1 /*
2 * Copyright (c) 2001, 2011, 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/heapRegionRemSet.hpp"
32 #include "gc_implementation/shared/gcPolicyCounters.hpp"
33 #include "runtime/arguments.hpp"
34 #include "runtime/java.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "utilities/debug.hpp"
37
38 #define PREDICTIONS_VERBOSE 0
39
40 // <NEW PREDICTION>
41
42 // Different defaults for different number of GC threads
43 // They were chosen by running GCOld and SPECjbb on debris with different
44 // numbers of GC threads and choosing them based on the results
45
46 // all the same
47 static double rs_length_diff_defaults[] = {
48 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
49 };
50
51 static double cost_per_card_ms_defaults[] = {
52 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
53 };
54
55 // all the same
56 static double fully_young_cards_per_entry_ratio_defaults[] = {
57 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
58 };
59
60 static double cost_per_entry_ms_defaults[] = {
61 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
62 };
63
64 static double cost_per_byte_ms_defaults[] = {
65 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
66 };
67
68 // these should be pretty consistent
69 static double constant_other_time_ms_defaults[] = {
70 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
71 };
72
73
74 static double young_other_cost_per_region_ms_defaults[] = {
75 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
76 };
77
78 static double non_young_other_cost_per_region_ms_defaults[] = {
79 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
80 };
81
82 // </NEW PREDICTION>
83
84 // Help class for avoiding interleaved logging
85 class LineBuffer: public StackObj {
86
87 private:
88 static const int BUFFER_LEN = 1024;
89 static const int INDENT_CHARS = 3;
90 char _buffer[BUFFER_LEN];
91 int _indent_level;
92 int _cur;
93
94 void vappend(const char* format, va_list ap) {
95 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
96 if (res != -1) {
97 _cur += res;
98 } else {
99 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
100 _buffer[BUFFER_LEN -1] = 0;
101 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
102 }
103 }
104
105 public:
106 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
107 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
108 _buffer[_cur] = ' ';
109 }
110 }
111
112 #ifndef PRODUCT
113 ~LineBuffer() {
114 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
115 }
116 #endif
117
118 void append(const char* format, ...) {
119 va_list ap;
120 va_start(ap, format);
121 vappend(format, ap);
122 va_end(ap);
123 }
124
125 void append_and_print_cr(const char* format, ...) {
126 va_list ap;
127 va_start(ap, format);
128 vappend(format, ap);
129 va_end(ap);
130 gclog_or_tty->print_cr("%s", _buffer);
131 _cur = _indent_level * INDENT_CHARS;
132 }
133 };
134
135 G1CollectorPolicy::G1CollectorPolicy() :
136 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
137 ? ParallelGCThreads : 1),
138
139 _n_pauses(0),
140 _recent_rs_scan_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
141 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
142 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
143 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
144 _all_pause_times_ms(new NumberSeq()),
145 _stop_world_start(0.0),
146 _all_stop_world_times_ms(new NumberSeq()),
147 _all_yield_times_ms(new NumberSeq()),
148
149 _all_mod_union_times_ms(new NumberSeq()),
150
151 _summary(new Summary()),
152
153 #ifndef PRODUCT
154 _cur_clear_ct_time_ms(0.0),
155 _min_clear_cc_time_ms(-1.0),
156 _max_clear_cc_time_ms(-1.0),
157 _cur_clear_cc_time_ms(0.0),
158 _cum_clear_cc_time_ms(0.0),
159 _num_cc_clears(0L),
160 #endif
161
162 _region_num_young(0),
163 _region_num_tenured(0),
164 _prev_region_num_young(0),
165 _prev_region_num_tenured(0),
166
167 _aux_num(10),
168 _all_aux_times_ms(new NumberSeq[_aux_num]),
169 _cur_aux_start_times_ms(new double[_aux_num]),
170 _cur_aux_times_ms(new double[_aux_num]),
171 _cur_aux_times_set(new bool[_aux_num]),
172
173 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
174 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
175 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
176
177 // <NEW PREDICTION>
178
179 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
180 _prev_collection_pause_end_ms(0.0),
181 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
182 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
183 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
184 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
185 _partially_young_cards_per_entry_ratio_seq(
186 new TruncatedSeq(TruncatedSeqLength)),
187 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
188 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
189 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
190 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
191 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
192 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
193 _non_young_other_cost_per_region_ms_seq(
194 new TruncatedSeq(TruncatedSeqLength)),
195
196 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
197 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
198 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
199
200 _pause_time_target_ms((double) MaxGCPauseMillis),
201
202 // </NEW PREDICTION>
203
204 _full_young_gcs(true),
205 _full_young_pause_num(0),
206 _partial_young_pause_num(0),
207
208 _during_marking(false),
209 _in_marking_window(false),
210 _in_marking_window_im(false),
211
212 _known_garbage_ratio(0.0),
213 _known_garbage_bytes(0),
214
215 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
216
217 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
218
219 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
220 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
221
222 _recent_avg_pause_time_ratio(0.0),
223 _num_markings(0),
224 _n_marks(0),
225 _n_pauses_at_mark_end(0),
226
227 _all_full_gc_times_ms(new NumberSeq()),
228
229 // G1PausesBtwnConcMark defaults to -1
230 // so the hack is to do the cast QQQ FIXME
231 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
232 _n_marks_since_last_pause(0),
233 _initiate_conc_mark_if_possible(false),
234 _during_initial_mark_pause(false),
235 _should_revert_to_full_young_gcs(false),
236 _last_full_young_gc(false),
237
238 _eden_bytes_before_gc(0),
239 _survivor_bytes_before_gc(0),
240 _capacity_before_gc(0),
241
242 _prev_collection_pause_used_at_end_bytes(0),
243
244 _collection_set(NULL),
245 _collection_set_size(0),
246 _collection_set_bytes_used_before(0),
247
248 // Incremental CSet attributes
249 _inc_cset_build_state(Inactive),
250 _inc_cset_head(NULL),
251 _inc_cset_tail(NULL),
252 _inc_cset_size(0),
253 _inc_cset_young_index(0),
254 _inc_cset_bytes_used_before(0),
255 _inc_cset_max_finger(NULL),
256 _inc_cset_recorded_young_bytes(0),
257 _inc_cset_recorded_rs_lengths(0),
258 _inc_cset_predicted_elapsed_time_ms(0.0),
259 _inc_cset_predicted_bytes_to_copy(0),
260
261 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
262 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
263 #endif // _MSC_VER
264
265 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
266 G1YoungSurvRateNumRegionsSummary)),
267 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
268 G1YoungSurvRateNumRegionsSummary)),
269 // add here any more surv rate groups
270 _recorded_survivor_regions(0),
271 _recorded_survivor_head(NULL),
272 _recorded_survivor_tail(NULL),
273 _survivors_age_table(true),
274
275 _gc_overhead_perc(0.0)
276
277 {
278 // Set up the region size and associated fields. Given that the
279 // policy is created before the heap, we have to set this up here,
280 // so it's done as soon as possible.
281 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
282 HeapRegionRemSet::setup_remset_size();
283
284 // Verify PLAB sizes
285 const uint region_size = HeapRegion::GrainWords;
286 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
287 char buffer[128];
288 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
289 OldPLABSize > region_size ? "Old" : "Young", region_size);
290 vm_exit_during_initialization(buffer);
291 }
292
293 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
294 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
295
296 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
297 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
298 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
299
300 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
301 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
302
303 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
304
305 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
306
307 _par_last_termination_times_ms = new double[_parallel_gc_threads];
308 _par_last_termination_attempts = new double[_parallel_gc_threads];
309 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
310 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
311
312 // start conservatively
313 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
314
315 // <NEW PREDICTION>
316
317 int index;
318 if (ParallelGCThreads == 0)
319 index = 0;
320 else if (ParallelGCThreads > 8)
321 index = 7;
322 else
323 index = ParallelGCThreads - 1;
324
325 _pending_card_diff_seq->add(0.0);
326 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
327 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
328 _fully_young_cards_per_entry_ratio_seq->add(
329 fully_young_cards_per_entry_ratio_defaults[index]);
330 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
331 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
332 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
333 _young_other_cost_per_region_ms_seq->add(
334 young_other_cost_per_region_ms_defaults[index]);
335 _non_young_other_cost_per_region_ms_seq->add(
336 non_young_other_cost_per_region_ms_defaults[index]);
337
338 // </NEW PREDICTION>
339
340 // Below, we might need to calculate the pause time target based on
341 // the pause interval. When we do so we are going to give G1 maximum
342 // flexibility and allow it to do pauses when it needs to. So, we'll
343 // arrange that the pause interval to be pause time target + 1 to
344 // ensure that a) the pause time target is maximized with respect to
345 // the pause interval and b) we maintain the invariant that pause
346 // time target < pause interval. If the user does not want this
347 // maximum flexibility, they will have to set the pause interval
348 // explicitly.
349
350 // First make sure that, if either parameter is set, its value is
351 // reasonable.
352 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
353 if (MaxGCPauseMillis < 1) {
354 vm_exit_during_initialization("MaxGCPauseMillis should be "
355 "greater than 0");
356 }
357 }
358 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
359 if (GCPauseIntervalMillis < 1) {
360 vm_exit_during_initialization("GCPauseIntervalMillis should be "
361 "greater than 0");
362 }
363 }
364
365 // Then, if the pause time target parameter was not set, set it to
366 // the default value.
367 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
368 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
369 // The default pause time target in G1 is 200ms
370 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
371 } else {
372 // We do not allow the pause interval to be set without the
373 // pause time target
374 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
375 "without setting MaxGCPauseMillis");
376 }
377 }
378
379 // Then, if the interval parameter was not set, set it according to
380 // the pause time target (this will also deal with the case when the
381 // pause time target is the default value).
382 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
383 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
384 }
385
386 // Finally, make sure that the two parameters are consistent.
387 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
388 char buffer[256];
389 jio_snprintf(buffer, 256,
390 "MaxGCPauseMillis (%u) should be less than "
391 "GCPauseIntervalMillis (%u)",
392 MaxGCPauseMillis, GCPauseIntervalMillis);
393 vm_exit_during_initialization(buffer);
394 }
395
396 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
397 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
398 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
399 _sigma = (double) G1ConfidencePercent / 100.0;
400
401 // start conservatively (around 50ms is about right)
402 _concurrent_mark_init_times_ms->add(0.05);
403 _concurrent_mark_remark_times_ms->add(0.05);
404 _concurrent_mark_cleanup_times_ms->add(0.20);
405 _tenuring_threshold = MaxTenuringThreshold;
406
407 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
408 // fixed, then _max_survivor_regions will be calculated at
409 // calculate_young_list_target_length during initialization
410 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
411
412 assert(GCTimeRatio > 0,
413 "we should have set it to a default value set_g1_gc_flags() "
414 "if a user set it to 0");
415 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
416
417 initialize_all();
418 }
419
420 // Increment "i", mod "len"
421 static void inc_mod(int& i, int len) {
422 i++; if (i == len) i = 0;
423 }
424
425 void G1CollectorPolicy::initialize_flags() {
426 set_min_alignment(HeapRegion::GrainBytes);
427 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
428 if (SurvivorRatio < 1) {
429 vm_exit_during_initialization("Invalid survivor ratio specified");
430 }
431 CollectorPolicy::initialize_flags();
432 }
433
434 // The easiest way to deal with the parsing of the NewSize /
435 // MaxNewSize / etc. parameteres is to re-use the code in the
436 // TwoGenerationCollectorPolicy class. This is similar to what
437 // ParallelScavenge does with its GenerationSizer class (see
438 // ParallelScavengeHeap::initialize()). We might change this in the
439 // future, but it's a good start.
