Mon, 12 Mar 2012 14:59:00 -0700
7147724: G1: hang in SurrogateLockerThread::manipulatePLL
Summary: Attempting to initiate a marking cycle when allocating a humongous object can, if a marking cycle is successfully initiated by another thread, result in the allocating thread spinning until the marking cycle is complete. Eliminate a deadlock between the main ConcurrentMarkThread, the SurrogateLocker thread, the VM thread, and a mutator thread waiting on the SecondaryFreeList_lock (while free regions are going to become available) by not manipulating the pending list lock during the prologue and epilogue of the cleanup pause.
Reviewed-by: brutisso, jcoomes, tonyp
1 /*
2 * Copyright (c) 2001, 2012, 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 */
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/heapRegionRemSet.hpp"
33 #include "gc_implementation/shared/gcPolicyCounters.hpp"
34 #include "runtime/arguments.hpp"
35 #include "runtime/java.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "utilities/debug.hpp"
39 // Different defaults for different number of GC threads
40 // They were chosen by running GCOld and SPECjbb on debris with different
41 // numbers of GC threads and choosing them based on the results
43 // all the same
44 static double rs_length_diff_defaults[] = {
45 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
46 };
48 static double cost_per_card_ms_defaults[] = {
49 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
50 };
52 // all the same
53 static double young_cards_per_entry_ratio_defaults[] = {
54 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
55 };
57 static double cost_per_entry_ms_defaults[] = {
58 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
59 };
61 static double cost_per_byte_ms_defaults[] = {
62 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
63 };
65 // these should be pretty consistent
66 static double constant_other_time_ms_defaults[] = {
67 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
68 };
71 static double young_other_cost_per_region_ms_defaults[] = {
72 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
73 };
75 static double non_young_other_cost_per_region_ms_defaults[] = {
76 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
77 };
79 // Help class for avoiding interleaved logging
80 class LineBuffer: public StackObj {
82 private:
83 static const int BUFFER_LEN = 1024;
84 static const int INDENT_CHARS = 3;
85 char _buffer[BUFFER_LEN];
86 int _indent_level;
87 int _cur;
89 void vappend(const char* format, va_list ap) {
90 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
91 if (res != -1) {
92 _cur += res;
93 } else {
94 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
95 _buffer[BUFFER_LEN -1] = 0;
96 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
97 }
98 }
100 public:
101 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
102 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
103 _buffer[_cur] = ' ';
104 }
105 }
107 #ifndef PRODUCT
108 ~LineBuffer() {
109 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
110 }
111 #endif
113 void append(const char* format, ...) {
114 va_list ap;
115 va_start(ap, format);
116 vappend(format, ap);
117 va_end(ap);
118 }
120 void append_and_print_cr(const char* format, ...) {
121 va_list ap;
122 va_start(ap, format);
123 vappend(format, ap);
124 va_end(ap);
125 gclog_or_tty->print_cr("%s", _buffer);
126 _cur = _indent_level * INDENT_CHARS;
127 }
128 };
130 G1CollectorPolicy::G1CollectorPolicy() :
131 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
132 ? ParallelGCThreads : 1),
134 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
135 _all_pause_times_ms(new NumberSeq()),
136 _stop_world_start(0.0),
137 _all_stop_world_times_ms(new NumberSeq()),
138 _all_yield_times_ms(new NumberSeq()),
140 _summary(new Summary()),
142 _cur_clear_ct_time_ms(0.0),
143 _mark_closure_time_ms(0.0),
144 _root_region_scan_wait_time_ms(0.0),
146 _cur_ref_proc_time_ms(0.0),
147 _cur_ref_enq_time_ms(0.0),
149 #ifndef PRODUCT
150 _min_clear_cc_time_ms(-1.0),
151 _max_clear_cc_time_ms(-1.0),
152 _cur_clear_cc_time_ms(0.0),
153 _cum_clear_cc_time_ms(0.0),
154 _num_cc_clears(0L),
155 #endif
157 _aux_num(10),
158 _all_aux_times_ms(new NumberSeq[_aux_num]),
159 _cur_aux_start_times_ms(new double[_aux_num]),
160 _cur_aux_times_ms(new double[_aux_num]),
161 _cur_aux_times_set(new bool[_aux_num]),
163 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
164 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
166 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
167 _prev_collection_pause_end_ms(0.0),
168 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
169 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
170 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
171 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
172 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
173 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
174 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
175 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
176 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
177 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
178 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
179 _non_young_other_cost_per_region_ms_seq(
180 new TruncatedSeq(TruncatedSeqLength)),
182 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
183 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
185 _pause_time_target_ms((double) MaxGCPauseMillis),
187 _gcs_are_young(true),
188 _young_pause_num(0),
189 _mixed_pause_num(0),
191 _during_marking(false),
192 _in_marking_window(false),
193 _in_marking_window_im(false),
195 _known_garbage_ratio(0.0),
196 _known_garbage_bytes(0),
198 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
200 _recent_prev_end_times_for_all_gcs_sec(
201 new TruncatedSeq(NumPrevPausesForHeuristics)),
203 _recent_avg_pause_time_ratio(0.0),
205 _all_full_gc_times_ms(new NumberSeq()),
207 _initiate_conc_mark_if_possible(false),
208 _during_initial_mark_pause(false),
209 _last_young_gc(false),
210 _last_gc_was_young(false),
212 _eden_bytes_before_gc(0),
213 _survivor_bytes_before_gc(0),
214 _capacity_before_gc(0),
216 _eden_cset_region_length(0),
217 _survivor_cset_region_length(0),
218 _old_cset_region_length(0),
220 _collection_set(NULL),
221 _collection_set_bytes_used_before(0),
223 // Incremental CSet attributes
224 _inc_cset_build_state(Inactive),
225 _inc_cset_head(NULL),
226 _inc_cset_tail(NULL),
227 _inc_cset_bytes_used_before(0),
228 _inc_cset_max_finger(NULL),
229 _inc_cset_recorded_rs_lengths(0),
230 _inc_cset_recorded_rs_lengths_diffs(0),
231 _inc_cset_predicted_elapsed_time_ms(0.0),
232 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
234 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
235 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
236 #endif // _MSC_VER
238 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
239 G1YoungSurvRateNumRegionsSummary)),
240 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
241 G1YoungSurvRateNumRegionsSummary)),
242 // add here any more surv rate groups
243 _recorded_survivor_regions(0),
244 _recorded_survivor_head(NULL),
245 _recorded_survivor_tail(NULL),
246 _survivors_age_table(true),
248 _gc_overhead_perc(0.0) {
250 // Set up the region size and associated fields. Given that the
251 // policy is created before the heap, we have to set this up here,
252 // so it's done as soon as possible.
253 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
254 HeapRegionRemSet::setup_remset_size();
256 G1ErgoVerbose::initialize();
257 if (PrintAdaptiveSizePolicy) {
258 // Currently, we only use a single switch for all the heuristics.
259 G1ErgoVerbose::set_enabled(true);
260 // Given that we don't currently have a verboseness level
261 // parameter, we'll hardcode this to high. This can be easily
262 // changed in the future.
263 G1ErgoVerbose::set_level(ErgoHigh);
264 } else {
265 G1ErgoVerbose::set_enabled(false);
266 }
268 // Verify PLAB sizes
269 const size_t region_size = HeapRegion::GrainWords;
270 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
271 char buffer[128];
272 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
273 OldPLABSize > region_size ? "Old" : "Young", region_size);
274 vm_exit_during_initialization(buffer);
275 }
277 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
278 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
280 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
281 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
282 _par_last_satb_filtering_times_ms = new double[_parallel_gc_threads];
284 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
285 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
287 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
289 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
291 _par_last_termination_times_ms = new double[_parallel_gc_threads];
292 _par_last_termination_attempts = new double[_parallel_gc_threads];
293 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
294 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
295 _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
297 int index;
298 if (ParallelGCThreads == 0)
299 index = 0;
300 else if (ParallelGCThreads > 8)
301 index = 7;
302 else
303 index = ParallelGCThreads - 1;
305 _pending_card_diff_seq->add(0.0);
306 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
307 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
308 _young_cards_per_entry_ratio_seq->add(
309 young_cards_per_entry_ratio_defaults[index]);
310 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
311 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
312 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
313 _young_other_cost_per_region_ms_seq->add(
314 young_other_cost_per_region_ms_defaults[index]);
315 _non_young_other_cost_per_region_ms_seq->add(
316 non_young_other_cost_per_region_ms_defaults[index]);
318 // Below, we might need to calculate the pause time target based on
319 // the pause interval. When we do so we are going to give G1 maximum
320 // flexibility and allow it to do pauses when it needs to. So, we'll
321 // arrange that the pause interval to be pause time target + 1 to
322 // ensure that a) the pause time target is maximized with respect to
323 // the pause interval and b) we maintain the invariant that pause
324 // time target < pause interval. If the user does not want this
325 // maximum flexibility, they will have to set the pause interval
326 // explicitly.
328 // First make sure that, if either parameter is set, its value is
329 // reasonable.
330 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
331 if (MaxGCPauseMillis < 1) {
332 vm_exit_during_initialization("MaxGCPauseMillis should be "
333 "greater than 0");
334 }
335 }
336 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
337 if (GCPauseIntervalMillis < 1) {
338 vm_exit_during_initialization("GCPauseIntervalMillis should be "
339 "greater than 0");
340 }
341 }
343 // Then, if the pause time target parameter was not set, set it to
344 // the default value.
345 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
346 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
347 // The default pause time target in G1 is 200ms
348 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
349 } else {
350 // We do not allow the pause interval to be set without the
351 // pause time target
352 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
353 "without setting MaxGCPauseMillis");
354 }
355 }
357 // Then, if the interval parameter was not set, set it according to
358 // the pause time target (this will also deal with the case when the
359 // pause time target is the default value).
360 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
361 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
362 }
364 // Finally, make sure that the two parameters are consistent.
365 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
366 char buffer[256];
367 jio_snprintf(buffer, 256,
368 "MaxGCPauseMillis (%u) should be less than "
369 "GCPauseIntervalMillis (%u)",
370 MaxGCPauseMillis, GCPauseIntervalMillis);
371 vm_exit_during_initialization(buffer);
372 }
374 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
375 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
376 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
377 _sigma = (double) G1ConfidencePercent / 100.0;
379 // start conservatively (around 50ms is about right)
380 _concurrent_mark_remark_times_ms->add(0.05);
381 _concurrent_mark_cleanup_times_ms->add(0.20);
382 _tenuring_threshold = MaxTenuringThreshold;
383 // _max_survivor_regions will be calculated by
384 // update_young_list_target_length() during initialization.
385 _max_survivor_regions = 0;
387 assert(GCTimeRatio > 0,
388 "we should have set it to a default value set_g1_gc_flags() "
389 "if a user set it to 0");
390 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
392 uintx reserve_perc = G1ReservePercent;
393 // Put an artificial ceiling on this so that it's not set to a silly value.
394 if (reserve_perc > 50) {
395 reserve_perc = 50;
396 warning("G1ReservePercent is set to a value that is too large, "
397 "it's been updated to %u", reserve_perc);
398 }
399 _reserve_factor = (double) reserve_perc / 100.0;
400 // This will be set when the heap is expanded
401 // for the first time during initialization.
