1 /*
2 * Copyright (c) 2001, 2014, 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 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
90 _stop_world_start(0.0),
91
92 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
93 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
94
95 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
96 _prev_collection_pause_end_ms(0.0),
97 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
104 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
105 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
106 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _non_young_other_cost_per_region_ms_seq(
108 new TruncatedSeq(TruncatedSeqLength)),
109
110 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
111 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
112
113 _pause_time_target_ms((double) MaxGCPauseMillis),
114
115 _gcs_are_young(true),
116
117 _during_marking(false),
118 _in_marking_window(false),
119 _in_marking_window_im(false),
120
121 _recent_prev_end_times_for_all_gcs_sec(
122 new TruncatedSeq(NumPrevPausesForHeuristics)),
123
124 _recent_avg_pause_time_ratio(0.0),
125
126 _initiate_conc_mark_if_possible(false),
127 _during_initial_mark_pause(false),
128 _last_young_gc(false),
129 _last_gc_was_young(false),
130
131 _eden_used_bytes_before_gc(0),
132 _survivor_used_bytes_before_gc(0),
133 _heap_used_bytes_before_gc(0),
134 _metaspace_used_bytes_before_gc(0),
135 _eden_capacity_bytes_before_gc(0),
136 _heap_capacity_bytes_before_gc(0),
137
138 _eden_cset_region_length(0),
139 _survivor_cset_region_length(0),
140 _old_cset_region_length(0),
141
142 _collection_set(NULL),
143 _collection_set_bytes_used_before(0),
144
145 // Incremental CSet attributes
146 _inc_cset_build_state(Inactive),
147 _inc_cset_head(NULL),
148 _inc_cset_tail(NULL),
149 _inc_cset_bytes_used_before(0),
150 _inc_cset_max_finger(NULL),
151 _inc_cset_recorded_rs_lengths(0),
152 _inc_cset_recorded_rs_lengths_diffs(0),
153 _inc_cset_predicted_elapsed_time_ms(0.0),
154 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
155
156 // add here any more surv rate groups
157 _recorded_survivor_regions(0),
158 _recorded_survivor_head(NULL),
159 _recorded_survivor_tail(NULL),
160 _survivors_age_table(true),
161
162 _gc_overhead_perc(0.0) {
163
164 uintx confidence_perc = G1ConfidencePercent;
165 // Put an artificial ceiling on this so that it's not set to a silly value.
166 if (confidence_perc > 100) {
167 confidence_perc = 100;
168 warning("G1ConfidencePercent is set to a value that is too large, "
169 "it's been updated to %u", confidence_perc);
170 }
171 // '_sigma' must be initialized before the SurvRateGroups below because they
172 // indirecty access '_sigma' trough the 'this' pointer in their constructor.
173 _sigma = (double) confidence_perc / 100.0;
174
175 _short_lived_surv_rate_group =
176 new SurvRateGroup(this, "Short Lived", G1YoungSurvRateNumRegionsSummary);
177 _survivor_surv_rate_group =
178 new SurvRateGroup(this, "Survivor", G1YoungSurvRateNumRegionsSummary);
179
180 // Set up the region size and associated fields. Given that the
181 // policy is created before the heap, we have to set this up here,
182 // so it's done as soon as possible.
183
184 // It would have been natural to pass initial_heap_byte_size() and
185 // max_heap_byte_size() to setup_heap_region_size() but those have
186 // not been set up at this point since they should be aligned with
187 // the region size. So, there is a circular dependency here. We base
188 // the region size on the heap size, but the heap size should be
189 // aligned with the region size. To get around this we use the
190 // unaligned values for the heap.
191 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
192 HeapRegionRemSet::setup_remset_size();
193
194 G1ErgoVerbose::initialize();
195 if (PrintAdaptiveSizePolicy) {
196 // Currently, we only use a single switch for all the heuristics.
197 G1ErgoVerbose::set_enabled(true);
198 // Given that we don't currently have a verboseness level
199 // parameter, we'll hardcode this to high. This can be easily
200 // changed in the future.
201 G1ErgoVerbose::set_level(ErgoHigh);
202 } else {
203 G1ErgoVerbose::set_enabled(false);
204 }
205
206 // Verify PLAB sizes
207 const size_t region_size = HeapRegion::GrainWords;
208 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
209 char buffer[128];
210 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
211 OldPLABSize > region_size ? "Old" : "Young", region_size);
212 vm_exit_during_initialization(buffer);
213 }
214
215 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
216 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
217
218 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
219
220 int index = MIN2(_parallel_gc_threads - 1, 7);
221
222 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
223 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
224 _young_cards_per_entry_ratio_seq->add(
225 young_cards_per_entry_ratio_defaults[index]);
226 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
227 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
228 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
229 _young_other_cost_per_region_ms_seq->add(
230 young_other_cost_per_region_ms_defaults[index]);
231 _non_young_other_cost_per_region_ms_seq->add(
232 non_young_other_cost_per_region_ms_defaults[index]);
233
234 // Below, we might need to calculate the pause time target based on
235 // the pause interval. When we do so we are going to give G1 maximum
236 // flexibility and allow it to do pauses when it needs to. So, we'll
237 // arrange that the pause interval to be pause time target + 1 to
238 // ensure that a) the pause time target is maximized with respect to
239 // the pause interval and b) we maintain the invariant that pause
240 // time target < pause interval. If the user does not want this
241 // maximum flexibility, they will have to set the pause interval
242 // explicitly.
243
244 // First make sure that, if either parameter is set, its value is
245 // reasonable.
246 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
247 if (MaxGCPauseMillis < 1) {
248 vm_exit_during_initialization("MaxGCPauseMillis should be "
249 "greater than 0");
250 }
251 }
252 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
253 if (GCPauseIntervalMillis < 1) {
254 vm_exit_during_initialization("GCPauseIntervalMillis should be "
255 "greater than 0");
256 }
257 }
258
259 // Then, if the pause time target parameter was not set, set it to
260 // the default value.
261 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
262 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
263 // The default pause time target in G1 is 200ms
264 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
265 } else {
266 // We do not allow the pause interval to be set without the
267 // pause time target
268 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
269 "without setting MaxGCPauseMillis");
270 }
271 }
272
273 // Then, if the interval parameter was not set, set it according to
274 // the pause time target (this will also deal with the case when the
275 // pause time target is the default value).
276 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
277 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
278 }
279
280 // Finally, make sure that the two parameters are consistent.
281 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
282 char buffer[256];
283 jio_snprintf(buffer, 256,
284 "MaxGCPauseMillis (%u) should be less than "
285 "GCPauseIntervalMillis (%u)",
286 MaxGCPauseMillis, GCPauseIntervalMillis);
287 vm_exit_during_initialization(buffer);
288 }
289
290 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
291 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
292 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
293
294 // start conservatively (around 50ms is about right)
295 _concurrent_mark_remark_times_ms->add(0.05);
296 _concurrent_mark_cleanup_times_ms->add(0.20);
297 _tenuring_threshold = MaxTenuringThreshold;
298 // _max_survivor_regions will be calculated by
299 // update_young_list_target_length() during initialization.
300 _max_survivor_regions = 0;
301
302 assert(GCTimeRatio > 0,
303 "we should have set it to a default value set_g1_gc_flags() "
304 "if a user set it to 0");
305 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
306
307 uintx reserve_perc = G1ReservePercent;
308 // Put an artificial ceiling on this so that it's not set to a silly value.
309 if (reserve_perc > 50) {
310 reserve_perc = 50;
311 warning("G1ReservePercent is set to a value that is too large, "
312 "it's been updated to %u", reserve_perc);
313 }
314 _reserve_factor = (double) reserve_perc / 100.0;
315 // This will be set when the heap is expanded
316 // for the first time during initialization.
