1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef __clang_major__
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "gc_implementation/g1/concurrentG1Refine.hpp"
32 #include "gc_implementation/g1/concurrentMark.hpp"
33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
34 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
35 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
36 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/heapRegionRemSet.hpp"
40 #include "gc_implementation/shared/gcPolicyCounters.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/java.hpp"
43 #include "runtime/mutexLocker.hpp"
44 #include "utilities/debug.hpp"
45
46 // Different defaults for different number of GC threads
47 // They were chosen by running GCOld and SPECjbb on debris with different
48 // numbers of GC threads and choosing them based on the results
49
50 // all the same
51 static double rs_length_diff_defaults[] = {
52 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
53 };
54
55 static double cost_per_card_ms_defaults[] = {
56 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
57 };
58
59 // all the same
60 static double young_cards_per_entry_ratio_defaults[] = {
61 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
62 };
63
64 static double cost_per_entry_ms_defaults[] = {
65 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
66 };
67
68 static double cost_per_byte_ms_defaults[] = {
69 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
70 };
71
72 // these should be pretty consistent
73 static double constant_other_time_ms_defaults[] = {
74 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
75 };
76
77
78 static double young_other_cost_per_region_ms_defaults[] = {
79 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
80 };
81
82 static double non_young_other_cost_per_region_ms_defaults[] = {
83 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
84 };
85
86 G1CollectorPolicy::G1CollectorPolicy() :
87 _parallel_gc_threads(ParallelGCThreads),
88
89 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
90 _stop_world_start(0.0),
91
92 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
93 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
94
95 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
96 _prev_collection_pause_end_ms(0.0),
97 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
98 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
99 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
100 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
101 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
102 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
103 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
104 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
105 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
106 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
107 _non_young_other_cost_per_region_ms_seq(
108 new TruncatedSeq(TruncatedSeqLength)),
109
110 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
111 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
112
113 _pause_time_target_ms((double) MaxGCPauseMillis),
114
115 _gcs_are_young(true),
116
117 _during_marking(false),
118 _in_marking_window(false),
119 _in_marking_window_im(false),
120
121 _recent_prev_end_times_for_all_gcs_sec(
122 new TruncatedSeq(NumPrevPausesForHeuristics)),
123
124 _recent_avg_pause_time_ratio(0.0),
125
126 _initiate_conc_mark_if_possible(false),
127 _during_initial_mark_pause(false),
128 _last_young_gc(false),
129 _last_gc_was_young(false),
130
131 _eden_used_bytes_before_gc(0),
132 _survivor_used_bytes_before_gc(0),
133 _heap_used_bytes_before_gc(0),
134 _metaspace_used_bytes_before_gc(0),
135 _eden_capacity_bytes_before_gc(0),
136 _heap_capacity_bytes_before_gc(0),
137
138 _eden_cset_region_length(0),
139 _survivor_cset_region_length(0),
140 _old_cset_region_length(0),
141
142 _collection_set(NULL),
143 _collection_set_bytes_used_before(0),
144
145 // Incremental CSet attributes
146 _inc_cset_build_state(Inactive),
147 _inc_cset_head(NULL),
148 _inc_cset_tail(NULL),
149 _inc_cset_bytes_used_before(0),
150 _inc_cset_max_finger(NULL),
151 _inc_cset_recorded_rs_lengths(0),
152 _inc_cset_recorded_rs_lengths_diffs(0),
153 _inc_cset_predicted_elapsed_time_ms(0.0),
154 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
155
156 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
157 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
158 #endif // _MSC_VER
159
160 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
161 G1YoungSurvRateNumRegionsSummary)),
162 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
163 G1YoungSurvRateNumRegionsSummary)),
164 // add here any more surv rate groups
165 _recorded_survivor_regions(0),
166 _recorded_survivor_head(NULL),
167 _recorded_survivor_tail(NULL),
168 _survivors_age_table(true),
169
170 _gc_overhead_perc(0.0) {
171
172 // Set up the region size and associated fields. Given that the
173 // policy is created before the heap, we have to set this up here,
174 // so it's done as soon as possible.
175
176 // It would have been natural to pass initial_heap_byte_size() and
177 // max_heap_byte_size() to setup_heap_region_size() but those have
178 // not been set up at this point since they should be aligned with
179 // the region size. So, there is a circular dependency here. We base
180 // the region size on the heap size, but the heap size should be
181 // aligned with the region size. To get around this we use the
182 // unaligned values for the heap.
183 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
184 HeapRegionRemSet::setup_remset_size();
185
186 G1ErgoVerbose::initialize();
187 if (PrintAdaptiveSizePolicy) {
188 // Currently, we only use a single switch for all the heuristics.
189 G1ErgoVerbose::set_enabled(true);
190 // Given that we don't currently have a verboseness level
191 // parameter, we'll hardcode this to high. This can be easily
192 // changed in the future.
193 G1ErgoVerbose::set_level(ErgoHigh);
194 } else {
195 G1ErgoVerbose::set_enabled(false);
196 }
197
198 // Verify PLAB sizes
199 const size_t region_size = HeapRegion::GrainWords;
200 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
201 char buffer[128];
202 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
203 OldPLABSize > region_size ? "Old" : "Young", region_size);
204 vm_exit_during_initialization(buffer);
205 }
206
207 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
208 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
209
210 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
211
212 int index = MIN2(_parallel_gc_threads - 1, 7);
213
214 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
215 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
216 _young_cards_per_entry_ratio_seq->add(
217 young_cards_per_entry_ratio_defaults[index]);
218 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
219 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
220 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
221 _young_other_cost_per_region_ms_seq->add(
222 young_other_cost_per_region_ms_defaults[index]);
223 _non_young_other_cost_per_region_ms_seq->add(
224 non_young_other_cost_per_region_ms_defaults[index]);
225
226 // Below, we might need to calculate the pause time target based on
227 // the pause interval. When we do so we are going to give G1 maximum
228 // flexibility and allow it to do pauses when it needs to. So, we'll
229 // arrange that the pause interval to be pause time target + 1 to
230 // ensure that a) the pause time target is maximized with respect to
231 // the pause interval and b) we maintain the invariant that pause
232 // time target < pause interval. If the user does not want this
233 // maximum flexibility, they will have to set the pause interval
234 // explicitly.
235
236 // First make sure that, if either parameter is set, its value is
237 // reasonable.
238 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
239 if (MaxGCPauseMillis < 1) {
240 vm_exit_during_initialization("MaxGCPauseMillis should be "
241 "greater than 0");
242 }
243 }
244 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
245 if (GCPauseIntervalMillis < 1) {
246 vm_exit_during_initialization("GCPauseIntervalMillis should be "
247 "greater than 0");
248 }
249 }
250
251 // Then, if the pause time target parameter was not set, set it to
252 // the default value.
253 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
254 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
255 // The default pause time target in G1 is 200ms
256 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
257 } else {
258 // We do not allow the pause interval to be set without the
259 // pause time target
260 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
261 "without setting MaxGCPauseMillis");
262 }
263 }
264
265 // Then, if the interval parameter was not set, set it according to
266 // the pause time target (this will also deal with the case when the
267 // pause time target is the default value).
268 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
269 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
270 }
271
272 // Finally, make sure that the two parameters are consistent.
273 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
274 char buffer[256];
275 jio_snprintf(buffer, 256,
276 "MaxGCPauseMillis (%u) should be less than "
277 "GCPauseIntervalMillis (%u)",
278 MaxGCPauseMillis, GCPauseIntervalMillis);
279 vm_exit_during_initialization(buffer);
280 }
281
282 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
283 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
284 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
285
286 uintx confidence_perc = G1ConfidencePercent;
287 // Put an artificial ceiling on this so that it's not set to a silly value.
288 if (confidence_perc > 100) {
289 confidence_perc = 100;
290 warning("G1ConfidencePercent is set to a value that is too large, "
291 "it's been updated to %u", confidence_perc);
292 }
293 _sigma = (double) confidence_perc / 100.0;
294
295 // start conservatively (around 50ms is about right)
296 _concurrent_mark_remark_times_ms->add(0.05);
297 _concurrent_mark_cleanup_times_ms->add(0.20);
298 _tenuring_threshold = MaxTenuringThreshold;
299 // _max_survivor_regions will be calculated by
300 // update_young_list_target_length() during initialization.
301 _max_survivor_regions = 0;
302
303 assert(GCTimeRatio > 0,
304 "we should have set it to a default value set_g1_gc_flags() "
305 "if a user set it to 0");
306 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
307
308 uintx reserve_perc = G1ReservePercent;
309 // Put an artificial ceiling on this so that it's not set to a silly value.
310 if (reserve_perc > 50) {
311 reserve_perc = 50;
312 warning("G1ReservePercent is set to a value that is too large, "
313 "it's been updated to %u", reserve_perc);
314 }
315 _reserve_factor = (double) reserve_perc / 100.0;
316 // This will be set when the heap is expanded
317 // for the first time during initialization.