402 _reserve_regions = 0;
404 initialize_all();
405 _collectionSetChooser = new CollectionSetChooser();
406 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
407 }
409 void G1CollectorPolicy::initialize_flags() {
410 set_min_alignment(HeapRegion::GrainBytes);
411 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
412 if (SurvivorRatio < 1) {
413 vm_exit_during_initialization("Invalid survivor ratio specified");
414 }
415 CollectorPolicy::initialize_flags();
416 }
418 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
419 assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");
420 assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");
421 assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");
423 if (FLAG_IS_CMDLINE(NewRatio)) {
424 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
425 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
426 } else {
427 _sizer_kind = SizerNewRatio;
428 _adaptive_size = false;
429 return;
430 }
431 }
433 if (FLAG_IS_CMDLINE(NewSize)) {
434 _min_desired_young_length = MAX2((size_t) 1, NewSize / HeapRegion::GrainBytes);
435 if (FLAG_IS_CMDLINE(MaxNewSize)) {
436 _max_desired_young_length = MAX2((size_t) 1, MaxNewSize / HeapRegion::GrainBytes);
437 _sizer_kind = SizerMaxAndNewSize;
438 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
439 } else {
440 _sizer_kind = SizerNewSizeOnly;
441 }
442 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
443 _max_desired_young_length = MAX2((size_t) 1, MaxNewSize / HeapRegion::GrainBytes);
444 _sizer_kind = SizerMaxNewSizeOnly;
445 }
446 }
448 size_t G1YoungGenSizer::calculate_default_min_length(size_t new_number_of_heap_regions) {
449 size_t default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;
450 return MAX2((size_t)1, default_value);
451 }
453 size_t G1YoungGenSizer::calculate_default_max_length(size_t new_number_of_heap_regions) {
454 size_t default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;
455 return MAX2((size_t)1, default_value);
456 }
458 void G1YoungGenSizer::heap_size_changed(size_t new_number_of_heap_regions) {
459 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
461 switch (_sizer_kind) {
462 case SizerDefaults:
463 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
464 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
465 break;
466 case SizerNewSizeOnly:
467 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
468 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
469 break;
470 case SizerMaxNewSizeOnly:
471 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
472 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
473 break;
474 case SizerMaxAndNewSize:
475 // Do nothing. Values set on the command line, don't update them at runtime.
476 break;
477 case SizerNewRatio:
478 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
479 _max_desired_young_length = _min_desired_young_length;
480 break;
481 default:
482 ShouldNotReachHere();
483 }
485 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
486 }
488 void G1CollectorPolicy::init() {
489 // Set aside an initial future to_space.
490 _g1 = G1CollectedHeap::heap();
492 assert(Heap_lock->owned_by_self(), "Locking discipline.");
494 initialize_gc_policy_counters();
496 if (adaptive_young_list_length()) {
497 _young_list_fixed_length = 0;
498 } else {
499 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
500 }
501 _free_regions_at_end_of_collection = _g1->free_regions();
502 update_young_list_target_length();
503 _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
505 // We may immediately start allocating regions and placing them on the
506 // collection set list. Initialize the per-collection set info
507 start_incremental_cset_building();
508 }
510 // Create the jstat counters for the policy.
511 void G1CollectorPolicy::initialize_gc_policy_counters() {
512 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
513 }
515 bool G1CollectorPolicy::predict_will_fit(size_t young_length,
516 double base_time_ms,
517 size_t base_free_regions,
518 double target_pause_time_ms) {
519 if (young_length >= base_free_regions) {
520 // end condition 1: not enough space for the young regions
521 return false;
522 }
524 double accum_surv_rate = accum_yg_surv_rate_pred((int)(young_length - 1));
525 size_t bytes_to_copy =
526 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
527 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
528 double young_other_time_ms = predict_young_other_time_ms(young_length);
529 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
530 if (pause_time_ms > target_pause_time_ms) {
531 // end condition 2: prediction is over the target pause time
532 return false;
533 }
535 size_t free_bytes =
536 (base_free_regions - young_length) * HeapRegion::GrainBytes;
537 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
538 // end condition 3: out-of-space (conservatively!)
539 return false;
540 }
542 // success!
543 return true;
544 }
546 void G1CollectorPolicy::record_new_heap_size(size_t new_number_of_regions) {
547 // re-calculate the necessary reserve
548 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
549 // We use ceiling so that if reserve_regions_d is > 0.0 (but
550 // smaller than 1.0) we'll get 1.
551 _reserve_regions = (size_t) ceil(reserve_regions_d);
553 _young_gen_sizer->heap_size_changed(new_number_of_regions);
554 }
556 size_t G1CollectorPolicy::calculate_young_list_desired_min_length(
557 size_t base_min_length) {
558 size_t desired_min_length = 0;
559 if (adaptive_young_list_length()) {
560 if (_alloc_rate_ms_seq->num() > 3) {
561 double now_sec = os::elapsedTime();
562 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
563 double alloc_rate_ms = predict_alloc_rate_ms();
564 desired_min_length = (size_t) ceil(alloc_rate_ms * when_ms);
565 } else {
566 // otherwise we don't have enough info to make the prediction
567 }
568 }
569 desired_min_length += base_min_length;
570 // make sure we don't go below any user-defined minimum bound
571 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
572 }
574 size_t G1CollectorPolicy::calculate_young_list_desired_max_length() {
575 // Here, we might want to also take into account any additional
576 // constraints (i.e., user-defined minimum bound). Currently, we
577 // effectively don't set this bound.
578 return _young_gen_sizer->max_desired_young_length();
579 }
581 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
582 if (rs_lengths == (size_t) -1) {
583 // if it's set to the default value (-1), we should predict it;
584 // otherwise, use the given value.
585 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
586 }
588 // Calculate the absolute and desired min bounds.
590 // This is how many young regions we already have (currently: the survivors).
591 size_t base_min_length = recorded_survivor_regions();
592 // This is the absolute minimum young length, which ensures that we
593 // can allocate one eden region in the worst-case.
594 size_t absolute_min_length = base_min_length + 1;
595 size_t desired_min_length =
596 calculate_young_list_desired_min_length(base_min_length);
597 if (desired_min_length < absolute_min_length) {
598 desired_min_length = absolute_min_length;
599 }
601 // Calculate the absolute and desired max bounds.
603 // We will try our best not to "eat" into the reserve.
604 size_t absolute_max_length = 0;
605 if (_free_regions_at_end_of_collection > _reserve_regions) {
606 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
607 }
608 size_t desired_max_length = calculate_young_list_desired_max_length();
609 if (desired_max_length > absolute_max_length) {
610 desired_max_length = absolute_max_length;
611 }
613 size_t young_list_target_length = 0;
614 if (adaptive_young_list_length()) {
615 if (gcs_are_young()) {
616 young_list_target_length =
617 calculate_young_list_target_length(rs_lengths,
618 base_min_length,
619 desired_min_length,
620 desired_max_length);
621 _rs_lengths_prediction = rs_lengths;
622 } else {
623 // Don't calculate anything and let the code below bound it to
624 // the desired_min_length, i.e., do the next GC as soon as
625 // possible to maximize how many old regions we can add to it.
626 }
627 } else {
628 // The user asked for a fixed young gen so we'll fix the young gen
629 // whether the next GC is young or mixed.
630 young_list_target_length = _young_list_fixed_length;
631 }
633 // Make sure we don't go over the desired max length, nor under the
634 // desired min length. In case they clash, desired_min_length wins
635 // which is why that test is second.
636 if (young_list_target_length > desired_max_length) {
637 young_list_target_length = desired_max_length;
638 }
639 if (young_list_target_length < desired_min_length) {
640 young_list_target_length = desired_min_length;
641 }
643 assert(young_list_target_length > recorded_survivor_regions(),
644 "we should be able to allocate at least one eden region");
645 assert(young_list_target_length >= absolute_min_length, "post-condition");
646 _young_list_target_length = young_list_target_length;
648 update_max_gc_locker_expansion();
649 }
651 size_t
652 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
653 size_t base_min_length,
654 size_t desired_min_length,
655 size_t desired_max_length) {
656 assert(adaptive_young_list_length(), "pre-condition");
657 assert(gcs_are_young(), "only call this for young GCs");
659 // In case some edge-condition makes the desired max length too small...
660 if (desired_max_length <= desired_min_length) {
661 return desired_min_length;
662 }
664 // We'll adjust min_young_length and max_young_length not to include
665 // the already allocated young regions (i.e., so they reflect the
666 // min and max eden regions we'll allocate). The base_min_length
667 // will be reflected in the predictions by the
668 // survivor_regions_evac_time prediction.
669 assert(desired_min_length > base_min_length, "invariant");
670 size_t min_young_length = desired_min_length - base_min_length;
671 assert(desired_max_length > base_min_length, "invariant");
672 size_t max_young_length = desired_max_length - base_min_length;
674 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
675 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
676 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
677 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
678 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
679 double base_time_ms =
680 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
681 survivor_regions_evac_time;
682 size_t available_free_regions = _free_regions_at_end_of_collection;
683 size_t base_free_regions = 0;
684 if (available_free_regions > _reserve_regions) {
685 base_free_regions = available_free_regions - _reserve_regions;
686 }
688 // Here, we will make sure that the shortest young length that
689 // makes sense fits within the target pause time.
691 if (predict_will_fit(min_young_length, base_time_ms,
692 base_free_regions, target_pause_time_ms)) {
693 // The shortest young length will fit into the target pause time;
694 // we'll now check whether the absolute maximum number of young
695 // regions will fit in the target pause time. If not, we'll do
696 // a binary search between min_young_length and max_young_length.
697 if (predict_will_fit(max_young_length, base_time_ms,
698 base_free_regions, target_pause_time_ms)) {
699 // The maximum young length will fit into the target pause time.
700 // We are done so set min young length to the maximum length (as
701 // the result is assumed to be returned in min_young_length).
702 min_young_length = max_young_length;
703 } else {
704 // The maximum possible number of young regions will not fit within
705 // the target pause time so we'll search for the optimal
706 // length. The loop invariants are:
707 //
708 // min_young_length < max_young_length
709 // min_young_length is known to fit into the target pause time
710 // max_young_length is known not to fit into the target pause time
711 //
712 // Going into the loop we know the above hold as we've just
713 // checked them. Every time around the loop we check whether
714 // the middle value between min_young_length and
715 // max_young_length fits into the target pause time. If it
716 // does, it becomes the new min. If it doesn't, it becomes
717 // the new max. This way we maintain the loop invariants.
719 assert(min_young_length < max_young_length, "invariant");
720 size_t diff = (max_young_length - min_young_length) / 2;
721 while (diff > 0) {
722 size_t young_length = min_young_length + diff;
723 if (predict_will_fit(young_length, base_time_ms,
724 base_free_regions, target_pause_time_ms)) {
725 min_young_length = young_length;
726 } else {
727 max_young_length = young_length;
728 }
729 assert(min_young_length < max_young_length, "invariant");
730 diff = (max_young_length - min_young_length) / 2;
731 }
732 // The results is min_young_length which, according to the
733 // loop invariants, should fit within the target pause time.
735 // These are the post-conditions of the binary search above:
736 assert(min_young_length < max_young_length,
737 "otherwise we should have discovered that max_young_length "
738 "fits into the pause target and not done the binary search");
739 assert(predict_will_fit(min_young_length, base_time_ms,
740 base_free_regions, target_pause_time_ms),
741 "min_young_length, the result of the binary search, should "
742 "fit into the pause target");
743 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
744 base_free_regions, target_pause_time_ms),
745 "min_young_length, the result of the binary search, should be "
746 "optimal, so no larger length should fit into the pause target");
747 }
748 } else {
749 // Even the minimum length doesn't fit into the pause time
750 // target, return it as the result nevertheless.
