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 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/g1Log.hpp"
33 #include "gc_implementation/g1/heapRegionRemSet.hpp"
34 #include "gc_implementation/shared/gcPolicyCounters.hpp"
35 #include "runtime/arguments.hpp"
36 #include "runtime/java.hpp"
37 #include "runtime/mutexLocker.hpp"
38 #include "utilities/debug.hpp"
39
40 // Different defaults for different number of GC threads
41 // They were chosen by running GCOld and SPECjbb on debris with different
42 // numbers of GC threads and choosing them based on the results
43
44 // all the same
45 static double rs_length_diff_defaults[] = {
46 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
47 };
48
49 static double cost_per_card_ms_defaults[] = {
50 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
51 };
52
53 // all the same
54 static double young_cards_per_entry_ratio_defaults[] = {
55 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
56 };
57
58 static double cost_per_entry_ms_defaults[] = {
59 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
60 };
61
62 static double cost_per_byte_ms_defaults[] = {
63 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
64 };
65
66 // these should be pretty consistent
67 static double constant_other_time_ms_defaults[] = {
68 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
69 };
70
71
72 static double young_other_cost_per_region_ms_defaults[] = {
73 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
74 };
75
76 static double non_young_other_cost_per_region_ms_defaults[] = {
77 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
78 };
79
80 // Help class for avoiding interleaved logging
81 class LineBuffer: public StackObj {
82
83 private:
84 static const int BUFFER_LEN = 1024;
85 static const int INDENT_CHARS = 3;
86 char _buffer[BUFFER_LEN];
87 int _indent_level;
88 int _cur;
89
90 void vappend(const char* format, va_list ap) {
91 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
92 if (res != -1) {
93 _cur += res;
94 } else {
95 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
96 _buffer[BUFFER_LEN -1] = 0;
97 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
98 }
99 }
100
101 public:
102 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
103 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
104 _buffer[_cur] = ' ';
105 }
106 }
107
108 #ifndef PRODUCT
109 ~LineBuffer() {
110 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
111 }
112 #endif
113
114 void append(const char* format, ...) {
115 va_list ap;
116 va_start(ap, format);
117 vappend(format, ap);
118 va_end(ap);
119 }
120
121 void append_and_print_cr(const char* format, ...) {
122 va_list ap;
123 va_start(ap, format);
124 vappend(format, ap);
125 va_end(ap);
126 gclog_or_tty->print_cr("%s", _buffer);
127 _cur = _indent_level * INDENT_CHARS;
128 }
129 };
130
131 G1CollectorPolicy::G1CollectorPolicy() :
132 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
133 ? ParallelGCThreads : 1),
134
135 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
136 _all_pause_times_ms(new NumberSeq()),
137 _stop_world_start(0.0),
138 _all_stop_world_times_ms(new NumberSeq()),
139 _all_yield_times_ms(new NumberSeq()),
140
141 _summary(new Summary()),
142
143 _cur_clear_ct_time_ms(0.0),
144 _root_region_scan_wait_time_ms(0.0),
145
146 _cur_ref_proc_time_ms(0.0),
147 _cur_ref_enq_time_ms(0.0),
148
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
156
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]),
162
163 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
164 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
165
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)),
181
182 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
183 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
184
185 _pause_time_target_ms((double) MaxGCPauseMillis),
186
187 _gcs_are_young(true),
188 _young_pause_num(0),
189 _mixed_pause_num(0),
190
191 _during_marking(false),
192 _in_marking_window(false),
193 _in_marking_window_im(false),
194
195 _recent_prev_end_times_for_all_gcs_sec(
196 new TruncatedSeq(NumPrevPausesForHeuristics)),
197
198 _recent_avg_pause_time_ratio(0.0),
199
200 _all_full_gc_times_ms(new NumberSeq()),
201
202 _initiate_conc_mark_if_possible(false),
203 _during_initial_mark_pause(false),
204 _last_young_gc(false),
205 _last_gc_was_young(false),
206
207 _eden_bytes_before_gc(0),
208 _survivor_bytes_before_gc(0),
209 _capacity_before_gc(0),
210
211 _eden_cset_region_length(0),
212 _survivor_cset_region_length(0),
213 _old_cset_region_length(0),
214
215 _collection_set(NULL),
216 _collection_set_bytes_used_before(0),
217
218 // Incremental CSet attributes
219 _inc_cset_build_state(Inactive),
220 _inc_cset_head(NULL),
221 _inc_cset_tail(NULL),
222 _inc_cset_bytes_used_before(0),
223 _inc_cset_max_finger(NULL),
224 _inc_cset_recorded_rs_lengths(0),
225 _inc_cset_recorded_rs_lengths_diffs(0),
226 _inc_cset_predicted_elapsed_time_ms(0.0),
227 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
228
229 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
230 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
231 #endif // _MSC_VER
232
233 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
234 G1YoungSurvRateNumRegionsSummary)),
235 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
236 G1YoungSurvRateNumRegionsSummary)),
237 // add here any more surv rate groups
238 _recorded_survivor_regions(0),
239 _recorded_survivor_head(NULL),
240 _recorded_survivor_tail(NULL),
241 _survivors_age_table(true),
242
243 _gc_overhead_perc(0.0) {
244
245 // Set up the region size and associated fields. Given that the
246 // policy is created before the heap, we have to set this up here,
247 // so it's done as soon as possible.
248 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
249 HeapRegionRemSet::setup_remset_size();
250
251 G1ErgoVerbose::initialize();
252 if (PrintAdaptiveSizePolicy) {
253 // Currently, we only use a single switch for all the heuristics.
254 G1ErgoVerbose::set_enabled(true);
255 // Given that we don't currently have a verboseness level
256 // parameter, we'll hardcode this to high. This can be easily
257 // changed in the future.
258 G1ErgoVerbose::set_level(ErgoHigh);
259 } else {
260 G1ErgoVerbose::set_enabled(false);
261 }
262
263 // Verify PLAB sizes
264 const size_t region_size = HeapRegion::GrainWords;
265 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
266 char buffer[128];
267 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
268 OldPLABSize > region_size ? "Old" : "Young", region_size);
269 vm_exit_during_initialization(buffer);
270 }
271
272 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
273 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
274
275 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
276 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
277 _par_last_satb_filtering_times_ms = new double[_parallel_gc_threads];
278
279 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
280 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
281
282 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
283
284 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
285
286 _par_last_termination_times_ms = new double[_parallel_gc_threads];
287 _par_last_termination_attempts = new double[_parallel_gc_threads];
288 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
289 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
290 _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
291
292 int index;
293 if (ParallelGCThreads == 0)
294 index = 0;
295 else if (ParallelGCThreads > 8)
296 index = 7;
297 else
298 index = ParallelGCThreads - 1;
299
300 _pending_card_diff_seq->add(0.0);
301 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
302 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
303 _young_cards_per_entry_ratio_seq->add(
304 young_cards_per_entry_ratio_defaults[index]);
305 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
306 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
307 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
308 _young_other_cost_per_region_ms_seq->add(
309 young_other_cost_per_region_ms_defaults[index]);
310 _non_young_other_cost_per_region_ms_seq->add(
311 non_young_other_cost_per_region_ms_defaults[index]);
312
313 // Below, we might need to calculate the pause time target based on
314 // the pause interval. When we do so we are going to give G1 maximum
315 // flexibility and allow it to do pauses when it needs to. So, we'll
316 // arrange that the pause interval to be pause time target + 1 to
317 // ensure that a) the pause time target is maximized with respect to
318 // the pause interval and b) we maintain the invariant that pause
319 // time target < pause interval. If the user does not want this
320 // maximum flexibility, they will have to set the pause interval
321 // explicitly.
322
323 // First make sure that, if either parameter is set, its value is
324 // reasonable.
325 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
326 if (MaxGCPauseMillis < 1) {
327 vm_exit_during_initialization("MaxGCPauseMillis should be "
328 "greater than 0");
329 }
330 }
331 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
332 if (GCPauseIntervalMillis < 1) {
333 vm_exit_during_initialization("GCPauseIntervalMillis should be "
334 "greater than 0");
335 }
336 }
337
338 // Then, if the pause time target parameter was not set, set it to
339 // the default value.
340 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
341 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
342 // The default pause time target in G1 is 200ms
343 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
344 } else {
345 // We do not allow the pause interval to be set without the
346 // pause time target
347 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
348 "without setting MaxGCPauseMillis");
349 }
350 }
351
352 // Then, if the interval parameter was not set, set it according to
353 // the pause time target (this will also deal with the case when the
354 // pause time target is the default value).
355 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
356 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
357 }
358
359 // Finally, make sure that the two parameters are consistent.
360 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
361 char buffer[256];
362 jio_snprintf(buffer, 256,
363 "MaxGCPauseMillis (%u) should be less than "
364 "GCPauseIntervalMillis (%u)",
365 MaxGCPauseMillis, GCPauseIntervalMillis);
366 vm_exit_during_initialization(buffer);
367 }
368
369 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
370 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
371 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
372 _sigma = (double) G1ConfidencePercent / 100.0;
373
374 // start conservatively (around 50ms is about right)
375 _concurrent_mark_remark_times_ms->add(0.05);
376 _concurrent_mark_cleanup_times_ms->add(0.20);
377 _tenuring_threshold = MaxTenuringThreshold;
378 // _max_survivor_regions will be calculated by
379 // update_young_list_target_length() during initialization.
380 _max_survivor_regions = 0;
381
382 assert(GCTimeRatio > 0,
383 "we should have set it to a default value set_g1_gc_flags() "
384 "if a user set it to 0");
385 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
386
387 uintx reserve_perc = G1ReservePercent;
388 // Put an artificial ceiling on this so that it's not set to a silly value.
