pause time.
683
684 // These are the post-conditions of the binary search above:
685 assert(min_young_length < max_young_length,
686 "otherwise we should have discovered that max_young_length "
687 "fits into the pause target and not done the binary search");
688 assert(predict_will_fit(min_young_length, base_time_ms,
689 base_free_regions, target_pause_time_ms),
690 "min_young_length, the result of the binary search, should "
691 "fit into the pause target");
692 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
693 base_free_regions, target_pause_time_ms),
694 "min_young_length, the result of the binary search, should be "
695 "optimal, so no larger length should fit into the pause target");
696 }
697 } else {
698 // Even the minimum length doesn't fit into the pause time
699 // target, return it as the result nevertheless.
700 }
701 return base_min_length + min_young_length;
702 }
703
704 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
705 double survivor_regions_evac_time = 0.0;
706 for (HeapRegion * r = _recorded_survivor_head;
707 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
708 r = r->get_next_young_region()) {
709 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
710 }
711 return survivor_regions_evac_time;
712 }
713
714 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
715 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
716
717 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
718 if (rs_lengths > _rs_lengths_prediction) {
719 // add 10% to avoid having to recalculate often
720 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
721 update_young_list_target_length(rs_lengths_prediction);
722 }
723 }
724
725
726
727 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
728 bool is_tlab,
729 bool* gc_overhead_limit_was_exceeded) {
730 guarantee(false, "Not using this policy feature yet.");
731 return NULL;
732 }
733
734 // This method controls how a collector handles one or more
735 // of its generations being fully allocated.
736 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
737 bool is_tlab) {
738 guarantee(false, "Not using this policy feature yet.");
739 return NULL;
740 }
741
742
743 #ifndef PRODUCT
744 bool G1CollectorPolicy::verify_young_ages() {
745 HeapRegion* head = _g1->young_list()->first_region();
746 return
747 verify_young_ages(head, _short_lived_surv_rate_group);
748 // also call verify_young_ages on any additional surv rate groups
749 }
750
751 bool
752 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
753 SurvRateGroup *surv_rate_group) {
754 guarantee( surv_rate_group != NULL, "pre-condition" );
755
756 const char* name = surv_rate_group->name();
757 bool ret = true;
758 int prev_age = -1;
759
760 for (HeapRegion* curr = head;
761 curr != NULL;
762 curr = curr->get_next_young_region()) {
763 SurvRateGroup* group = curr->surv_rate_group();
764 if (group == NULL && !curr->is_survivor()) {
765 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
766 ret = false;
767 }
768
769 if (surv_rate_group == group) {
770 int age = curr->age_in_surv_rate_group();
771
772 if (age < 0) {
773 gclog_or_tty->print_cr("## %s: encountered negative age", name);
774 ret = false;
775 }
776
777 if (age <= prev_age) {
778 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
779 "(%d, %d)", name, age, prev_age);
780 ret = false;
781 }
782 prev_age = age;
783 }
784 }
785
786 return ret;
787 }
788 #endif // PRODUCT
789
790 void G1CollectorPolicy::record_full_collection_start() {
791 _full_collection_start_sec = os::elapsedTime();
792 record_heap_size_info_at_start(true /* full */);
793 // Release the future to-space so that it is available for compaction into.
794 _g1->set_full_collection();
795 }
796
797 void G1CollectorPolicy::record_full_collection_end() {
798 // Consider this like a collection pause for the purposes of allocation
799 // since last pause.
800 double end_sec = os::elapsedTime();
801 double full_gc_time_sec = end_sec - _full_collection_start_sec;
802 double full_gc_time_ms = full_gc_time_sec * 1000.0;
803
804 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
805
806 update_recent_gc_times(end_sec, full_gc_time_ms);
807
808 _g1->clear_full_collection();
809
810 // "Nuke" the heuristics that control the young/mixed GC
811 // transitions and make sure we start with young GCs after the Full GC.
812 set_gcs_are_young(true);
813 _last_young_gc = false;
814 clear_initiate_conc_mark_if_possible();
815 clear_during_initial_mark_pause();
816 _in_marking_window = false;
817 _in_marking_window_im = false;
818
819 _short_lived_surv_rate_group->start_adding_regions();
820 // also call this on any additional surv rate groups
821
822 record_survivor_regions(0, NULL, NULL);
823
824 _free_regions_at_end_of_collection = _g1->num_free_regions();
825 // Reset survivors SurvRateGroup.
826 _survivor_surv_rate_group->reset();
827 update_young_list_target_length();
828 _collectionSetChooser->clear();
829 }
830
831 void G1CollectorPolicy::record_stop_world_start() {
832 _stop_world_start = os::elapsedTime();
833 }
834
835 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
836 // We only need to do this here as the policy will only be applied
837 // to the GC we're about to start. so, no point is calculating this
838 // every time we calculate / recalculate the target young length.