440 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
441 size_t size_to_region_num(size_t byte_size) {
442 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
443 }
444
445 public:
446 G1YoungGenSizer() {
447 initialize_flags();
448 initialize_size_info();
449 }
450
451 size_t min_young_region_num() {
452 return size_to_region_num(_min_gen0_size);
453 }
454 size_t initial_young_region_num() {
455 return size_to_region_num(_initial_gen0_size);
456 }
457 size_t max_young_region_num() {
458 return size_to_region_num(_max_gen0_size);
459 }
460 };
461
462 void G1CollectorPolicy::init() {
463 // Set aside an initial future to_space.
464 _g1 = G1CollectedHeap::heap();
465
466 assert(Heap_lock->owned_by_self(), "Locking discipline.");
467
468 initialize_gc_policy_counters();
469
470 G1YoungGenSizer sizer;
471 size_t initial_region_num = sizer.initial_young_region_num();
472
473 if (UseAdaptiveSizePolicy) {
474 set_adaptive_young_list_length(true);
475 _young_list_fixed_length = 0;
476 } else {
477 set_adaptive_young_list_length(false);
478 _young_list_fixed_length = initial_region_num;
479 }
480 _free_regions_at_end_of_collection = _g1->free_regions();
481 calculate_young_list_min_length();
482 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
483 calculate_young_list_target_length();
484
485 // We may immediately start allocating regions and placing them on the
486 // collection set list. Initialize the per-collection set info
487 start_incremental_cset_building();
488 }
489
490 // Create the jstat counters for the policy.
491 void G1CollectorPolicy::initialize_gc_policy_counters()
492 {
493 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
494 }
495
496 void G1CollectorPolicy::calculate_young_list_min_length() {
497 _young_list_min_length = 0;
498
499 if (!adaptive_young_list_length())
500 return;
501
502 if (_alloc_rate_ms_seq->num() > 3) {
503 double now_sec = os::elapsedTime();
504 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
505 double alloc_rate_ms = predict_alloc_rate_ms();
506 size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
507 size_t current_region_num = _g1->young_list()->length();
508 _young_list_min_length = min_regions + current_region_num;
509 }
510 }
511
512 void G1CollectorPolicy::calculate_young_list_target_length() {
513 if (adaptive_young_list_length()) {
514 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
515 calculate_young_list_target_length(rs_lengths);
516 } else {
517 if (full_young_gcs())
518 _young_list_target_length = _young_list_fixed_length;
519 else
520 _young_list_target_length = _young_list_fixed_length / 2;
521 }
522
523 // Make sure we allow the application to allocate at least one
524 // region before we need to do a collection again.
525 size_t min_length = _g1->young_list()->length() + 1;
526 _young_list_target_length = MAX2(_young_list_target_length, min_length);
527 calculate_max_gc_locker_expansion();
528 calculate_survivors_policy();
529 }
530
531 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
532 guarantee( adaptive_young_list_length(), "pre-condition" );
533 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
534
535 double start_time_sec = os::elapsedTime();
536 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
537 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
538 size_t reserve_regions =
539 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
540
541 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
542 // we are in fully-young mode and there are free regions in the heap
543
544 double survivor_regions_evac_time =
545 predict_survivor_regions_evac_time();
546
547 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
548 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
549 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
550 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
551 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
552 + survivor_regions_evac_time;
553
554 // the result
555 size_t final_young_length = 0;
556
557 size_t init_free_regions =
558 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
559
560 // if we're still under the pause target...
561 if (base_time_ms <= target_pause_time_ms) {
562 // We make sure that the shortest young length that makes sense
563 // fits within the target pause time.
564 size_t min_young_length = 1;
565
566 if (predict_will_fit(min_young_length, base_time_ms,
567 init_free_regions, target_pause_time_ms)) {
568 // The shortest young length will fit within the target pause time;
569 // we'll now check whether the absolute maximum number of young
570 // regions will fit in the target pause time. If not, we'll do
571 // a binary search between min_young_length and max_young_length
572 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
573 size_t max_young_length = abs_max_young_length;
574
575 if (max_young_length > min_young_length) {
576 // Let's check if the initial max young length will fit within the
577 // target pause. If so then there is no need to search for a maximal
578 // young length - we'll return the initial maximum
579
580 if (predict_will_fit(max_young_length, base_time_ms,
581 init_free_regions, target_pause_time_ms)) {
582 // The maximum young length will satisfy the target pause time.
583 // We are done so set min young length to this maximum length.
584 // The code after the loop will then set final_young_length using
585 // the value cached in the minimum length.
586 min_young_length = max_young_length;
587 } else {
588 // The maximum possible number of young regions will not fit within
589 // the target pause time so let's search....
590
591 size_t diff = (max_young_length - min_young_length) / 2;
592 max_young_length = min_young_length + diff;
593
594 while (max_young_length > min_young_length) {
595 if (predict_will_fit(max_young_length, base_time_ms,
596 init_free_regions, target_pause_time_ms)) {
597
598 // The current max young length will fit within the target
599 // pause time. Note we do not exit the loop here. By setting
600 // min = max, and then increasing the max below means that
601 // we will continue searching for an upper bound in the
602 // range [max..max+diff]
603 min_young_length = max_young_length;
604 }
605 diff = (max_young_length - min_young_length) / 2;
606 max_young_length = min_young_length + diff;
607 }
608 // the above loop found a maximal young length that will fit
609 // within the target pause time.
610 }
611 assert(min_young_length <= abs_max_young_length, "just checking");
612 }
613 final_young_length = min_young_length;
614 }
615 }
616 // and we're done!
617
618 // we should have at least one region in the target young length
619 _young_list_target_length =
620 final_young_length + _recorded_survivor_regions;
621
622 // let's keep an eye of how long we spend on this calculation
623 // right now, I assume that we'll print it when we need it; we
624 // should really adde it to the breakdown of a pause
625 double end_time_sec = os::elapsedTime();
626 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
627
628 #ifdef TRACE_CALC_YOUNG_LENGTH
629 // leave this in for debugging, just in case
630 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
631 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
632 target_pause_time_ms,
633 _young_list_target_length
634 elapsed_time_ms,
635 full_young_gcs() ? "full" : "partial",
636 during_initial_mark_pause() ? " i-m" : "",
637 _in_marking_window,
638 _in_marking_window_im);
639 #endif // TRACE_CALC_YOUNG_LENGTH
640
641 if (_young_list_target_length < _young_list_min_length) {
642 // bummer; this means that, if we do a pause when the maximal
643 // length dictates, we'll violate the pause spacing target (the
644 // min length was calculate based on the application's current
645 // alloc rate);
646
647 // so, we have to bite the bullet, and allocate the minimum
648 // number. We'll violate our target, but we just can't meet it.
649
650 #ifdef TRACE_CALC_YOUNG_LENGTH
651 // leave this in for debugging, just in case
652 gclog_or_tty->print_cr("adjusted target length from "
653 SIZE_FORMAT " to " SIZE_FORMAT,
654 _young_list_target_length, _young_list_min_length);
655 #endif // TRACE_CALC_YOUNG_LENGTH
656
657 _young_list_target_length = _young_list_min_length;
658 }
659 } else {
660 // we are in a partially-young mode or we've run out of regions (due
661 // to evacuation failure)
662
663 #ifdef TRACE_CALC_YOUNG_LENGTH
664 // leave this in for debugging, just in case
665 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
666 _young_list_min_length);
667 #endif // TRACE_CALC_YOUNG_LENGTH
668 // we'll do the pause as soon as possible by choosing the minimum
669 _young_list_target_length = _young_list_min_length;
670 }
671
672 _rs_lengths_prediction = rs_lengths;
673 }
674
675 // This is used by: calculate_young_list_target_length(rs_length). It
676 // returns true iff:
677 // the predicted pause time for the given young list will not overflow
678 // the target pause time
679 // and:
680 // the predicted amount of surviving data will not overflow the
681 // the amount of free space available for survivor regions.
682 //
683 bool
684 G1CollectorPolicy::predict_will_fit(size_t young_length,
685 double base_time_ms,
686 size_t init_free_regions,
687 double target_pause_time_ms) {
688
689 if (young_length >= init_free_regions)
690 // end condition 1: not enough space for the young regions
691 return false;
692
693 double accum_surv_rate_adj = 0.0;
694 double accum_surv_rate =
695 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
696
697 size_t bytes_to_copy =
698 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
699
700 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
701
702 double young_other_time_ms =
703 predict_young_other_time_ms(young_length);
704
705 double pause_time_ms =
706 base_time_ms + copy_time_ms + young_other_time_ms;
707
708 if (pause_time_ms > target_pause_time_ms)
709 // end condition 2: over the target pause time
710 return false;
711
712 size_t free_bytes =
713 (init_free_regions - young_length) * HeapRegion::GrainBytes;
714
715 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
716 // end condition 3: out of to-space (conservatively)
717 return false;
718
719 // success!
720 return true;
721 }
722
723 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
724 double survivor_regions_evac_time = 0.0;
725 for (HeapRegion * r = _recorded_survivor_head;
726 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
727 r = r->get_next_young_region()) {
728 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
729 }
730 return survivor_regions_evac_time;
731 }
732
733 void G1CollectorPolicy::check_prediction_validity() {
734 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
735
736 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
737 if (rs_lengths > _rs_lengths_prediction) {
738 // add 10% to avoid having to recalculate often
739 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
740 calculate_young_list_target_length(rs_lengths_prediction);
741 }
742 }
743
744 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
745 bool is_tlab,
746 bool* gc_overhead_limit_was_exceeded) {
747 guarantee(false, "Not using this policy feature yet.");
748 return NULL;
749 }
750
751 // This method controls how a collector handles one or more
752 // of its generations being fully allocated.
753 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
754 bool is_tlab) {
755 guarantee(false, "Not using this policy feature yet.");
756 return NULL;
757 }
758
759
760 #ifndef PRODUCT
761 bool G1CollectorPolicy::verify_young_ages() {
762 HeapRegion* head = _g1->young_list()->first_region();
763 return
764 verify_young_ages(head, _short_lived_surv_rate_group);
765 // also call verify_young_ages on any additional surv rate groups
766 }
767
768 bool
769 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
770 SurvRateGroup *surv_rate_group) {
771 guarantee( surv_rate_group != NULL, "pre-condition" );
772
773 const char* name = surv_rate_group->name();
774 bool ret = true;
775 int prev_age = -1;
776
777 for (HeapRegion* curr = head;
778 curr != NULL;
779 curr = curr->get_next_young_region()) {
780 SurvRateGroup* group = curr->surv_rate_group();
781 if (group == NULL && !curr->is_survivor()) {
782 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
783 ret = false;
784 }
785
786 if (surv_rate_group == group) {
787 int age = curr->age_in_surv_rate_group();
788
789 if (age < 0) {
790 gclog_or_tty->print_cr("## %s: encountered negative age", name);
791 ret = false;
792 }
793
794 if (age <= prev_age) {
795 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
796 "(%d, %d)", name, age, prev_age);
797 ret = false;
798 }
799 prev_age = age;
800 }
801 }
802
803 return ret;
804 }
805 #endif // PRODUCT
806
807 void G1CollectorPolicy::record_full_collection_start() {
808 _cur_collection_start_sec = os::elapsedTime();
809 // Release the future to-space so that it is available for compaction into.
810 _g1->set_full_collection();
811 }
812
813 void G1CollectorPolicy::record_full_collection_end() {
814 // Consider this like a collection pause for the purposes of allocation
815 // since last pause.
