1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
33 #include "gc_implementation/g1/g1Log.hpp"
34 #include "gc_implementation/g1/heapRegionRemSet.hpp"
35 #include "gc_implementation/shared/gcPolicyCounters.hpp"
36 #include "runtime/arguments.hpp"
37 #include "runtime/java.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "utilities/debug.hpp"
40
41 // Different defaults for different number of GC threads
42 // They were chosen by running GCOld and SPECjbb on debris with different
43 // numbers of GC threads and choosing them based on the results
44
45 // all the same
46 static double rs_length_diff_defaults[] = {
47 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
48 };
49
50 static double cost_per_card_ms_defaults[] = {
51 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
52 };
53
54 // all the same
55 static double young_cards_per_entry_ratio_defaults[] = {
56 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
57 };
58
59 static double cost_per_entry_ms_defaults[] = {
60 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
61 };
62
63 static double cost_per_byte_ms_defaults[] = {
64 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
65 };
66
67 // these should be pretty consistent
68 static double constant_other_time_ms_defaults[] = {
69 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
70 };
71
72
73 static double young_other_cost_per_region_ms_defaults[] = {
74 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
75 };
76
77 static double non_young_other_cost_per_region_ms_defaults[] = {
78 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
79 };
80
81 G1CollectorPolicy::G1CollectorPolicy() :
82 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
83 ? ParallelGCThreads : 1),
84
85 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
86 _stop_world_start(0.0),
87
88 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
89 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
90
91 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
92 _prev_collection_pause_end_ms(0.0),
93 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
94 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
95 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
96 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
97 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _non_young_other_cost_per_region_ms_seq(
104 new TruncatedSeq(TruncatedSeqLength)),
105
106 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
108
109 _pause_time_target_ms((double) MaxGCPauseMillis),
110
111 _gcs_are_young(true),
112
113 _during_marking(false),
114 _in_marking_window(false),
115 _in_marking_window_im(false),
116
117 _recent_prev_end_times_for_all_gcs_sec(
118 new TruncatedSeq(NumPrevPausesForHeuristics)),
119
120 _recent_avg_pause_time_ratio(0.0),
121
122 _initiate_conc_mark_if_possible(false),
123 _during_initial_mark_pause(false),
124 _last_young_gc(false),
125 _last_gc_was_young(false),
126
127 _eden_used_bytes_before_gc(0),
128 _survivor_used_bytes_before_gc(0),
129 _heap_used_bytes_before_gc(0),
130 _metaspace_used_bytes_before_gc(0),
131 _eden_capacity_bytes_before_gc(0),
132 _heap_capacity_bytes_before_gc(0),
133
134 _eden_cset_region_length(0),
135 _survivor_cset_region_length(0),
136 _old_cset_region_length(0),
137
138 _collection_set(NULL),
139 _collection_set_bytes_used_before(0),
140
141 // Incremental CSet attributes
142 _inc_cset_build_state(Inactive),
143 _inc_cset_head(NULL),
144 _inc_cset_tail(NULL),
145 _inc_cset_bytes_used_before(0),
146 _inc_cset_max_finger(NULL),
147 _inc_cset_recorded_rs_lengths(0),
148 _inc_cset_recorded_rs_lengths_diffs(0),
149 _inc_cset_predicted_elapsed_time_ms(0.0),
150 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
151
152 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
153 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
154 #endif // _MSC_VER
155
156 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
157 G1YoungSurvRateNumRegionsSummary)),
158 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
159 G1YoungSurvRateNumRegionsSummary)),
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 // Set up the region size and associated fields. Given that the
169 // policy is created before the heap, we have to set this up here,
170 // so it's done as soon as possible.
171
172 // It would have been natural to pass initial_heap_byte_size() and
173 // max_heap_byte_size() to setup_heap_region_size() but those have
174 // not been set up at this point since they should be aligned with
175 // the region size. So, there is a circular dependency here. We base
176 // the region size on the heap size, but the heap size should be
177 // aligned with the region size. To get around this we use the
178 // unaligned values for the heap.
179 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
180 HeapRegionRemSet::setup_remset_size();
181
182 G1ErgoVerbose::initialize();
183 if (PrintAdaptiveSizePolicy) {
184 // Currently, we only use a single switch for all the heuristics.
185 G1ErgoVerbose::set_enabled(true);
186 // Given that we don't currently have a verboseness level
187 // parameter, we'll hardcode this to high. This can be easily
188 // changed in the future.
189 G1ErgoVerbose::set_level(ErgoHigh);
190 } else {
191 G1ErgoVerbose::set_enabled(false);
192 }
193
194 // Verify PLAB sizes
195 const size_t region_size = HeapRegion::GrainWords;
196 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
197 char buffer[128];
198 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
199 OldPLABSize > region_size ? "Old" : "Young", region_size);
200 vm_exit_during_initialization(buffer);
201 }
202
203 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
204 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
205
206 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
207
208 int index = MIN2(_parallel_gc_threads - 1, 7);
209
210 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
211 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
212 _young_cards_per_entry_ratio_seq->add(
213 young_cards_per_entry_ratio_defaults[index]);
214 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
215 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
216 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
217 _young_other_cost_per_region_ms_seq->add(
218 young_other_cost_per_region_ms_defaults[index]);
219 _non_young_other_cost_per_region_ms_seq->add(
220 non_young_other_cost_per_region_ms_defaults[index]);
221
222 // Below, we might need to calculate the pause time target based on
223 // the pause interval. When we do so we are going to give G1 maximum
224 // flexibility and allow it to do pauses when it needs to. So, we'll
225 // arrange that the pause interval to be pause time target + 1 to
226 // ensure that a) the pause time target is maximized with respect to
227 // the pause interval and b) we maintain the invariant that pause
228 // time target < pause interval. If the user does not want this
229 // maximum flexibility, they will have to set the pause interval
230 // explicitly.
231
232 // First make sure that, if either parameter is set, its value is
233 // reasonable.
234 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
235 if (MaxGCPauseMillis < 1) {
236 vm_exit_during_initialization("MaxGCPauseMillis should be "
237 "greater than 0");
238 }
239 }
240 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
241 if (GCPauseIntervalMillis < 1) {
242 vm_exit_during_initialization("GCPauseIntervalMillis should be "
243 "greater than 0");
244 }
245 }
246
247 // Then, if the pause time target parameter was not set, set it to
248 // the default value.
249 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
250 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
251 // The default pause time target in G1 is 200ms
252 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
253 } else {
254 // We do not allow the pause interval to be set without the
255 // pause time target
256 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
257 "without setting MaxGCPauseMillis");
258 }
259 }
260
261 // Then, if the interval parameter was not set, set it according to
262 // the pause time target (this will also deal with the case when the
263 // pause time target is the default value).
264 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
265 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
266 }
267
268 // Finally, make sure that the two parameters are consistent.
269 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
270 char buffer[256];
271 jio_snprintf(buffer, 256,
272 "MaxGCPauseMillis (%u) should be less than "
273 "GCPauseIntervalMillis (%u)",
274 MaxGCPauseMillis, GCPauseIntervalMillis);
275 vm_exit_during_initialization(buffer);
276 }
277
278 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
279 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
280 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
281
282 uintx confidence_perc = G1ConfidencePercent;
283 // Put an artificial ceiling on this so that it's not set to a silly value.
284 if (confidence_perc > 100) {
285 confidence_perc = 100;
286 warning("G1ConfidencePercent is set to a value that is too large, "
287 "it's been updated to %u", confidence_perc);
288 }
289 _sigma = (double) confidence_perc / 100.0;
290
291 // start conservatively (around 50ms is about right)
292 _concurrent_mark_remark_times_ms->add(0.05);
293 _concurrent_mark_cleanup_times_ms->add(0.20);
294 _tenuring_threshold = MaxTenuringThreshold;
295 // _max_survivor_regions will be calculated by
296 // update_young_list_target_length() during initialization.
297 _max_survivor_regions = 0;
298
299 assert(GCTimeRatio > 0,
300 "we should have set it to a default value set_g1_gc_flags() "
301 "if a user set it to 0");
302 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
303
304 uintx reserve_perc = G1ReservePercent;
305 // Put an artificial ceiling on this so that it's not set to a silly value.
306 if (reserve_perc > 50) {
307 reserve_perc = 50;
308 warning("G1ReservePercent is set to a value that is too large, "
309 "it's been updated to %u", reserve_perc);
310 }
311 _reserve_factor = (double) reserve_perc / 100.0;
312 // This will be set when the heap is expanded
313 // for the first time during initialization.