751 }
752 return base_min_length + min_young_length;
753 }
755 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
756 double survivor_regions_evac_time = 0.0;
757 for (HeapRegion * r = _recorded_survivor_head;
758 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
759 r = r->get_next_young_region()) {
760 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
761 }
762 return survivor_regions_evac_time;
763 }
765 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
766 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
768 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
769 if (rs_lengths > _rs_lengths_prediction) {
770 // add 10% to avoid having to recalculate often
771 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
772 update_young_list_target_length(rs_lengths_prediction);
773 }
774 }
778 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
779 bool is_tlab,
780 bool* gc_overhead_limit_was_exceeded) {
781 guarantee(false, "Not using this policy feature yet.");
782 return NULL;
783 }
785 // This method controls how a collector handles one or more
786 // of its generations being fully allocated.
787 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
788 bool is_tlab) {
789 guarantee(false, "Not using this policy feature yet.");
790 return NULL;
791 }
794 #ifndef PRODUCT
795 bool G1CollectorPolicy::verify_young_ages() {
796 HeapRegion* head = _g1->young_list()->first_region();
797 return
798 verify_young_ages(head, _short_lived_surv_rate_group);
799 // also call verify_young_ages on any additional surv rate groups
800 }
802 bool
803 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
804 SurvRateGroup *surv_rate_group) {
805 guarantee( surv_rate_group != NULL, "pre-condition" );
807 const char* name = surv_rate_group->name();
808 bool ret = true;
809 int prev_age = -1;
811 for (HeapRegion* curr = head;
812 curr != NULL;
813 curr = curr->get_next_young_region()) {
814 SurvRateGroup* group = curr->surv_rate_group();
815 if (group == NULL && !curr->is_survivor()) {
816 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
817 ret = false;
818 }
820 if (surv_rate_group == group) {
821 int age = curr->age_in_surv_rate_group();
823 if (age < 0) {
824 gclog_or_tty->print_cr("## %s: encountered negative age", name);
825 ret = false;
826 }
828 if (age <= prev_age) {
829 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
830 "(%d, %d)", name, age, prev_age);
831 ret = false;
832 }
833 prev_age = age;
834 }
835 }
837 return ret;
838 }
839 #endif // PRODUCT
841 void G1CollectorPolicy::record_full_collection_start() {
842 _cur_collection_start_sec = os::elapsedTime();
843 // Release the future to-space so that it is available for compaction into.
844 _g1->set_full_collection();
845 }
847 void G1CollectorPolicy::record_full_collection_end() {
848 // Consider this like a collection pause for the purposes of allocation
849 // since last pause.
850 double end_sec = os::elapsedTime();
851 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
852 double full_gc_time_ms = full_gc_time_sec * 1000.0;
854 _all_full_gc_times_ms->add(full_gc_time_ms);
856 update_recent_gc_times(end_sec, full_gc_time_ms);
858 _g1->clear_full_collection();
860 // "Nuke" the heuristics that control the young/mixed GC
861 // transitions and make sure we start with young GCs after the Full GC.
862 set_gcs_are_young(true);
863 _last_young_gc = false;
864 clear_initiate_conc_mark_if_possible();
865 clear_during_initial_mark_pause();
866 _known_garbage_bytes = 0;
867 _known_garbage_ratio = 0.0;
868 _in_marking_window = false;
869 _in_marking_window_im = false;
871 _short_lived_surv_rate_group->start_adding_regions();
872 // also call this on any additional surv rate groups
874 record_survivor_regions(0, NULL, NULL);
876 _free_regions_at_end_of_collection = _g1->free_regions();
877 // Reset survivors SurvRateGroup.
878 _survivor_surv_rate_group->reset();
879 update_young_list_target_length();
880 _collectionSetChooser->clearMarkedHeapRegions();
881 }
883 void G1CollectorPolicy::record_stop_world_start() {
884 _stop_world_start = os::elapsedTime();
885 }
887 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
888 size_t start_used) {
889 if (PrintGCDetails) {
890 gclog_or_tty->stamp(PrintGCTimeStamps);
891 gclog_or_tty->print("[GC pause");
892 gclog_or_tty->print(" (%s)", gcs_are_young() ? "young" : "mixed");
893 }
895 // We only need to do this here as the policy will only be applied
896 // to the GC we're about to start. so, no point is calculating this
897 // every time we calculate / recalculate the target young length.
898 update_survivors_policy();
900 assert(_g1->used() == _g1->recalculate_used(),
901 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
902 _g1->used(), _g1->recalculate_used()));
904 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
905 _all_stop_world_times_ms->add(s_w_t_ms);
906 _stop_world_start = 0.0;
908 _cur_collection_start_sec = start_time_sec;
909 _cur_collection_pause_used_at_start_bytes = start_used;
910 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
911 _pending_cards = _g1->pending_card_num();
912 _max_pending_cards = _g1->max_pending_card_num();
914 _bytes_in_collection_set_before_gc = 0;
915 _bytes_copied_during_gc = 0;
917 YoungList* young_list = _g1->young_list();
918 _eden_bytes_before_gc = young_list->eden_used_bytes();
919 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
920 _capacity_before_gc = _g1->capacity();
922 #ifdef DEBUG
923 // initialise these to something well known so that we can spot
924 // if they are not set properly
926 for (int i = 0; i < _parallel_gc_threads; ++i) {
927 _par_last_gc_worker_start_times_ms[i] = -1234.0;
928 _par_last_ext_root_scan_times_ms[i] = -1234.0;
929 _par_last_satb_filtering_times_ms[i] = -1234.0;
930 _par_last_update_rs_times_ms[i] = -1234.0;
931 _par_last_update_rs_processed_buffers[i] = -1234.0;
932 _par_last_scan_rs_times_ms[i] = -1234.0;
933 _par_last_obj_copy_times_ms[i] = -1234.0;
934 _par_last_termination_times_ms[i] = -1234.0;
935 _par_last_termination_attempts[i] = -1234.0;
936 _par_last_gc_worker_end_times_ms[i] = -1234.0;
937 _par_last_gc_worker_times_ms[i] = -1234.0;
938 _par_last_gc_worker_other_times_ms[i] = -1234.0;
939 }
940 #endif
942 for (int i = 0; i < _aux_num; ++i) {
943 _cur_aux_times_ms[i] = 0.0;
944 _cur_aux_times_set[i] = false;
945 }
947 // This is initialized to zero here and is set during
948 // the evacuation pause if marking is in progress.
949 _cur_satb_drain_time_ms = 0.0;
950 // This is initialized to zero here and is set during the evacuation
951 // pause if we actually waited for the root region scanning to finish.
952 _root_region_scan_wait_time_ms = 0.0;
954 _last_gc_was_young = false;
956 // do that for any other surv rate groups
957 _short_lived_surv_rate_group->stop_adding_regions();
958 _survivors_age_table.clear();
960 assert( verify_young_ages(), "region age verification" );
961 }
963 void G1CollectorPolicy::record_concurrent_mark_init_end(double
964 mark_init_elapsed_time_ms) {
965 _during_marking = true;
966 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
967 clear_during_initial_mark_pause();
968 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
969 }
971 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
972 _mark_remark_start_sec = os::elapsedTime();
973 _during_marking = false;
974 }
976 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
977 double end_time_sec = os::elapsedTime();
978 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
979 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
980 _cur_mark_stop_world_time_ms += elapsed_time_ms;
981 _prev_collection_pause_end_ms += elapsed_time_ms;
983 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
984 }
986 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
987 _mark_cleanup_start_sec = os::elapsedTime();
988 }
990 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
991 _last_young_gc = true;
992 _in_marking_window = false;
993 }
995 void G1CollectorPolicy::record_concurrent_pause() {
996 if (_stop_world_start > 0.0) {
997 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
998 _all_yield_times_ms->add(yield_ms);
999 }
1000 }
1002 void G1CollectorPolicy::record_concurrent_pause_end() {
1003 }
1005 template<class T>
1006 T sum_of(T* sum_arr, int start, int n, int N) {
1007 T sum = (T)0;
1008 for (int i = 0; i < n; i++) {
1009 int j = (start + i) % N;
1010 sum += sum_arr[j];
1011 }
1012 return sum;
1013 }
1015 void G1CollectorPolicy::print_par_stats(int level,
1016 const char* str,
1017 double* data) {
1018 double min = data[0], max = data[0];
1019 double total = 0.0;
1020 LineBuffer buf(level);
1021 buf.append("[%s (ms):", str);
1022 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1023 double val = data[i];
1024 if (val < min)
1025 min = val;
1026 if (val > max)
1027 max = val;
1028 total += val;
1029 buf.append(" %3.1lf", val);
1030 }
1031 buf.append_and_print_cr("");
1032 double avg = total / (double) no_of_gc_threads();
1033 buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
1034 avg, min, max, max - min);
1035 }
1037 void G1CollectorPolicy::print_par_sizes(int level,
1038 const char* str,
1039 double* data) {
1040 double min = data[0], max = data[0];
1041 double total = 0.0;
1042 LineBuffer buf(level);
1043 buf.append("[%s :", str);
1044 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1045 double val = data[i];
1046 if (val < min)
1047 min = val;
1048 if (val > max)
1049 max = val;
1050 total += val;
1051 buf.append(" %d", (int) val);
1052 }
1053 buf.append_and_print_cr("");
1054 double avg = total / (double) no_of_gc_threads();
1055 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1056 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1057 }
1059 void G1CollectorPolicy::print_stats(int level,
1060 const char* str,
1061 double value) {
1062 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1063 }
1065 void G1CollectorPolicy::print_stats(int level,
1066 const char* str,
1067 int value) {
1068 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1069 }
1071 double G1CollectorPolicy::avg_value(double* data) {
1072 if (G1CollectedHeap::use_parallel_gc_threads()) {
1073 double ret = 0.0;
1074 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1075 ret += data[i];
1076 }
1077 return ret / (double) no_of_gc_threads();
1078 } else {
1079 return data[0];
1080 }
1081 }
1083 double G1CollectorPolicy::max_value(double* data) {
1084 if (G1CollectedHeap::use_parallel_gc_threads()) {
1085 double ret = data[0];
1086 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1087 if (data[i] > ret) {
1088 ret = data[i];
1089 }
1090 }
1091 return ret;
1092 } else {
1093 return data[0];
1094 }
1095 }
1097 double G1CollectorPolicy::sum_of_values(double* data) {
1098 if (G1CollectedHeap::use_parallel_gc_threads()) {
1099 double sum = 0.0;
1100 for (uint i = 0; i < no_of_gc_threads(); i++) {
1101 sum += data[i];
1102 }
1103 return sum;
1104 } else {
1105 return data[0];
1106 }
1107 }
1109 double G1CollectorPolicy::max_sum(double* data1, double* data2) {
1110 double ret = data1[0] + data2[0];
1112 if (G1CollectedHeap::use_parallel_gc_threads()) {
1113 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1114 double data = data1[i] + data2[i];
1115 if (data > ret) {
1116 ret = data;
1117 }
1118 }
1119 }
1120 return ret;
1121 }
1123 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
1124 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
1125 return false;
1126 }
1128 size_t marking_initiating_used_threshold =
1129 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1130 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
1131 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
1133 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
1134 if (gcs_are_young()) {
1135 ergo_verbose5(ErgoConcCycles,
1136 "request concurrent cycle initiation",
1137 ergo_format_reason("occupancy higher than threshold")
1138 ergo_format_byte("occupancy")
1139 ergo_format_byte("allocation request")
1140 ergo_format_byte_perc("threshold")
1141 ergo_format_str("source"),
1142 cur_used_bytes,
1143 alloc_byte_size,
1144 marking_initiating_used_threshold,
1145 (double) InitiatingHeapOccupancyPercent,
1146 source);
1147 return true;
1148 } else {
1149 ergo_verbose5(ErgoConcCycles,
1150 "do not request concurrent cycle initiation",
1151 ergo_format_reason("still doing mixed collections")
1152 ergo_format_byte("occupancy")
1153 ergo_format_byte("allocation request")
1154 ergo_format_byte_perc("threshold")
1155 ergo_format_str("source"),
1156 cur_used_bytes,
1157 alloc_byte_size,
1158 marking_initiating_used_threshold,
1159 (double) InitiatingHeapOccupancyPercent,
1160 source);
1161 }
1162 }
1164 return false;
1165 }
1167 // Anything below that is considered to be zero
1168 #define MIN_TIMER_GRANULARITY 0.0000001
1170 void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
1171 double end_time_sec = os::elapsedTime();
1172 double elapsed_ms = _last_pause_time_ms;
1173 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1174 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1175 "otherwise, the subtraction below does not make sense");
1176 size_t rs_size =
1177 _cur_collection_pause_used_regions_at_start - cset_region_length();
1178 size_t cur_used_bytes = _g1->used();
1179 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1180 bool last_pause_included_initial_mark = false;
1181 bool update_stats = !_g1->evacuation_failed();
1182 set_no_of_gc_threads(no_of_gc_threads);
1184 #ifndef PRODUCT
1185 if (G1YoungSurvRateVerbose) {
1186 gclog_or_tty->print_cr("");
1187 _short_lived_surv_rate_group->print();
1188 // do that for any other surv rate groups too
1189 }
1190 #endif // PRODUCT
1192 last_pause_included_initial_mark = during_initial_mark_pause();
1193 if (last_pause_included_initial_mark) {
1194 record_concurrent_mark_init_end(0.0);
1195 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
1196 // Note: this might have already been set, if during the last
1197 // pause we decided to start a cycle but at the beginning of
1198 // this pause we decided to postpone it. That's OK.