816 double end_sec = os::elapsedTime();
817 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
818 double full_gc_time_ms = full_gc_time_sec * 1000.0;
819
820 _all_full_gc_times_ms->add(full_gc_time_ms);
821
822 update_recent_gc_times(end_sec, full_gc_time_ms);
823
824 _g1->clear_full_collection();
825
826 // "Nuke" the heuristics that control the fully/partially young GC
827 // transitions and make sure we start with fully young GCs after the
828 // Full GC.
829 set_full_young_gcs(true);
830 _last_full_young_gc = false;
831 _should_revert_to_full_young_gcs = false;
832 clear_initiate_conc_mark_if_possible();
833 clear_during_initial_mark_pause();
834 _known_garbage_bytes = 0;
835 _known_garbage_ratio = 0.0;
836 _in_marking_window = false;
837 _in_marking_window_im = false;
838
839 _short_lived_surv_rate_group->start_adding_regions();
840 // also call this on any additional surv rate groups
841
842 record_survivor_regions(0, NULL, NULL);
843
844 _prev_region_num_young = _region_num_young;
845 _prev_region_num_tenured = _region_num_tenured;
846
847 _free_regions_at_end_of_collection = _g1->free_regions();
848 // Reset survivors SurvRateGroup.
849 _survivor_surv_rate_group->reset();
850 calculate_young_list_min_length();
851 calculate_young_list_target_length();
852 }
853
854 void G1CollectorPolicy::record_stop_world_start() {
855 _stop_world_start = os::elapsedTime();
856 }
857
858 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
859 size_t start_used) {
860 if (PrintGCDetails) {
861 gclog_or_tty->stamp(PrintGCTimeStamps);
862 gclog_or_tty->print("[GC pause");
863 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
864 }
865
866 assert(_g1->used() == _g1->recalculate_used(),
867 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
868 _g1->used(), _g1->recalculate_used()));
869
870 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
871 _all_stop_world_times_ms->add(s_w_t_ms);
872 _stop_world_start = 0.0;
873
874 _cur_collection_start_sec = start_time_sec;
875 _cur_collection_pause_used_at_start_bytes = start_used;
876 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
877 _pending_cards = _g1->pending_card_num();
878 _max_pending_cards = _g1->max_pending_card_num();
879
880 _bytes_in_collection_set_before_gc = 0;
881 _bytes_copied_during_gc = 0;
882
883 YoungList* young_list = _g1->young_list();
884 _eden_bytes_before_gc = young_list->eden_used_bytes();
885 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
886 _capacity_before_gc = _g1->capacity();
887
888 #ifdef DEBUG
889 // initialise these to something well known so that we can spot
890 // if they are not set properly
891
892 for (int i = 0; i < _parallel_gc_threads; ++i) {
893 _par_last_gc_worker_start_times_ms[i] = -1234.0;
894 _par_last_ext_root_scan_times_ms[i] = -1234.0;
895 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
896 _par_last_update_rs_times_ms[i] = -1234.0;
897 _par_last_update_rs_processed_buffers[i] = -1234.0;
898 _par_last_scan_rs_times_ms[i] = -1234.0;
899 _par_last_obj_copy_times_ms[i] = -1234.0;
900 _par_last_termination_times_ms[i] = -1234.0;
901 _par_last_termination_attempts[i] = -1234.0;
902 _par_last_gc_worker_end_times_ms[i] = -1234.0;
903 _par_last_gc_worker_times_ms[i] = -1234.0;
904 }
905 #endif
906
907 for (int i = 0; i < _aux_num; ++i) {
908 _cur_aux_times_ms[i] = 0.0;
909 _cur_aux_times_set[i] = false;
910 }
911
912 _satb_drain_time_set = false;
913 _last_satb_drain_processed_buffers = -1;
914
915 _last_young_gc_full = false;
916
917 // do that for any other surv rate groups
918 _short_lived_surv_rate_group->stop_adding_regions();
919 _survivors_age_table.clear();
920
921 assert( verify_young_ages(), "region age verification" );
922 }
923
924 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
925 _mark_closure_time_ms = mark_closure_time_ms;
926 }
927
928 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
929 mark_init_elapsed_time_ms) {
930 _during_marking = true;
931 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
932 clear_during_initial_mark_pause();
933 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
934 }
935
936 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
937 _mark_remark_start_sec = os::elapsedTime();
938 _during_marking = false;
939 }
940
941 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
942 double end_time_sec = os::elapsedTime();
943 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
944 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
945 _cur_mark_stop_world_time_ms += elapsed_time_ms;
946 _prev_collection_pause_end_ms += elapsed_time_ms;
947
948 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
949 }
950
951 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
952 _mark_cleanup_start_sec = os::elapsedTime();
953 }
954
955 void
956 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
957 size_t max_live_bytes) {
958 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
959 record_concurrent_mark_cleanup_end_work2();
960 }
961
962 void
963 G1CollectorPolicy::
964 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
965 size_t max_live_bytes) {
966 if (_n_marks < 2) _n_marks++;
967 if (G1PolicyVerbose > 0)
968 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
969 " (of " SIZE_FORMAT " MB heap).",
970 max_live_bytes/M, _g1->capacity()/M);
971 }
972
973 // The important thing about this is that it includes "os::elapsedTime".
974 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
975 double end_time_sec = os::elapsedTime();
976 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
977 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
978 _cur_mark_stop_world_time_ms += elapsed_time_ms;
979 _prev_collection_pause_end_ms += elapsed_time_ms;
980
981 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
982
983 _num_markings++;
984
985 // We did a marking, so reset the "since_last_mark" variables.
986 double considerConcMarkCost = 1.0;
987 // If there are available processors, concurrent activity is free...
988 if (Threads::number_of_non_daemon_threads() * 2 <
989 os::active_processor_count()) {
990 considerConcMarkCost = 0.0;
991 }
992 _n_pauses_at_mark_end = _n_pauses;
993 _n_marks_since_last_pause++;
994 }
995
996 void
997 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
998 _should_revert_to_full_young_gcs = false;
999 _last_full_young_gc = true;
1000 _in_marking_window = false;
1001 if (adaptive_young_list_length())
1002 calculate_young_list_target_length();
1003 }
1004
1005 void G1CollectorPolicy::record_concurrent_pause() {
1006 if (_stop_world_start > 0.0) {
1007 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
1008 _all_yield_times_ms->add(yield_ms);
1009 }
1010 }
1011
1012 void G1CollectorPolicy::record_concurrent_pause_end() {
1013 }
1014
1015 template<class T>
1016 T sum_of(T* sum_arr, int start, int n, int N) {
1017 T sum = (T)0;
1018 for (int i = 0; i < n; i++) {
1019 int j = (start + i) % N;
1020 sum += sum_arr[j];
1021 }
1022 return sum;
1023 }
1024
1025 void G1CollectorPolicy::print_par_stats(int level,
1026 const char* str,
1027 double* data) {
1028 double min = data[0], max = data[0];
1029 double total = 0.0;
1030 LineBuffer buf(level);
1031 buf.append("[%s (ms):", str);
1032 for (uint i = 0; i < ParallelGCThreads; ++i) {
1033 double val = data[i];
1034 if (val < min)
1035 min = val;
1036 if (val > max)
1037 max = val;
1038 total += val;
1039 buf.append(" %3.1lf", val);
1040 }
1041 buf.append_and_print_cr("");
1042 double avg = total / (double) ParallelGCThreads;
1043 buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
1044 avg, min, max, max - min);
1045 }
1046
1047 void G1CollectorPolicy::print_par_sizes(int level,
1048 const char* str,
1049 double* data) {
1050 double min = data[0], max = data[0];
1051 double total = 0.0;
1052 LineBuffer buf(level);
1053 buf.append("[%s :", str);
1054 for (uint i = 0; i < ParallelGCThreads; ++i) {
1055 double val = data[i];
1056 if (val < min)
1057 min = val;
1058 if (val > max)
1059 max = val;
1060 total += val;
1061 buf.append(" %d", (int) val);
1062 }
1063 buf.append_and_print_cr("");
1064 double avg = total / (double) ParallelGCThreads;
1065 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1066 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1067 }
1068
1069 void G1CollectorPolicy::print_stats (int level,
1070 const char* str,
1071 double value) {
1072 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1073 }
1074
1075 void G1CollectorPolicy::print_stats (int level,
1076 const char* str,
1077 int value) {
1078 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1079 }
1080
1081 double G1CollectorPolicy::avg_value (double* data) {
1082 if (G1CollectedHeap::use_parallel_gc_threads()) {
1083 double ret = 0.0;
1084 for (uint i = 0; i < ParallelGCThreads; ++i)
1085 ret += data[i];
1086 return ret / (double) ParallelGCThreads;
1087 } else {
1088 return data[0];
1089 }
1090 }
1091
1092 double G1CollectorPolicy::max_value (double* data) {
1093 if (G1CollectedHeap::use_parallel_gc_threads()) {
1094 double ret = data[0];
1095 for (uint i = 1; i < ParallelGCThreads; ++i)
1096 if (data[i] > ret)
1097 ret = data[i];
1098 return ret;
1099 } else {
1100 return data[0];
1101 }
1102 }
1103
1104 double G1CollectorPolicy::sum_of_values (double* data) {
1105 if (G1CollectedHeap::use_parallel_gc_threads()) {
1106 double sum = 0.0;
1107 for (uint i = 0; i < ParallelGCThreads; i++)
1108 sum += data[i];
1109 return sum;
1110 } else {
1111 return data[0];
1112 }
1113 }
1114
1115 double G1CollectorPolicy::max_sum (double* data1,
1116 double* data2) {
1117 double ret = data1[0] + data2[0];
1118
1119 if (G1CollectedHeap::use_parallel_gc_threads()) {
1120 for (uint i = 1; i < ParallelGCThreads; ++i) {
1121 double data = data1[i] + data2[i];
1122 if (data > ret)
1123 ret = data;
1124 }
1125 }
1126 return ret;
1127 }
1128
1129 // Anything below that is considered to be zero
1130 #define MIN_TIMER_GRANULARITY 0.0000001
1131
1132 void G1CollectorPolicy::record_collection_pause_end() {
1133 double end_time_sec = os::elapsedTime();
1134 double elapsed_ms = _last_pause_time_ms;
1135 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1136 size_t rs_size =
1137 _cur_collection_pause_used_regions_at_start - collection_set_size();
1138 size_t cur_used_bytes = _g1->used();
1139 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1140 bool last_pause_included_initial_mark = false;
1141 bool update_stats = !_g1->evacuation_failed();
1142
1143 #ifndef PRODUCT
1144 if (G1YoungSurvRateVerbose) {
1145 gclog_or_tty->print_cr("");
1146 _short_lived_surv_rate_group->print();
1147 // do that for any other surv rate groups too
1148 }
1149 #endif // PRODUCT
1150
1151 last_pause_included_initial_mark = during_initial_mark_pause();
1152 if (last_pause_included_initial_mark)
1153 record_concurrent_mark_init_end_pre(0.0);
1154
1155 size_t min_used_targ =
1156 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1157
1158
1159 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1160 assert(!last_pause_included_initial_mark, "invariant");
1161 if (cur_used_bytes > min_used_targ &&
1162 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1163 assert(!during_initial_mark_pause(), "we should not see this here");
1164
1165 // Note: this might have already been set, if during the last
1166 // pause we decided to start a cycle but at the beginning of
1167 // this pause we decided to postpone it. That's OK.
1168 set_initiate_conc_mark_if_possible();
1169 }
1170 }
1171
1172 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1173
1174 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1175 end_time_sec, false);
1176
1177 guarantee(_cur_collection_pause_used_regions_at_start >=
1178 collection_set_size(),
1179 "Negative RS size?");
1180
1181 // This assert is exempted when we're doing parallel collection pauses,
1182 // because the fragmentation caused by the parallel GC allocation buffers
1183 // can lead to more memory being used during collection than was used
1184 // before. Best leave this out until the fragmentation problem is fixed.
