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 set_min_alignment(HeapRegion::GrainBytes);
323 size_t card_table_alignment = GenRemSet::max_alignment_constraint(rem_set_name());
324 set_max_alignment(MAX2(card_table_alignment, min_alignment()));
325 if (SurvivorRatio < 1) {
326 vm_exit_during_initialization("Invalid survivor ratio specified");
327 }
328 CollectorPolicy::initialize_flags();
329 }
330
331 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
332 assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max");
333 assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds");
334 assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds");
335
336 if (FLAG_IS_CMDLINE(NewRatio)) {
337 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
338 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
339 } else {
340 _sizer_kind = SizerNewRatio;
341 _adaptive_size = false;
342 return;
343 }
344 }
345
346 if (FLAG_IS_CMDLINE(NewSize)) {
347 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
348 1U);
349 if (FLAG_IS_CMDLINE(MaxNewSize)) {
350 _max_desired_young_length =
351 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
352 1U);
353 _sizer_kind = SizerMaxAndNewSize;
354 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
355 } else {
356 _sizer_kind = SizerNewSizeOnly;
357 }
358 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
359 _max_desired_young_length =
360 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
361 1U);
362 _sizer_kind = SizerMaxNewSizeOnly;
363 }
364 }
365
366 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
367 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
368 return MAX2(1U, default_value);
369 }
370
371 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
372 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
373 return MAX2(1U, default_value);
374 }
375
376 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
377 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
378
379 switch (_sizer_kind) {
380 case SizerDefaults:
381 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
382 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
383 break;
384 case SizerNewSizeOnly:
385 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
386 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
387 break;
388 case SizerMaxNewSizeOnly:
389 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
390 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
391 break;
392 case SizerMaxAndNewSize:
393 // Do nothing. Values set on the command line, don't update them at runtime.
394 break;
395 case SizerNewRatio:
396 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
397 _max_desired_young_length = _min_desired_young_length;
398 break;
399 default:
400 ShouldNotReachHere();
401 }
402
403 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
404 }
405
406 void G1CollectorPolicy::init() {
407 // Set aside an initial future to_space.
408 _g1 = G1CollectedHeap::heap();
409
410 assert(Heap_lock->owned_by_self(), "Locking discipline.");
411
412 initialize_gc_policy_counters();
413
414 if (adaptive_young_list_length()) {
415 _young_list_fixed_length = 0;
416 } else {
417 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
418 }
419 _free_regions_at_end_of_collection = _g1->free_regions();
420 update_young_list_target_length();
421
422 // We may immediately start allocating regions and placing them on the
423 // collection set list. Initialize the per-collection set info
424 start_incremental_cset_building();
425 }
426
427 // Create the jstat counters for the policy.
428 void G1CollectorPolicy::initialize_gc_policy_counters() {
429 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
430 }
431
432 bool G1CollectorPolicy::predict_will_fit(uint young_length,
433 double base_time_ms,
434 uint base_free_regions,
435 double target_pause_time_ms) {
436 if (young_length >= base_free_regions) {
437 // end condition 1: not enough space for the young regions
438 return false;
439 }
440
441 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
442 size_t bytes_to_copy =
443 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
444 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
445 double young_other_time_ms = predict_young_other_time_ms(young_length);
446 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
447 if (pause_time_ms > target_pause_time_ms) {
448 // end condition 2: prediction is over the target pause time
449 return false;
450 }
451
452 size_t free_bytes =
453 (base_free_regions - young_length) * HeapRegion::GrainBytes;
454 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
455 // end condition 3: out-of-space (conservatively!)
456 return false;
457 }
458
459 // success!
460 return true;
461 }
462
463 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
464 // re-calculate the necessary reserve
465 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
466 // We use ceiling so that if reserve_regions_d is > 0.0 (but
467 // smaller than 1.0) we'll get 1.
468 _reserve_regions = (uint) ceil(reserve_regions_d);
469
470 _young_gen_sizer->heap_size_changed(new_number_of_regions);
471 }
472
473 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
474 uint base_min_length) {
475 uint desired_min_length = 0;
476 if (adaptive_young_list_length()) {
477 if (_alloc_rate_ms_seq->num() > 3) {
478 double now_sec = os::elapsedTime();
479 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
480 double alloc_rate_ms = predict_alloc_rate_ms();
481 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
482 } else {
483 // otherwise we don't have enough info to make the prediction
484 }
485 }
486 desired_min_length += base_min_length;
487 // make sure we don't go below any user-defined minimum bound
488 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
489 }
490
491 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
492 // Here, we might want to also take into account any additional
493 // constraints (i.e., user-defined minimum bound). Currently, we
494 // effectively don't set this bound.
495 return _young_gen_sizer->max_desired_young_length();
496 }
497
498 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
499 if (rs_lengths == (size_t) -1) {
500 // if it's set to the default value (-1), we should predict it;
501 // otherwise, use the given value.
502 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
503 }
504
505 // Calculate the absolute and desired min bounds.
506
507 // This is how many young regions we already have (currently: the survivors).
508 uint base_min_length = recorded_survivor_regions();
509 // This is the absolute minimum young length, which ensures that we
510 // can allocate one eden region in the worst-case.
511 uint absolute_min_length = base_min_length + 1;
512 uint desired_min_length =
513 calculate_young_list_desired_min_length(base_min_length);
514 if (desired_min_length < absolute_min_length) {
515 desired_min_length = absolute_min_length;
516 }
517
518 // Calculate the absolute and desired max bounds.
519
520 // We will try our best not to "eat" into the reserve.
521 uint absolute_max_length = 0;
522 if (_free_regions_at_end_of_collection > _reserve_regions) {
523 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
524 }
525 uint desired_max_length = calculate_young_list_desired_max_length();
526 if (desired_max_length > absolute_max_length) {
527 desired_max_length = absolute_max_length;
528 }
529
530 uint young_list_target_length = 0;
531 if (adaptive_young_list_length()) {
532 if (gcs_are_young()) {
533 young_list_target_length =
534 calculate_young_list_target_length(rs_lengths,
535 base_min_length,
536 desired_min_length,
537 desired_max_length);
538 _rs_lengths_prediction = rs_lengths;
539 } else {
540 // Don't calculate anything and let the code below bound it to
541 // the desired_min_length, i.e., do the next GC as soon as
542 // possible to maximize how many old regions we can add to it.
543 }
544 } else {
545 // The user asked for a fixed young gen so we'll fix the young gen
546 // whether the next GC is young or mixed.
547 young_list_target_length = _young_list_fixed_length;
548 }
549
550 // Make sure we don't go over the desired max length, nor under the
551 // desired min length. In case they clash, desired_min_length wins
552 // which is why that test is second.
553 if (young_list_target_length > desired_max_length) {
554 young_list_target_length = desired_max_length;
555 }
556 if (young_list_target_length < desired_min_length) {
557 young_list_target_length = desired_min_length;
558 }
559
560 assert(young_list_target_length > recorded_survivor_regions(),
561 "we should be able to allocate at least one eden region");
562 assert(young_list_target_length >= absolute_min_length, "post-condition");
563 _young_list_target_length = young_list_target_length;
564
565 update_max_gc_locker_expansion();
566 }
567
568 uint
569 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
570 uint base_min_length,
571 uint desired_min_length,
572 uint desired_max_length) {
573 assert(adaptive_young_list_length(), "pre-condition");
574 assert(gcs_are_young(), "only call this for young GCs");
575
576 // In case some edge-condition makes the desired max length too small...
577 if (desired_max_length <= desired_min_length) {
578 return desired_min_length;
579 }
580
581 // We'll adjust min_young_length and max_young_length not to include
582 // the already allocated young regions (i.e., so they reflect the
583 // min and max eden regions we'll allocate). The base_min_length
584 // will be reflected in the predictions by the
585 // survivor_regions_evac_time prediction.