314 _reserve_regions = 0;
315
316 initialize_all();
317 _collectionSetChooser = new CollectionSetChooser();
318 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
319 }
320
321 void G1CollectorPolicy::initialize_flags() {
322 _min_alignment = HeapRegion::GrainBytes;
323 size_t card_table_alignment = GenRemSet::max_alignment_constraint(rem_set_name());
324 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
325 _max_alignment = MAX3(card_table_alignment, _min_alignment, page_size);
326 if (SurvivorRatio < 1) {
327 vm_exit_during_initialization("Invalid survivor ratio specified");
328 }
329 CollectorPolicy::initialize_flags();
330 }
331
332 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
333 assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max");
334 assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds");
335 assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds");
336
337 if (FLAG_IS_CMDLINE(NewRatio)) {
338 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
339 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
340 } else {
341 _sizer_kind = SizerNewRatio;
342 _adaptive_size = false;
343 return;
344 }
345 }
346
347 if (FLAG_IS_CMDLINE(NewSize)) {
348 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
349 1U);
350 if (FLAG_IS_CMDLINE(MaxNewSize)) {
351 _max_desired_young_length =
352 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
353 1U);
354 _sizer_kind = SizerMaxAndNewSize;
355 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
356 } else {
357 _sizer_kind = SizerNewSizeOnly;
358 }
359 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
360 _max_desired_young_length =
361 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
362 1U);
363 _sizer_kind = SizerMaxNewSizeOnly;
364 }
365 }
366
367 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
368 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
369 return MAX2(1U, default_value);
370 }
371
372 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
373 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
374 return MAX2(1U, default_value);
375 }
376
377 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
378 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
379
380 switch (_sizer_kind) {
381 case SizerDefaults:
382 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
383 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
384 break;
385 case SizerNewSizeOnly:
386 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
387 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
388 break;
389 case SizerMaxNewSizeOnly:
390 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
391 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
392 break;
393 case SizerMaxAndNewSize:
394 // Do nothing. Values set on the command line, don't update them at runtime.
395 break;
396 case SizerNewRatio:
397 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
398 _max_desired_young_length = _min_desired_young_length;
399 break;
400 default:
401 ShouldNotReachHere();
402 }
403
404 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
405 }
406
407 void G1CollectorPolicy::init() {
408 // Set aside an initial future to_space.
409 _g1 = G1CollectedHeap::heap();
410
411 assert(Heap_lock->owned_by_self(), "Locking discipline.");
412
413 initialize_gc_policy_counters();
414
415 if (adaptive_young_list_length()) {
416 _young_list_fixed_length = 0;
417 } else {
418 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
419 }
420 _free_regions_at_end_of_collection = _g1->free_regions();
421 update_young_list_target_length();
422
423 // We may immediately start allocating regions and placing them on the
424 // collection set list. Initialize the per-collection set info
425 start_incremental_cset_building();
426 }
427
428 // Create the jstat counters for the policy.
429 void G1CollectorPolicy::initialize_gc_policy_counters() {
430 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
431 }
432
433 bool G1CollectorPolicy::predict_will_fit(uint young_length,
434 double base_time_ms,
435 uint base_free_regions,
436 double target_pause_time_ms) {
437 if (young_length >= base_free_regions) {
438 // end condition 1: not enough space for the young regions
439 return false;
440 }
441
442 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
443 size_t bytes_to_copy =
444 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
445 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
446 double young_other_time_ms = predict_young_other_time_ms(young_length);
447 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
448 if (pause_time_ms > target_pause_time_ms) {
449 // end condition 2: prediction is over the target pause time
450 return false;
451 }
452
453 size_t free_bytes =
454 (base_free_regions - young_length) * HeapRegion::GrainBytes;
455 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
456 // end condition 3: out-of-space (conservatively!)
457 return false;
458 }
459
460 // success!
461 return true;
462 }
463
464 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
465 // re-calculate the necessary reserve
466 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
467 // We use ceiling so that if reserve_regions_d is > 0.0 (but
468 // smaller than 1.0) we'll get 1.
469 _reserve_regions = (uint) ceil(reserve_regions_d);
470
471 _young_gen_sizer->heap_size_changed(new_number_of_regions);
472 }
473
474 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
475 uint base_min_length) {
476 uint desired_min_length = 0;
477 if (adaptive_young_list_length()) {
478 if (_alloc_rate_ms_seq->num() > 3) {
479 double now_sec = os::elapsedTime();
480 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
481 double alloc_rate_ms = predict_alloc_rate_ms();
482 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
483 } else {
484 // otherwise we don't have enough info to make the prediction
485 }
486 }
487 desired_min_length += base_min_length;
488 // make sure we don't go below any user-defined minimum bound
489 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
490 }
491
492 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
493 // Here, we might want to also take into account any additional
494 // constraints (i.e., user-defined minimum bound). Currently, we
495 // effectively don't set this bound.
496 return _young_gen_sizer->max_desired_young_length();
497 }
498
499 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
500 if (rs_lengths == (size_t) -1) {
501 // if it's set to the default value (-1), we should predict it;
502 // otherwise, use the given value.
503 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
504 }
505
506 // Calculate the absolute and desired min bounds.
507
508 // This is how many young regions we already have (currently: the survivors).
509 uint base_min_length = recorded_survivor_regions();
510 // This is the absolute minimum young length, which ensures that we
511 // can allocate one eden region in the worst-case.
512 uint absolute_min_length = base_min_length + 1;
513 uint desired_min_length =
514 calculate_young_list_desired_min_length(base_min_length);
515 if (desired_min_length < absolute_min_length) {
516 desired_min_length = absolute_min_length;
517 }
518
519 // Calculate the absolute and desired max bounds.
520
521 // We will try our best not to "eat" into the reserve.
522 uint absolute_max_length = 0;
523 if (_free_regions_at_end_of_collection > _reserve_regions) {
524 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
525 }
526 uint desired_max_length = calculate_young_list_desired_max_length();
527 if (desired_max_length > absolute_max_length) {
528 desired_max_length = absolute_max_length;
529 }
530
531 uint young_list_target_length = 0;
532 if (adaptive_young_list_length()) {
533 if (gcs_are_young()) {
534 young_list_target_length =
535 calculate_young_list_target_length(rs_lengths,
536 base_min_length,
537 desired_min_length,
538 desired_max_length);
539 _rs_lengths_prediction = rs_lengths;
540 } else {
541 // Don't calculate anything and let the code below bound it to
542 // the desired_min_length, i.e., do the next GC as soon as
543 // possible to maximize how many old regions we can add to it.
544 }
545 } else {
546 // The user asked for a fixed young gen so we'll fix the young gen
547 // whether the next GC is young or mixed.
548 young_list_target_length = _young_list_fixed_length;
549 }
550
551 // Make sure we don't go over the desired max length, nor under the
552 // desired min length. In case they clash, desired_min_length wins
553 // which is why that test is second.
554 if (young_list_target_length > desired_max_length) {
555 young_list_target_length = desired_max_length;
556 }
557 if (young_list_target_length < desired_min_length) {
558 young_list_target_length = desired_min_length;
559 }
560
561 assert(young_list_target_length > recorded_survivor_regions(),
562 "we should be able to allocate at least one eden region");
563 assert(young_list_target_length >= absolute_min_length, "post-condition");
564 _young_list_target_length = young_list_target_length;
565
566 update_max_gc_locker_expansion();
567 }
568
569 uint
570 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
571 uint base_min_length,
572 uint desired_min_length,
573 uint desired_max_length) {
574 assert(adaptive_young_list_length(), "pre-condition");
575 assert(gcs_are_young(), "only call this for young GCs");
576
577 // In case some edge-condition makes the desired max length too small...
578 if (desired_max_length <= desired_min_length) {
579 return desired_min_length;
580 }
581
582 // We'll adjust min_young_length and max_young_length not to include
583 // the already allocated young regions (i.e., so they reflect the
584 // min and max eden regions we'll allocate). The base_min_length
585 // will be reflected in the predictions by the
586 // survivor_regions_evac_time prediction.
587 assert(desired_min_length > base_min_length, "invariant");
588 uint min_young_length = desired_min_length - base_min_length;
589 assert(desired_max_length > base_min_length, "invariant");
590 uint max_young_length = desired_max_length - base_min_length;
591
592 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
593 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
594 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
595 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
596 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
597 double base_time_ms =
598 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
599 survivor_regions_evac_time;
600 uint available_free_regions = _free_regions_at_end_of_collection;
601 uint base_free_regions = 0;
602 if (available_free_regions > _reserve_regions) {
603 base_free_regions = available_free_regions - _reserve_regions;
604 }
605
606 // Here, we will make sure that the shortest young length that
607 // makes sense fits within the target pause time.
608
609 if (predict_will_fit(min_young_length, base_time_ms,
610 base_free_regions, target_pause_time_ms)) {
611 // The shortest young length will fit into the target pause time;
612 // we'll now check whether the absolute maximum number of young
613 // regions will fit in the target pause time. If not, we'll do
614 // a binary search between min_young_length and max_young_length.
615 if (predict_will_fit(max_young_length, base_time_ms,
616 base_free_regions, target_pause_time_ms)) {
617 // The maximum young length will fit into the target pause time.
618 // We are done so set min young length to the maximum length (as
619 // the result is assumed to be returned in min_young_length).