1199 set_initiate_conc_mark_if_possible();
1200 }
1202 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1203 end_time_sec, false);
1205 // This assert is exempted when we're doing parallel collection pauses,
1206 // because the fragmentation caused by the parallel GC allocation buffers
1207 // can lead to more memory being used during collection than was used
1208 // before. Best leave this out until the fragmentation problem is fixed.
1209 // Pauses in which evacuation failed can also lead to negative
1210 // collections, since no space is reclaimed from a region containing an
1211 // object whose evacuation failed.
1212 // Further, we're now always doing parallel collection. But I'm still
1213 // leaving this here as a placeholder for a more precise assertion later.
1214 // (DLD, 10/05.)
1215 assert((true || parallel) // Always using GC LABs now.
1216 || _g1->evacuation_failed()
1217 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1218 "Negative collection");
1220 size_t freed_bytes =
1221 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1222 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1224 double survival_fraction =
1225 (double)surviving_bytes/
1226 (double)_collection_set_bytes_used_before;
1228 // These values are used to update the summary information that is
1229 // displayed when TraceGen0Time is enabled, and are output as part
1230 // of the PrintGCDetails output, in the non-parallel case.
1232 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1233 double satb_filtering_time = avg_value(_par_last_satb_filtering_times_ms);
1234 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1235 double update_rs_processed_buffers =
1236 sum_of_values(_par_last_update_rs_processed_buffers);
1237 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1238 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1239 double termination_time = avg_value(_par_last_termination_times_ms);
1241 double known_time = ext_root_scan_time +
1242 satb_filtering_time +
1243 update_rs_time +
1244 scan_rs_time +
1245 obj_copy_time;
1247 double other_time_ms = elapsed_ms;
1249 // Subtract the SATB drain time. It's initialized to zero at the
1250 // start of the pause and is updated during the pause if marking
1251 // is in progress.
1252 other_time_ms -= _cur_satb_drain_time_ms;
1254 // Subtract the root region scanning wait time. It's initialized to
1255 // zero at the start of the pause.
1256 other_time_ms -= _root_region_scan_wait_time_ms;
1258 if (parallel) {
1259 other_time_ms -= _cur_collection_par_time_ms;
1260 } else {
1261 other_time_ms -= known_time;
1262 }
1264 // Subtract the time taken to clean the card table from the
1265 // current value of "other time"
1266 other_time_ms -= _cur_clear_ct_time_ms;
1268 // Subtract the time spent completing marking in the collection
1269 // set. Note if marking is not in progress during the pause
1270 // the value of _mark_closure_time_ms will be zero.
1271 other_time_ms -= _mark_closure_time_ms;
1273 // TraceGen0Time and TraceGen1Time summary info updating.
1274 _all_pause_times_ms->add(elapsed_ms);
1276 if (update_stats) {
1277 _summary->record_total_time_ms(elapsed_ms);
1278 _summary->record_other_time_ms(other_time_ms);
1280 MainBodySummary* body_summary = _summary->main_body_summary();
1281 assert(body_summary != NULL, "should not be null!");
1283 // This will be non-zero iff marking is currently in progress (i.e.
1284 // _g1->mark_in_progress() == true) and the currrent pause was not
1285 // an initial mark pause. Since the body_summary items are NumberSeqs,
1286 // however, they have to be consistent and updated in lock-step with
1287 // each other. Therefore we unconditionally record the SATB drain
1288 // time - even if it's zero.
1289 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1290 body_summary->record_root_region_scan_wait_time_ms(
1291 _root_region_scan_wait_time_ms);
1293 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1294 body_summary->record_satb_filtering_time_ms(satb_filtering_time);
1295 body_summary->record_update_rs_time_ms(update_rs_time);
1296 body_summary->record_scan_rs_time_ms(scan_rs_time);
1297 body_summary->record_obj_copy_time_ms(obj_copy_time);
1299 if (parallel) {
1300 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1301 body_summary->record_termination_time_ms(termination_time);
1303 double parallel_known_time = known_time + termination_time;
1304 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1305 body_summary->record_parallel_other_time_ms(parallel_other_time);
1306 }
1308 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1309 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1311 // We exempt parallel collection from this check because Alloc Buffer
1312 // fragmentation can produce negative collections. Same with evac
1313 // failure.
1314 // Further, we're now always doing parallel collection. But I'm still
1315 // leaving this here as a placeholder for a more precise assertion later.
1316 // (DLD, 10/05.
1317 assert((true || parallel)
1318 || _g1->evacuation_failed()
1319 || surviving_bytes <= _collection_set_bytes_used_before,
1320 "Or else negative collection!");
1322 // this is where we update the allocation rate of the application
1323 double app_time_ms =
1324 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1325 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1326 // This usually happens due to the timer not having the required
1327 // granularity. Some Linuxes are the usual culprits.
1328 // We'll just set it to something (arbitrarily) small.
1329 app_time_ms = 1.0;
1330 }
1331 // We maintain the invariant that all objects allocated by mutator
1332 // threads will be allocated out of eden regions. So, we can use
1333 // the eden region number allocated since the previous GC to
1334 // calculate the application's allocate rate. The only exception
1335 // to that is humongous objects that are allocated separately. But
1336 // given that humongous object allocations do not really affect
1337 // either the pause's duration nor when the next pause will take
1338 // place we can safely ignore them here.
1339 size_t regions_allocated = eden_cset_region_length();
1340 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1341 _alloc_rate_ms_seq->add(alloc_rate_ms);
1343 double interval_ms =
1344 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1345 update_recent_gc_times(end_time_sec, elapsed_ms);
1346 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1347 if (recent_avg_pause_time_ratio() < 0.0 ||
1348 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1349 #ifndef PRODUCT
1350 // Dump info to allow post-facto debugging
1351 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1352 gclog_or_tty->print_cr("-------------------------------------------");
1353 gclog_or_tty->print_cr("Recent GC Times (ms):");
1354 _recent_gc_times_ms->dump();
1355 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1356 _recent_prev_end_times_for_all_gcs_sec->dump();
1357 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1358 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1359 // In debug mode, terminate the JVM if the user wants to debug at this point.
1360 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1361 #endif // !PRODUCT
1362 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1363 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1364 if (_recent_avg_pause_time_ratio < 0.0) {
1365 _recent_avg_pause_time_ratio = 0.0;
1366 } else {
1367 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1368 _recent_avg_pause_time_ratio = 1.0;
1369 }
1370 }
1371 }
1373 for (int i = 0; i < _aux_num; ++i) {
1374 if (_cur_aux_times_set[i]) {
1375 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1376 }
1377 }
1379 // PrintGCDetails output
1380 if (PrintGCDetails) {
1381 bool print_marking_info =
1382 _g1->mark_in_progress() && !last_pause_included_initial_mark;
1384 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1385 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1386 elapsed_ms / 1000.0);
1388 if (_root_region_scan_wait_time_ms > 0.0) {
1389 print_stats(1, "Root Region Scan Waiting", _root_region_scan_wait_time_ms);
1390 }
1391 if (parallel) {
1392 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1393 print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
1394 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1395 if (print_marking_info) {
1396 print_par_stats(2, "SATB Filtering", _par_last_satb_filtering_times_ms);
1397 }
1398 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1399 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1400 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1401 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1402 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1403 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1404 print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
1406 for (int i = 0; i < _parallel_gc_threads; i++) {
1407 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
1409 double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
1410 _par_last_satb_filtering_times_ms[i] +
1411 _par_last_update_rs_times_ms[i] +
1412 _par_last_scan_rs_times_ms[i] +
1413 _par_last_obj_copy_times_ms[i] +
1414 _par_last_termination_times_ms[i];
1416 _par_last_gc_worker_other_times_ms[i] = _cur_collection_par_time_ms - worker_known_time;
1417 }
1418 print_par_stats(2, "GC Worker", _par_last_gc_worker_times_ms);
1419 print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
1420 } else {
1421 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1422 if (print_marking_info) {
1423 print_stats(1, "SATB Filtering", satb_filtering_time);
1424 }
1425 print_stats(1, "Update RS", update_rs_time);
1426 print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
1427 print_stats(1, "Scan RS", scan_rs_time);
1428 print_stats(1, "Object Copying", obj_copy_time);
1429 }
1430 if (print_marking_info) {
1431 print_stats(1, "Complete CSet Marking", _mark_closure_time_ms);
1432 }
1433 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1434 #ifndef PRODUCT
1435 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1436 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1437 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1438 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1439 if (_num_cc_clears > 0) {
1440 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1441 }
1442 #endif
1443 print_stats(1, "Other", other_time_ms);
1444 print_stats(2, "Choose CSet",
1445 (_recorded_young_cset_choice_time_ms +
1446 _recorded_non_young_cset_choice_time_ms));
1447 print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
1448 print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
1449 print_stats(2, "Free CSet",
1450 (_recorded_young_free_cset_time_ms +
1451 _recorded_non_young_free_cset_time_ms));
1453 for (int i = 0; i < _aux_num; ++i) {
1454 if (_cur_aux_times_set[i]) {
1455 char buffer[96];
1456 sprintf(buffer, "Aux%d", i);
1457 print_stats(1, buffer, _cur_aux_times_ms[i]);
1458 }
1459 }
1460 }
1462 // Update the efficiency-since-mark vars.
1463 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1464 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1465 // This usually happens due to the timer not having the required
1466 // granularity. Some Linuxes are the usual culprits.
1467 // We'll just set it to something (arbitrarily) small.