586 assert(desired_min_length > base_min_length, "invariant");
587 uint min_young_length = desired_min_length - base_min_length;
588 assert(desired_max_length > base_min_length, "invariant");
589 uint max_young_length = desired_max_length - base_min_length;
590
591 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
592 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
593 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
594 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
595 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
596 double base_time_ms =
597 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
598 survivor_regions_evac_time;
599 uint available_free_regions = _free_regions_at_end_of_collection;
600 uint base_free_regions = 0;
601 if (available_free_regions > _reserve_regions) {
602 base_free_regions = available_free_regions - _reserve_regions;
603 }
604
605 // Here, we will make sure that the shortest young length that
606 // makes sense fits within the target pause time.
607
608 if (predict_will_fit(min_young_length, base_time_ms,
609 base_free_regions, target_pause_time_ms)) {
610 // The shortest young length will fit into the target pause time;
611 // we'll now check whether the absolute maximum number of young
612 // regions will fit in the target pause time. If not, we'll do
613 // a binary search between min_young_length and max_young_length.
614 if (predict_will_fit(max_young_length, base_time_ms,
615 base_free_regions, target_pause_time_ms)) {
616 // The maximum young length will fit into the target pause time.
617 // We are done so set min young length to the maximum length (as
618 // the result is assumed to be returned in min_young_length).
619 min_young_length = max_young_length;
620 } else {
621 // The maximum possible number of young regions will not fit within
622 // the target pause time so we'll search for the optimal
623 // length. The loop invariants are:
624 //
625 // min_young_length < max_young_length
626 // min_young_length is known to fit into the target pause time
627 // max_young_length is known not to fit into the target pause time
628 //
629 // Going into the loop we know the above hold as we've just
630 // checked them. Every time around the loop we check whether
631 // the middle value between min_young_length and
632 // max_young_length fits into the target pause time. If it
633 // does, it becomes the new min. If it doesn't, it becomes
634 // the new max. This way we maintain the loop invariants.
635
636 assert(min_young_length < max_young_length, "invariant");
637 uint diff = (max_young_length - min_young_length) / 2;
638 while (diff > 0) {
639 uint young_length = min_young_length + diff;
640 if (predict_will_fit(young_length, base_time_ms,
641 base_free_regions, target_pause_time_ms)) {
642 min_young_length = young_length;
643 } else {
644 max_young_length = young_length;
645 }
646 assert(min_young_length < max_young_length, "invariant");
647 diff = (max_young_length - min_young_length) / 2;
648 }
649 // The results is min_young_length which, according to the
650 // loop invariants, should fit within the target pause time.
651
652 // These are the post-conditions of the binary search above:
653 assert(min_young_length < max_young_length,
654 "otherwise we should have discovered that max_young_length "
655 "fits into the pause target and not done the binary search");
656 assert(predict_will_fit(min_young_length, base_time_ms,
657 base_free_regions, target_pause_time_ms),
658 "min_young_length, the result of the binary search, should "
659 "fit into the pause target");
660 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
661 base_free_regions, target_pause_time_ms),
662 "min_young_length, the result of the binary search, should be "
663 "optimal, so no larger length should fit into the pause target");
664 }
665 } else {
666 // Even the minimum length doesn't fit into the pause time
667 // target, return it as the result nevertheless.
668 }
669 return base_min_length + min_young_length;
670 }
671
672 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
673 double survivor_regions_evac_time = 0.0;
674 for (HeapRegion * r = _recorded_survivor_head;
675 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
676 r = r->get_next_young_region()) {
677 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
678 }
679 return survivor_regions_evac_time;
680 }
681
682 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
683 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
684
685 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
686 if (rs_lengths > _rs_lengths_prediction) {
687 // add 10% to avoid having to recalculate often
688 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
689 update_young_list_target_length(rs_lengths_prediction);
690 }
691 }
692
693
694
695 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
696 bool is_tlab,
697 bool* gc_overhead_limit_was_exceeded) {
698 guarantee(false, "Not using this policy feature yet.");
699 return NULL;
700 }
701
702 // This method controls how a collector handles one or more
703 // of its generations being fully allocated.
704 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
705 bool is_tlab) {
706 guarantee(false, "Not using this policy feature yet.");
707 return NULL;
708 }
709
710
711 #ifndef PRODUCT
712 bool G1CollectorPolicy::verify_young_ages() {
713 HeapRegion* head = _g1->young_list()->first_region();
714 return
715 verify_young_ages(head, _short_lived_surv_rate_group);
716 // also call verify_young_ages on any additional surv rate groups
717 }
718
719 bool
720 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
721 SurvRateGroup *surv_rate_group) {
722 guarantee( surv_rate_group != NULL, "pre-condition" );
723
724 const char* name = surv_rate_group->name();
725 bool ret = true;
726 int prev_age = -1;
727
728 for (HeapRegion* curr = head;
729 curr != NULL;
730 curr = curr->get_next_young_region()) {
731 SurvRateGroup* group = curr->surv_rate_group();
732 if (group == NULL && !curr->is_survivor()) {
733 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
734 ret = false;
735 }
736
737 if (surv_rate_group == group) {
738 int age = curr->age_in_surv_rate_group();
739
740 if (age < 0) {
741 gclog_or_tty->print_cr("## %s: encountered negative age", name);
742 ret = false;
743 }
744
745 if (age <= prev_age) {
746 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
747 "(%d, %d)", name, age, prev_age);
748 ret = false;
749 }
750 prev_age = age;
751 }
752 }
753
754 return ret;
755 }
756 #endif // PRODUCT
757
758 void G1CollectorPolicy::record_full_collection_start() {
759 _full_collection_start_sec = os::elapsedTime();
760 record_heap_size_info_at_start(true /* full */);
761 // Release the future to-space so that it is available for compaction into.
762 _g1->set_full_collection();
763 }
764
765 void G1CollectorPolicy::record_full_collection_end() {
766 // Consider this like a collection pause for the purposes of allocation
767 // since last pause.
768 double end_sec = os::elapsedTime();
769 double full_gc_time_sec = end_sec - _full_collection_start_sec;
770 double full_gc_time_ms = full_gc_time_sec * 1000.0;
771
772 _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
773
774 update_recent_gc_times(end_sec, full_gc_time_ms);
775
776 _g1->clear_full_collection();
777
778 // "Nuke" the heuristics that control the young/mixed GC
779 // transitions and make sure we start with young GCs after the Full GC.
780 set_gcs_are_young(true);
781 _last_young_gc = false;
782 clear_initiate_conc_mark_if_possible();
783 clear_during_initial_mark_pause();
784 _in_marking_window = false;
785 _in_marking_window_im = false;
786
787 _short_lived_surv_rate_group->start_adding_regions();
788 // also call this on any additional surv rate groups
789
790 record_survivor_regions(0, NULL, NULL);
791
792 _free_regions_at_end_of_collection = _g1->free_regions();
793 // Reset survivors SurvRateGroup.
794 _survivor_surv_rate_group->reset();
795 update_young_list_target_length();
796 _collectionSetChooser->clear();
797 }
798
799 void G1CollectorPolicy::record_stop_world_start() {
800 _stop_world_start = os::elapsedTime();
801 }
802
803 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
804 // We only need to do this here as the policy will only be applied
805 // to the GC we're about to start. so, no point is calculating this
806 // every time we calculate / recalculate the target young length.