1185 // Pauses in which evacuation failed can also lead to negative
1186 // collections, since no space is reclaimed from a region containing an
1187 // object whose evacuation failed.
1188 // Further, we're now always doing parallel collection. But I'm still
1189 // leaving this here as a placeholder for a more precise assertion later.
1190 // (DLD, 10/05.)
1191 assert((true || parallel) // Always using GC LABs now.
1192 || _g1->evacuation_failed()
1193 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1194 "Negative collection");
1195
1196 size_t freed_bytes =
1197 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1198 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1199
1200 double survival_fraction =
1201 (double)surviving_bytes/
1202 (double)_collection_set_bytes_used_before;
1203
1204 _n_pauses++;
1205
1206 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1207 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1208 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1209 double update_rs_processed_buffers =
1210 sum_of_values(_par_last_update_rs_processed_buffers);
1211 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1212 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1213 double termination_time = avg_value(_par_last_termination_times_ms);
1214
1215 double parallel_known_time = update_rs_time +
1216 ext_root_scan_time +
1217 mark_stack_scan_time +
1218 scan_rs_time +
1219 obj_copy_time +
1220 termination_time;
1221
1222 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1223
1224 PauseSummary* summary = _summary;
1225
1226 if (update_stats) {
1227 _recent_rs_scan_times_ms->add(scan_rs_time);
1228 _recent_pause_times_ms->add(elapsed_ms);
1229 _recent_rs_sizes->add(rs_size);
1230
1231 MainBodySummary* body_summary = summary->main_body_summary();
1232 guarantee(body_summary != NULL, "should not be null!");
1233
1234 if (_satb_drain_time_set)
1235 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1236 else
1237 body_summary->record_satb_drain_time_ms(0.0);
1238
1239 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1240 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1241 body_summary->record_update_rs_time_ms(update_rs_time);
1242 body_summary->record_scan_rs_time_ms(scan_rs_time);
1243 body_summary->record_obj_copy_time_ms(obj_copy_time);
1244 if (parallel) {
1245 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1246 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1247 body_summary->record_termination_time_ms(termination_time);
1248 body_summary->record_parallel_other_time_ms(parallel_other_time);
1249 }
1250 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1251
1252 // We exempt parallel collection from this check because Alloc Buffer
1253 // fragmentation can produce negative collections. Same with evac
1254 // failure.
1255 // Further, we're now always doing parallel collection. But I'm still
1256 // leaving this here as a placeholder for a more precise assertion later.
1257 // (DLD, 10/05.
1258 assert((true || parallel)
1259 || _g1->evacuation_failed()
1260 || surviving_bytes <= _collection_set_bytes_used_before,
1261 "Or else negative collection!");
1262 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1263 _recent_CS_bytes_surviving->add(surviving_bytes);
1264
1265 // this is where we update the allocation rate of the application
1266 double app_time_ms =
1267 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1268 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1269 // This usually happens due to the timer not having the required
1270 // granularity. Some Linuxes are the usual culprits.
1271 // We'll just set it to something (arbitrarily) small.
1272 app_time_ms = 1.0;
1273 }
1274 size_t regions_allocated =
1275 (_region_num_young - _prev_region_num_young) +
1276 (_region_num_tenured - _prev_region_num_tenured);
1277 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1278 _alloc_rate_ms_seq->add(alloc_rate_ms);
1279 _prev_region_num_young = _region_num_young;
1280 _prev_region_num_tenured = _region_num_tenured;
1281
1282 double interval_ms =
1283 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1284 update_recent_gc_times(end_time_sec, elapsed_ms);
1285 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1286 if (recent_avg_pause_time_ratio() < 0.0 ||
1287 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1288 #ifndef PRODUCT
1289 // Dump info to allow post-facto debugging
1290 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1291 gclog_or_tty->print_cr("-------------------------------------------");
1292 gclog_or_tty->print_cr("Recent GC Times (ms):");
1293 _recent_gc_times_ms->dump();
1294 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1295 _recent_prev_end_times_for_all_gcs_sec->dump();
1296 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1297 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1298 // In debug mode, terminate the JVM if the user wants to debug at this point.
1299 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1300 #endif // !PRODUCT
1301 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1302 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1303 if (_recent_avg_pause_time_ratio < 0.0) {
1304 _recent_avg_pause_time_ratio = 0.0;
1305 } else {
1306 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1307 _recent_avg_pause_time_ratio = 1.0;
1308 }
1309 }
1310 }
1311
1312 if (G1PolicyVerbose > 1) {
1313 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1314 }
1315
1316 if (G1PolicyVerbose > 1) {
1317 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1318 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1319 " |RS|: " SIZE_FORMAT,
1320 elapsed_ms, recent_avg_time_for_pauses_ms(),
1321 scan_rs_time, recent_avg_time_for_rs_scan_ms(),
1322 rs_size);
1323
1324 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1325 " At end " SIZE_FORMAT "K\n"
1326 " garbage : " SIZE_FORMAT "K"
1327 " of " SIZE_FORMAT "K\n"
1328 " survival : %6.2f%% (%6.2f%% avg)",
1329 _cur_collection_pause_used_at_start_bytes/K,
1330 _g1->used()/K, freed_bytes/K,
1331 _collection_set_bytes_used_before/K,
1332 survival_fraction*100.0,
1333 recent_avg_survival_fraction()*100.0);
1334 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1335 recent_avg_pause_time_ratio() * 100.0);
1336 }
1337
1338 double other_time_ms = elapsed_ms;
1339
1340 if (_satb_drain_time_set) {
1341 other_time_ms -= _cur_satb_drain_time_ms;
1342 }
1343
1344 if (parallel) {
1345 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1346 } else {
1347 other_time_ms -=
1348 update_rs_time +
1349 ext_root_scan_time + mark_stack_scan_time +
1350 scan_rs_time + obj_copy_time;
1351 }
1352
1353 if (PrintGCDetails) {
1354 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1355 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1356 elapsed_ms / 1000.0);
1357
1358 if (_satb_drain_time_set) {
1359 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1360 }
1361 if (_last_satb_drain_processed_buffers >= 0) {
1362 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1363 }
1364 if (parallel) {
1365 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1366 print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
1367 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1368 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1369 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1370 print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
1371 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1372 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1373 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1374 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1375 print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);
1376
1377 for (int i = 0; i < _parallel_gc_threads; i++) {
1378 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
1379 }
1380 print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);
1381
1382 print_stats(2, "Parallel Other", parallel_other_time);
1383 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1384 } else {
1385 print_stats(1, "Update RS", update_rs_time);
1386 print_stats(2, "Processed Buffers",
1387 (int)update_rs_processed_buffers);
1388 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1389 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1390 print_stats(1, "Scan RS", scan_rs_time);
1391 print_stats(1, "Object Copying", obj_copy_time);
1392 }
1393 #ifndef PRODUCT
1394 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1395 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1396 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1397 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1398 if (_num_cc_clears > 0) {
1399 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1400 }
1401 #endif
1402 print_stats(1, "Other", other_time_ms);
1403 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1404
1405 for (int i = 0; i < _aux_num; ++i) {
1406 if (_cur_aux_times_set[i]) {
1407 char buffer[96];
1408 sprintf(buffer, "Aux%d", i);
1409 print_stats(1, buffer, _cur_aux_times_ms[i]);
1410 }
1411 }
1412 }
1413
1414 _all_pause_times_ms->add(elapsed_ms);
1415 if (update_stats) {
1416 summary->record_total_time_ms(elapsed_ms);
1417 summary->record_other_time_ms(other_time_ms);
1418 }
1419 for (int i = 0; i < _aux_num; ++i)
1420 if (_cur_aux_times_set[i])
1421 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1422
1423 // Reset marks-between-pauses counter.
1424 _n_marks_since_last_pause = 0;
1425
1426 // Update the efficiency-since-mark vars.
1427 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1428 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1429 // This usually happens due to the timer not having the required
1430 // granularity. Some Linuxes are the usual culprits.
1431 // We'll just set it to something (arbitrarily) small.
1432 proc_ms = 1.0;
1433 }
1434 double cur_efficiency = (double) freed_bytes / proc_ms;
1435
1436 bool new_in_marking_window = _in_marking_window;
1437 bool new_in_marking_window_im = false;
1438 if (during_initial_mark_pause()) {
1439 new_in_marking_window = true;
1440 new_in_marking_window_im = true;
1441 }
1442
1443 if (_last_full_young_gc) {
1444 set_full_young_gcs(false);
1445 _last_full_young_gc = false;
1446 }
1447
1448 if ( !_last_young_gc_full ) {
1449 if ( _should_revert_to_full_young_gcs ||
1450 _known_garbage_ratio < 0.05 ||
1451 (adaptive_young_list_length() &&
1452 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1453 set_full_young_gcs(true);
1454 }
1455 }
1456 _should_revert_to_full_young_gcs = false;
1457
1458 if (_last_young_gc_full && !_during_marking) {
1459 _young_gc_eff_seq->add(cur_efficiency);
1460 }
1461
1462 _short_lived_surv_rate_group->start_adding_regions();
1463 // do that for any other surv rate groupsx
1464
1465 // <NEW PREDICTION>
1466
1467 if (update_stats) {
1468 double pause_time_ms = elapsed_ms;
1469
1470 size_t diff = 0;
1471 if (_max_pending_cards >= _pending_cards)
1472 diff = _max_pending_cards - _pending_cards;
1473 _pending_card_diff_seq->add((double) diff);
1474
1475 double cost_per_card_ms = 0.0;
1476 if (_pending_cards > 0) {
1477 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1478 _cost_per_card_ms_seq->add(cost_per_card_ms);
1479 }
1480
1481 size_t cards_scanned = _g1->cards_scanned();
1482
1483 double cost_per_entry_ms = 0.0;
1484 if (cards_scanned > 10) {
1485 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1486 if (_last_young_gc_full)
1487 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1488 else
1489 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1490 }
1491
1492 if (_max_rs_lengths > 0) {
1493 double cards_per_entry_ratio =
1494 (double) cards_scanned / (double) _max_rs_lengths;
1495 if (_last_young_gc_full)
1496 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1497 else
1498 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1499 }
1500
1501 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1502 if (rs_length_diff >= 0)
1503 _rs_length_diff_seq->add((double) rs_length_diff);
1504
1505 size_t copied_bytes = surviving_bytes;
1506 double cost_per_byte_ms = 0.0;
1507 if (copied_bytes > 0) {
1508 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1509 if (_in_marking_window)
1510 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1511 else
1512 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1513 }
1514
1515 double all_other_time_ms = pause_time_ms -
1516 (update_rs_time + scan_rs_time + obj_copy_time +
1517 _mark_closure_time_ms + termination_time);