839 update_survivors_policy();
840
841 assert(_g1->used() == _g1->recalculate_used(),
842 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
843 _g1->used(), _g1->recalculate_used()));
844
845 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
846 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
847 _stop_world_start = 0.0;
848
849 record_heap_size_info_at_start(false /* full */);
850
851 phase_times()->record_cur_collection_start_sec(start_time_sec);
852 _pending_cards = _g1->pending_card_num();
853
854 _collection_set_bytes_used_before = 0;
855 _bytes_copied_during_gc = 0;
856
857 _last_gc_was_young = false;
858
859 // do that for any other surv rate groups
860 _short_lived_surv_rate_group->stop_adding_regions();
861 _survivors_age_table.clear();
862
863 assert( verify_young_ages(), "region age verification" );
864 }
865
866 void G1CollectorPolicy::record_concurrent_mark_init_end(double
867 mark_init_elapsed_time_ms) {
868 _during_marking = true;
869 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
870 clear_during_initial_mark_pause();
871 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
872 }
873
874 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
875 _mark_remark_start_sec = os::elapsedTime();
876 _during_marking = false;
877 }
878
879 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
880 double end_time_sec = os::elapsedTime();
881 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
882 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
883 _cur_mark_stop_world_time_ms += elapsed_time_ms;
884 _prev_collection_pause_end_ms += elapsed_time_ms;
885
886 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
887 }
888
889 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
890 _mark_cleanup_start_sec = os::elapsedTime();
891 }
892
893 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
894 _last_young_gc = true;
895 _in_marking_window = false;
896 }
897
898 void G1CollectorPolicy::record_concurrent_pause() {
899 if (_stop_world_start > 0.0) {
900 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
901 _trace_young_gen_time_data.record_yield_time(yield_ms);
902 }
903 }
904
905 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
906 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
907 return false;
908 }
909
910 size_t marking_initiating_used_threshold =
911 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
912 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
913 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
914
915 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
916 if (gcs_are_young() && !_last_young_gc) {
917 ergo_verbose5(ErgoConcCycles,
918 "request concurrent cycle initiation",
919 ergo_format_reason("occupancy higher than threshold")
920 ergo_format_byte("occupancy")
921 ergo_format_byte("allocation request")
922 ergo_format_byte_perc("threshold")
923 ergo_format_str("source"),
924 cur_used_bytes,
925 alloc_byte_size,
926 marking_initiating_used_threshold,
927 (double) InitiatingHeapOccupancyPercent,
928 source);
929 return true;
930 } else {
931 ergo_verbose5(ErgoConcCycles,
932 "do not request concurrent cycle initiation",
933 ergo_format_reason("still doing mixed collections")
934 ergo_format_byte("occupancy")
935 ergo_format_byte("allocation request")
936 ergo_format_byte_perc("threshold")
937 ergo_format_str("source"),
938 cur_used_bytes,
939 alloc_byte_size,
940 marking_initiating_used_threshold,
941 (double) InitiatingHeapOccupancyPercent,
942 source);
943 }
944 }
945
946 return false;
947 }
948
949 // Anything below that is considered to be zero
950 #define MIN_TIMER_GRANULARITY 0.0000001
951
952 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
953 double end_time_sec = os::elapsedTime();
954 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
955 "otherwise, the subtraction below does not make sense");
956 size_t rs_size =
957 _cur_collection_pause_used_regions_at_start - cset_region_length();
958 size_t cur_used_bytes = _g1->used();
959 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
960 bool last_pause_included_initial_mark = false;
961 bool update_stats = !_g1->evacuation_failed();
962
963 #ifndef PRODUCT
964 if (G1YoungSurvRateVerbose) {
965 gclog_or_tty->cr();
966 _short_lived_surv_rate_group->print();
967 // do that for any other surv rate groups too
968 }
969 #endif // PRODUCT
970
971 last_pause_included_initial_mark = during_initial_mark_pause();
972 if (last_pause_included_initial_mark) {
973 record_concurrent_mark_init_end(0.0);
974 } else if (need_to_start_conc_mark("end of GC")) {
975 // Note: this might have already been set, if during the last
976 // pause we decided to start a cycle but at the beginning of
977 // this pause we decided to postpone it. That's OK.
978 set_initiate_conc_mark_if_possible();
979 }
980
981 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
982 end_time_sec, false);
983
984 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
985 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
986
987 if (update_stats) {
988 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
989 // this is where we update the allocation rate of the application
990 double app_time_ms =
991 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
992 if (app_time_ms < MIN_TIMER_GRANULARITY) {
993 // This usually happens due to the timer not having the required
994 // granularity. Some Linuxes are the usual culprits.
995 // We'll just set it to something (arbitrarily) small.
996 app_time_ms = 1.0;
997 }
998 // We maintain the invariant that all objects allocated by mutator
999 // threads will be allocated out of eden regions. So, we can use
1000 // the eden region number allocated since the previous GC to
1001 // calculate the application's allocate rate. The only exception
1002 // to that is humongous objects that are allocated separately. But
1003 // given that humongous object allocations do not really affect
1004 // either the pause's duration nor when the next pause will take
1005 // place we can safely ignore them here.
1006 uint regions_allocated = eden_cset_region_length();
1007 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1008 _alloc_rate_ms_seq->add(alloc_rate_ms);
1009
1010 double interval_ms =
1011 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1012 update_recent_gc_times(end_time_sec, pause_time_ms);
1013 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1014 if (recent_avg_pause_time_ratio() < 0.0 ||
1015 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1016 #ifndef PRODUCT
1017 // Dump info to allow post-facto debugging
1018 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1019 gclog_or_tty->print_cr("-------------------------------------------");
1020 gclog_or_tty->print_cr("Recent GC Times (ms):");
1021 _recent_gc_times_ms->dump();
1022 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1023 _recent_prev_end_times_for_all_gcs_sec->dump();
1024 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1025 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1026 // In debug mode, terminate the JVM if the user wants to debug at this point.
1027 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1028 #endif // !PRODUCT
1029 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1030 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1031 if (_recent_avg_pause_time_ratio < 0.0) {
1032 _recent_avg_pause_time_ratio = 0.0;
1033 } else {
1034 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1035 _recent_avg_pause_time_ratio = 1.0;
1036 }
1037 }
1038 }
1039
1040 bool new_in_marking_window = _in_marking_window;
1041 bool new_in_marking_window_im = false;
1042 if (last_pause_included_initial_mark) {
1043 new_in_marking_window = true;
1044 new_in_marking_window_im = true;
1045 }
1046
1047 if (_last_young_gc) {
1048 // This is supposed to to be the "last young GC" before we start
1049 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1050
1051 if (!last_pause_included_initial_mark) {
1052 if (next_gc_should_be_mixed("start mixed GCs",
1053 "do not start mixed GCs")) {
1054 set_gcs_are_young(false);
1055 }
1056 } else {
1057 ergo_verbose0(ErgoMixedGCs,
1058 "do not start mixed GCs",
1059 ergo_format_reason("concurrent cycle is about to start"));
1060 }
1061 _last_young_gc = false;
1062 }
1063
1064 if (!_last_gc_was_young) {
1065 // This is a mixed GC. Here we decide whether to continue doing
1066 // mixed GCs or not.