807 update_survivors_policy();
808
809 assert(_g1->used() == _g1->recalculate_used(),
810 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
811 _g1->used(), _g1->recalculate_used()));
812
813 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
814 _trace_gen0_time_data.record_start_collection(s_w_t_ms);
815 _stop_world_start = 0.0;
816
817 record_heap_size_info_at_start(false /* full */);
818
819 phase_times()->record_cur_collection_start_sec(start_time_sec);
820 _pending_cards = _g1->pending_card_num();
821
822 _collection_set_bytes_used_before = 0;
823 _bytes_copied_during_gc = 0;
824
825 _last_gc_was_young = false;
826
827 // do that for any other surv rate groups
828 _short_lived_surv_rate_group->stop_adding_regions();
829 _survivors_age_table.clear();
830
831 assert( verify_young_ages(), "region age verification" );
832 }
833
834 void G1CollectorPolicy::record_concurrent_mark_init_end(double
835 mark_init_elapsed_time_ms) {
836 _during_marking = true;
837 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
838 clear_during_initial_mark_pause();
839 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
840 }
841
842 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
843 _mark_remark_start_sec = os::elapsedTime();
844 _during_marking = false;
845 }
846
847 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
848 double end_time_sec = os::elapsedTime();
849 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
850 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
851 _cur_mark_stop_world_time_ms += elapsed_time_ms;
852 _prev_collection_pause_end_ms += elapsed_time_ms;
853
854 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
855 }
856
857 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
858 _mark_cleanup_start_sec = os::elapsedTime();
859 }
860
861 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
862 _last_young_gc = true;
863 _in_marking_window = false;
864 }
865
866 void G1CollectorPolicy::record_concurrent_pause() {
867 if (_stop_world_start > 0.0) {
868 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
869 _trace_gen0_time_data.record_yield_time(yield_ms);
870 }
871 }
872
873 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
874 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
875 return false;
876 }
877
878 size_t marking_initiating_used_threshold =
879 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
880 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
881 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
882
883 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
884 if (gcs_are_young() && !_last_young_gc) {
885 ergo_verbose5(ErgoConcCycles,
886 "request concurrent cycle initiation",
887 ergo_format_reason("occupancy higher than threshold")
888 ergo_format_byte("occupancy")
889 ergo_format_byte("allocation request")
890 ergo_format_byte_perc("threshold")
891 ergo_format_str("source"),
892 cur_used_bytes,
893 alloc_byte_size,
894 marking_initiating_used_threshold,
895 (double) InitiatingHeapOccupancyPercent,
896 source);
897 return true;
898 } else {
899 ergo_verbose5(ErgoConcCycles,
900 "do not request concurrent cycle initiation",
901 ergo_format_reason("still doing mixed collections")
902 ergo_format_byte("occupancy")
903 ergo_format_byte("allocation request")
904 ergo_format_byte_perc("threshold")
905 ergo_format_str("source"),
906 cur_used_bytes,
907 alloc_byte_size,
908 marking_initiating_used_threshold,
909 (double) InitiatingHeapOccupancyPercent,
910 source);
911 }
912 }
913
914 return false;
915 }
916
917 // Anything below that is considered to be zero
918 #define MIN_TIMER_GRANULARITY 0.0000001
919
920 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
921 double end_time_sec = os::elapsedTime();
922 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
923 "otherwise, the subtraction below does not make sense");
924 size_t rs_size =
925 _cur_collection_pause_used_regions_at_start - cset_region_length();
926 size_t cur_used_bytes = _g1->used();
927 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
928 bool last_pause_included_initial_mark = false;
929 bool update_stats = !_g1->evacuation_failed();
930
931 #ifndef PRODUCT
932 if (G1YoungSurvRateVerbose) {
933 gclog_or_tty->print_cr("");
934 _short_lived_surv_rate_group->print();
935 // do that for any other surv rate groups too
936 }
937 #endif // PRODUCT
938
939 last_pause_included_initial_mark = during_initial_mark_pause();
940 if (last_pause_included_initial_mark) {
941 record_concurrent_mark_init_end(0.0);
942 } else if (need_to_start_conc_mark("end of GC")) {
943 // Note: this might have already been set, if during the last
944 // pause we decided to start a cycle but at the beginning of
945 // this pause we decided to postpone it. That's OK.
946 set_initiate_conc_mark_if_possible();
947 }
948
949 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
950 end_time_sec, false);
951
952 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
953 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
954
955 if (update_stats) {
956 _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
957 // this is where we update the allocation rate of the application
958 double app_time_ms =
959 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
960 if (app_time_ms < MIN_TIMER_GRANULARITY) {
961 // This usually happens due to the timer not having the required
962 // granularity. Some Linuxes are the usual culprits.
963 // We'll just set it to something (arbitrarily) small.
964 app_time_ms = 1.0;
965 }
966 // We maintain the invariant that all objects allocated by mutator
967 // threads will be allocated out of eden regions. So, we can use
968 // the eden region number allocated since the previous GC to
969 // calculate the application's allocate rate. The only exception
970 // to that is humongous objects that are allocated separately. But
971 // given that humongous object allocations do not really affect
972 // either the pause's duration nor when the next pause will take
973 // place we can safely ignore them here.
974 uint regions_allocated = eden_cset_region_length();
975 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
976 _alloc_rate_ms_seq->add(alloc_rate_ms);
977
978 double interval_ms =
979 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
980 update_recent_gc_times(end_time_sec, pause_time_ms);
981 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
982 if (recent_avg_pause_time_ratio() < 0.0 ||
983 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
984 #ifndef PRODUCT
985 // Dump info to allow post-facto debugging
986 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
987 gclog_or_tty->print_cr("-------------------------------------------");
988 gclog_or_tty->print_cr("Recent GC Times (ms):");
989 _recent_gc_times_ms->dump();
990 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
991 _recent_prev_end_times_for_all_gcs_sec->dump();
992 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
993 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
994 // In debug mode, terminate the JVM if the user wants to debug at this point.
995 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
996 #endif // !PRODUCT
997 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
998 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
999 if (_recent_avg_pause_time_ratio < 0.0) {
1000 _recent_avg_pause_time_ratio = 0.0;
1001 } else {
1002 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1003 _recent_avg_pause_time_ratio = 1.0;
1004 }
1005 }
1006 }
1007
1008 bool new_in_marking_window = _in_marking_window;
1009 bool new_in_marking_window_im = false;
1010 if (during_initial_mark_pause()) {
1011 new_in_marking_window = true;
1012 new_in_marking_window_im = true;
1013 }
1014
1015 if (_last_young_gc) {
1016 // This is supposed to to be the "last young GC" before we start
1017 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1018
1019 if (!last_pause_included_initial_mark) {
1020 if (next_gc_should_be_mixed("start mixed GCs",
1021 "do not start mixed GCs")) {
1022 set_gcs_are_young(false);
1023 }
1024 } else {
1025 ergo_verbose0(ErgoMixedGCs,
1026 "do not start mixed GCs",
1027 ergo_format_reason("concurrent cycle is about to start"));
1028 }
1029 _last_young_gc = false;
1030 }
1031
1032 if (!_last_gc_was_young) {
1033 // This is a mixed GC. Here we decide whether to continue doing
1034 // mixed GCs or not.
1035
1036 if (!next_gc_should_be_mixed("continue mixed GCs",
1037 "do not continue mixed GCs")) {
1038 set_gcs_are_young(true);
1039 }
1040 }
1041
1042 _short_lived_surv_rate_group->start_adding_regions();
1043 // do that for any other surv rate groupsx
1044
1045 if (update_stats) {
1046 double cost_per_card_ms = 0.0;
1047 if (_pending_cards > 0) {
1048 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1049 _cost_per_card_ms_seq->add(cost_per_card_ms);
1050 }
1051
1052 size_t cards_scanned = _g1->cards_scanned();
1053
1054 double cost_per_entry_ms = 0.0;
1055 if (cards_scanned > 10) {
1056 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1057 if (_last_gc_was_young) {
1058 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1059 } else {
1060 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1061 }
1062 }
1063
1064 if (_max_rs_lengths > 0) {
1065 double cards_per_entry_ratio =
1066 (double) cards_scanned / (double) _max_rs_lengths;
1067 if (_last_gc_was_young) {
1068 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1069 } else {
1070 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1071 }
1072 }
1073
1074 // This is defensive. For a while _max_rs_lengths could get
1075 // smaller than _recorded_rs_lengths which was causing
1076 // rs_length_diff to get very large and mess up the RSet length
1077 // predictions. The reason was unsafe concurrent updates to the
1078 // _inc_cset_recorded_rs_lengths field which the code below guards
1079 // against (see CR 7118202). This bug has now been fixed (see CR
1080 // 7119027). However, I'm still worried that
1081 // _inc_cset_recorded_rs_lengths might still end up somewhat
1082 // inaccurate. The concurrent refinement thread calculates an
1083 // RSet's length concurrently with other CR threads updating it
1084 // which might cause it to calculate the length incorrectly (if,
1085 // say, it's in mid-coarsening). So I'll leave in the defensive
1086 // conditional below just in case.
