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 _in_young_gc_mode(false),
205 _full_young_gcs(true),
206 _full_young_pause_num(0),
207 _partial_young_pause_num(0),
208
209 _during_marking(false),
210 _in_marking_window(false),
211 _in_marking_window_im(false),
212
213 _known_garbage_ratio(0.0),
214 _known_garbage_bytes(0),
215
216 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
217
218 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
219
220 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
221 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
222
223 _recent_avg_pause_time_ratio(0.0),
224 _num_markings(0),
225 _n_marks(0),
226 _n_pauses_at_mark_end(0),
227
228 _all_full_gc_times_ms(new NumberSeq()),
229
230 // G1PausesBtwnConcMark defaults to -1
231 // so the hack is to do the cast QQQ FIXME
232 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
233 _n_marks_since_last_pause(0),
234 _initiate_conc_mark_if_possible(false),
235 _during_initial_mark_pause(false),
236 _should_revert_to_full_young_gcs(false),
237 _last_full_young_gc(false),
238
239 _eden_bytes_before_gc(0),
240 _survivor_bytes_before_gc(0),
241 _capacity_before_gc(0),
242
243 _prev_collection_pause_used_at_end_bytes(0),
244
245 _collection_set(NULL),
246 _collection_set_size(0),
247 _collection_set_bytes_used_before(0),
248
249 // Incremental CSet attributes
250 _inc_cset_build_state(Inactive),
251 _inc_cset_head(NULL),
252 _inc_cset_tail(NULL),
253 _inc_cset_size(0),
254 _inc_cset_young_index(0),
255 _inc_cset_bytes_used_before(0),
256 _inc_cset_max_finger(NULL),
257 _inc_cset_recorded_young_bytes(0),
258 _inc_cset_recorded_rs_lengths(0),
259 _inc_cset_predicted_elapsed_time_ms(0.0),
260 _inc_cset_predicted_bytes_to_copy(0),
261
262 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
263 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
264 #endif // _MSC_VER
265
266 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
267 G1YoungSurvRateNumRegionsSummary)),
268 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
269 G1YoungSurvRateNumRegionsSummary)),
270 // add here any more surv rate groups
271 _recorded_survivor_regions(0),
272 _recorded_survivor_head(NULL),
273 _recorded_survivor_tail(NULL),
274 _survivors_age_table(true),
275
276 _gc_overhead_perc(0.0)
277
278 {
279 // Set up the region size and associated fields. Given that the
280 // policy is created before the heap, we have to set this up here,
281 // so it's done as soon as possible.
282 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
283 HeapRegionRemSet::setup_remset_size();
284
285 // Verify PLAB sizes
286 const uint region_size = HeapRegion::GrainWords;
287 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
288 char buffer[128];
289 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
290 OldPLABSize > region_size ? "Old" : "Young", region_size);
291 vm_exit_during_initialization(buffer);
292 }
293
294 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
295 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
296
297 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
298 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
299 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
300
301 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
302 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
303
304 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
305
306 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
307
308 _par_last_termination_times_ms = new double[_parallel_gc_threads];
309 _par_last_termination_attempts = new double[_parallel_gc_threads];
310 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
311 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
312
313 // start conservatively
314 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
315
316 // <NEW PREDICTION>
317
318 int index;
319 if (ParallelGCThreads == 0)
320 index = 0;
321 else if (ParallelGCThreads > 8)
322 index = 7;
323 else
324 index = ParallelGCThreads - 1;
325
326 _pending_card_diff_seq->add(0.0);
327 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
328 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
329 _fully_young_cards_per_entry_ratio_seq->add(
330 fully_young_cards_per_entry_ratio_defaults[index]);
331 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
332 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
333 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
334 _young_other_cost_per_region_ms_seq->add(
335 young_other_cost_per_region_ms_defaults[index]);
336 _non_young_other_cost_per_region_ms_seq->add(
337 non_young_other_cost_per_region_ms_defaults[index]);
338
339 // </NEW PREDICTION>
340
341 // Below, we might need to calculate the pause time target based on
342 // the pause interval. When we do so we are going to give G1 maximum
343 // flexibility and allow it to do pauses when it needs to. So, we'll
344 // arrange that the pause interval to be pause time target + 1 to
345 // ensure that a) the pause time target is maximized with respect to
346 // the pause interval and b) we maintain the invariant that pause
347 // time target < pause interval. If the user does not want this
348 // maximum flexibility, they will have to set the pause interval
349 // explicitly.
350
351 // First make sure that, if either parameter is set, its value is
352 // reasonable.
353 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
354 if (MaxGCPauseMillis < 1) {
355 vm_exit_during_initialization("MaxGCPauseMillis should be "
356 "greater than 0");
357 }
358 }
359 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
360 if (GCPauseIntervalMillis < 1) {
361 vm_exit_during_initialization("GCPauseIntervalMillis should be "
362 "greater than 0");
363 }
364 }
365
366 // Then, if the pause time target parameter was not set, set it to
367 // the default value.
368 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
369 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
370 // The default pause time target in G1 is 200ms
371 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
372 } else {
373 // We do not allow the pause interval to be set without the
374 // pause time target
375 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
376 "without setting MaxGCPauseMillis");
377 }
378 }
379
380 // Then, if the interval parameter was not set, set it according to
381 // the pause time target (this will also deal with the case when the
382 // pause time target is the default value).
383 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
384 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
385 }
386
387 // Finally, make sure that the two parameters are consistent.
388 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
389 char buffer[256];
390 jio_snprintf(buffer, 256,
391 "MaxGCPauseMillis (%u) should be less than "
392 "GCPauseIntervalMillis (%u)",
393 MaxGCPauseMillis, GCPauseIntervalMillis);
394 vm_exit_during_initialization(buffer);
395 }
396
397 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
398 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
399 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
400 _sigma = (double) G1ConfidencePercent / 100.0;
401
402 // start conservatively (around 50ms is about right)
403 _concurrent_mark_init_times_ms->add(0.05);
404 _concurrent_mark_remark_times_ms->add(0.05);
405 _concurrent_mark_cleanup_times_ms->add(0.20);
406 _tenuring_threshold = MaxTenuringThreshold;
407
408 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
409 // fixed, then _max_survivor_regions will be calculated at
410 // calculate_young_list_target_length during initialization
411 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
412
413 assert(GCTimeRatio > 0,
414 "we should have set it to a default value set_g1_gc_flags() "
415 "if a user set it to 0");
416 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
417
418 initialize_all();
419 }
420
421 // Increment "i", mod "len"
422 static void inc_mod(int& i, int len) {
423 i++; if (i == len) i = 0;
424 }
425
426 void G1CollectorPolicy::initialize_flags() {
427 set_min_alignment(HeapRegion::GrainBytes);
428 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
429 if (SurvivorRatio < 1) {
430 vm_exit_during_initialization("Invalid survivor ratio specified");
431 }
432 CollectorPolicy::initialize_flags();
433 }
434
435 // The easiest way to deal with the parsing of the NewSize /
436 // MaxNewSize / etc. parameteres is to re-use the code in the
437 // TwoGenerationCollectorPolicy class. This is similar to what
438 // ParallelScavenge does with its GenerationSizer class (see
439 // ParallelScavengeHeap::initialize()). We might change this in the
440 // future, but it's a good start.
441 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
442 size_t size_to_region_num(size_t byte_size) {
443 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
444 }
445
446 public:
447 G1YoungGenSizer() {
448 initialize_flags();
449 initialize_size_info();
450 }
451
452 size_t min_young_region_num() {
453 return size_to_region_num(_min_gen0_size);
454 }
455 size_t initial_young_region_num() {
456 return size_to_region_num(_initial_gen0_size);
457 }
458 size_t max_young_region_num() {
459 return size_to_region_num(_max_gen0_size);
460 }
461 };
462
463 void G1CollectorPolicy::init() {
464 // Set aside an initial future to_space.
465 _g1 = G1CollectedHeap::heap();
466
467 assert(Heap_lock->owned_by_self(), "Locking discipline.");
468
469 initialize_gc_policy_counters();
470
471 if (G1Gen) {
472 _in_young_gc_mode = true;
473
474 G1YoungGenSizer sizer;
475 size_t initial_region_num = sizer.initial_young_region_num();
476
477 if (UseAdaptiveSizePolicy) {
478 set_adaptive_young_list_length(true);
479 _young_list_fixed_length = 0;
480 } else {
481 set_adaptive_young_list_length(false);
482 _young_list_fixed_length = initial_region_num;
483 }
484 _free_regions_at_end_of_collection = _g1->free_regions();
485 calculate_young_list_min_length();
486 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
487 calculate_young_list_target_length();
488 } else {
489 _young_list_fixed_length = 0;
490 _in_young_gc_mode = false;
491 }
492
493 // We may immediately start allocating regions and placing them on the
494 // collection set list. Initialize the per-collection set info
495 start_incremental_cset_building();
496 }
497
498 // Create the jstat counters for the policy.
499 void G1CollectorPolicy::initialize_gc_policy_counters()
500 {
501 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
502 }
503
504 void G1CollectorPolicy::calculate_young_list_min_length() {
505 _young_list_min_length = 0;
506
507 if (!adaptive_young_list_length())
508 return;
509
510 if (_alloc_rate_ms_seq->num() > 3) {
511 double now_sec = os::elapsedTime();
512 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
513 double alloc_rate_ms = predict_alloc_rate_ms();
514 size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
515 size_t current_region_num = _g1->young_list()->length();
516 _young_list_min_length = min_regions + current_region_num;
517 }
518 }
519
520 void G1CollectorPolicy::calculate_young_list_target_length() {
521 if (adaptive_young_list_length()) {
522 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
523 calculate_young_list_target_length(rs_lengths);
524 } else {
525 if (full_young_gcs())
526 _young_list_target_length = _young_list_fixed_length;
527 else
528 _young_list_target_length = _young_list_fixed_length / 2;
529 }
530
531 // Make sure we allow the application to allocate at least one
532 // region before we need to do a collection again.
533 size_t min_length = _g1->young_list()->length() + 1;
534 _young_list_target_length = MAX2(_young_list_target_length, min_length);
535 calculate_max_gc_locker_expansion();
536 calculate_survivors_policy();
537 }
538
539 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
540 guarantee( adaptive_young_list_length(), "pre-condition" );
541 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
542
543 double start_time_sec = os::elapsedTime();
544 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
545 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
546 size_t reserve_regions =
547 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
548
549 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
550 // we are in fully-young mode and there are free regions in the heap
551
552 double survivor_regions_evac_time =
553 predict_survivor_regions_evac_time();
554
555 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
556 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
557 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
558 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
559 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
560 + survivor_regions_evac_time;
561
562 // the result
563 size_t final_young_length = 0;
564
565 size_t init_free_regions =
566 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
567
568 // if we're still under the pause target...