389 if (reserve_perc > 50) {
390 reserve_perc = 50;
391 warning("G1ReservePercent is set to a value that is too large, "
392 "it's been updated to %u", reserve_perc);
393 }
394 _reserve_factor = (double) reserve_perc / 100.0;
395 // This will be set when the heap is expanded
396 // for the first time during initialization.
397 _reserve_regions = 0;
398
399 initialize_all();
400 _collectionSetChooser = new CollectionSetChooser();
401 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
402 }
403
404 void G1CollectorPolicy::initialize_flags() {
405 set_min_alignment(HeapRegion::GrainBytes);
406 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
407 if (SurvivorRatio < 1) {
408 vm_exit_during_initialization("Invalid survivor ratio specified");
409 }
410 CollectorPolicy::initialize_flags();
411 }
412
413 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
414 assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");
415 assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");
416 assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");
417
418 if (FLAG_IS_CMDLINE(NewRatio)) {
419 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
420 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
421 } else {
422 _sizer_kind = SizerNewRatio;
423 _adaptive_size = false;
424 return;
425 }
426 }
427
428 if (FLAG_IS_CMDLINE(NewSize)) {
429 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
430 1U);
431 if (FLAG_IS_CMDLINE(MaxNewSize)) {
432 _max_desired_young_length =
433 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
434 1U);
435 _sizer_kind = SizerMaxAndNewSize;
436 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
437 } else {
438 _sizer_kind = SizerNewSizeOnly;
439 }
440 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
441 _max_desired_young_length =
442 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
443 1U);
444 _sizer_kind = SizerMaxNewSizeOnly;
445 }
446 }
447
448 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
449 uint default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;
450 return MAX2(1U, default_value);
451 }
452
453 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
454 uint default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;
455 return MAX2(1U, default_value);
456 }
457
458 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
459 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
460
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 }
484
485 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
486 }
487
488 void G1CollectorPolicy::init() {
489 // Set aside an initial future to_space.
490 _g1 = G1CollectedHeap::heap();
491
492 assert(Heap_lock->owned_by_self(), "Locking discipline.");
493
494 initialize_gc_policy_counters();
495
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;
504
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 }
509
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 }
514
515 bool G1CollectorPolicy::predict_will_fit(uint young_length,
516 double base_time_ms,
517 uint 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 }
523
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 }
534
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 }
541
542 // success!
543 return true;
544 }
545
546 void G1CollectorPolicy::record_new_heap_size(uint 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 = (uint) ceil(reserve_regions_d);
552
553 _young_gen_sizer->heap_size_changed(new_number_of_regions);
554 }
555
556 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
557 uint base_min_length) {
558 uint 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 = (uint) 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 }
573
574 uint 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 }
580
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 }
587
588 // Calculate the absolute and desired min bounds.
589
590 // This is how many young regions we already have (currently: the survivors).
591 uint 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 uint absolute_min_length = base_min_length + 1;
595 uint 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 }
600
601 // Calculate the absolute and desired max bounds.
602
603 // We will try our best not to "eat" into the reserve.
604 uint 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 uint 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 }
612
613 uint 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 }
632
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 }
642
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;
647
648 update_max_gc_locker_expansion();
649 }
650
651 uint
652 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
653 uint base_min_length,
654 uint desired_min_length,
655 uint desired_max_length) {
656 assert(adaptive_young_list_length(), "pre-condition");
657 assert(gcs_are_young(), "only call this for young GCs");
658
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 }
663
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 uint min_young_length = desired_min_length - base_min_length;
671 assert(desired_max_length > base_min_length, "invariant");
672 uint max_young_length = desired_max_length - base_min_length;
673
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 uint available_free_regions = _free_regions_at_end_of_collection;
683 uint base_free_regions = 0;
684 if (available_free_regions > _reserve_regions) {
685 base_free_regions = available_free_regions - _reserve_regions;
686 }
687
688 // Here, we will make sure that the shortest young length that
689 // makes sense fits within the target pause time.
690
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.
718
719 assert(min_young_length < max_young_length, "invariant");
720 uint diff = (max_young_length - min_young_length) / 2;
721 while (diff > 0) {
722 uint 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.
734
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 }
754
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 }
764
765 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
766 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
767
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 }
775
776
777
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 }
784
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 }
792
793
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 }
801
802 bool
803 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
804 SurvRateGroup *surv_rate_group) {
805 guarantee( surv_rate_group != NULL, "pre-condition" );
806
807 const char* name = surv_rate_group->name();
808 bool ret = true;
809 int prev_age = -1;
810
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 }
819
820 if (surv_rate_group == group) {
821 int age = curr->age_in_surv_rate_group();
822
823 if (age < 0) {
824 gclog_or_tty->print_cr("## %s: encountered negative age", name);
825 ret = false;
826 }
827
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 }
836
837 return ret;
838 }
839 #endif // PRODUCT
840
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 }
846
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;
853
854 _all_full_gc_times_ms->add(full_gc_time_ms);
855
856 update_recent_gc_times(end_sec, full_gc_time_ms);
857
858 _g1->clear_full_collection();
859
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 _in_marking_window = false;
867 _in_marking_window_im = false;
868
869 _short_lived_surv_rate_group->start_adding_regions();
870 // also call this on any additional surv rate groups
871
872 record_survivor_regions(0, NULL, NULL);
873
874 _free_regions_at_end_of_collection = _g1->free_regions();
875 // Reset survivors SurvRateGroup.
876 _survivor_surv_rate_group->reset();
877 update_young_list_target_length();
878 _collectionSetChooser->clear();
879 }
880
881 void G1CollectorPolicy::record_stop_world_start() {
882 _stop_world_start = os::elapsedTime();
883 }
884
885 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
886 size_t start_used) {
887 if (G1Log::finer()) {
888 gclog_or_tty->print("[%s", GCCauseString("GC pause", _g1->gc_cause())
889 .append(gcs_are_young() ? " (young)" : " (mixed)"));
890 }
891
892 // We only need to do this here as the policy will only be applied
893 // to the GC we're about to start. so, no point is calculating this
894 // every time we calculate / recalculate the target young length.
895 update_survivors_policy();
896
897 assert(_g1->used() == _g1->recalculate_used(),
898 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
899 _g1->used(), _g1->recalculate_used()));
900
901 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
902 _all_stop_world_times_ms->add(s_w_t_ms);
903 _stop_world_start = 0.0;
904
905 _cur_collection_start_sec = start_time_sec;
906 _cur_collection_pause_used_at_start_bytes = start_used;
907 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
908 _pending_cards = _g1->pending_card_num();
909 _max_pending_cards = _g1->max_pending_card_num();
910
911 _bytes_in_collection_set_before_gc = 0;
912 _bytes_copied_during_gc = 0;
913
914 YoungList* young_list = _g1->young_list();
915 _eden_bytes_before_gc = young_list->eden_used_bytes();
916 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
917 _capacity_before_gc = _g1->capacity();
918
919 #ifdef DEBUG
920 // initialise these to something well known so that we can spot
921 // if they are not set properly
922
923 for (int i = 0; i < _parallel_gc_threads; ++i) {
924 _par_last_gc_worker_start_times_ms[i] = -1234.0;
925 _par_last_ext_root_scan_times_ms[i] = -1234.0;
926 _par_last_satb_filtering_times_ms[i] = -1234.0;
927 _par_last_update_rs_times_ms[i] = -1234.0;
928 _par_last_update_rs_processed_buffers[i] = -1234.0;
929 _par_last_scan_rs_times_ms[i] = -1234.0;
930 _par_last_obj_copy_times_ms[i] = -1234.0;
931 _par_last_termination_times_ms[i] = -1234.0;
932 _par_last_termination_attempts[i] = -1234.0;
933 _par_last_gc_worker_end_times_ms[i] = -1234.0;
934 _par_last_gc_worker_times_ms[i] = -1234.0;
935 _par_last_gc_worker_other_times_ms[i] = -1234.0;
936 }
937 #endif
938
939 for (int i = 0; i < _aux_num; ++i) {
940 _cur_aux_times_ms[i] = 0.0;
941 _cur_aux_times_set[i] = false;
942 }
943
944 // This is initialized to zero here and is set during the evacuation
945 // pause if we actually waited for the root region scanning to finish.