1087 size_t rs_length_diff = 0;
1088 if (_max_rs_lengths > _recorded_rs_lengths) {
1089 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1090 }
1091 _rs_length_diff_seq->add((double) rs_length_diff);
1092
1093 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1094 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1095 double cost_per_byte_ms = 0.0;
1096
1097 if (copied_bytes > 0) {
1098 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1099 if (_in_marking_window) {
1100 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1101 } else {
1102 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1103 }
1104 }
1105
1106 double all_other_time_ms = pause_time_ms -
1107 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1108 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1109
1110 double young_other_time_ms = 0.0;
1111 if (young_cset_region_length() > 0) {
1112 young_other_time_ms =
1113 phase_times()->young_cset_choice_time_ms() +
1114 phase_times()->young_free_cset_time_ms();
1115 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1116 (double) young_cset_region_length());
1117 }
1118 double non_young_other_time_ms = 0.0;
1119 if (old_cset_region_length() > 0) {
1120 non_young_other_time_ms =
1121 phase_times()->non_young_cset_choice_time_ms() +
1122 phase_times()->non_young_free_cset_time_ms();
1123
1124 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1125 (double) old_cset_region_length());
1126 }
1127
1128 double constant_other_time_ms = all_other_time_ms -
1129 (young_other_time_ms + non_young_other_time_ms);
1130 _constant_other_time_ms_seq->add(constant_other_time_ms);
1131
1132 double survival_ratio = 0.0;
1133 if (_collection_set_bytes_used_before > 0) {
1134 survival_ratio = (double) _bytes_copied_during_gc /
1135 (double) _collection_set_bytes_used_before;
1136 }
1137
1138 _pending_cards_seq->add((double) _pending_cards);
1139 _rs_lengths_seq->add((double) _max_rs_lengths);
1140 }
1141
1142 _in_marking_window = new_in_marking_window;
1143 _in_marking_window_im = new_in_marking_window_im;
1144 _free_regions_at_end_of_collection = _g1->free_regions();
1145 update_young_list_target_length();
1146
1147 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1148 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1149 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1150 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1151
1152 _collectionSetChooser->verify();
1153 }
1154
1155 #define EXT_SIZE_FORMAT "%.1f%s"
1156 #define EXT_SIZE_PARAMS(bytes) \
1157 byte_size_in_proper_unit((double)(bytes)), \
1158 proper_unit_for_byte_size((bytes))
1159
1160 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1161 YoungList* young_list = _g1->young_list();
1162 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1163 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1164 _heap_capacity_bytes_before_gc = _g1->capacity();
1165 _heap_used_bytes_before_gc = _g1->used();
1166 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
1167
1168 _eden_capacity_bytes_before_gc =
1169 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1170
1171 if (full) {
1172 _metaspace_used_bytes_before_gc = MetaspaceAux::allocated_used_bytes();
1173 }
1174 }
1175
1176 void G1CollectorPolicy::print_heap_transition() {
1177 _g1->print_size_transition(gclog_or_tty,
1178 _heap_used_bytes_before_gc,
1179 _g1->used(),
1180 _g1->capacity());
1181 }
1182
1183 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {
1184 YoungList* young_list = _g1->young_list();
1185
1186 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1187 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1188 size_t heap_used_bytes_after_gc = _g1->used();
1189
1190 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1191 size_t eden_capacity_bytes_after_gc =
1192 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1193
1194 gclog_or_tty->print(
1195 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1196 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1197 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1198 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1199 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1200 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1201 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1202 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1203 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1204 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1205 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1206 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1207 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1208 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1209
1210 if (full) {
1211 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1212 }
1213
1214 gclog_or_tty->cr();
1215 }
1216
1217 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1218 double update_rs_processed_buffers,
1219 double goal_ms) {
1220 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1221 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1222
1223 if (G1UseAdaptiveConcRefinement) {
1224 const int k_gy = 3, k_gr = 6;
1225 const double inc_k = 1.1, dec_k = 0.9;
1226
1227 int g = cg1r->green_zone();
1228 if (update_rs_time > goal_ms) {
1229 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1230 } else {
1231 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1232 g = (int)MAX2(g * inc_k, g + 1.0);
1233 }
1234 }
1235 // Change the refinement threads params
1236 cg1r->set_green_zone(g);
1237 cg1r->set_yellow_zone(g * k_gy);
1238 cg1r->set_red_zone(g * k_gr);
1239 cg1r->reinitialize_threads();
1240
1241 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1242 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1243 cg1r->yellow_zone());
1244 // Change the barrier params
1245 dcqs.set_process_completed_threshold(processing_threshold);
1246 dcqs.set_max_completed_queue(cg1r->red_zone());
1247 }
1248
1249 int curr_queue_size = dcqs.completed_buffers_num();
1250 if (curr_queue_size >= cg1r->yellow_zone()) {
1251 dcqs.set_completed_queue_padding(curr_queue_size);
1252 } else {
1253 dcqs.set_completed_queue_padding(0);
1254 }
1255 dcqs.notify_if_necessary();
1256 }
1257
1258 double
1259 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1260 size_t scanned_cards) {
1261 return
1262 predict_rs_update_time_ms(pending_cards) +
1263 predict_rs_scan_time_ms(scanned_cards) +
1264 predict_constant_other_time_ms();
1265 }
1266
1267 double
1268 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1269 size_t rs_length = predict_rs_length_diff();
1270 size_t card_num;
1271 if (gcs_are_young()) {
1272 card_num = predict_young_card_num(rs_length);
1273 } else {
1274 card_num = predict_non_young_card_num(rs_length);
1275 }
1276 return predict_base_elapsed_time_ms(pending_cards, card_num);
1277 }
1278
1279 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1280 size_t bytes_to_copy;
1281 if (hr->is_marked())
1282 bytes_to_copy = hr->max_live_bytes();
1283 else {
1284 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1285 int age = hr->age_in_surv_rate_group();
1286 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1287 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1288 }
1289 return bytes_to_copy;
1290 }
1291
1292 double
1293 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1294 bool for_young_gc) {
1295 size_t rs_length = hr->rem_set()->occupied();
1296 size_t card_num;
1297
1298 // Predicting the number of cards is based on which type of GC
1299 // we're predicting for.
1300 if (for_young_gc) {
1301 card_num = predict_young_card_num(rs_length);
1302 } else {
1303 card_num = predict_non_young_card_num(rs_length);
1304 }
1305 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1306
1307 double region_elapsed_time_ms =
1308 predict_rs_scan_time_ms(card_num) +
1309 predict_object_copy_time_ms(bytes_to_copy);
1310
1311 // The prediction of the "other" time for this region is based
1312 // upon the region type and NOT the GC type.
1313 if (hr->is_young()) {
1314 region_elapsed_time_ms += predict_young_other_time_ms(1);
1315 } else {
1316 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1317 }
1318 return region_elapsed_time_ms;
1319 }
1320
1321 void
1322 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1323 uint survivor_cset_region_length) {
1324 _eden_cset_region_length = eden_cset_region_length;
1325 _survivor_cset_region_length = survivor_cset_region_length;
1326 _old_cset_region_length = 0;
1327 }
1328
1329 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1330 _recorded_rs_lengths = rs_lengths;
1331 }
1332
1333 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1334 double elapsed_ms) {
1335 _recent_gc_times_ms->add(elapsed_ms);
1336 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1337 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1338 }
1339
1340 size_t G1CollectorPolicy::expansion_amount() {
1341 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1342 double threshold = _gc_overhead_perc;
1343 if (recent_gc_overhead > threshold) {
1344 // We will double the existing space, or take
1345 // G1ExpandByPercentOfAvailable % of the available expansion
1346 // space, whichever is smaller, bounded below by a minimum
1347 // expansion (unless that's all that's left.)