569 if (base_time_ms <= target_pause_time_ms) {
570 // We make sure that the shortest young length that makes sense
571 // fits within the target pause time.
572 size_t min_young_length = 1;
573
574 if (predict_will_fit(min_young_length, base_time_ms,
575 init_free_regions, target_pause_time_ms)) {
576 // The shortest young length will fit within the target pause time;
577 // we'll now check whether the absolute maximum number of young
578 // regions will fit in the target pause time. If not, we'll do
579 // a binary search between min_young_length and max_young_length
580 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
581 size_t max_young_length = abs_max_young_length;
582
583 if (max_young_length > min_young_length) {
584 // Let's check if the initial max young length will fit within the
585 // target pause. If so then there is no need to search for a maximal
586 // young length - we'll return the initial maximum
587
588 if (predict_will_fit(max_young_length, base_time_ms,
589 init_free_regions, target_pause_time_ms)) {
590 // The maximum young length will satisfy the target pause time.
591 // We are done so set min young length to this maximum length.
592 // The code after the loop will then set final_young_length using
593 // the value cached in the minimum length.
594 min_young_length = max_young_length;
595 } else {
596 // The maximum possible number of young regions will not fit within
597 // the target pause time so let's search....
598
599 size_t diff = (max_young_length - min_young_length) / 2;
600 max_young_length = min_young_length + diff;
601
602 while (max_young_length > min_young_length) {
603 if (predict_will_fit(max_young_length, base_time_ms,
604 init_free_regions, target_pause_time_ms)) {
605
606 // The current max young length will fit within the target
607 // pause time. Note we do not exit the loop here. By setting
608 // min = max, and then increasing the max below means that
609 // we will continue searching for an upper bound in the
610 // range [max..max+diff]
611 min_young_length = max_young_length;
612 }
613 diff = (max_young_length - min_young_length) / 2;
614 max_young_length = min_young_length + diff;
615 }
616 // the above loop found a maximal young length that will fit
617 // within the target pause time.
618 }
619 assert(min_young_length <= abs_max_young_length, "just checking");
620 }
621 final_young_length = min_young_length;
622 }
623 }
624 // and we're done!
625
626 // we should have at least one region in the target young length
627 _young_list_target_length =
628 final_young_length + _recorded_survivor_regions;
629
630 // let's keep an eye of how long we spend on this calculation
631 // right now, I assume that we'll print it when we need it; we
632 // should really adde it to the breakdown of a pause
633 double end_time_sec = os::elapsedTime();
634 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
635
636 #ifdef TRACE_CALC_YOUNG_LENGTH
637 // leave this in for debugging, just in case
638 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
639 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
640 target_pause_time_ms,
641 _young_list_target_length
642 elapsed_time_ms,
643 full_young_gcs() ? "full" : "partial",
644 during_initial_mark_pause() ? " i-m" : "",
645 _in_marking_window,
646 _in_marking_window_im);
647 #endif // TRACE_CALC_YOUNG_LENGTH
648
649 if (_young_list_target_length < _young_list_min_length) {
650 // bummer; this means that, if we do a pause when the maximal
651 // length dictates, we'll violate the pause spacing target (the
652 // min length was calculate based on the application's current
653 // alloc rate);
654
655 // so, we have to bite the bullet, and allocate the minimum
656 // number. We'll violate our target, but we just can't meet it.
657
658 #ifdef TRACE_CALC_YOUNG_LENGTH
659 // leave this in for debugging, just in case
660 gclog_or_tty->print_cr("adjusted target length from "
661 SIZE_FORMAT " to " SIZE_FORMAT,
662 _young_list_target_length, _young_list_min_length);
663 #endif // TRACE_CALC_YOUNG_LENGTH
664
665 _young_list_target_length = _young_list_min_length;
666 }
667 } else {
668 // we are in a partially-young mode or we've run out of regions (due
669 // to evacuation failure)
670
671 #ifdef TRACE_CALC_YOUNG_LENGTH
672 // leave this in for debugging, just in case
673 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
674 _young_list_min_length);
675 #endif // TRACE_CALC_YOUNG_LENGTH
676 // we'll do the pause as soon as possible by choosing the minimum
677 _young_list_target_length = _young_list_min_length;
678 }
679
680 _rs_lengths_prediction = rs_lengths;
681 }
682
683 // This is used by: calculate_young_list_target_length(rs_length). It
684 // returns true iff:
685 // the predicted pause time for the given young list will not overflow
686 // the target pause time
687 // and:
688 // the predicted amount of surviving data will not overflow the
689 // the amount of free space available for survivor regions.
690 //
691 bool
692 G1CollectorPolicy::predict_will_fit(size_t young_length,
693 double base_time_ms,
694 size_t init_free_regions,
695 double target_pause_time_ms) {
696
697 if (young_length >= init_free_regions)
698 // end condition 1: not enough space for the young regions
699 return false;
700
701 double accum_surv_rate_adj = 0.0;
702 double accum_surv_rate =
703 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
704
705 size_t bytes_to_copy =
706 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
707
708 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
709
710 double young_other_time_ms =
711 predict_young_other_time_ms(young_length);
712
713 double pause_time_ms =
714 base_time_ms + copy_time_ms + young_other_time_ms;
715
716 if (pause_time_ms > target_pause_time_ms)
717 // end condition 2: over the target pause time
718 return false;
719
720 size_t free_bytes =
721 (init_free_regions - young_length) * HeapRegion::GrainBytes;
722
723 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
724 // end condition 3: out of to-space (conservatively)
725 return false;
726
727 // success!
728 return true;
729 }
730
731 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
732 double survivor_regions_evac_time = 0.0;
733 for (HeapRegion * r = _recorded_survivor_head;
734 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
735 r = r->get_next_young_region()) {
736 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
737 }
738 return survivor_regions_evac_time;
739 }
740
741 void G1CollectorPolicy::check_prediction_validity() {
742 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
743
744 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
745 if (rs_lengths > _rs_lengths_prediction) {
746 // add 10% to avoid having to recalculate often
747 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
748 calculate_young_list_target_length(rs_lengths_prediction);
749 }
750 }
751
752 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
753 bool is_tlab,
754 bool* gc_overhead_limit_was_exceeded) {
755 guarantee(false, "Not using this policy feature yet.");
756 return NULL;
757 }
758
759 // This method controls how a collector handles one or more
760 // of its generations being fully allocated.
761 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
762 bool is_tlab) {
763 guarantee(false, "Not using this policy feature yet.");
764 return NULL;
765 }
766
767
768 #ifndef PRODUCT
769 bool G1CollectorPolicy::verify_young_ages() {
770 HeapRegion* head = _g1->young_list()->first_region();
771 return
772 verify_young_ages(head, _short_lived_surv_rate_group);
773 // also call verify_young_ages on any additional surv rate groups
774 }
775
776 bool
777 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
778 SurvRateGroup *surv_rate_group) {
779 guarantee( surv_rate_group != NULL, "pre-condition" );
780
781 const char* name = surv_rate_group->name();
782 bool ret = true;
783 int prev_age = -1;
784
785 for (HeapRegion* curr = head;
786 curr != NULL;
787 curr = curr->get_next_young_region()) {
788 SurvRateGroup* group = curr->surv_rate_group();
789 if (group == NULL && !curr->is_survivor()) {
790 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
791 ret = false;
792 }
793
794 if (surv_rate_group == group) {
795 int age = curr->age_in_surv_rate_group();
796
797 if (age < 0) {
798 gclog_or_tty->print_cr("## %s: encountered negative age", name);
799 ret = false;
800 }
801
802 if (age <= prev_age) {
803 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
804 "(%d, %d)", name, age, prev_age);
805 ret = false;
806 }
807 prev_age = age;
808 }
809 }
810
811 return ret;
812 }
813 #endif // PRODUCT
814
815 void G1CollectorPolicy::record_full_collection_start() {
816 _cur_collection_start_sec = os::elapsedTime();
817 // Release the future to-space so that it is available for compaction into.
818 _g1->set_full_collection();
819 }
820
821 void G1CollectorPolicy::record_full_collection_end() {
822 // Consider this like a collection pause for the purposes of allocation
823 // since last pause.
824 double end_sec = os::elapsedTime();
825 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
826 double full_gc_time_ms = full_gc_time_sec * 1000.0;
827
828 _all_full_gc_times_ms->add(full_gc_time_ms);
829
830 update_recent_gc_times(end_sec, full_gc_time_ms);
831
832 _g1->clear_full_collection();
833
834 // "Nuke" the heuristics that control the fully/partially young GC
835 // transitions and make sure we start with fully young GCs after the
836 // Full GC.
837 set_full_young_gcs(true);
838 _last_full_young_gc = false;
839 _should_revert_to_full_young_gcs = false;
840 clear_initiate_conc_mark_if_possible();
841 clear_during_initial_mark_pause();
842 _known_garbage_bytes = 0;
843 _known_garbage_ratio = 0.0;
844 _in_marking_window = false;
845 _in_marking_window_im = false;
846
847 _short_lived_surv_rate_group->start_adding_regions();
848 // also call this on any additional surv rate groups
849
850 record_survivor_regions(0, NULL, NULL);
851
852 _prev_region_num_young = _region_num_young;
853 _prev_region_num_tenured = _region_num_tenured;
854
855 _free_regions_at_end_of_collection = _g1->free_regions();
856 // Reset survivors SurvRateGroup.