1468 proc_ms = 1.0;
1469 }
1470 double cur_efficiency = (double) freed_bytes / proc_ms;
1472 bool new_in_marking_window = _in_marking_window;
1473 bool new_in_marking_window_im = false;
1474 if (during_initial_mark_pause()) {
1475 new_in_marking_window = true;
1476 new_in_marking_window_im = true;
1477 }
1479 if (_last_young_gc) {
1480 // This is supposed to to be the "last young GC" before we start
1481 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1483 if (!last_pause_included_initial_mark) {
1484 if (next_gc_should_be_mixed("start mixed GCs",
1485 "do not start mixed GCs")) {
1486 set_gcs_are_young(false);
1487 }
1488 } else {
1489 ergo_verbose0(ErgoMixedGCs,
1490 "do not start mixed GCs",
1491 ergo_format_reason("concurrent cycle is about to start"));
1492 }
1493 _last_young_gc = false;
1494 }
1496 if (!_last_gc_was_young) {
1497 // This is a mixed GC. Here we decide whether to continue doing
1498 // mixed GCs or not.
1500 if (!next_gc_should_be_mixed("continue mixed GCs",
1501 "do not continue mixed GCs")) {
1502 set_gcs_are_young(true);
1503 }
1504 }
1506 if (_last_gc_was_young && !_during_marking) {
1507 _young_gc_eff_seq->add(cur_efficiency);
1508 }
1510 _short_lived_surv_rate_group->start_adding_regions();
1511 // do that for any other surv rate groupsx
1513 if (update_stats) {
1514 double pause_time_ms = elapsed_ms;
1516 size_t diff = 0;
1517 if (_max_pending_cards >= _pending_cards)
1518 diff = _max_pending_cards - _pending_cards;
1519 _pending_card_diff_seq->add((double) diff);
1521 double cost_per_card_ms = 0.0;
1522 if (_pending_cards > 0) {
1523 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1524 _cost_per_card_ms_seq->add(cost_per_card_ms);
1525 }
1527 size_t cards_scanned = _g1->cards_scanned();
1529 double cost_per_entry_ms = 0.0;
1530 if (cards_scanned > 10) {
1531 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1532 if (_last_gc_was_young) {
1533 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1534 } else {
1535 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1536 }
1537 }
1539 if (_max_rs_lengths > 0) {
1540 double cards_per_entry_ratio =
1541 (double) cards_scanned / (double) _max_rs_lengths;
1542 if (_last_gc_was_young) {
1543 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1544 } else {
1545 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1546 }
1547 }
1549 // This is defensive. For a while _max_rs_lengths could get
1550 // smaller than _recorded_rs_lengths which was causing
1551 // rs_length_diff to get very large and mess up the RSet length
1552 // predictions. The reason was unsafe concurrent updates to the
1553 // _inc_cset_recorded_rs_lengths field which the code below guards
1554 // against (see CR 7118202). This bug has now been fixed (see CR
1555 // 7119027). However, I'm still worried that
1556 // _inc_cset_recorded_rs_lengths might still end up somewhat
1557 // inaccurate. The concurrent refinement thread calculates an
1558 // RSet's length concurrently with other CR threads updating it
1559 // which might cause it to calculate the length incorrectly (if,
1560 // say, it's in mid-coarsening). So I'll leave in the defensive
1561 // conditional below just in case.
1562 size_t rs_length_diff = 0;
1563 if (_max_rs_lengths > _recorded_rs_lengths) {
1564 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1565 }
1566 _rs_length_diff_seq->add((double) rs_length_diff);
1568 size_t copied_bytes = surviving_bytes;
1569 double cost_per_byte_ms = 0.0;
1570 if (copied_bytes > 0) {
1571 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1572 if (_in_marking_window) {
1573 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1574 } else {
1575 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1576 }
1577 }
1579 double all_other_time_ms = pause_time_ms -
1580 (update_rs_time + scan_rs_time + obj_copy_time +
1581 _mark_closure_time_ms + termination_time);
1583 double young_other_time_ms = 0.0;
1584 if (young_cset_region_length() > 0) {
1585 young_other_time_ms =
1586 _recorded_young_cset_choice_time_ms +
1587 _recorded_young_free_cset_time_ms;
1588 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1589 (double) young_cset_region_length());
1590 }
1591 double non_young_other_time_ms = 0.0;
1592 if (old_cset_region_length() > 0) {
1593 non_young_other_time_ms =
1594 _recorded_non_young_cset_choice_time_ms +
1595 _recorded_non_young_free_cset_time_ms;
1597 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1598 (double) old_cset_region_length());
1599 }
1601 double constant_other_time_ms = all_other_time_ms -
1602 (young_other_time_ms + non_young_other_time_ms);
1603 _constant_other_time_ms_seq->add(constant_other_time_ms);
1605 double survival_ratio = 0.0;
1606 if (_bytes_in_collection_set_before_gc > 0) {
1607 survival_ratio = (double) _bytes_copied_during_gc /
1608 (double) _bytes_in_collection_set_before_gc;
1609 }
1611 _pending_cards_seq->add((double) _pending_cards);
1612 _rs_lengths_seq->add((double) _max_rs_lengths);
1613 }
1615 _in_marking_window = new_in_marking_window;
1616 _in_marking_window_im = new_in_marking_window_im;
1617 _free_regions_at_end_of_collection = _g1->free_regions();
1618 update_young_list_target_length();
1620 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1621 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1622 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1624 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
1625 }
1627 #define EXT_SIZE_FORMAT "%d%s"
1628 #define EXT_SIZE_PARAMS(bytes) \
1629 byte_size_in_proper_unit((bytes)), \
1630 proper_unit_for_byte_size((bytes))
1632 void G1CollectorPolicy::print_heap_transition() {
1633 if (PrintGCDetails) {
1634 YoungList* young_list = _g1->young_list();
1635 size_t eden_bytes = young_list->eden_used_bytes();
1636 size_t survivor_bytes = young_list->survivor_used_bytes();
1637 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1638 size_t used = _g1->used();
1639 size_t capacity = _g1->capacity();
1640 size_t eden_capacity =
1641 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1643 gclog_or_tty->print_cr(
1644 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1645 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1646 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1647 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1648 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1649 EXT_SIZE_PARAMS(_prev_eden_capacity),
1650 EXT_SIZE_PARAMS(eden_bytes),
1651 EXT_SIZE_PARAMS(eden_capacity),
1652 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1653 EXT_SIZE_PARAMS(survivor_bytes),
1654 EXT_SIZE_PARAMS(used_before_gc),
1655 EXT_SIZE_PARAMS(_capacity_before_gc),
1656 EXT_SIZE_PARAMS(used),
1657 EXT_SIZE_PARAMS(capacity));
1659 _prev_eden_capacity = eden_capacity;
1660 } else if (PrintGC) {
1661 _g1->print_size_transition(gclog_or_tty,
1662 _cur_collection_pause_used_at_start_bytes,
1663 _g1->used(), _g1->capacity());
1664 }
1665 }
1667 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1668 double update_rs_processed_buffers,
1669 double goal_ms) {
1670 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1671 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1673 if (G1UseAdaptiveConcRefinement) {
1674 const int k_gy = 3, k_gr = 6;
1675 const double inc_k = 1.1, dec_k = 0.9;
1677 int g = cg1r->green_zone();
1678 if (update_rs_time > goal_ms) {
1679 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1680 } else {
1681 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1682 g = (int)MAX2(g * inc_k, g + 1.0);
1683 }
1684 }
1685 // Change the refinement threads params
1686 cg1r->set_green_zone(g);
1687 cg1r->set_yellow_zone(g * k_gy);
1688 cg1r->set_red_zone(g * k_gr);
1689 cg1r->reinitialize_threads();
1691 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1692 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1693 cg1r->yellow_zone());
1694 // Change the barrier params
1695 dcqs.set_process_completed_threshold(processing_threshold);
1696 dcqs.set_max_completed_queue(cg1r->red_zone());
1697 }
1699 int curr_queue_size = dcqs.completed_buffers_num();
1700 if (curr_queue_size >= cg1r->yellow_zone()) {
1701 dcqs.set_completed_queue_padding(curr_queue_size);
1702 } else {
1703 dcqs.set_completed_queue_padding(0);
1704 }
1705 dcqs.notify_if_necessary();
1706 }
1708 double
1709 G1CollectorPolicy::
1710 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1711 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1713 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1714 size_t young_num = g1h->young_list()->length();
1715 if (young_num == 0)
1716 return 0.0;
1718 young_num += adjustment;
1719 size_t pending_cards = predict_pending_cards();
1720 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1721 predict_rs_length_diff();
1722 size_t card_num;
1723 if (gcs_are_young()) {
1724 card_num = predict_young_card_num(rs_lengths);
1725 } else {
1726 card_num = predict_non_young_card_num(rs_lengths);
1727 }
1728 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1729 double accum_yg_surv_rate =
1730 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1732 size_t bytes_to_copy =
1733 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1735 return
1736 predict_rs_update_time_ms(pending_cards) +
1737 predict_rs_scan_time_ms(card_num) +
1738 predict_object_copy_time_ms(bytes_to_copy) +
1739 predict_young_other_time_ms(young_num) +
1740 predict_constant_other_time_ms();
1741 }
1743 double
1744 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1745 size_t rs_length = predict_rs_length_diff();
1746 size_t card_num;
1747 if (gcs_are_young()) {
1748 card_num = predict_young_card_num(rs_length);
1749 } else {
1750 card_num = predict_non_young_card_num(rs_length);
1751 }
1752 return predict_base_elapsed_time_ms(pending_cards, card_num);
1753 }
1755 double
1756 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1757 size_t scanned_cards) {
1758 return
1759 predict_rs_update_time_ms(pending_cards) +
1760 predict_rs_scan_time_ms(scanned_cards) +
1761 predict_constant_other_time_ms();
1762 }
1764 double
1765 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1766 bool young) {
1767 size_t rs_length = hr->rem_set()->occupied();
1768 size_t card_num;
1769 if (gcs_are_young()) {
1770 card_num = predict_young_card_num(rs_length);
1771 } else {
1772 card_num = predict_non_young_card_num(rs_length);
1773 }
1774 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1776 double region_elapsed_time_ms =
1777 predict_rs_scan_time_ms(card_num) +
1778 predict_object_copy_time_ms(bytes_to_copy);
1780 if (young)
1781 region_elapsed_time_ms += predict_young_other_time_ms(1);
1782 else
1783 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1785 return region_elapsed_time_ms;
1786 }
1788 size_t
1789 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1790 size_t bytes_to_copy;
1791 if (hr->is_marked())
1792 bytes_to_copy = hr->max_live_bytes();
1793 else {
1794 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1795 int age = hr->age_in_surv_rate_group();
1796 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1797 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1798 }
1799 return bytes_to_copy;
1800 }
1802 void
1803 G1CollectorPolicy::init_cset_region_lengths(size_t eden_cset_region_length,
1804 size_t survivor_cset_region_length) {
1805 _eden_cset_region_length = eden_cset_region_length;
1806 _survivor_cset_region_length = survivor_cset_region_length;
1807 _old_cset_region_length = 0;
1808 }
1810 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1811 _recorded_rs_lengths = rs_lengths;
1812 }
1814 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1815 double elapsed_ms) {
1816 _recent_gc_times_ms->add(elapsed_ms);
1817 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1818 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1819 }
1821 size_t G1CollectorPolicy::expansion_amount() {
1822 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1823 double threshold = _gc_overhead_perc;
1824 if (recent_gc_overhead > threshold) {
1825 // We will double the existing space, or take
1826 // G1ExpandByPercentOfAvailable % of the available expansion
1827 // space, whichever is smaller, bounded below by a minimum
1828 // expansion (unless that's all that's left.)