1067
1068 if (!next_gc_should_be_mixed("continue mixed GCs",
1069 "do not continue mixed GCs")) {
1070 set_gcs_are_young(true);
1071 }
1072 }
1073
1074 _short_lived_surv_rate_group->start_adding_regions();
1075 // Do that for any other surv rate groups
1076
1077 if (update_stats) {
1078 double cost_per_card_ms = 0.0;
1079 if (_pending_cards > 0) {
1080 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1081 _cost_per_card_ms_seq->add(cost_per_card_ms);
1082 }
1083
1084 size_t cards_scanned = _g1->cards_scanned();
1085
1086 double cost_per_entry_ms = 0.0;
1087 if (cards_scanned > 10) {
1088 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1089 if (_last_gc_was_young) {
1090 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1091 } else {
1092 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1093 }
1094 }
1095
1096 if (_max_rs_lengths > 0) {
1097 double cards_per_entry_ratio =
1098 (double) cards_scanned / (double) _max_rs_lengths;
1099 if (_last_gc_was_young) {
1100 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1101 } else {
1102 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1103 }
1104 }
1105
1106 // This is defensive. For a while _max_rs_lengths could get
1107 // smaller than _recorded_rs_lengths which was causing
1108 // rs_length_diff to get very large and mess up the RSet length
1109 // predictions. The reason was unsafe concurrent updates to the
1110 // _inc_cset_recorded_rs_lengths field which the code below guards
1111 // against (see CR 7118202). This bug has now been fixed (see CR
1112 // 7119027). However, I'm still worried that
1113 // _inc_cset_recorded_rs_lengths might still end up somewhat
1114 // inaccurate. The concurrent refinement thread calculates an
1115 // RSet's length concurrently with other CR threads updating it
1116 // which might cause it to calculate the length incorrectly (if,
1117 // say, it's in mid-coarsening). So I'll leave in the defensive
1118 // conditional below just in case.
1119 size_t rs_length_diff = 0;
1120 if (_max_rs_lengths > _recorded_rs_lengths) {
1121 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1122 }
1123 _rs_length_diff_seq->add((double) rs_length_diff);
1124
1125 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1126 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1127 double cost_per_byte_ms = 0.0;
1128
1129 if (copied_bytes > 0) {
1130 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1131 if (_in_marking_window) {
1132 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1133 } else {
1134 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1135 }
1136 }
1137
1138 double all_other_time_ms = pause_time_ms -
1139 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1140 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1141
1142 double young_other_time_ms = 0.0;
1143 if (young_cset_region_length() > 0) {
1144 young_other_time_ms =
1145 phase_times()->young_cset_choice_time_ms() +
1146 phase_times()->young_free_cset_time_ms();
1147 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1148 (double) young_cset_region_length());
1149 }
1150 double non_young_other_time_ms = 0.0;
1151 if (old_cset_region_length() > 0) {
1152 non_young_other_time_ms =
1153 phase_times()->non_young_cset_choice_time_ms() +
1154 phase_times()->non_young_free_cset_time_ms();
1155
1156 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1157 (double) old_cset_region_length());
1158 }
1159
1160 double constant_other_time_ms = all_other_time_ms -
1161 (young_other_time_ms + non_young_other_time_ms);
1162 _constant_other_time_ms_seq->add(constant_other_time_ms);
1163
1164 double survival_ratio = 0.0;
1165 if (_collection_set_bytes_used_before > 0) {
1166 survival_ratio = (double) _bytes_copied_during_gc /
1167 (double) _collection_set_bytes_used_before;
1168 }
1169
1170 _pending_cards_seq->add((double) _pending_cards);
1171 _rs_lengths_seq->add((double) _max_rs_lengths);
1172 }
1173
1174 _in_marking_window = new_in_marking_window;
1175 _in_marking_window_im = new_in_marking_window_im;
1176 _free_regions_at_end_of_collection = _g1->num_free_regions();
1177 update_young_list_target_length();
1178
1179 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1180 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1181 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1182 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1183
1184 _collectionSetChooser->verify();
1185 }
1186
1187 #define EXT_SIZE_FORMAT "%.1f%s"
1188 #define EXT_SIZE_PARAMS(bytes) \
1189 byte_size_in_proper_unit((double)(bytes)), \
1190 proper_unit_for_byte_size((bytes))
1191
1192 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1193 YoungList* young_list = _g1->young_list();
1194 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1195 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1196 _heap_capacity_bytes_before_gc = _g1->capacity();
1197 _heap_used_bytes_before_gc = _g1->used();
1198 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1199
1200 _eden_capacity_bytes_before_gc =
1201 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1202
1203 if (full) {
1204 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1205 }
1206 }
1207
1208 void G1CollectorPolicy::print_heap_transition() {
1209 _g1->print_size_transition(gclog_or_tty,
1210 _heap_used_bytes_before_gc,
1211 _g1->used(),
1212 _g1->capacity());
1213 }
1214
1215 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {
1216 YoungList* young_list = _g1->young_list();
1217
1218 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1219 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1220 size_t heap_used_bytes_after_gc = _g1->used();
1221
1222 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1223 size_t eden_capacity_bytes_after_gc =
1224 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1225
1226 gclog_or_tty->print(
1227 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1228 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1229 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1230 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1231 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1232 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1233 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1234 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1235 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1236 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1237 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1238 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1239 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1240 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1241
1242 if (full) {
1243 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1244 }
1245
1246 gclog_or_tty->cr();
1247 }
1248
1249 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1250 double update_rs_processed_buffers,
1251 double goal_ms) {
1252 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1253 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1254
1255 if (G1UseAdaptiveConcRefinement) {
1256 const int k_gy = 3, k_gr = 6;
1257 const double inc_k = 1.1, dec_k = 0.9;
1258
1259 int g = cg1r->green_zone();
1260 if (update_rs_time > goal_ms) {
1261 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1262 } else {
1263 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1264 g = (int)MAX2(g * inc_k, g + 1.0);
1265 }
1266 }
1267 // Change the refinement threads params
1268 cg1r->set_green_zone(g);
1269 cg1r->set_yellow_zone(g * k_gy);
1270 cg1r->set_red_zone(g * k_gr);
1271 cg1r->reinitialize_threads();
1272
1273 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1274 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1275 cg1r->yellow_zone());
1276 // Change the barrier params
1277 dcqs.set_process_completed_threshold(processing_threshold);
1278 dcqs.set_max_completed_queue(cg1r->red_zone());
1279 }
1280
1281 int curr_queue_size = dcqs.completed_buffers_num();
1282 if (curr_queue_size >= cg1r->yellow_zone()) {
1283 dcqs.set_completed_queue_padding(curr_queue_size);
1284 } else {
1285 dcqs.set_completed_queue_padding(0);
1286 }
1287 dcqs.notify_if_necessary();
1288 }
1289
1290 double
1291 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1292 size_t scanned_cards) {
1293 return
1294 predict_rs_update_time_ms(pending_cards) +
1295 predict_rs_scan_time_ms(scanned_cards) +
1296 predict_constant_other_time_ms();
1297 }
1298
1299 double
1300 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1301 size_t rs_length = predict_rs_length_diff();
1302 size_t card_num;
1303 if (gcs_are_young()) {
1304 card_num = predict_young_card_num(rs_length);
1305 } else {
1306 card_num = predict_non_young_card_num(rs_length);
1307 }
1308 return predict_base_elapsed_time_ms(pending_cards, card_num);
1309 }
1310
1311 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1312 size_t bytes_to_copy;
1313 if (hr->is_marked())
1314 bytes_to_copy = hr->max_live_bytes();
1315 else {
1316 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1317 int age = hr->age_in_surv_rate_group();
1318 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1319 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1320 }
1321 return bytes_to_copy;
1322 }
1323
1324 double
1325 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1326 bool for_young_gc) {
1327 size_t rs_length = hr->rem_set()->occupied();
1328 size_t card_num;
1329
1330 // Predicting the number of cards is based on which type of GC
1331 // we're predicting for.