1518
1519 double young_other_time_ms = 0.0;
1520 if (_recorded_young_regions > 0) {
1521 young_other_time_ms =
1522 _recorded_young_cset_choice_time_ms +
1523 _recorded_young_free_cset_time_ms;
1524 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1525 (double) _recorded_young_regions);
1526 }
1527 double non_young_other_time_ms = 0.0;
1528 if (_recorded_non_young_regions > 0) {
1529 non_young_other_time_ms =
1530 _recorded_non_young_cset_choice_time_ms +
1531 _recorded_non_young_free_cset_time_ms;
1532
1533 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1534 (double) _recorded_non_young_regions);
1535 }
1536
1537 double constant_other_time_ms = all_other_time_ms -
1538 (young_other_time_ms + non_young_other_time_ms);
1539 _constant_other_time_ms_seq->add(constant_other_time_ms);
1540
1541 double survival_ratio = 0.0;
1542 if (_bytes_in_collection_set_before_gc > 0) {
1543 survival_ratio = (double) _bytes_copied_during_gc /
1544 (double) _bytes_in_collection_set_before_gc;
1545 }
1546
1547 _pending_cards_seq->add((double) _pending_cards);
1548 _scanned_cards_seq->add((double) cards_scanned);
1549 _rs_lengths_seq->add((double) _max_rs_lengths);
1550
1551 double expensive_region_limit_ms =
1552 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1553 if (expensive_region_limit_ms < 0.0) {
1554 // this means that the other time was predicted to be longer than
1555 // than the max pause time
1556 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1557 }
1558 _expensive_region_limit_ms = expensive_region_limit_ms;
1559
1560 if (PREDICTIONS_VERBOSE) {
1561 gclog_or_tty->print_cr("");
1562 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1563 "REGIONS %d %d %d "
1564 "PENDING_CARDS %d %d "
1565 "CARDS_SCANNED %d %d "
1566 "RS_LENGTHS %d %d "
1567 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1568 "SURVIVAL_RATIO %1.6lf %1.6lf "
1569 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1570 "OTHER_YOUNG %1.6lf %1.6lf "
1571 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1572 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1573 "ELAPSED %1.6lf %1.6lf ",
1574 _cur_collection_start_sec,
1575 (!_last_young_gc_full) ? 2 :
1576 (last_pause_included_initial_mark) ? 1 : 0,
1577 _recorded_region_num,
1578 _recorded_young_regions,
1579 _recorded_non_young_regions,
1580 _predicted_pending_cards, _pending_cards,
1581 _predicted_cards_scanned, cards_scanned,
1582 _predicted_rs_lengths, _max_rs_lengths,
1583 _predicted_rs_update_time_ms, update_rs_time,
1584 _predicted_rs_scan_time_ms, scan_rs_time,
1585 _predicted_survival_ratio, survival_ratio,
1586 _predicted_object_copy_time_ms, obj_copy_time,
1587 _predicted_constant_other_time_ms, constant_other_time_ms,
1588 _predicted_young_other_time_ms, young_other_time_ms,
1589 _predicted_non_young_other_time_ms,
1590 non_young_other_time_ms,
1591 _vtime_diff_ms, termination_time,
1592 _predicted_pause_time_ms, elapsed_ms);
1593 }
1594
1595 if (G1PolicyVerbose > 0) {
1596 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1597 _predicted_pause_time_ms,
1598 (_within_target) ? "within" : "outside",
1599 elapsed_ms);
1600 }
1601
1602 }
1603
1604 _in_marking_window = new_in_marking_window;
1605 _in_marking_window_im = new_in_marking_window_im;
1606 _free_regions_at_end_of_collection = _g1->free_regions();
1607 calculate_young_list_min_length();
1608 calculate_young_list_target_length();
1609
1610 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1611 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1612 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1613 // </NEW PREDICTION>
1614 }
1615
1616 #define EXT_SIZE_FORMAT "%d%s"
1617 #define EXT_SIZE_PARAMS(bytes) \
1618 byte_size_in_proper_unit((bytes)), \
1619 proper_unit_for_byte_size((bytes))
1620
1621 void G1CollectorPolicy::print_heap_transition() {
1622 if (PrintGCDetails) {
1623 YoungList* young_list = _g1->young_list();
1624 size_t eden_bytes = young_list->eden_used_bytes();
1625 size_t survivor_bytes = young_list->survivor_used_bytes();
1626 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1627 size_t used = _g1->used();
1628 size_t capacity = _g1->capacity();
1629
1630 gclog_or_tty->print_cr(
1631 " [Eden: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1632 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1633 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1634 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1635 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1636 EXT_SIZE_PARAMS(eden_bytes),
1637 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1638 EXT_SIZE_PARAMS(survivor_bytes),
1639 EXT_SIZE_PARAMS(used_before_gc),
1640 EXT_SIZE_PARAMS(_capacity_before_gc),
1641 EXT_SIZE_PARAMS(used),
1642 EXT_SIZE_PARAMS(capacity));
1643 } else if (PrintGC) {
1644 _g1->print_size_transition(gclog_or_tty,
1645 _cur_collection_pause_used_at_start_bytes,
1646 _g1->used(), _g1->capacity());
1647 }
1648 }
1649
1650 // <NEW PREDICTION>
1651
1652 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1653 double update_rs_processed_buffers,
1654 double goal_ms) {
1655 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1656 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1657
1658 if (G1UseAdaptiveConcRefinement) {
1659 const int k_gy = 3, k_gr = 6;
1660 const double inc_k = 1.1, dec_k = 0.9;
1661
1662 int g = cg1r->green_zone();
1663 if (update_rs_time > goal_ms) {
1664 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1665 } else {
1666 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1667 g = (int)MAX2(g * inc_k, g + 1.0);
1668 }
1669 }
1670 // Change the refinement threads params
1671 cg1r->set_green_zone(g);
1672 cg1r->set_yellow_zone(g * k_gy);
1673 cg1r->set_red_zone(g * k_gr);
1674 cg1r->reinitialize_threads();
1675
1676 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1677 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1678 cg1r->yellow_zone());
1679 // Change the barrier params
1680 dcqs.set_process_completed_threshold(processing_threshold);
1681 dcqs.set_max_completed_queue(cg1r->red_zone());
1682 }
1683
1684 int curr_queue_size = dcqs.completed_buffers_num();
1685 if (curr_queue_size >= cg1r->yellow_zone()) {
1686 dcqs.set_completed_queue_padding(curr_queue_size);
1687 } else {
1688 dcqs.set_completed_queue_padding(0);
1689 }
1690 dcqs.notify_if_necessary();
1691 }
1692
1693 double
1694 G1CollectorPolicy::
1695 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1696 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1697
1698 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1699 size_t young_num = g1h->young_list()->length();
1700 if (young_num == 0)
1701 return 0.0;
1702
1703 young_num += adjustment;
1704 size_t pending_cards = predict_pending_cards();
1705 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1706 predict_rs_length_diff();
1707 size_t card_num;
1708 if (full_young_gcs())
1709 card_num = predict_young_card_num(rs_lengths);
1710 else
1711 card_num = predict_non_young_card_num(rs_lengths);
1712 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1713 double accum_yg_surv_rate =
1714 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1715
1716 size_t bytes_to_copy =
1717 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1718
1719 return
1720 predict_rs_update_time_ms(pending_cards) +
1721 predict_rs_scan_time_ms(card_num) +
1722 predict_object_copy_time_ms(bytes_to_copy) +
1723 predict_young_other_time_ms(young_num) +
1724 predict_constant_other_time_ms();
1725 }
1726
1727 double
1728 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1729 size_t rs_length = predict_rs_length_diff();
1730 size_t card_num;
1731 if (full_young_gcs())
1732 card_num = predict_young_card_num(rs_length);
1733 else
1734 card_num = predict_non_young_card_num(rs_length);
1735 return predict_base_elapsed_time_ms(pending_cards, card_num);
1736 }
1737
1738 double
1739 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1740 size_t scanned_cards) {
1741 return
1742 predict_rs_update_time_ms(pending_cards) +
1743 predict_rs_scan_time_ms(scanned_cards) +
1744 predict_constant_other_time_ms();
1745 }
1746
1747 double
1748 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1749 bool young) {
1750 size_t rs_length = hr->rem_set()->occupied();
1751 size_t card_num;
1752 if (full_young_gcs())
1753 card_num = predict_young_card_num(rs_length);
1754 else
1755 card_num = predict_non_young_card_num(rs_length);
1756 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1757
1758 double region_elapsed_time_ms =
1759 predict_rs_scan_time_ms(card_num) +
1760 predict_object_copy_time_ms(bytes_to_copy);
1761
1762 if (young)
1763 region_elapsed_time_ms += predict_young_other_time_ms(1);
1764 else
1765 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1766
1767 return region_elapsed_time_ms;
1768 }
1769
1770 size_t
1771 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1772 size_t bytes_to_copy;
1773 if (hr->is_marked())
1774 bytes_to_copy = hr->max_live_bytes();
1775 else {
1776 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1777 "invariant" );
1778 int age = hr->age_in_surv_rate_group();
1779 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1780 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1781 }
1782
1783 return bytes_to_copy;
1784 }
1785
1786 void
1787 G1CollectorPolicy::start_recording_regions() {
1788 _recorded_rs_lengths = 0;
1789 _recorded_young_regions = 0;
1790 _recorded_non_young_regions = 0;
1791
1792 #if PREDICTIONS_VERBOSE
1793 _recorded_marked_bytes = 0;
1794 _recorded_young_bytes = 0;
1795 _predicted_bytes_to_copy = 0;
1796 _predicted_rs_lengths = 0;
1797 _predicted_cards_scanned = 0;
1798 #endif // PREDICTIONS_VERBOSE
1799 }
1800
1801 void
1802 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1803 #if PREDICTIONS_VERBOSE
1804 if (!young) {
1805 _recorded_marked_bytes += hr->max_live_bytes();
1806 }
1807 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1808 #endif // PREDICTIONS_VERBOSE
1809
1810 size_t rs_length = hr->rem_set()->occupied();
1811 _recorded_rs_lengths += rs_length;
1812 }
1813
1814 void
1815 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1816 assert(!hr->is_young(), "should not call this");
1817 ++_recorded_non_young_regions;
1818 record_cset_region_info(hr, false);
1819 }
1820
1821 void
1822 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1823 _recorded_young_regions = n_regions;
1824 }
1825
1826 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1827 #if PREDICTIONS_VERBOSE
1828 _recorded_young_bytes = bytes;
1829 #endif // PREDICTIONS_VERBOSE
1830 }
1831
1832 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1833 _recorded_rs_lengths = rs_lengths;
1834 }
1835
1836 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1837 _predicted_bytes_to_copy = bytes;
1838 }
1839
1840 void
1841 G1CollectorPolicy::end_recording_regions() {
1842 // The _predicted_pause_time_ms field is referenced in code
1843 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1844 _predicted_pause_time_ms = -1.0;
1845
1846 #if PREDICTIONS_VERBOSE
1847 _predicted_pending_cards = predict_pending_cards();
1848 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1849 if (full_young_gcs())
1850 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1851 else
1852 _predicted_cards_scanned +=
1853 predict_non_young_card_num(_predicted_rs_lengths);
1854 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1855
1856 _predicted_rs_update_time_ms =
1857 predict_rs_update_time_ms(_g1->pending_card_num());
1858 _predicted_rs_scan_time_ms =
1859 predict_rs_scan_time_ms(_predicted_cards_scanned);
1860 _predicted_object_copy_time_ms =
1861 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1862 _predicted_constant_other_time_ms =
1863 predict_constant_other_time_ms();
1864 _predicted_young_other_time_ms =
1865 predict_young_other_time_ms(_recorded_young_regions);
1866 _predicted_non_young_other_time_ms =
1867 predict_non_young_other_time_ms(_recorded_non_young_regions);
1868
1869 _predicted_pause_time_ms =
1870 _predicted_rs_update_time_ms +
1871 _predicted_rs_scan_time_ms +
1872 _predicted_object_copy_time_ms +
1873 _predicted_constant_other_time_ms +
1874 _predicted_young_other_time_ms +
1875 _predicted_non_young_other_time_ms;
1876 #endif // PREDICTIONS_VERBOSE
1877 }
1878
1879 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1880 predicted_time_ms) {
1881 // I don't think we need to do this when in young GC mode since
1882 // marking will be initiated next time we hit the soft limit anyway...