1829 const size_t min_expand_bytes = 1*M;
1830 size_t reserved_bytes = _g1->max_capacity();
1831 size_t committed_bytes = _g1->capacity();
1832 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1833 size_t expand_bytes;
1834 size_t expand_bytes_via_pct =
1835 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1836 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1837 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1838 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1840 ergo_verbose5(ErgoHeapSizing,
1841 "attempt heap expansion",
1842 ergo_format_reason("recent GC overhead higher than "
1843 "threshold after GC")
1844 ergo_format_perc("recent GC overhead")
1845 ergo_format_perc("threshold")
1846 ergo_format_byte("uncommitted")
1847 ergo_format_byte_perc("calculated expansion amount"),
1848 recent_gc_overhead, threshold,
1849 uncommitted_bytes,
1850 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1852 return expand_bytes;
1853 } else {
1854 return 0;
1855 }
1856 }
1858 class CountCSClosure: public HeapRegionClosure {
1859 G1CollectorPolicy* _g1_policy;
1860 public:
1861 CountCSClosure(G1CollectorPolicy* g1_policy) :
1862 _g1_policy(g1_policy) {}
1863 bool doHeapRegion(HeapRegion* r) {
1864 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
1865 return false;
1866 }
1867 };
1869 void G1CollectorPolicy::count_CS_bytes_used() {
1870 CountCSClosure cs_closure(this);
1871 _g1->collection_set_iterate(&cs_closure);
1872 }
1874 void G1CollectorPolicy::print_summary(int level,
1875 const char* str,
1876 NumberSeq* seq) const {
1877 double sum = seq->sum();
1878 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
1879 str, sum / 1000.0, seq->avg());
1880 }
1882 void G1CollectorPolicy::print_summary_sd(int level,
1883 const char* str,
1884 NumberSeq* seq) const {
1885 print_summary(level, str, seq);
1886 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
1887 seq->num(), seq->sd(), seq->maximum());
1888 }
1890 void G1CollectorPolicy::check_other_times(int level,
1891 NumberSeq* other_times_ms,
1892 NumberSeq* calc_other_times_ms) const {
1893 bool should_print = false;
1894 LineBuffer buf(level + 2);
1896 double max_sum = MAX2(fabs(other_times_ms->sum()),
1897 fabs(calc_other_times_ms->sum()));
1898 double min_sum = MIN2(fabs(other_times_ms->sum()),
1899 fabs(calc_other_times_ms->sum()));
1900 double sum_ratio = max_sum / min_sum;
1901 if (sum_ratio > 1.1) {
1902 should_print = true;
1903 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
1904 }
1906 double max_avg = MAX2(fabs(other_times_ms->avg()),
1907 fabs(calc_other_times_ms->avg()));
1908 double min_avg = MIN2(fabs(other_times_ms->avg()),
1909 fabs(calc_other_times_ms->avg()));
1910 double avg_ratio = max_avg / min_avg;
1911 if (avg_ratio > 1.1) {
1912 should_print = true;
1913 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
1914 }
1916 if (other_times_ms->sum() < -0.01) {
1917 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
1918 }
1920 if (other_times_ms->avg() < -0.01) {
1921 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
1922 }
1924 if (calc_other_times_ms->sum() < -0.01) {
1925 should_print = true;
1926 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
1927 }
1929 if (calc_other_times_ms->avg() < -0.01) {
1930 should_print = true;
1931 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
1932 }
1934 if (should_print)
1935 print_summary(level, "Other(Calc)", calc_other_times_ms);
1936 }
1938 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
1939 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1940 MainBodySummary* body_summary = summary->main_body_summary();
1941 if (summary->get_total_seq()->num() > 0) {
1942 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
1943 if (body_summary != NULL) {
1944 print_summary(1, "Root Region Scan Wait", body_summary->get_root_region_scan_wait_seq());
1945 if (parallel) {
1946 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
1947 print_summary(2, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1948 print_summary(2, "SATB Filtering", body_summary->get_satb_filtering_seq());
1949 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
1950 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
1951 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
1952 print_summary(2, "Termination", body_summary->get_termination_seq());
1953 print_summary(2, "Parallel Other", body_summary->get_parallel_other_seq());
1954 {
1955 NumberSeq* other_parts[] = {
1956 body_summary->get_ext_root_scan_seq(),
1957 body_summary->get_satb_filtering_seq(),
1958 body_summary->get_update_rs_seq(),
1959 body_summary->get_scan_rs_seq(),
1960 body_summary->get_obj_copy_seq(),
1961 body_summary->get_termination_seq()
1962 };
1963 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
1964 6, other_parts);
1965 check_other_times(2, body_summary->get_parallel_other_seq(),
1966 &calc_other_times_ms);
1967 }
1968 } else {
1969 print_summary(1, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1970 print_summary(1, "SATB Filtering", body_summary->get_satb_filtering_seq());
1971 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
1972 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
1973 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
1974 }
1975 }
1976 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
1977 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
1978 print_summary(1, "Other", summary->get_other_seq());
1979 {
1980 if (body_summary != NULL) {
1981 NumberSeq calc_other_times_ms;
1982 if (parallel) {
1983 // parallel
1984 NumberSeq* other_parts[] = {
1985 body_summary->get_satb_drain_seq(),
1986 body_summary->get_root_region_scan_wait_seq(),
1987 body_summary->get_parallel_seq(),
1988 body_summary->get_clear_ct_seq()
1989 };
1990 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
1991 4, other_parts);
1992 } else {
1993 // serial
1994 NumberSeq* other_parts[] = {
1995 body_summary->get_satb_drain_seq(),
1996 body_summary->get_root_region_scan_wait_seq(),
1997 body_summary->get_update_rs_seq(),
1998 body_summary->get_ext_root_scan_seq(),
1999 body_summary->get_satb_filtering_seq(),
2000 body_summary->get_scan_rs_seq(),
2001 body_summary->get_obj_copy_seq()
2002 };
2003 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2004 7, other_parts);
2005 }
2006 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2007 }
2008 }
2009 } else {
2010 LineBuffer(1).append_and_print_cr("none");
2011 }
2012 LineBuffer(0).append_and_print_cr("");
2013 }
2015 void G1CollectorPolicy::print_tracing_info() const {
2016 if (TraceGen0Time) {
2017 gclog_or_tty->print_cr("ALL PAUSES");
2018 print_summary_sd(0, "Total", _all_pause_times_ms);
2019 gclog_or_tty->print_cr("");
2020 gclog_or_tty->print_cr("");
2021 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2022 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2023 gclog_or_tty->print_cr("");
2025 gclog_or_tty->print_cr("EVACUATION PAUSES");
2026 print_summary(_summary);
2028 gclog_or_tty->print_cr("MISC");
2029 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2030 print_summary_sd(0, "Yields", _all_yield_times_ms);
2031 for (int i = 0; i < _aux_num; ++i) {
2032 if (_all_aux_times_ms[i].num() > 0) {
2033 char buffer[96];
2034 sprintf(buffer, "Aux%d", i);
2035 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2036 }
2037 }
2038 }
2039 if (TraceGen1Time) {
2040 if (_all_full_gc_times_ms->num() > 0) {
2041 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2042 _all_full_gc_times_ms->num(),
2043 _all_full_gc_times_ms->sum() / 1000.0);
2044 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2045 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2046 _all_full_gc_times_ms->sd(),
2047 _all_full_gc_times_ms->maximum());
2048 }
2049 }
2050 }
2052 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2053 #ifndef PRODUCT
2054 _short_lived_surv_rate_group->print_surv_rate_summary();
2055 // add this call for any other surv rate groups
2056 #endif // PRODUCT
2057 }
2059 #ifndef PRODUCT
2060 // for debugging, bit of a hack...
2061 static char*
2062 region_num_to_mbs(int length) {
2063 static char buffer[64];
2064 double bytes = (double) (length * HeapRegion::GrainBytes);
2065 double mbs = bytes / (double) (1024 * 1024);
2066 sprintf(buffer, "%7.2lfMB", mbs);
2067 return buffer;
2068 }
2069 #endif // PRODUCT
2071 size_t G1CollectorPolicy::max_regions(int purpose) {
2072 switch (purpose) {
2073 case GCAllocForSurvived:
2074 return _max_survivor_regions;
2075 case GCAllocForTenured:
2076 return REGIONS_UNLIMITED;
2077 default:
2078 ShouldNotReachHere();
2079 return REGIONS_UNLIMITED;
2080 };
2081 }
2083 void G1CollectorPolicy::update_max_gc_locker_expansion() {
2084 size_t expansion_region_num = 0;
2085 if (GCLockerEdenExpansionPercent > 0) {
2086 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2087 double expansion_region_num_d = perc * (double) _young_list_target_length;
2088 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2089 // less than 1.0) we'll get 1.
2090 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2091 } else {
2092 assert(expansion_region_num == 0, "sanity");
2093 }
2094 _young_list_max_length = _young_list_target_length + expansion_region_num;
2095 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2096 }
2098 // Calculates survivor space parameters.
2099 void G1CollectorPolicy::update_survivors_policy() {
2100 double max_survivor_regions_d =
2101 (double) _young_list_target_length / (double) SurvivorRatio;
2102 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
2103 // smaller than 1.0) we'll get 1.
2104 _max_survivor_regions = (size_t) ceil(max_survivor_regions_d);
2106 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2107 HeapRegion::GrainWords * _max_survivor_regions);
2108 }
2110 #ifndef PRODUCT
2111 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2112 CollectionSetChooser* _chooser;
2113 public:
2114 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2115 _chooser(chooser) {}
2117 bool doHeapRegion(HeapRegion* r) {
2118 if (!r->continuesHumongous()) {
2119 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2120 }
2121 return false;
2122 }
2123 };
2125 bool G1CollectorPolicy::assertMarkedBytesDataOK() {
2126 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2127 _g1->heap_region_iterate(&cl);
2128 return true;
2129 }
2130 #endif
2132 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
2133 GCCause::Cause gc_cause) {
2134 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2135 if (!during_cycle) {
2136 ergo_verbose1(ErgoConcCycles,
2137 "request concurrent cycle initiation",
2138 ergo_format_reason("requested by GC cause")
2139 ergo_format_str("GC cause"),
2140 GCCause::to_string(gc_cause));
2141 set_initiate_conc_mark_if_possible();
2142 return true;
2143 } else {
2144 ergo_verbose1(ErgoConcCycles,
2145 "do not request concurrent cycle initiation",
2146 ergo_format_reason("concurrent cycle already in progress")
2147 ergo_format_str("GC cause"),
2148 GCCause::to_string(gc_cause));
2149 return false;
2150 }
2151 }
2153 void
2154 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2155 // We are about to decide on whether this pause will be an
2156 // initial-mark pause.
2158 // First, during_initial_mark_pause() should not be already set. We
2159 // will set it here if we have to. However, it should be cleared by
2160 // the end of the pause (it's only set for the duration of an
2161 // initial-mark pause).
2162 assert(!during_initial_mark_pause(), "pre-condition");
2164 if (initiate_conc_mark_if_possible()) {
2165 // We had noticed on a previous pause that the heap occupancy has
2166 // gone over the initiating threshold and we should start a
2167 // concurrent marking cycle. So we might initiate one.
2169 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2170 if (!during_cycle) {
2171 // The concurrent marking thread is not "during a cycle", i.e.,
2172 // it has completed the last one. So we can go ahead and
2173 // initiate a new cycle.
2175 set_during_initial_mark_pause();
2176 // We do not allow mixed GCs during marking.
2177 if (!gcs_are_young()) {
2178 set_gcs_are_young(true);
2179 ergo_verbose0(ErgoMixedGCs,
2180 "end mixed GCs",
2181 ergo_format_reason("concurrent cycle is about to start"));
2182 }
2184 // And we can now clear initiate_conc_mark_if_possible() as
2185 // we've already acted on it.