946 _root_region_scan_wait_time_ms = 0.0;
947
948 _last_gc_was_young = false;
949
950 // do that for any other surv rate groups
951 _short_lived_surv_rate_group->stop_adding_regions();
952 _survivors_age_table.clear();
953
954 assert( verify_young_ages(), "region age verification" );
955 }
956
957 void G1CollectorPolicy::record_concurrent_mark_init_end(double
958 mark_init_elapsed_time_ms) {
959 _during_marking = true;
960 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
961 clear_during_initial_mark_pause();
962 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
963 }
964
965 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
966 _mark_remark_start_sec = os::elapsedTime();
967 _during_marking = false;
968 }
969
970 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
971 double end_time_sec = os::elapsedTime();
972 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
973 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
974 _cur_mark_stop_world_time_ms += elapsed_time_ms;
975 _prev_collection_pause_end_ms += elapsed_time_ms;
976
977 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
978 }
979
980 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
981 _mark_cleanup_start_sec = os::elapsedTime();
982 }
983
984 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
985 _last_young_gc = true;
986 _in_marking_window = false;
987 }
988
989 void G1CollectorPolicy::record_concurrent_pause() {
990 if (_stop_world_start > 0.0) {
991 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
992 _all_yield_times_ms->add(yield_ms);
993 }
994 }
995
996 void G1CollectorPolicy::record_concurrent_pause_end() {
997 }
998
999 template<class T>
1000 T sum_of(T* sum_arr, int start, int n, int N) {
1001 T sum = (T)0;
1002 for (int i = 0; i < n; i++) {
1003 int j = (start + i) % N;
1004 sum += sum_arr[j];
1005 }
1006 return sum;
1007 }
1008
1009 void G1CollectorPolicy::print_par_stats(int level,
1010 const char* str,
1011 double* data) {
1012 double min = data[0], max = data[0];
1013 double total = 0.0;
1014 LineBuffer buf(level);
1015 buf.append("[%s (ms):", str);
1016 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1017 double val = data[i];
1018 if (val < min)
1019 min = val;
1020 if (val > max)
1021 max = val;
1022 total += val;
1023 if (G1Log::finest()) {
1024 buf.append(" %.1lf", val);
1025 }
1026 }
1027
1028 if (G1Log::finest()) {
1029 buf.append_and_print_cr("");
1030 }
1031 double avg = total / (double) no_of_gc_threads();
1032 buf.append_and_print_cr(" Avg: %.1lf Min: %.1lf Max: %.1lf Diff: %.1lf]",
1033 avg, min, max, max - min);
1034 }
1035
1036 void G1CollectorPolicy::print_par_sizes(int level,
1037 const char* str,
1038 double* data) {
1039 double min = data[0], max = data[0];
1040 double total = 0.0;
1041 LineBuffer buf(level);
1042 buf.append("[%s :", str);
1043 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1044 double val = data[i];
1045 if (val < min)
1046 min = val;
1047 if (val > max)
1048 max = val;
1049 total += val;
1050 buf.append(" %d", (int) val);
1051 }
1052 buf.append_and_print_cr("");
1053 double avg = total / (double) no_of_gc_threads();
1054 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1055 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1056 }
1057
1058 void G1CollectorPolicy::print_stats(int level,
1059 const char* str,
1060 double value) {
1061 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1062 }
1063
1064 void G1CollectorPolicy::print_stats(int level,
1065 const char* str,
1066 int value) {
1067 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1068 }
1069
1070 double G1CollectorPolicy::avg_value(double* data) {
1071 if (G1CollectedHeap::use_parallel_gc_threads()) {
1072 double ret = 0.0;
1073 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1074 ret += data[i];
1075 }
1076 return ret / (double) no_of_gc_threads();
1077 } else {
1078 return data[0];
1079 }
1080 }
1081
1082 double G1CollectorPolicy::max_value(double* data) {
1083 if (G1CollectedHeap::use_parallel_gc_threads()) {
1084 double ret = data[0];
1085 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1086 if (data[i] > ret) {
1087 ret = data[i];
1088 }
1089 }
1090 return ret;
1091 } else {
1092 return data[0];
1093 }
1094 }
1095
1096 double G1CollectorPolicy::sum_of_values(double* data) {
1097 if (G1CollectedHeap::use_parallel_gc_threads()) {
1098 double sum = 0.0;
1099 for (uint i = 0; i < no_of_gc_threads(); i++) {
1100 sum += data[i];
1101 }
1102 return sum;
1103 } else {
1104 return data[0];
1105 }
1106 }
1107
1108 double G1CollectorPolicy::max_sum(double* data1, double* data2) {
1109 double ret = data1[0] + data2[0];
1110
1111 if (G1CollectedHeap::use_parallel_gc_threads()) {
1112 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1113 double data = data1[i] + data2[i];
1114 if (data > ret) {
1115 ret = data;
1116 }
1117 }
1118 }
1119 return ret;
1120 }
1121
1122 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
1123 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
1124 return false;
1125 }
1126
1127 size_t marking_initiating_used_threshold =
1128 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1129 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
1130 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
1131
1132 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
1133 if (gcs_are_young()) {
1134 ergo_verbose5(ErgoConcCycles,
1135 "request concurrent cycle initiation",
1136 ergo_format_reason("occupancy higher than threshold")
1137 ergo_format_byte("occupancy")
1138 ergo_format_byte("allocation request")
1139 ergo_format_byte_perc("threshold")
1140 ergo_format_str("source"),
1141 cur_used_bytes,
1142 alloc_byte_size,
1143 marking_initiating_used_threshold,
1144 (double) InitiatingHeapOccupancyPercent,
1145 source);
1146 return true;
1147 } else {
1148 ergo_verbose5(ErgoConcCycles,
1149 "do not request concurrent cycle initiation",
1150 ergo_format_reason("still doing mixed collections")
1151 ergo_format_byte("occupancy")
1152 ergo_format_byte("allocation request")
1153 ergo_format_byte_perc("threshold")
1154 ergo_format_str("source"),
1155 cur_used_bytes,
1156 alloc_byte_size,
1157 marking_initiating_used_threshold,
1158 (double) InitiatingHeapOccupancyPercent,
1159 source);
1160 }
1161 }
1162
1163 return false;
1164 }
1165
1166 // Anything below that is considered to be zero
1167 #define MIN_TIMER_GRANULARITY 0.0000001
1168
1169 void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
1170 double end_time_sec = os::elapsedTime();
1171 double elapsed_ms = _last_pause_time_ms;
1172 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1173 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1174 "otherwise, the subtraction below does not make sense");
1175 size_t rs_size =
1176 _cur_collection_pause_used_regions_at_start - cset_region_length();
1177 size_t cur_used_bytes = _g1->used();
1178 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1179 bool last_pause_included_initial_mark = false;
1180 bool update_stats = !_g1->evacuation_failed();
1181 set_no_of_gc_threads(no_of_gc_threads);
1182
1183 #ifndef PRODUCT
1184 if (G1YoungSurvRateVerbose) {
1185 gclog_or_tty->print_cr("");
1186 _short_lived_surv_rate_group->print();
1187 // do that for any other surv rate groups too
1188 }
1189 #endif // PRODUCT
1190
1191 last_pause_included_initial_mark = during_initial_mark_pause();
1192 if (last_pause_included_initial_mark) {
1193 record_concurrent_mark_init_end(0.0);
1194 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
1195 // Note: this might have already been set, if during the last
1196 // pause we decided to start a cycle but at the beginning of
1197 // this pause we decided to postpone it. That's OK.
1198 set_initiate_conc_mark_if_possible();
1199 }
1200
1201 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1202 end_time_sec, false);
1203
1204 // This assert is exempted when we're doing parallel collection pauses,
1205 // because the fragmentation caused by the parallel GC allocation buffers
1206 // can lead to more memory being used during collection than was used
1207 // before. Best leave this out until the fragmentation problem is fixed.
1208 // Pauses in which evacuation failed can also lead to negative
1209 // collections, since no space is reclaimed from a region containing an
1210 // object whose evacuation failed.
1211 // Further, we're now always doing parallel collection. But I'm still
1212 // leaving this here as a placeholder for a more precise assertion later.
1213 // (DLD, 10/05.)
1214 assert((true || parallel) // Always using GC LABs now.
1215 || _g1->evacuation_failed()
1216 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1217 "Negative collection");
1218
1219 size_t freed_bytes =
1220 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1221 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1222
1223 double survival_fraction =
1224 (double)surviving_bytes/
1225 (double)_collection_set_bytes_used_before;
1226
1227 // These values are used to update the summary information that is
1228 // displayed when TraceGen0Time is enabled, and are output as part
1229 // of the "finer" output, in the non-parallel case.
1230
1231 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1232 double satb_filtering_time = avg_value(_par_last_satb_filtering_times_ms);
1233 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1234 double update_rs_processed_buffers =
1235 sum_of_values(_par_last_update_rs_processed_buffers);
1236 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1237 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1238 double termination_time = avg_value(_par_last_termination_times_ms);
1239
1240 double known_time = ext_root_scan_time +
1241 satb_filtering_time +
1242 update_rs_time +
1243 scan_rs_time +
1244 obj_copy_time;
1245
1246 double other_time_ms = elapsed_ms;
1247
1248 // Subtract the root region scanning wait time. It's initialized to
1249 // zero at the start of the pause.
1250 other_time_ms -= _root_region_scan_wait_time_ms;
1251
1252 if (parallel) {
1253 other_time_ms -= _cur_collection_par_time_ms;
1254 } else {
1255 other_time_ms -= known_time;
1256 }
1257
1258 // Now subtract the time taken to fix up roots in generated code
1259 other_time_ms -= _cur_collection_code_root_fixup_time_ms;
1260
1261 // Subtract the time taken to clean the card table from the
1262 // current value of "other time"
1263 other_time_ms -= _cur_clear_ct_time_ms;
1264
1265 // TraceGen0Time and TraceGen1Time summary info updating.
1266 _all_pause_times_ms->add(elapsed_ms);
1267
1268 if (update_stats) {
1269 _summary->record_total_time_ms(elapsed_ms);
1270 _summary->record_other_time_ms(other_time_ms);
1271
1272 MainBodySummary* body_summary = _summary->main_body_summary();
1273 assert(body_summary != NULL, "should not be null!");
1274
1275 body_summary->record_root_region_scan_wait_time_ms(
1276 _root_region_scan_wait_time_ms);
1277 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1278 body_summary->record_satb_filtering_time_ms(satb_filtering_time);
1279 body_summary->record_update_rs_time_ms(update_rs_time);
1280 body_summary->record_scan_rs_time_ms(scan_rs_time);
1281 body_summary->record_obj_copy_time_ms(obj_copy_time);
1282
1283 if (parallel) {
1284 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1285 body_summary->record_termination_time_ms(termination_time);
1286
1287 double parallel_known_time = known_time + termination_time;
1288 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1289 body_summary->record_parallel_other_time_ms(parallel_other_time);
1290 }
1291
1292 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1293
1294 // We exempt parallel collection from this check because Alloc Buffer
1295 // fragmentation can produce negative collections. Same with evac
1296 // failure.
1297 // Further, we're now always doing parallel collection. But I'm still
1298 // leaving this here as a placeholder for a more precise assertion later.
1299 // (DLD, 10/05.