1348 const size_t min_expand_bytes = 1*M;
1349 size_t reserved_bytes = _g1->max_capacity();
1350 size_t committed_bytes = _g1->capacity();
1351 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1352 size_t expand_bytes;
1353 size_t expand_bytes_via_pct =
1354 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1355 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1356 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1357 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1358
1359 ergo_verbose5(ErgoHeapSizing,
1360 "attempt heap expansion",
1361 ergo_format_reason("recent GC overhead higher than "
1362 "threshold after GC")
1363 ergo_format_perc("recent GC overhead")
1364 ergo_format_perc("threshold")
1365 ergo_format_byte("uncommitted")
1366 ergo_format_byte_perc("calculated expansion amount"),
1367 recent_gc_overhead, threshold,
1368 uncommitted_bytes,
1369 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1370
1371 return expand_bytes;
1372 } else {
1373 return 0;
1374 }
1375 }
1376
1377 void G1CollectorPolicy::print_tracing_info() const {
1378 _trace_gen0_time_data.print();
1379 _trace_gen1_time_data.print();
1380 }
1381
1382 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1383 #ifndef PRODUCT
1384 _short_lived_surv_rate_group->print_surv_rate_summary();
1385 // add this call for any other surv rate groups
1386 #endif // PRODUCT
1387 }
1388
1389 uint G1CollectorPolicy::max_regions(int purpose) {
1390 switch (purpose) {
1391 case GCAllocForSurvived:
1392 return _max_survivor_regions;
1393 case GCAllocForTenured:
1394 return REGIONS_UNLIMITED;
1395 default:
1396 ShouldNotReachHere();
1397 return REGIONS_UNLIMITED;
1398 };
1399 }
1400
1401 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1402 uint expansion_region_num = 0;
1403 if (GCLockerEdenExpansionPercent > 0) {
1404 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1405 double expansion_region_num_d = perc * (double) _young_list_target_length;
1406 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1407 // less than 1.0) we'll get 1.
1408 expansion_region_num = (uint) ceil(expansion_region_num_d);
1409 } else {
1410 assert(expansion_region_num == 0, "sanity");
1411 }
1412 _young_list_max_length = _young_list_target_length + expansion_region_num;
1413 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1414 }
1415
1416 // Calculates survivor space parameters.
1417 void G1CollectorPolicy::update_survivors_policy() {
1418 double max_survivor_regions_d =
1419 (double) _young_list_target_length / (double) SurvivorRatio;
1420 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1421 // smaller than 1.0) we'll get 1.
1422 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1423
1424 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1425 HeapRegion::GrainWords * _max_survivor_regions);
1426 }
1427
1428 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1429 GCCause::Cause gc_cause) {
1430 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1431 if (!during_cycle) {
1432 ergo_verbose1(ErgoConcCycles,
1433 "request concurrent cycle initiation",
1434 ergo_format_reason("requested by GC cause")
1435 ergo_format_str("GC cause"),
1436 GCCause::to_string(gc_cause));
1437 set_initiate_conc_mark_if_possible();
1438 return true;
1439 } else {
1440 ergo_verbose1(ErgoConcCycles,
1441 "do not request concurrent cycle initiation",
1442 ergo_format_reason("concurrent cycle already in progress")
1443 ergo_format_str("GC cause"),
1444 GCCause::to_string(gc_cause));
1445 return false;
1446 }
1447 }
1448
1449 void
1450 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1451 // We are about to decide on whether this pause will be an
1452 // initial-mark pause.
1453
1454 // First, during_initial_mark_pause() should not be already set. We
1455 // will set it here if we have to. However, it should be cleared by
1456 // the end of the pause (it's only set for the duration of an
1457 // initial-mark pause).
1458 assert(!during_initial_mark_pause(), "pre-condition");
1459
1460 if (initiate_conc_mark_if_possible()) {
1461 // We had noticed on a previous pause that the heap occupancy has
1462 // gone over the initiating threshold and we should start a
1463 // concurrent marking cycle. So we might initiate one.
1464
1465 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1466 if (!during_cycle) {
1467 // The concurrent marking thread is not "during a cycle", i.e.,
1468 // it has completed the last one. So we can go ahead and
1469 // initiate a new cycle.
1470
1471 set_during_initial_mark_pause();
1472 // We do not allow mixed GCs during marking.
1473 if (!gcs_are_young()) {
1474 set_gcs_are_young(true);
1475 ergo_verbose0(ErgoMixedGCs,
1476 "end mixed GCs",
1477 ergo_format_reason("concurrent cycle is about to start"));
1478 }
1479
1480 // And we can now clear initiate_conc_mark_if_possible() as
1481 // we've already acted on it.
1482 clear_initiate_conc_mark_if_possible();
1483
1484 ergo_verbose0(ErgoConcCycles,
1485 "initiate concurrent cycle",
1486 ergo_format_reason("concurrent cycle initiation requested"));
1487 } else {
1488 // The concurrent marking thread is still finishing up the
1489 // previous cycle. If we start one right now the two cycles
1490 // overlap. In particular, the concurrent marking thread might
1491 // be in the process of clearing the next marking bitmap (which
1492 // we will use for the next cycle if we start one). Starting a
1493 // cycle now will be bad given that parts of the marking
1494 // information might get cleared by the marking thread. And we
1495 // cannot wait for the marking thread to finish the cycle as it
1496 // periodically yields while clearing the next marking bitmap
1497 // and, if it's in a yield point, it's waiting for us to
1498 // finish. So, at this point we will not start a cycle and we'll
1499 // let the concurrent marking thread complete the last one.
1500 ergo_verbose0(ErgoConcCycles,
1501 "do not initiate concurrent cycle",
1502 ergo_format_reason("concurrent cycle already in progress"));
1503 }
1504 }
1505 }
1506
1507 class KnownGarbageClosure: public HeapRegionClosure {
1508 G1CollectedHeap* _g1h;
1509 CollectionSetChooser* _hrSorted;
1510
1511 public:
1512 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1513 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1514
1515 bool doHeapRegion(HeapRegion* r) {
1516 // We only include humongous regions in collection
1517 // sets when concurrent mark shows that their contained object is
1518 // unreachable.
1519
1520 // Do we have any marking information for this region?
1521 if (r->is_marked()) {
1522 // We will skip any region that's currently used as an old GC
1523 // alloc region (we should not consider those for collection
1524 // before we fill them up).
1525 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1526 _hrSorted->add_region(r);
1527 }
1528 }
1529 return false;
1530 }
1531 };
1532
1533 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1534 G1CollectedHeap* _g1h;
1535 CSetChooserParUpdater _cset_updater;
1536
1537 public:
1538 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1539 uint chunk_size) :
1540 _g1h(G1CollectedHeap::heap()),
1541 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1542
1543 bool doHeapRegion(HeapRegion* r) {
1544 // Do we have any marking information for this region?
1545 if (r->is_marked()) {
1546 // We will skip any region that's currently used as an old GC
1547 // alloc region (we should not consider those for collection
1548 // before we fill them up).
1549 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1550 _cset_updater.add_region(r);
1551 }
1552 }
1553 return false;
1554 }
1555 };
1556
1557 class ParKnownGarbageTask: public AbstractGangTask {
1558 CollectionSetChooser* _hrSorted;
1559 uint _chunk_size;
1560 G1CollectedHeap* _g1;
1561 public:
1562 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1563 AbstractGangTask("ParKnownGarbageTask"),
1564 _hrSorted(hrSorted), _chunk_size(chunk_size),
1565 _g1(G1CollectedHeap::heap()) { }
1566
1567 void work(uint worker_id) {
1568 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1569
1570 // Back to zero for the claim value.