1883 if (predicted_time_ms > _expensive_region_limit_ms) {
1884 // no point in doing another partial one
1885 _should_revert_to_full_young_gcs = true;
1886 }
1887 }
1888
1889 // </NEW PREDICTION>
1890
1891
1892 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1893 double elapsed_ms) {
1894 _recent_gc_times_ms->add(elapsed_ms);
1895 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1896 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1897 }
1898
1899 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1900 if (_recent_pause_times_ms->num() == 0) {
1901 return (double) MaxGCPauseMillis;
1902 }
1903 return _recent_pause_times_ms->avg();
1904 }
1905
1906 double G1CollectorPolicy::recent_avg_time_for_rs_scan_ms() {
1907 if (_recent_rs_scan_times_ms->num() == 0) {
1908 return (double)MaxGCPauseMillis/3.0;
1909 }
1910 return _recent_rs_scan_times_ms->avg();
1911 }
1912
1913 int G1CollectorPolicy::number_of_recent_gcs() {
1914 assert(_recent_rs_scan_times_ms->num() ==
1915 _recent_pause_times_ms->num(), "Sequence out of sync");
1916 assert(_recent_pause_times_ms->num() ==
1917 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1918 assert(_recent_CS_bytes_used_before->num() ==
1919 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1920
1921 return _recent_pause_times_ms->num();
1922 }
1923
1924 double G1CollectorPolicy::recent_avg_survival_fraction() {
1925 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1926 _recent_CS_bytes_used_before);
1927 }
1928
1929 double G1CollectorPolicy::last_survival_fraction() {
1930 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1931 _recent_CS_bytes_used_before);
1932 }
1933
1934 double
1935 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1936 TruncatedSeq* before) {
1937 assert(surviving->num() == before->num(), "Sequence out of sync");
1938 if (before->sum() > 0.0) {
1939 double recent_survival_rate = surviving->sum() / before->sum();
1940 // We exempt parallel collection from this check because Alloc Buffer
1941 // fragmentation can produce negative collections.
1942 // Further, we're now always doing parallel collection. But I'm still
1943 // leaving this here as a placeholder for a more precise assertion later.
1944 // (DLD, 10/05.)
1945 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1946 _g1->evacuation_failed() ||
1947 recent_survival_rate <= 1.0, "Or bad frac");
1948 return recent_survival_rate;
1949 } else {
1950 return 1.0; // Be conservative.
1951 }
1952 }
1953
1954 double
1955 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
1956 TruncatedSeq* before) {
1957 assert(surviving->num() == before->num(), "Sequence out of sync");
1958 if (surviving->num() > 0 && before->last() > 0.0) {
1959 double last_survival_rate = surviving->last() / before->last();
1960 // We exempt parallel collection from this check because Alloc Buffer
1961 // fragmentation can produce negative collections.
1962 // Further, we're now always doing parallel collection. But I'm still
1963 // leaving this here as a placeholder for a more precise assertion later.
1964 // (DLD, 10/05.)
1965 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1966 last_survival_rate <= 1.0, "Or bad frac");
1967 return last_survival_rate;
1968 } else {
1969 return 1.0;
1970 }
1971 }
1972
1973 static const int survival_min_obs = 5;
1974 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
1975 static const double min_survival_rate = 0.1;
1976
1977 double
1978 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
1979 double latest) {
1980 double res = avg;
1981 if (number_of_recent_gcs() < survival_min_obs) {
1982 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
1983 }
1984 res = MAX2(res, latest);
1985 res = MAX2(res, min_survival_rate);
1986 // In the parallel case, LAB fragmentation can produce "negative
1987 // collections"; so can evac failure. Cap at 1.0
1988 res = MIN2(res, 1.0);
1989 return res;
1990 }
1991
1992 size_t G1CollectorPolicy::expansion_amount() {
1993 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
1994 // We will double the existing space, or take
1995 // G1ExpandByPercentOfAvailable % of the available expansion
1996 // space, whichever is smaller, bounded below by a minimum
1997 // expansion (unless that's all that's left.)
1998 const size_t min_expand_bytes = 1*M;
1999 size_t reserved_bytes = _g1->max_capacity();
2000 size_t committed_bytes = _g1->capacity();
2001 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2002 size_t expand_bytes;
2003 size_t expand_bytes_via_pct =
2004 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2005 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2006 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2007 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2008 if (G1PolicyVerbose > 1) {
2009 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2010 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2011 " Answer = %d.\n",
2012 recent_avg_pause_time_ratio(),
2013 byte_size_in_proper_unit(committed_bytes),
2014 proper_unit_for_byte_size(committed_bytes),
2015 byte_size_in_proper_unit(uncommitted_bytes),
2016 proper_unit_for_byte_size(uncommitted_bytes),
2017 byte_size_in_proper_unit(expand_bytes_via_pct),
2018 proper_unit_for_byte_size(expand_bytes_via_pct),
2019 byte_size_in_proper_unit(expand_bytes),
2020 proper_unit_for_byte_size(expand_bytes));
2021 }
2022 return expand_bytes;
2023 } else {
2024 return 0;
2025 }
2026 }
2027
2028 void G1CollectorPolicy::note_start_of_mark_thread() {
2029 _mark_thread_startup_sec = os::elapsedTime();
2030 }
2031
2032 class CountCSClosure: public HeapRegionClosure {
2033 G1CollectorPolicy* _g1_policy;
2034 public:
2035 CountCSClosure(G1CollectorPolicy* g1_policy) :
2036 _g1_policy(g1_policy) {}
2037 bool doHeapRegion(HeapRegion* r) {
2038 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2039 return false;
2040 }
2041 };
2042
2043 void G1CollectorPolicy::count_CS_bytes_used() {
2044 CountCSClosure cs_closure(this);
2045 _g1->collection_set_iterate(&cs_closure);
2046 }
2047
2048 void G1CollectorPolicy::print_summary (int level,
2049 const char* str,
2050 NumberSeq* seq) const {
2051 double sum = seq->sum();
2052 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2053 str, sum / 1000.0, seq->avg());
2054 }
2055
2056 void G1CollectorPolicy::print_summary_sd (int level,
2057 const char* str,
2058 NumberSeq* seq) const {
2059 print_summary(level, str, seq);
2060 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2061 seq->num(), seq->sd(), seq->maximum());
2062 }
2063
2064 void G1CollectorPolicy::check_other_times(int level,
2065 NumberSeq* other_times_ms,
2066 NumberSeq* calc_other_times_ms) const {
2067 bool should_print = false;
2068 LineBuffer buf(level + 2);
2069
2070 double max_sum = MAX2(fabs(other_times_ms->sum()),
2071 fabs(calc_other_times_ms->sum()));
2072 double min_sum = MIN2(fabs(other_times_ms->sum()),
2073 fabs(calc_other_times_ms->sum()));
2074 double sum_ratio = max_sum / min_sum;
2075 if (sum_ratio > 1.1) {
2076 should_print = true;
2077 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2078 }
2079
2080 double max_avg = MAX2(fabs(other_times_ms->avg()),
2081 fabs(calc_other_times_ms->avg()));
2082 double min_avg = MIN2(fabs(other_times_ms->avg()),
2083 fabs(calc_other_times_ms->avg()));
2084 double avg_ratio = max_avg / min_avg;
2085 if (avg_ratio > 1.1) {
2086 should_print = true;
2087 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2088 }
2089
2090 if (other_times_ms->sum() < -0.01) {
2091 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2092 }
2093
2094 if (other_times_ms->avg() < -0.01) {
2095 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2096 }
2097
2098 if (calc_other_times_ms->sum() < -0.01) {
2099 should_print = true;
2100 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2101 }
2102
2103 if (calc_other_times_ms->avg() < -0.01) {
2104 should_print = true;
2105 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2106 }
2107
2108 if (should_print)
2109 print_summary(level, "Other(Calc)", calc_other_times_ms);
2110 }
2111
2112 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2113 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
2114 MainBodySummary* body_summary = summary->main_body_summary();
2115 if (summary->get_total_seq()->num() > 0) {
2116 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2117 if (body_summary != NULL) {
2118 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2119 if (parallel) {
2120 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2121 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2122 print_summary(2, "Ext Root Scanning",
2123 body_summary->get_ext_root_scan_seq());
2124 print_summary(2, "Mark Stack Scanning",
2125 body_summary->get_mark_stack_scan_seq());
2126 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2127 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2128 print_summary(2, "Termination", body_summary->get_termination_seq());
2129 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2130 {
2131 NumberSeq* other_parts[] = {
2132 body_summary->get_update_rs_seq(),
2133 body_summary->get_ext_root_scan_seq(),
2134 body_summary->get_mark_stack_scan_seq(),
2135 body_summary->get_scan_rs_seq(),
2136 body_summary->get_obj_copy_seq(),
2137 body_summary->get_termination_seq()
2138 };
2139 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2140 6, other_parts);
2141 check_other_times(2, body_summary->get_parallel_other_seq(),
2142 &calc_other_times_ms);
2143 }
2144 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2145 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2146 } else {
2147 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2148 print_summary(1, "Ext Root Scanning",
2149 body_summary->get_ext_root_scan_seq());
2150 print_summary(1, "Mark Stack Scanning",
2151 body_summary->get_mark_stack_scan_seq());
2152 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2153 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2154 }
2155 }
2156 print_summary(1, "Other", summary->get_other_seq());
2157 {
2158 if (body_summary != NULL) {
2159 NumberSeq calc_other_times_ms;
2160 if (parallel) {
2161 // parallel
2162 NumberSeq* other_parts[] = {
2163 body_summary->get_satb_drain_seq(),
2164 body_summary->get_parallel_seq(),
2165 body_summary->get_clear_ct_seq()
2166 };
2167 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2168 3, other_parts);
2169 } else {
2170 // serial
2171 NumberSeq* other_parts[] = {
2172 body_summary->get_satb_drain_seq(),
2173 body_summary->get_update_rs_seq(),
2174 body_summary->get_ext_root_scan_seq(),
2175 body_summary->get_mark_stack_scan_seq(),
2176 body_summary->get_scan_rs_seq(),
2177 body_summary->get_obj_copy_seq()
2178 };
2179 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2180 6, other_parts);
2181 }
2182 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2183 }
2184 }
2185 } else {
2186 LineBuffer(1).append_and_print_cr("none");
2187 }
2188 LineBuffer(0).append_and_print_cr("");
2189 }
2190
2191 void G1CollectorPolicy::print_tracing_info() const {
2192 if (TraceGen0Time) {
2193 gclog_or_tty->print_cr("ALL PAUSES");
2194 print_summary_sd(0, "Total", _all_pause_times_ms);
2195 gclog_or_tty->print_cr("");
2196 gclog_or_tty->print_cr("");
2197 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2198 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2199 gclog_or_tty->print_cr("");
2200
2201 gclog_or_tty->print_cr("EVACUATION PAUSES");
2202 print_summary(_summary);
2203
2204 gclog_or_tty->print_cr("MISC");
2205 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2206 print_summary_sd(0, "Yields", _all_yield_times_ms);
2207 for (int i = 0; i < _aux_num; ++i) {
2208 if (_all_aux_times_ms[i].num() > 0) {
2209 char buffer[96];
2210 sprintf(buffer, "Aux%d", i);
2211 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2212 }
2213 }
2214
2215 size_t all_region_num = _region_num_young + _region_num_tenured;
2216 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2217 "Tenured %8d (%6.2lf%%)",
2218 all_region_num,
2219 _region_num_young,
2220 (double) _region_num_young / (double) all_region_num * 100.0,
2221 _region_num_tenured,
2222 (double) _region_num_tenured / (double) all_region_num * 100.0);
2223 }
2224 if (TraceGen1Time) {
2225 if (_all_full_gc_times_ms->num() > 0) {
2226 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2227 _all_full_gc_times_ms->num(),
2228 _all_full_gc_times_ms->sum() / 1000.0);
2229 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2230 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2231 _all_full_gc_times_ms->sd(),
2232 _all_full_gc_times_ms->maximum());
2233 }
2234 }
2235 }
2236
2237 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2238 #ifndef PRODUCT
2239 _short_lived_surv_rate_group->print_surv_rate_summary();
2240 // add this call for any other surv rate groups
2241 #endif // PRODUCT
2242 }
2243
2244 void
2245 G1CollectorPolicy::update_region_num(bool young) {
2246 if (young) {
2247 ++_region_num_young;
2248 } else {
2249 ++_region_num_tenured;
2250 }
2251 }
2252
2253 #ifndef PRODUCT
2254 // for debugging, bit of a hack...