318 _reserve_regions = 0;
319
320 _collectionSetChooser = new CollectionSetChooser();
321 }
322
323 void G1CollectorPolicy::initialize_alignments() {
324 _space_alignment = HeapRegion::GrainBytes;
325 size_t card_table_alignment = GenRemSet::max_alignment_constraint();
326 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
327 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
328 }
329
330 void G1CollectorPolicy::initialize_flags() {
331 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
332 FLAG_SET_ERGO(uintx, G1HeapRegionSize, HeapRegion::GrainBytes);
333 }
334
335 if (SurvivorRatio < 1) {
336 vm_exit_during_initialization("Invalid survivor ratio specified");
337 }
338 CollectorPolicy::initialize_flags();
339 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
340 }
341
342 void G1CollectorPolicy::post_heap_initialize() {
343 uintx max_regions = G1CollectedHeap::heap()->max_regions();
344 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
345 if (max_young_size != MaxNewSize) {
346 FLAG_SET_ERGO(uintx, MaxNewSize, max_young_size);
347 }
348 }
349
350 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
351 _min_desired_young_length(0), _max_desired_young_length(0) {
352 if (FLAG_IS_CMDLINE(NewRatio)) {
353 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
354 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
355 } else {
356 _sizer_kind = SizerNewRatio;
357 _adaptive_size = false;
358 return;
359 }
360 }
361
362 if (NewSize > MaxNewSize) {
363 if (FLAG_IS_CMDLINE(MaxNewSize)) {
364 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
365 "A new max generation size of " SIZE_FORMAT "k will be used.",
366 NewSize/K, MaxNewSize/K, NewSize/K);
367 }
368 MaxNewSize = NewSize;
369 }
370
371 if (FLAG_IS_CMDLINE(NewSize)) {
372 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
373 1U);
374 if (FLAG_IS_CMDLINE(MaxNewSize)) {
375 _max_desired_young_length =
376 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
377 1U);
378 _sizer_kind = SizerMaxAndNewSize;
379 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
380 } else {
381 _sizer_kind = SizerNewSizeOnly;
382 }
383 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
384 _max_desired_young_length =
385 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
386 1U);
387 _sizer_kind = SizerMaxNewSizeOnly;
388 }
389 }
390
391 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
392 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
393 return MAX2(1U, default_value);
394 }
395
396 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
397 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
398 return MAX2(1U, default_value);
399 }
400
401 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
402 assert(number_of_heap_regions > 0, "Heap must be initialized");
403
404 switch (_sizer_kind) {
405 case SizerDefaults:
406 *min_young_length = calculate_default_min_length(number_of_heap_regions);
407 *max_young_length = calculate_default_max_length(number_of_heap_regions);
408 break;
409 case SizerNewSizeOnly:
410 *max_young_length = calculate_default_max_length(number_of_heap_regions);
411 *max_young_length = MAX2(*min_young_length, *max_young_length);
412 break;
413 case SizerMaxNewSizeOnly:
414 *min_young_length = calculate_default_min_length(number_of_heap_regions);
415 *min_young_length = MIN2(*min_young_length, *max_young_length);
416 break;
417 case SizerMaxAndNewSize:
418 // Do nothing. Values set on the command line, don't update them at runtime.
419 break;
420 case SizerNewRatio:
421 *min_young_length = number_of_heap_regions / (NewRatio + 1);
422 *max_young_length = *min_young_length;
423 break;
424 default:
425 ShouldNotReachHere();
426 }
427
428 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
429 }
430
431 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
432 // We need to pass the desired values because recalculation may not update these
433 // values in some cases.
434 uint temp = _min_desired_young_length;
435 uint result = _max_desired_young_length;
436 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
437 return result;
438 }
439
440 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
441 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
442 &_max_desired_young_length);
443 }
444
445 void G1CollectorPolicy::init() {
446 // Set aside an initial future to_space.
447 _g1 = G1CollectedHeap::heap();
448
449 assert(Heap_lock->owned_by_self(), "Locking discipline.");
450
451 initialize_gc_policy_counters();
452
453 if (adaptive_young_list_length()) {
454 _young_list_fixed_length = 0;
455 } else {
456 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
457 }
458 _free_regions_at_end_of_collection = _g1->num_free_regions();
459 update_young_list_target_length();
460
461 // We may immediately start allocating regions and placing them on the
462 // collection set list. Initialize the per-collection set info
463 start_incremental_cset_building();
464 }
465
466 // Create the jstat counters for the policy.
467 void G1CollectorPolicy::initialize_gc_policy_counters() {
468 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
469 }
470
471 bool G1CollectorPolicy::predict_will_fit(uint young_length,
472 double base_time_ms,
473 uint base_free_regions,
474 double target_pause_time_ms) {
475 if (young_length >= base_free_regions) {
476 // end condition 1: not enough space for the young regions
477 return false;
478 }
479
480 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
481 size_t bytes_to_copy =
482 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
483 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
484 double young_other_time_ms = predict_young_other_time_ms(young_length);
485 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
486 if (pause_time_ms > target_pause_time_ms) {
487 // end condition 2: prediction is over the target pause time
488 return false;
489 }
490
491 size_t free_bytes =
492 (base_free_regions - young_length) * HeapRegion::GrainBytes;
493 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
494 // end condition 3: out-of-space (conservatively!)
495 return false;
496 }
497
498 // success!
499 return true;
500 }
501
502 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
503 // re-calculate the necessary reserve
504 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
505 // We use ceiling so that if reserve_regions_d is > 0.0 (but
506 // smaller than 1.0) we'll get 1.
507 _reserve_regions = (uint) ceil(reserve_regions_d);
508
509 _young_gen_sizer->heap_size_changed(new_number_of_regions);
510 }
511
512 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
513 uint base_min_length) {
514 uint desired_min_length = 0;
515 if (adaptive_young_list_length()) {
516 if (_alloc_rate_ms_seq->num() > 3) {
517 double now_sec = os::elapsedTime();
518 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
519 double alloc_rate_ms = predict_alloc_rate_ms();
520 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
521 } else {
522 // otherwise we don't have enough info to make the prediction
523 }
524 }
525 desired_min_length += base_min_length;
526 // make sure we don't go below any user-defined minimum bound
527 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
528 }
529
530 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
531 // Here, we might want to also take into account any additional
532 // constraints (i.e., user-defined minimum bound). Currently, we
533 // effectively don't set this bound.
534 return _young_gen_sizer->max_desired_young_length();
535 }
536
537 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
538 if (rs_lengths == (size_t) -1) {
539 // if it's set to the default value (-1), we should predict it;
540 // otherwise, use the given value.
541 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
542 }
543
544 // Calculate the absolute and desired min bounds.
545
546 // This is how many young regions we already have (currently: the survivors).
547 uint base_min_length = recorded_survivor_regions();
548 // This is the absolute minimum young length, which ensures that we
549 // can allocate one eden region in the worst-case.
550 uint absolute_min_length = base_min_length + 1;
551 uint desired_min_length =
552 calculate_young_list_desired_min_length(base_min_length);
553 if (desired_min_length < absolute_min_length) {
554 desired_min_length = absolute_min_length;
555 }
556
557 // Calculate the absolute and desired max bounds.
558
559 // We will try our best not to "eat" into the reserve.
560 uint absolute_max_length = 0;
561 if (_free_regions_at_end_of_collection > _reserve_regions) {
562 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
563 }
564 uint desired_max_length = calculate_young_list_desired_max_length();
565 if (desired_max_length > absolute_max_length) {
566 desired_max_length = absolute_max_length;
567 }
568
569 uint young_list_target_length = 0;
570 if (adaptive_young_list_length()) {
571 if (gcs_are_young()) {
572 young_list_target_length =
573 calculate_young_list_target_length(rs_lengths,
574 base_min_length,
575 desired_min_length,
576 desired_max_length);
577 _rs_lengths_prediction = rs_lengths;
578 } else {
579 // Don't calculate anything and let the code below bound it to
580 // the desired_min_length, i.e., do the next GC as soon as
581 // possible to maximize how many old regions we can add to it.
582 }
583 } else {
584 // The user asked for a fixed young gen so we'll fix the young gen
585 // whether the next GC is young or mixed.
586 young_list_target_length = _young_list_fixed_length;
587 }
588
589 // Make sure we don't go over the desired max length, nor under the
590 // desired min length. In case they clash, desired_min_length wins
591 // which is why that test is second.
592 if (young_list_target_length > desired_max_length) {
593 young_list_target_length = desired_max_length;
594 }
595 if (young_list_target_length < desired_min_length) {
596 young_list_target_length = desired_min_length;
597 }
598
599 assert(young_list_target_length > recorded_survivor_regions(),
600 "we should be able to allocate at least one eden region");
601 assert(young_list_target_length >= absolute_min_length, "post-condition");
602 _young_list_target_length = young_list_target_length;
603
604 update_max_gc_locker_expansion();
605 }
606
607 uint
608 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
609 uint base_min_length,
610 uint desired_min_length,
611 uint desired_max_length) {
612 assert(adaptive_young_list_length(), "pre-condition");
613 assert(gcs_are_young(), "only call this for young GCs");
614
615 // In case some edge-condition makes the desired max length too small...