620 min_young_length = max_young_length;
621 } else {
622 // The maximum possible number of young regions will not fit within
623 // the target pause time so we'll search for the optimal
624 // length. The loop invariants are:
625 //
626 // min_young_length < max_young_length
627 // min_young_length is known to fit into the target pause time
628 // max_young_length is known not to fit into the target pause time
629 //
630 // Going into the loop we know the above hold as we've just
631 // checked them. Every time around the loop we check whether
632 // the middle value between min_young_length and
633 // max_young_length fits into the target pause time. If it
634 // does, it becomes the new min. If it doesn't, it becomes
635 // the new max. This way we maintain the loop invariants.
636
637 assert(min_young_length < max_young_length, "invariant");
638 uint diff = (max_young_length - min_young_length) / 2;
639 while (diff > 0) {
640 uint young_length = min_young_length + diff;
641 if (predict_will_fit(young_length, base_time_ms,
642 base_free_regions, target_pause_time_ms)) {
643 min_young_length = young_length;
644 } else {
645 max_young_length = young_length;
646 }
647 assert(min_young_length < max_young_length, "invariant");
648 diff = (max_young_length - min_young_length) / 2;
649 }
650 // The results is min_young_length which, according to the
651 // loop invariants, should fit within the target pause time.
652
653 // These are the post-conditions of the binary search above:
654 assert(min_young_length < max_young_length,
655 "otherwise we should have discovered that max_young_length "
656 "fits into the pause target and not done the binary search");
657 assert(predict_will_fit(min_young_length, base_time_ms,
658 base_free_regions, target_pause_time_ms),
659 "min_young_length, the result of the binary search, should "
660 "fit into the pause target");
661 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
662 base_free_regions, target_pause_time_ms),
663 "min_young_length, the result of the binary search, should be "
664 "optimal, so no larger length should fit into the pause target");
665 }
666 } else {
667 // Even the minimum length doesn't fit into the pause time
668 // target, return it as the result nevertheless.
669 }
670 return base_min_length + min_young_length;
671 }
672
673 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
674 double survivor_regions_evac_time = 0.0;
675 for (HeapRegion * r = _recorded_survivor_head;
676 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
677 r = r->get_next_young_region()) {
678 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
679 }
680 return survivor_regions_evac_time;
681 }
682
683 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
684 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
685
686 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
687 if (rs_lengths > _rs_lengths_prediction) {
688 // add 10% to avoid having to recalculate often
689 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
690 update_young_list_target_length(rs_lengths_prediction);
691 }
692 }
693
694
695
696 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
697 bool is_tlab,
698 bool* gc_overhead_limit_was_exceeded) {
699 guarantee(false, "Not using this policy feature yet.");
700 return NULL;
701 }
702
703 // This method controls how a collector handles one or more
704 // of its generations being fully allocated.
705 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
706 bool is_tlab) {
707 guarantee(false, "Not using this policy feature yet.");
708 return NULL;
709 }
710
711
712 #ifndef PRODUCT
713 bool G1CollectorPolicy::verify_young_ages() {
714 HeapRegion* head = _g1->young_list()->first_region();
715 return
716 verify_young_ages(head, _short_lived_surv_rate_group);
717 // also call verify_young_ages on any additional surv rate groups
718 }
719
720 bool
721 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
722 SurvRateGroup *surv_rate_group) {
723 guarantee( surv_rate_group != NULL, "pre-condition" );
724
725 const char* name = surv_rate_group->name();
726 bool ret = true;
727 int prev_age = -1;
728
729 for (HeapRegion* curr = head;
730 curr != NULL;
731 curr = curr->get_next_young_region()) {
732 SurvRateGroup* group = curr->surv_rate_group();
733 if (group == NULL && !curr->is_survivor()) {
734 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
735 ret = false;
736 }
737
738 if (surv_rate_group == group) {
739 int age = curr->age_in_surv_rate_group();
740
741 if (age < 0) {
742 gclog_or_tty->print_cr("## %s: encountered negative age", name);
743 ret = false;
744 }
745
746 if (age <= prev_age) {
747 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
748 "(%d, %d)", name, age, prev_age);
749 ret = false;
750 }
751 prev_age = age;
752 }
753 }
754
755 return ret;
756 }
757 #endif // PRODUCT
758
759 void G1CollectorPolicy::record_full_collection_start() {
760 _full_collection_start_sec = os::elapsedTime();
761 record_heap_size_info_at_start(true /* full */);
762 // Release the future to-space so that it is available for compaction into.
763 _g1->set_full_collection();
764 }
765
766 void G1CollectorPolicy::record_full_collection_end() {
767 // Consider this like a collection pause for the purposes of allocation
768 // since last pause.
769 double end_sec = os::elapsedTime();
770 double full_gc_time_sec = end_sec - _full_collection_start_sec;
771 double full_gc_time_ms = full_gc_time_sec * 1000.0;
772
773 _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
774
775 update_recent_gc_times(end_sec, full_gc_time_ms);
776
777 _g1->clear_full_collection();
778
779 // "Nuke" the heuristics that control the young/mixed GC
780 // transitions and make sure we start with young GCs after the Full GC.
781 set_gcs_are_young(true);
782 _last_young_gc = false;
783 clear_initiate_conc_mark_if_possible();
784 clear_during_initial_mark_pause();
785 _in_marking_window = false;
786 _in_marking_window_im = false;
787
788 _short_lived_surv_rate_group->start_adding_regions();
789 // also call this on any additional surv rate groups
790
791 record_survivor_regions(0, NULL, NULL);
792
793 _free_regions_at_end_of_collection = _g1->free_regions();
794 // Reset survivors SurvRateGroup.
795 _survivor_surv_rate_group->reset();
796 update_young_list_target_length();
797 _collectionSetChooser->clear();
798 }
799
800 void G1CollectorPolicy::record_stop_world_start() {
801 _stop_world_start = os::elapsedTime();
802 }
803
804 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
805 // We only need to do this here as the policy will only be applied
806 // to the GC we're about to start. so, no point is calculating this
807 // every time we calculate / recalculate the target young length.
808 update_survivors_policy();
809
810 assert(_g1->used() == _g1->recalculate_used(),
811 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
812 _g1->used(), _g1->recalculate_used()));
813
814 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
815 _trace_gen0_time_data.record_start_collection(s_w_t_ms);
816 _stop_world_start = 0.0;
817
818 record_heap_size_info_at_start(false /* full */);
819
820 phase_times()->record_cur_collection_start_sec(start_time_sec);
821 _pending_cards = _g1->pending_card_num();
822
823 _collection_set_bytes_used_before = 0;
824 _bytes_copied_during_gc = 0;
825
826 _last_gc_was_young = false;
827
828 // do that for any other surv rate groups
829 _short_lived_surv_rate_group->stop_adding_regions();
830 _survivors_age_table.clear();
831
832 assert( verify_young_ages(), "region age verification" );
833 }
834
835 void G1CollectorPolicy::record_concurrent_mark_init_end(double
836 mark_init_elapsed_time_ms) {
837 _during_marking = true;
838 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
839 clear_during_initial_mark_pause();
840 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
841 }
842
843 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
844 _mark_remark_start_sec = os::elapsedTime();
845 _during_marking = false;
846 }
847
848 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
849 double end_time_sec = os::elapsedTime();
850 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
851 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
852 _cur_mark_stop_world_time_ms += elapsed_time_ms;
853 _prev_collection_pause_end_ms += elapsed_time_ms;
854
855 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
856 }
857
858 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
859 _mark_cleanup_start_sec = os::elapsedTime();
860 }
861
862 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
863 _last_young_gc = true;
864 _in_marking_window = false;
865 }
866
867 void G1CollectorPolicy::record_concurrent_pause() {
868 if (_stop_world_start > 0.0) {
869 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
870 _trace_gen0_time_data.record_yield_time(yield_ms);
871 }
872 }
873
874 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
875 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
876 return false;
877 }
878
879 size_t marking_initiating_used_threshold =
880 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
881 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
882 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
883
884 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
885 if (gcs_are_young() && !_last_young_gc) {
886 ergo_verbose5(ErgoConcCycles,
887 "request concurrent cycle initiation",
888 ergo_format_reason("occupancy higher than threshold")
889 ergo_format_byte("occupancy")
890 ergo_format_byte("allocation request")
891 ergo_format_byte_perc("threshold")
892 ergo_format_str("source"),
893 cur_used_bytes,
894 alloc_byte_size,
895 marking_initiating_used_threshold,
896 (double) InitiatingHeapOccupancyPercent,
897 source);
898 return true;
899 } else {
900 ergo_verbose5(ErgoConcCycles,
901 "do not request concurrent cycle initiation",
902 ergo_format_reason("still doing mixed collections")
903 ergo_format_byte("occupancy")
904 ergo_format_byte("allocation request")
905 ergo_format_byte_perc("threshold")
906 ergo_format_str("source"),
907 cur_used_bytes,
908 alloc_byte_size,
909 marking_initiating_used_threshold,
910 (double) InitiatingHeapOccupancyPercent,
911 source);
912 }
913 }
914
915 return false;
916 }
917
918 // Anything below that is considered to be zero
919 #define MIN_TIMER_GRANULARITY 0.0000001
920
921 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
922 double end_time_sec = os::elapsedTime();
923 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
924 "otherwise, the subtraction below does not make sense");
925 size_t rs_size =
926 _cur_collection_pause_used_regions_at_start - cset_region_length();
927 size_t cur_used_bytes = _g1->used();
928 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
929 bool last_pause_included_initial_mark = false;
930 bool update_stats = !_g1->evacuation_failed();
931
932 #ifndef PRODUCT
933 if (G1YoungSurvRateVerbose) {
934 gclog_or_tty->print_cr("");
935 _short_lived_surv_rate_group->print();
936 // do that for any other surv rate groups too
937 }
938 #endif // PRODUCT
939
940 last_pause_included_initial_mark = during_initial_mark_pause();
941 if (last_pause_included_initial_mark) {
942 record_concurrent_mark_init_end(0.0);
943 } else if (need_to_start_conc_mark("end of GC")) {
944 // Note: this might have already been set, if during the last
945 // pause we decided to start a cycle but at the beginning of
946 // this pause we decided to postpone it. That's OK.