1571 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1572 _g1->workers()->active_workers(),
1573 HeapRegion::InitialClaimValue);
1574 }
1575 };
1576
1577 void
1578 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1579 _collectionSetChooser->clear();
1580
1581 uint region_num = _g1->n_regions();
1582 if (G1CollectedHeap::use_parallel_gc_threads()) {
1583 const uint OverpartitionFactor = 4;
1584 uint WorkUnit;
1585 // The use of MinChunkSize = 8 in the original code
1586 // causes some assertion failures when the total number of
1587 // region is less than 8. The code here tries to fix that.
1588 // Should the original code also be fixed?
1589 if (no_of_gc_threads > 0) {
1590 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1591 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1592 MinWorkUnit);
1593 } else {
1594 assert(no_of_gc_threads > 0,
1595 "The active gc workers should be greater than 0");
1596 // In a product build do something reasonable to avoid a crash.
1597 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1598 WorkUnit =
1599 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1600 MinWorkUnit);
1601 }
1602 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1603 WorkUnit);
1604 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1605 (int) WorkUnit);
1606 _g1->workers()->run_task(&parKnownGarbageTask);
1607
1608 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1609 "sanity check");
1610 } else {
1611 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1612 _g1->heap_region_iterate(&knownGarbagecl);
1613 }
1614
1615 _collectionSetChooser->sort_regions();
1616
1617 double end_sec = os::elapsedTime();
1618 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1619 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1620 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1621 _prev_collection_pause_end_ms += elapsed_time_ms;
1622 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1623 }
1624
1625 // Add the heap region at the head of the non-incremental collection set
1626 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1627 assert(_inc_cset_build_state == Active, "Precondition");
1628 assert(!hr->is_young(), "non-incremental add of young region");
1629
1630 assert(!hr->in_collection_set(), "should not already be in the CSet");
1631 hr->set_in_collection_set(true);
1632 hr->set_next_in_collection_set(_collection_set);
1633 _collection_set = hr;
1634 _collection_set_bytes_used_before += hr->used();
1635 _g1->register_region_with_in_cset_fast_test(hr);
1636 size_t rs_length = hr->rem_set()->occupied();
1637 _recorded_rs_lengths += rs_length;
1638 _old_cset_region_length += 1;
1639 }
1640
1641 // Initialize the per-collection-set information
1642 void G1CollectorPolicy::start_incremental_cset_building() {
1643 assert(_inc_cset_build_state == Inactive, "Precondition");
1644
1645 _inc_cset_head = NULL;
1646 _inc_cset_tail = NULL;
1647 _inc_cset_bytes_used_before = 0;
1648
1649 _inc_cset_max_finger = 0;
1650 _inc_cset_recorded_rs_lengths = 0;
1651 _inc_cset_recorded_rs_lengths_diffs = 0;
1652 _inc_cset_predicted_elapsed_time_ms = 0.0;
1653 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1654 _inc_cset_build_state = Active;
1655 }
1656
1657 void G1CollectorPolicy::finalize_incremental_cset_building() {
1658 assert(_inc_cset_build_state == Active, "Precondition");
1659 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1660
1661 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1662 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1663 // that adds a new region to the CSet. Further updates by the
1664 // concurrent refinement thread that samples the young RSet lengths
1665 // are accumulated in the *_diffs fields. Here we add the diffs to
1666 // the "main" fields.
1667
1668 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1669 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1670 } else {
1671 // This is defensive. The diff should in theory be always positive
1672 // as RSets can only grow between GCs. However, given that we
1673 // sample their size concurrently with other threads updating them
1674 // it's possible that we might get the wrong size back, which
1675 // could make the calculations somewhat inaccurate.
1676 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1677 if (_inc_cset_recorded_rs_lengths >= diffs) {
1678 _inc_cset_recorded_rs_lengths -= diffs;
1679 } else {
1680 _inc_cset_recorded_rs_lengths = 0;
1681 }
1682 }
1683 _inc_cset_predicted_elapsed_time_ms +=
1684 _inc_cset_predicted_elapsed_time_ms_diffs;
1685
1686 _inc_cset_recorded_rs_lengths_diffs = 0;
1687 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1688 }
1689
1690 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1691 // This routine is used when:
1692 // * adding survivor regions to the incremental cset at the end of an
1693 // evacuation pause,
1694 // * adding the current allocation region to the incremental cset
1695 // when it is retired, and
1696 // * updating existing policy information for a region in the
1697 // incremental cset via young list RSet sampling.
1698 // Therefore this routine may be called at a safepoint by the
1699 // VM thread, or in-between safepoints by mutator threads (when
1700 // retiring the current allocation region) or a concurrent
1701 // refine thread (RSet sampling).
1702
1703 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1704 size_t used_bytes = hr->used();
1705 _inc_cset_recorded_rs_lengths += rs_length;
1706 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1707 _inc_cset_bytes_used_before += used_bytes;
1708
1709 // Cache the values we have added to the aggregated informtion
1710 // in the heap region in case we have to remove this region from
1711 // the incremental collection set, or it is updated by the
1712 // rset sampling code
1713 hr->set_recorded_rs_length(rs_length);
1714 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1715 }
1716
1717 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1718 size_t new_rs_length) {
1719 // Update the CSet information that is dependent on the new RS length
1720 assert(hr->is_young(), "Precondition");
1721 assert(!SafepointSynchronize::is_at_safepoint(),
1722 "should not be at a safepoint");
1723
1724 // We could have updated _inc_cset_recorded_rs_lengths and
1725 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1726 // that atomically, as this code is executed by a concurrent
1727 // refinement thread, potentially concurrently with a mutator thread
1728 // allocating a new region and also updating the same fields. To
1729 // avoid the atomic operations we accumulate these updates on two
1730 // separate fields (*_diffs) and we'll just add them to the "main"
1731 // fields at the start of a GC.
1732
1733 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1734 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1735 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1736
1737 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1738 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1739 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1740 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1741
1742 hr->set_recorded_rs_length(new_rs_length);
1743 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1744 }
1745
1746 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1747 assert(hr->is_young(), "invariant");
1748 assert(hr->young_index_in_cset() > -1, "should have already been set");
1749 assert(_inc_cset_build_state == Active, "Precondition");
1750
1751 // We need to clear and set the cached recorded/cached collection set
1752 // information in the heap region here (before the region gets added
1753 // to the collection set). An individual heap region's cached values
1754 // are calculated, aggregated with the policy collection set info,
1755 // and cached in the heap region here (initially) and (subsequently)
1756 // by the Young List sampling code.