1332 if (for_young_gc) {
1333 card_num = predict_young_card_num(rs_length);
1334 } else {
1335 card_num = predict_non_young_card_num(rs_length);
1336 }
1337 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1338
1339 double region_elapsed_time_ms =
1340 predict_rs_scan_time_ms(card_num) +
1341 predict_object_copy_time_ms(bytes_to_copy);
1342
1343 // The prediction of the "other" time for this region is based
1344 // upon the region type and NOT the GC type.
1345 if (hr->is_young()) {
1346 region_elapsed_time_ms += predict_young_other_time_ms(1);
1347 } else {
1348 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1349 }
1350 return region_elapsed_time_ms;
1351 }
1352
1353 void
1354 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1355 uint survivor_cset_region_length) {
1356 _eden_cset_region_length = eden_cset_region_length;
1357 _survivor_cset_region_length = survivor_cset_region_length;
1358 _old_cset_region_length = 0;
1359 }
1360
1361 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1362 _recorded_rs_lengths = rs_lengths;
1363 }
1364
1365 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1366 double elapsed_ms) {
1367 _recent_gc_times_ms->add(elapsed_ms);
1368 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1369 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1370 }
1371
1372 size_t G1CollectorPolicy::expansion_amount() {
1373 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1374 double threshold = _gc_overhead_perc;
1375 if (recent_gc_overhead > threshold) {
1376 // We will double the existing space, or take
1377 // G1ExpandByPercentOfAvailable % of the available expansion
1378 // space, whichever is smaller, bounded below by a minimum
1379 // expansion (unless that's all that's left.)
1380 const size_t min_expand_bytes = 1*M;
1381 size_t reserved_bytes = _g1->max_capacity();
1382 size_t committed_bytes = _g1->capacity();
1383 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1384 size_t expand_bytes;
1385 size_t expand_bytes_via_pct =
1386 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1387 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1388 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1389 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1390
1391 ergo_verbose5(ErgoHeapSizing,
1392 "attempt heap expansion",
1393 ergo_format_reason("recent GC overhead higher than "
1394 "threshold after GC")
1395 ergo_format_perc("recent GC overhead")
1396 ergo_format_perc("threshold")
1397 ergo_format_byte("uncommitted")
1398 ergo_format_byte_perc("calculated expansion amount"),
1399 recent_gc_overhead, threshold,
1400 uncommitted_bytes,
1401 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1402
1403 return expand_bytes;
1404 } else {
1405 return 0;
1406 }
1407 }
1408
1409 void G1CollectorPolicy::print_tracing_info() const {
1410 _trace_young_gen_time_data.print();
1411 _trace_old_gen_time_data.print();
1412 }
1413
1414 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1415 #ifndef PRODUCT
1416 _short_lived_surv_rate_group->print_surv_rate_summary();
1417 // add this call for any other surv rate groups
1418 #endif // PRODUCT
1419 }
1420
1421 bool G1CollectorPolicy::is_young_list_full() {
1422 uint young_list_length = _g1->young_list()->length();
1423 uint young_list_target_length = _young_list_target_length;
1424 return young_list_length >= young_list_target_length;
1425 }
1426
1427 bool G1CollectorPolicy::can_expand_young_list() {
1428 uint young_list_length = _g1->young_list()->length();
1429 uint young_list_max_length = _young_list_max_length;
1430 return young_list_length < young_list_max_length;
1431 }
1432
1433 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1434 uint expansion_region_num = 0;
1435 if (GCLockerEdenExpansionPercent > 0) {
1436 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1437 double expansion_region_num_d = perc * (double) _young_list_target_length;
1438 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1439 // less than 1.0) we'll get 1.
1440 expansion_region_num = (uint) ceil(expansion_region_num_d);
1441 } else {
1442 assert(expansion_region_num == 0, "sanity");
1443 }
1444 _young_list_max_length = _young_list_target_length + expansion_region_num;
1445 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1446 }
1447
1448 // Calculates survivor space parameters.
1449 void G1CollectorPolicy::update_survivors_policy() {
1450 double max_survivor_regions_d =
1451 (double) _young_list_target_length / (double) SurvivorRatio;
1452 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1453 // smaller than 1.0) we'll get 1.
1454 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1455
1456 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1457 HeapRegion::GrainWords * _max_survivor_regions);
1458 }
1459
1460 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1461 GCCause::Cause gc_cause) {
1462 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1463 if (!during_cycle) {
1464 ergo_verbose1(ErgoConcCycles,
1465 "request concurrent cycle initiation",
1466 ergo_format_reason("requested by GC cause")
1467 ergo_format_str("GC cause"),
1468 GCCause::to_string(gc_cause));
1469 set_initiate_conc_mark_if_possible();
1470 return true;
1471 } else {
1472 ergo_verbose1(ErgoConcCycles,
1473 "do not request concurrent cycle initiation",
1474 ergo_format_reason("concurrent cycle already in progress")
1475 ergo_format_str("GC cause"),
1476 GCCause::to_string(gc_cause));
1477 return false;
1478 }
1479 }
1480
1481 void
1482 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1483 // We are about to decide on whether this pause will be an
1484 // initial-mark pause.
1485
1486 // First, during_initial_mark_pause() should not be already set. We
1487 // will set it here if we have to. However, it should be cleared by
1488 // the end of the pause (it's only set for the duration of an
1489 // initial-mark pause).
1490 assert(!during_initial_mark_pause(), "pre-condition");
1491
1492 if (initiate_conc_mark_if_possible()) {
1493 // We had noticed on a previous pause that the heap occupancy has
1494 // gone over the initiating threshold and we should start a
1495 // concurrent marking cycle. So we might initiate one.