947 set_initiate_conc_mark_if_possible();
948 }
949
950 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
951 end_time_sec, false);
952
953 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
954 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
955
956 if (update_stats) {
957 _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
958 // this is where we update the allocation rate of the application
959 double app_time_ms =
960 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
961 if (app_time_ms < MIN_TIMER_GRANULARITY) {
962 // This usually happens due to the timer not having the required
963 // granularity. Some Linuxes are the usual culprits.
964 // We'll just set it to something (arbitrarily) small.
965 app_time_ms = 1.0;
966 }
967 // We maintain the invariant that all objects allocated by mutator
968 // threads will be allocated out of eden regions. So, we can use
969 // the eden region number allocated since the previous GC to
970 // calculate the application's allocate rate. The only exception
971 // to that is humongous objects that are allocated separately. But
972 // given that humongous object allocations do not really affect
973 // either the pause's duration nor when the next pause will take
974 // place we can safely ignore them here.
975 uint regions_allocated = eden_cset_region_length();
976 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
977 _alloc_rate_ms_seq->add(alloc_rate_ms);
978
979 double interval_ms =
980 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
981 update_recent_gc_times(end_time_sec, pause_time_ms);
982 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
983 if (recent_avg_pause_time_ratio() < 0.0 ||
984 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
985 #ifndef PRODUCT
986 // Dump info to allow post-facto debugging
987 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
988 gclog_or_tty->print_cr("-------------------------------------------");
989 gclog_or_tty->print_cr("Recent GC Times (ms):");
990 _recent_gc_times_ms->dump();
991 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
992 _recent_prev_end_times_for_all_gcs_sec->dump();
993 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
994 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
995 // In debug mode, terminate the JVM if the user wants to debug at this point.
996 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
997 #endif // !PRODUCT
998 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
999 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1000 if (_recent_avg_pause_time_ratio < 0.0) {
1001 _recent_avg_pause_time_ratio = 0.0;
1002 } else {
1003 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1004 _recent_avg_pause_time_ratio = 1.0;
1005 }
1006 }
1007 }
1008
1009 bool new_in_marking_window = _in_marking_window;
1010 bool new_in_marking_window_im = false;
1011 if (during_initial_mark_pause()) {
1012 new_in_marking_window = true;
1013 new_in_marking_window_im = true;
1014 }
1015
1016 if (_last_young_gc) {
1017 // This is supposed to to be the "last young GC" before we start
1018 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1019
1020 if (!last_pause_included_initial_mark) {
1021 if (next_gc_should_be_mixed("start mixed GCs",
1022 "do not start mixed GCs")) {
1023 set_gcs_are_young(false);
1024 }
1025 } else {
1026 ergo_verbose0(ErgoMixedGCs,
1027 "do not start mixed GCs",
1028 ergo_format_reason("concurrent cycle is about to start"));
1029 }
1030 _last_young_gc = false;
1031 }
1032
1033 if (!_last_gc_was_young) {
1034 // This is a mixed GC. Here we decide whether to continue doing
1035 // mixed GCs or not.
1036
1037 if (!next_gc_should_be_mixed("continue mixed GCs",
1038 "do not continue mixed GCs")) {
1039 set_gcs_are_young(true);
1040 }
1041 }
1042
1043 _short_lived_surv_rate_group->start_adding_regions();
1044 // do that for any other surv rate groupsx
1045
1046 if (update_stats) {
1047 double cost_per_card_ms = 0.0;
1048 if (_pending_cards > 0) {
1049 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1050 _cost_per_card_ms_seq->add(cost_per_card_ms);
1051 }
1052
1053 size_t cards_scanned = _g1->cards_scanned();
1054
1055 double cost_per_entry_ms = 0.0;
1056 if (cards_scanned > 10) {
1057 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1058 if (_last_gc_was_young) {
1059 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1060 } else {
1061 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1062 }
1063 }
1064
1065 if (_max_rs_lengths > 0) {
1066 double cards_per_entry_ratio =
1067 (double) cards_scanned / (double) _max_rs_lengths;
1068 if (_last_gc_was_young) {
1069 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1070 } else {
1071 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1072 }
1073 }
1074
1075 // This is defensive. For a while _max_rs_lengths could get
1076 // smaller than _recorded_rs_lengths which was causing
1077 // rs_length_diff to get very large and mess up the RSet length
1078 // predictions. The reason was unsafe concurrent updates to the
1079 // _inc_cset_recorded_rs_lengths field which the code below guards
1080 // against (see CR 7118202). This bug has now been fixed (see CR
1081 // 7119027). However, I'm still worried that
1082 // _inc_cset_recorded_rs_lengths might still end up somewhat
1083 // inaccurate. The concurrent refinement thread calculates an
1084 // RSet's length concurrently with other CR threads updating it
1085 // which might cause it to calculate the length incorrectly (if,
1086 // say, it's in mid-coarsening). So I'll leave in the defensive
1087 // conditional below just in case.
1088 size_t rs_length_diff = 0;
1089 if (_max_rs_lengths > _recorded_rs_lengths) {
1090 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1091 }
1092 _rs_length_diff_seq->add((double) rs_length_diff);
1093
1094 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1095 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1096 double cost_per_byte_ms = 0.0;
1097
1098 if (copied_bytes > 0) {
1099 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1100 if (_in_marking_window) {
1101 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1102 } else {
1103 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1104 }
1105 }
1106
1107 double all_other_time_ms = pause_time_ms -
1108 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1109 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1110
1111 double young_other_time_ms = 0.0;
1112 if (young_cset_region_length() > 0) {
1113 young_other_time_ms =
1114 phase_times()->young_cset_choice_time_ms() +
1115 phase_times()->young_free_cset_time_ms();
1116 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1117 (double) young_cset_region_length());
1118 }
1119 double non_young_other_time_ms = 0.0;
1120 if (old_cset_region_length() > 0) {
1121 non_young_other_time_ms =
1122 phase_times()->non_young_cset_choice_time_ms() +
1123 phase_times()->non_young_free_cset_time_ms();
1124
1125 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1126 (double) old_cset_region_length());
1127 }
1128
1129 double constant_other_time_ms = all_other_time_ms -
1130 (young_other_time_ms + non_young_other_time_ms);
1131 _constant_other_time_ms_seq->add(constant_other_time_ms);
1132
1133 double survival_ratio = 0.0;
1134 if (_collection_set_bytes_used_before > 0) {
1135 survival_ratio = (double) _bytes_copied_during_gc /
1136 (double) _collection_set_bytes_used_before;
1137 }
1138
1139 _pending_cards_seq->add((double) _pending_cards);
1140 _rs_lengths_seq->add((double) _max_rs_lengths);
1141 }
1142
1143 _in_marking_window = new_in_marking_window;
1144 _in_marking_window_im = new_in_marking_window_im;
1145 _free_regions_at_end_of_collection = _g1->free_regions();
1146 update_young_list_target_length();
1147
1148 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1149 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1150 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1151 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1152
1153 _collectionSetChooser->verify();
1154 }
1155
1156 #define EXT_SIZE_FORMAT "%.1f%s"
1157 #define EXT_SIZE_PARAMS(bytes) \
1158 byte_size_in_proper_unit((double)(bytes)), \
1159 proper_unit_for_byte_size((bytes))
1160
1161 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1162 YoungList* young_list = _g1->young_list();
1163 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1164 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1165 _heap_capacity_bytes_before_gc = _g1->capacity();
1166 _heap_used_bytes_before_gc = _g1->used();
1167 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
1168
1169 _eden_capacity_bytes_before_gc =
1170 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1171
1172 if (full) {
1173 _metaspace_used_bytes_before_gc = MetaspaceAux::allocated_used_bytes();
1174 }
1175 }
1176
1177 void G1CollectorPolicy::print_heap_transition() {
1178 _g1->print_size_transition(gclog_or_tty,
1179 _heap_used_bytes_before_gc,
1180 _g1->used(),
1181 _g1->capacity());
1182 }
1183
1184 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {
1185 YoungList* young_list = _g1->young_list();
1186
1187 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1188 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1189 size_t heap_used_bytes_after_gc = _g1->used();
1190
1191 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1192 size_t eden_capacity_bytes_after_gc =
1193 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1194
1195 gclog_or_tty->print(