317 _reserve_regions = 0;
318
319 _collectionSetChooser = new CollectionSetChooser();
320 }
321
322 void G1CollectorPolicy::initialize_alignments() {
323 _space_alignment = HeapRegion::GrainBytes;
324 size_t card_table_alignment = GenRemSet::max_alignment_constraint();
325 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
326 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
327 }
328
329 void G1CollectorPolicy::initialize_flags() {
330 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
331 FLAG_SET_ERGO(uintx, G1HeapRegionSize, HeapRegion::GrainBytes);
332 }
333
334 if (SurvivorRatio < 1) {
335 vm_exit_during_initialization("Invalid survivor ratio specified");
336 }
337 CollectorPolicy::initialize_flags();
338 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
339 }
340
341 void G1CollectorPolicy::post_heap_initialize() {
342 uintx max_regions = G1CollectedHeap::heap()->max_regions();
343 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
344 if (max_young_size != MaxNewSize) {
345 FLAG_SET_ERGO(uintx, MaxNewSize, max_young_size);
346 }
347 }
348
349 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
350 _min_desired_young_length(0), _max_desired_young_length(0) {
351 if (FLAG_IS_CMDLINE(NewRatio)) {
352 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
353 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
354 } else {
355 _sizer_kind = SizerNewRatio;
356 _adaptive_size = false;
357 return;
358 }
359 }
360
361 if (NewSize > MaxNewSize) {
362 if (FLAG_IS_CMDLINE(MaxNewSize)) {
363 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
364 "A new max generation size of " SIZE_FORMAT "k will be used.",
365 NewSize/K, MaxNewSize/K, NewSize/K);
366 }
367 MaxNewSize = NewSize;
368 }
369
370 if (FLAG_IS_CMDLINE(NewSize)) {
371 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
372 1U);
373 if (FLAG_IS_CMDLINE(MaxNewSize)) {
374 _max_desired_young_length =
375 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
376 1U);
377 _sizer_kind = SizerMaxAndNewSize;
378 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
379 } else {
380 _sizer_kind = SizerNewSizeOnly;
381 }
382 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
383 _max_desired_young_length =
384 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
385 1U);
386 _sizer_kind = SizerMaxNewSizeOnly;
387 }
388 }
389
390 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
391 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
392 return MAX2(1U, default_value);
393 }
394
395 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
396 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
397 return MAX2(1U, default_value);
398 }
399
400 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
401 assert(number_of_heap_regions > 0, "Heap must be initialized");
402
403 switch (_sizer_kind) {
404 case SizerDefaults:
405 *min_young_length = calculate_default_min_length(number_of_heap_regions);
406 *max_young_length = calculate_default_max_length(number_of_heap_regions);
407 break;
408 case SizerNewSizeOnly:
409 *max_young_length = calculate_default_max_length(number_of_heap_regions);
410 *max_young_length = MAX2(*min_young_length, *max_young_length);
411 break;
412 case SizerMaxNewSizeOnly:
413 *min_young_length = calculate_default_min_length(number_of_heap_regions);
414 *min_young_length = MIN2(*min_young_length, *max_young_length);
415 break;
416 case SizerMaxAndNewSize:
417 // Do nothing. Values set on the command line, don't update them at runtime.
418 break;
419 case SizerNewRatio:
420 *min_young_length = number_of_heap_regions / (NewRatio + 1);
421 *max_young_length = *min_young_length;
422 break;
423 default:
424 ShouldNotReachHere();
425 }
426
427 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
428 }
429
430 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
431 // We need to pass the desired values because recalculation may not update these
432 // values in some cases.
433 uint temp = _min_desired_young_length;
434 uint result = _max_desired_young_length;
435 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
436 return result;
437 }
438
439 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
440 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
441 &_max_desired_young_length);
442 }
443
444 void G1CollectorPolicy::init() {
445 // Set aside an initial future to_space.
446 _g1 = G1CollectedHeap::heap();
447
448 assert(Heap_lock->owned_by_self(), "Locking discipline.");
449
450 initialize_gc_policy_counters();
451
452 if (adaptive_young_list_length()) {
453 _young_list_fixed_length = 0;
454 } else {
455 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
456 }
457 _free_regions_at_end_of_collection = _g1->num_free_regions();
458 update_young_list_target_length();
459
460 // We may immediately start allocating regions and placing them on the
461 // collection set list. Initialize the per-collection set info
462 start_incremental_cset_building();
463 }
464
465 // Create the jstat counters for the policy.
466 void G1CollectorPolicy::initialize_gc_policy_counters() {
467 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
468 }
469
470 bool G1CollectorPolicy::predict_will_fit(uint young_length,
471 double base_time_ms,
472 uint base_free_regions,
473 double target_pause_time_ms) {
474 if (young_length >= base_free_regions) {
475 // end condition 1: not enough space for the young regions
476 return false;
477 }
478
479 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
480 size_t bytes_to_copy =
481 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
482 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
483 double young_other_time_ms = predict_young_other_time_ms(young_length);
484 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
485 if (pause_time_ms > target_pause_time_ms) {
486 // end condition 2: prediction is over the target pause time
487 return false;
488 }
489
490 size_t free_bytes =
491 (base_free_regions - young_length) * HeapRegion::GrainBytes;
492 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
493 // end condition 3: out-of-space (conservatively!)
494 return false;
495 }
496
497 // success!
498 return true;
499 }
500
501 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
502 // re-calculate the necessary reserve
503 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
504 // We use ceiling so that if reserve_regions_d is > 0.0 (but
505 // smaller than 1.0) we'll get 1.
506 _reserve_regions = (uint) ceil(reserve_regions_d);
507
508 _young_gen_sizer->heap_size_changed(new_number_of_regions);
509 }
510
511 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
512 uint base_min_length) {
513 uint desired_min_length = 0;
514 if (adaptive_young_list_length()) {
515 if (_alloc_rate_ms_seq->num() > 3) {
516 double now_sec = os::elapsedTime();
517 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
518 double alloc_rate_ms = predict_alloc_rate_ms();
519 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
520 } else {
521 // otherwise we don't have enough info to make the prediction
522 }
523 }
524 desired_min_length += base_min_length;
525 // make sure we don't go below any user-defined minimum bound
526 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
527 }
528
529 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
530 // Here, we might want to also take into account any additional
531 // constraints (i.e., user-defined minimum bound). Currently, we
532 // effectively don't set this bound.
533 return _young_gen_sizer->max_desired_young_length();
534 }
535
536 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
537 if (rs_lengths == (size_t) -1) {
538 // if it's set to the default value (-1), we should predict it;
539 // otherwise, use the given value.
540 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
541 }
542
543 // Calculate the absolute and desired min bounds.
544
545 // This is how many young regions we already have (currently: the survivors).
546 uint base_min_length = recorded_survivor_regions();
547 // This is the absolute minimum young length, which ensures that we
548 // can allocate one eden region in the worst-case.
549 uint absolute_min_length = base_min_length + 1;
550 uint desired_min_length =
551 calculate_young_list_desired_min_length(base_min_length);
552 if (desired_min_length < absolute_min_length) {
553 desired_min_length = absolute_min_length;
554 }
555
556 // Calculate the absolute and desired max bounds.
557
558 // We will try our best not to "eat" into the reserve.
559 uint absolute_max_length = 0;
560 if (_free_regions_at_end_of_collection > _reserve_regions) {
561 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
562 }
563 uint desired_max_length = calculate_young_list_desired_max_length();
564 if (desired_max_length > absolute_max_length) {
565 desired_max_length = absolute_max_length;
566 }
567
568 uint young_list_target_length = 0;
569 if (adaptive_young_list_length()) {
570 if (gcs_are_young()) {
571 young_list_target_length =
572 calculate_young_list_target_length(rs_lengths,
573 base_min_length,
574 desired_min_length,
575 desired_max_length);
576 _rs_lengths_prediction = rs_lengths;
577 } else {
578 // Don't calculate anything and let the code below bound it to
579 // the desired_min_length, i.e., do the next GC as soon as
580 // possible to maximize how many old regions we can add to it.
581 }
582 } else {
583 // The user asked for a fixed young gen so we'll fix the young gen
584 // whether the next GC is young or mixed.
585 young_list_target_length = _young_list_fixed_length;
586 }
587
588 // Make sure we don't go over the desired max length, nor under the
589 // desired min length. In case they clash, desired_min_length wins
590 // which is why that test is second.
591 if (young_list_target_length > desired_max_length) {
592 young_list_target_length = desired_max_length;
593 }
594 if (young_list_target_length < desired_min_length) {
595 young_list_target_length = desired_min_length;
596 }
597
598 assert(young_list_target_length > recorded_survivor_regions(),
599 "we should be able to allocate at least one eden region");
600 assert(young_list_target_length >= absolute_min_length, "post-condition");
601 _young_list_target_length = young_list_target_length;
602
603 update_max_gc_locker_expansion();
604 }
605
606 uint
607 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
608 uint base_min_length,
609 uint desired_min_length,
610 uint desired_max_length) {
611 assert(adaptive_young_list_length(), "pre-condition");
612 assert(gcs_are_young(), "only call this for young GCs");
613
614 // In case some edge-condition makes the desired max length too small...
615 if (desired_max_length <= desired_min_length) {
616 return desired_min_length;
617 }
618
619 // We'll adjust min_young_length and max_young_length not to include
620 // the already allocated young regions (i.e., so they reflect the
621 // min and max eden regions we'll allocate). The base_min_length
622 // will be reflected in the predictions by the
623 // survivor_regions_evac_time prediction.
624 assert(desired_min_length > base_min_length, "invariant");
625 uint min_young_length = desired_min_length - base_min_length;
626 assert(desired_max_length > base_min_length, "invariant");
627 uint max_young_length = desired_max_length - base_min_length;
628
629 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
630 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
631 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
632 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
633 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
634 double base_time_ms =
635 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
636 survivor_regions_evac_time;
637 uint available_free_regions = _free_regions_at_end_of_collection;
638 uint base_free_regions = 0;
639 if (available_free_regions > _reserve_regions) {
640 base_free_regions = available_free_regions - _reserve_regions;
641 }
642
643 // Here, we will make sure that the shortest young length that
644 // makes sense fits within the target pause time.