857 _survivor_surv_rate_group->reset();
858 calculate_young_list_min_length();
859 calculate_young_list_target_length();
860 }
861
862 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
863 _bytes_in_to_space_before_gc += bytes;
864 }
865
866 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
867 _bytes_in_to_space_after_gc += bytes;
868 }
869
870 void G1CollectorPolicy::record_stop_world_start() {
871 _stop_world_start = os::elapsedTime();
872 }
873
874 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
875 size_t start_used) {
876 if (PrintGCDetails) {
877 gclog_or_tty->stamp(PrintGCTimeStamps);
878 gclog_or_tty->print("[GC pause");
879 if (in_young_gc_mode())
880 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
881 }
882
883 assert(_g1->used() == _g1->recalculate_used(),
884 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
885 _g1->used(), _g1->recalculate_used()));
886
887 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
888 _all_stop_world_times_ms->add(s_w_t_ms);
889 _stop_world_start = 0.0;
890
891 _cur_collection_start_sec = start_time_sec;
892 _cur_collection_pause_used_at_start_bytes = start_used;
893 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
894 _pending_cards = _g1->pending_card_num();
895 _max_pending_cards = _g1->max_pending_card_num();
896
897 _bytes_in_to_space_before_gc = 0;
898 _bytes_in_to_space_after_gc = 0;
899 _bytes_in_collection_set_before_gc = 0;
900
901 YoungList* young_list = _g1->young_list();
902 _eden_bytes_before_gc = young_list->eden_used_bytes();
903 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
904 _capacity_before_gc = _g1->capacity();
905
906 #ifdef DEBUG
907 // initialise these to something well known so that we can spot
908 // if they are not set properly
909
910 for (int i = 0; i < _parallel_gc_threads; ++i) {
911 _par_last_gc_worker_start_times_ms[i] = -1234.0;
912 _par_last_ext_root_scan_times_ms[i] = -1234.0;
913 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
914 _par_last_update_rs_times_ms[i] = -1234.0;
915 _par_last_update_rs_processed_buffers[i] = -1234.0;
916 _par_last_scan_rs_times_ms[i] = -1234.0;
917 _par_last_obj_copy_times_ms[i] = -1234.0;
918 _par_last_termination_times_ms[i] = -1234.0;
919 _par_last_termination_attempts[i] = -1234.0;
920 _par_last_gc_worker_end_times_ms[i] = -1234.0;
921 _par_last_gc_worker_times_ms[i] = -1234.0;
922 }
923 #endif
924
925 for (int i = 0; i < _aux_num; ++i) {
926 _cur_aux_times_ms[i] = 0.0;
927 _cur_aux_times_set[i] = false;
928 }
929
930 _satb_drain_time_set = false;
931 _last_satb_drain_processed_buffers = -1;
932
933 if (in_young_gc_mode())
934 _last_young_gc_full = false;
935
936 // do that for any other surv rate groups
937 _short_lived_surv_rate_group->stop_adding_regions();
938 _survivors_age_table.clear();
939
940 assert( verify_young_ages(), "region age verification" );
941 }
942
943 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
944 _mark_closure_time_ms = mark_closure_time_ms;
945 }
946
947 void G1CollectorPolicy::record_concurrent_mark_init_start() {
948 _mark_init_start_sec = os::elapsedTime();
949 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
950 }
951
952 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
953 mark_init_elapsed_time_ms) {
954 _during_marking = true;
955 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
956 clear_during_initial_mark_pause();
957 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
958 }
959
960 void G1CollectorPolicy::record_concurrent_mark_init_end() {
961 double end_time_sec = os::elapsedTime();
962 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
963 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
964 record_concurrent_mark_init_end_pre(elapsed_time_ms);
965
966 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
967 }
968
969 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
970 _mark_remark_start_sec = os::elapsedTime();
971 _during_marking = false;
972 }
973
974 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
975 double end_time_sec = os::elapsedTime();
976 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
977 _concurrent_mark_remark_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_remark_start_sec, end_time_sec, true);
982 }
983
984 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
985 _mark_cleanup_start_sec = os::elapsedTime();
986 }
987
988 void
989 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
990 size_t max_live_bytes) {
991 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
992 record_concurrent_mark_cleanup_end_work2();
993 }
994
995 void
996 G1CollectorPolicy::
997 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
998 size_t max_live_bytes) {
999 if (_n_marks < 2) _n_marks++;
1000 if (G1PolicyVerbose > 0)
1001 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
1002 " (of " SIZE_FORMAT " MB heap).",
1003 max_live_bytes/M, _g1->capacity()/M);
1004 }
1005
1006 // The important thing about this is that it includes "os::elapsedTime".
1007 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
1008 double end_time_sec = os::elapsedTime();
1009 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
1010 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1011 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1012 _prev_collection_pause_end_ms += elapsed_time_ms;
1013
1014 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
1015
1016 _num_markings++;
1017
1018 // We did a marking, so reset the "since_last_mark" variables.
1019 double considerConcMarkCost = 1.0;
1020 // If there are available processors, concurrent activity is free...
1021 if (Threads::number_of_non_daemon_threads() * 2 <
1022 os::active_processor_count()) {
1023 considerConcMarkCost = 0.0;
1024 }
1025 _n_pauses_at_mark_end = _n_pauses;
1026 _n_marks_since_last_pause++;
1027 }
1028
1029 void
1030 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
1031 if (in_young_gc_mode()) {
1032 _should_revert_to_full_young_gcs = false;
1033 _last_full_young_gc = true;
1034 _in_marking_window = false;
1035 if (adaptive_young_list_length())
1036 calculate_young_list_target_length();
1037 }
1038 }
1039
1040 void G1CollectorPolicy::record_concurrent_pause() {
1041 if (_stop_world_start > 0.0) {
1042 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
1043 _all_yield_times_ms->add(yield_ms);
1044 }
1045 }
1046
1047 void G1CollectorPolicy::record_concurrent_pause_end() {
1048 }
1049
1050 template<class T>
1051 T sum_of(T* sum_arr, int start, int n, int N) {
1052 T sum = (T)0;
1053 for (int i = 0; i < n; i++) {
1054 int j = (start + i) % N;
1055 sum += sum_arr[j];
1056 }
1057 return sum;
1058 }
1059
1060 void G1CollectorPolicy::print_par_stats(int level,
1061 const char* str,
1062 double* data) {
1063 double min = data[0], max = data[0];
1064 double total = 0.0;
1065 LineBuffer buf(level);
1066 buf.append("[%s (ms):", str);
1067 for (uint i = 0; i < ParallelGCThreads; ++i) {
1068 double val = data[i];
1069 if (val < min)
1070 min = val;
1071 if (val > max)
1072 max = val;
1073 total += val;
1074 buf.append(" %3.1lf", val);
1075 }
1076 buf.append_and_print_cr("");
1077 double avg = total / (double) ParallelGCThreads;
1078 buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
1079 avg, min, max, max - min);
1080 }
1081
1082 void G1CollectorPolicy::print_par_sizes(int level,
1083 const char* str,
1084 double* data) {
1085 double min = data[0], max = data[0];
1086 double total = 0.0;
1087 LineBuffer buf(level);
1088 buf.append("[%s :", str);
1089 for (uint i = 0; i < ParallelGCThreads; ++i) {
1090 double val = data[i];
1091 if (val < min)
1092 min = val;
1093 if (val > max)
1094 max = val;
1095 total += val;
1096 buf.append(" %d", (int) val);
1097 }
1098 buf.append_and_print_cr("");
1099 double avg = total / (double) ParallelGCThreads;
1100 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1101 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1102 }
1103
1104 void G1CollectorPolicy::print_stats (int level,
1105 const char* str,
1106 double value) {
1107 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1108 }
1109
1110 void G1CollectorPolicy::print_stats (int level,
1111 const char* str,
1112 int value) {
1113 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1114 }
1115
1116 double G1CollectorPolicy::avg_value (double* data) {
1117 if (G1CollectedHeap::use_parallel_gc_threads()) {
1118 double ret = 0.0;
1119 for (uint i = 0; i < ParallelGCThreads; ++i)
1120 ret += data[i];
1121 return ret / (double) ParallelGCThreads;
1122 } else {
1123 return data[0];
1124 }
1125 }
1126
1127 double G1CollectorPolicy::max_value (double* data) {
1128 if (G1CollectedHeap::use_parallel_gc_threads()) {
1129 double ret = data[0];
1130 for (uint i = 1; i < ParallelGCThreads; ++i)
1131 if (data[i] > ret)
1132 ret = data[i];
1133 return ret;
1134 } else {
1135 return data[0];
1136 }
1137 }
1138
1139 double G1CollectorPolicy::sum_of_values (double* data) {
1140 if (G1CollectedHeap::use_parallel_gc_threads()) {
1141 double sum = 0.0;
1142 for (uint i = 0; i < ParallelGCThreads; i++)
1143 sum += data[i];
1144 return sum;
1145 } else {
1146 return data[0];
1147 }
1148 }
1149
1150 double G1CollectorPolicy::max_sum (double* data1,
1151 double* data2) {
1152 double ret = data1[0] + data2[0];
1153
1154 if (G1CollectedHeap::use_parallel_gc_threads()) {
1155 for (uint i = 1; i < ParallelGCThreads; ++i) {
1156 double data = data1[i] + data2[i];
1157 if (data > ret)
1158 ret = data;
1159 }
1160 }
1161 return ret;
1162 }
1163
1164 // Anything below that is considered to be zero
1165 #define MIN_TIMER_GRANULARITY 0.0000001
1166
1167 void G1CollectorPolicy::record_collection_pause_end() {
1168 double end_time_sec = os::elapsedTime();
1169 double elapsed_ms = _last_pause_time_ms;
1170 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1171 size_t rs_size =
1172 _cur_collection_pause_used_regions_at_start - collection_set_size();
1173 size_t cur_used_bytes = _g1->used();
1174 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1175 bool last_pause_included_initial_mark = false;
1176 bool update_stats = !_g1->evacuation_failed();
1177
1178 #ifndef PRODUCT
1179 if (G1YoungSurvRateVerbose) {
1180 gclog_or_tty->print_cr("");
1181 _short_lived_surv_rate_group->print();
1182 // do that for any other surv rate groups too
1183 }
1184 #endif // PRODUCT
1185
1186 if (in_young_gc_mode()) {
1187 last_pause_included_initial_mark = during_initial_mark_pause();
1188 if (last_pause_included_initial_mark)
1189 record_concurrent_mark_init_end_pre(0.0);
1190
1191 size_t min_used_targ =
1192 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1193
1194
1195 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1196 assert(!last_pause_included_initial_mark, "invariant");
1197 if (cur_used_bytes > min_used_targ &&
1198 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1199 assert(!during_initial_mark_pause(), "we should not see this here");
1200
1201 // Note: this might have already been set, if during the last
1202 // pause we decided to start a cycle but at the beginning of
1203 // this pause we decided to postpone it. That's OK.
1204 set_initiate_conc_mark_if_possible();
1205 }
1206 }
1207
1208 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1209 }
1210
1211 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1212 end_time_sec, false);
1213
1214 guarantee(_cur_collection_pause_used_regions_at_start >=
1215 collection_set_size(),
1216 "Negative RS size?");
1217
1218 // This assert is exempted when we're doing parallel collection pauses,
1219 // because the fragmentation caused by the parallel GC allocation buffers
1220 // can lead to more memory being used during collection than was used
1221 // before. Best leave this out until the fragmentation problem is fixed.
1222 // Pauses in which evacuation failed can also lead to negative
1223 // collections, since no space is reclaimed from a region containing an
1224 // object whose evacuation failed.
1225 // Further, we're now always doing parallel collection. But I'm still
1226 // leaving this here as a placeholder for a more precise assertion later.
1227 // (DLD, 10/05.)
1228 assert((true || parallel) // Always using GC LABs now.