616 if (desired_max_length <= desired_min_length) {
617 return desired_min_length;
618 }
619
620 // We'll adjust min_young_length and max_young_length not to include
621 // the already allocated young regions (i.e., so they reflect the
622 // min and max eden regions we'll allocate). The base_min_length
623 // will be reflected in the predictions by the
624 // survivor_regions_evac_time prediction.
625 assert(desired_min_length > base_min_length, "invariant");
626 uint min_young_length = desired_min_length - base_min_length;
627 assert(desired_max_length > base_min_length, "invariant");
628 uint max_young_length = desired_max_length - base_min_length;
629
630 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
631 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
632 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
633 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
634 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
635 double base_time_ms =
636 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
637 survivor_regions_evac_time;
638 uint available_free_regions = _free_regions_at_end_of_collection;
639 uint base_free_regions = 0;
640 if (available_free_regions > _reserve_regions) {
641 base_free_regions = available_free_regions - _reserve_regions;
642 }
643
644 // Here, we will make sure that the shortest young length that
645 // makes sense fits within the target pause time.
646
647 if (predict_will_fit(min_young_length, base_time_ms,
648 base_free_regions, target_pause_time_ms)) {
649 // The shortest young length will fit into the target pause time;
650 // we'll now check whether the absolute maximum number of young
651 // regions will fit in the target pause time. If not, we'll do
652 // a binary search between min_young_length and max_young_length.
653 if (predict_will_fit(max_young_length, base_time_ms,
654 base_free_regions, target_pause_time_ms)) {
655 // The maximum young length will fit into the target pause time.
656 // We are done so set min young length to the maximum length (as
657 // the result is assumed to be returned in min_young_length).
658 min_young_length = max_young_length;
659 } else {
660 // The maximum possible number of young regions will not fit within
661 // the target pause time so we'll search for the optimal
662 // length. The loop invariants are:
663 //
664 // min_young_length < max_young_length
665 // min_young_length is known to fit into the target pause time
666 // max_young_length is known not to fit into the target pause time
667 //
668 // Going into the loop we know the above hold as we've just
669 // checked them. Every time around the loop we check whether
670 // the middle value between min_young_length and
671 // max_young_length fits into the target pause time. If it
672 // does, it becomes the new min. If it doesn't, it becomes
673 // the new max. This way we maintain the loop invariants.
674
675 assert(min_young_length < max_young_length, "invariant");
676 uint diff = (max_young_length - min_young_length) / 2;
677 while (diff > 0) {
678 uint young_length = min_young_length + diff;
679 if (predict_will_fit(young_length, base_time_ms,
680 base_free_regions, target_pause_time_ms)) {
681 min_young_length = young_length;
682 } else {
683 max_young_length = young_length;
684 }
685 assert(min_young_length < max_young_length, "invariant");
686 diff = (max_young_length - min_young_length) / 2;
687 }
688 // The results is min_young_length which, according to the
689 // loop invariants, should fit within the target pause time.
690
691 // These are the post-conditions of the binary search above:
692 assert(min_young_length < max_young_length,
693 "otherwise we should have discovered that max_young_length "
694 "fits into the pause target and not done the binary search");
695 assert(predict_will_fit(min_young_length, base_time_ms,
696 base_free_regions, target_pause_time_ms),
697 "min_young_length, the result of the binary search, should "
698 "fit into the pause target");
699 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
700 base_free_regions, target_pause_time_ms),
701 "min_young_length, the result of the binary search, should be "
702 "optimal, so no larger length should fit into the pause target");
703 }
704 } else {
705 // Even the minimum length doesn't fit into the pause time
706 // target, return it as the result nevertheless.
707 }
708 return base_min_length + min_young_length;
709 }
710
711 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
712 double survivor_regions_evac_time = 0.0;
713 for (HeapRegion * r = _recorded_survivor_head;
714 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
715 r = r->get_next_young_region()) {
716 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
717 }
718 return survivor_regions_evac_time;
719 }
720
721 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
722 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
723
724 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
725 if (rs_lengths > _rs_lengths_prediction) {
726 // add 10% to avoid having to recalculate often
727 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
728 update_young_list_target_length(rs_lengths_prediction);
729 }
730 }
731
732
733
734 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
735 bool is_tlab,
736 bool* gc_overhead_limit_was_exceeded) {
737 guarantee(false, "Not using this policy feature yet.");
738 return NULL;
739 }
740
741 // This method controls how a collector handles one or more
742 // of its generations being fully allocated.
743 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
744 bool is_tlab) {
745 guarantee(false, "Not using this policy feature yet.");
746 return NULL;
747 }
748
749
750 #ifndef PRODUCT
751 bool G1CollectorPolicy::verify_young_ages() {
752 HeapRegion* head = _g1->young_list()->first_region();
753 return
754 verify_young_ages(head, _short_lived_surv_rate_group);
755 // also call verify_young_ages on any additional surv rate groups
756 }
757
758 bool
759 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
760 SurvRateGroup *surv_rate_group) {
761 guarantee( surv_rate_group != NULL, "pre-condition" );
762
763 const char* name = surv_rate_group->name();
764 bool ret = true;
765 int prev_age = -1;
766
767 for (HeapRegion* curr = head;
768 curr != NULL;
769 curr = curr->get_next_young_region()) {
770 SurvRateGroup* group = curr->surv_rate_group();
771 if (group == NULL && !curr->is_survivor()) {
772 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
773 ret = false;
774 }
775
776 if (surv_rate_group == group) {
777 int age = curr->age_in_surv_rate_group();
778
779 if (age < 0) {
780 gclog_or_tty->print_cr("## %s: encountered negative age", name);
781 ret = false;
782 }
783
784 if (age <= prev_age) {
785 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
786 "(%d, %d)", name, age, prev_age);
787 ret = false;
788 }
789 prev_age = age;
790 }
791 }
792
793 return ret;
794 }
795 #endif // PRODUCT
796
797 void G1CollectorPolicy::record_full_collection_start() {
798 _full_collection_start_sec = os::elapsedTime();
799 record_heap_size_info_at_start(true /* full */);
800 // Release the future to-space so that it is available for compaction into.
801 _g1->set_full_collection();
802 }
803
804 void G1CollectorPolicy::record_full_collection_end() {
805 // Consider this like a collection pause for the purposes of allocation
806 // since last pause.
807 double end_sec = os::elapsedTime();
808 double full_gc_time_sec = end_sec - _full_collection_start_sec;
809 double full_gc_time_ms = full_gc_time_sec * 1000.0;
810
811 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
812
813 update_recent_gc_times(end_sec, full_gc_time_ms);
814
815 _g1->clear_full_collection();
816
817 // "Nuke" the heuristics that control the young/mixed GC
818 // transitions and make sure we start with young GCs after the Full GC.
819 set_gcs_are_young(true);
820 _last_young_gc = false;
821 clear_initiate_conc_mark_if_possible();
822 clear_during_initial_mark_pause();
823 _in_marking_window = false;
824 _in_marking_window_im = false;
825
826 _short_lived_surv_rate_group->start_adding_regions();
827 // also call this on any additional surv rate groups
828
829 record_survivor_regions(0, NULL, NULL);
830
831 _free_regions_at_end_of_collection = _g1->num_free_regions();
832 // Reset survivors SurvRateGroup.
833 _survivor_surv_rate_group->reset();
834 update_young_list_target_length();
835 _collectionSetChooser->clear();
836 }
837
838 void G1CollectorPolicy::record_stop_world_start() {
839 _stop_world_start = os::elapsedTime();
840 }
841
842 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
843 // We only need to do this here as the policy will only be applied
844 // to the GC we're about to start. so, no point is calculating this
845 // every time we calculate / recalculate the target young length.