645
646 if (predict_will_fit(min_young_length, base_time_ms,
647 base_free_regions, target_pause_time_ms)) {
648 // The shortest young length will fit into the target pause time;
649 // we'll now check whether the absolute maximum number of young
650 // regions will fit in the target pause time. If not, we'll do
651 // a binary search between min_young_length and max_young_length.
652 if (predict_will_fit(max_young_length, base_time_ms,
653 base_free_regions, target_pause_time_ms)) {
654 // The maximum young length will fit into the target pause time.
655 // We are done so set min young length to the maximum length (as
656 // the result is assumed to be returned in min_young_length).
657 min_young_length = max_young_length;
658 } else {
659 // The maximum possible number of young regions will not fit within
660 // the target pause time so we'll search for the optimal
661 // length. The loop invariants are:
662 //
663 // min_young_length < max_young_length
664 // min_young_length is known to fit into the target pause time
665 // max_young_length is known not to fit into the target pause time
666 //
667 // Going into the loop we know the above hold as we've just
668 // checked them. Every time around the loop we check whether
669 // the middle value between min_young_length and
670 // max_young_length fits into the target pause time. If it
671 // does, it becomes the new min. If it doesn't, it becomes
672 // the new max. This way we maintain the loop invariants.
673
674 assert(min_young_length < max_young_length, "invariant");
675 uint diff = (max_young_length - min_young_length) / 2;
676 while (diff > 0) {
677 uint young_length = min_young_length + diff;
678 if (predict_will_fit(young_length, base_time_ms,
679 base_free_regions, target_pause_time_ms)) {
680 min_young_length = young_length;
681 } else {
682 max_young_length = young_length;
683 }
684 assert(min_young_length < max_young_length, "invariant");
685 diff = (max_young_length - min_young_length) / 2;
686 }
687 // The results is min_young_length which, according to the
688 // loop invariants, should fit within the target pause time.
689
690 // These are the post-conditions of the binary search above:
691 assert(min_young_length < max_young_length,
692 "otherwise we should have discovered that max_young_length "
693 "fits into the pause target and not done the binary search");
694 assert(predict_will_fit(min_young_length, base_time_ms,
695 base_free_regions, target_pause_time_ms),
696 "min_young_length, the result of the binary search, should "
697 "fit into the pause target");
698 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
699 base_free_regions, target_pause_time_ms),
700 "min_young_length, the result of the binary search, should be "
701 "optimal, so no larger length should fit into the pause target");
702 }
703 } else {
704 // Even the minimum length doesn't fit into the pause time
705 // target, return it as the result nevertheless.
706 }
707 return base_min_length + min_young_length;
708 }
709
710 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
711 double survivor_regions_evac_time = 0.0;
712 for (HeapRegion * r = _recorded_survivor_head;
713 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
714 r = r->get_next_young_region()) {
715 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
716 }
717 return survivor_regions_evac_time;
718 }
719
720 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
721 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
722
723 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
724 if (rs_lengths > _rs_lengths_prediction) {
725 // add 10% to avoid having to recalculate often
726 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
727 update_young_list_target_length(rs_lengths_prediction);
728 }
729 }
730
731
732
733 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
734 bool is_tlab,
735 bool* gc_overhead_limit_was_exceeded) {
736 guarantee(false, "Not using this policy feature yet.");
737 return NULL;
738 }
739
740 // This method controls how a collector handles one or more
741 // of its generations being fully allocated.
742 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
743 bool is_tlab) {
744 guarantee(false, "Not using this policy feature yet.");
745 return NULL;
746 }
747
748
749 #ifndef PRODUCT
750 bool G1CollectorPolicy::verify_young_ages() {
751 HeapRegion* head = _g1->young_list()->first_region();
752 return
753 verify_young_ages(head, _short_lived_surv_rate_group);
754 // also call verify_young_ages on any additional surv rate groups
755 }
756
757 bool
758 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
759 SurvRateGroup *surv_rate_group) {
760 guarantee( surv_rate_group != NULL, "pre-condition" );
761
762 const char* name = surv_rate_group->name();
763 bool ret = true;
764 int prev_age = -1;
765
766 for (HeapRegion* curr = head;
767 curr != NULL;
768 curr = curr->get_next_young_region()) {
769 SurvRateGroup* group = curr->surv_rate_group();
770 if (group == NULL && !curr->is_survivor()) {
771 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
772 ret = false;
773 }
774
775 if (surv_rate_group == group) {
776 int age = curr->age_in_surv_rate_group();
777
778 if (age < 0) {
779 gclog_or_tty->print_cr("## %s: encountered negative age", name);
780 ret = false;
781 }
782
783 if (age <= prev_age) {
784 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
785 "(%d, %d)", name, age, prev_age);
786 ret = false;
787 }
788 prev_age = age;
789 }
790 }
791
792 return ret;
793 }
794 #endif // PRODUCT
795
796 void G1CollectorPolicy::record_full_collection_start() {
797 _full_collection_start_sec = os::elapsedTime();
798 record_heap_size_info_at_start(true /* full */);
799 // Release the future to-space so that it is available for compaction into.
800 _g1->set_full_collection();
801 }
802
803 void G1CollectorPolicy::record_full_collection_end() {
804 // Consider this like a collection pause for the purposes of allocation
805 // since last pause.
806 double end_sec = os::elapsedTime();
807 double full_gc_time_sec = end_sec - _full_collection_start_sec;
808 double full_gc_time_ms = full_gc_time_sec * 1000.0;
809
810 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
811
812 update_recent_gc_times(end_sec, full_gc_time_ms);
813
814 _g1->clear_full_collection();
815
816 // "Nuke" the heuristics that control the young/mixed GC
817 // transitions and make sure we start with young GCs after the Full GC.
818 set_gcs_are_young(true);
819 _last_young_gc = false;
820 clear_initiate_conc_mark_if_possible();
821 clear_during_initial_mark_pause();
822 _in_marking_window = false;
823 _in_marking_window_im = false;
824
825 _short_lived_surv_rate_group->start_adding_regions();
826 // also call this on any additional surv rate groups
827
828 record_survivor_regions(0, NULL, NULL);
829
830 _free_regions_at_end_of_collection = _g1->num_free_regions();
831 // Reset survivors SurvRateGroup.
832 _survivor_surv_rate_group->reset();
833 update_young_list_target_length();
834 _collectionSetChooser->clear();
835 }
836
837 void G1CollectorPolicy::record_stop_world_start() {
838 _stop_world_start = os::elapsedTime();
839 }
840
841 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
842 // We only need to do this here as the policy will only be applied
843 // to the GC we're about to start. so, no point is calculating this
844 // every time we calculate / recalculate the target young length.