1757
1758 size_t rs_length = hr->rem_set()->occupied();
1759 add_to_incremental_cset_info(hr, rs_length);
1760
1761 HeapWord* hr_end = hr->end();
1762 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1763
1764 assert(!hr->in_collection_set(), "invariant");
1765 hr->set_in_collection_set(true);
1766 assert( hr->next_in_collection_set() == NULL, "invariant");
1767
1768 _g1->register_region_with_in_cset_fast_test(hr);
1769 }
1770
1771 // Add the region at the RHS of the incremental cset
1772 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1773 // We should only ever be appending survivors at the end of a pause
1774 assert( hr->is_survivor(), "Logic");
1775
1776 // Do the 'common' stuff
1777 add_region_to_incremental_cset_common(hr);
1778
1779 // Now add the region at the right hand side
1780 if (_inc_cset_tail == NULL) {
1781 assert(_inc_cset_head == NULL, "invariant");
1782 _inc_cset_head = hr;
1783 } else {
1784 _inc_cset_tail->set_next_in_collection_set(hr);
1785 }
1786 _inc_cset_tail = hr;
1787 }
1788
1789 // Add the region to the LHS of the incremental cset
1790 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1791 // Survivors should be added to the RHS at the end of a pause
1792 assert(!hr->is_survivor(), "Logic");
1793
1794 // Do the 'common' stuff
1795 add_region_to_incremental_cset_common(hr);
1796
1797 // Add the region at the left hand side
1798 hr->set_next_in_collection_set(_inc_cset_head);
1799 if (_inc_cset_head == NULL) {
1800 assert(_inc_cset_tail == NULL, "Invariant");
1801 _inc_cset_tail = hr;
1802 }
1803 _inc_cset_head = hr;
1804 }
1805
1806 #ifndef PRODUCT
1807 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1808 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1809
1810 st->print_cr("\nCollection_set:");
1811 HeapRegion* csr = list_head;
1812 while (csr != NULL) {
1813 HeapRegion* next = csr->next_in_collection_set();
1814 assert(csr->in_collection_set(), "bad CS");
1815 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1816 HR_FORMAT_PARAMS(csr),
1817 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1818 csr->age_in_surv_rate_group_cond());
1819 csr = next;
1820 }
1821 }
1822 #endif // !PRODUCT
1823
1824 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1825 // Returns the given amount of reclaimable bytes (that represents
1826 // the amount of reclaimable space still to be collected) as a
1827 // percentage of the current heap capacity.
1828 size_t capacity_bytes = _g1->capacity();
1829 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1830 }
1831
1832 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1833 const char* false_action_str) {
1834 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1835 if (cset_chooser->is_empty()) {
1836 ergo_verbose0(ErgoMixedGCs,
1837 false_action_str,
1838 ergo_format_reason("candidate old regions not available"));
1839 return false;
1840 }
1841
1842 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1843 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1844 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1845 double threshold = (double) G1HeapWastePercent;
1846 if (reclaimable_perc <= threshold) {
1847 ergo_verbose4(ErgoMixedGCs,
1848 false_action_str,
1849 ergo_format_reason("reclaimable percentage not over threshold")
1850 ergo_format_region("candidate old regions")
1851 ergo_format_byte_perc("reclaimable")
1852 ergo_format_perc("threshold"),
1853 cset_chooser->remaining_regions(),
1854 reclaimable_bytes,
1855 reclaimable_perc, threshold);
1856 return false;
1857 }
1858
1859 ergo_verbose4(ErgoMixedGCs,
1860 true_action_str,
1861 ergo_format_reason("candidate old regions available")
1862 ergo_format_region("candidate old regions")
1863 ergo_format_byte_perc("reclaimable")
1864 ergo_format_perc("threshold"),
1865 cset_chooser->remaining_regions(),
1866 reclaimable_bytes,
1867 reclaimable_perc, threshold);
1868 return true;
1869 }
1870
1871 uint G1CollectorPolicy::calc_min_old_cset_length() {
1872 // The min old CSet region bound is based on the maximum desired
1873 // number of mixed GCs after a cycle. I.e., even if some old regions
1874 // look expensive, we should add them to the CSet anyway to make
1875 // sure we go through the available old regions in no more than the
1876 // maximum desired number of mixed GCs.
1877 //
1878 // The calculation is based on the number of marked regions we added
1879 // to the CSet chooser in the first place, not how many remain, so
1880 // that the result is the same during all mixed GCs that follow a cycle.
1881
1882 const size_t region_num = (size_t) _collectionSetChooser->length();
1883 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1884 size_t result = region_num / gc_num;
1885 // emulate ceiling
1886 if (result * gc_num < region_num) {
1887 result += 1;
1888 }
1889 return (uint) result;
1890 }
1891
1892 uint G1CollectorPolicy::calc_max_old_cset_length() {
1893 // The max old CSet region bound is based on the threshold expressed
1894 // as a percentage of the heap size. I.e., it should bound the
1895 // number of old regions added to the CSet irrespective of how many
1896 // of them are available.
1897
1898 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1899 const size_t region_num = g1h->n_regions();
1900 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1901 size_t result = region_num * perc / 100;
1902 // emulate ceiling
1903 if (100 * result < region_num * perc) {
1904 result += 1;
1905 }
1906 return (uint) result;
1907 }
1908
1909
1910 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1911 double young_start_time_sec = os::elapsedTime();
1912
1913 YoungList* young_list = _g1->young_list();
1914 finalize_incremental_cset_building();
1915
1916 guarantee(target_pause_time_ms > 0.0,
1917 err_msg("target_pause_time_ms = %1.6lf should be positive",
1918 target_pause_time_ms));
1919 guarantee(_collection_set == NULL, "Precondition");
1920
1921 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1922 double predicted_pause_time_ms = base_time_ms;
1923 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1924
1925 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1926 "start choosing CSet",
1927 ergo_format_size("_pending_cards")
1928 ergo_format_ms("predicted base time")
1929 ergo_format_ms("remaining time")
1930 ergo_format_ms("target pause time"),
1931 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1932
1933 _last_gc_was_young = gcs_are_young() ? true : false;
1934
1935 if (_last_gc_was_young) {
1936 _trace_gen0_time_data.increment_young_collection_count();
1937 } else {
1938 _trace_gen0_time_data.increment_mixed_collection_count();
1939 }
1940
1941 // The young list is laid with the survivor regions from the previous
1942 // pause are appended to the RHS of the young list, i.e.
1943 // [Newly Young Regions ++ Survivors from last pause].
1944
1945 uint survivor_region_length = young_list->survivor_length();
1946 uint eden_region_length = young_list->length() - survivor_region_length;
1947 init_cset_region_lengths(eden_region_length, survivor_region_length);
1948
1949 HeapRegion* hr = young_list->first_survivor_region();
1950 while (hr != NULL) {
1951 assert(hr->is_survivor(), "badly formed young list");
1952 hr->set_young();
1953 hr = hr->get_next_young_region();
1954 }
1955
1956 // Clear the fields that point to the survivor list - they are all young now.
1957 young_list->clear_survivors();
1958
1959 _collection_set = _inc_cset_head;
1960 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1961 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1962 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1963
1964 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1965 "add young regions to CSet",
1966 ergo_format_region("eden")
1967 ergo_format_region("survivors")
1968 ergo_format_ms("predicted young region time"),
1969 eden_region_length, survivor_region_length,
1970 _inc_cset_predicted_elapsed_time_ms);
1971
1972 // The number of recorded young regions is the incremental
1973 // collection set's current size
1974 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1975
1976 double young_end_time_sec = os::elapsedTime();
1977 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1978
1979 // Set the start of the non-young choice time.
1980 double non_young_start_time_sec = young_end_time_sec;
1981
1982 if (!gcs_are_young()) {
1983 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1984 cset_chooser->verify();
1985 const uint min_old_cset_length = calc_min_old_cset_length();
1986 const uint max_old_cset_length = calc_max_old_cset_length();
1987
1988 uint expensive_region_num = 0;
1989 bool check_time_remaining = adaptive_young_list_length();
1990
1991 HeapRegion* hr = cset_chooser->peek();
1992 while (hr != NULL) {
1993 if (old_cset_region_length() >= max_old_cset_length) {
1994 // Added maximum number of old regions to the CSet.
1995 ergo_verbose2(ErgoCSetConstruction,
1996 "finish adding old regions to CSet",
1997 ergo_format_reason("old CSet region num reached max")
1998 ergo_format_region("old")
1999 ergo_format_region("max"),
2000 old_cset_region_length(), max_old_cset_length);
2001 break;
2002 }
2003
2004
2005 // Stop adding regions if the remaining reclaimable space is
2006 // not above G1HeapWastePercent.
2007 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2008 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2009 double threshold = (double) G1HeapWastePercent;
2010 if (reclaimable_perc <= threshold) {
2011 // We've added enough old regions that the amount of uncollected
2012 // reclaimable space is at or below the waste threshold. Stop
2013 // adding old regions to the CSet.