846 update_survivors_policy();
847
848 assert(_g1->used() == _g1->recalculate_used(),
849 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
850 _g1->used(), _g1->recalculate_used()));
851
852 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
853 _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
854 _stop_world_start = 0.0;
855
856 record_heap_size_info_at_start(false /* full */);
857
858 phase_times()->record_cur_collection_start_sec(start_time_sec);
859 _pending_cards = _g1->pending_card_num();
860
861 _collection_set_bytes_used_before = 0;
862 _bytes_copied_during_gc = 0;
863
864 _last_gc_was_young = false;
865
866 // do that for any other surv rate groups
867 _short_lived_surv_rate_group->stop_adding_regions();
868 _survivors_age_table.clear();
869
870 assert( verify_young_ages(), "region age verification" );
871 }
872
873 void G1CollectorPolicy::record_concurrent_mark_init_end(double
874 mark_init_elapsed_time_ms) {
875 _during_marking = true;
876 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
877 clear_during_initial_mark_pause();
878 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
879 }
880
881 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
882 _mark_remark_start_sec = os::elapsedTime();
883 _during_marking = false;
884 }
885
886 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
887 double end_time_sec = os::elapsedTime();
888 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
889 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
890 _cur_mark_stop_world_time_ms += elapsed_time_ms;
891 _prev_collection_pause_end_ms += elapsed_time_ms;
892
893 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
894 }
895
896 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
897 _mark_cleanup_start_sec = os::elapsedTime();
898 }
899
900 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
901 _last_young_gc = true;
902 _in_marking_window = false;
903 }
904
905 void G1CollectorPolicy::record_concurrent_pause() {
906 if (_stop_world_start > 0.0) {
907 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
908 _trace_young_gen_time_data.record_yield_time(yield_ms);
909 }
910 }
911
912 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
913 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
914 return false;
915 }
916
917 size_t marking_initiating_used_threshold =
918 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
919 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
920 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
921
922 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
923 if (gcs_are_young() && !_last_young_gc) {
924 ergo_verbose5(ErgoConcCycles,
925 "request concurrent cycle initiation",
926 ergo_format_reason("occupancy higher than threshold")
927 ergo_format_byte("occupancy")
928 ergo_format_byte("allocation request")
929 ergo_format_byte_perc("threshold")
930 ergo_format_str("source"),
931 cur_used_bytes,
932 alloc_byte_size,
933 marking_initiating_used_threshold,
934 (double) InitiatingHeapOccupancyPercent,
935 source);
936 return true;
937 } else {
938 ergo_verbose5(ErgoConcCycles,
939 "do not request concurrent cycle initiation",
940 ergo_format_reason("still doing mixed collections")
941 ergo_format_byte("occupancy")
942 ergo_format_byte("allocation request")
943 ergo_format_byte_perc("threshold")
944 ergo_format_str("source"),
945 cur_used_bytes,
946 alloc_byte_size,
947 marking_initiating_used_threshold,
948 (double) InitiatingHeapOccupancyPercent,
949 source);
950 }
951 }
952
953 return false;
954 }
955
956 // Anything below that is considered to be zero
957 #define MIN_TIMER_GRANULARITY 0.0000001
958
959 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {
960 double end_time_sec = os::elapsedTime();
961 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
962 "otherwise, the subtraction below does not make sense");
963 size_t rs_size =
964 _cur_collection_pause_used_regions_at_start - cset_region_length();
965 size_t cur_used_bytes = _g1->used();
966 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
967 bool last_pause_included_initial_mark = false;
968 bool update_stats = !_g1->evacuation_failed();
969
970 #ifndef PRODUCT
971 if (G1YoungSurvRateVerbose) {
972 gclog_or_tty->cr();
973 _short_lived_surv_rate_group->print();
974 // do that for any other surv rate groups too
975 }
976 #endif // PRODUCT
977
978 last_pause_included_initial_mark = during_initial_mark_pause();
979 if (last_pause_included_initial_mark) {
980 record_concurrent_mark_init_end(0.0);
981 } else if (need_to_start_conc_mark("end of GC")) {
982 // Note: this might have already been set, if during the last
983 // pause we decided to start a cycle but at the beginning of
984 // this pause we decided to postpone it. That's OK.
985 set_initiate_conc_mark_if_possible();
986 }
987
988 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
989 end_time_sec, false);
990
991 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);
992 evacuation_info.set_bytes_copied(_bytes_copied_during_gc);
993
994 if (update_stats) {
995 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
996 // this is where we update the allocation rate of the application
997 double app_time_ms =
998 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
999 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1000 // This usually happens due to the timer not having the required
1001 // granularity. Some Linuxes are the usual culprits.
1002 // We'll just set it to something (arbitrarily) small.
1003 app_time_ms = 1.0;
1004 }
1005 // We maintain the invariant that all objects allocated by mutator
1006 // threads will be allocated out of eden regions. So, we can use
1007 // the eden region number allocated since the previous GC to
1008 // calculate the application's allocate rate. The only exception
1009 // to that is humongous objects that are allocated separately. But
1010 // given that humongous object allocations do not really affect
1011 // either the pause's duration nor when the next pause will take
1012 // place we can safely ignore them here.
1013 uint regions_allocated = eden_cset_region_length();
1014 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1015 _alloc_rate_ms_seq->add(alloc_rate_ms);
1016
1017 double interval_ms =
1018 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1019 update_recent_gc_times(end_time_sec, pause_time_ms);
1020 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1021 if (recent_avg_pause_time_ratio() < 0.0 ||
1022 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1023 #ifndef PRODUCT
1024 // Dump info to allow post-facto debugging
1025 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1026 gclog_or_tty->print_cr("-------------------------------------------");
1027 gclog_or_tty->print_cr("Recent GC Times (ms):");
1028 _recent_gc_times_ms->dump();
1029 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1030 _recent_prev_end_times_for_all_gcs_sec->dump();
1031 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1032 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1033 // In debug mode, terminate the JVM if the user wants to debug at this point.
1034 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1035 #endif // !PRODUCT
1036 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1037 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1038 if (_recent_avg_pause_time_ratio < 0.0) {
1039 _recent_avg_pause_time_ratio = 0.0;
1040 } else {
1041 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1042 _recent_avg_pause_time_ratio = 1.0;
1043 }
1044 }
1045 }
1046
1047 bool new_in_marking_window = _in_marking_window;
1048 bool new_in_marking_window_im = false;
1049 if (last_pause_included_initial_mark) {
1050 new_in_marking_window = true;
1051 new_in_marking_window_im = true;
1052 }
1053
1054 if (_last_young_gc) {
1055 // This is supposed to to be the "last young GC" before we start
1056 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1057
1058 if (!last_pause_included_initial_mark) {
1059 if (next_gc_should_be_mixed("start mixed GCs",
1060 "do not start mixed GCs")) {
1061 set_gcs_are_young(false);
1062 }
1063 } else {
1064 ergo_verbose0(ErgoMixedGCs,
1065 "do not start mixed GCs",
1066 ergo_format_reason("concurrent cycle is about to start"));
1067 }
1068 _last_young_gc = false;
1069 }
1070
1071 if (!_last_gc_was_young) {
1072 // This is a mixed GC. Here we decide whether to continue doing
1073 // mixed GCs or not.
1074
1075 if (!next_gc_should_be_mixed("continue mixed GCs",
1076 "do not continue mixed GCs")) {
1077 set_gcs_are_young(true);
1078 }
1079 }
1080
1081 _short_lived_surv_rate_group->start_adding_regions();
1082 // Do that for any other surv rate groups
1083
1084 if (update_stats) {
1085 double cost_per_card_ms = 0.0;
1086 if (_pending_cards > 0) {
1087 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1088 _cost_per_card_ms_seq->add(cost_per_card_ms);
1089 }
1090
1091 size_t cards_scanned = _g1->cards_scanned();
1092
1093 double cost_per_entry_ms = 0.0;
1094 if (cards_scanned > 10) {
1095 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1096 if (_last_gc_was_young) {
1097 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1098 } else {
1099 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1100 }
1101 }
1102
1103 if (_max_rs_lengths > 0) {
1104 double cards_per_entry_ratio =
1105 (double) cards_scanned / (double) _max_rs_lengths;
1106 if (_last_gc_was_young) {
1107 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1108 } else {
1109 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1110 }
1111 }
1112
1113 // This is defensive. For a while _max_rs_lengths could get
1114 // smaller than _recorded_rs_lengths which was causing
1115 // rs_length_diff to get very large and mess up the RSet length
1116 // predictions. The reason was unsafe concurrent updates to the
1117 // _inc_cset_recorded_rs_lengths field which the code below guards
1118 // against (see CR 7118202). This bug has now been fixed (see CR
1119 // 7119027). However, I'm still worried that
1120 // _inc_cset_recorded_rs_lengths might still end up somewhat
1121 // inaccurate. The concurrent refinement thread calculates an
1122 // RSet's length concurrently with other CR threads updating it
1123 // which might cause it to calculate the length incorrectly (if,
1124 // say, it's in mid-coarsening). So I'll leave in the defensive
1125 // conditional below just in case.