845 update_survivors_policy();
846
847 assert(_g1->used() == _g1->recalculate_used(),
848 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
849 _g1->used(), _g1->recalculate_used()));
850
851 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
852 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
853 _stop_world_start = 0.0;
854
855 record_heap_size_info_at_start(false /* full */);
856
857 phase_times()->record_cur_collection_start_sec(start_time_sec);
858 _pending_cards = _g1->pending_card_num();
859
860 _collection_set_bytes_used_before = 0;
861 _bytes_copied_during_gc = 0;
862
863 _last_gc_was_young = false;
864
865 // do that for any other surv rate groups
866 _short_lived_surv_rate_group->stop_adding_regions();
867 _survivors_age_table.clear();
868
869 assert( verify_young_ages(), "region age verification" );
870 }
871
872 void G1CollectorPolicy::record_concurrent_mark_init_end(double
873 mark_init_elapsed_time_ms) {
874 _during_marking = true;
875 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
876 clear_during_initial_mark_pause();
877 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
878 }
879
880 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
881 _mark_remark_start_sec = os::elapsedTime();
882 _during_marking = false;
883 }
884
885 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
886 double end_time_sec = os::elapsedTime();
887 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
888 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
889 _cur_mark_stop_world_time_ms += elapsed_time_ms;
890 _prev_collection_pause_end_ms += elapsed_time_ms;
891
892 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
893 }
894
895 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
896 _mark_cleanup_start_sec = os::elapsedTime();
897 }
898
899 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
900 _last_young_gc = true;
901 _in_marking_window = false;
902 }
903
904 void G1CollectorPolicy::record_concurrent_pause() {
905 if (_stop_world_start > 0.0) {
906 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
907 _trace_young_gen_time_data.record_yield_time(yield_ms);
908 }
909 }
910
911 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
912 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
913 return false;
914 }
915
916 size_t marking_initiating_used_threshold =
917 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
918 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
919 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
920
921 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
922 if (gcs_are_young() && !_last_young_gc) {
923 ergo_verbose5(ErgoConcCycles,
924 "request concurrent cycle initiation",
925 ergo_format_reason("occupancy higher than threshold")
926 ergo_format_byte("occupancy")
927 ergo_format_byte("allocation request")
928 ergo_format_byte_perc("threshold")
929 ergo_format_str("source"),
930 cur_used_bytes,
931 alloc_byte_size,
932 marking_initiating_used_threshold,
933 (double) InitiatingHeapOccupancyPercent,
934 source);
935 return true;
936 } else {
937 ergo_verbose5(ErgoConcCycles,
938 "do not request concurrent cycle initiation",
939 ergo_format_reason("still doing mixed collections")
940 ergo_format_byte("occupancy")
941 ergo_format_byte("allocation request")
942 ergo_format_byte_perc("threshold")
943 ergo_format_str("source"),
944 cur_used_bytes,
945 alloc_byte_size,
946 marking_initiating_used_threshold,
947 (double) InitiatingHeapOccupancyPercent,
948 source);
949 }
950 }
951
952 return false;
953 }
954
955 // Anything below that is considered to be zero
956 #define MIN_TIMER_GRANULARITY 0.0000001
957
958 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
959 double end_time_sec = os::elapsedTime();
960 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
961 "otherwise, the subtraction below does not make sense");
962 size_t rs_size =
963 _cur_collection_pause_used_regions_at_start - cset_region_length();
964 size_t cur_used_bytes = _g1->used();
965 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
966 bool last_pause_included_initial_mark = false;
967 bool update_stats = !_g1->evacuation_failed();
968
969 #ifndef PRODUCT
970 if (G1YoungSurvRateVerbose) {
971 gclog_or_tty->cr();
972 _short_lived_surv_rate_group->print();
973 // do that for any other surv rate groups too
974 }
975 #endif // PRODUCT
976
977 last_pause_included_initial_mark = during_initial_mark_pause();
978 if (last_pause_included_initial_mark) {
979 record_concurrent_mark_init_end(0.0);
980 } else if (need_to_start_conc_mark("end of GC")) {
981 // Note: this might have already been set, if during the last
982 // pause we decided to start a cycle but at the beginning of
983 // this pause we decided to postpone it. That's OK.
984 set_initiate_conc_mark_if_possible();
985 }
986
987 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
988 end_time_sec, false);
989
990 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
991 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
992
993 if (update_stats) {
994 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
995 // this is where we update the allocation rate of the application
996 double app_time_ms =
997 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
998 if (app_time_ms < MIN_TIMER_GRANULARITY) {
999 // This usually happens due to the timer not having the required
1000 // granularity. Some Linuxes are the usual culprits.
1001 // We'll just set it to something (arbitrarily) small.
1002 app_time_ms = 1.0;
1003 }
1004 // We maintain the invariant that all objects allocated by mutator
1005 // threads will be allocated out of eden regions. So, we can use
1006 // the eden region number allocated since the previous GC to
1007 // calculate the application's allocate rate. The only exception
1008 // to that is humongous objects that are allocated separately. But
1009 // given that humongous object allocations do not really affect
1010 // either the pause's duration nor when the next pause will take
1011 // place we can safely ignore them here.
1012 uint regions_allocated = eden_cset_region_length();
1013 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1014 _alloc_rate_ms_seq->add(alloc_rate_ms);
1015
1016 double interval_ms =
1017 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1018 update_recent_gc_times(end_time_sec, pause_time_ms);
1019 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1020 if (recent_avg_pause_time_ratio() < 0.0 ||
1021 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1022 #ifndef PRODUCT
1023 // Dump info to allow post-facto debugging
1024 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1025 gclog_or_tty->print_cr("-------------------------------------------");
1026 gclog_or_tty->print_cr("Recent GC Times (ms):");
1027 _recent_gc_times_ms->dump();
1028 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1029 _recent_prev_end_times_for_all_gcs_sec->dump();
1030 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1031 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1032 // In debug mode, terminate the JVM if the user wants to debug at this point.
1033 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1034 #endif // !PRODUCT
1035 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1036 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1037 if (_recent_avg_pause_time_ratio < 0.0) {
1038 _recent_avg_pause_time_ratio = 0.0;
1039 } else {
1040 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1041 _recent_avg_pause_time_ratio = 1.0;
1042 }
1043 }
1044 }
1045
1046 bool new_in_marking_window = _in_marking_window;
1047 bool new_in_marking_window_im = false;
1048 if (last_pause_included_initial_mark) {
1049 new_in_marking_window = true;
1050 new_in_marking_window_im = true;
1051 }
1052
1053 if (_last_young_gc) {
1054 // This is supposed to to be the "last young GC" before we start
1055 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1056
1057 if (!last_pause_included_initial_mark) {
1058 if (next_gc_should_be_mixed("start mixed GCs",
1059 "do not start mixed GCs")) {
1060 set_gcs_are_young(false);
1061 }
1062 } else {
1063 ergo_verbose0(ErgoMixedGCs,
1064 "do not start mixed GCs",
1065 ergo_format_reason("concurrent cycle is about to start"));
1066 }
1067 _last_young_gc = false;
1068 }
1069
1070 if (!_last_gc_was_young) {
1071 // This is a mixed GC. Here we decide whether to continue doing
1072 // mixed GCs or not.
1073
1074 if (!next_gc_should_be_mixed("continue mixed GCs",
1075 "do not continue mixed GCs")) {
1076 set_gcs_are_young(true);
1077 }
1078 }
1079
1080 _short_lived_surv_rate_group->start_adding_regions();
1081 // Do that for any other surv rate groups
1082
1083 if (update_stats) {
1084 double cost_per_card_ms = 0.0;
1085 if (_pending_cards > 0) {
1086 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1087 _cost_per_card_ms_seq->add(cost_per_card_ms);
1088 }
1089
1090 size_t cards_scanned = _g1->cards_scanned();
1091
1092 double cost_per_entry_ms = 0.0;
1093 if (cards_scanned > 10) {
1094 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1095 if (_last_gc_was_young) {
1096 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1097 } else {
1098 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1099 }
1100 }
1101
1102 if (_max_rs_lengths > 0) {
1103 double cards_per_entry_ratio =
1104 (double) cards_scanned / (double) _max_rs_lengths;
1105 if (_last_gc_was_young) {
1106 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1107 } else {
1108 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1109 }
1110 }
1111
1112 // This is defensive. For a while _max_rs_lengths could get
1113 // smaller than _recorded_rs_lengths which was causing
1114 // rs_length_diff to get very large and mess up the RSet length
1115 // predictions. The reason was unsafe concurrent updates to the
1116 // _inc_cset_recorded_rs_lengths field which the code below guards
1117 // against (see CR 7118202). This bug has now been fixed (see CR
1118 // 7119027). However, I'm still worried that
1119 // _inc_cset_recorded_rs_lengths might still end up somewhat
1120 // inaccurate. The concurrent refinement thread calculates an
1121 // RSet's length concurrently with other CR threads updating it
1122 // which might cause it to calculate the length incorrectly (if,
1123 // say, it's in mid-coarsening). So I'll leave in the defensive
1124 // conditional below just in case.