1196 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1197 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1198 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1199 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1200 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1201 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1202 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1203 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1204 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1205 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1206 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1207 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1208 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1209 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1210
1211 if (full) {
1212 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1213 }
1214
1215 gclog_or_tty->cr();
1216 }
1217
1218 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1219 double update_rs_processed_buffers,
1220 double goal_ms) {
1221 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1222 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1223
1224 if (G1UseAdaptiveConcRefinement) {
1225 const int k_gy = 3, k_gr = 6;
1226 const double inc_k = 1.1, dec_k = 0.9;
1227
1228 int g = cg1r->green_zone();
1229 if (update_rs_time > goal_ms) {
1230 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1231 } else {
1232 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1233 g = (int)MAX2(g * inc_k, g + 1.0);
1234 }
1235 }
1236 // Change the refinement threads params
1237 cg1r->set_green_zone(g);
1238 cg1r->set_yellow_zone(g * k_gy);
1239 cg1r->set_red_zone(g * k_gr);
1240 cg1r->reinitialize_threads();
1241
1242 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1243 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1244 cg1r->yellow_zone());
1245 // Change the barrier params
1246 dcqs.set_process_completed_threshold(processing_threshold);
1247 dcqs.set_max_completed_queue(cg1r->red_zone());
1248 }
1249
1250 int curr_queue_size = dcqs.completed_buffers_num();
1251 if (curr_queue_size >= cg1r->yellow_zone()) {
1252 dcqs.set_completed_queue_padding(curr_queue_size);
1253 } else {
1254 dcqs.set_completed_queue_padding(0);
1255 }
1256 dcqs.notify_if_necessary();
1257 }
1258
1259 double
1260 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1261 size_t scanned_cards) {
1262 return
1263 predict_rs_update_time_ms(pending_cards) +
1264 predict_rs_scan_time_ms(scanned_cards) +
1265 predict_constant_other_time_ms();
1266 }
1267
1268 double
1269 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1270 size_t rs_length = predict_rs_length_diff();
1271 size_t card_num;
1272 if (gcs_are_young()) {
1273 card_num = predict_young_card_num(rs_length);
1274 } else {
1275 card_num = predict_non_young_card_num(rs_length);
1276 }
1277 return predict_base_elapsed_time_ms(pending_cards, card_num);
1278 }
1279
1280 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1281 size_t bytes_to_copy;
1282 if (hr->is_marked())
1283 bytes_to_copy = hr->max_live_bytes();
1284 else {
1285 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1286 int age = hr->age_in_surv_rate_group();
1287 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1288 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1289 }
1290 return bytes_to_copy;
1291 }
1292
1293 double
1294 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1295 bool for_young_gc) {
1296 size_t rs_length = hr->rem_set()->occupied();
1297 size_t card_num;
1298
1299 // Predicting the number of cards is based on which type of GC
1300 // we're predicting for.
1301 if (for_young_gc) {
1302 card_num = predict_young_card_num(rs_length);
1303 } else {
1304 card_num = predict_non_young_card_num(rs_length);
1305 }
1306 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1307
1308 double region_elapsed_time_ms =
1309 predict_rs_scan_time_ms(card_num) +
1310 predict_object_copy_time_ms(bytes_to_copy);
1311
1312 // The prediction of the "other" time for this region is based
1313 // upon the region type and NOT the GC type.
1314 if (hr->is_young()) {
1315 region_elapsed_time_ms += predict_young_other_time_ms(1);
1316 } else {
1317 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1318 }
1319 return region_elapsed_time_ms;
1320 }
1321
1322 void
1323 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1324 uint survivor_cset_region_length) {
1325 _eden_cset_region_length = eden_cset_region_length;
1326 _survivor_cset_region_length = survivor_cset_region_length;
1327 _old_cset_region_length = 0;
1328 }
1329
1330 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1331 _recorded_rs_lengths = rs_lengths;
1332 }
1333
1334 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1335 double elapsed_ms) {
1336 _recent_gc_times_ms->add(elapsed_ms);
1337 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1338 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1339 }
1340
1341 size_t G1CollectorPolicy::expansion_amount() {
1342 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1343 double threshold = _gc_overhead_perc;
1344 if (recent_gc_overhead > threshold) {
1345 // We will double the existing space, or take
1346 // G1ExpandByPercentOfAvailable % of the available expansion
1347 // space, whichever is smaller, bounded below by a minimum
1348 // expansion (unless that's all that's left.)
1349 const size_t min_expand_bytes = 1*M;
1350 size_t reserved_bytes = _g1->max_capacity();
1351 size_t committed_bytes = _g1->capacity();
1352 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1353 size_t expand_bytes;
1354 size_t expand_bytes_via_pct =
1355 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1356 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1357 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1358 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1359
1360 ergo_verbose5(ErgoHeapSizing,
1361 "attempt heap expansion",
1362 ergo_format_reason("recent GC overhead higher than "
1363 "threshold after GC")
1364 ergo_format_perc("recent GC overhead")
1365 ergo_format_perc("threshold")
1366 ergo_format_byte("uncommitted")
1367 ergo_format_byte_perc("calculated expansion amount"),
1368 recent_gc_overhead, threshold,
1369 uncommitted_bytes,
1370 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1371
1372 return expand_bytes;
1373 } else {
1374 return 0;
1375 }
1376 }
1377
1378 void G1CollectorPolicy::print_tracing_info() const {
1379 _trace_gen0_time_data.print();
1380 _trace_gen1_time_data.print();
1381 }
1382
1383 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1384 #ifndef PRODUCT
1385 _short_lived_surv_rate_group->print_surv_rate_summary();
1386 // add this call for any other surv rate groups
1387 #endif // PRODUCT
1388 }
1389
1390 uint G1CollectorPolicy::max_regions(int purpose) {
1391 switch (purpose) {
1392 case GCAllocForSurvived:
1393 return _max_survivor_regions;
1394 case GCAllocForTenured:
1395 return REGIONS_UNLIMITED;
1396 default:
1397 ShouldNotReachHere();
1398 return REGIONS_UNLIMITED;
1399 };
1400 }
1401
1402 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1403 uint expansion_region_num = 0;
1404 if (GCLockerEdenExpansionPercent > 0) {
1405 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1406 double expansion_region_num_d = perc * (double) _young_list_target_length;
1407 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1408 // less than 1.0) we'll get 1.
1409 expansion_region_num = (uint) ceil(expansion_region_num_d);
1410 } else {
1411 assert(expansion_region_num == 0, "sanity");
1412 }
1413 _young_list_max_length = _young_list_target_length + expansion_region_num;
1414 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1415 }
1416
1417 // Calculates survivor space parameters.
1418 void G1CollectorPolicy::update_survivors_policy() {
1419 double max_survivor_regions_d =
1420 (double) _young_list_target_length / (double) SurvivorRatio;
1421 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1422 // smaller than 1.0) we'll get 1.
1423 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1424
1425 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1426 HeapRegion::GrainWords * _max_survivor_regions);
1427 }
1428
1429 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1430 GCCause::Cause gc_cause) {
1431 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1432 if (!during_cycle) {
1433 ergo_verbose1(ErgoConcCycles,
1434 "request concurrent cycle initiation",
1435 ergo_format_reason("requested by GC cause")
1436 ergo_format_str("GC cause"),
1437 GCCause::to_string(gc_cause));
1438 set_initiate_conc_mark_if_possible();
1439 return true;
1440 } else {
1441 ergo_verbose1(ErgoConcCycles,
1442 "do not request concurrent cycle initiation",
1443 ergo_format_reason("concurrent cycle already in progress")
1444 ergo_format_str("GC cause"),
1445 GCCause::to_string(gc_cause));
1446 return false;
1447 }
1448 }
1449
1450 void
1451 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1452 // We are about to decide on whether this pause will be an
1453 // initial-mark pause.
1454
1455 // First, during_initial_mark_pause() should not be already set. We
1456 // will set it here if we have to. However, it should be cleared by
1457 // the end of the pause (it's only set for the duration of an
1458 // initial-mark pause).
1459 assert(!during_initial_mark_pause(), "pre-condition");
1460
1461 if (initiate_conc_mark_if_possible()) {
1462 // We had noticed on a previous pause that the heap occupancy has
1463 // gone over the initiating threshold and we should start a
1464 // concurrent marking cycle. So we might initiate one.