1126 size_t rs_length_diff = 0;
1127 if (_max_rs_lengths > _recorded_rs_lengths) {
1128 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1129 }
1130 _rs_length_diff_seq->add((double) rs_length_diff);
1131
1132 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1133 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1134 double cost_per_byte_ms = 0.0;
1135
1136 if (copied_bytes > 0) {
1137 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1138 if (_in_marking_window) {
1139 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1140 } else {
1141 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1142 }
1143 }
1144
1145 double all_other_time_ms = pause_time_ms -
1146 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1147 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1148
1149 double young_other_time_ms = 0.0;
1150 if (young_cset_region_length() > 0) {
1151 young_other_time_ms =
1152 phase_times()->young_cset_choice_time_ms() +
1153 phase_times()->young_free_cset_time_ms();
1154 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1155 (double) young_cset_region_length());
1156 }
1157 double non_young_other_time_ms = 0.0;
1158 if (old_cset_region_length() > 0) {
1159 non_young_other_time_ms =
1160 phase_times()->non_young_cset_choice_time_ms() +
1161 phase_times()->non_young_free_cset_time_ms();
1162
1163 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1164 (double) old_cset_region_length());
1165 }
1166
1167 double constant_other_time_ms = all_other_time_ms -
1168 (young_other_time_ms + non_young_other_time_ms);
1169 _constant_other_time_ms_seq->add(constant_other_time_ms);
1170
1171 double survival_ratio = 0.0;
1172 if (_collection_set_bytes_used_before > 0) {
1173 survival_ratio = (double) _bytes_copied_during_gc /
1174 (double) _collection_set_bytes_used_before;
1175 }
1176
1177 _pending_cards_seq->add((double) _pending_cards);
1178 _rs_lengths_seq->add((double) _max_rs_lengths);
1179 }
1180
1181 _in_marking_window = new_in_marking_window;
1182 _in_marking_window_im = new_in_marking_window_im;
1183 _free_regions_at_end_of_collection = _g1->num_free_regions();
1184 update_young_list_target_length();
1185
1186 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1187 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1188 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1189 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1190
1191 _collectionSetChooser->verify();
1192 }
1193
1194 #define EXT_SIZE_FORMAT "%.1f%s"
1195 #define EXT_SIZE_PARAMS(bytes) \
1196 byte_size_in_proper_unit((double)(bytes)), \
1197 proper_unit_for_byte_size((bytes))
1198
1199 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1200 YoungList* young_list = _g1->young_list();
1201 _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1202 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1203 _heap_capacity_bytes_before_gc = _g1->capacity();
1204 _heap_used_bytes_before_gc = _g1->used();
1205 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1206
1207 _eden_capacity_bytes_before_gc =
1208 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1209
1210 if (full) {
1211 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1212 }
1213 }
1214
1215 void G1CollectorPolicy::print_heap_transition() {
1216 _g1->print_size_transition(gclog_or_tty,
1217 _heap_used_bytes_before_gc,
1218 _g1->used(),
1219 _g1->capacity());
1220 }
1221
1222 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {
1223 YoungList* young_list = _g1->young_list();
1224
1225 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1226 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1227 size_t heap_used_bytes_after_gc = _g1->used();
1228
1229 size_t heap_capacity_bytes_after_gc = _g1->capacity();
1230 size_t eden_capacity_bytes_after_gc =
1231 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1232
1233 gclog_or_tty->print(
1234 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1235 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1236 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1237 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1238 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1239 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1240 EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1241 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1242 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1243 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1244 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1245 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1246 EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1247 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1248
1249 if (full) {
1250 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1251 }
1252
1253 gclog_or_tty->cr();
1254 }
1255
1256 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1257 double update_rs_processed_buffers,
1258 double goal_ms) {
1259 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1260 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1261
1262 if (G1UseAdaptiveConcRefinement) {
1263 const int k_gy = 3, k_gr = 6;
1264 const double inc_k = 1.1, dec_k = 0.9;
1265
1266 int g = cg1r->green_zone();
1267 if (update_rs_time > goal_ms) {
1268 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1269 } else {
1270 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1271 g = (int)MAX2(g * inc_k, g + 1.0);
1272 }
1273 }
1274 // Change the refinement threads params
1275 cg1r->set_green_zone(g);
1276 cg1r->set_yellow_zone(g * k_gy);
1277 cg1r->set_red_zone(g * k_gr);
1278 cg1r->reinitialize_threads();
1279
1280 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1281 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1282 cg1r->yellow_zone());
1283 // Change the barrier params
1284 dcqs.set_process_completed_threshold(processing_threshold);
1285 dcqs.set_max_completed_queue(cg1r->red_zone());
1286 }
1287
1288 int curr_queue_size = dcqs.completed_buffers_num();
1289 if (curr_queue_size >= cg1r->yellow_zone()) {
1290 dcqs.set_completed_queue_padding(curr_queue_size);
1291 } else {
1292 dcqs.set_completed_queue_padding(0);
1293 }
1294 dcqs.notify_if_necessary();
1295 }
1296
1297 double
1298 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1299 size_t scanned_cards) {
1300 return
1301 predict_rs_update_time_ms(pending_cards) +
1302 predict_rs_scan_time_ms(scanned_cards) +
1303 predict_constant_other_time_ms();
1304 }
1305
1306 double
1307 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1308 size_t rs_length = predict_rs_length_diff();
1309 size_t card_num;
1310 if (gcs_are_young()) {
1311 card_num = predict_young_card_num(rs_length);
1312 } else {
1313 card_num = predict_non_young_card_num(rs_length);
1314 }
1315 return predict_base_elapsed_time_ms(pending_cards, card_num);
1316 }
1317
1318 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1319 size_t bytes_to_copy;
1320 if (hr->is_marked())
1321 bytes_to_copy = hr->max_live_bytes();
1322 else {
1323 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1324 int age = hr->age_in_surv_rate_group();
1325 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1326 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1327 }
1328 return bytes_to_copy;
1329 }
1330
1331 double
1332 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1333 bool for_young_gc) {
1334 size_t rs_length = hr->rem_set()->occupied();
1335 size_t card_num;
1336
1337 // Predicting the number of cards is based on which type of GC
1338 // we're predicting for.
1339 if (for_young_gc) {
1340 card_num = predict_young_card_num(rs_length);
1341 } else {
1342 card_num = predict_non_young_card_num(rs_length);
1343 }
1344 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1345
1346 double region_elapsed_time_ms =
1347 predict_rs_scan_time_ms(card_num) +
1348 predict_object_copy_time_ms(bytes_to_copy);
1349
1350 // The prediction of the "other" time for this region is based
1351 // upon the region type and NOT the GC type.
1352 if (hr->is_young()) {
1353 region_elapsed_time_ms += predict_young_other_time_ms(1);
1354 } else {
1355 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1356 }
1357 return region_elapsed_time_ms;
1358 }
1359
1360 void
1361 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1362 uint survivor_cset_region_length) {
1363 _eden_cset_region_length = eden_cset_region_length;
1364 _survivor_cset_region_length = survivor_cset_region_length;
1365 _old_cset_region_length = 0;
1366 }
1367
1368 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1369 _recorded_rs_lengths = rs_lengths;
1370 }
1371
1372 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1373 double elapsed_ms) {
1374 _recent_gc_times_ms->add(elapsed_ms);
1375 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1376 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1377 }
1378
1379 size_t G1CollectorPolicy::expansion_amount() {
1380 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1381 double threshold = _gc_overhead_perc;
1382 if (recent_gc_overhead > threshold) {
1383 // We will double the existing space, or take
1384 // G1ExpandByPercentOfAvailable % of the available expansion
1385 // space, whichever is smaller, bounded below by a minimum
1386 // expansion (unless that's all that's left.)
1387 const size_t min_expand_bytes = 1*M;
1388 size_t reserved_bytes = _g1->max_capacity();
1389 size_t committed_bytes = _g1->capacity();
1390 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1391 size_t expand_bytes;
1392 size_t expand_bytes_via_pct =
1393 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1394 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1395 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1396 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1397
1398 ergo_verbose5(ErgoHeapSizing,
1399 "attempt heap expansion",
1400 ergo_format_reason("recent GC overhead higher than "
1401 "threshold after GC")
1402 ergo_format_perc("recent GC overhead")
1403 ergo_format_perc("threshold")
1404 ergo_format_byte("uncommitted")
1405 ergo_format_byte_perc("calculated expansion amount"),
1406 recent_gc_overhead, threshold,
1407 uncommitted_bytes,
1408 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1409
1410 return expand_bytes;
1411 } else {
1412 return 0;
1413 }
1414 }
1415
1416 void G1CollectorPolicy::print_tracing_info() const {
1417 _trace_young_gen_time_data.print();
1418 _trace_old_gen_time_data.print();
1419 }
1420
1421 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1422 #ifndef PRODUCT
1423 _short_lived_surv_rate_group->print_surv_rate_summary();
1424 // add this call for any other surv rate groups
1425 #endif // PRODUCT
1426 }
1427
1428 uint G1CollectorPolicy::max_regions(int purpose) {
1429 switch (purpose) {
1430 case GCAllocForSurvived:
1431 return _max_survivor_regions;
1432 case GCAllocForTenured:
1433 return REGIONS_UNLIMITED;
1434 default:
1435 ShouldNotReachHere();
1436 return REGIONS_UNLIMITED;
1437 };
1438 }
1439
1440 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1441 uint expansion_region_num = 0;
1442 if (GCLockerEdenExpansionPercent > 0) {
1443 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1444 double expansion_region_num_d = perc * (double) _young_list_target_length;
1445 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1446 // less than 1.0) we'll get 1.
1447 expansion_region_num = (uint) ceil(expansion_region_num_d);
1448 } else {
1449 assert(expansion_region_num == 0, "sanity");
1450 }
1451 _young_list_max_length = _young_list_target_length + expansion_region_num;
1452 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1453 }
1454
1455 // Calculates survivor space parameters.
1456 void G1CollectorPolicy::update_survivors_policy() {
1457 double max_survivor_regions_d =
1458 (double) _young_list_target_length / (double) SurvivorRatio;
1459 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1460 // smaller than 1.0) we'll get 1.
1461 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1462
1463 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1464 HeapRegion::GrainWords * _max_survivor_regions);
1465 }
1466
1467 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1468 GCCause::Cause gc_cause) {
1469 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1470 if (!during_cycle) {
1471 ergo_verbose1(ErgoConcCycles,
1472 "request concurrent cycle initiation",
1473 ergo_format_reason("requested by GC cause")
1474 ergo_format_str("GC cause"),
1475 GCCause::to_string(gc_cause));
1476 set_initiate_conc_mark_if_possible();
1477 return true;
1478 } else {
1479 ergo_verbose1(ErgoConcCycles,
1480 "do not request concurrent cycle initiation",
1481 ergo_format_reason("concurrent cycle already in progress")
1482 ergo_format_str("GC cause"),
1483 GCCause::to_string(gc_cause));
1484 return false;
1485 }
1486 }
1487
1488 void
1489 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1490 // We are about to decide on whether this pause will be an
1491 // initial-mark pause.