1229 || _g1->evacuation_failed()
1230 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1231 "Negative collection");
1232
1233 size_t freed_bytes =
1234 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1235 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1236
1237 double survival_fraction =
1238 (double)surviving_bytes/
1239 (double)_collection_set_bytes_used_before;
1240
1241 _n_pauses++;
1242
1243 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1244 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1245 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1246 double update_rs_processed_buffers =
1247 sum_of_values(_par_last_update_rs_processed_buffers);
1248 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1249 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1250 double termination_time = avg_value(_par_last_termination_times_ms);
1251
1252 double parallel_known_time = update_rs_time +
1253 ext_root_scan_time +
1254 mark_stack_scan_time +
1255 scan_rs_time +
1256 obj_copy_time +
1257 termination_time;
1258
1259 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1260
1261 PauseSummary* summary = _summary;
1262
1263 if (update_stats) {
1264 _recent_rs_scan_times_ms->add(scan_rs_time);
1265 _recent_pause_times_ms->add(elapsed_ms);
1266 _recent_rs_sizes->add(rs_size);
1267
1268 MainBodySummary* body_summary = summary->main_body_summary();
1269 guarantee(body_summary != NULL, "should not be null!");
1270
1271 if (_satb_drain_time_set)
1272 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1273 else
1274 body_summary->record_satb_drain_time_ms(0.0);
1275
1276 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1277 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1278 body_summary->record_update_rs_time_ms(update_rs_time);
1279 body_summary->record_scan_rs_time_ms(scan_rs_time);
1280 body_summary->record_obj_copy_time_ms(obj_copy_time);
1281 if (parallel) {
1282 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1283 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1284 body_summary->record_termination_time_ms(termination_time);
1285 body_summary->record_parallel_other_time_ms(parallel_other_time);
1286 }
1287 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1288
1289 // We exempt parallel collection from this check because Alloc Buffer
1290 // fragmentation can produce negative collections. Same with evac
1291 // failure.
1292 // Further, we're now always doing parallel collection. But I'm still
1293 // leaving this here as a placeholder for a more precise assertion later.
1294 // (DLD, 10/05.
1295 assert((true || parallel)
1296 || _g1->evacuation_failed()
1297 || surviving_bytes <= _collection_set_bytes_used_before,
1298 "Or else negative collection!");
1299 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1300 _recent_CS_bytes_surviving->add(surviving_bytes);
1301
1302 // this is where we update the allocation rate of the application
1303 double app_time_ms =
1304 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1305 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1306 // This usually happens due to the timer not having the required
1307 // granularity. Some Linuxes are the usual culprits.
1308 // We'll just set it to something (arbitrarily) small.
1309 app_time_ms = 1.0;
1310 }
1311 size_t regions_allocated =
1312 (_region_num_young - _prev_region_num_young) +
1313 (_region_num_tenured - _prev_region_num_tenured);
1314 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1315 _alloc_rate_ms_seq->add(alloc_rate_ms);
1316 _prev_region_num_young = _region_num_young;
1317 _prev_region_num_tenured = _region_num_tenured;
1318
1319 double interval_ms =
1320 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1321 update_recent_gc_times(end_time_sec, elapsed_ms);
1322 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1323 if (recent_avg_pause_time_ratio() < 0.0 ||
1324 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1325 #ifndef PRODUCT
1326 // Dump info to allow post-facto debugging
1327 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1328 gclog_or_tty->print_cr("-------------------------------------------");
1329 gclog_or_tty->print_cr("Recent GC Times (ms):");
1330 _recent_gc_times_ms->dump();
1331 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1332 _recent_prev_end_times_for_all_gcs_sec->dump();
1333 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1334 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1335 // In debug mode, terminate the JVM if the user wants to debug at this point.
1336 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1337 #endif // !PRODUCT
1338 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1339 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1340 if (_recent_avg_pause_time_ratio < 0.0) {
1341 _recent_avg_pause_time_ratio = 0.0;
1342 } else {
1343 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1344 _recent_avg_pause_time_ratio = 1.0;
1345 }
1346 }
1347 }
1348
1349 if (G1PolicyVerbose > 1) {
1350 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1351 }
1352
1353 if (G1PolicyVerbose > 1) {
1354 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1355 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1356 " |RS|: " SIZE_FORMAT,
1357 elapsed_ms, recent_avg_time_for_pauses_ms(),
1358 scan_rs_time, recent_avg_time_for_rs_scan_ms(),
1359 rs_size);
1360
1361 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1362 " At end " SIZE_FORMAT "K\n"
1363 " garbage : " SIZE_FORMAT "K"
1364 " of " SIZE_FORMAT "K\n"
1365 " survival : %6.2f%% (%6.2f%% avg)",
1366 _cur_collection_pause_used_at_start_bytes/K,
1367 _g1->used()/K, freed_bytes/K,
1368 _collection_set_bytes_used_before/K,
1369 survival_fraction*100.0,
1370 recent_avg_survival_fraction()*100.0);
1371 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1372 recent_avg_pause_time_ratio() * 100.0);
1373 }
1374
1375 double other_time_ms = elapsed_ms;
1376
1377 if (_satb_drain_time_set) {
1378 other_time_ms -= _cur_satb_drain_time_ms;
1379 }
1380
1381 if (parallel) {
1382 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1383 } else {
1384 other_time_ms -=
1385 update_rs_time +
1386 ext_root_scan_time + mark_stack_scan_time +
1387 scan_rs_time + obj_copy_time;
1388 }
1389
1390 if (PrintGCDetails) {
1391 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1392 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1393 elapsed_ms / 1000.0);
1394
1395 if (_satb_drain_time_set) {
1396 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1397 }
1398 if (_last_satb_drain_processed_buffers >= 0) {
1399 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1400 }
1401 if (parallel) {
1402 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1403 print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
1404 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1405 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1406 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1407 print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
1408 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1409 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1410 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1411 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1412 print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);
1413
1414 for (int i = 0; i < _parallel_gc_threads; i++) {
1415 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
1416 }
1417 print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);
1418
1419 print_stats(2, "Parallel Other", parallel_other_time);
1420 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1421 } else {
1422 print_stats(1, "Update RS", update_rs_time);
1423 print_stats(2, "Processed Buffers",
1424 (int)update_rs_processed_buffers);
1425 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1426 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1427 print_stats(1, "Scan RS", scan_rs_time);
1428 print_stats(1, "Object Copying", obj_copy_time);
1429 }
1430 #ifndef PRODUCT
1431 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1432 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1433 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1434 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1435 if (_num_cc_clears > 0) {
1436 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1437 }
1438 #endif
1439 print_stats(1, "Other", other_time_ms);
1440 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1441
1442 for (int i = 0; i < _aux_num; ++i) {
1443 if (_cur_aux_times_set[i]) {
1444 char buffer[96];
1445 sprintf(buffer, "Aux%d", i);
1446 print_stats(1, buffer, _cur_aux_times_ms[i]);
1447 }
1448 }
1449 }
1450
1451 _all_pause_times_ms->add(elapsed_ms);
1452 if (update_stats) {
1453 summary->record_total_time_ms(elapsed_ms);
1454 summary->record_other_time_ms(other_time_ms);
1455 }
1456 for (int i = 0; i < _aux_num; ++i)
1457 if (_cur_aux_times_set[i])
1458 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1459
1460 // Reset marks-between-pauses counter.
1461 _n_marks_since_last_pause = 0;
1462
1463 // Update the efficiency-since-mark vars.
1464 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1465 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1466 // This usually happens due to the timer not having the required
1467 // granularity. Some Linuxes are the usual culprits.
1468 // We'll just set it to something (arbitrarily) small.