2255 static char*
2256 region_num_to_mbs(int length) {
2257 static char buffer[64];
2258 double bytes = (double) (length * HeapRegion::GrainBytes);
2259 double mbs = bytes / (double) (1024 * 1024);
2260 sprintf(buffer, "%7.2lfMB", mbs);
2261 return buffer;
2262 }
2263 #endif // PRODUCT
2264
2265 size_t G1CollectorPolicy::max_regions(int purpose) {
2266 switch (purpose) {
2267 case GCAllocForSurvived:
2268 return _max_survivor_regions;
2269 case GCAllocForTenured:
2270 return REGIONS_UNLIMITED;
2271 default:
2272 ShouldNotReachHere();
2273 return REGIONS_UNLIMITED;
2274 };
2275 }
2276
2277 void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
2278 size_t expansion_region_num = 0;
2279 if (GCLockerEdenExpansionPercent > 0) {
2280 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2281 double expansion_region_num_d = perc * (double) _young_list_target_length;
2282 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2283 // less than 1.0) we'll get 1.
2284 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2285 } else {
2286 assert(expansion_region_num == 0, "sanity");
2287 }
2288 _young_list_max_length = _young_list_target_length + expansion_region_num;
2289 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2290 }
2291
2292 // Calculates survivor space parameters.
2293 void G1CollectorPolicy::calculate_survivors_policy()
2294 {
2295 if (G1FixedSurvivorSpaceSize == 0) {
2296 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2297 } else {
2298 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2299 }
2300
2301 if (G1FixedTenuringThreshold) {
2302 _tenuring_threshold = MaxTenuringThreshold;
2303 } else {
2304 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2305 HeapRegion::GrainWords * _max_survivor_regions);
2306 }
2307 }
2308
2309 #ifndef PRODUCT
2310 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2311 CollectionSetChooser* _chooser;
2312 public:
2313 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2314 _chooser(chooser) {}
2315
2316 bool doHeapRegion(HeapRegion* r) {
2317 if (!r->continuesHumongous()) {
2318 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2319 }
2320 return false;
2321 }
2322 };
2323
2324 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2325 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2326 _g1->heap_region_iterate(&cl);
2327 return true;
2328 }
2329 #endif
2330
2331 bool
2332 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2333 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2334 if (!during_cycle) {
2335 set_initiate_conc_mark_if_possible();
2336 return true;
2337 } else {
2338 return false;
2339 }
2340 }
2341
2342 void
2343 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2344 // We are about to decide on whether this pause will be an
2345 // initial-mark pause.
2346
2347 // First, during_initial_mark_pause() should not be already set. We
2348 // will set it here if we have to. However, it should be cleared by
2349 // the end of the pause (it's only set for the duration of an
2350 // initial-mark pause).
2351 assert(!during_initial_mark_pause(), "pre-condition");
2352
2353 if (initiate_conc_mark_if_possible()) {
2354 // We had noticed on a previous pause that the heap occupancy has
2355 // gone over the initiating threshold and we should start a
2356 // concurrent marking cycle. So we might initiate one.
2357
2358 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2359 if (!during_cycle) {
2360 // The concurrent marking thread is not "during a cycle", i.e.,
2361 // it has completed the last one. So we can go ahead and
2362 // initiate a new cycle.
2363
2364 set_during_initial_mark_pause();
2365
2366 // And we can now clear initiate_conc_mark_if_possible() as
2367 // we've already acted on it.
2368 clear_initiate_conc_mark_if_possible();
2369 } else {
2370 // The concurrent marking thread is still finishing up the
2371 // previous cycle. If we start one right now the two cycles
2372 // overlap. In particular, the concurrent marking thread might
2373 // be in the process of clearing the next marking bitmap (which
2374 // we will use for the next cycle if we start one). Starting a
2375 // cycle now will be bad given that parts of the marking
2376 // information might get cleared by the marking thread. And we
2377 // cannot wait for the marking thread to finish the cycle as it
2378 // periodically yields while clearing the next marking bitmap
2379 // and, if it's in a yield point, it's waiting for us to
2380 // finish. So, at this point we will not start a cycle and we'll
2381 // let the concurrent marking thread complete the last one.
2382 }
2383 }
2384 }
2385
2386 void
2387 G1CollectorPolicy_BestRegionsFirst::
2388 record_collection_pause_start(double start_time_sec, size_t start_used) {
2389 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2390 }
2391
2392 class KnownGarbageClosure: public HeapRegionClosure {
2393 CollectionSetChooser* _hrSorted;
2394
2395 public:
2396 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2397 _hrSorted(hrSorted)
2398 {}
2399
2400 bool doHeapRegion(HeapRegion* r) {
2401 // We only include humongous regions in collection
2402 // sets when concurrent mark shows that their contained object is
2403 // unreachable.
2404
2405 // Do we have any marking information for this region?
2406 if (r->is_marked()) {
2407 // We don't include humongous regions in collection
2408 // sets because we collect them immediately at the end of a marking
2409 // cycle. We also don't include young regions because we *must*
2410 // include them in the next collection pause.
2411 if (!r->isHumongous() && !r->is_young()) {
2412 _hrSorted->addMarkedHeapRegion(r);
2413 }
2414 }
2415 return false;
2416 }
2417 };
2418
2419 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2420 CollectionSetChooser* _hrSorted;
2421 jint _marked_regions_added;
2422 jint _chunk_size;
2423 jint _cur_chunk_idx;
2424 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2425 int _worker;
2426 int _invokes;
2427
2428 void get_new_chunk() {
2429 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2430 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2431 }
2432 void add_region(HeapRegion* r) {
2433 if (_cur_chunk_idx == _cur_chunk_end) {
2434 get_new_chunk();
2435 }
2436 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2437 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2438 _marked_regions_added++;
2439 _cur_chunk_idx++;
2440 }
2441
2442 public:
2443 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2444 jint chunk_size,
2445 int worker) :
2446 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2447 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2448 _invokes(0)
2449 {}
2450
2451 bool doHeapRegion(HeapRegion* r) {
2452 // We only include humongous regions in collection
2453 // sets when concurrent mark shows that their contained object is
2454 // unreachable.
2455 _invokes++;
2456
2457 // Do we have any marking information for this region?
2458 if (r->is_marked()) {
2459 // We don't include humongous regions in collection
2460 // sets because we collect them immediately at the end of a marking
2461 // cycle.
2462 // We also do not include young regions in collection sets
2463 if (!r->isHumongous() && !r->is_young()) {
2464 add_region(r);
2465 }
2466 }
2467 return false;
2468 }
2469 jint marked_regions_added() { return _marked_regions_added; }
2470 int invokes() { return _invokes; }
2471 };
2472
2473 class ParKnownGarbageTask: public AbstractGangTask {
2474 CollectionSetChooser* _hrSorted;
2475 jint _chunk_size;
2476 G1CollectedHeap* _g1;
2477 public:
2478 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2479 AbstractGangTask("ParKnownGarbageTask"),
2480 _hrSorted(hrSorted), _chunk_size(chunk_size),
2481 _g1(G1CollectedHeap::heap())
2482 {}
2483
2484 void work(int i) {
2485 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2486 // Back to zero for the claim value.
2487 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2488 HeapRegion::InitialClaimValue);
2489 jint regions_added = parKnownGarbageCl.marked_regions_added();
2490 _hrSorted->incNumMarkedHeapRegions(regions_added);
2491 if (G1PrintParCleanupStats) {
2492 gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
2493 i, parKnownGarbageCl.invokes(), regions_added);
2494 }
2495 }
2496 };
2497
2498 void
2499 G1CollectorPolicy_BestRegionsFirst::
2500 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2501 size_t max_live_bytes) {
2502 double start;
2503 if (G1PrintParCleanupStats) start = os::elapsedTime();
2504 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2505
2506 _collectionSetChooser->clearMarkedHeapRegions();
2507 double clear_marked_end;
2508 if (G1PrintParCleanupStats) {
2509 clear_marked_end = os::elapsedTime();
2510 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2511 (clear_marked_end - start)*1000.0);
2512 }
2513 if (G1CollectedHeap::use_parallel_gc_threads()) {
2514 const size_t OverpartitionFactor = 4;
2515 const size_t MinWorkUnit = 8;
2516 const size_t WorkUnit =
2517 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2518 MinWorkUnit);
2519 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2520 WorkUnit);
2521 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2522 (int) WorkUnit);
2523 _g1->workers()->run_task(&parKnownGarbageTask);
2524
2525 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2526 "sanity check");
2527 } else {
2528 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2529 _g1->heap_region_iterate(&knownGarbagecl);
2530 }
2531 double known_garbage_end;
2532 if (G1PrintParCleanupStats) {
2533 known_garbage_end = os::elapsedTime();
2534 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2535 (known_garbage_end - clear_marked_end)*1000.0);
2536 }
2537 _collectionSetChooser->sortMarkedHeapRegions();
2538 double sort_end;
2539 if (G1PrintParCleanupStats) {
2540 sort_end = os::elapsedTime();
2541 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2542 (sort_end - known_garbage_end)*1000.0);
2543 }
2544
2545 record_concurrent_mark_cleanup_end_work2();
2546 double work2_end;
2547 if (G1PrintParCleanupStats) {
2548 work2_end = os::elapsedTime();
2549 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2550 (work2_end - sort_end)*1000.0);
2551 }
2552 }
2553
2554 // Add the heap region at the head of the non-incremental collection set
2555 void G1CollectorPolicy::
2556 add_to_collection_set(HeapRegion* hr) {
2557 assert(_inc_cset_build_state == Active, "Precondition");
2558 assert(!hr->is_young(), "non-incremental add of young region");
2559
2560 if (_g1->mark_in_progress())
2561 _g1->concurrent_mark()->registerCSetRegion(hr);
2562
2563 assert(!hr->in_collection_set(), "should not already be in the CSet");
2564 hr->set_in_collection_set(true);
2565 hr->set_next_in_collection_set(_collection_set);
2566 _collection_set = hr;
2567 _collection_set_size++;
2568 _collection_set_bytes_used_before += hr->used();
2569 _g1->register_region_with_in_cset_fast_test(hr);
2570 }
2571
2572 // Initialize the per-collection-set information
2573 void G1CollectorPolicy::start_incremental_cset_building() {
2574 assert(_inc_cset_build_state == Inactive, "Precondition");
2575
2576 _inc_cset_head = NULL;
2577 _inc_cset_tail = NULL;
2578 _inc_cset_size = 0;
2579 _inc_cset_bytes_used_before = 0;
2580
2581 _inc_cset_young_index = 0;
2582
2583 _inc_cset_max_finger = 0;
2584 _inc_cset_recorded_young_bytes = 0;
2585 _inc_cset_recorded_rs_lengths = 0;
2586 _inc_cset_predicted_elapsed_time_ms = 0;
2587 _inc_cset_predicted_bytes_to_copy = 0;
2588 _inc_cset_build_state = Active;
2589 }
2590
2591 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2592 // This routine is used when:
2593 // * adding survivor regions to the incremental cset at the end of an
2594 // evacuation pause,
2595 // * adding the current allocation region to the incremental cset
2596 // when it is retired, and
2597 // * updating existing policy information for a region in the
2598 // incremental cset via young list RSet sampling.