2014 ergo_verbose5(ErgoCSetConstruction,
2015 "finish adding old regions to CSet",
2016 ergo_format_reason("reclaimable percentage not over threshold")
2017 ergo_format_region("old")
2018 ergo_format_region("max")
2019 ergo_format_byte_perc("reclaimable")
2020 ergo_format_perc("threshold"),
2021 old_cset_region_length(),
2022 max_old_cset_length,
2023 reclaimable_bytes,
2024 reclaimable_perc, threshold);
2025 break;
2026 }
2027
2028 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2029 if (check_time_remaining) {
2030 if (predicted_time_ms > time_remaining_ms) {
2031 // Too expensive for the current CSet.
2032
2033 if (old_cset_region_length() >= min_old_cset_length) {
2034 // We have added the minimum number of old regions to the CSet,
2035 // we are done with this CSet.
2036 ergo_verbose4(ErgoCSetConstruction,
2037 "finish adding old regions to CSet",
2038 ergo_format_reason("predicted time is too high")
2039 ergo_format_ms("predicted time")
2040 ergo_format_ms("remaining time")
2041 ergo_format_region("old")
2042 ergo_format_region("min"),
2043 predicted_time_ms, time_remaining_ms,
2044 old_cset_region_length(), min_old_cset_length);
2045 break;
2046 }
2047
2048 // We'll add it anyway given that we haven't reached the
2049 // minimum number of old regions.
2050 expensive_region_num += 1;
2051 }
2052 } else {
2053 if (old_cset_region_length() >= min_old_cset_length) {
2054 // In the non-auto-tuning case, we'll finish adding regions
2055 // to the CSet if we reach the minimum.
2056 ergo_verbose2(ErgoCSetConstruction,
2057 "finish adding old regions to CSet",
2058 ergo_format_reason("old CSet region num reached min")
2059 ergo_format_region("old")
2060 ergo_format_region("min"),
2061 old_cset_region_length(), min_old_cset_length);
2062 break;
2063 }
2064 }
2065
2066 // We will add this region to the CSet.
2067 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2068 predicted_pause_time_ms += predicted_time_ms;
2069 cset_chooser->remove_and_move_to_next(hr);
2070 _g1->old_set_remove(hr);
2071 add_old_region_to_cset(hr);
2072
2073 hr = cset_chooser->peek();
2074 }
2075 if (hr == NULL) {
2076 ergo_verbose0(ErgoCSetConstruction,
2077 "finish adding old regions to CSet",
2078 ergo_format_reason("candidate old regions not available"));
2079 }
2080
2081 if (expensive_region_num > 0) {
2082 // We print the information once here at the end, predicated on
2083 // whether we added any apparently expensive regions or not, to
2084 // avoid generating output per region.
2085 ergo_verbose4(ErgoCSetConstruction,
2086 "added expensive regions to CSet",
2087 ergo_format_reason("old CSet region num not reached min")
2088 ergo_format_region("old")
2089 ergo_format_region("expensive")
2090 ergo_format_region("min")
2091 ergo_format_ms("remaining time"),
2092 old_cset_region_length(),
2093 expensive_region_num,
2094 min_old_cset_length,
2095 time_remaining_ms);
2096 }
2097
2098 cset_chooser->verify();
2099 }
2100
2101 stop_incremental_cset_building();
2102
2103 ergo_verbose5(ErgoCSetConstruction,
2104 "finish choosing CSet",
2105 ergo_format_region("eden")
2106 ergo_format_region("survivors")
2107 ergo_format_region("old")
2108 ergo_format_ms("predicted pause time")
2109 ergo_format_ms("target pause time"),
2110 eden_region_length, survivor_region_length,
2111 old_cset_region_length(),
2112 predicted_pause_time_ms, target_pause_time_ms);
2113
2114 double non_young_end_time_sec = os::elapsedTime();
2115 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2116 evacuation_info.set_collectionset_regions(cset_region_length());
2117 }
2118
2119 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2120 if(TraceGen0Time) {
2121 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2122 }
2123 }
2124
2125 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2126 if(TraceGen0Time) {
2127 _all_yield_times_ms.add(yield_time_ms);
2128 }
2129 }
2130
2131 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2132 if(TraceGen0Time) {
2133 _total.add(pause_time_ms);
2134 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2135 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2136 _parallel.add(phase_times->cur_collection_par_time_ms());
2137 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2138 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2139 _update_rs.add(phase_times->average_last_update_rs_time());
2140 _scan_rs.add(phase_times->average_last_scan_rs_time());
2141 _obj_copy.add(phase_times->average_last_obj_copy_time());
2142 _termination.add(phase_times->average_last_termination_time());
2143
2144 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2145 phase_times->average_last_satb_filtering_times_ms() +
2146 phase_times->average_last_update_rs_time() +
2147 phase_times->average_last_scan_rs_time() +
2148 phase_times->average_last_obj_copy_time() +
2149 + phase_times->average_last_termination_time();
2150
2151 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2152 _parallel_other.add(parallel_other_time);
2153 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2154 }
2155 }
2156
2157 void TraceGen0TimeData::increment_young_collection_count() {
2158 if(TraceGen0Time) {
2159 ++_young_pause_num;
2160 }
2161 }
2162
2163 void TraceGen0TimeData::increment_mixed_collection_count() {
2164 if(TraceGen0Time) {
2165 ++_mixed_pause_num;
2166 }
2167 }
2168
2169 void TraceGen0TimeData::print_summary(const char* str,
2170 const NumberSeq* seq) const {
2171 double sum = seq->sum();
2172 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2173 str, sum / 1000.0, seq->avg());
2174 }
2175
2176 void TraceGen0TimeData::print_summary_sd(const char* str,
2177 const NumberSeq* seq) const {
2178 print_summary(str, seq);
2179 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2180 "(num", seq->num(), seq->sd(), seq->maximum());
2181 }
2182
2183 void TraceGen0TimeData::print() const {
2184 if (!TraceGen0Time) {
2185 return;
2186 }
2187
2188 gclog_or_tty->print_cr("ALL PAUSES");
2189 print_summary_sd(" Total", &_total);
2190 gclog_or_tty->print_cr("");
2191 gclog_or_tty->print_cr("");
2192 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2193 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2194 gclog_or_tty->print_cr("");
2195
2196 gclog_or_tty->print_cr("EVACUATION PAUSES");
2197
2198 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2199 gclog_or_tty->print_cr("none");
2200 } else {
2201 print_summary_sd(" Evacuation Pauses", &_total);
2202 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2203 print_summary(" Parallel Time", &_parallel);
2204 print_summary(" Ext Root Scanning", &_ext_root_scan);
2205 print_summary(" SATB Filtering", &_satb_filtering);
2206 print_summary(" Update RS", &_update_rs);
2207 print_summary(" Scan RS", &_scan_rs);
2208 print_summary(" Object Copy", &_obj_copy);
2209 print_summary(" Termination", &_termination);
2210 print_summary(" Parallel Other", &_parallel_other);
2211 print_summary(" Clear CT", &_clear_ct);
2212 print_summary(" Other", &_other);
2213 }
2214 gclog_or_tty->print_cr("");
2215
2216 gclog_or_tty->print_cr("MISC");
2217 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2218 print_summary_sd(" Yields", &_all_yield_times_ms);
2219 }
2220
2221 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2222 if (TraceGen1Time) {
2223 _all_full_gc_times.add(full_gc_time_ms);
2224 }
2225 }
2226
2227 void TraceGen1TimeData::print() const {
2228 if (!TraceGen1Time) {
2229 return;
2230 }
2231
2232 if (_all_full_gc_times.num() > 0) {
2233 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2234 _all_full_gc_times.num(),
2235 _all_full_gc_times.sum() / 1000.0);
2236 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2237 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2238 _all_full_gc_times.sd(),
2239 _all_full_gc_times.maximum());
2240 }
2241 }