1469 proc_ms = 1.0;
1470 }
1471 double cur_efficiency = (double) freed_bytes / proc_ms;
1472
1473 bool new_in_marking_window = _in_marking_window;
1474 bool new_in_marking_window_im = false;
1475 if (during_initial_mark_pause()) {
1476 new_in_marking_window = true;
1477 new_in_marking_window_im = true;
1478 }
1479
1480 if (in_young_gc_mode()) {
1481 if (_last_full_young_gc) {
1482 set_full_young_gcs(false);
1483 _last_full_young_gc = false;
1484 }
1485
1486 if ( !_last_young_gc_full ) {
1487 if ( _should_revert_to_full_young_gcs ||
1488 _known_garbage_ratio < 0.05 ||
1489 (adaptive_young_list_length() &&
1490 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1491 set_full_young_gcs(true);
1492 }
1493 }
1494 _should_revert_to_full_young_gcs = false;
1495
1496 if (_last_young_gc_full && !_during_marking)
1497 _young_gc_eff_seq->add(cur_efficiency);
1498 }
1499
1500 _short_lived_surv_rate_group->start_adding_regions();
1501 // do that for any other surv rate groupsx
1502
1503 // <NEW PREDICTION>
1504
1505 if (update_stats) {
1506 double pause_time_ms = elapsed_ms;
1507
1508 size_t diff = 0;
1509 if (_max_pending_cards >= _pending_cards)
1510 diff = _max_pending_cards - _pending_cards;
1511 _pending_card_diff_seq->add((double) diff);
1512
1513 double cost_per_card_ms = 0.0;
1514 if (_pending_cards > 0) {
1515 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1516 _cost_per_card_ms_seq->add(cost_per_card_ms);
1517 }
1518
1519 size_t cards_scanned = _g1->cards_scanned();
1520
1521 double cost_per_entry_ms = 0.0;
1522 if (cards_scanned > 10) {
1523 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1524 if (_last_young_gc_full)
1525 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1526 else
1527 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1528 }
1529
1530 if (_max_rs_lengths > 0) {
1531 double cards_per_entry_ratio =
1532 (double) cards_scanned / (double) _max_rs_lengths;
1533 if (_last_young_gc_full)
1534 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1535 else
1536 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1537 }
1538
1539 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1540 if (rs_length_diff >= 0)
1541 _rs_length_diff_seq->add((double) rs_length_diff);
1542
1543 size_t copied_bytes = surviving_bytes;
1544 double cost_per_byte_ms = 0.0;
1545 if (copied_bytes > 0) {
1546 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1547 if (_in_marking_window)
1548 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1549 else
1550 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1551 }
1552
1553 double all_other_time_ms = pause_time_ms -
1554 (update_rs_time + scan_rs_time + obj_copy_time +
1555 _mark_closure_time_ms + termination_time);
1556
1557 double young_other_time_ms = 0.0;
1558 if (_recorded_young_regions > 0) {
1559 young_other_time_ms =
1560 _recorded_young_cset_choice_time_ms +
1561 _recorded_young_free_cset_time_ms;
1562 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1563 (double) _recorded_young_regions);
1564 }
1565 double non_young_other_time_ms = 0.0;
1566 if (_recorded_non_young_regions > 0) {
1567 non_young_other_time_ms =
1568 _recorded_non_young_cset_choice_time_ms +
1569 _recorded_non_young_free_cset_time_ms;
1570
1571 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1572 (double) _recorded_non_young_regions);
1573 }
1574
1575 double constant_other_time_ms = all_other_time_ms -
1576 (young_other_time_ms + non_young_other_time_ms);
1577 _constant_other_time_ms_seq->add(constant_other_time_ms);
1578
1579 double survival_ratio = 0.0;
1580 if (_bytes_in_collection_set_before_gc > 0) {
1581 survival_ratio = (double) bytes_in_to_space_during_gc() /
1582 (double) _bytes_in_collection_set_before_gc;
1583 }
1584
1585 _pending_cards_seq->add((double) _pending_cards);
1586 _scanned_cards_seq->add((double) cards_scanned);
1587 _rs_lengths_seq->add((double) _max_rs_lengths);
1588
1589 double expensive_region_limit_ms =
1590 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1591 if (expensive_region_limit_ms < 0.0) {
1592 // this means that the other time was predicted to be longer than
1593 // than the max pause time
1594 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1595 }
1596 _expensive_region_limit_ms = expensive_region_limit_ms;
1597
1598 if (PREDICTIONS_VERBOSE) {
1599 gclog_or_tty->print_cr("");
1600 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1601 "REGIONS %d %d %d "
1602 "PENDING_CARDS %d %d "
1603 "CARDS_SCANNED %d %d "
1604 "RS_LENGTHS %d %d "
1605 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1606 "SURVIVAL_RATIO %1.6lf %1.6lf "
1607 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1608 "OTHER_YOUNG %1.6lf %1.6lf "
1609 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1610 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1611 "ELAPSED %1.6lf %1.6lf ",
1612 _cur_collection_start_sec,
1613 (!_last_young_gc_full) ? 2 :
1614 (last_pause_included_initial_mark) ? 1 : 0,
1615 _recorded_region_num,
1616 _recorded_young_regions,
1617 _recorded_non_young_regions,
1618 _predicted_pending_cards, _pending_cards,
1619 _predicted_cards_scanned, cards_scanned,
1620 _predicted_rs_lengths, _max_rs_lengths,
1621 _predicted_rs_update_time_ms, update_rs_time,
1622 _predicted_rs_scan_time_ms, scan_rs_time,
1623 _predicted_survival_ratio, survival_ratio,
1624 _predicted_object_copy_time_ms, obj_copy_time,
1625 _predicted_constant_other_time_ms, constant_other_time_ms,
1626 _predicted_young_other_time_ms, young_other_time_ms,
1627 _predicted_non_young_other_time_ms,
1628 non_young_other_time_ms,
1629 _vtime_diff_ms, termination_time,
1630 _predicted_pause_time_ms, elapsed_ms);
1631 }
1632
1633 if (G1PolicyVerbose > 0) {
1634 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1635 _predicted_pause_time_ms,
1636 (_within_target) ? "within" : "outside",
1637 elapsed_ms);
1638 }
1639
1640 }
1641
1642 _in_marking_window = new_in_marking_window;
1643 _in_marking_window_im = new_in_marking_window_im;
1644 _free_regions_at_end_of_collection = _g1->free_regions();
1645 calculate_young_list_min_length();
1646 calculate_young_list_target_length();
1647
1648 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1649 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1650 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1651 // </NEW PREDICTION>
1652 }
1653
1654 #define EXT_SIZE_FORMAT "%d%s"
1655 #define EXT_SIZE_PARAMS(bytes) \
1656 byte_size_in_proper_unit((bytes)), \
1657 proper_unit_for_byte_size((bytes))
1658
1659 void G1CollectorPolicy::print_heap_transition() {
1660 if (PrintGCDetails) {
1661 YoungList* young_list = _g1->young_list();
1662 size_t eden_bytes = young_list->eden_used_bytes();
1663 size_t survivor_bytes = young_list->survivor_used_bytes();
1664 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1665 size_t used = _g1->used();
1666 size_t capacity = _g1->capacity();
1667
1668 gclog_or_tty->print_cr(
1669 " [Eden: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1670 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1671 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1672 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1673 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1674 EXT_SIZE_PARAMS(eden_bytes),
1675 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1676 EXT_SIZE_PARAMS(survivor_bytes),
1677 EXT_SIZE_PARAMS(used_before_gc),
1678 EXT_SIZE_PARAMS(_capacity_before_gc),
1679 EXT_SIZE_PARAMS(used),
1680 EXT_SIZE_PARAMS(capacity));
1681 } else if (PrintGC) {
1682 _g1->print_size_transition(gclog_or_tty,
1683 _cur_collection_pause_used_at_start_bytes,
1684 _g1->used(), _g1->capacity());
1685 }
1686 }
1687
1688 // <NEW PREDICTION>
1689
1690 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1691 double update_rs_processed_buffers,
1692 double goal_ms) {
1693 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1694 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1695
1696 if (G1UseAdaptiveConcRefinement) {
1697 const int k_gy = 3, k_gr = 6;
1698 const double inc_k = 1.1, dec_k = 0.9;
1699
1700 int g = cg1r->green_zone();
1701 if (update_rs_time > goal_ms) {
1702 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1703 } else {
1704 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1705 g = (int)MAX2(g * inc_k, g + 1.0);
1706 }
1707 }
1708 // Change the refinement threads params
1709 cg1r->set_green_zone(g);
1710 cg1r->set_yellow_zone(g * k_gy);
1711 cg1r->set_red_zone(g * k_gr);
1712 cg1r->reinitialize_threads();
1713
1714 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1715 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1716 cg1r->yellow_zone());
1717 // Change the barrier params
1718 dcqs.set_process_completed_threshold(processing_threshold);
1719 dcqs.set_max_completed_queue(cg1r->red_zone());
1720 }
1721
1722 int curr_queue_size = dcqs.completed_buffers_num();
1723 if (curr_queue_size >= cg1r->yellow_zone()) {
1724 dcqs.set_completed_queue_padding(curr_queue_size);
1725 } else {
1726 dcqs.set_completed_queue_padding(0);
1727 }
1728 dcqs.notify_if_necessary();
1729 }
1730
1731 double
1732 G1CollectorPolicy::
1733 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1734 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1735
1736 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1737 size_t young_num = g1h->young_list()->length();
1738 if (young_num == 0)
1739 return 0.0;
1740
1741 young_num += adjustment;
1742 size_t pending_cards = predict_pending_cards();
1743 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1744 predict_rs_length_diff();
1745 size_t card_num;
1746 if (full_young_gcs())
1747 card_num = predict_young_card_num(rs_lengths);
1748 else
1749 card_num = predict_non_young_card_num(rs_lengths);
1750 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1751 double accum_yg_surv_rate =
1752 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1753
1754 size_t bytes_to_copy =
1755 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1756
1757 return
1758 predict_rs_update_time_ms(pending_cards) +
1759 predict_rs_scan_time_ms(card_num) +
1760 predict_object_copy_time_ms(bytes_to_copy) +
1761 predict_young_other_time_ms(young_num) +
1762 predict_constant_other_time_ms();
1763 }
1764
1765 double
1766 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1767 size_t rs_length = predict_rs_length_diff();
1768 size_t card_num;
1769 if (full_young_gcs())
1770 card_num = predict_young_card_num(rs_length);
1771 else
1772 card_num = predict_non_young_card_num(rs_length);
1773 return predict_base_elapsed_time_ms(pending_cards, card_num);
1774 }
1775
1776 double
1777 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1778 size_t scanned_cards) {
1779 return
1780 predict_rs_update_time_ms(pending_cards) +
1781 predict_rs_scan_time_ms(scanned_cards) +
1782 predict_constant_other_time_ms();
1783 }
1784
1785 double
1786 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1787 bool young) {
1788 size_t rs_length = hr->rem_set()->occupied();
1789 size_t card_num;
1790 if (full_young_gcs())
1791 card_num = predict_young_card_num(rs_length);
1792 else
1793 card_num = predict_non_young_card_num(rs_length);
1794 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1795
1796 double region_elapsed_time_ms =
1797 predict_rs_scan_time_ms(card_num) +
1798 predict_object_copy_time_ms(bytes_to_copy);
1799
1800 if (young)
1801 region_elapsed_time_ms += predict_young_other_time_ms(1);
1802 else
1803 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1804
1805 return region_elapsed_time_ms;
1806 }
1807
1808 size_t
1809 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1810 size_t bytes_to_copy;
1811 if (hr->is_marked())
1812 bytes_to_copy = hr->max_live_bytes();
1813 else {
1814 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1815 "invariant" );
1816 int age = hr->age_in_surv_rate_group();
1817 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1818 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1819 }
1820
1821 return bytes_to_copy;
1822 }
1823
1824 void
1825 G1CollectorPolicy::start_recording_regions() {
1826 _recorded_rs_lengths = 0;
1827 _recorded_young_regions = 0;
1828 _recorded_non_young_regions = 0;
1829
1830 #if PREDICTIONS_VERBOSE
1831 _recorded_marked_bytes = 0;
1832 _recorded_young_bytes = 0;
1833 _predicted_bytes_to_copy = 0;
1834 _predicted_rs_lengths = 0;
1835 _predicted_cards_scanned = 0;
1836 #endif // PREDICTIONS_VERBOSE
1837 }
1838
1839 void
1840 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1841 #if PREDICTIONS_VERBOSE
1842 if (!young) {
1843 _recorded_marked_bytes += hr->max_live_bytes();
1844 }
1845 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1846 #endif // PREDICTIONS_VERBOSE
1847
1848 size_t rs_length = hr->rem_set()->occupied();
1849 _recorded_rs_lengths += rs_length;
1850 }
1851
1852 void
1853 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1854 assert(!hr->is_young(), "should not call this");
1855 ++_recorded_non_young_regions;
1856 record_cset_region_info(hr, false);
1857 }
1858
1859 void
1860 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1861 _recorded_young_regions = n_regions;
1862 }
1863
1864 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1865 #if PREDICTIONS_VERBOSE
1866 _recorded_young_bytes = bytes;
1867 #endif // PREDICTIONS_VERBOSE
1868 }
1869
1870 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1871 _recorded_rs_lengths = rs_lengths;
1872 }
1873
1874 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1875 _predicted_bytes_to_copy = bytes;
1876 }
1877
1878 void
1879 G1CollectorPolicy::end_recording_regions() {
1880 // The _predicted_pause_time_ms field is referenced in code
1881 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1882 _predicted_pause_time_ms = -1.0;
1883
1884 #if PREDICTIONS_VERBOSE
1885 _predicted_pending_cards = predict_pending_cards();
1886 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1887 if (full_young_gcs())
1888 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1889 else
1890 _predicted_cards_scanned +=
1891 predict_non_young_card_num(_predicted_rs_lengths);
1892 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1893
1894 _predicted_rs_update_time_ms =
1895 predict_rs_update_time_ms(_g1->pending_card_num());
1896 _predicted_rs_scan_time_ms =
1897 predict_rs_scan_time_ms(_predicted_cards_scanned);
1898 _predicted_object_copy_time_ms =
1899 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1900 _predicted_constant_other_time_ms =
1901 predict_constant_other_time_ms();
1902 _predicted_young_other_time_ms =
1903 predict_young_other_time_ms(_recorded_young_regions);
1904 _predicted_non_young_other_time_ms =
1905 predict_non_young_other_time_ms(_recorded_non_young_regions);
1906
1907 _predicted_pause_time_ms =
1908 _predicted_rs_update_time_ms +
1909 _predicted_rs_scan_time_ms +
1910 _predicted_object_copy_time_ms +
1911 _predicted_constant_other_time_ms +
1912 _predicted_young_other_time_ms +
1913 _predicted_non_young_other_time_ms;
1914 #endif // PREDICTIONS_VERBOSE
1915 }
1916
1917 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1918 predicted_time_ms) {
1919 // I don't think we need to do this when in young GC mode since
1920 // marking will be initiated next time we hit the soft limit anyway...