1492
1493 // First, during_initial_mark_pause() should not be already set. We
1494 // will set it here if we have to. However, it should be cleared by
1495 // the end of the pause (it's only set for the duration of an
1496 // initial-mark pause).
1497 assert(!during_initial_mark_pause(), "pre-condition");
1498
1499 if (initiate_conc_mark_if_possible()) {
1500 // We had noticed on a previous pause that the heap occupancy has
1501 // gone over the initiating threshold and we should start a
1502 // concurrent marking cycle. So we might initiate one.
1503
1504 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1505 if (!during_cycle) {
1506 // The concurrent marking thread is not "during a cycle", i.e.,
1507 // it has completed the last one. So we can go ahead and
1508 // initiate a new cycle.
1509
1510 set_during_initial_mark_pause();
1511 // We do not allow mixed GCs during marking.
1512 if (!gcs_are_young()) {
1513 set_gcs_are_young(true);
1514 ergo_verbose0(ErgoMixedGCs,
1515 "end mixed GCs",
1516 ergo_format_reason("concurrent cycle is about to start"));
1517 }
1518
1519 // And we can now clear initiate_conc_mark_if_possible() as
1520 // we've already acted on it.
1521 clear_initiate_conc_mark_if_possible();
1522
1523 ergo_verbose0(ErgoConcCycles,
1524 "initiate concurrent cycle",
1525 ergo_format_reason("concurrent cycle initiation requested"));
1526 } else {
1527 // The concurrent marking thread is still finishing up the
1528 // previous cycle. If we start one right now the two cycles
1529 // overlap. In particular, the concurrent marking thread might
1530 // be in the process of clearing the next marking bitmap (which
1531 // we will use for the next cycle if we start one). Starting a
1532 // cycle now will be bad given that parts of the marking
1533 // information might get cleared by the marking thread. And we
1534 // cannot wait for the marking thread to finish the cycle as it
1535 // periodically yields while clearing the next marking bitmap
1536 // and, if it's in a yield point, it's waiting for us to
1537 // finish. So, at this point we will not start a cycle and we'll
1538 // let the concurrent marking thread complete the last one.
1539 ergo_verbose0(ErgoConcCycles,
1540 "do not initiate concurrent cycle",
1541 ergo_format_reason("concurrent cycle already in progress"));
1542 }
1543 }
1544 }
1545
1546 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1547 G1CollectedHeap* _g1h;
1548 CSetChooserParUpdater _cset_updater;
1549
1550 public:
1551 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1552 uint chunk_size) :
1553 _g1h(G1CollectedHeap::heap()),
1554 _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1555
1556 bool doHeapRegion(HeapRegion* r) {
1557 // Do we have any marking information for this region?
1558 if (r->is_marked()) {
1559 // We will skip any region that's currently used as an old GC
1560 // alloc region (we should not consider those for collection
1561 // before we fill them up).
1562 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1563 _cset_updater.add_region(r);
1564 }
1565 }
1566 return false;
1567 }
1568 };
1569
1570 class ParKnownGarbageTask: public AbstractGangTask {
1571 CollectionSetChooser* _hrSorted;
1572 uint _chunk_size;
1573 G1CollectedHeap* _g1;
1574 HeapRegionClaimer _hrclaimer;
1575
1576 public:
1577 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1578 AbstractGangTask("ParKnownGarbageTask"),
1579 _hrSorted(hrSorted), _chunk_size(chunk_size),
1580 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1581
1582 void work(uint worker_id) {
1583 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1584 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1585 }
1586 };
1587
1588 void
1589 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1590 _collectionSetChooser->clear();
1591
1592 uint region_num = _g1->num_regions();
1593 const uint OverpartitionFactor = 4;
1594 uint WorkUnit;
1595 // The use of MinChunkSize = 8 in the original code
1596 // causes some assertion failures when the total number of
1597 // region is less than 8. The code here tries to fix that.
1598 // Should the original code also be fixed?
1599 if (no_of_gc_threads > 0) {
1600 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1601 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1602 MinWorkUnit);
1603 } else {
1604 assert(no_of_gc_threads > 0,
1605 "The active gc workers should be greater than 0");
1606 // In a product build do something reasonable to avoid a crash.
1607 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1608 WorkUnit =
1609 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1610 MinWorkUnit);
1611 }
1612 _collectionSetChooser->prepare_for_par_region_addition(_g1->num_regions(),
1613 WorkUnit);
1614 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser, WorkUnit, (uint) no_of_gc_threads);
1615 _g1->workers()->run_task(&parKnownGarbageTask);
1616
1617 _collectionSetChooser->sort_regions();
1618
1619 double end_sec = os::elapsedTime();
1620 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1621 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1622 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1623 _prev_collection_pause_end_ms += elapsed_time_ms;
1624 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1625 }
1626
1627 // Add the heap region at the head of the non-incremental collection set
1628 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1629 assert(_inc_cset_build_state == Active, "Precondition");
1630 assert(hr->is_old(), "the region should be old");
1631
1632 assert(!hr->in_collection_set(), "should not already be in the CSet");
1633 hr->set_in_collection_set(true);
1634 hr->set_next_in_collection_set(_collection_set);
1635 _collection_set = hr;
1636 _collection_set_bytes_used_before += hr->used();
1637 _g1->register_region_with_in_cset_fast_test(hr);
1638 size_t rs_length = hr->rem_set()->occupied();
1639 _recorded_rs_lengths += rs_length;
1640 _old_cset_region_length += 1;
1641 }
1642
1643 // Initialize the per-collection-set information
1644 void G1CollectorPolicy::start_incremental_cset_building() {
1645 assert(_inc_cset_build_state == Inactive, "Precondition");
1646
1647 _inc_cset_head = NULL;
1648 _inc_cset_tail = NULL;
1649 _inc_cset_bytes_used_before = 0;
1650
1651 _inc_cset_max_finger = 0;
1652 _inc_cset_recorded_rs_lengths = 0;
1653 _inc_cset_recorded_rs_lengths_diffs = 0;
1654 _inc_cset_predicted_elapsed_time_ms = 0.0;
1655 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1656 _inc_cset_build_state = Active;
1657 }
1658
1659 void G1CollectorPolicy::finalize_incremental_cset_building() {
1660 assert(_inc_cset_build_state == Active, "Precondition");
1661 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1662
1663 // The two "main" fields, _inc_cset_recorded_rs_lengths and
1664 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1665 // that adds a new region to the CSet. Further updates by the
1666 // concurrent refinement thread that samples the young RSet lengths
1667 // are accumulated in the *_diffs fields. Here we add the diffs to
1668 // the "main" fields.
1669
1670 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1671 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1672 } else {
1673 // This is defensive. The diff should in theory be always positive
1674 // as RSets can only grow between GCs. However, given that we
1675 // sample their size concurrently with other threads updating them
1676 // it's possible that we might get the wrong size back, which
1677 // could make the calculations somewhat inaccurate.
1678 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1679 if (_inc_cset_recorded_rs_lengths >= diffs) {
1680 _inc_cset_recorded_rs_lengths -= diffs;
1681 } else {
1682 _inc_cset_recorded_rs_lengths = 0;
1683 }
1684 }
1685 _inc_cset_predicted_elapsed_time_ms +=
1686 _inc_cset_predicted_elapsed_time_ms_diffs;
1687
1688 _inc_cset_recorded_rs_lengths_diffs = 0;
1689 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1690 }
1691
1692 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1693 // This routine is used when:
1694 // * adding survivor regions to the incremental cset at the end of an
1695 // evacuation pause,
1696 // * adding the current allocation region to the incremental cset
1697 // when it is retired, and
1698 // * updating existing policy information for a region in the
1699 // incremental cset via young list RSet sampling.
1700 // Therefore this routine may be called at a safepoint by the
1701 // VM thread, or in-between safepoints by mutator threads (when
1702 // retiring the current allocation region) or a concurrent
1703 // refine thread (RSet sampling).
1704
1705 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1706 size_t used_bytes = hr->used();
1707 _inc_cset_recorded_rs_lengths += rs_length;
1708 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1709 _inc_cset_bytes_used_before += used_bytes;
1710
1711 // Cache the values we have added to the aggregated information
1712 // in the heap region in case we have to remove this region from
1713 // the incremental collection set, or it is updated by the
1714 // rset sampling code
1715 hr->set_recorded_rs_length(rs_length);
1716 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1717 }
1718
1719 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1720 size_t new_rs_length) {
1721 // Update the CSet information that is dependent on the new RS length
1722 assert(hr->is_young(), "Precondition");
1723 assert(!SafepointSynchronize::is_at_safepoint(),
1724 "should not be at a safepoint");
1725
1726 // We could have updated _inc_cset_recorded_rs_lengths and
1727 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1728 // that atomically, as this code is executed by a concurrent
1729 // refinement thread, potentially concurrently with a mutator thread
1730 // allocating a new region and also updating the same fields. To
1731 // avoid the atomic operations we accumulate these updates on two
1732 // separate fields (*_diffs) and we'll just add them to the "main"
1733 // fields at the start of a GC.