2599 // Therefore this routine may be called at a safepoint by the
2600 // VM thread, or in-between safepoints by mutator threads (when
2601 // retiring the current allocation region) or a concurrent
2602 // refine thread (RSet sampling).
2603
2604 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2605 size_t used_bytes = hr->used();
2606
2607 _inc_cset_recorded_rs_lengths += rs_length;
2608 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2609
2610 _inc_cset_bytes_used_before += used_bytes;
2611
2612 // Cache the values we have added to the aggregated informtion
2613 // in the heap region in case we have to remove this region from
2614 // the incremental collection set, or it is updated by the
2615 // rset sampling code
2616 hr->set_recorded_rs_length(rs_length);
2617 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2618
2619 #if PREDICTIONS_VERBOSE
2620 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2621 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2622
2623 // Record the number of bytes used in this region
2624 _inc_cset_recorded_young_bytes += used_bytes;
2625
2626 // Cache the values we have added to the aggregated informtion
2627 // in the heap region in case we have to remove this region from
2628 // the incremental collection set, or it is updated by the
2629 // rset sampling code
2630 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2631 #endif // PREDICTIONS_VERBOSE
2632 }
2633
2634 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2635 // This routine is currently only called as part of the updating of
2636 // existing policy information for regions in the incremental cset that
2637 // is performed by the concurrent refine thread(s) as part of young list
2638 // RSet sampling. Therefore we should not be at a safepoint.
2639
2640 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2641 assert(hr->is_young(), "it should be");
2642
2643 size_t used_bytes = hr->used();
2644 size_t old_rs_length = hr->recorded_rs_length();
2645 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2646
2647 // Subtract the old recorded/predicted policy information for
2648 // the given heap region from the collection set info.
2649 _inc_cset_recorded_rs_lengths -= old_rs_length;
2650 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2651
2652 _inc_cset_bytes_used_before -= used_bytes;
2653
2654 // Clear the values cached in the heap region
2655 hr->set_recorded_rs_length(0);
2656 hr->set_predicted_elapsed_time_ms(0);
2657
2658 #if PREDICTIONS_VERBOSE
2659 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2660 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2661
2662 // Subtract the number of bytes used in this region
2663 _inc_cset_recorded_young_bytes -= used_bytes;
2664
2665 // Clear the values cached in the heap region
2666 hr->set_predicted_bytes_to_copy(0);
2667 #endif // PREDICTIONS_VERBOSE
2668 }
2669
2670 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2671 // Update the collection set information that is dependent on the new RS length
2672 assert(hr->is_young(), "Precondition");
2673
2674 remove_from_incremental_cset_info(hr);
2675 add_to_incremental_cset_info(hr, new_rs_length);
2676 }
2677
2678 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2679 assert( hr->is_young(), "invariant");
2680 assert( hr->young_index_in_cset() == -1, "invariant" );
2681 assert(_inc_cset_build_state == Active, "Precondition");
2682
2683 // We need to clear and set the cached recorded/cached collection set
2684 // information in the heap region here (before the region gets added
2685 // to the collection set). An individual heap region's cached values
2686 // are calculated, aggregated with the policy collection set info,
2687 // and cached in the heap region here (initially) and (subsequently)
2688 // by the Young List sampling code.
2689
2690 size_t rs_length = hr->rem_set()->occupied();
2691 add_to_incremental_cset_info(hr, rs_length);
2692
2693 HeapWord* hr_end = hr->end();
2694 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2695
2696 assert(!hr->in_collection_set(), "invariant");
2697 hr->set_in_collection_set(true);
2698 assert( hr->next_in_collection_set() == NULL, "invariant");
2699
2700 _inc_cset_size++;
2701 _g1->register_region_with_in_cset_fast_test(hr);
2702
2703 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2704 ++_inc_cset_young_index;
2705 }
2706
2707 // Add the region at the RHS of the incremental cset
2708 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2709 // We should only ever be appending survivors at the end of a pause
2710 assert( hr->is_survivor(), "Logic");
2711
2712 // Do the 'common' stuff
2713 add_region_to_incremental_cset_common(hr);
2714
2715 // Now add the region at the right hand side
2716 if (_inc_cset_tail == NULL) {
2717 assert(_inc_cset_head == NULL, "invariant");
2718 _inc_cset_head = hr;
2719 } else {
2720 _inc_cset_tail->set_next_in_collection_set(hr);
2721 }
2722 _inc_cset_tail = hr;
2723 }
2724
2725 // Add the region to the LHS of the incremental cset
2726 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2727 // Survivors should be added to the RHS at the end of a pause
2728 assert(!hr->is_survivor(), "Logic");
2729
2730 // Do the 'common' stuff
2731 add_region_to_incremental_cset_common(hr);
2732
2733 // Add the region at the left hand side
2734 hr->set_next_in_collection_set(_inc_cset_head);
2735 if (_inc_cset_head == NULL) {
2736 assert(_inc_cset_tail == NULL, "Invariant");
2737 _inc_cset_tail = hr;
2738 }
2739 _inc_cset_head = hr;
2740 }
2741
2742 #ifndef PRODUCT
2743 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2744 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2745
2746 st->print_cr("\nCollection_set:");
2747 HeapRegion* csr = list_head;
2748 while (csr != NULL) {
2749 HeapRegion* next = csr->next_in_collection_set();
2750 assert(csr->in_collection_set(), "bad CS");
2751 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2752 "age: %4d, y: %d, surv: %d",
2753 csr->bottom(), csr->end(),
2754 csr->top(),
2755 csr->prev_top_at_mark_start(),
2756 csr->next_top_at_mark_start(),
2757 csr->top_at_conc_mark_count(),
2758 csr->age_in_surv_rate_group_cond(),
2759 csr->is_young(),
2760 csr->is_survivor());
2761 csr = next;
2762 }
2763 }
2764 #endif // !PRODUCT
2765
2766 void
2767 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2768 double target_pause_time_ms) {
2769 // Set this here - in case we're not doing young collections.
2770 double non_young_start_time_sec = os::elapsedTime();
2771
2772 start_recording_regions();
2773
2774 guarantee(target_pause_time_ms > 0.0,
2775 err_msg("target_pause_time_ms = %1.6lf should be positive",
2776 target_pause_time_ms));
2777 guarantee(_collection_set == NULL, "Precondition");
2778
2779 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2780 double predicted_pause_time_ms = base_time_ms;
2781
2782 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2783
2784 // the 10% and 50% values are arbitrary...
2785 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2786 time_remaining_ms = 0.50 * target_pause_time_ms;
2787 _within_target = false;
2788 } else {
2789 _within_target = true;
2790 }
2791
2792 // We figure out the number of bytes available for future to-space.
2793 // For new regions without marking information, we must assume the
2794 // worst-case of complete survival. If we have marking information for a
2795 // region, we can bound the amount of live data. We can add a number of
2796 // such regions, as long as the sum of the live data bounds does not
2797 // exceed the available evacuation space.
2798 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2799
2800 size_t expansion_bytes =
2801 _g1->expansion_regions() * HeapRegion::GrainBytes;
2802
2803 _collection_set_bytes_used_before = 0;
2804 _collection_set_size = 0;
2805
2806 // Adjust for expansion and slop.
2807 max_live_bytes = max_live_bytes + expansion_bytes;
2808
2809 HeapRegion* hr;
2810 double young_start_time_sec = os::elapsedTime();
2811
2812 if (G1PolicyVerbose > 0) {
2813 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2814 _g1->young_list()->length());
2815 }
2816
2817 _young_cset_length = 0;
2818 _last_young_gc_full = full_young_gcs() ? true : false;
2819
2820 if (_last_young_gc_full)
2821 ++_full_young_pause_num;
2822 else
2823 ++_partial_young_pause_num;
2824
2825 // The young list is laid with the survivor regions from the previous
2826 // pause are appended to the RHS of the young list, i.e.
2827 // [Newly Young Regions ++ Survivors from last pause].
2828
2829 hr = _g1->young_list()->first_survivor_region();
2830 while (hr != NULL) {
2831 assert(hr->is_survivor(), "badly formed young list");
2832 hr->set_young();
2833 hr = hr->get_next_young_region();
2834 }
2835
2836 // Clear the fields that point to the survivor list - they are
2837 // all young now.
2838 _g1->young_list()->clear_survivors();
2839
2840 if (_g1->mark_in_progress())
2841 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2842
2843 _young_cset_length = _inc_cset_young_index;
2844 _collection_set = _inc_cset_head;
2845 _collection_set_size = _inc_cset_size;
2846 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2847
2848 // For young regions in the collection set, we assume the worst
2849 // case of complete survival
2850 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2851
2852 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2853 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2854
2855 // The number of recorded young regions is the incremental
2856 // collection set's current size
2857 set_recorded_young_regions(_inc_cset_size);
2858 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2859 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2860 #if PREDICTIONS_VERBOSE
2861 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2862 #endif // PREDICTIONS_VERBOSE
2863
2864 if (G1PolicyVerbose > 0) {
2865 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2866 _inc_cset_size);
2867 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2868 max_live_bytes/K);
2869 }
2870
2871 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2872
2873 double young_end_time_sec = os::elapsedTime();
2874 _recorded_young_cset_choice_time_ms =
2875 (young_end_time_sec - young_start_time_sec) * 1000.0;
2876
2877 // We are doing young collections so reset this.
2878 non_young_start_time_sec = young_end_time_sec;
2879
2880 // Note we can use either _collection_set_size or
2881 // _young_cset_length here
2882 if (_collection_set_size > 0 && _last_young_gc_full) {
2883 // don't bother adding more regions...
2884 goto choose_collection_set_end;
2885 }
2886
2887 if (!full_young_gcs()) {
2888 bool should_continue = true;
2889 NumberSeq seq;
2890 double avg_prediction = 100000000000000000.0; // something very large
2891
2892 do {
2893 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2894 avg_prediction);
2895 if (hr != NULL) {
2896 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2897 time_remaining_ms -= predicted_time_ms;
2898 predicted_pause_time_ms += predicted_time_ms;
2899 add_to_collection_set(hr);
2900 record_non_young_cset_region(hr);
2901 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2902 if (G1PolicyVerbose > 0) {
2903 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2904 max_live_bytes/K);
2905 }
2906 seq.add(predicted_time_ms);
2907 avg_prediction = seq.avg() + seq.sd();
2908 }
2909 should_continue =
2910 ( hr != NULL) &&
2911 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
2912 : _collection_set_size < _young_list_fixed_length );
2913 } while (should_continue);
2914
2915 if (!adaptive_young_list_length() &&
2916 _collection_set_size < _young_list_fixed_length)
2917 _should_revert_to_full_young_gcs = true;
2918 }
2919
2920 choose_collection_set_end:
2921 stop_incremental_cset_building();
2922
2923 count_CS_bytes_used();
2924
2925 end_recording_regions();
2926
2927 double non_young_end_time_sec = os::elapsedTime();
2928 _recorded_non_young_cset_choice_time_ms =
2929 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2930 }
2931
2932 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
2933 G1CollectorPolicy::record_full_collection_end();
2934 _collectionSetChooser->updateAfterFullCollection();
2935 }
2936
2937 void G1CollectorPolicy_BestRegionsFirst::
2938 expand_if_possible(size_t numRegions) {
2939 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
2940 _g1->expand(expansion_bytes);
2941 }
2942
2943 void G1CollectorPolicy_BestRegionsFirst::
2944 record_collection_pause_end() {
2945 G1CollectorPolicy::record_collection_pause_end();
2946 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
2947 }