1125 size_t rs_length_diff = 0;
1126 if (_max_rs_lengths > _recorded_rs_lengths) {
1127 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1128 }
1129 _rs_length_diff_seq->add((double) rs_length_diff);
1130
1131 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1132 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1133 double cost_per_byte_ms = 0.0;
1134
1135 if (copied_bytes > 0) {
1136 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1137 if (_in_marking_window) {
1138 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1139 } else {
1140 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1141 }
1142 }
1143
1144 double all_other_time_ms = pause_time_ms -
1145 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1146 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1147
1148 double young_other_time_ms = 0.0;
1149 if (young_cset_region_length() > 0) {
1150 young_other_time_ms =
1151 phase_times()->young_cset_choice_time_ms() +
1152 phase_times()->young_free_cset_time_ms();
1153 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1154 (double) young_cset_region_length());
1155 }
1156 double non_young_other_time_ms = 0.0;
1157 if (old_cset_region_length() > 0) {
1158 non_young_other_time_ms =
1159 phase_times()->non_young_cset_choice_time_ms() +
1160 phase_times()->non_young_free_cset_time_ms();
1161
1162 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1163 (double) old_cset_region_length());
1164 }
1165
1166 double constant_other_time_ms = all_other_time_ms -
1167 (young_other_time_ms + non_young_other_time_ms);
1168 _constant_other_time_ms_seq->add(constant_other_time_ms);
1169
1170 double survival_ratio = 0.0;
1171 if (_collection_set_bytes_used_before > 0) {
1172 survival_ratio = (double) _bytes_copied_during_gc /
1173 (double) _collection_set_bytes_used_before;
1174 }
1175
1176 _pending_cards_seq->add((double) _pending_cards);
1177 _rs_lengths_seq->add((double) _max_rs_lengths);
1178 }
1179
1180 _in_marking_window = new_in_marking_window;
1181 _in_marking_window_im = new_in_marking_window_im;
1182 _free_regions_at_end_of_collection = _g1->num_free_regions();
1183 update_young_list_target_length();
1184
1185 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1186 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1187 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1188 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1189
1190 _collectionSetChooser->verify();
1191 }
1192
1193 #define EXT_SIZE_FORMAT "%.1f%s"
1194 #define EXT_SIZE_PARAMS(bytes) \
1195 byte_size_in_proper_unit((double)(bytes)), \
1196 proper_unit_for_byte_size((bytes))
1197
1198 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1199 YoungList* young_list = _g1->young_list();
1200 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1201 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1202 _heap_capacity_bytes_before_gc = _g1->capacity();
1203 _heap_used_bytes_before_gc = _g1->used();
1204 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1205
1206 _eden_capacity_bytes_before_gc =
1207 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1208
1209 if (full) {
1210 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1211 }
1212 }
1213
1214 void G1CollectorPolicy::print_heap_transition() {
1215 _g1->print_size_transition(gclog_or_tty,
1216 _heap_used_bytes_before_gc,
1217 _g1->used(),
1218 _g1->capacity());
1219 }
1220
1221 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {
1222 YoungList* young_list = _g1->young_list();
1223
1224 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1225 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1226 size_t heap_used_bytes_after_gc = _g1->used();
1227
1228 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1229 size_t eden_capacity_bytes_after_gc =
1230 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1231
1232 gclog_or_tty->print(
1233 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1234 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1235 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1236 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1237 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1238 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1239 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1240 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1241 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1242 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1243 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1244 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1245 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1246 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1247
1248 if (full) {
1249 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1250 }
1251
1252 gclog_or_tty->cr();
1253 }
1254
1255 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1256 double update_rs_processed_buffers,
1257 double goal_ms) {
1258 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1259 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1260
1261 if (G1UseAdaptiveConcRefinement) {
1262 const int k_gy = 3, k_gr = 6;
1263 const double inc_k = 1.1, dec_k = 0.9;
1264
1265 int g = cg1r->green_zone();
1266 if (update_rs_time > goal_ms) {
1267 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1268 } else {
1269 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1270 g = (int)MAX2(g * inc_k, g + 1.0);
1271 }
1272 }
1273 // Change the refinement threads params
1274 cg1r->set_green_zone(g);
1275 cg1r->set_yellow_zone(g * k_gy);
1276 cg1r->set_red_zone(g * k_gr);
1277 cg1r->reinitialize_threads();
1278
1279 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1280 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1281 cg1r->yellow_zone());
1282 // Change the barrier params
1283 dcqs.set_process_completed_threshold(processing_threshold);
1284 dcqs.set_max_completed_queue(cg1r->red_zone());
1285 }
1286
1287 int curr_queue_size = dcqs.completed_buffers_num();
1288 if (curr_queue_size >= cg1r->yellow_zone()) {
1289 dcqs.set_completed_queue_padding(curr_queue_size);
1290 } else {
1291 dcqs.set_completed_queue_padding(0);
1292 }
1293 dcqs.notify_if_necessary();
1294 }
1295
1296 double
1297 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1298 size_t scanned_cards) {
1299 return
1300 predict_rs_update_time_ms(pending_cards) +
1301 predict_rs_scan_time_ms(scanned_cards) +
1302 predict_constant_other_time_ms();
1303 }
1304
1305 double
1306 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1307 size_t rs_length = predict_rs_length_diff();
1308 size_t card_num;
1309 if (gcs_are_young()) {
1310 card_num = predict_young_card_num(rs_length);
1311 } else {
1312 card_num = predict_non_young_card_num(rs_length);
1313 }
1314 return predict_base_elapsed_time_ms(pending_cards, card_num);
1315 }
1316
1317 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1318 size_t bytes_to_copy;
1319 if (hr->is_marked())
1320 bytes_to_copy = hr->max_live_bytes();
1321 else {
1322 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1323 int age = hr->age_in_surv_rate_group();
1324 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1325 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1326 }
1327 return bytes_to_copy;
1328 }
1329
1330 double
1331 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1332 bool for_young_gc) {
1333 size_t rs_length = hr->rem_set()->occupied();
1334 size_t card_num;
1335
1336 // Predicting the number of cards is based on which type of GC
1337 // we're predicting for.
1338 if (for_young_gc) {
1339 card_num = predict_young_card_num(rs_length);
1340 } else {
1341 card_num = predict_non_young_card_num(rs_length);
1342 }
1343 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1344
1345 double region_elapsed_time_ms =
1346 predict_rs_scan_time_ms(card_num) +
1347 predict_object_copy_time_ms(bytes_to_copy);
1348
1349 // The prediction of the "other" time for this region is based
1350 // upon the region type and NOT the GC type.
1351 if (hr->is_young()) {
1352 region_elapsed_time_ms += predict_young_other_time_ms(1);
1353 } else {
1354 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1355 }
1356 return region_elapsed_time_ms;
1357 }
1358
1359 void
1360 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1361 uint survivor_cset_region_length) {
1362 _eden_cset_region_length = eden_cset_region_length;
1363 _survivor_cset_region_length = survivor_cset_region_length;
1364 _old_cset_region_length = 0;
1365 }
1366
1367 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1368 _recorded_rs_lengths = rs_lengths;
1369 }
1370
1371 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1372 double elapsed_ms) {
1373 _recent_gc_times_ms->add(elapsed_ms);
1374 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1375 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1376 }
1377
1378 size_t G1CollectorPolicy::expansion_amount() {
1379 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1380 double threshold = _gc_overhead_perc;
1381 if (recent_gc_overhead > threshold) {
1382 // We will double the existing space, or take
1383 // G1ExpandByPercentOfAvailable % of the available expansion
1384 // space, whichever is smaller, bounded below by a minimum
1385 // expansion (unless that's all that's left.)
1386 const size_t min_expand_bytes = 1*M;
1387 size_t reserved_bytes = _g1->max_capacity();
1388 size_t committed_bytes = _g1->capacity();
1389 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1390 size_t expand_bytes;
1391 size_t expand_bytes_via_pct =
1392 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1393 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1394 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1395 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1396
1397 ergo_verbose5(ErgoHeapSizing,
1398 "attempt heap expansion",
1399 ergo_format_reason("recent GC overhead higher than "
1400 "threshold after GC")
1401 ergo_format_perc("recent GC overhead")
1402 ergo_format_perc("threshold")
1403 ergo_format_byte("uncommitted")
1404 ergo_format_byte_perc("calculated expansion amount"),
1405 recent_gc_overhead, threshold,
1406 uncommitted_bytes,
1407 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1408
1409 return expand_bytes;
1410 } else {
1411 return 0;
1412 }
1413 }
1414
1415 void G1CollectorPolicy::print_tracing_info() const {
1416 _trace_young_gen_time_data.print();
1417 _trace_old_gen_time_data.print();
1418 }
1419
1420 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1421 #ifndef PRODUCT
1422 _short_lived_surv_rate_group->print_surv_rate_summary();
1423 // add this call for any other surv rate groups
1424 #endif // PRODUCT
1425 }
1426
1427 bool G1CollectorPolicy::is_young_list_full() {
1428 uint young_list_length = _g1->young_list()->length();
1429 uint young_list_target_length = _young_list_target_length;
1430 return young_list_length >= young_list_target_length;
1431 }
1432
1433 bool G1CollectorPolicy::can_expand_young_list() {
1434 uint young_list_length = _g1->young_list()->length();
1435 uint young_list_max_length = _young_list_max_length;
1436 return young_list_length < young_list_max_length;
1437 }
1438
1439 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1440 uint expansion_region_num = 0;
1441 if (GCLockerEdenExpansionPercent > 0) {
1442 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1443 double expansion_region_num_d = perc * (double) _young_list_target_length;
1444 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1445 // less than 1.0) we'll get 1.
1446 expansion_region_num = (uint) ceil(expansion_region_num_d);
1447 } else {
1448 assert(expansion_region_num == 0, "sanity");
1449 }
1450 _young_list_max_length = _young_list_target_length + expansion_region_num;
1451 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1452 }
1453
1454 // Calculates survivor space parameters.
1455 void G1CollectorPolicy::update_survivors_policy() {
1456 double max_survivor_regions_d =
1457 (double) _young_list_target_length / (double) SurvivorRatio;
1458 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1459 // smaller than 1.0) we'll get 1.
1460 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1461
1462 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1463 HeapRegion::GrainWords * _max_survivor_regions);
1464 }
1465
1466 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1467 GCCause::Cause gc_cause) {
1468 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1469 if (!during_cycle) {
1470 ergo_verbose1(ErgoConcCycles,
1471 "request concurrent cycle initiation",
1472 ergo_format_reason("requested by GC cause")
1473 ergo_format_str("GC cause"),
1474 GCCause::to_string(gc_cause));
1475 set_initiate_conc_mark_if_possible();
1476 return true;
1477 } else {
1478 ergo_verbose1(ErgoConcCycles,
1479 "do not request concurrent cycle initiation",
1480 ergo_format_reason("concurrent cycle already in progress")
1481 ergo_format_str("GC cause"),
1482 GCCause::to_string(gc_cause));
1483 return false;
1484 }
1485 }
1486
1487 void
1488 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1489 // We are about to decide on whether this pause will be an
1490 // initial-mark pause.