1300 assert((true || parallel)
1301 || _g1->evacuation_failed()
1302 || surviving_bytes <= _collection_set_bytes_used_before,
1303 "Or else negative collection!");
1304
1305 // this is where we update the allocation rate of the application
1306 double app_time_ms =
1307 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1308 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1309 // This usually happens due to the timer not having the required
1310 // granularity. Some Linuxes are the usual culprits.
1311 // We'll just set it to something (arbitrarily) small.
1312 app_time_ms = 1.0;
1313 }
1314 // We maintain the invariant that all objects allocated by mutator
1315 // threads will be allocated out of eden regions. So, we can use
1316 // the eden region number allocated since the previous GC to
1317 // calculate the application's allocate rate. The only exception
1318 // to that is humongous objects that are allocated separately. But
1319 // given that humongous object allocations do not really affect
1320 // either the pause's duration nor when the next pause will take
1321 // place we can safely ignore them here.
1322 uint regions_allocated = eden_cset_region_length();
1323 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1324 _alloc_rate_ms_seq->add(alloc_rate_ms);
1325
1326 double interval_ms =
1327 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1328 update_recent_gc_times(end_time_sec, elapsed_ms);
1329 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1330 if (recent_avg_pause_time_ratio() < 0.0 ||
1331 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1332 #ifndef PRODUCT
1333 // Dump info to allow post-facto debugging
1334 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1335 gclog_or_tty->print_cr("-------------------------------------------");
1336 gclog_or_tty->print_cr("Recent GC Times (ms):");
1337 _recent_gc_times_ms->dump();
1338 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1339 _recent_prev_end_times_for_all_gcs_sec->dump();
1340 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1341 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1342 // In debug mode, terminate the JVM if the user wants to debug at this point.
1343 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1344 #endif // !PRODUCT
1345 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1346 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1347 if (_recent_avg_pause_time_ratio < 0.0) {
1348 _recent_avg_pause_time_ratio = 0.0;
1349 } else {
1350 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1351 _recent_avg_pause_time_ratio = 1.0;
1352 }
1353 }
1354 }
1355
1356 for (int i = 0; i < _aux_num; ++i) {
1357 if (_cur_aux_times_set[i]) {
1358 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1359 }
1360 }
1361
1362 if (G1Log::finer()) {
1363 bool print_marking_info =
1364 _g1->mark_in_progress() && !last_pause_included_initial_mark;
1365
1366 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1367 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1368 elapsed_ms / 1000.0);
1369
1370 if (_root_region_scan_wait_time_ms > 0.0) {
1371 print_stats(1, "Root Region Scan Waiting", _root_region_scan_wait_time_ms);
1372 }
1373 if (parallel) {
1374 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1375 print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
1376 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1377 if (print_marking_info) {
1378 print_par_stats(2, "SATB Filtering", _par_last_satb_filtering_times_ms);
1379 }
1380 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1381 if (G1Log::finest()) {
1382 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1383 }
1384 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1385 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1386 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1387 if (G1Log::finest()) {
1388 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1389 }
1390
1391 for (int i = 0; i < _parallel_gc_threads; i++) {
1392 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] -
1393 _par_last_gc_worker_start_times_ms[i];
1394
1395 double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
1396 _par_last_satb_filtering_times_ms[i] +
1397 _par_last_update_rs_times_ms[i] +
1398 _par_last_scan_rs_times_ms[i] +
1399 _par_last_obj_copy_times_ms[i] +
1400 _par_last_termination_times_ms[i];
1401
1402 _par_last_gc_worker_other_times_ms[i] = _par_last_gc_worker_times_ms[i] -
1403 worker_known_time;
1404 }
1405
1406 print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
1407 print_par_stats(2, "GC Worker Total", _par_last_gc_worker_times_ms);
1408 print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
1409 } else {
1410 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1411 if (print_marking_info) {
1412 print_stats(1, "SATB Filtering", satb_filtering_time);
1413 }
1414 print_stats(1, "Update RS", update_rs_time);
1415 if (G1Log::finest()) {
1416 print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
1417 }
1418 print_stats(1, "Scan RS", scan_rs_time);
1419 print_stats(1, "Object Copying", obj_copy_time);
1420 }
1421 print_stats(1, "Code Root Fixup", _cur_collection_code_root_fixup_time_ms);
1422 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1423 #ifndef PRODUCT
1424 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1425 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1426 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1427 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1428 if (_num_cc_clears > 0) {
1429 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1430 }
1431 #endif
1432 print_stats(1, "Other", other_time_ms);
1433 print_stats(2, "Choose CSet",
1434 (_recorded_young_cset_choice_time_ms +
1435 _recorded_non_young_cset_choice_time_ms));
1436 print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
1437 print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
1438 print_stats(2, "Free CSet",
1439 (_recorded_young_free_cset_time_ms +
1440 _recorded_non_young_free_cset_time_ms));
1441
1442 for (int i = 0; i < _aux_num; ++i) {
1443 if (_cur_aux_times_set[i]) {
1444 char buffer[96];
1445 sprintf(buffer, "Aux%d", i);
1446 print_stats(1, buffer, _cur_aux_times_ms[i]);
1447 }
1448 }
1449 }
1450
1451 bool new_in_marking_window = _in_marking_window;
1452 bool new_in_marking_window_im = false;
1453 if (during_initial_mark_pause()) {
1454 new_in_marking_window = true;
1455 new_in_marking_window_im = true;
1456 }
1457
1458 if (_last_young_gc) {
1459 // This is supposed to to be the "last young GC" before we start
1460 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1461
1462 if (!last_pause_included_initial_mark) {
1463 if (next_gc_should_be_mixed("start mixed GCs",
1464 "do not start mixed GCs")) {
1465 set_gcs_are_young(false);
1466 }
1467 } else {
1468 ergo_verbose0(ErgoMixedGCs,
1469 "do not start mixed GCs",
1470 ergo_format_reason("concurrent cycle is about to start"));
1471 }
1472 _last_young_gc = false;
1473 }
1474
1475 if (!_last_gc_was_young) {
1476 // This is a mixed GC. Here we decide whether to continue doing
1477 // mixed GCs or not.
1478
1479 if (!next_gc_should_be_mixed("continue mixed GCs",
1480 "do not continue mixed GCs")) {
1481 set_gcs_are_young(true);
1482 }
1483 }
1484
1485 _short_lived_surv_rate_group->start_adding_regions();
1486 // do that for any other surv rate groupsx
1487
1488 if (update_stats) {
1489 double pause_time_ms = elapsed_ms;
1490
1491 size_t diff = 0;
1492 if (_max_pending_cards >= _pending_cards) {
1493 diff = _max_pending_cards - _pending_cards;
1494 }
1495 _pending_card_diff_seq->add((double) diff);
1496
1497 double cost_per_card_ms = 0.0;
1498 if (_pending_cards > 0) {
1499 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1500 _cost_per_card_ms_seq->add(cost_per_card_ms);
1501 }
1502
1503 size_t cards_scanned = _g1->cards_scanned();
1504
1505 double cost_per_entry_ms = 0.0;
1506 if (cards_scanned > 10) {
1507 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1508 if (_last_gc_was_young) {
1509 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1510 } else {
1511 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1512 }
1513 }
1514
1515 if (_max_rs_lengths > 0) {
1516 double cards_per_entry_ratio =
1517 (double) cards_scanned / (double) _max_rs_lengths;
1518 if (_last_gc_was_young) {
1519 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1520 } else {
1521 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1522 }
1523 }
1524
1525 // This is defensive. For a while _max_rs_lengths could get
1526 // smaller than _recorded_rs_lengths which was causing
1527 // rs_length_diff to get very large and mess up the RSet length
1528 // predictions. The reason was unsafe concurrent updates to the
1529 // _inc_cset_recorded_rs_lengths field which the code below guards
1530 // against (see CR 7118202). This bug has now been fixed (see CR
1531 // 7119027). However, I'm still worried that
1532 // _inc_cset_recorded_rs_lengths might still end up somewhat
1533 // inaccurate. The concurrent refinement thread calculates an
1534 // RSet's length concurrently with other CR threads updating it
1535 // which might cause it to calculate the length incorrectly (if,
1536 // say, it's in mid-coarsening). So I'll leave in the defensive
1537 // conditional below just in case.