1734
1735 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1736 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1737 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1738
1739 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1740 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1741 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1742 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1743
1744 hr->set_recorded_rs_length(new_rs_length);
1745 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1746 }
1747
1748 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1749 assert(hr->is_young(), "invariant");
1750 assert(hr->young_index_in_cset() > -1, "should have already been set");
1751 assert(_inc_cset_build_state == Active, "Precondition");
1752
1753 // We need to clear and set the cached recorded/cached collection set
1754 // information in the heap region here (before the region gets added
1755 // to the collection set). An individual heap region's cached values
1756 // are calculated, aggregated with the policy collection set info,
1757 // and cached in the heap region here (initially) and (subsequently)
1758 // by the Young List sampling code.
1759
1760 size_t rs_length = hr->rem_set()->occupied();
1761 add_to_incremental_cset_info(hr, rs_length);
1762
1763 HeapWord* hr_end = hr->end();
1764 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1765
1766 assert(!hr->in_collection_set(), "invariant");
1767 hr->set_in_collection_set(true);
1768 assert( hr->next_in_collection_set() == NULL, "invariant");
1769
1770 _g1->register_region_with_in_cset_fast_test(hr);
1771 }
1772
1773 // Add the region at the RHS of the incremental cset
1774 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1775 // We should only ever be appending survivors at the end of a pause
1776 assert(hr->is_survivor(), "Logic");
1777
1778 // Do the 'common' stuff
1779 add_region_to_incremental_cset_common(hr);
1780
1781 // Now add the region at the right hand side
1782 if (_inc_cset_tail == NULL) {
1783 assert(_inc_cset_head == NULL, "invariant");
1784 _inc_cset_head = hr;
1785 } else {
1786 _inc_cset_tail->set_next_in_collection_set(hr);
1787 }
1788 _inc_cset_tail = hr;
1789 }
1790
1791 // Add the region to the LHS of the incremental cset
1792 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1793 // Survivors should be added to the RHS at the end of a pause
1794 assert(hr->is_eden(), "Logic");
1795
1796 // Do the 'common' stuff
1797 add_region_to_incremental_cset_common(hr);
1798
1799 // Add the region at the left hand side
1800 hr->set_next_in_collection_set(_inc_cset_head);
1801 if (_inc_cset_head == NULL) {
1802 assert(_inc_cset_tail == NULL, "Invariant");
1803 _inc_cset_tail = hr;
1804 }
1805 _inc_cset_head = hr;
1806 }
1807
1808 #ifndef PRODUCT
1809 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1810 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1811
1812 st->print_cr("\nCollection_set:");
1813 HeapRegion* csr = list_head;
1814 while (csr != NULL) {
1815 HeapRegion* next = csr->next_in_collection_set();
1816 assert(csr->in_collection_set(), "bad CS");
1817 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1818 HR_FORMAT_PARAMS(csr),
1819 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1820 csr->age_in_surv_rate_group_cond());
1821 csr = next;
1822 }
1823 }
1824 #endif // !PRODUCT
1825
1826 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1827 // Returns the given amount of reclaimable bytes (that represents
1828 // the amount of reclaimable space still to be collected) as a
1829 // percentage of the current heap capacity.
1830 size_t capacity_bytes = _g1->capacity();
1831 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1832 }
1833
1834 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1835 const char* false_action_str) {
1836 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1837 if (cset_chooser->is_empty()) {
1838 ergo_verbose0(ErgoMixedGCs,
1839 false_action_str,
1840 ergo_format_reason("candidate old regions not available"));
1841 return false;
1842 }
1843
1844 // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1845 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1846 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1847 double threshold = (double) G1HeapWastePercent;
1848 if (reclaimable_perc <= threshold) {
1849 ergo_verbose4(ErgoMixedGCs,
1850 false_action_str,
1851 ergo_format_reason("reclaimable percentage not over threshold")
1852 ergo_format_region("candidate old regions")
1853 ergo_format_byte_perc("reclaimable")
1854 ergo_format_perc("threshold"),
1855 cset_chooser->remaining_regions(),
1856 reclaimable_bytes,
1857 reclaimable_perc, threshold);
1858 return false;
1859 }
1860
1861 ergo_verbose4(ErgoMixedGCs,
1862 true_action_str,
1863 ergo_format_reason("candidate old regions available")
1864 ergo_format_region("candidate old regions")
1865 ergo_format_byte_perc("reclaimable")
1866 ergo_format_perc("threshold"),
1867 cset_chooser->remaining_regions(),
1868 reclaimable_bytes,
1869 reclaimable_perc, threshold);
1870 return true;
1871 }
1872
1873 uint G1CollectorPolicy::calc_min_old_cset_length() {
1874 // The min old CSet region bound is based on the maximum desired
1875 // number of mixed GCs after a cycle. I.e., even if some old regions
1876 // look expensive, we should add them to the CSet anyway to make
1877 // sure we go through the available old regions in no more than the
1878 // maximum desired number of mixed GCs.
1879 //
1880 // The calculation is based on the number of marked regions we added
1881 // to the CSet chooser in the first place, not how many remain, so
1882 // that the result is the same during all mixed GCs that follow a cycle.
1883
1884 const size_t region_num = (size_t) _collectionSetChooser->length();
1885 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1886 size_t result = region_num / gc_num;
1887 // emulate ceiling
1888 if (result * gc_num < region_num) {
1889 result += 1;
1890 }
1891 return (uint) result;
1892 }
1893
1894 uint G1CollectorPolicy::calc_max_old_cset_length() {
1895 // The max old CSet region bound is based on the threshold expressed
1896 // as a percentage of the heap size. I.e., it should bound the
1897 // number of old regions added to the CSet irrespective of how many
1898 // of them are available.
1899
1900 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1901 const size_t region_num = g1h->num_regions();
1902 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1903 size_t result = region_num * perc / 100;
1904 // emulate ceiling
1905 if (100 * result < region_num * perc) {
1906 result += 1;
1907 }
1908 return (uint) result;
1909 }
1910
1911
1912 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {
1913 double young_start_time_sec = os::elapsedTime();
1914
1915 YoungList* young_list = _g1->young_list();
1916 finalize_incremental_cset_building();
1917
1918 guarantee(target_pause_time_ms > 0.0,
1919 err_msg("target_pause_time_ms = %1.6lf should be positive",
1920 target_pause_time_ms));
1921 guarantee(_collection_set == NULL, "Precondition");
1922
1923 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1924 double predicted_pause_time_ms = base_time_ms;
1925 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1926
1927 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1928 "start choosing CSet",
1929 ergo_format_size("_pending_cards")
1930 ergo_format_ms("predicted base time")
1931 ergo_format_ms("remaining time")
1932 ergo_format_ms("target pause time"),
1933 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1934
1935 _last_gc_was_young = gcs_are_young() ? true : false;
1936
1937 if (_last_gc_was_young) {
1938 _trace_young_gen_time_data.increment_young_collection_count();
1939 } else {
1940 _trace_young_gen_time_data.increment_mixed_collection_count();
1941 }
1942
1943 // The young list is laid with the survivor regions from the previous
1944 // pause are appended to the RHS of the young list, i.e.
1945 // [Newly Young Regions ++ Survivors from last pause].
1946
1947 uint survivor_region_length = young_list->survivor_length();
1948 uint eden_region_length = young_list->length() - survivor_region_length;
1949 init_cset_region_lengths(eden_region_length, survivor_region_length);
1950
1951 HeapRegion* hr = young_list->first_survivor_region();
1952 while (hr != NULL) {
1953 assert(hr->is_survivor(), "badly formed young list");
1954 // There is a convention that all the young regions in the CSet
1955 // are tagged as "eden", so we do this for the survivors here. We
1956 // use the special set_eden_pre_gc() as it doesn't check that the
1957 // region is free (which is not the case here).
1958 hr->set_eden_pre_gc();
1959 hr = hr->get_next_young_region();
1960 }
1961
1962 // Clear the fields that point to the survivor list - they are all young now.
1963 young_list->clear_survivors();
1964
1965 _collection_set = _inc_cset_head;
1966 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1967 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1968 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1969
1970 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1971 "add young regions to CSet",
1972 ergo_format_region("eden")
1973 ergo_format_region("survivors")
1974 ergo_format_ms("predicted young region time"),
1975 eden_region_length, survivor_region_length,
1976 _inc_cset_predicted_elapsed_time_ms);
1977
1978 // The number of recorded young regions is the incremental
1979 // collection set's current size
1980 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1981
1982 double young_end_time_sec = os::elapsedTime();
1983 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1984
1985 // Set the start of the non-young choice time.