1496
1497 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1498 if (!during_cycle) {
1499 // The concurrent marking thread is not "during a cycle", i.e.,
1500 // it has completed the last one. So we can go ahead and
1501 // initiate a new cycle.
1502
1503 set_during_initial_mark_pause();
1504 // We do not allow mixed GCs during marking.
1505 if (!gcs_are_young()) {
1506 set_gcs_are_young(true);
1507 ergo_verbose0(ErgoMixedGCs,
1508 "end mixed GCs",
1509 ergo_format_reason("concurrent cycle is about to start"));
1510 }
1511
1512 // And we can now clear initiate_conc_mark_if_possible() as
1513 // we've already acted on it.
1514 clear_initiate_conc_mark_if_possible();
1515
1516 ergo_verbose0(ErgoConcCycles,
1517 "initiate concurrent cycle",
1518 ergo_format_reason("concurrent cycle initiation requested"));
1519 } else {
1520 // The concurrent marking thread is still finishing up the
1521 // previous cycle. If we start one right now the two cycles
1522 // overlap. In particular, the concurrent marking thread might
1523 // be in the process of clearing the next marking bitmap (which
1524 // we will use for the next cycle if we start one). Starting a
1525 // cycle now will be bad given that parts of the marking
1526 // information might get cleared by the marking thread. And we
1527 // cannot wait for the marking thread to finish the cycle as it
1528 // periodically yields while clearing the next marking bitmap
1529 // and, if it's in a yield point, it's waiting for us to
1530 // finish. So, at this point we will not start a cycle and we'll
1531 // let the concurrent marking thread complete the last one.
1532 ergo_verbose0(ErgoConcCycles,
1533 "do not initiate concurrent cycle",
1534 ergo_format_reason("concurrent cycle already in progress"));
1535 }
1536 }
1537 }
1538
1539 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1540 G1CollectedHeap* _g1h;
1541 CSetChooserParUpdater _cset_updater;
1542
1543 public:
1544 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1545 uint chunk_size) :
1546 _g1h(G1CollectedHeap::heap()),
1547 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1548
1549 bool doHeapRegion(HeapRegion* r) {
1550 // Do we have any marking information for this region?
1551 if (r->is_marked()) {
1552 // We will skip any region that's currently used as an old GC
1553 // alloc region (we should not consider those for collection
1554 // before we fill them up).
1555 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1556 _cset_updater.add_region(r);
1557 }
1558 }
1559 return false;
1560 }
1561 };
1562
1563 class ParKnownGarbageTask: public AbstractGangTask {
1564 CollectionSetChooser* _hrSorted;
1565 uint _chunk_size;
1566 G1CollectedHeap* _g1;
1567 HeapRegionClaimer _hrclaimer;
1568
1569 public:
1570 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1571 AbstractGangTask("ParKnownGarbageTask"),
1572 _hrSorted(hrSorted), _chunk_size(chunk_size),
1573 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1574
1575 void work(uint worker_id) {
1576 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1577 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1578 }
1579 };
1580
1581 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) {
1582 assert(n_workers > 0, "Active gc workers should be greater than 0");
1583 const uint overpartition_factor = 4;
1584 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1585 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1586 }
1587
1588 void
1589 G1CollectorPolicy::record_concurrent_mark_cleanup_end(uint n_workers) {
1590 _collectionSetChooser->clear();
1591
1592 uint n_regions = _g1->num_regions();
1593 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1594 _collectionSetChooser->prepare_for_par_region_addition(n_regions, chunk_size);
1595 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1596 _g1->workers()->run_task(&par_known_garbage_task);
1597
1598 _collectionSetChooser->sort_regions();
1599
1600 double end_sec = os::elapsedTime();
1601 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1602 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1603 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1604 _prev_collection_pause_end_ms += elapsed_time_ms;
1605 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1606 }
1607
1608 // Add the heap region at the head of the non-incremental collection set
1609 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1610 assert(_inc_cset_build_state == Active, "Precondition");
1611 assert(hr->is_old(), "the region should be old");
1612
1613 assert(!hr->in_collection_set(), "should not already be in the CSet");
1614 hr->set_in_collection_set(true);
1615 hr->set_next_in_collection_set(_collection_set);
1616 _collection_set = hr;
1617 _collection_set_bytes_used_before += hr->used();
1618 _g1->register_old_region_with_in_cset_fast_test(hr);
1619 size_t rs_length = hr->rem_set()->occupied();
1620 _recorded_rs_lengths += rs_length;
1621 _old_cset_region_length += 1;
1622 }
1623
1624 // Initialize the per-collection-set information
1625 void G1CollectorPolicy::start_incremental_cset_building() {
1626 assert(_inc_cset_build_state == Inactive, "Precondition");
1627
1628 _inc_cset_head = NULL;
1629 _inc_cset_tail = NULL;
1630 _inc_cset_bytes_used_before = 0;
1631
1632 _inc_cset_max_finger = 0;
1633 _inc_cset_recorded_rs_lengths = 0;
1634 _inc_cset_recorded_rs_lengths_diffs = 0;
1635 _inc_cset_predicted_elapsed_time_ms = 0.0;
1636 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1637 _inc_cset_build_state = Active;
1638 }
1639
1640 void G1CollectorPolicy::finalize_incremental_cset_building() {
1641 assert(_inc_cset_build_state == Active, "Precondition");
1642 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1643
1644 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1645 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1646 // that adds a new region to the CSet. Further updates by the
1647 // concurrent refinement thread that samples the young RSet lengths
1648 // are accumulated in the *_diffs fields. Here we add the diffs to
1649 // the "main" fields.
1650
1651 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1652 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1653 } else {
1654 // This is defensive. The diff should in theory be always positive
1655 // as RSets can only grow between GCs. However, given that we
1656 // sample their size concurrently with other threads updating them
1657 // it's possible that we might get the wrong size back, which
1658 // could make the calculations somewhat inaccurate.
1659 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1660 if (_inc_cset_recorded_rs_lengths >= diffs) {
1661 _inc_cset_recorded_rs_lengths -= diffs;
1662 } else {
1663 _inc_cset_recorded_rs_lengths = 0;
1664 }
1665 }
1666 _inc_cset_predicted_elapsed_time_ms +=
1667 _inc_cset_predicted_elapsed_time_ms_diffs;
1668
1669 _inc_cset_recorded_rs_lengths_diffs = 0;
1670 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1671 }
1672
1673 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1674 // This routine is used when:
1675 // * adding survivor regions to the incremental cset at the end of an
1676 // evacuation pause,
1677 // * adding the current allocation region to the incremental cset
1678 // when it is retired, and
1679 // * updating existing policy information for a region in the
1680 // incremental cset via young list RSet sampling.