1538 size_t rs_length_diff = 0;
1539 if (_max_rs_lengths > _recorded_rs_lengths) {
1540 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1541 }
1542 _rs_length_diff_seq->add((double) rs_length_diff);
1543
1544 size_t copied_bytes = surviving_bytes;
1545 double cost_per_byte_ms = 0.0;
1546 if (copied_bytes > 0) {
1547 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1548 if (_in_marking_window) {
1549 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1550 } else {
1551 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1552 }
1553 }
1554
1555 double all_other_time_ms = pause_time_ms -
1556 (update_rs_time + scan_rs_time + obj_copy_time + termination_time);
1557
1558 double young_other_time_ms = 0.0;
1559 if (young_cset_region_length() > 0) {
1560 young_other_time_ms =
1561 _recorded_young_cset_choice_time_ms +
1562 _recorded_young_free_cset_time_ms;
1563 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1564 (double) young_cset_region_length());
1565 }
1566 double non_young_other_time_ms = 0.0;
1567 if (old_cset_region_length() > 0) {
1568 non_young_other_time_ms =
1569 _recorded_non_young_cset_choice_time_ms +
1570 _recorded_non_young_free_cset_time_ms;
1571
1572 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1573 (double) old_cset_region_length());
1574 }
1575
1576 double constant_other_time_ms = all_other_time_ms -
1577 (young_other_time_ms + non_young_other_time_ms);
1578 _constant_other_time_ms_seq->add(constant_other_time_ms);
1579
1580 double survival_ratio = 0.0;
1581 if (_bytes_in_collection_set_before_gc > 0) {
1582 survival_ratio = (double) _bytes_copied_during_gc /
1583 (double) _bytes_in_collection_set_before_gc;
1584 }
1585
1586 _pending_cards_seq->add((double) _pending_cards);
1587 _rs_lengths_seq->add((double) _max_rs_lengths);
1588 }
1589
1590 _in_marking_window = new_in_marking_window;
1591 _in_marking_window_im = new_in_marking_window_im;
1592 _free_regions_at_end_of_collection = _g1->free_regions();
1593 update_young_list_target_length();
1594
1595 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1596 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1597 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1598
1599 _collectionSetChooser->verify();
1600 }
1601
1602 #define EXT_SIZE_FORMAT "%d%s"
1603 #define EXT_SIZE_PARAMS(bytes) \
1604 byte_size_in_proper_unit((bytes)), \
1605 proper_unit_for_byte_size((bytes))
1606
1607 void G1CollectorPolicy::print_heap_transition() {
1608 if (G1Log::finer()) {
1609 YoungList* young_list = _g1->young_list();
1610 size_t eden_bytes = young_list->eden_used_bytes();
1611 size_t survivor_bytes = young_list->survivor_used_bytes();
1612 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1613 size_t used = _g1->used();
1614 size_t capacity = _g1->capacity();
1615 size_t eden_capacity =
1616 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1617
1618 gclog_or_tty->print_cr(
1619 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1620 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1621 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1622 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1623 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1624 EXT_SIZE_PARAMS(_prev_eden_capacity),
1625 EXT_SIZE_PARAMS(eden_bytes),
1626 EXT_SIZE_PARAMS(eden_capacity),
1627 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1628 EXT_SIZE_PARAMS(survivor_bytes),
1629 EXT_SIZE_PARAMS(used_before_gc),
1630 EXT_SIZE_PARAMS(_capacity_before_gc),
1631 EXT_SIZE_PARAMS(used),
1632 EXT_SIZE_PARAMS(capacity));
1633
1634 _prev_eden_capacity = eden_capacity;
1635 } else if (G1Log::fine()) {
1636 _g1->print_size_transition(gclog_or_tty,
1637 _cur_collection_pause_used_at_start_bytes,
1638 _g1->used(), _g1->capacity());
1639 }
1640 }
1641
1642 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1643 double update_rs_processed_buffers,
1644 double goal_ms) {
1645 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1646 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1647
1648 if (G1UseAdaptiveConcRefinement) {
1649 const int k_gy = 3, k_gr = 6;
1650 const double inc_k = 1.1, dec_k = 0.9;
1651
1652 int g = cg1r->green_zone();
1653 if (update_rs_time > goal_ms) {
1654 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1655 } else {
1656 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1657 g = (int)MAX2(g * inc_k, g + 1.0);
1658 }
1659 }
1660 // Change the refinement threads params
1661 cg1r->set_green_zone(g);
1662 cg1r->set_yellow_zone(g * k_gy);
1663 cg1r->set_red_zone(g * k_gr);
1664 cg1r->reinitialize_threads();
1665
1666 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1667 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1668 cg1r->yellow_zone());
1669 // Change the barrier params
1670 dcqs.set_process_completed_threshold(processing_threshold);
1671 dcqs.set_max_completed_queue(cg1r->red_zone());
1672 }
1673
1674 int curr_queue_size = dcqs.completed_buffers_num();
1675 if (curr_queue_size >= cg1r->yellow_zone()) {
1676 dcqs.set_completed_queue_padding(curr_queue_size);
1677 } else {
1678 dcqs.set_completed_queue_padding(0);
1679 }
1680 dcqs.notify_if_necessary();
1681 }
1682
1683 double
1684 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1685 size_t rs_length = predict_rs_length_diff();
1686 size_t card_num;
1687 if (gcs_are_young()) {
1688 card_num = predict_young_card_num(rs_length);
1689 } else {
1690 card_num = predict_non_young_card_num(rs_length);
1691 }
1692 return predict_base_elapsed_time_ms(pending_cards, card_num);
1693 }
1694
1695 double
1696 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1697 size_t scanned_cards) {
1698 return
1699 predict_rs_update_time_ms(pending_cards) +
1700 predict_rs_scan_time_ms(scanned_cards) +
1701 predict_constant_other_time_ms();
1702 }
1703
1704 double
1705 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1706 bool young) {
1707 size_t rs_length = hr->rem_set()->occupied();
1708 size_t card_num;
1709 if (gcs_are_young()) {
1710 card_num = predict_young_card_num(rs_length);
1711 } else {
1712 card_num = predict_non_young_card_num(rs_length);
1713 }
1714 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1715
1716 double region_elapsed_time_ms =
1717 predict_rs_scan_time_ms(card_num) +
1718 predict_object_copy_time_ms(bytes_to_copy);
1719
1720 if (young)
1721 region_elapsed_time_ms += predict_young_other_time_ms(1);
1722 else
1723 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1724
1725 return region_elapsed_time_ms;
1726 }
1727
1728 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1729 size_t bytes_to_copy;
1730 if (hr->is_marked())
1731 bytes_to_copy = hr->max_live_bytes();
1732 else {
1733 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1734 int age = hr->age_in_surv_rate_group();
1735 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1736 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1737 }
1738 return bytes_to_copy;
1739 }
1740
1741 void
1742 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1743 uint survivor_cset_region_length) {
1744 _eden_cset_region_length = eden_cset_region_length;
1745 _survivor_cset_region_length = survivor_cset_region_length;
1746 _old_cset_region_length = 0;
1747 }
1748
1749 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1750 _recorded_rs_lengths = rs_lengths;
1751 }
1752
1753 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1754 double elapsed_ms) {
1755 _recent_gc_times_ms->add(elapsed_ms);
1756 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1757 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1758 }
1759
1760 size_t G1CollectorPolicy::expansion_amount() {
1761 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1762 double threshold = _gc_overhead_perc;
1763 if (recent_gc_overhead > threshold) {
1764 // We will double the existing space, or take
1765 // G1ExpandByPercentOfAvailable % of the available expansion
1766 // space, whichever is smaller, bounded below by a minimum
1767 // expansion (unless that's all that's left.)
1768 const size_t min_expand_bytes = 1*M;
1769 size_t reserved_bytes = _g1->max_capacity();
1770 size_t committed_bytes = _g1->capacity();
1771 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1772 size_t expand_bytes;
1773 size_t expand_bytes_via_pct =
1774 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1775 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1776 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1777 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1778
1779 ergo_verbose5(ErgoHeapSizing,
1780 "attempt heap expansion",
1781 ergo_format_reason("recent GC overhead higher than "
1782 "threshold after GC")
1783 ergo_format_perc("recent GC overhead")
1784 ergo_format_perc("threshold")
1785 ergo_format_byte("uncommitted")
1786 ergo_format_byte_perc("calculated expansion amount"),
1787 recent_gc_overhead, threshold,
1788 uncommitted_bytes,
1789 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1790
1791 return expand_bytes;
1792 } else {
1793 return 0;
1794 }
1795 }
1796
1797 class CountCSClosure: public HeapRegionClosure {
1798 G1CollectorPolicy* _g1_policy;
1799 public:
1800 CountCSClosure(G1CollectorPolicy* g1_policy) :
1801 _g1_policy(g1_policy) {}
1802 bool doHeapRegion(HeapRegion* r) {
1803 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
1804 return false;
1805 }
1806 };
1807
1808 void G1CollectorPolicy::count_CS_bytes_used() {
1809 CountCSClosure cs_closure(this);
1810 _g1->collection_set_iterate(&cs_closure);
1811 }
1812
1813 void G1CollectorPolicy::print_summary(int level,
1814 const char* str,
1815 NumberSeq* seq) const {
1816 double sum = seq->sum();
1817 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
1818 str, sum / 1000.0, seq->avg());
1819 }
1820
1821 void G1CollectorPolicy::print_summary_sd(int level,
1822 const char* str,
1823 NumberSeq* seq) const {
1824 print_summary(level, str, seq);
1825 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
1826 seq->num(), seq->sd(), seq->maximum());
1827 }
1828
1829 void G1CollectorPolicy::check_other_times(int level,
1830 NumberSeq* other_times_ms,
1831 NumberSeq* calc_other_times_ms) const {
1832 bool should_print = false;
1833 LineBuffer buf(level + 2);
1834
1835 double max_sum = MAX2(fabs(other_times_ms->sum()),
1836 fabs(calc_other_times_ms->sum()));
1837 double min_sum = MIN2(fabs(other_times_ms->sum()),
1838 fabs(calc_other_times_ms->sum()));
1839 double sum_ratio = max_sum / min_sum;
1840 if (sum_ratio > 1.1) {
1841 should_print = true;
1842 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
1843 }
1844
1845 double max_avg = MAX2(fabs(other_times_ms->avg()),
1846 fabs(calc_other_times_ms->avg()));
1847 double min_avg = MIN2(fabs(other_times_ms->avg()),
1848 fabs(calc_other_times_ms->avg()));
1849 double avg_ratio = max_avg / min_avg;
1850 if (avg_ratio > 1.1) {
1851 should_print = true;