2186 clear_initiate_conc_mark_if_possible();
2188 ergo_verbose0(ErgoConcCycles,
2189 "initiate concurrent cycle",
2190 ergo_format_reason("concurrent cycle initiation requested"));
2191 } else {
2192 // The concurrent marking thread is still finishing up the
2193 // previous cycle. If we start one right now the two cycles
2194 // overlap. In particular, the concurrent marking thread might
2195 // be in the process of clearing the next marking bitmap (which
2196 // we will use for the next cycle if we start one). Starting a
2197 // cycle now will be bad given that parts of the marking
2198 // information might get cleared by the marking thread. And we
2199 // cannot wait for the marking thread to finish the cycle as it
2200 // periodically yields while clearing the next marking bitmap
2201 // and, if it's in a yield point, it's waiting for us to
2202 // finish. So, at this point we will not start a cycle and we'll
2203 // let the concurrent marking thread complete the last one.
2204 ergo_verbose0(ErgoConcCycles,
2205 "do not initiate concurrent cycle",
2206 ergo_format_reason("concurrent cycle already in progress"));
2207 }
2208 }
2209 }
2211 class KnownGarbageClosure: public HeapRegionClosure {
2212 G1CollectedHeap* _g1h;
2213 CollectionSetChooser* _hrSorted;
2215 public:
2216 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2217 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
2219 bool doHeapRegion(HeapRegion* r) {
2220 // We only include humongous regions in collection
2221 // sets when concurrent mark shows that their contained object is
2222 // unreachable.
2224 // Do we have any marking information for this region?
2225 if (r->is_marked()) {
2226 // We will skip any region that's currently used as an old GC
2227 // alloc region (we should not consider those for collection
2228 // before we fill them up).
2229 if (_hrSorted->shouldAdd(r) && !_g1h->is_old_gc_alloc_region(r)) {
2230 _hrSorted->addMarkedHeapRegion(r);
2231 }
2232 }
2233 return false;
2234 }
2235 };
2237 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2238 G1CollectedHeap* _g1h;
2239 CollectionSetChooser* _hrSorted;
2240 jint _marked_regions_added;
2241 size_t _reclaimable_bytes_added;
2242 jint _chunk_size;
2243 jint _cur_chunk_idx;
2244 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2245 int _worker;
2246 int _invokes;
2248 void get_new_chunk() {
2249 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2250 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2251 }
2252 void add_region(HeapRegion* r) {
2253 if (_cur_chunk_idx == _cur_chunk_end) {
2254 get_new_chunk();
2255 }
2256 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2257 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2258 _marked_regions_added++;
2259 _reclaimable_bytes_added += r->reclaimable_bytes();
2260 _cur_chunk_idx++;
2261 }
2263 public:
2264 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2265 jint chunk_size,
2266 int worker) :
2267 _g1h(G1CollectedHeap::heap()),
2268 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2269 _marked_regions_added(0), _reclaimable_bytes_added(0),
2270 _cur_chunk_idx(0), _cur_chunk_end(0), _invokes(0) { }
2272 bool doHeapRegion(HeapRegion* r) {
2273 // We only include humongous regions in collection
2274 // sets when concurrent mark shows that their contained object is
2275 // unreachable.
2276 _invokes++;
2278 // Do we have any marking information for this region?
2279 if (r->is_marked()) {
2280 // We will skip any region that's currently used as an old GC
2281 // alloc region (we should not consider those for collection
2282 // before we fill them up).
2283 if (_hrSorted->shouldAdd(r) && !_g1h->is_old_gc_alloc_region(r)) {
2284 add_region(r);
2285 }
2286 }
2287 return false;
2288 }
2289 jint marked_regions_added() { return _marked_regions_added; }
2290 size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
2291 int invokes() { return _invokes; }
2292 };
2294 class ParKnownGarbageTask: public AbstractGangTask {
2295 CollectionSetChooser* _hrSorted;
2296 jint _chunk_size;
2297 G1CollectedHeap* _g1;
2298 public:
2299 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2300 AbstractGangTask("ParKnownGarbageTask"),
2301 _hrSorted(hrSorted), _chunk_size(chunk_size),
2302 _g1(G1CollectedHeap::heap()) { }
2304 void work(uint worker_id) {
2305 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted,
2306 _chunk_size,
2307 worker_id);
2308 // Back to zero for the claim value.
2309 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
2310 _g1->workers()->active_workers(),
2311 HeapRegion::InitialClaimValue);
2312 jint regions_added = parKnownGarbageCl.marked_regions_added();
2313 size_t reclaimable_bytes_added =
2314 parKnownGarbageCl.reclaimable_bytes_added();
2315 _hrSorted->updateTotals(regions_added, reclaimable_bytes_added);
2316 if (G1PrintParCleanupStats) {
2317 gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
2318 worker_id, parKnownGarbageCl.invokes(), regions_added);
2319 }
2320 }
2321 };
2323 void
2324 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
2325 double start_sec;
2326 if (G1PrintParCleanupStats) {
2327 start_sec = os::elapsedTime();
2328 }
2330 _collectionSetChooser->clearMarkedHeapRegions();
2331 double clear_marked_end_sec;
2332 if (G1PrintParCleanupStats) {
2333 clear_marked_end_sec = os::elapsedTime();
2334 gclog_or_tty->print_cr(" clear marked regions: %8.3f ms.",
2335 (clear_marked_end_sec - start_sec) * 1000.0);
2336 }
2338 if (G1CollectedHeap::use_parallel_gc_threads()) {
2339 const size_t OverpartitionFactor = 4;
2340 size_t WorkUnit;
2341 // The use of MinChunkSize = 8 in the original code
2342 // causes some assertion failures when the total number of
2343 // region is less than 8. The code here tries to fix that.
2344 // Should the original code also be fixed?
2345 if (no_of_gc_threads > 0) {
2346 const size_t MinWorkUnit =
2347 MAX2(_g1->n_regions() / no_of_gc_threads, (size_t) 1U);
2348 WorkUnit =
2349 MAX2(_g1->n_regions() / (no_of_gc_threads * OverpartitionFactor),
2350 MinWorkUnit);
2351 } else {
2352 assert(no_of_gc_threads > 0,
2353 "The active gc workers should be greater than 0");
2354 // In a product build do something reasonable to avoid a crash.
2355 const size_t MinWorkUnit =
2356 MAX2(_g1->n_regions() / ParallelGCThreads, (size_t) 1U);
2357 WorkUnit =
2358 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2359 MinWorkUnit);
2360 }
2361 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2362 WorkUnit);
2363 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2364 (int) WorkUnit);
2365 _g1->workers()->run_task(&parKnownGarbageTask);
2367 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2368 "sanity check");
2369 } else {
2370 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2371 _g1->heap_region_iterate(&knownGarbagecl);
2372 }
2373 double known_garbage_end_sec;
2374 if (G1PrintParCleanupStats) {
2375 known_garbage_end_sec = os::elapsedTime();
2376 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2377 (known_garbage_end_sec - clear_marked_end_sec) * 1000.0);
2378 }
2380 _collectionSetChooser->sortMarkedHeapRegions();
2381 double end_sec = os::elapsedTime();
2382 if (G1PrintParCleanupStats) {
2383 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2384 (end_sec - known_garbage_end_sec) * 1000.0);
2385 }
2387 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
2388 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
2389 _cur_mark_stop_world_time_ms += elapsed_time_ms;
2390 _prev_collection_pause_end_ms += elapsed_time_ms;
2391 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
2392 }
2394 // Add the heap region at the head of the non-incremental collection set
2395 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
2396 assert(_inc_cset_build_state == Active, "Precondition");
2397 assert(!hr->is_young(), "non-incremental add of young region");
2399 assert(!hr->in_collection_set(), "should not already be in the CSet");
2400 hr->set_in_collection_set(true);
2401 hr->set_next_in_collection_set(_collection_set);
2402 _collection_set = hr;
2403 _collection_set_bytes_used_before += hr->used();
2404 _g1->register_region_with_in_cset_fast_test(hr);
2405 size_t rs_length = hr->rem_set()->occupied();
2406 _recorded_rs_lengths += rs_length;
2407 _old_cset_region_length += 1;
2408 }
2410 // Initialize the per-collection-set information
2411 void G1CollectorPolicy::start_incremental_cset_building() {
2412 assert(_inc_cset_build_state == Inactive, "Precondition");
2414 _inc_cset_head = NULL;
2415 _inc_cset_tail = NULL;
2416 _inc_cset_bytes_used_before = 0;
2418 _inc_cset_max_finger = 0;
2419 _inc_cset_recorded_rs_lengths = 0;
2420 _inc_cset_recorded_rs_lengths_diffs = 0;
2421 _inc_cset_predicted_elapsed_time_ms = 0.0;
2422 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2423 _inc_cset_build_state = Active;
2424 }
2426 void G1CollectorPolicy::finalize_incremental_cset_building() {
2427 assert(_inc_cset_build_state == Active, "Precondition");
2428 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2430 // The two "main" fields, _inc_cset_recorded_rs_lengths and
2431 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
2432 // that adds a new region to the CSet. Further updates by the
2433 // concurrent refinement thread that samples the young RSet lengths
2434 // are accumulated in the *_diffs fields. Here we add the diffs to
2435 // the "main" fields.
2437 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
2438 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
2439 } else {
2440 // This is defensive. The diff should in theory be always positive
2441 // as RSets can only grow between GCs. However, given that we
2442 // sample their size concurrently with other threads updating them
2443 // it's possible that we might get the wrong size back, which
2444 // could make the calculations somewhat inaccurate.
2445 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
2446 if (_inc_cset_recorded_rs_lengths >= diffs) {
2447 _inc_cset_recorded_rs_lengths -= diffs;
2448 } else {
2449 _inc_cset_recorded_rs_lengths = 0;
2450 }
2451 }
2452 _inc_cset_predicted_elapsed_time_ms +=
2453 _inc_cset_predicted_elapsed_time_ms_diffs;
2455 _inc_cset_recorded_rs_lengths_diffs = 0;
2456 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2457 }
2459 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2460 // This routine is used when:
2461 // * adding survivor regions to the incremental cset at the end of an
2462 // evacuation pause,
2463 // * adding the current allocation region to the incremental cset
2464 // when it is retired, and
2465 // * updating existing policy information for a region in the
2466 // incremental cset via young list RSet sampling.
2467 // Therefore this routine may be called at a safepoint by the
2468 // VM thread, or in-between safepoints by mutator threads (when
2469 // retiring the current allocation region) or a concurrent
2470 // refine thread (RSet sampling).
2472 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2473 size_t used_bytes = hr->used();
2474 _inc_cset_recorded_rs_lengths += rs_length;
2475 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2476 _inc_cset_bytes_used_before += used_bytes;
2478 // Cache the values we have added to the aggregated informtion
2479 // in the heap region in case we have to remove this region from
2480 // the incremental collection set, or it is updated by the
2481 // rset sampling code
2482 hr->set_recorded_rs_length(rs_length);
2483 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2484 }
2486 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
2487 size_t new_rs_length) {
2488 // Update the CSet information that is dependent on the new RS length
2489 assert(hr->is_young(), "Precondition");
2490 assert(!SafepointSynchronize::is_at_safepoint(),
2491 "should not be at a safepoint");
2493 // We could have updated _inc_cset_recorded_rs_lengths and
2494 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
2495 // that atomically, as this code is executed by a concurrent
2496 // refinement thread, potentially concurrently with a mutator thread
2497 // allocating a new region and also updating the same fields. To
2498 // avoid the atomic operations we accumulate these updates on two
2499 // separate fields (*_diffs) and we'll just add them to the "main"
2500 // fields at the start of a GC.