1491
1492 // First, during_initial_mark_pause() should not be already set. We
1493 // will set it here if we have to. However, it should be cleared by
1494 // the end of the pause (it's only set for the duration of an
1495 // initial-mark pause).
1496 assert(!during_initial_mark_pause(), "pre-condition");
1497
1498 if (initiate_conc_mark_if_possible()) {
1499 // We had noticed on a previous pause that the heap occupancy has
1500 // gone over the initiating threshold and we should start a
1501 // concurrent marking cycle. So we might initiate one.
1502
1503 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1504 if (!during_cycle) {
1505 // The concurrent marking thread is not "during a cycle", i.e.,
1506 // it has completed the last one. So we can go ahead and
1507 // initiate a new cycle.
1508
1509 set_during_initial_mark_pause();
1510 // We do not allow mixed GCs during marking.
1511 if (!gcs_are_young()) {
1512 set_gcs_are_young(true);
1513 ergo_verbose0(ErgoMixedGCs,
1514 "end mixed GCs",
1515 ergo_format_reason("concurrent cycle is about to start"));
1516 }
1517
1518 // And we can now clear initiate_conc_mark_if_possible() as
1519 // we've already acted on it.
1520 clear_initiate_conc_mark_if_possible();
1521
1522 ergo_verbose0(ErgoConcCycles,
1523 "initiate concurrent cycle",
1524 ergo_format_reason("concurrent cycle initiation requested"));
1525 } else {
1526 // The concurrent marking thread is still finishing up the
1527 // previous cycle. If we start one right now the two cycles
1528 // overlap. In particular, the concurrent marking thread might
1529 // be in the process of clearing the next marking bitmap (which
1530 // we will use for the next cycle if we start one). Starting a
1531 // cycle now will be bad given that parts of the marking
1532 // information might get cleared by the marking thread. And we
1533 // cannot wait for the marking thread to finish the cycle as it
1534 // periodically yields while clearing the next marking bitmap
1535 // and, if it's in a yield point, it's waiting for us to
1536 // finish. So, at this point we will not start a cycle and we'll
1537 // let the concurrent marking thread complete the last one.
1538 ergo_verbose0(ErgoConcCycles,
1539 "do not initiate concurrent cycle",
1540 ergo_format_reason("concurrent cycle already in progress"));
1541 }
1542 }
1543 }
1544
1545 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1546 G1CollectedHeap* _g1h;
1547 CSetChooserParUpdater _cset_updater;
1548
1549 public:
1550 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1551 uint chunk_size) :
1552 _g1h(G1CollectedHeap::heap()),
1553 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1554
1555 bool doHeapRegion(HeapRegion* r) {
1556 // Do we have any marking information for this region?
1557 if (r->is_marked()) {
1558 // We will skip any region that's currently used as an old GC
1559 // alloc region (we should not consider those for collection
1560 // before we fill them up).
1561 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1562 _cset_updater.add_region(r);
1563 }
1564 }
1565 return false;
1566 }
1567 };
1568
1569 class ParKnownGarbageTask: public AbstractGangTask {
1570 CollectionSetChooser* _hrSorted;
1571 uint _chunk_size;
1572 G1CollectedHeap* _g1;
1573 HeapRegionClaimer _hrclaimer;
1574
1575 public:
1576 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1577 AbstractGangTask("ParKnownGarbageTask"),
1578 _hrSorted(hrSorted), _chunk_size(chunk_size),
1579 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1580
1581 void work(uint worker_id) {
1582 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1583 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1584 }
1585 };
1586
1587 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) {
1588 assert(n_workers > 0, "Active gc workers should be greater than 0");
1589 const uint overpartition_factor = 4;
1590 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1591 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1592 }
1593
1594 void
1595 G1CollectorPolicy::record_concurrent_mark_cleanup_end(uint n_workers) {
1596 _collectionSetChooser->clear();
1597
1598 uint n_regions = _g1->num_regions();
1599 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1600 _collectionSetChooser->prepare_for_par_region_addition(n_regions, chunk_size);
1601 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1602 _g1->workers()->run_task(&par_known_garbage_task);
1603
1604 _collectionSetChooser->sort_regions();
1605
1606 double end_sec = os::elapsedTime();
1607 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1608 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1609 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1610 _prev_collection_pause_end_ms += elapsed_time_ms;
1611 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1612 }
1613
1614 // Add the heap region at the head of the non-incremental collection set
1615 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1616 assert(_inc_cset_build_state == Active, "Precondition");
1617 assert(hr->is_old(), "the region should be old");
1618
1619 assert(!hr->in_collection_set(), "should not already be in the CSet");
1620 hr->set_in_collection_set(true);
1621 hr->set_next_in_collection_set(_collection_set);
1622 _collection_set = hr;
1623 _collection_set_bytes_used_before += hr->used();
1624 _g1->register_old_region_with_in_cset_fast_test(hr);
1625 size_t rs_length = hr->rem_set()->occupied();
1626 _recorded_rs_lengths += rs_length;
1627 _old_cset_region_length += 1;
1628 }
1629
1630 // Initialize the per-collection-set information
1631 void G1CollectorPolicy::start_incremental_cset_building() {
1632 assert(_inc_cset_build_state == Inactive, "Precondition");
1633
1634 _inc_cset_head = NULL;
1635 _inc_cset_tail = NULL;
1636 _inc_cset_bytes_used_before = 0;
1637
1638 _inc_cset_max_finger = 0;
1639 _inc_cset_recorded_rs_lengths = 0;
1640 _inc_cset_recorded_rs_lengths_diffs = 0;
1641 _inc_cset_predicted_elapsed_time_ms = 0.0;
1642 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1643 _inc_cset_build_state = Active;
1644 }
1645
1646 void G1CollectorPolicy::finalize_incremental_cset_building() {
1647 assert(_inc_cset_build_state == Active, "Precondition");
1648 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1649
1650 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1651 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1652 // that adds a new region to the CSet. Further updates by the
1653 // concurrent refinement thread that samples the young RSet lengths
1654 // are accumulated in the *_diffs fields. Here we add the diffs to
1655 // the "main" fields.
1656
1657 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1658 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1659 } else {
1660 // This is defensive. The diff should in theory be always positive
1661 // as RSets can only grow between GCs. However, given that we
1662 // sample their size concurrently with other threads updating them
1663 // it's possible that we might get the wrong size back, which
1664 // could make the calculations somewhat inaccurate.
1665 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1666 if (_inc_cset_recorded_rs_lengths >= diffs) {
1667 _inc_cset_recorded_rs_lengths -= diffs;
1668 } else {
1669 _inc_cset_recorded_rs_lengths = 0;
1670 }
1671 }
1672 _inc_cset_predicted_elapsed_time_ms +=
1673 _inc_cset_predicted_elapsed_time_ms_diffs;
1674
1675 _inc_cset_recorded_rs_lengths_diffs = 0;
1676 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1677 }
1678
1679 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1680 // This routine is used when:
1681 // * adding survivor regions to the incremental cset at the end of an
1682 // evacuation pause,
1683 // * adding the current allocation region to the incremental cset
1684 // when it is retired, and
1685 // * updating existing policy information for a region in the
1686 // incremental cset via young list RSet sampling.
1687 // Therefore this routine may be called at a safepoint by the
1688 // VM thread, or in-between safepoints by mutator threads (when
1689 // retiring the current allocation region) or a concurrent
1690 // refine thread (RSet sampling).
1691
1692 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1693 size_t used_bytes = hr->used();
1694 _inc_cset_recorded_rs_lengths += rs_length;
1695 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1696 _inc_cset_bytes_used_before += used_bytes;
1697
1698 // Cache the values we have added to the aggregated information
1699 // in the heap region in case we have to remove this region from
1700 // the incremental collection set, or it is updated by the
1701 // rset sampling code
1702 hr->set_recorded_rs_length(rs_length);
1703 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1704 }
1705
1706 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1707 size_t new_rs_length) {
1708 // Update the CSet information that is dependent on the new RS length
1709 assert(hr->is_young(), "Precondition");
1710 assert(!SafepointSynchronize::is_at_safepoint(),
1711 "should not be at a safepoint");
1712
1713 // We could have updated _inc_cset_recorded_rs_lengths and
1714 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1715 // that atomically, as this code is executed by a concurrent
1716 // refinement thread, potentially concurrently with a mutator thread
1717 // allocating a new region and also updating the same fields. To
1718 // avoid the atomic operations we accumulate these updates on two
1719 // separate fields (*_diffs) and we'll just add them to the "main"
1720 // fields at the start of a GC.