1852 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
1853 }
1854
1855 if (other_times_ms->sum() < -0.01) {
1856 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
1857 }
1858
1859 if (other_times_ms->avg() < -0.01) {
1860 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
1861 }
1862
1863 if (calc_other_times_ms->sum() < -0.01) {
1864 should_print = true;
1865 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
1866 }
1867
1868 if (calc_other_times_ms->avg() < -0.01) {
1869 should_print = true;
1870 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
1871 }
1872
1873 if (should_print)
1874 print_summary(level, "Other(Calc)", calc_other_times_ms);
1875 }
1876
1877 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
1878 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1879 MainBodySummary* body_summary = summary->main_body_summary();
1880 if (summary->get_total_seq()->num() > 0) {
1881 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
1882 if (body_summary != NULL) {
1883 print_summary(1, "Root Region Scan Wait", body_summary->get_root_region_scan_wait_seq());
1884 if (parallel) {
1885 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
1886 print_summary(2, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1887 print_summary(2, "SATB Filtering", body_summary->get_satb_filtering_seq());
1888 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
1889 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
1890 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
1891 print_summary(2, "Termination", body_summary->get_termination_seq());
1892 print_summary(2, "Parallel Other", body_summary->get_parallel_other_seq());
1893 {
1894 NumberSeq* other_parts[] = {
1895 body_summary->get_ext_root_scan_seq(),
1896 body_summary->get_satb_filtering_seq(),
1897 body_summary->get_update_rs_seq(),
1898 body_summary->get_scan_rs_seq(),
1899 body_summary->get_obj_copy_seq(),
1900 body_summary->get_termination_seq()
1901 };
1902 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
1903 6, other_parts);
1904 check_other_times(2, body_summary->get_parallel_other_seq(),
1905 &calc_other_times_ms);
1906 }
1907 } else {
1908 print_summary(1, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1909 print_summary(1, "SATB Filtering", body_summary->get_satb_filtering_seq());
1910 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
1911 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
1912 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
1913 }
1914 }
1915 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
1916 print_summary(1, "Other", summary->get_other_seq());
1917 {
1918 if (body_summary != NULL) {
1919 NumberSeq calc_other_times_ms;
1920 if (parallel) {
1921 // parallel
1922 NumberSeq* other_parts[] = {
1923 body_summary->get_root_region_scan_wait_seq(),
1924 body_summary->get_parallel_seq(),
1925 body_summary->get_clear_ct_seq()
1926 };
1927 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
1928 3, other_parts);
1929 } else {
1930 // serial
1931 NumberSeq* other_parts[] = {
1932 body_summary->get_root_region_scan_wait_seq(),
1933 body_summary->get_update_rs_seq(),
1934 body_summary->get_ext_root_scan_seq(),
1935 body_summary->get_satb_filtering_seq(),
1936 body_summary->get_scan_rs_seq(),
1937 body_summary->get_obj_copy_seq()
1938 };
1939 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
1940 6, other_parts);
1941 }
1942 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
1943 }
1944 }
1945 } else {
1946 LineBuffer(1).append_and_print_cr("none");
1947 }
1948 LineBuffer(0).append_and_print_cr("");
1949 }
1950
1951 void G1CollectorPolicy::print_tracing_info() const {
1952 if (TraceGen0Time) {
1953 gclog_or_tty->print_cr("ALL PAUSES");
1954 print_summary_sd(0, "Total", _all_pause_times_ms);
1955 gclog_or_tty->print_cr("");
1956 gclog_or_tty->print_cr("");
1957 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
1958 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
1959 gclog_or_tty->print_cr("");
1960
1961 gclog_or_tty->print_cr("EVACUATION PAUSES");
1962 print_summary(_summary);
1963
1964 gclog_or_tty->print_cr("MISC");
1965 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
1966 print_summary_sd(0, "Yields", _all_yield_times_ms);
1967 for (int i = 0; i < _aux_num; ++i) {
1968 if (_all_aux_times_ms[i].num() > 0) {
1969 char buffer[96];
1970 sprintf(buffer, "Aux%d", i);
1971 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
1972 }
1973 }
1974 }
1975 if (TraceGen1Time) {
1976 if (_all_full_gc_times_ms->num() > 0) {
1977 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
1978 _all_full_gc_times_ms->num(),
1979 _all_full_gc_times_ms->sum() / 1000.0);
1980 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
1981 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
1982 _all_full_gc_times_ms->sd(),
1983 _all_full_gc_times_ms->maximum());
1984 }
1985 }
1986 }
1987
1988 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1989 #ifndef PRODUCT
1990 _short_lived_surv_rate_group->print_surv_rate_summary();
1991 // add this call for any other surv rate groups
1992 #endif // PRODUCT
1993 }
1994
1995 #ifndef PRODUCT
1996 // for debugging, bit of a hack...
1997 static char*
1998 region_num_to_mbs(int length) {
1999 static char buffer[64];
2000 double bytes = (double) (length * HeapRegion::GrainBytes);
2001 double mbs = bytes / (double) (1024 * 1024);
2002 sprintf(buffer, "%7.2lfMB", mbs);
2003 return buffer;
2004 }
2005 #endif // PRODUCT
2006
2007 uint G1CollectorPolicy::max_regions(int purpose) {
2008 switch (purpose) {
2009 case GCAllocForSurvived:
2010 return _max_survivor_regions;
2011 case GCAllocForTenured:
2012 return REGIONS_UNLIMITED;
2013 default:
2014 ShouldNotReachHere();
2015 return REGIONS_UNLIMITED;
2016 };
2017 }
2018
2019 void G1CollectorPolicy::update_max_gc_locker_expansion() {
2020 uint expansion_region_num = 0;
2021 if (GCLockerEdenExpansionPercent > 0) {
2022 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2023 double expansion_region_num_d = perc * (double) _young_list_target_length;
2024 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2025 // less than 1.0) we'll get 1.
2026 expansion_region_num = (uint) ceil(expansion_region_num_d);
2027 } else {
2028 assert(expansion_region_num == 0, "sanity");
2029 }
2030 _young_list_max_length = _young_list_target_length + expansion_region_num;
2031 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2032 }
2033
2034 // Calculates survivor space parameters.
2035 void G1CollectorPolicy::update_survivors_policy() {
2036 double max_survivor_regions_d =
2037 (double) _young_list_target_length / (double) SurvivorRatio;
2038 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
2039 // smaller than 1.0) we'll get 1.
2040 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
2041
2042 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2043 HeapRegion::GrainWords * _max_survivor_regions);
2044 }
2045
2046 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
2047 GCCause::Cause gc_cause) {
2048 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2049 if (!during_cycle) {
2050 ergo_verbose1(ErgoConcCycles,
2051 "request concurrent cycle initiation",
2052 ergo_format_reason("requested by GC cause")
2053 ergo_format_str("GC cause"),
2054 GCCause::to_string(gc_cause));
2055 set_initiate_conc_mark_if_possible();
2056 return true;
2057 } else {
2058 ergo_verbose1(ErgoConcCycles,
2059 "do not request concurrent cycle initiation",
2060 ergo_format_reason("concurrent cycle already in progress")
2061 ergo_format_str("GC cause"),
2062 GCCause::to_string(gc_cause));
2063 return false;
2064 }
2065 }
2066
2067 void
2068 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2069 // We are about to decide on whether this pause will be an
2070 // initial-mark pause.
2071
2072 // First, during_initial_mark_pause() should not be already set. We
2073 // will set it here if we have to. However, it should be cleared by
2074 // the end of the pause (it's only set for the duration of an
2075 // initial-mark pause).
2076 assert(!during_initial_mark_pause(), "pre-condition");
2077
2078 if (initiate_conc_mark_if_possible()) {
2079 // We had noticed on a previous pause that the heap occupancy has
2080 // gone over the initiating threshold and we should start a
2081 // concurrent marking cycle. So we might initiate one.
2082
2083 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2084 if (!during_cycle) {
2085 // The concurrent marking thread is not "during a cycle", i.e.,
2086 // it has completed the last one. So we can go ahead and
2087 // initiate a new cycle.
2088
2089 set_during_initial_mark_pause();
2090 // We do not allow mixed GCs during marking.
2091 if (!gcs_are_young()) {
2092 set_gcs_are_young(true);
2093 ergo_verbose0(ErgoMixedGCs,
2094 "end mixed GCs",
2095 ergo_format_reason("concurrent cycle is about to start"));
2096 }
2097
2098 // And we can now clear initiate_conc_mark_if_possible() as
2099 // we've already acted on it.
2100 clear_initiate_conc_mark_if_possible();
2101
2102 ergo_verbose0(ErgoConcCycles,
2103 "initiate concurrent cycle",
2104 ergo_format_reason("concurrent cycle initiation requested"));
2105 } else {
2106 // The concurrent marking thread is still finishing up the
2107 // previous cycle. If we start one right now the two cycles
2108 // overlap. In particular, the concurrent marking thread might
2109 // be in the process of clearing the next marking bitmap (which
2110 // we will use for the next cycle if we start one). Starting a
2111 // cycle now will be bad given that parts of the marking
2112 // information might get cleared by the marking thread. And we
2113 // cannot wait for the marking thread to finish the cycle as it
2114 // periodically yields while clearing the next marking bitmap
2115 // and, if it's in a yield point, it's waiting for us to
2116 // finish. So, at this point we will not start a cycle and we'll
2117 // let the concurrent marking thread complete the last one.
2118 ergo_verbose0(ErgoConcCycles,
2119 "do not initiate concurrent cycle",
2120 ergo_format_reason("concurrent cycle already in progress"));
2121 }
2122 }
2123 }
2124
2125 class KnownGarbageClosure: public HeapRegionClosure {
2126 G1CollectedHeap* _g1h;
2127 CollectionSetChooser* _hrSorted;
2128
2129 public:
2130 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2131 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
2132
2133 bool doHeapRegion(HeapRegion* r) {
2134 // We only include humongous regions in collection
2135 // sets when concurrent mark shows that their contained object is
2136 // unreachable.
2137
2138 // Do we have any marking information for this region?
2139 if (r->is_marked()) {
2140 // We will skip any region that's currently used as an old GC
2141 // alloc region (we should not consider those for collection
2142 // before we fill them up).