1921 if (predicted_time_ms > _expensive_region_limit_ms) {
1922 if (!in_young_gc_mode()) {
1923 set_full_young_gcs(true);
1924 // We might want to do something different here. However,
1925 // right now we don't support the non-generational G1 mode
1926 // (and in fact we are planning to remove the associated code,
1927 // see CR 6814390). So, let's leave it as is and this will be
1928 // removed some time in the future
1929 ShouldNotReachHere();
1930 set_during_initial_mark_pause();
1931 } else
1932 // no point in doing another partial one
1933 _should_revert_to_full_young_gcs = true;
1934 }
1935 }
1936
1937 // </NEW PREDICTION>
1938
1939
1940 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1941 double elapsed_ms) {
1942 _recent_gc_times_ms->add(elapsed_ms);
1943 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1944 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1945 }
1946
1947 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1948 if (_recent_pause_times_ms->num() == 0) {
1949 return (double) MaxGCPauseMillis;
1950 }
1951 return _recent_pause_times_ms->avg();
1952 }
1953
1954 double G1CollectorPolicy::recent_avg_time_for_rs_scan_ms() {
1955 if (_recent_rs_scan_times_ms->num() == 0) {
1956 return (double)MaxGCPauseMillis/3.0;
1957 }
1958 return _recent_rs_scan_times_ms->avg();
1959 }
1960
1961 int G1CollectorPolicy::number_of_recent_gcs() {
1962 assert(_recent_rs_scan_times_ms->num() ==
1963 _recent_pause_times_ms->num(), "Sequence out of sync");
1964 assert(_recent_pause_times_ms->num() ==
1965 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1966 assert(_recent_CS_bytes_used_before->num() ==
1967 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1968
1969 return _recent_pause_times_ms->num();
1970 }
1971
1972 double G1CollectorPolicy::recent_avg_survival_fraction() {
1973 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1974 _recent_CS_bytes_used_before);
1975 }
1976
1977 double G1CollectorPolicy::last_survival_fraction() {
1978 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1979 _recent_CS_bytes_used_before);
1980 }
1981
1982 double
1983 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1984 TruncatedSeq* before) {
1985 assert(surviving->num() == before->num(), "Sequence out of sync");
1986 if (before->sum() > 0.0) {
1987 double recent_survival_rate = surviving->sum() / before->sum();
1988 // We exempt parallel collection from this check because Alloc Buffer
1989 // fragmentation can produce negative collections.
1990 // Further, we're now always doing parallel collection. But I'm still
1991 // leaving this here as a placeholder for a more precise assertion later.
1992 // (DLD, 10/05.)
1993 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1994 _g1->evacuation_failed() ||
1995 recent_survival_rate <= 1.0, "Or bad frac");
1996 return recent_survival_rate;
1997 } else {
1998 return 1.0; // Be conservative.
1999 }
2000 }
2001
2002 double
2003 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
2004 TruncatedSeq* before) {
2005 assert(surviving->num() == before->num(), "Sequence out of sync");
2006 if (surviving->num() > 0 && before->last() > 0.0) {
2007 double last_survival_rate = surviving->last() / before->last();
2008 // We exempt parallel collection from this check because Alloc Buffer
2009 // fragmentation can produce negative collections.
2010 // Further, we're now always doing parallel collection. But I'm still
2011 // leaving this here as a placeholder for a more precise assertion later.
2012 // (DLD, 10/05.)
2013 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
2014 last_survival_rate <= 1.0, "Or bad frac");
2015 return last_survival_rate;
2016 } else {
2017 return 1.0;
2018 }
2019 }
2020
2021 static const int survival_min_obs = 5;
2022 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
2023 static const double min_survival_rate = 0.1;
2024
2025 double
2026 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
2027 double latest) {
2028 double res = avg;
2029 if (number_of_recent_gcs() < survival_min_obs) {
2030 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
2031 }
2032 res = MAX2(res, latest);
2033 res = MAX2(res, min_survival_rate);
2034 // In the parallel case, LAB fragmentation can produce "negative
2035 // collections"; so can evac failure. Cap at 1.0
2036 res = MIN2(res, 1.0);
2037 return res;
2038 }
2039
2040 size_t G1CollectorPolicy::expansion_amount() {
2041 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
2042 // We will double the existing space, or take
2043 // G1ExpandByPercentOfAvailable % of the available expansion
2044 // space, whichever is smaller, bounded below by a minimum
2045 // expansion (unless that's all that's left.)
2046 const size_t min_expand_bytes = 1*M;
2047 size_t reserved_bytes = _g1->max_capacity();
2048 size_t committed_bytes = _g1->capacity();
2049 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2050 size_t expand_bytes;
2051 size_t expand_bytes_via_pct =
2052 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2053 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2054 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2055 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2056 if (G1PolicyVerbose > 1) {
2057 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2058 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2059 " Answer = %d.\n",
2060 recent_avg_pause_time_ratio(),
2061 byte_size_in_proper_unit(committed_bytes),
2062 proper_unit_for_byte_size(committed_bytes),
2063 byte_size_in_proper_unit(uncommitted_bytes),
2064 proper_unit_for_byte_size(uncommitted_bytes),
2065 byte_size_in_proper_unit(expand_bytes_via_pct),
2066 proper_unit_for_byte_size(expand_bytes_via_pct),
2067 byte_size_in_proper_unit(expand_bytes),
2068 proper_unit_for_byte_size(expand_bytes));
2069 }
2070 return expand_bytes;
2071 } else {
2072 return 0;
2073 }
2074 }
2075
2076 void G1CollectorPolicy::note_start_of_mark_thread() {
2077 _mark_thread_startup_sec = os::elapsedTime();
2078 }
2079
2080 class CountCSClosure: public HeapRegionClosure {
2081 G1CollectorPolicy* _g1_policy;
2082 public:
2083 CountCSClosure(G1CollectorPolicy* g1_policy) :
2084 _g1_policy(g1_policy) {}
2085 bool doHeapRegion(HeapRegion* r) {
2086 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2087 return false;
2088 }
2089 };
2090
2091 void G1CollectorPolicy::count_CS_bytes_used() {
2092 CountCSClosure cs_closure(this);
2093 _g1->collection_set_iterate(&cs_closure);
2094 }
2095
2096 void G1CollectorPolicy::print_summary (int level,
2097 const char* str,
2098 NumberSeq* seq) const {
2099 double sum = seq->sum();
2100 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2101 str, sum / 1000.0, seq->avg());
2102 }
2103
2104 void G1CollectorPolicy::print_summary_sd (int level,
2105 const char* str,
2106 NumberSeq* seq) const {
2107 print_summary(level, str, seq);
2108 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2109 seq->num(), seq->sd(), seq->maximum());
2110 }
2111
2112 void G1CollectorPolicy::check_other_times(int level,
2113 NumberSeq* other_times_ms,
2114 NumberSeq* calc_other_times_ms) const {
2115 bool should_print = false;
2116 LineBuffer buf(level + 2);
2117
2118 double max_sum = MAX2(fabs(other_times_ms->sum()),
2119 fabs(calc_other_times_ms->sum()));
2120 double min_sum = MIN2(fabs(other_times_ms->sum()),
2121 fabs(calc_other_times_ms->sum()));
2122 double sum_ratio = max_sum / min_sum;
2123 if (sum_ratio > 1.1) {
2124 should_print = true;
2125 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2126 }
2127
2128 double max_avg = MAX2(fabs(other_times_ms->avg()),
2129 fabs(calc_other_times_ms->avg()));
2130 double min_avg = MIN2(fabs(other_times_ms->avg()),
2131 fabs(calc_other_times_ms->avg()));
2132 double avg_ratio = max_avg / min_avg;
2133 if (avg_ratio > 1.1) {
2134 should_print = true;
2135 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2136 }
2137
2138 if (other_times_ms->sum() < -0.01) {
2139 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2140 }
2141
2142 if (other_times_ms->avg() < -0.01) {
2143 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2144 }
2145
2146 if (calc_other_times_ms->sum() < -0.01) {
2147 should_print = true;
2148 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2149 }
2150
2151 if (calc_other_times_ms->avg() < -0.01) {
2152 should_print = true;
2153 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2154 }
2155
2156 if (should_print)
2157 print_summary(level, "Other(Calc)", calc_other_times_ms);
2158 }
2159
2160 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2161 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
2162 MainBodySummary* body_summary = summary->main_body_summary();
2163 if (summary->get_total_seq()->num() > 0) {
2164 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2165 if (body_summary != NULL) {
2166 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2167 if (parallel) {
2168 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2169 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2170 print_summary(2, "Ext Root Scanning",
2171 body_summary->get_ext_root_scan_seq());
2172 print_summary(2, "Mark Stack Scanning",
2173 body_summary->get_mark_stack_scan_seq());
2174 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2175 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2176 print_summary(2, "Termination", body_summary->get_termination_seq());
2177 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2178 {
2179 NumberSeq* other_parts[] = {
2180 body_summary->get_update_rs_seq(),
2181 body_summary->get_ext_root_scan_seq(),
2182 body_summary->get_mark_stack_scan_seq(),
2183 body_summary->get_scan_rs_seq(),
2184 body_summary->get_obj_copy_seq(),
2185 body_summary->get_termination_seq()
2186 };
2187 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2188 6, other_parts);
2189 check_other_times(2, body_summary->get_parallel_other_seq(),
2190 &calc_other_times_ms);
2191 }
2192 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2193 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2194 } else {
2195 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2196 print_summary(1, "Ext Root Scanning",
2197 body_summary->get_ext_root_scan_seq());
2198 print_summary(1, "Mark Stack Scanning",
2199 body_summary->get_mark_stack_scan_seq());
2200 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2201 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2202 }
2203 }
2204 print_summary(1, "Other", summary->get_other_seq());
2205 {
2206 if (body_summary != NULL) {
2207 NumberSeq calc_other_times_ms;
2208 if (parallel) {
2209 // parallel
2210 NumberSeq* other_parts[] = {
2211 body_summary->get_satb_drain_seq(),
2212 body_summary->get_parallel_seq(),