2502 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
2503 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
2504 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
2506 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2507 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2508 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
2509 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
2511 hr->set_recorded_rs_length(new_rs_length);
2512 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
2513 }
2515 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2516 assert(hr->is_young(), "invariant");
2517 assert(hr->young_index_in_cset() > -1, "should have already been set");
2518 assert(_inc_cset_build_state == Active, "Precondition");
2520 // We need to clear and set the cached recorded/cached collection set
2521 // information in the heap region here (before the region gets added
2522 // to the collection set). An individual heap region's cached values
2523 // are calculated, aggregated with the policy collection set info,
2524 // and cached in the heap region here (initially) and (subsequently)
2525 // by the Young List sampling code.
2527 size_t rs_length = hr->rem_set()->occupied();
2528 add_to_incremental_cset_info(hr, rs_length);
2530 HeapWord* hr_end = hr->end();
2531 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2533 assert(!hr->in_collection_set(), "invariant");
2534 hr->set_in_collection_set(true);
2535 assert( hr->next_in_collection_set() == NULL, "invariant");
2537 _g1->register_region_with_in_cset_fast_test(hr);
2538 }
2540 // Add the region at the RHS of the incremental cset
2541 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2542 // We should only ever be appending survivors at the end of a pause
2543 assert( hr->is_survivor(), "Logic");
2545 // Do the 'common' stuff
2546 add_region_to_incremental_cset_common(hr);
2548 // Now add the region at the right hand side
2549 if (_inc_cset_tail == NULL) {
2550 assert(_inc_cset_head == NULL, "invariant");
2551 _inc_cset_head = hr;
2552 } else {
2553 _inc_cset_tail->set_next_in_collection_set(hr);
2554 }
2555 _inc_cset_tail = hr;
2556 }
2558 // Add the region to the LHS of the incremental cset
2559 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2560 // Survivors should be added to the RHS at the end of a pause
2561 assert(!hr->is_survivor(), "Logic");
2563 // Do the 'common' stuff
2564 add_region_to_incremental_cset_common(hr);
2566 // Add the region at the left hand side
2567 hr->set_next_in_collection_set(_inc_cset_head);
2568 if (_inc_cset_head == NULL) {
2569 assert(_inc_cset_tail == NULL, "Invariant");
2570 _inc_cset_tail = hr;
2571 }
2572 _inc_cset_head = hr;
2573 }
2575 #ifndef PRODUCT
2576 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2577 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2579 st->print_cr("\nCollection_set:");
2580 HeapRegion* csr = list_head;
2581 while (csr != NULL) {
2582 HeapRegion* next = csr->next_in_collection_set();
2583 assert(csr->in_collection_set(), "bad CS");
2584 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2585 "age: %4d, y: %d, surv: %d",
2586 csr->bottom(), csr->end(),
2587 csr->top(),
2588 csr->prev_top_at_mark_start(),
2589 csr->next_top_at_mark_start(),
2590 csr->top_at_conc_mark_count(),
2591 csr->age_in_surv_rate_group_cond(),
2592 csr->is_young(),
2593 csr->is_survivor());
2594 csr = next;
2595 }
2596 }
2597 #endif // !PRODUCT
2599 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2600 const char* false_action_str) {
2601 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2602 if (cset_chooser->isEmpty()) {
2603 ergo_verbose0(ErgoMixedGCs,
2604 false_action_str,
2605 ergo_format_reason("candidate old regions not available"));
2606 return false;
2607 }
2608 size_t reclaimable_bytes = cset_chooser->remainingReclaimableBytes();
2609 size_t capacity_bytes = _g1->capacity();
2610 double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2611 double threshold = (double) G1OldReclaimableThresholdPercent;
2612 if (perc < threshold) {
2613 ergo_verbose4(ErgoMixedGCs,
2614 false_action_str,
2615 ergo_format_reason("reclaimable percentage lower than threshold")
2616 ergo_format_region("candidate old regions")
2617 ergo_format_byte_perc("reclaimable")
2618 ergo_format_perc("threshold"),
2619 cset_chooser->remainingRegions(),
2620 reclaimable_bytes, perc, threshold);
2621 return false;
2622 }
2624 ergo_verbose4(ErgoMixedGCs,
2625 true_action_str,
2626 ergo_format_reason("candidate old regions available")
2627 ergo_format_region("candidate old regions")
2628 ergo_format_byte_perc("reclaimable")
2629 ergo_format_perc("threshold"),
2630 cset_chooser->remainingRegions(),
2631 reclaimable_bytes, perc, threshold);
2632 return true;
2633 }
2635 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
2636 // Set this here - in case we're not doing young collections.
2637 double non_young_start_time_sec = os::elapsedTime();
2639 YoungList* young_list = _g1->young_list();
2640 finalize_incremental_cset_building();
2642 guarantee(target_pause_time_ms > 0.0,
2643 err_msg("target_pause_time_ms = %1.6lf should be positive",
2644 target_pause_time_ms));
2645 guarantee(_collection_set == NULL, "Precondition");
2647 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2648 double predicted_pause_time_ms = base_time_ms;
2649 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2651 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2652 "start choosing CSet",
2653 ergo_format_ms("predicted base time")
2654 ergo_format_ms("remaining time")
2655 ergo_format_ms("target pause time"),
2656 base_time_ms, time_remaining_ms, target_pause_time_ms);
2658 HeapRegion* hr;
2659 double young_start_time_sec = os::elapsedTime();
2661 _collection_set_bytes_used_before = 0;
2662 _last_gc_was_young = gcs_are_young() ? true : false;
2664 if (_last_gc_was_young) {
2665 ++_young_pause_num;
2666 } else {
2667 ++_mixed_pause_num;
2668 }
2670 // The young list is laid with the survivor regions from the previous
2671 // pause are appended to the RHS of the young list, i.e.
2672 // [Newly Young Regions ++ Survivors from last pause].
2674 size_t survivor_region_length = young_list->survivor_length();
2675 size_t eden_region_length = young_list->length() - survivor_region_length;
2676 init_cset_region_lengths(eden_region_length, survivor_region_length);
2677 hr = young_list->first_survivor_region();
2678 while (hr != NULL) {
2679 assert(hr->is_survivor(), "badly formed young list");
2680 hr->set_young();
2681 hr = hr->get_next_young_region();
2682 }
2684 // Clear the fields that point to the survivor list - they are all young now.
2685 young_list->clear_survivors();
2687 _collection_set = _inc_cset_head;
2688 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2689 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2690 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2692 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2693 "add young regions to CSet",
2694 ergo_format_region("eden")
2695 ergo_format_region("survivors")
2696 ergo_format_ms("predicted young region time"),
2697 eden_region_length, survivor_region_length,
2698 _inc_cset_predicted_elapsed_time_ms);
2700 // The number of recorded young regions is the incremental
2701 // collection set's current size
2702 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2704 double young_end_time_sec = os::elapsedTime();
2705 _recorded_young_cset_choice_time_ms =
2706 (young_end_time_sec - young_start_time_sec) * 1000.0;
2708 // We are doing young collections so reset this.
2709 non_young_start_time_sec = young_end_time_sec;
2711 if (!gcs_are_young()) {
2712 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2713 assert(cset_chooser->verify(), "CSet Chooser verification - pre");
2714 const size_t min_old_cset_length = cset_chooser->calcMinOldCSetLength();
2715 const size_t max_old_cset_length = cset_chooser->calcMaxOldCSetLength();
2717 size_t expensive_region_num = 0;
2718 bool check_time_remaining = adaptive_young_list_length();
2719 HeapRegion* hr = cset_chooser->peek();
2720 while (hr != NULL) {
2721 if (old_cset_region_length() >= max_old_cset_length) {
2722 // Added maximum number of old regions to the CSet.
2723 ergo_verbose2(ErgoCSetConstruction,
2724 "finish adding old regions to CSet",
2725 ergo_format_reason("old CSet region num reached max")
2726 ergo_format_region("old")
2727 ergo_format_region("max"),
2728 old_cset_region_length(), max_old_cset_length);
2729 break;
2730 }
2732 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2733 if (check_time_remaining) {
2734 if (predicted_time_ms > time_remaining_ms) {
2735 // Too expensive for the current CSet.
2737 if (old_cset_region_length() >= min_old_cset_length) {
2738 // We have added the minimum number of old regions to the CSet,
2739 // we are done with this CSet.
2740 ergo_verbose4(ErgoCSetConstruction,
2741 "finish adding old regions to CSet",
2742 ergo_format_reason("predicted time is too high")
2743 ergo_format_ms("predicted time")
2744 ergo_format_ms("remaining time")
2745 ergo_format_region("old")
2746 ergo_format_region("min"),
2747 predicted_time_ms, time_remaining_ms,
2748 old_cset_region_length(), min_old_cset_length);
2749 break;
2750 }
2752 // We'll add it anyway given that we haven't reached the
2753 // minimum number of old regions.
2754 expensive_region_num += 1;
2755 }
2756 } else {
2757 if (old_cset_region_length() >= min_old_cset_length) {
2758 // In the non-auto-tuning case, we'll finish adding regions
2759 // to the CSet if we reach the minimum.
2760 ergo_verbose2(ErgoCSetConstruction,
2761 "finish adding old regions to CSet",
2762 ergo_format_reason("old CSet region num reached min")
2763 ergo_format_region("old")
2764 ergo_format_region("min"),
2765 old_cset_region_length(), min_old_cset_length);
2766 break;
2767 }
2768 }
2770 // We will add this region to the CSet.
2771 time_remaining_ms -= predicted_time_ms;
2772 predicted_pause_time_ms += predicted_time_ms;
2773 cset_chooser->remove_and_move_to_next(hr);
2774 _g1->old_set_remove(hr);
2775 add_old_region_to_cset(hr);
2777 hr = cset_chooser->peek();
2778 }
2779 if (hr == NULL) {
2780 ergo_verbose0(ErgoCSetConstruction,
2781 "finish adding old regions to CSet",
2782 ergo_format_reason("candidate old regions not available"));
2783 }
2785 if (expensive_region_num > 0) {
2786 // We print the information once here at the end, predicated on
2787 // whether we added any apparently expensive regions or not, to
2788 // avoid generating output per region.
2789 ergo_verbose4(ErgoCSetConstruction,
2790 "added expensive regions to CSet",
2791 ergo_format_reason("old CSet region num not reached min")
2792 ergo_format_region("old")
2793 ergo_format_region("expensive")
2794 ergo_format_region("min")
2795 ergo_format_ms("remaining time"),
2796 old_cset_region_length(),
2797 expensive_region_num,
2798 min_old_cset_length,
2799 time_remaining_ms);
2800 }
2802 assert(cset_chooser->verify(), "CSet Chooser verification - post");
2803 }
2805 stop_incremental_cset_building();
2807 count_CS_bytes_used();
2809 ergo_verbose5(ErgoCSetConstruction,
2810 "finish choosing CSet",
2811 ergo_format_region("eden")
2812 ergo_format_region("survivors")
2813 ergo_format_region("old")
2814 ergo_format_ms("predicted pause time")
2815 ergo_format_ms("target pause time"),
2816 eden_region_length, survivor_region_length,
2817 old_cset_region_length(),
2818 predicted_pause_time_ms, target_pause_time_ms);
2820 double non_young_end_time_sec = os::elapsedTime();
2821 _recorded_non_young_cset_choice_time_ms =
2822 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2823 }