1721
1722 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1723 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1724 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1725
1726 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1727 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1728 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1729 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1730
1731 hr->set_recorded_rs_length(new_rs_length);
1732 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1733 }
1734
1735 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1736 assert(hr->is_young(), "invariant");
1737 assert(hr->young_index_in_cset() > -1, "should have already been set");
1738 assert(_inc_cset_build_state == Active, "Precondition");
1739
1740 // We need to clear and set the cached recorded/cached collection set
1741 // information in the heap region here (before the region gets added
1742 // to the collection set). An individual heap region's cached values
1743 // are calculated, aggregated with the policy collection set info,
1744 // and cached in the heap region here (initially) and (subsequently)
1745 // by the Young List sampling code.
1746
1747 size_t rs_length = hr->rem_set()->occupied();
1748 add_to_incremental_cset_info(hr, rs_length);
1749
1750 HeapWord* hr_end = hr->end();
1751 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1752
1753 assert(!hr->in_collection_set(), "invariant");
1754 hr->set_in_collection_set(true);
1755 assert( hr->next_in_collection_set() == NULL, "invariant");
1756
1757 _g1->register_young_region_with_in_cset_fast_test(hr);
1758 }
1759
1760 // Add the region at the RHS of the incremental cset
1761 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1762 // We should only ever be appending survivors at the end of a pause
1763 assert(hr->is_survivor(), "Logic");
1764
1765 // Do the 'common' stuff
1766 add_region_to_incremental_cset_common(hr);
1767
1768 // Now add the region at the right hand side
1769 if (_inc_cset_tail == NULL) {
1770 assert(_inc_cset_head == NULL, "invariant");
1771 _inc_cset_head = hr;
1772 } else {
1773 _inc_cset_tail->set_next_in_collection_set(hr);
1774 }
1775 _inc_cset_tail = hr;
1776 }
1777
1778 // Add the region to the LHS of the incremental cset
1779 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1780 // Survivors should be added to the RHS at the end of a pause
1781 assert(hr->is_eden(), "Logic");
1782
1783 // Do the 'common' stuff
1784 add_region_to_incremental_cset_common(hr);
1785
1786 // Add the region at the left hand side
1787 hr->set_next_in_collection_set(_inc_cset_head);
1788 if (_inc_cset_head == NULL) {
1789 assert(_inc_cset_tail == NULL, "Invariant");
1790 _inc_cset_tail = hr;
1791 }
1792 _inc_cset_head = hr;
1793 }
1794
1795 #ifndef PRODUCT
1796 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1797 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1798
1799 st->print_cr("\nCollection_set:");
1800 HeapRegion* csr = list_head;
1801 while (csr != NULL) {
1802 HeapRegion* next = csr->next_in_collection_set();
1803 assert(csr->in_collection_set(), "bad CS");
1804 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1805 HR_FORMAT_PARAMS(csr),
1806 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1807 csr->age_in_surv_rate_group_cond());
1808 csr = next;
1809 }
1810 }
1811 #endif // !PRODUCT
1812
1813 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1814 // Returns the given amount of reclaimable bytes (that represents
1815 // the amount of reclaimable space still to be collected) as a
1816 // percentage of the current heap capacity.
1817 size_t capacity_bytes = _g1->capacity();
1818 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1819 }
1820
1821 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1822 const char* false_action_str) {
1823 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1824 if (cset_chooser->is_empty()) {
1825 ergo_verbose0(ErgoMixedGCs,
1826 false_action_str,
1827 ergo_format_reason("candidate old regions not available"));
1828 return false;
1829 }
1830
1831 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1832 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1833 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1834 double threshold = (double) G1HeapWastePercent;
1835 if (reclaimable_perc <= threshold) {
1836 ergo_verbose4(ErgoMixedGCs,
1837 false_action_str,
1838 ergo_format_reason("reclaimable percentage not over threshold")
1839 ergo_format_region("candidate old regions")
1840 ergo_format_byte_perc("reclaimable")
1841 ergo_format_perc("threshold"),
1842 cset_chooser->remaining_regions(),
1843 reclaimable_bytes,
1844 reclaimable_perc, threshold);
1845 return false;
1846 }
1847
1848 ergo_verbose4(ErgoMixedGCs,
1849 true_action_str,
1850 ergo_format_reason("candidate old regions available")
1851 ergo_format_region("candidate old regions")
1852 ergo_format_byte_perc("reclaimable")
1853 ergo_format_perc("threshold"),
1854 cset_chooser->remaining_regions(),
1855 reclaimable_bytes,
1856 reclaimable_perc, threshold);
1857 return true;
1858 }
1859
1860 uint G1CollectorPolicy::calc_min_old_cset_length() {
1861 // The min old CSet region bound is based on the maximum desired
1862 // number of mixed GCs after a cycle. I.e., even if some old regions
1863 // look expensive, we should add them to the CSet anyway to make
1864 // sure we go through the available old regions in no more than the
1865 // maximum desired number of mixed GCs.
1866 //
1867 // The calculation is based on the number of marked regions we added
1868 // to the CSet chooser in the first place, not how many remain, so
1869 // that the result is the same during all mixed GCs that follow a cycle.
1870
1871 const size_t region_num = (size_t) _collectionSetChooser->length();
1872 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1873 size_t result = region_num / gc_num;
1874 // emulate ceiling
1875 if (result * gc_num < region_num) {
1876 result += 1;
1877 }
1878 return (uint) result;
1879 }
1880
1881 uint G1CollectorPolicy::calc_max_old_cset_length() {
1882 // The max old CSet region bound is based on the threshold expressed
1883 // as a percentage of the heap size. I.e., it should bound the
1884 // number of old regions added to the CSet irrespective of how many
1885 // of them are available.
1886
1887 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1888 const size_t region_num = g1h->num_regions();
1889 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1890 size_t result = region_num * perc / 100;
1891 // emulate ceiling
1892 if (100 * result < region_num * perc) {
1893 result += 1;
1894 }
1895 return (uint) result;
1896 }
1897
1898
1899 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1900 double young_start_time_sec = os::elapsedTime();
1901
1902 YoungList* young_list = _g1->young_list();
1903 finalize_incremental_cset_building();
1904
1905 guarantee(target_pause_time_ms > 0.0,
1906 err_msg("target_pause_time_ms = %1.6lf should be positive",
1907 target_pause_time_ms));
1908 guarantee(_collection_set == NULL, "Precondition");
1909
1910 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1911 double predicted_pause_time_ms = base_time_ms;
1912 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1913
1914 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1915 "start choosing CSet",
1916 ergo_format_size("_pending_cards")
1917 ergo_format_ms("predicted base time")
1918 ergo_format_ms("remaining time")
1919 ergo_format_ms("target pause time"),
1920 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1921
1922 _last_gc_was_young = gcs_are_young() ? true : false;
1923
1924 if (_last_gc_was_young) {
1925 _trace_young_gen_time_data.increment_young_collection_count();
1926 } else {
1927 _trace_young_gen_time_data.increment_mixed_collection_count();
1928 }
1929
1930 // The young list is laid with the survivor regions from the previous
1931 // pause are appended to the RHS of the young list, i.e.
1932 // [Newly Young Regions ++ Survivors from last pause].
1933
1934 uint survivor_region_length = young_list->survivor_length();
1935 uint eden_region_length = young_list->length() - survivor_region_length;
1936 init_cset_region_lengths(eden_region_length, survivor_region_length);
1937
1938 HeapRegion* hr = young_list->first_survivor_region();
1939 while (hr != NULL) {
1940 assert(hr->is_survivor(), "badly formed young list");
1941 // There is a convention that all the young regions in the CSet
1942 // are tagged as "eden", so we do this for the survivors here. We
1943 // use the special set_eden_pre_gc() as it doesn't check that the
1944 // region is free (which is not the case here).
1945 hr->set_eden_pre_gc();
1946 hr = hr->get_next_young_region();
1947 }
1948
1949 // Clear the fields that point to the survivor list - they are all young now.
1950 young_list->clear_survivors();
1951
1952 _collection_set = _inc_cset_head;
1953 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1954 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1955 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1956
1957 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1958 "add young regions to CSet",
1959 ergo_format_region("eden")
1960 ergo_format_region("survivors")
1961 ergo_format_ms("predicted young region time"),
1962 eden_region_length, survivor_region_length,
1963 _inc_cset_predicted_elapsed_time_ms);
1964
1965 // The number of recorded young regions is the incremental
1966 // collection set's current size
1967 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1968
1969 double young_end_time_sec = os::elapsedTime();
1970 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1971
1972 // Set the start of the non-young choice time.