2213 body_summary->get_clear_ct_seq()
2214 };
2215 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2216 3, other_parts);
2217 } else {
2218 // serial
2219 NumberSeq* other_parts[] = {
2220 body_summary->get_satb_drain_seq(),
2221 body_summary->get_update_rs_seq(),
2222 body_summary->get_ext_root_scan_seq(),
2223 body_summary->get_mark_stack_scan_seq(),
2224 body_summary->get_scan_rs_seq(),
2225 body_summary->get_obj_copy_seq()
2226 };
2227 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2228 6, other_parts);
2229 }
2230 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2231 }
2232 }
2233 } else {
2234 LineBuffer(1).append_and_print_cr("none");
2235 }
2236 LineBuffer(0).append_and_print_cr("");
2237 }
2238
2239 void G1CollectorPolicy::print_tracing_info() const {
2240 if (TraceGen0Time) {
2241 gclog_or_tty->print_cr("ALL PAUSES");
2242 print_summary_sd(0, "Total", _all_pause_times_ms);
2243 gclog_or_tty->print_cr("");
2244 gclog_or_tty->print_cr("");
2245 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2246 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2247 gclog_or_tty->print_cr("");
2248
2249 gclog_or_tty->print_cr("EVACUATION PAUSES");
2250 print_summary(_summary);
2251
2252 gclog_or_tty->print_cr("MISC");
2253 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2254 print_summary_sd(0, "Yields", _all_yield_times_ms);
2255 for (int i = 0; i < _aux_num; ++i) {
2256 if (_all_aux_times_ms[i].num() > 0) {
2257 char buffer[96];
2258 sprintf(buffer, "Aux%d", i);
2259 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2260 }
2261 }
2262
2263 size_t all_region_num = _region_num_young + _region_num_tenured;
2264 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2265 "Tenured %8d (%6.2lf%%)",
2266 all_region_num,
2267 _region_num_young,
2268 (double) _region_num_young / (double) all_region_num * 100.0,
2269 _region_num_tenured,
2270 (double) _region_num_tenured / (double) all_region_num * 100.0);
2271 }
2272 if (TraceGen1Time) {
2273 if (_all_full_gc_times_ms->num() > 0) {
2274 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2275 _all_full_gc_times_ms->num(),
2276 _all_full_gc_times_ms->sum() / 1000.0);
2277 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2278 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2279 _all_full_gc_times_ms->sd(),
2280 _all_full_gc_times_ms->maximum());
2281 }
2282 }
2283 }
2284
2285 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2286 #ifndef PRODUCT
2287 _short_lived_surv_rate_group->print_surv_rate_summary();
2288 // add this call for any other surv rate groups
2289 #endif // PRODUCT
2290 }
2291
2292 void
2293 G1CollectorPolicy::update_region_num(bool young) {
2294 if (young) {
2295 ++_region_num_young;
2296 } else {
2297 ++_region_num_tenured;
2298 }
2299 }
2300
2301 #ifndef PRODUCT
2302 // for debugging, bit of a hack...
2303 static char*
2304 region_num_to_mbs(int length) {
2305 static char buffer[64];
2306 double bytes = (double) (length * HeapRegion::GrainBytes);
2307 double mbs = bytes / (double) (1024 * 1024);
2308 sprintf(buffer, "%7.2lfMB", mbs);
2309 return buffer;
2310 }
2311 #endif // PRODUCT
2312
2313 size_t G1CollectorPolicy::max_regions(int purpose) {
2314 switch (purpose) {
2315 case GCAllocForSurvived:
2316 return _max_survivor_regions;
2317 case GCAllocForTenured:
2318 return REGIONS_UNLIMITED;
2319 default:
2320 ShouldNotReachHere();
2321 return REGIONS_UNLIMITED;
2322 };
2323 }
2324
2325 void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
2326 size_t expansion_region_num = 0;
2327 if (GCLockerEdenExpansionPercent > 0) {
2328 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2329 double expansion_region_num_d = perc * (double) _young_list_target_length;
2330 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2331 // less than 1.0) we'll get 1.
2332 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2333 } else {
2334 assert(expansion_region_num == 0, "sanity");
2335 }
2336 _young_list_max_length = _young_list_target_length + expansion_region_num;
2337 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2338 }
2339
2340 // Calculates survivor space parameters.
2341 void G1CollectorPolicy::calculate_survivors_policy()
2342 {
2343 if (G1FixedSurvivorSpaceSize == 0) {
2344 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2345 } else {
2346 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2347 }
2348
2349 if (G1FixedTenuringThreshold) {
2350 _tenuring_threshold = MaxTenuringThreshold;
2351 } else {
2352 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2353 HeapRegion::GrainWords * _max_survivor_regions);
2354 }
2355 }
2356
2357 #ifndef PRODUCT
2358 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2359 CollectionSetChooser* _chooser;
2360 public:
2361 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2362 _chooser(chooser) {}
2363
2364 bool doHeapRegion(HeapRegion* r) {
2365 if (!r->continuesHumongous()) {
2366 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2367 }
2368 return false;
2369 }
2370 };
2371
2372 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2373 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2374 _g1->heap_region_iterate(&cl);
2375 return true;
2376 }
2377 #endif
2378
2379 bool
2380 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2381 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2382 if (!during_cycle) {
2383 set_initiate_conc_mark_if_possible();
2384 return true;
2385 } else {
2386 return false;
2387 }
2388 }
2389
2390 void
2391 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2392 // We are about to decide on whether this pause will be an
2393 // initial-mark pause.
2394
2395 // First, during_initial_mark_pause() should not be already set. We
2396 // will set it here if we have to. However, it should be cleared by
2397 // the end of the pause (it's only set for the duration of an
2398 // initial-mark pause).
2399 assert(!during_initial_mark_pause(), "pre-condition");
2400
2401 if (initiate_conc_mark_if_possible()) {
2402 // We had noticed on a previous pause that the heap occupancy has
2403 // gone over the initiating threshold and we should start a
2404 // concurrent marking cycle. So we might initiate one.
2405
2406 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2407 if (!during_cycle) {
2408 // The concurrent marking thread is not "during a cycle", i.e.,
2409 // it has completed the last one. So we can go ahead and
2410 // initiate a new cycle.
2411
2412 set_during_initial_mark_pause();
2413
2414 // And we can now clear initiate_conc_mark_if_possible() as
2415 // we've already acted on it.
2416 clear_initiate_conc_mark_if_possible();
2417 } else {
2418 // The concurrent marking thread is still finishing up the
2419 // previous cycle. If we start one right now the two cycles
2420 // overlap. In particular, the concurrent marking thread might
2421 // be in the process of clearing the next marking bitmap (which
2422 // we will use for the next cycle if we start one). Starting a
2423 // cycle now will be bad given that parts of the marking
2424 // information might get cleared by the marking thread. And we
2425 // cannot wait for the marking thread to finish the cycle as it
2426 // periodically yields while clearing the next marking bitmap
2427 // and, if it's in a yield point, it's waiting for us to
2428 // finish. So, at this point we will not start a cycle and we'll
2429 // let the concurrent marking thread complete the last one.
2430 }
2431 }
2432 }
2433
2434 void
2435 G1CollectorPolicy_BestRegionsFirst::
2436 record_collection_pause_start(double start_time_sec, size_t start_used) {
2437 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2438 }
2439
2440 class KnownGarbageClosure: public HeapRegionClosure {
2441 CollectionSetChooser* _hrSorted;
2442
2443 public:
2444 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2445 _hrSorted(hrSorted)
2446 {}
2447
2448 bool doHeapRegion(HeapRegion* r) {
2449 // We only include humongous regions in collection
2450 // sets when concurrent mark shows that their contained object is
2451 // unreachable.
2452
2453 // Do we have any marking information for this region?
2454 if (r->is_marked()) {
2455 // We don't include humongous regions in collection
2456 // sets because we collect them immediately at the end of a marking
2457 // cycle. We also don't include young regions because we *must*
2458 // include them in the next collection pause.
2459 if (!r->isHumongous() && !r->is_young()) {
2460 _hrSorted->addMarkedHeapRegion(r);
2461 }
2462 }
2463 return false;
2464 }
2465 };
2466
2467 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2468 CollectionSetChooser* _hrSorted;
2469 jint _marked_regions_added;
2470 jint _chunk_size;
2471 jint _cur_chunk_idx;
2472 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2473 int _worker;
2474 int _invokes;
2475
2476 void get_new_chunk() {
2477 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2478 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2479 }
2480 void add_region(HeapRegion* r) {
2481 if (_cur_chunk_idx == _cur_chunk_end) {
2482 get_new_chunk();
2483 }
2484 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2485 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2486 _marked_regions_added++;
2487 _cur_chunk_idx++;
2488 }
2489
2490 public:
2491 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2492 jint chunk_size,
2493 int worker) :
2494 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2495 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2496 _invokes(0)
2497 {}
2498
2499 bool doHeapRegion(HeapRegion* r) {
2500 // We only include humongous regions in collection
2501 // sets when concurrent mark shows that their contained object is
2502 // unreachable.
2503 _invokes++;
2504
2505 // Do we have any marking information for this region?
2506 if (r->is_marked()) {
2507 // We don't include humongous regions in collection
2508 // sets because we collect them immediately at the end of a marking
2509 // cycle.
2510 // We also do not include young regions in collection sets
2511 if (!r->isHumongous() && !r->is_young()) {
2512 add_region(r);
2513 }
2514 }
2515 return false;
2516 }
2517 jint marked_regions_added() { return _marked_regions_added; }
2518 int invokes() { return _invokes; }
2519 };
2520
2521 class ParKnownGarbageTask: public AbstractGangTask {
2522 CollectionSetChooser* _hrSorted;
2523 jint _chunk_size;
2524 G1CollectedHeap* _g1;
2525 public:
2526 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2527 AbstractGangTask("ParKnownGarbageTask"),
2528 _hrSorted(hrSorted), _chunk_size(chunk_size),
2529 _g1(G1CollectedHeap::heap())
2530 {}
2531
2532 void work(int i) {
2533 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2534 // Back to zero for the claim value.