1986 double non_young_start_time_sec = young_end_time_sec;
1987
1988 if (!gcs_are_young()) {
1989 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1990 cset_chooser->verify();
1991 const uint min_old_cset_length = calc_min_old_cset_length();
1992 const uint max_old_cset_length = calc_max_old_cset_length();
1993
1994 uint expensive_region_num = 0;
1995 bool check_time_remaining = adaptive_young_list_length();
1996
1997 HeapRegion* hr = cset_chooser->peek();
1998 while (hr != NULL) {
1999 if (old_cset_region_length() >= max_old_cset_length) {
2000 // Added maximum number of old regions to the CSet.
2001 ergo_verbose2(ErgoCSetConstruction,
2002 "finish adding old regions to CSet",
2003 ergo_format_reason("old CSet region num reached max")
2004 ergo_format_region("old")
2005 ergo_format_region("max"),
2006 old_cset_region_length(), max_old_cset_length);
2007 break;
2008 }
2009
2010
2011 // Stop adding regions if the remaining reclaimable space is
2012 // not above G1HeapWastePercent.
2013 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2014 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2015 double threshold = (double) G1HeapWastePercent;
2016 if (reclaimable_perc <= threshold) {
2017 // We've added enough old regions that the amount of uncollected
2018 // reclaimable space is at or below the waste threshold. Stop
2019 // adding old regions to the CSet.
2020 ergo_verbose5(ErgoCSetConstruction,
2021 "finish adding old regions to CSet",
2022 ergo_format_reason("reclaimable percentage not over threshold")
2023 ergo_format_region("old")
2024 ergo_format_region("max")
2025 ergo_format_byte_perc("reclaimable")
2026 ergo_format_perc("threshold"),
2027 old_cset_region_length(),
2028 max_old_cset_length,
2029 reclaimable_bytes,
2030 reclaimable_perc, threshold);
2031 break;
2032 }
2033
2034 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
2035 if (check_time_remaining) {
2036 if (predicted_time_ms > time_remaining_ms) {
2037 // Too expensive for the current CSet.
2038
2039 if (old_cset_region_length() >= min_old_cset_length) {
2040 // We have added the minimum number of old regions to the CSet,
2041 // we are done with this CSet.
2042 ergo_verbose4(ErgoCSetConstruction,
2043 "finish adding old regions to CSet",
2044 ergo_format_reason("predicted time is too high")
2045 ergo_format_ms("predicted time")
2046 ergo_format_ms("remaining time")
2047 ergo_format_region("old")
2048 ergo_format_region("min"),
2049 predicted_time_ms, time_remaining_ms,
2050 old_cset_region_length(), min_old_cset_length);
2051 break;
2052 }
2053
2054 // We'll add it anyway given that we haven't reached the
2055 // minimum number of old regions.
2056 expensive_region_num += 1;
2057 }
2058 } else {
2059 if (old_cset_region_length() >= min_old_cset_length) {
2060 // In the non-auto-tuning case, we'll finish adding regions
2061 // to the CSet if we reach the minimum.
2062 ergo_verbose2(ErgoCSetConstruction,
2063 "finish adding old regions to CSet",
2064 ergo_format_reason("old CSet region num reached min")
2065 ergo_format_region("old")
2066 ergo_format_region("min"),
2067 old_cset_region_length(), min_old_cset_length);
2068 break;
2069 }
2070 }
2071
2072 // We will add this region to the CSet.
2073 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2074 predicted_pause_time_ms += predicted_time_ms;
2075 cset_chooser->remove_and_move_to_next(hr);
2076 _g1->old_set_remove(hr);
2077 add_old_region_to_cset(hr);
2078
2079 hr = cset_chooser->peek();
2080 }
2081 if (hr == NULL) {
2082 ergo_verbose0(ErgoCSetConstruction,
2083 "finish adding old regions to CSet",
2084 ergo_format_reason("candidate old regions not available"));
2085 }
2086
2087 if (expensive_region_num > 0) {
2088 // We print the information once here at the end, predicated on
2089 // whether we added any apparently expensive regions or not, to
2090 // avoid generating output per region.
2091 ergo_verbose4(ErgoCSetConstruction,
2092 "added expensive regions to CSet",
2093 ergo_format_reason("old CSet region num not reached min")
2094 ergo_format_region("old")
2095 ergo_format_region("expensive")
2096 ergo_format_region("min")
2097 ergo_format_ms("remaining time"),
2098 old_cset_region_length(),
2099 expensive_region_num,
2100 min_old_cset_length,
2101 time_remaining_ms);
2102 }
2103
2104 cset_chooser->verify();
2105 }
2106
2107 stop_incremental_cset_building();
2108
2109 ergo_verbose5(ErgoCSetConstruction,
2110 "finish choosing CSet",
2111 ergo_format_region("eden")
2112 ergo_format_region("survivors")
2113 ergo_format_region("old")
2114 ergo_format_ms("predicted pause time")
2115 ergo_format_ms("target pause time"),
2116 eden_region_length, survivor_region_length,
2117 old_cset_region_length(),
2118 predicted_pause_time_ms, target_pause_time_ms);
2119
2120 double non_young_end_time_sec = os::elapsedTime();
2121 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2122 evacuation_info.set_collectionset_regions(cset_region_length());
2123 }
2124
2125 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2126 if(TraceYoungGenTime) {
2127 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2128 }
2129 }
2130
2131 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2132 if(TraceYoungGenTime) {
2133 _all_yield_times_ms.add(yield_time_ms);
2134 }
2135 }
2136
2137 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2138 if(TraceYoungGenTime) {
2139 _total.add(pause_time_ms);
2140 _other.add(pause_time_ms - phase_times->accounted_time_ms());
2141 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2142 _parallel.add(phase_times->cur_collection_par_time_ms());
2143 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2144 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2145 _update_rs.add(phase_times->average_last_update_rs_time());
2146 _scan_rs.add(phase_times->average_last_scan_rs_time());
2147 _obj_copy.add(phase_times->average_last_obj_copy_time());
2148 _termination.add(phase_times->average_last_termination_time());
2149
2150 double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2151 phase_times->average_last_satb_filtering_times_ms() +
2152 phase_times->average_last_update_rs_time() +
2153 phase_times->average_last_scan_rs_time() +
2154 phase_times->average_last_obj_copy_time() +
2155 + phase_times->average_last_termination_time();
2156
2157 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2158 _parallel_other.add(parallel_other_time);
2159 _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2160 }
2161 }
2162
2163 void TraceYoungGenTimeData::increment_young_collection_count() {
2164 if(TraceYoungGenTime) {
2165 ++_young_pause_num;
2166 }
2167 }
2168
2169 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2170 if(TraceYoungGenTime) {
2171 ++_mixed_pause_num;
2172 }
2173 }
2174
2175 void TraceYoungGenTimeData::print_summary(const char* str,
2176 const NumberSeq* seq) const {
2177 double sum = seq->sum();
2178 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2179 str, sum / 1000.0, seq->avg());
2180 }
2181
2182 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2183 const NumberSeq* seq) const {
2184 print_summary(str, seq);
2185 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2186 "(num", seq->num(), seq->sd(), seq->maximum());
2187 }
2188
2189 void TraceYoungGenTimeData::print() const {
2190 if (!TraceYoungGenTime) {
2191 return;
2192 }
2193
2194 gclog_or_tty->print_cr("ALL PAUSES");
2195 print_summary_sd(" Total", &_total);
2196 gclog_or_tty->cr();
2197 gclog_or_tty->cr();
2198 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2199 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2200 gclog_or_tty->cr();
2201
2202 gclog_or_tty->print_cr("EVACUATION PAUSES");
2203
2204 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2205 gclog_or_tty->print_cr("none");
2206 } else {
2207 print_summary_sd(" Evacuation Pauses", &_total);
2208 print_summary(" Root Region Scan Wait", &_root_region_scan_wait);
2209 print_summary(" Parallel Time", &_parallel);
2210 print_summary(" Ext Root Scanning", &_ext_root_scan);
2211 print_summary(" SATB Filtering", &_satb_filtering);
2212 print_summary(" Update RS", &_update_rs);
2213 print_summary(" Scan RS", &_scan_rs);
2214 print_summary(" Object Copy", &_obj_copy);
2215 print_summary(" Termination", &_termination);
2216 print_summary(" Parallel Other", &_parallel_other);
2217 print_summary(" Clear CT", &_clear_ct);
2218 print_summary(" Other", &_other);
2219 }
2220 gclog_or_tty->cr();
2221
2222 gclog_or_tty->print_cr("MISC");
2223 print_summary_sd(" Stop World", &_all_stop_world_times_ms);
2224 print_summary_sd(" Yields", &_all_yield_times_ms);
2225 }
2226
2227 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2228 if (TraceOldGenTime) {
2229 _all_full_gc_times.add(full_gc_time_ms);
2230 }
2231 }
2232
2233 void TraceOldGenTimeData::print() const {
2234 if (!TraceOldGenTime) {
2235 return;
2236 }
2237
2238 if (_all_full_gc_times.num() > 0) {
2239 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2240 _all_full_gc_times.num(),
2241 _all_full_gc_times.sum() / 1000.0);
2242 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2243 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2244 _all_full_gc_times.sd(),
2245 _all_full_gc_times.maximum());
2246 }
2247 }