1465
1466 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1467 if (!during_cycle) {
1468 // The concurrent marking thread is not "during a cycle", i.e.,
1469 // it has completed the last one. So we can go ahead and
1470 // initiate a new cycle.
1471
1472 set_during_initial_mark_pause();
1473 // We do not allow mixed GCs during marking.
1474 if (!gcs_are_young()) {
1475 set_gcs_are_young(true);
1476 ergo_verbose0(ErgoMixedGCs,
1477 "end mixed GCs",
1478 ergo_format_reason("concurrent cycle is about to start"));
1479 }
1480
1481 // And we can now clear initiate_conc_mark_if_possible() as
1482 // we've already acted on it.
1483 clear_initiate_conc_mark_if_possible();
1484
1485 ergo_verbose0(ErgoConcCycles,
1486 "initiate concurrent cycle",
1487 ergo_format_reason("concurrent cycle initiation requested"));
1488 } else {
1489 // The concurrent marking thread is still finishing up the
1490 // previous cycle. If we start one right now the two cycles
1491 // overlap. In particular, the concurrent marking thread might
1492 // be in the process of clearing the next marking bitmap (which
1493 // we will use for the next cycle if we start one). Starting a
1494 // cycle now will be bad given that parts of the marking
1495 // information might get cleared by the marking thread. And we
1496 // cannot wait for the marking thread to finish the cycle as it
1497 // periodically yields while clearing the next marking bitmap
1498 // and, if it's in a yield point, it's waiting for us to
1499 // finish. So, at this point we will not start a cycle and we'll
1500 // let the concurrent marking thread complete the last one.
1501 ergo_verbose0(ErgoConcCycles,
1502 "do not initiate concurrent cycle",
1503 ergo_format_reason("concurrent cycle already in progress"));
1504 }
1505 }
1506 }
1507
1508 class KnownGarbageClosure: public HeapRegionClosure {
1509 G1CollectedHeap* _g1h;
1510 CollectionSetChooser* _hrSorted;
1511
1512 public:
1513 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1514 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1515
1516 bool doHeapRegion(HeapRegion* r) {
1517 // We only include humongous regions in collection
1518 // sets when concurrent mark shows that their contained object is
1519 // unreachable.
1520
1521 // Do we have any marking information for this region?
1522 if (r->is_marked()) {
1523 // We will skip any region that's currently used as an old GC
1524 // alloc region (we should not consider those for collection
1525 // before we fill them up).
1526 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1527 _hrSorted->add_region(r);
1528 }
1529 }
1530 return false;
1531 }
1532 };
1533
1534 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1535 G1CollectedHeap* _g1h;
1536 CSetChooserParUpdater _cset_updater;
1537
1538 public:
1539 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1540 uint chunk_size) :
1541 _g1h(G1CollectedHeap::heap()),
1542 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1543
1544 bool doHeapRegion(HeapRegion* r) {
1545 // Do we have any marking information for this region?
1546 if (r->is_marked()) {
1547 // We will skip any region that's currently used as an old GC
1548 // alloc region (we should not consider those for collection
1549 // before we fill them up).
1550 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1551 _cset_updater.add_region(r);
1552 }
1553 }
1554 return false;
1555 }
1556 };
1557
1558 class ParKnownGarbageTask: public AbstractGangTask {
1559 CollectionSetChooser* _hrSorted;
1560 uint _chunk_size;
1561 G1CollectedHeap* _g1;
1562 public:
1563 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1564 AbstractGangTask("ParKnownGarbageTask"),
1565 _hrSorted(hrSorted), _chunk_size(chunk_size),
1566 _g1(G1CollectedHeap::heap()) { }
1567
1568 void work(uint worker_id) {
1569 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1570
1571 // Back to zero for the claim value.
1572 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1573 _g1->workers()->active_workers(),
1574 HeapRegion::InitialClaimValue);
1575 }
1576 };
1577
1578 void
1579 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1580 _collectionSetChooser->clear();
1581
1582 uint region_num = _g1->n_regions();
1583 if (G1CollectedHeap::use_parallel_gc_threads()) {
1584 const uint OverpartitionFactor = 4;
1585 uint WorkUnit;
1586 // The use of MinChunkSize = 8 in the original code
1587 // causes some assertion failures when the total number of
1588 // region is less than 8. The code here tries to fix that.
1589 // Should the original code also be fixed?
1590 if (no_of_gc_threads > 0) {
1591 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1592 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1593 MinWorkUnit);
1594 } else {
1595 assert(no_of_gc_threads > 0,
1596 "The active gc workers should be greater than 0");
1597 // In a product build do something reasonable to avoid a crash.
1598 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1599 WorkUnit =
1600 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1601 MinWorkUnit);
1602 }
1603 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1604 WorkUnit);
1605 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1606 (int) WorkUnit);
1607 _g1->workers()->run_task(&parKnownGarbageTask);
1608
1609 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1610 "sanity check");
1611 } else {
1612 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1613 _g1->heap_region_iterate(&knownGarbagecl);
1614 }
1615
1616 _collectionSetChooser->sort_regions();
1617
1618 double end_sec = os::elapsedTime();
1619 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1620 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1621 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1622 _prev_collection_pause_end_ms += elapsed_time_ms;
1623 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1624 }
1625
1626 // Add the heap region at the head of the non-incremental collection set
1627 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1628 assert(_inc_cset_build_state == Active, "Precondition");
1629 assert(!hr->is_young(), "non-incremental add of young region");
1630
1631 assert(!hr->in_collection_set(), "should not already be in the CSet");
1632 hr->set_in_collection_set(true);
1633 hr->set_next_in_collection_set(_collection_set);
1634 _collection_set = hr;
1635 _collection_set_bytes_used_before += hr->used();
1636 _g1->register_region_with_in_cset_fast_test(hr);
1637 size_t rs_length = hr->rem_set()->occupied();
1638 _recorded_rs_lengths += rs_length;
1639 _old_cset_region_length += 1;
1640 }
1641
1642 // Initialize the per-collection-set information
1643 void G1CollectorPolicy::start_incremental_cset_building() {
1644 assert(_inc_cset_build_state == Inactive, "Precondition");
1645
1646 _inc_cset_head = NULL;
1647 _inc_cset_tail = NULL;
1648 _inc_cset_bytes_used_before = 0;
1649
1650 _inc_cset_max_finger = 0;
1651 _inc_cset_recorded_rs_lengths = 0;
1652 _inc_cset_recorded_rs_lengths_diffs = 0;
1653 _inc_cset_predicted_elapsed_time_ms = 0.0;
1654 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1655 _inc_cset_build_state = Active;
1656 }
1657
1658 void G1CollectorPolicy::finalize_incremental_cset_building() {
1659 assert(_inc_cset_build_state == Active, "Precondition");
1660 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1661
1662 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1663 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1664 // that adds a new region to the CSet. Further updates by the
1665 // concurrent refinement thread that samples the young RSet lengths
1666 // are accumulated in the *_diffs fields. Here we add the diffs to
1667 // the "main" fields.
1668
1669 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1670 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1671 } else {
1672 // This is defensive. The diff should in theory be always positive
1673 // as RSets can only grow between GCs. However, given that we
1674 // sample their size concurrently with other threads updating them
1675 // it's possible that we might get the wrong size back, which
1676 // could make the calculations somewhat inaccurate.
1677 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1678 if (_inc_cset_recorded_rs_lengths >= diffs) {
1679 _inc_cset_recorded_rs_lengths -= diffs;
1680 } else {
1681 _inc_cset_recorded_rs_lengths = 0;
1682 }
1683 }
1684 _inc_cset_predicted_elapsed_time_ms +=
1685 _inc_cset_predicted_elapsed_time_ms_diffs;
1686
1687 _inc_cset_recorded_rs_lengths_diffs = 0;
1688 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1689 }
1690
1691 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1692 // This routine is used when:
1693 // * adding survivor regions to the incremental cset at the end of an
1694 // evacuation pause,
1695 // * adding the current allocation region to the incremental cset
1696 // when it is retired, and
1697 // * updating existing policy information for a region in the
1698 // incremental cset via young list RSet sampling.
1699 // Therefore this routine may be called at a safepoint by the
1700 // VM thread, or in-between safepoints by mutator threads (when
1701 // retiring the current allocation region) or a concurrent
1702 // refine thread (RSet sampling).