1681 // Therefore this routine may be called at a safepoint by the
1682 // VM thread, or in-between safepoints by mutator threads (when
1683 // retiring the current allocation region) or a concurrent
1684 // refine thread (RSet sampling).
1685
1686 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1687 size_t used_bytes = hr->used();
1688 _inc_cset_recorded_rs_lengths += rs_length;
1689 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1690 _inc_cset_bytes_used_before += used_bytes;
1691
1692 // Cache the values we have added to the aggregated information
1693 // in the heap region in case we have to remove this region from
1694 // the incremental collection set, or it is updated by the
1695 // rset sampling code
1696 hr->set_recorded_rs_length(rs_length);
1697 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1698 }
1699
1700 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1701 size_t new_rs_length) {
1702 // Update the CSet information that is dependent on the new RS length
1703 assert(hr->is_young(), "Precondition");
1704 assert(!SafepointSynchronize::is_at_safepoint(),
1705 "should not be at a safepoint");
1706
1707 // We could have updated _inc_cset_recorded_rs_lengths and
1708 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1709 // that atomically, as this code is executed by a concurrent
1710 // refinement thread, potentially concurrently with a mutator thread
1711 // allocating a new region and also updating the same fields. To
1712 // avoid the atomic operations we accumulate these updates on two
1713 // separate fields (*_diffs) and we'll just add them to the "main"
1714 // fields at the start of a GC.
1715
1716 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1717 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1718 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1719
1720 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1721 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1722 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1723 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1724
1725 hr->set_recorded_rs_length(new_rs_length);
1726 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1727 }
1728
1729 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1730 assert(hr->is_young(), "invariant");
1731 assert(hr->young_index_in_cset() > -1, "should have already been set");
1732 assert(_inc_cset_build_state == Active, "Precondition");
1733
1734 // We need to clear and set the cached recorded/cached collection set
1735 // information in the heap region here (before the region gets added
1736 // to the collection set). An individual heap region's cached values
1737 // are calculated, aggregated with the policy collection set info,
1738 // and cached in the heap region here (initially) and (subsequently)
1739 // by the Young List sampling code.
1740
1741 size_t rs_length = hr->rem_set()->occupied();
1742 add_to_incremental_cset_info(hr, rs_length);
1743
1744 HeapWord* hr_end = hr->end();
1745 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1746
1747 assert(!hr->in_collection_set(), "invariant");
1748 hr->set_in_collection_set(true);
1749 assert( hr->next_in_collection_set() == NULL, "invariant");
1750
1751 _g1->register_young_region_with_in_cset_fast_test(hr);
1752 }
1753
1754 // Add the region at the RHS of the incremental cset
1755 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1756 // We should only ever be appending survivors at the end of a pause
1757 assert(hr->is_survivor(), "Logic");
1758
1759 // Do the 'common' stuff
1760 add_region_to_incremental_cset_common(hr);
1761
1762 // Now add the region at the right hand side
1763 if (_inc_cset_tail == NULL) {
1764 assert(_inc_cset_head == NULL, "invariant");
1765 _inc_cset_head = hr;
1766 } else {
1767 _inc_cset_tail->set_next_in_collection_set(hr);
1768 }
1769 _inc_cset_tail = hr;
1770 }
1771
1772 // Add the region to the LHS of the incremental cset
1773 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1774 // Survivors should be added to the RHS at the end of a pause
1775 assert(hr->is_eden(), "Logic");
1776
1777 // Do the 'common' stuff
1778 add_region_to_incremental_cset_common(hr);
1779
1780 // Add the region at the left hand side
1781 hr->set_next_in_collection_set(_inc_cset_head);
1782 if (_inc_cset_head == NULL) {
1783 assert(_inc_cset_tail == NULL, "Invariant");
1784 _inc_cset_tail = hr;
1785 }
1786 _inc_cset_head = hr;
1787 }
1788
1789 #ifndef PRODUCT
1790 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1791 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1792
1793 st->print_cr("\nCollection_set:");
1794 HeapRegion* csr = list_head;
1795 while (csr != NULL) {
1796 HeapRegion* next = csr->next_in_collection_set();
1797 assert(csr->in_collection_set(), "bad CS");
1798 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1799 HR_FORMAT_PARAMS(csr),
1800 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1801 csr->age_in_surv_rate_group_cond());
1802 csr = next;
1803 }
1804 }
1805 #endif // !PRODUCT
1806
1807 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1808 // Returns the given amount of reclaimable bytes (that represents
1809 // the amount of reclaimable space still to be collected) as a
1810 // percentage of the current heap capacity.
1811 size_t capacity_bytes = _g1->capacity();
1812 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1813 }
1814
1815 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1816 const char* false_action_str) {
1817 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1818 if (cset_chooser->is_empty()) {
1819 ergo_verbose0(ErgoMixedGCs,
1820 false_action_str,
1821 ergo_format_reason("candidate old regions not available"));
1822 return false;
1823 }
1824
1825 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1826 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1827 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1828 double threshold = (double) G1HeapWastePercent;
1829 if (reclaimable_perc <= threshold) {
1830 ergo_verbose4(ErgoMixedGCs,
1831 false_action_str,
1832 ergo_format_reason("reclaimable percentage not over threshold")
1833 ergo_format_region("candidate old regions")
1834 ergo_format_byte_perc("reclaimable")
1835 ergo_format_perc("threshold"),
1836 cset_chooser->remaining_regions(),
1837 reclaimable_bytes,
1838 reclaimable_perc, threshold);
1839 return false;
1840 }
1841
1842 ergo_verbose4(ErgoMixedGCs,
1843 true_action_str,
1844 ergo_format_reason("candidate old regions available")
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 true;
1852 }
1853
1854 uint G1CollectorPolicy::calc_min_old_cset_length() {
1855 // The min old CSet region bound is based on the maximum desired
1856 // number of mixed GCs after a cycle. I.e., even if some old regions
1857 // look expensive, we should add them to the CSet anyway to make
1858 // sure we go through the available old regions in no more than the
1859 // maximum desired number of mixed GCs.