2143 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
2144 _hrSorted->add_region(r);
2145 }
2146 }
2147 return false;
2148 }
2149 };
2150
2151 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2152 G1CollectedHeap* _g1h;
2153 CollectionSetChooser* _hrSorted;
2154 uint _marked_regions_added;
2155 size_t _reclaimable_bytes_added;
2156 uint _chunk_size;
2157 uint _cur_chunk_idx;
2158 uint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2159
2160 void get_new_chunk() {
2161 _cur_chunk_idx = _hrSorted->claim_array_chunk(_chunk_size);
2162 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2163 }
2164 void add_region(HeapRegion* r) {
2165 if (_cur_chunk_idx == _cur_chunk_end) {
2166 get_new_chunk();
2167 }
2168 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2169 _hrSorted->set_region(_cur_chunk_idx, r);
2170 _marked_regions_added++;
2171 _reclaimable_bytes_added += r->reclaimable_bytes();
2172 _cur_chunk_idx++;
2173 }
2174
2175 public:
2176 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2177 uint chunk_size) :
2178 _g1h(G1CollectedHeap::heap()),
2179 _hrSorted(hrSorted), _chunk_size(chunk_size),
2180 _marked_regions_added(0), _reclaimable_bytes_added(0),
2181 _cur_chunk_idx(0), _cur_chunk_end(0) { }
2182
2183 bool doHeapRegion(HeapRegion* r) {
2184 // Do we have any marking information for this region?
2185 if (r->is_marked()) {
2186 // We will skip any region that's currently used as an old GC
2187 // alloc region (we should not consider those for collection
2188 // before we fill them up).
2189 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
2190 add_region(r);
2191 }
2192 }
2193 return false;
2194 }
2195 uint marked_regions_added() { return _marked_regions_added; }
2196 size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
2197 };
2198
2199 class ParKnownGarbageTask: public AbstractGangTask {
2200 CollectionSetChooser* _hrSorted;
2201 uint _chunk_size;
2202 G1CollectedHeap* _g1;
2203 public:
2204 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
2205 AbstractGangTask("ParKnownGarbageTask"),
2206 _hrSorted(hrSorted), _chunk_size(chunk_size),
2207 _g1(G1CollectedHeap::heap()) { }
2208
2209 void work(uint worker_id) {
2210 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
2211
2212 // Back to zero for the claim value.
2213 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
2214 _g1->workers()->active_workers(),
2215 HeapRegion::InitialClaimValue);
2216 uint regions_added = parKnownGarbageCl.marked_regions_added();
2217 size_t reclaimable_bytes_added =
2218 parKnownGarbageCl.reclaimable_bytes_added();
2219 _hrSorted->update_totals(regions_added, reclaimable_bytes_added);
2220 }
2221 };
2222
2223 void
2224 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
2225 _collectionSetChooser->clear();
2226
2227 uint region_num = _g1->n_regions();
2228 if (G1CollectedHeap::use_parallel_gc_threads()) {
2229 const uint OverpartitionFactor = 4;
2230 uint WorkUnit;
2231 // The use of MinChunkSize = 8 in the original code
2232 // causes some assertion failures when the total number of
2233 // region is less than 8. The code here tries to fix that.
2234 // Should the original code also be fixed?
2235 if (no_of_gc_threads > 0) {
2236 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
2237 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
2238 MinWorkUnit);
2239 } else {
2240 assert(no_of_gc_threads > 0,
2241 "The active gc workers should be greater than 0");
2242 // In a product build do something reasonable to avoid a crash.
2243 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
2244 WorkUnit =
2245 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
2246 MinWorkUnit);
2247 }
2248 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
2249 WorkUnit);
2250 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2251 (int) WorkUnit);
2252 _g1->workers()->run_task(&parKnownGarbageTask);
2253
2254 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2255 "sanity check");
2256 } else {
2257 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2258 _g1->heap_region_iterate(&knownGarbagecl);
2259 }
2260
2261 _collectionSetChooser->sort_regions();
2262
2263 double end_sec = os::elapsedTime();
2264 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
2265 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
2266 _cur_mark_stop_world_time_ms += elapsed_time_ms;
2267 _prev_collection_pause_end_ms += elapsed_time_ms;
2268 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
2269 }
2270
2271 // Add the heap region at the head of the non-incremental collection set
2272 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
2273 assert(_inc_cset_build_state == Active, "Precondition");
2274 assert(!hr->is_young(), "non-incremental add of young region");
2275
2276 assert(!hr->in_collection_set(), "should not already be in the CSet");
2277 hr->set_in_collection_set(true);
2278 hr->set_next_in_collection_set(_collection_set);
2279 _collection_set = hr;
2280 _collection_set_bytes_used_before += hr->used();
2281 _g1->register_region_with_in_cset_fast_test(hr);
2282 size_t rs_length = hr->rem_set()->occupied();
2283 _recorded_rs_lengths += rs_length;
2284 _old_cset_region_length += 1;
2285 }
2286
2287 // Initialize the per-collection-set information
2288 void G1CollectorPolicy::start_incremental_cset_building() {
2289 assert(_inc_cset_build_state == Inactive, "Precondition");
2290
2291 _inc_cset_head = NULL;
2292 _inc_cset_tail = NULL;
2293 _inc_cset_bytes_used_before = 0;
2294
2295 _inc_cset_max_finger = 0;
2296 _inc_cset_recorded_rs_lengths = 0;
2297 _inc_cset_recorded_rs_lengths_diffs = 0;
2298 _inc_cset_predicted_elapsed_time_ms = 0.0;
2299 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2300 _inc_cset_build_state = Active;
2301 }
2302
2303 void G1CollectorPolicy::finalize_incremental_cset_building() {
2304 assert(_inc_cset_build_state == Active, "Precondition");
2305 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2306
2307 // The two "main" fields, _inc_cset_recorded_rs_lengths and
2308 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
2309 // that adds a new region to the CSet. Further updates by the
2310 // concurrent refinement thread that samples the young RSet lengths
2311 // are accumulated in the *_diffs fields. Here we add the diffs to
2312 // the "main" fields.
2313
2314 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
2315 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
2316 } else {
2317 // This is defensive. The diff should in theory be always positive
2318 // as RSets can only grow between GCs. However, given that we
2319 // sample their size concurrently with other threads updating them
2320 // it's possible that we might get the wrong size back, which
2321 // could make the calculations somewhat inaccurate.
2322 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
2323 if (_inc_cset_recorded_rs_lengths >= diffs) {
2324 _inc_cset_recorded_rs_lengths -= diffs;
2325 } else {
2326 _inc_cset_recorded_rs_lengths = 0;
2327 }
2328 }
2329 _inc_cset_predicted_elapsed_time_ms +=
2330 _inc_cset_predicted_elapsed_time_ms_diffs;
2331
2332 _inc_cset_recorded_rs_lengths_diffs = 0;
2333 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2334 }
2335
2336 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2337 // This routine is used when:
2338 // * adding survivor regions to the incremental cset at the end of an
2339 // evacuation pause,
2340 // * adding the current allocation region to the incremental cset
2341 // when it is retired, and
2342 // * updating existing policy information for a region in the
2343 // incremental cset via young list RSet sampling.
2344 // Therefore this routine may be called at a safepoint by the
2345 // VM thread, or in-between safepoints by mutator threads (when
2346 // retiring the current allocation region) or a concurrent
2347 // refine thread (RSet sampling).
2348
2349 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2350 size_t used_bytes = hr->used();
2351 _inc_cset_recorded_rs_lengths += rs_length;
2352 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2353 _inc_cset_bytes_used_before += used_bytes;
2354
2355 // Cache the values we have added to the aggregated informtion
2356 // in the heap region in case we have to remove this region from
2357 // the incremental collection set, or it is updated by the
2358 // rset sampling code
2359 hr->set_recorded_rs_length(rs_length);
2360 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2361 }
2362
2363 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
2364 size_t new_rs_length) {
2365 // Update the CSet information that is dependent on the new RS length
2366 assert(hr->is_young(), "Precondition");
2367 assert(!SafepointSynchronize::is_at_safepoint(),
2368 "should not be at a safepoint");
2369
2370 // We could have updated _inc_cset_recorded_rs_lengths and
2371 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
2372 // that atomically, as this code is executed by a concurrent
2373 // refinement thread, potentially concurrently with a mutator thread
2374 // allocating a new region and also updating the same fields. To
2375 // avoid the atomic operations we accumulate these updates on two
2376 // separate fields (*_diffs) and we'll just add them to the "main"
2377 // fields at the start of a GC.
2378
2379 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
2380 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
2381 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
2382
2383 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2384 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2385 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
2386 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
2387
2388 hr->set_recorded_rs_length(new_rs_length);
2389 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
2390 }
2391
2392 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2393 assert(hr->is_young(), "invariant");
2394 assert(hr->young_index_in_cset() > -1, "should have already been set");
2395 assert(_inc_cset_build_state == Active, "Precondition");
2396
2397 // We need to clear and set the cached recorded/cached collection set
2398 // information in the heap region here (before the region gets added
2399 // to the collection set). An individual heap region's cached values
2400 // are calculated, aggregated with the policy collection set info,
2401 // and cached in the heap region here (initially) and (subsequently)
2402 // by the Young List sampling code.