1703
1704 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1705 size_t used_bytes = hr->used();
1706 _inc_cset_recorded_rs_lengths += rs_length;
1707 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1708 _inc_cset_bytes_used_before += used_bytes;
1709
1710 // Cache the values we have added to the aggregated informtion
1711 // in the heap region in case we have to remove this region from
1712 // the incremental collection set, or it is updated by the
1713 // rset sampling code
1714 hr->set_recorded_rs_length(rs_length);
1715 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1716 }
1717
1718 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1719 size_t new_rs_length) {
1720 // Update the CSet information that is dependent on the new RS length
1721 assert(hr->is_young(), "Precondition");
1722 assert(!SafepointSynchronize::is_at_safepoint(),
1723 "should not be at a safepoint");
1724
1725 // We could have updated _inc_cset_recorded_rs_lengths and
1726 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1727 // that atomically, as this code is executed by a concurrent
1728 // refinement thread, potentially concurrently with a mutator thread
1729 // allocating a new region and also updating the same fields. To
1730 // avoid the atomic operations we accumulate these updates on two
1731 // separate fields (*_diffs) and we'll just add them to the "main"
1732 // fields at the start of a GC.
1733
1734 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1735 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1736 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1737
1738 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1739 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1740 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1741 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1742
1743 hr->set_recorded_rs_length(new_rs_length);
1744 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1745 }
1746
1747 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1748 assert(hr->is_young(), "invariant");
1749 assert(hr->young_index_in_cset() > -1, "should have already been set");
1750 assert(_inc_cset_build_state == Active, "Precondition");
1751
1752 // We need to clear and set the cached recorded/cached collection set
1753 // information in the heap region here (before the region gets added
1754 // to the collection set). An individual heap region's cached values
1755 // are calculated, aggregated with the policy collection set info,
1756 // and cached in the heap region here (initially) and (subsequently)
1757 // by the Young List sampling code.
1758
1759 size_t rs_length = hr->rem_set()->occupied();
1760 add_to_incremental_cset_info(hr, rs_length);
1761
1762 HeapWord* hr_end = hr->end();
1763 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1764
1765 assert(!hr->in_collection_set(), "invariant");
1766 hr->set_in_collection_set(true);
1767 assert( hr->next_in_collection_set() == NULL, "invariant");
1768
1769 _g1->register_region_with_in_cset_fast_test(hr);
1770 }
1771
1772 // Add the region at the RHS of the incremental cset
1773 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1774 // We should only ever be appending survivors at the end of a pause
1775 assert( hr->is_survivor(), "Logic");
1776
1777 // Do the 'common' stuff
1778 add_region_to_incremental_cset_common(hr);
1779
1780 // Now add the region at the right hand side
1781 if (_inc_cset_tail == NULL) {
1782 assert(_inc_cset_head == NULL, "invariant");
1783 _inc_cset_head = hr;
1784 } else {
1785 _inc_cset_tail->set_next_in_collection_set(hr);
1786 }
1787 _inc_cset_tail = hr;
1788 }
1789
1790 // Add the region to the LHS of the incremental cset
1791 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1792 // Survivors should be added to the RHS at the end of a pause
1793 assert(!hr->is_survivor(), "Logic");
1794
1795 // Do the 'common' stuff
1796 add_region_to_incremental_cset_common(hr);
1797
1798 // Add the region at the left hand side
1799 hr->set_next_in_collection_set(_inc_cset_head);
1800 if (_inc_cset_head == NULL) {
1801 assert(_inc_cset_tail == NULL, "Invariant");
1802 _inc_cset_tail = hr;
1803 }
1804 _inc_cset_head = hr;
1805 }
1806
1807 #ifndef PRODUCT
1808 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1809 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1810
1811 st->print_cr("\nCollection_set:");
1812 HeapRegion* csr = list_head;
1813 while (csr != NULL) {
1814 HeapRegion* next = csr->next_in_collection_set();
1815 assert(csr->in_collection_set(), "bad CS");
1816 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1817 HR_FORMAT_PARAMS(csr),
1818 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1819 csr->age_in_surv_rate_group_cond());
1820 csr = next;
1821 }
1822 }
1823 #endif // !PRODUCT
1824
1825 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1826 // Returns the given amount of reclaimable bytes (that represents
1827 // the amount of reclaimable space still to be collected) as a
1828 // percentage of the current heap capacity.
1829 size_t capacity_bytes = _g1->capacity();
1830 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1831 }
1832
1833 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1834 const char* false_action_str) {
1835 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1836 if (cset_chooser->is_empty()) {
1837 ergo_verbose0(ErgoMixedGCs,
1838 false_action_str,
1839 ergo_format_reason("candidate old regions not available"));
1840 return false;
1841 }
1842
1843 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1844 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1845 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1846 double threshold = (double) G1HeapWastePercent;
1847 if (reclaimable_perc <= threshold) {
1848 ergo_verbose4(ErgoMixedGCs,
1849 false_action_str,
1850 ergo_format_reason("reclaimable percentage not over threshold")
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 false;
1858 }
1859
1860 ergo_verbose4(ErgoMixedGCs,
1861 true_action_str,
1862 ergo_format_reason("candidate old regions available")
1863 ergo_format_region("candidate old regions")
1864 ergo_format_byte_perc("reclaimable")
1865 ergo_format_perc("threshold"),
1866 cset_chooser->remaining_regions(),
1867 reclaimable_bytes,
1868 reclaimable_perc, threshold);
1869 return true;
1870 }
1871
1872 uint G1CollectorPolicy::calc_min_old_cset_length() {
1873 // The min old CSet region bound is based on the maximum desired
1874 // number of mixed GCs after a cycle. I.e., even if some old regions
1875 // look expensive, we should add them to the CSet anyway to make
1876 // sure we go through the available old regions in no more than the
1877 // maximum desired number of mixed GCs.
1878 //
1879 // The calculation is based on the number of marked regions we added
1880 // to the CSet chooser in the first place, not how many remain, so
1881 // that the result is the same during all mixed GCs that follow a cycle.
1882
1883 const size_t region_num = (size_t) _collectionSetChooser->length();
1884 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1885 size_t result = region_num / gc_num;
1886 // emulate ceiling
1887 if (result * gc_num < region_num) {
1888 result += 1;
1889 }
1890 return (uint) result;
1891 }
1892
1893 uint G1CollectorPolicy::calc_max_old_cset_length() {
1894 // The max old CSet region bound is based on the threshold expressed
1895 // as a percentage of the heap size. I.e., it should bound the
1896 // number of old regions added to the CSet irrespective of how many
1897 // of them are available.
1898
1899 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1900 const size_t region_num = g1h->n_regions();
1901 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1902 size_t result = region_num * perc / 100;
1903 // emulate ceiling
1904 if (100 * result < region_num * perc) {
1905 result += 1;
1906 }
1907 return (uint) result;
1908 }
1909
1910
1911 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1912 double young_start_time_sec = os::elapsedTime();
1913
1914 YoungList* young_list = _g1->young_list();
1915 finalize_incremental_cset_building();
1916
1917 guarantee(target_pause_time_ms > 0.0,
1918 err_msg("target_pause_time_ms = %1.6lf should be positive",
1919 target_pause_time_ms));
1920 guarantee(_collection_set == NULL, "Precondition");
1921
1922 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1923 double predicted_pause_time_ms = base_time_ms;
1924 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1925
1926 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1927 "start choosing CSet",
1928 ergo_format_size("_pending_cards")
1929 ergo_format_ms("predicted base time")
1930 ergo_format_ms("remaining time")
1931 ergo_format_ms("target pause time"),
1932 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1933
1934 _last_gc_was_young = gcs_are_young() ? true : false;
1935
1936 if (_last_gc_was_young) {
1937 _trace_gen0_time_data.increment_young_collection_count();
1938 } else {
1939 _trace_gen0_time_data.increment_mixed_collection_count();
1940 }
1941
1942 // The young list is laid with the survivor regions from the previous
1943 // pause are appended to the RHS of the young list, i.e.
1944 // [Newly Young Regions ++ Survivors from last pause].
1945
1946 uint survivor_region_length = young_list->survivor_length();
1947 uint eden_region_length = young_list->length() - survivor_region_length;
1948 init_cset_region_lengths(eden_region_length, survivor_region_length);
1949
1950 HeapRegion* hr = young_list->first_survivor_region();
1951 while (hr != NULL) {
1952 assert(hr->is_survivor(), "badly formed young list");
1953 hr->set_young();
1954 hr = hr->get_next_young_region();
1955 }
1956
1957 // Clear the fields that point to the survivor list - they are all young now.
1958 young_list->clear_survivors();
1959
1960 _collection_set = _inc_cset_head;
1961 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1962 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1963 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1964
1965 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1966 "add young regions to CSet",
1967 ergo_format_region("eden")
1968 ergo_format_region("survivors")
1969 ergo_format_ms("predicted young region time"),
1970 eden_region_length, survivor_region_length,
1971 _inc_cset_predicted_elapsed_time_ms);
1972
1973 // The number of recorded young regions is the incremental
1974 // collection set's current size
1975 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1976
1977 double young_end_time_sec = os::elapsedTime();
1978 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1979
1980 // Set the start of the non-young choice time.