1860 //
1861 // The calculation is based on the number of marked regions we added
1862 // to the CSet chooser in the first place, not how many remain, so
1863 // that the result is the same during all mixed GCs that follow a cycle.
1864
1865 const size_t region_num = (size_t) _collectionSetChooser->length();
1866 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1867 size_t result = region_num / gc_num;
1868 // emulate ceiling
1869 if (result * gc_num < region_num) {
1870 result += 1;
1871 }
1872 return (uint) result;
1873 }
1874
1875 uint G1CollectorPolicy::calc_max_old_cset_length() {
1876 // The max old CSet region bound is based on the threshold expressed
1877 // as a percentage of the heap size. I.e., it should bound the
1878 // number of old regions added to the CSet irrespective of how many
1879 // of them are available.
1880
1881 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1882 const size_t region_num = g1h->num_regions();
1883 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1884 size_t result = region_num * perc / 100;
1885 // emulate ceiling
1886 if (100 * result < region_num * perc) {
1887 result += 1;
1888 }
1889 return (uint) result;
1890 }
1891
1892
1893 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1894 double young_start_time_sec = os::elapsedTime();
1895
1896 YoungList* young_list = _g1->young_list();
1897 finalize_incremental_cset_building();
1898
1899 guarantee(target_pause_time_ms > 0.0,
1900 err_msg("target_pause_time_ms = %1.6lf should be positive",
1901 target_pause_time_ms));
1902 guarantee(_collection_set == NULL, "Precondition");
1903
1904 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1905 double predicted_pause_time_ms = base_time_ms;
1906 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1907
1908 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1909 "start choosing CSet",
1910 ergo_format_size("_pending_cards")
1911 ergo_format_ms("predicted base time")
1912 ergo_format_ms("remaining time")
1913 ergo_format_ms("target pause time"),
1914 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1915
1916 _last_gc_was_young = gcs_are_young() ? true : false;
1917
1918 if (_last_gc_was_young) {
1919 _trace_young_gen_time_data.increment_young_collection_count();
1920 } else {
1921 _trace_young_gen_time_data.increment_mixed_collection_count();
1922 }
1923
1924 // The young list is laid with the survivor regions from the previous
1925 // pause are appended to the RHS of the young list, i.e.
1926 // [Newly Young Regions ++ Survivors from last pause].
1927
1928 uint survivor_region_length = young_list->survivor_length();
1929 uint eden_region_length = young_list->length() - survivor_region_length;
1930 init_cset_region_lengths(eden_region_length, survivor_region_length);
1931
1932 HeapRegion* hr = young_list->first_survivor_region();
1933 while (hr != NULL) {
1934 assert(hr->is_survivor(), "badly formed young list");
1935 // There is a convention that all the young regions in the CSet
1936 // are tagged as "eden", so we do this for the survivors here. We
1937 // use the special set_eden_pre_gc() as it doesn't check that the
1938 // region is free (which is not the case here).
1939 hr->set_eden_pre_gc();
1940 hr = hr->get_next_young_region();
1941 }
1942
1943 // Clear the fields that point to the survivor list - they are all young now.
1944 young_list->clear_survivors();
1945
1946 _collection_set = _inc_cset_head;
1947 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1948 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1949 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1950
1951 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1952 "add young regions to CSet",
1953 ergo_format_region("eden")
1954 ergo_format_region("survivors")
1955 ergo_format_ms("predicted young region time"),
1956 eden_region_length, survivor_region_length,
1957 _inc_cset_predicted_elapsed_time_ms);
1958
1959 // The number of recorded young regions is the incremental
1960 // collection set's current size
1961 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1962
1963 double young_end_time_sec = os::elapsedTime();
1964 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1965
1966 // Set the start of the non-young choice time.
1967 double non_young_start_time_sec = young_end_time_sec;
1968
1969 if (!gcs_are_young()) {
1970 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1971 cset_chooser->verify();
1972 const uint min_old_cset_length = calc_min_old_cset_length();
1973 const uint max_old_cset_length = calc_max_old_cset_length();
1974
1975 uint expensive_region_num = 0;
1976 bool check_time_remaining = adaptive_young_list_length();
1977
1978 HeapRegion* hr = cset_chooser->peek();
1979 while (hr != NULL) {
1980 if (old_cset_region_length() >= max_old_cset_length) {
1981 // Added maximum number of old regions to the CSet.
1982 ergo_verbose2(ErgoCSetConstruction,
1983 "finish adding old regions to CSet",
1984 ergo_format_reason("old CSet region num reached max")
1985 ergo_format_region("old")
1986 ergo_format_region("max"),
1987 old_cset_region_length(), max_old_cset_length);
1988 break;
1989 }
1990
1991
1992 // Stop adding regions if the remaining reclaimable space is
1993 // not above G1HeapWastePercent.
1994 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1995 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1996 double threshold = (double) G1HeapWastePercent;
1997 if (reclaimable_perc <= threshold) {
1998 // We've added enough old regions that the amount of uncollected
1999 // reclaimable space is at or below the waste threshold. Stop
2000 // adding old regions to the CSet.
2001 ergo_verbose5(ErgoCSetConstruction,
2002 "finish adding old regions to CSet",
2003 ergo_format_reason("reclaimable percentage not over threshold")
2004 ergo_format_region("old")
2005 ergo_format_region("max")
2006 ergo_format_byte_perc("reclaimable")
2007 ergo_format_perc("threshold"),
2008 old_cset_region_length(),
2009 max_old_cset_length,
2010 reclaimable_bytes,
2011 reclaimable_perc, threshold);
2012 break;
2013 }
2014
2015 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2016 if (check_time_remaining) {
2017 if (predicted_time_ms > time_remaining_ms) {
2018 // Too expensive for the current CSet.
2019
2020 if (old_cset_region_length() >= min_old_cset_length) {
2021 // We have added the minimum number of old regions to the CSet,
2022 // we are done with this CSet.
2023 ergo_verbose4(ErgoCSetConstruction,
2024 "finish adding old regions to CSet",
2025 ergo_format_reason("predicted time is too high")
2026 ergo_format_ms("predicted time")
2027 ergo_format_ms("remaining time")
2028 ergo_format_region("old")
2029 ergo_format_region("min"),
2030 predicted_time_ms, time_remaining_ms,
2031 old_cset_region_length(), min_old_cset_length);
2032 break;
2033 }
2034
2035 // We'll add it anyway given that we haven't reached the
2036 // minimum number of old regions.