2403
2404 size_t rs_length = hr->rem_set()->occupied();
2405 add_to_incremental_cset_info(hr, rs_length);
2406
2407 HeapWord* hr_end = hr->end();
2408 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2409
2410 assert(!hr->in_collection_set(), "invariant");
2411 hr->set_in_collection_set(true);
2412 assert( hr->next_in_collection_set() == NULL, "invariant");
2413
2414 _g1->register_region_with_in_cset_fast_test(hr);
2415 }
2416
2417 // Add the region at the RHS of the incremental cset
2418 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2419 // We should only ever be appending survivors at the end of a pause
2420 assert( hr->is_survivor(), "Logic");
2421
2422 // Do the 'common' stuff
2423 add_region_to_incremental_cset_common(hr);
2424
2425 // Now add the region at the right hand side
2426 if (_inc_cset_tail == NULL) {
2427 assert(_inc_cset_head == NULL, "invariant");
2428 _inc_cset_head = hr;
2429 } else {
2430 _inc_cset_tail->set_next_in_collection_set(hr);
2431 }
2432 _inc_cset_tail = hr;
2433 }
2434
2435 // Add the region to the LHS of the incremental cset
2436 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2437 // Survivors should be added to the RHS at the end of a pause
2438 assert(!hr->is_survivor(), "Logic");
2439
2440 // Do the 'common' stuff
2441 add_region_to_incremental_cset_common(hr);
2442
2443 // Add the region at the left hand side
2444 hr->set_next_in_collection_set(_inc_cset_head);
2445 if (_inc_cset_head == NULL) {
2446 assert(_inc_cset_tail == NULL, "Invariant");
2447 _inc_cset_tail = hr;
2448 }
2449 _inc_cset_head = hr;
2450 }
2451
2452 #ifndef PRODUCT
2453 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2454 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2455
2456 st->print_cr("\nCollection_set:");
2457 HeapRegion* csr = list_head;
2458 while (csr != NULL) {
2459 HeapRegion* next = csr->next_in_collection_set();
2460 assert(csr->in_collection_set(), "bad CS");
2461 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
2462 HR_FORMAT_PARAMS(csr),
2463 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
2464 csr->age_in_surv_rate_group_cond());
2465 csr = next;
2466 }
2467 }
2468 #endif // !PRODUCT
2469
2470 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2471 const char* false_action_str) {
2472 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2473 if (cset_chooser->is_empty()) {
2474 ergo_verbose0(ErgoMixedGCs,
2475 false_action_str,
2476 ergo_format_reason("candidate old regions not available"));
2477 return false;
2478 }
2479 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2480 size_t capacity_bytes = _g1->capacity();
2481 double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2482 double threshold = (double) G1HeapWastePercent;
2483 if (perc < threshold) {
2484 ergo_verbose4(ErgoMixedGCs,
2485 false_action_str,
2486 ergo_format_reason("reclaimable percentage lower than threshold")
2487 ergo_format_region("candidate old regions")
2488 ergo_format_byte_perc("reclaimable")
2489 ergo_format_perc("threshold"),
2490 cset_chooser->remaining_regions(),
2491 reclaimable_bytes, perc, threshold);
2492 return false;
2493 }
2494
2495 ergo_verbose4(ErgoMixedGCs,
2496 true_action_str,
2497 ergo_format_reason("candidate old regions available")
2498 ergo_format_region("candidate old regions")
2499 ergo_format_byte_perc("reclaimable")
2500 ergo_format_perc("threshold"),
2501 cset_chooser->remaining_regions(),
2502 reclaimable_bytes, perc, threshold);
2503 return true;
2504 }
2505
2506 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
2507 // Set this here - in case we're not doing young collections.
2508 double non_young_start_time_sec = os::elapsedTime();
2509
2510 YoungList* young_list = _g1->young_list();
2511 finalize_incremental_cset_building();
2512
2513 guarantee(target_pause_time_ms > 0.0,
2514 err_msg("target_pause_time_ms = %1.6lf should be positive",
2515 target_pause_time_ms));
2516 guarantee(_collection_set == NULL, "Precondition");
2517
2518 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2519 double predicted_pause_time_ms = base_time_ms;
2520 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2521
2522 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2523 "start choosing CSet",
2524 ergo_format_ms("predicted base time")
2525 ergo_format_ms("remaining time")
2526 ergo_format_ms("target pause time"),
2527 base_time_ms, time_remaining_ms, target_pause_time_ms);
2528
2529 HeapRegion* hr;
2530 double young_start_time_sec = os::elapsedTime();
2531
2532 _collection_set_bytes_used_before = 0;
2533 _last_gc_was_young = gcs_are_young() ? true : false;
2534
2535 if (_last_gc_was_young) {
2536 ++_young_pause_num;
2537 } else {
2538 ++_mixed_pause_num;
2539 }
2540
2541 // The young list is laid with the survivor regions from the previous
2542 // pause are appended to the RHS of the young list, i.e.
2543 // [Newly Young Regions ++ Survivors from last pause].
2544
2545 uint survivor_region_length = young_list->survivor_length();
2546 uint eden_region_length = young_list->length() - survivor_region_length;
2547 init_cset_region_lengths(eden_region_length, survivor_region_length);
2548 hr = young_list->first_survivor_region();
2549 while (hr != NULL) {
2550 assert(hr->is_survivor(), "badly formed young list");
2551 hr->set_young();
2552 hr = hr->get_next_young_region();
2553 }
2554
2555 // Clear the fields that point to the survivor list - they are all young now.
2556 young_list->clear_survivors();
2557
2558 _collection_set = _inc_cset_head;
2559 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2560 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2561 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2562
2563 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2564 "add young regions to CSet",
2565 ergo_format_region("eden")
2566 ergo_format_region("survivors")
2567 ergo_format_ms("predicted young region time"),
2568 eden_region_length, survivor_region_length,
2569 _inc_cset_predicted_elapsed_time_ms);
2570
2571 // The number of recorded young regions is the incremental
2572 // collection set's current size
2573 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2574
2575 double young_end_time_sec = os::elapsedTime();
2576 _recorded_young_cset_choice_time_ms =
2577 (young_end_time_sec - young_start_time_sec) * 1000.0;
2578
2579 // We are doing young collections so reset this.
2580 non_young_start_time_sec = young_end_time_sec;
2581
2582 if (!gcs_are_young()) {
2583 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2584 cset_chooser->verify();
2585 const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
2586 const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
2587
2588 uint expensive_region_num = 0;
2589 bool check_time_remaining = adaptive_young_list_length();
2590 HeapRegion* hr = cset_chooser->peek();
2591 while (hr != NULL) {
2592 if (old_cset_region_length() >= max_old_cset_length) {
2593 // Added maximum number of old regions to the CSet.
2594 ergo_verbose2(ErgoCSetConstruction,
2595 "finish adding old regions to CSet",
2596 ergo_format_reason("old CSet region num reached max")
2597 ergo_format_region("old")
2598 ergo_format_region("max"),
2599 old_cset_region_length(), max_old_cset_length);
2600 break;
2601 }
2602
2603 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2604 if (check_time_remaining) {
2605 if (predicted_time_ms > time_remaining_ms) {
2606 // Too expensive for the current CSet.
2607
2608 if (old_cset_region_length() >= min_old_cset_length) {
2609 // We have added the minimum number of old regions to the CSet,
2610 // we are done with this CSet.
2611 ergo_verbose4(ErgoCSetConstruction,
2612 "finish adding old regions to CSet",
2613 ergo_format_reason("predicted time is too high")
2614 ergo_format_ms("predicted time")
2615 ergo_format_ms("remaining time")
2616 ergo_format_region("old")
2617 ergo_format_region("min"),
2618 predicted_time_ms, time_remaining_ms,
2619 old_cset_region_length(), min_old_cset_length);
2620 break;
2621 }
2622
2623 // We'll add it anyway given that we haven't reached the
2624 // minimum number of old regions.
2625 expensive_region_num += 1;
2626 }
2627 } else {
2628 if (old_cset_region_length() >= min_old_cset_length) {
2629 // In the non-auto-tuning case, we'll finish adding regions
2630 // to the CSet if we reach the minimum.
2631 ergo_verbose2(ErgoCSetConstruction,
2632 "finish adding old regions to CSet",
2633 ergo_format_reason("old CSet region num reached min")
2634 ergo_format_region("old")
2635 ergo_format_region("min"),
2636 old_cset_region_length(), min_old_cset_length);
2637 break;
2638 }
2639 }
2640
2641 // We will add this region to the CSet.
2642 time_remaining_ms -= predicted_time_ms;
2643 predicted_pause_time_ms += predicted_time_ms;
2644 cset_chooser->remove_and_move_to_next(hr);
2645 _g1->old_set_remove(hr);
2646 add_old_region_to_cset(hr);
2647
2648 hr = cset_chooser->peek();
2649 }
2650 if (hr == NULL) {
2651 ergo_verbose0(ErgoCSetConstruction,
2652 "finish adding old regions to CSet",
2653 ergo_format_reason("candidate old regions not available"));
2654 }
2655
2656 if (expensive_region_num > 0) {
2657 // We print the information once here at the end, predicated on
2658 // whether we added any apparently expensive regions or not, to
2659 // avoid generating output per region.
2660 ergo_verbose4(ErgoCSetConstruction,
2661 "added expensive regions to CSet",
2662 ergo_format_reason("old CSet region num not reached min")
2663 ergo_format_region("old")
2664 ergo_format_region("expensive")
2665 ergo_format_region("min")
2666 ergo_format_ms("remaining time"),
2667 old_cset_region_length(),
2668 expensive_region_num,
2669 min_old_cset_length,
2670 time_remaining_ms);
2671 }
2672
2673 cset_chooser->verify();
2674 }
2675
2676 stop_incremental_cset_building();
2677
2678 count_CS_bytes_used();
2679
2680 ergo_verbose5(ErgoCSetConstruction,
2681 "finish choosing CSet",
2682 ergo_format_region("eden")
2683 ergo_format_region("survivors")
2684 ergo_format_region("old")
2685 ergo_format_ms("predicted pause time")
2686 ergo_format_ms("target pause time"),
2687 eden_region_length, survivor_region_length,
2688 old_cset_region_length(),
2689 predicted_pause_time_ms, target_pause_time_ms);
2690
2691 double non_young_end_time_sec = os::elapsedTime();
2692 _recorded_non_young_cset_choice_time_ms =
2693 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2694 }