1981 double non_young_start_time_sec = young_end_time_sec;
1982
1983 if (!gcs_are_young()) {
1984 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1985 cset_chooser->verify();
1986 const uint min_old_cset_length = calc_min_old_cset_length();
1987 const uint max_old_cset_length = calc_max_old_cset_length();
1988
1989 uint expensive_region_num = 0;
1990 bool check_time_remaining = adaptive_young_list_length();
1991
1992 HeapRegion* hr = cset_chooser->peek();
1993 while (hr != NULL) {
1994 if (old_cset_region_length() >= max_old_cset_length) {
1995 // Added maximum number of old regions to the CSet.
1996 ergo_verbose2(ErgoCSetConstruction,
1997 "finish adding old regions to CSet",
1998 ergo_format_reason("old CSet region num reached max")
1999 ergo_format_region("old")
2000 ergo_format_region("max"),
2001 old_cset_region_length(), max_old_cset_length);
2002 break;
2003 }
2004
2005
2006 // Stop adding regions if the remaining reclaimable space is
2007 // not above G1HeapWastePercent.
2008 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2009 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2010 double threshold = (double) G1HeapWastePercent;
2011 if (reclaimable_perc <= threshold) {
2012 // We've added enough old regions that the amount of uncollected
2013 // reclaimable space is at or below the waste threshold. Stop
2014 // adding old regions to the CSet.
2015 ergo_verbose5(ErgoCSetConstruction,
2016 "finish adding old regions to CSet",
2017 ergo_format_reason("reclaimable percentage not over threshold")
2018 ergo_format_region("old")
2019 ergo_format_region("max")
2020 ergo_format_byte_perc("reclaimable")
2021 ergo_format_perc("threshold"),
2022 old_cset_region_length(),
2023 max_old_cset_length,
2024 reclaimable_bytes,
2025 reclaimable_perc, threshold);
2026 break;
2027 }
2028
2029 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2030 if (check_time_remaining) {
2031 if (predicted_time_ms > time_remaining_ms) {
2032 // Too expensive for the current CSet.
2033
2034 if (old_cset_region_length() >= min_old_cset_length) {
2035 // We have added the minimum number of old regions to the CSet,
2036 // we are done with this CSet.
2037 ergo_verbose4(ErgoCSetConstruction,
2038 "finish adding old regions to CSet",
2039 ergo_format_reason("predicted time is too high")
2040 ergo_format_ms("predicted time")
2041 ergo_format_ms("remaining time")
2042 ergo_format_region("old")
2043 ergo_format_region("min"),
2044 predicted_time_ms, time_remaining_ms,
2045 old_cset_region_length(), min_old_cset_length);
2046 break;
2047 }
2048
2049 // We'll add it anyway given that we haven't reached the
2050 // minimum number of old regions.
2051 expensive_region_num += 1;
2052 }
2053 } else {
2054 if (old_cset_region_length() >= min_old_cset_length) {
2055 // In the non-auto-tuning case, we'll finish adding regions
2056 // to the CSet if we reach the minimum.
2057 ergo_verbose2(ErgoCSetConstruction,
2058 "finish adding old regions to CSet",
2059 ergo_format_reason("old CSet region num reached min")
2060 ergo_format_region("old")
2061 ergo_format_region("min"),
2062 old_cset_region_length(), min_old_cset_length);
2063 break;
2064 }
2065 }
2066
2067 // We will add this region to the CSet.
2068 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2069 predicted_pause_time_ms += predicted_time_ms;
2070 cset_chooser->remove_and_move_to_next(hr);
2071 _g1->old_set_remove(hr);
2072 add_old_region_to_cset(hr);
2073
2074 hr = cset_chooser->peek();
2075 }
2076 if (hr == NULL) {
2077 ergo_verbose0(ErgoCSetConstruction,
2078 "finish adding old regions to CSet",
2079 ergo_format_reason("candidate old regions not available"));
2080 }
2081
2082 if (expensive_region_num > 0) {
2083 // We print the information once here at the end, predicated on
2084 // whether we added any apparently expensive regions or not, to
2085 // avoid generating output per region.
2086 ergo_verbose4(ErgoCSetConstruction,
2087 "added expensive regions to CSet",
2088 ergo_format_reason("old CSet region num not reached min")
2089 ergo_format_region("old")
2090 ergo_format_region("expensive")
2091 ergo_format_region("min")
2092 ergo_format_ms("remaining time"),
2093 old_cset_region_length(),
2094 expensive_region_num,
2095 min_old_cset_length,
2096 time_remaining_ms);
2097 }
2098
2099 cset_chooser->verify();
2100 }
2101
2102 stop_incremental_cset_building();
2103
2104 ergo_verbose5(ErgoCSetConstruction,
2105 "finish choosing CSet",
2106 ergo_format_region("eden")
2107 ergo_format_region("survivors")
2108 ergo_format_region("old")
2109 ergo_format_ms("predicted pause time")
2110 ergo_format_ms("target pause time"),
2111 eden_region_length, survivor_region_length,
2112 old_cset_region_length(),
2113 predicted_pause_time_ms, target_pause_time_ms);
2114
2115 double non_young_end_time_sec = os::elapsedTime();
2116 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2117 evacuation_info.set_collectionset_regions(cset_region_length());
2118 }
2119
2120 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2121 if(TraceGen0Time) {
2122 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2123 }
2124 }
2125
2126 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2127 if(TraceGen0Time) {
2128 _all_yield_times_ms.add(yield_time_ms);
2129 }
2130 }
2131
2132 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2133 if(TraceGen0Time) {
2134 _total.add(pause_time_ms);
2135 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2136 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2137 _parallel.add(phase_times->cur_collection_par_time_ms());
2138 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2139 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2140 _update_rs.add(phase_times->average_last_update_rs_time());
2141 _scan_rs.add(phase_times->average_last_scan_rs_time());
2142 _obj_copy.add(phase_times->average_last_obj_copy_time());
2143 _termination.add(phase_times->average_last_termination_time());
2144
2145 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2146 phase_times->average_last_satb_filtering_times_ms() +
2147 phase_times->average_last_update_rs_time() +
2148 phase_times->average_last_scan_rs_time() +
2149 phase_times->average_last_obj_copy_time() +
2150 + phase_times->average_last_termination_time();
2151
2152 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2153 _parallel_other.add(parallel_other_time);
2154 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2155 }
2156 }
2157
2158 void TraceGen0TimeData::increment_young_collection_count() {
2159 if(TraceGen0Time) {
2160 ++_young_pause_num;
2161 }
2162 }
2163
2164 void TraceGen0TimeData::increment_mixed_collection_count() {
2165 if(TraceGen0Time) {
2166 ++_mixed_pause_num;
2167 }
2168 }
2169
2170 void TraceGen0TimeData::print_summary(const char* str,
2171 const NumberSeq* seq) const {
2172 double sum = seq->sum();
2173 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2174 str, sum / 1000.0, seq->avg());
2175 }
2176
2177 void TraceGen0TimeData::print_summary_sd(const char* str,
2178 const NumberSeq* seq) const {
2179 print_summary(str, seq);
2180 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2181 "(num", seq->num(), seq->sd(), seq->maximum());
2182 }
2183
2184 void TraceGen0TimeData::print() const {
2185 if (!TraceGen0Time) {
2186 return;
2187 }
2188
2189 gclog_or_tty->print_cr("ALL PAUSES");
2190 print_summary_sd(" Total", &_total);
2191 gclog_or_tty->print_cr("");
2192 gclog_or_tty->print_cr("");
2193 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2194 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2195 gclog_or_tty->print_cr("");
2196
2197 gclog_or_tty->print_cr("EVACUATION PAUSES");
2198
2199 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2200 gclog_or_tty->print_cr("none");
2201 } else {
2202 print_summary_sd(" Evacuation Pauses", &_total);
2203 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2204 print_summary(" Parallel Time", &_parallel);
2205 print_summary(" Ext Root Scanning", &_ext_root_scan);
2206 print_summary(" SATB Filtering", &_satb_filtering);
2207 print_summary(" Update RS", &_update_rs);
2208 print_summary(" Scan RS", &_scan_rs);
2209 print_summary(" Object Copy", &_obj_copy);
2210 print_summary(" Termination", &_termination);
2211 print_summary(" Parallel Other", &_parallel_other);
2212 print_summary(" Clear CT", &_clear_ct);
2213 print_summary(" Other", &_other);
2214 }
2215 gclog_or_tty->print_cr("");
2216
2217 gclog_or_tty->print_cr("MISC");
2218 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2219 print_summary_sd(" Yields", &_all_yield_times_ms);
2220 }
2221
2222 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2223 if (TraceGen1Time) {
2224 _all_full_gc_times.add(full_gc_time_ms);
2225 }
2226 }
2227
2228 void TraceGen1TimeData::print() const {
2229 if (!TraceGen1Time) {
2230 return;
2231 }
2232
2233 if (_all_full_gc_times.num() > 0) {
2234 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2235 _all_full_gc_times.num(),
2236 _all_full_gc_times.sum() / 1000.0);
2237 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2238 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2239 _all_full_gc_times.sd(),
2240 _all_full_gc_times.maximum());
2241 }
2242 }