1973 double non_young_start_time_sec = young_end_time_sec;
1974
1975 if (!gcs_are_young()) {
1976 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1977 cset_chooser->verify();
1978 const uint min_old_cset_length = calc_min_old_cset_length();
1979 const uint max_old_cset_length = calc_max_old_cset_length();
1980
1981 uint expensive_region_num = 0;
1982 bool check_time_remaining = adaptive_young_list_length();
1983
1984 HeapRegion* hr = cset_chooser->peek();
1985 while (hr != NULL) {
1986 if (old_cset_region_length() >= max_old_cset_length) {
1987 // Added maximum number of old regions to the CSet.
1988 ergo_verbose2(ErgoCSetConstruction,
1989 "finish adding old regions to CSet",
1990 ergo_format_reason("old CSet region num reached max")
1991 ergo_format_region("old")
1992 ergo_format_region("max"),
1993 old_cset_region_length(), max_old_cset_length);
1994 break;
1995 }
1996
1997
1998 // Stop adding regions if the remaining reclaimable space is
1999 // not above G1HeapWastePercent.
2000 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2001 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2002 double threshold = (double) G1HeapWastePercent;
2003 if (reclaimable_perc <= threshold) {
2004 // We've added enough old regions that the amount of uncollected
2005 // reclaimable space is at or below the waste threshold. Stop
2006 // adding old regions to the CSet.
2007 ergo_verbose5(ErgoCSetConstruction,
2008 "finish adding old regions to CSet",
2009 ergo_format_reason("reclaimable percentage not over threshold")
2010 ergo_format_region("old")
2011 ergo_format_region("max")
2012 ergo_format_byte_perc("reclaimable")
2013 ergo_format_perc("threshold"),
2014 old_cset_region_length(),
2015 max_old_cset_length,
2016 reclaimable_bytes,
2017 reclaimable_perc, threshold);
2018 break;
2019 }
2020
2021 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2022 if (check_time_remaining) {
2023 if (predicted_time_ms > time_remaining_ms) {
2024 // Too expensive for the current CSet.
2025
2026 if (old_cset_region_length() >= min_old_cset_length) {
2027 // We have added the minimum number of old regions to the CSet,
2028 // we are done with this CSet.
2029 ergo_verbose4(ErgoCSetConstruction,
2030 "finish adding old regions to CSet",
2031 ergo_format_reason("predicted time is too high")
2032 ergo_format_ms("predicted time")
2033 ergo_format_ms("remaining time")
2034 ergo_format_region("old")
2035 ergo_format_region("min"),
2036 predicted_time_ms, time_remaining_ms,
2037 old_cset_region_length(), min_old_cset_length);
2038 break;
2039 }
2040
2041 // We'll add it anyway given that we haven't reached the
2042 // minimum number of old regions.
2043 expensive_region_num += 1;
2044 }
2045 } else {
2046 if (old_cset_region_length() >= min_old_cset_length) {
2047 // In the non-auto-tuning case, we'll finish adding regions
2048 // to the CSet if we reach the minimum.
2049 ergo_verbose2(ErgoCSetConstruction,
2050 "finish adding old regions to CSet",
2051 ergo_format_reason("old CSet region num reached min")
2052 ergo_format_region("old")
2053 ergo_format_region("min"),
2054 old_cset_region_length(), min_old_cset_length);
2055 break;
2056 }
2057 }
2058
2059 // We will add this region to the CSet.
2060 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2061 predicted_pause_time_ms += predicted_time_ms;
2062 cset_chooser->remove_and_move_to_next(hr);
2063 _g1->old_set_remove(hr);
2064 add_old_region_to_cset(hr);
2065
2066 hr = cset_chooser->peek();
2067 }
2068 if (hr == NULL) {
2069 ergo_verbose0(ErgoCSetConstruction,
2070 "finish adding old regions to CSet",
2071 ergo_format_reason("candidate old regions not available"));
2072 }
2073
2074 if (expensive_region_num > 0) {
2075 // We print the information once here at the end, predicated on
2076 // whether we added any apparently expensive regions or not, to
2077 // avoid generating output per region.
2078 ergo_verbose4(ErgoCSetConstruction,
2079 "added expensive regions to CSet",
2080 ergo_format_reason("old CSet region num not reached min")
2081 ergo_format_region("old")
2082 ergo_format_region("expensive")
2083 ergo_format_region("min")
2084 ergo_format_ms("remaining time"),
2085 old_cset_region_length(),
2086 expensive_region_num,
2087 min_old_cset_length,
2088 time_remaining_ms);
2089 }
2090
2091 cset_chooser->verify();
2092 }
2093
2094 stop_incremental_cset_building();
2095
2096 ergo_verbose5(ErgoCSetConstruction,
2097 "finish choosing CSet",
2098 ergo_format_region("eden")
2099 ergo_format_region("survivors")
2100 ergo_format_region("old")
2101 ergo_format_ms("predicted pause time")
2102 ergo_format_ms("target pause time"),
2103 eden_region_length, survivor_region_length,
2104 old_cset_region_length(),
2105 predicted_pause_time_ms, target_pause_time_ms);
2106
2107 double non_young_end_time_sec = os::elapsedTime();
2108 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2109 evacuation_info.set_collectionset_regions(cset_region_length());
2110 }
2111
2112 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2113 if(TraceYoungGenTime) {
2114 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2115 }
2116 }
2117
2118 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2119 if(TraceYoungGenTime) {
2120 _all_yield_times_ms.add(yield_time_ms);
2121 }
2122 }
2123
2124 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2125 if(TraceYoungGenTime) {
2126 _total.add(pause_time_ms);
2127 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2128 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2129 _parallel.add(phase_times->cur_collection_par_time_ms());
2130 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2131 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2132 _update_rs.add(phase_times->average_last_update_rs_time());
2133 _scan_rs.add(phase_times->average_last_scan_rs_time());
2134 _obj_copy.add(phase_times->average_last_obj_copy_time());
2135 _termination.add(phase_times->average_last_termination_time());
2136
2137 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2138 phase_times->average_last_satb_filtering_times_ms() +
2139 phase_times->average_last_update_rs_time() +
2140 phase_times->average_last_scan_rs_time() +
2141 phase_times->average_last_obj_copy_time() +
2142 + phase_times->average_last_termination_time();
2143
2144 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2145 _parallel_other.add(parallel_other_time);
2146 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2147 }
2148 }
2149
2150 void TraceYoungGenTimeData::increment_young_collection_count() {
2151 if(TraceYoungGenTime) {
2152 ++_young_pause_num;
2153 }
2154 }
2155
2156 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2157 if(TraceYoungGenTime) {
2158 ++_mixed_pause_num;
2159 }
2160 }
2161
2162 void TraceYoungGenTimeData::print_summary(const char* str,
2163 const NumberSeq* seq) const {
2164 double sum = seq->sum();
2165 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2166 str, sum / 1000.0, seq->avg());
2167 }
2168
2169 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2170 const NumberSeq* seq) const {
2171 print_summary(str, seq);
2172 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2173 "(num", seq->num(), seq->sd(), seq->maximum());
2174 }
2175
2176 void TraceYoungGenTimeData::print() const {
2177 if (!TraceYoungGenTime) {
2178 return;
2179 }
2180
2181 gclog_or_tty->print_cr("ALL PAUSES");
2182 print_summary_sd(" Total", &_total);
2183 gclog_or_tty->cr();
2184 gclog_or_tty->cr();
2185 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2186 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2187 gclog_or_tty->cr();
2188
2189 gclog_or_tty->print_cr("EVACUATION PAUSES");
2190
2191 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2192 gclog_or_tty->print_cr("none");
2193 } else {
2194 print_summary_sd(" Evacuation Pauses", &_total);
2195 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2196 print_summary(" Parallel Time", &_parallel);
2197 print_summary(" Ext Root Scanning", &_ext_root_scan);
2198 print_summary(" SATB Filtering", &_satb_filtering);
2199 print_summary(" Update RS", &_update_rs);
2200 print_summary(" Scan RS", &_scan_rs);
2201 print_summary(" Object Copy", &_obj_copy);
2202 print_summary(" Termination", &_termination);
2203 print_summary(" Parallel Other", &_parallel_other);
2204 print_summary(" Clear CT", &_clear_ct);
2205 print_summary(" Other", &_other);
2206 }
2207 gclog_or_tty->cr();
2208
2209 gclog_or_tty->print_cr("MISC");
2210 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2211 print_summary_sd(" Yields", &_all_yield_times_ms);
2212 }
2213
2214 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2215 if (TraceOldGenTime) {
2216 _all_full_gc_times.add(full_gc_time_ms);
2217 }
2218 }
2219
2220 void TraceOldGenTimeData::print() const {
2221 if (!TraceOldGenTime) {
2222 return;
2223 }
2224
2225 if (_all_full_gc_times.num() > 0) {
2226 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2227 _all_full_gc_times.num(),
2228 _all_full_gc_times.sum() / 1000.0);
2229 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2230 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2231 _all_full_gc_times.sd(),
2232 _all_full_gc_times.maximum());
2233 }
2234 }