2037 expensive_region_num += 1;
2038 }
2039 } else {
2040 if (old_cset_region_length() >= min_old_cset_length) {
2041 // In the non-auto-tuning case, we'll finish adding regions
2042 // to the CSet if we reach the minimum.
2043 ergo_verbose2(ErgoCSetConstruction,
2044 "finish adding old regions to CSet",
2045 ergo_format_reason("old CSet region num reached min")
2046 ergo_format_region("old")
2047 ergo_format_region("min"),
2048 old_cset_region_length(), min_old_cset_length);
2049 break;
2050 }
2051 }
2052
2053 // We will add this region to the CSet.
2054 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2055 predicted_pause_time_ms += predicted_time_ms;
2056 cset_chooser->remove_and_move_to_next(hr);
2057 _g1->old_set_remove(hr);
2058 add_old_region_to_cset(hr);
2059
2060 hr = cset_chooser->peek();
2061 }
2062 if (hr == NULL) {
2063 ergo_verbose0(ErgoCSetConstruction,
2064 "finish adding old regions to CSet",
2065 ergo_format_reason("candidate old regions not available"));
2066 }
2067
2068 if (expensive_region_num > 0) {
2069 // We print the information once here at the end, predicated on
2070 // whether we added any apparently expensive regions or not, to
2071 // avoid generating output per region.
2072 ergo_verbose4(ErgoCSetConstruction,
2073 "added expensive regions to CSet",
2074 ergo_format_reason("old CSet region num not reached min")
2075 ergo_format_region("old")
2076 ergo_format_region("expensive")
2077 ergo_format_region("min")
2078 ergo_format_ms("remaining time"),
2079 old_cset_region_length(),
2080 expensive_region_num,
2081 min_old_cset_length,
2082 time_remaining_ms);
2083 }
2084
2085 cset_chooser->verify();
2086 }
2087
2088 stop_incremental_cset_building();
2089
2090 ergo_verbose5(ErgoCSetConstruction,
2091 "finish choosing CSet",
2092 ergo_format_region("eden")
2093 ergo_format_region("survivors")
2094 ergo_format_region("old")
2095 ergo_format_ms("predicted pause time")
2096 ergo_format_ms("target pause time"),
2097 eden_region_length, survivor_region_length,
2098 old_cset_region_length(),
2099 predicted_pause_time_ms, target_pause_time_ms);
2100
2101 double non_young_end_time_sec = os::elapsedTime();
2102 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2103 evacuation_info.set_collectionset_regions(cset_region_length());
2104 }
2105
2106 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2107 if(TraceYoungGenTime) {
2108 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2109 }
2110 }
2111
2112 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2113 if(TraceYoungGenTime) {
2114 _all_yield_times_ms.add(yield_time_ms);
2115 }
2116 }
2117
2118 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2119 if(TraceYoungGenTime) {
2120 _total.add(pause_time_ms);
2121 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2122 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2123 _parallel.add(phase_times->cur_collection_par_time_ms());
2124 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2125 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2126 _update_rs.add(phase_times->average_last_update_rs_time());
2127 _scan_rs.add(phase_times->average_last_scan_rs_time());
2128 _obj_copy.add(phase_times->average_last_obj_copy_time());
2129 _termination.add(phase_times->average_last_termination_time());
2130
2131 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2132 phase_times->average_last_satb_filtering_times_ms() +
2133 phase_times->average_last_update_rs_time() +
2134 phase_times->average_last_scan_rs_time() +
2135 phase_times->average_last_obj_copy_time() +
2136 + phase_times->average_last_termination_time();
2137
2138 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2139 _parallel_other.add(parallel_other_time);
2140 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2141 }
2142 }
2143
2144 void TraceYoungGenTimeData::increment_young_collection_count() {
2145 if(TraceYoungGenTime) {
2146 ++_young_pause_num;
2147 }
2148 }
2149
2150 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2151 if(TraceYoungGenTime) {
2152 ++_mixed_pause_num;
2153 }
2154 }
2155
2156 void TraceYoungGenTimeData::print_summary(const char* str,
2157 const NumberSeq* seq) const {
2158 double sum = seq->sum();
2159 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2160 str, sum / 1000.0, seq->avg());
2161 }
2162
2163 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2164 const NumberSeq* seq) const {
2165 print_summary(str, seq);
2166 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2167 "(num", seq->num(), seq->sd(), seq->maximum());
2168 }
2169
2170 void TraceYoungGenTimeData::print() const {
2171 if (!TraceYoungGenTime) {
2172 return;
2173 }
2174
2175 gclog_or_tty->print_cr("ALL PAUSES");
2176 print_summary_sd(" Total", &_total);
2177 gclog_or_tty->cr();
2178 gclog_or_tty->cr();
2179 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2180 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2181 gclog_or_tty->cr();
2182
2183 gclog_or_tty->print_cr("EVACUATION PAUSES");
2184
2185 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2186 gclog_or_tty->print_cr("none");
2187 } else {
2188 print_summary_sd(" Evacuation Pauses", &_total);
2189 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2190 print_summary(" Parallel Time", &_parallel);
2191 print_summary(" Ext Root Scanning", &_ext_root_scan);
2192 print_summary(" SATB Filtering", &_satb_filtering);
2193 print_summary(" Update RS", &_update_rs);
2194 print_summary(" Scan RS", &_scan_rs);
2195 print_summary(" Object Copy", &_obj_copy);
2196 print_summary(" Termination", &_termination);
2197 print_summary(" Parallel Other", &_parallel_other);
2198 print_summary(" Clear CT", &_clear_ct);
2199 print_summary(" Other", &_other);
2200 }
2201 gclog_or_tty->cr();
2202
2203 gclog_or_tty->print_cr("MISC");
2204 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2205 print_summary_sd(" Yields", &_all_yield_times_ms);
2206 }
2207
2208 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2209 if (TraceOldGenTime) {
2210 _all_full_gc_times.add(full_gc_time_ms);
2211 }
2212 }
2213
2214 void TraceOldGenTimeData::print() const {
2215 if (!TraceOldGenTime) {
2216 return;
2217 }
2218
2219 if (_all_full_gc_times.num() > 0) {
2220 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2221 _all_full_gc_times.num(),
2222 _all_full_gc_times.sum() / 1000.0);
2223 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2224 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2225 _all_full_gc_times.sd(),
2226 _all_full_gc_times.maximum());
2227 }
2228 }