2535 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2536 HeapRegion::InitialClaimValue);
2537 jint regions_added = parKnownGarbageCl.marked_regions_added();
2538 _hrSorted->incNumMarkedHeapRegions(regions_added);
2539 if (G1PrintParCleanupStats) {
2540 gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
2541 i, parKnownGarbageCl.invokes(), regions_added);
2542 }
2543 }
2544 };
2545
2546 void
2547 G1CollectorPolicy_BestRegionsFirst::
2548 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2549 size_t max_live_bytes) {
2550 double start;
2551 if (G1PrintParCleanupStats) start = os::elapsedTime();
2552 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2553
2554 _collectionSetChooser->clearMarkedHeapRegions();
2555 double clear_marked_end;
2556 if (G1PrintParCleanupStats) {
2557 clear_marked_end = os::elapsedTime();
2558 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2559 (clear_marked_end - start)*1000.0);
2560 }
2561 if (G1CollectedHeap::use_parallel_gc_threads()) {
2562 const size_t OverpartitionFactor = 4;
2563 const size_t MinWorkUnit = 8;
2564 const size_t WorkUnit =
2565 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2566 MinWorkUnit);
2567 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2568 WorkUnit);
2569 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2570 (int) WorkUnit);
2571 _g1->workers()->run_task(&parKnownGarbageTask);
2572
2573 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2574 "sanity check");
2575 } else {
2576 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2577 _g1->heap_region_iterate(&knownGarbagecl);
2578 }
2579 double known_garbage_end;
2580 if (G1PrintParCleanupStats) {
2581 known_garbage_end = os::elapsedTime();
2582 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2583 (known_garbage_end - clear_marked_end)*1000.0);
2584 }
2585 _collectionSetChooser->sortMarkedHeapRegions();
2586 double sort_end;
2587 if (G1PrintParCleanupStats) {
2588 sort_end = os::elapsedTime();
2589 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2590 (sort_end - known_garbage_end)*1000.0);
2591 }
2592
2593 record_concurrent_mark_cleanup_end_work2();
2594 double work2_end;
2595 if (G1PrintParCleanupStats) {
2596 work2_end = os::elapsedTime();
2597 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2598 (work2_end - sort_end)*1000.0);
2599 }
2600 }
2601
2602 // Add the heap region at the head of the non-incremental collection set
2603 void G1CollectorPolicy::
2604 add_to_collection_set(HeapRegion* hr) {
2605 assert(_inc_cset_build_state == Active, "Precondition");
2606 assert(!hr->is_young(), "non-incremental add of young region");
2607
2608 if (_g1->mark_in_progress())
2609 _g1->concurrent_mark()->registerCSetRegion(hr);
2610
2611 assert(!hr->in_collection_set(), "should not already be in the CSet");
2612 hr->set_in_collection_set(true);
2613 hr->set_next_in_collection_set(_collection_set);
2614 _collection_set = hr;
2615 _collection_set_size++;
2616 _collection_set_bytes_used_before += hr->used();
2617 _g1->register_region_with_in_cset_fast_test(hr);
2618 }
2619
2620 // Initialize the per-collection-set information
2621 void G1CollectorPolicy::start_incremental_cset_building() {
2622 assert(_inc_cset_build_state == Inactive, "Precondition");
2623
2624 _inc_cset_head = NULL;
2625 _inc_cset_tail = NULL;
2626 _inc_cset_size = 0;
2627 _inc_cset_bytes_used_before = 0;
2628
2629 if (in_young_gc_mode()) {
2630 _inc_cset_young_index = 0;
2631 }
2632
2633 _inc_cset_max_finger = 0;
2634 _inc_cset_recorded_young_bytes = 0;
2635 _inc_cset_recorded_rs_lengths = 0;
2636 _inc_cset_predicted_elapsed_time_ms = 0;
2637 _inc_cset_predicted_bytes_to_copy = 0;
2638 _inc_cset_build_state = Active;
2639 }
2640
2641 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2642 // This routine is used when:
2643 // * adding survivor regions to the incremental cset at the end of an
2644 // evacuation pause,
2645 // * adding the current allocation region to the incremental cset
2646 // when it is retired, and
2647 // * updating existing policy information for a region in the
2648 // incremental cset via young list RSet sampling.
2649 // Therefore this routine may be called at a safepoint by the
2650 // VM thread, or in-between safepoints by mutator threads (when
2651 // retiring the current allocation region) or a concurrent
2652 // refine thread (RSet sampling).
2653
2654 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2655 size_t used_bytes = hr->used();
2656
2657 _inc_cset_recorded_rs_lengths += rs_length;
2658 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2659
2660 _inc_cset_bytes_used_before += used_bytes;
2661
2662 // Cache the values we have added to the aggregated informtion
2663 // in the heap region in case we have to remove this region from
2664 // the incremental collection set, or it is updated by the
2665 // rset sampling code
2666 hr->set_recorded_rs_length(rs_length);
2667 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2668
2669 #if PREDICTIONS_VERBOSE
2670 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2671 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2672
2673 // Record the number of bytes used in this region
2674 _inc_cset_recorded_young_bytes += used_bytes;
2675
2676 // Cache the values we have added to the aggregated informtion
2677 // in the heap region in case we have to remove this region from
2678 // the incremental collection set, or it is updated by the
2679 // rset sampling code
2680 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2681 #endif // PREDICTIONS_VERBOSE
2682 }
2683
2684 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2685 // This routine is currently only called as part of the updating of
2686 // existing policy information for regions in the incremental cset that
2687 // is performed by the concurrent refine thread(s) as part of young list
2688 // RSet sampling. Therefore we should not be at a safepoint.
2689
2690 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2691 assert(hr->is_young(), "it should be");
2692
2693 size_t used_bytes = hr->used();
2694 size_t old_rs_length = hr->recorded_rs_length();
2695 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2696
2697 // Subtract the old recorded/predicted policy information for
2698 // the given heap region from the collection set info.
2699 _inc_cset_recorded_rs_lengths -= old_rs_length;
2700 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2701
2702 _inc_cset_bytes_used_before -= used_bytes;
2703
2704 // Clear the values cached in the heap region
2705 hr->set_recorded_rs_length(0);
2706 hr->set_predicted_elapsed_time_ms(0);
2707
2708 #if PREDICTIONS_VERBOSE
2709 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2710 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2711
2712 // Subtract the number of bytes used in this region
2713 _inc_cset_recorded_young_bytes -= used_bytes;
2714
2715 // Clear the values cached in the heap region
2716 hr->set_predicted_bytes_to_copy(0);
2717 #endif // PREDICTIONS_VERBOSE
2718 }
2719
2720 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2721 // Update the collection set information that is dependent on the new RS length
2722 assert(hr->is_young(), "Precondition");
2723
2724 remove_from_incremental_cset_info(hr);
2725 add_to_incremental_cset_info(hr, new_rs_length);
2726 }
2727
2728 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2729 assert( hr->is_young(), "invariant");
2730 assert( hr->young_index_in_cset() == -1, "invariant" );
2731 assert(_inc_cset_build_state == Active, "Precondition");
2732
2733 // We need to clear and set the cached recorded/cached collection set
2734 // information in the heap region here (before the region gets added
2735 // to the collection set). An individual heap region's cached values
2736 // are calculated, aggregated with the policy collection set info,
2737 // and cached in the heap region here (initially) and (subsequently)
2738 // by the Young List sampling code.
2739
2740 size_t rs_length = hr->rem_set()->occupied();
2741 add_to_incremental_cset_info(hr, rs_length);
2742
2743 HeapWord* hr_end = hr->end();
2744 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2745
2746 assert(!hr->in_collection_set(), "invariant");
2747 hr->set_in_collection_set(true);
2748 assert( hr->next_in_collection_set() == NULL, "invariant");
2749
2750 _inc_cset_size++;
2751 _g1->register_region_with_in_cset_fast_test(hr);
2752
2753 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2754 ++_inc_cset_young_index;
2755 }
2756
2757 // Add the region at the RHS of the incremental cset
2758 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2759 // We should only ever be appending survivors at the end of a pause
2760 assert( hr->is_survivor(), "Logic");
2761
2762 // Do the 'common' stuff
2763 add_region_to_incremental_cset_common(hr);
2764
2765 // Now add the region at the right hand side
2766 if (_inc_cset_tail == NULL) {
2767 assert(_inc_cset_head == NULL, "invariant");
2768 _inc_cset_head = hr;
2769 } else {
2770 _inc_cset_tail->set_next_in_collection_set(hr);
2771 }
2772 _inc_cset_tail = hr;
2773 }
2774
2775 // Add the region to the LHS of the incremental cset
2776 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2777 // Survivors should be added to the RHS at the end of a pause
2778 assert(!hr->is_survivor(), "Logic");
2779
2780 // Do the 'common' stuff
2781 add_region_to_incremental_cset_common(hr);
2782
2783 // Add the region at the left hand side
2784 hr->set_next_in_collection_set(_inc_cset_head);
2785 if (_inc_cset_head == NULL) {
2786 assert(_inc_cset_tail == NULL, "Invariant");
2787 _inc_cset_tail = hr;
2788 }
2789 _inc_cset_head = hr;
2790 }
2791
2792 #ifndef PRODUCT
2793 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2794 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2795
2796 st->print_cr("\nCollection_set:");
2797 HeapRegion* csr = list_head;
2798 while (csr != NULL) {
2799 HeapRegion* next = csr->next_in_collection_set();
2800 assert(csr->in_collection_set(), "bad CS");
2801 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2802 "age: %4d, y: %d, surv: %d",
2803 csr->bottom(), csr->end(),
2804 csr->top(),
2805 csr->prev_top_at_mark_start(),
2806 csr->next_top_at_mark_start(),
2807 csr->top_at_conc_mark_count(),
2808 csr->age_in_surv_rate_group_cond(),
2809 csr->is_young(),
2810 csr->is_survivor());
2811 csr = next;
2812 }
2813 }
2814 #endif // !PRODUCT
2815
2816 void
2817 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2818 double target_pause_time_ms) {
2819 // Set this here - in case we're not doing young collections.
2820 double non_young_start_time_sec = os::elapsedTime();
2821
2822 start_recording_regions();
2823
2824 guarantee(target_pause_time_ms > 0.0,
2825 err_msg("target_pause_time_ms = %1.6lf should be positive",
2826 target_pause_time_ms));
2827 guarantee(_collection_set == NULL, "Precondition");
2828
2829 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2830 double predicted_pause_time_ms = base_time_ms;
2831
2832 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2833
2834 // the 10% and 50% values are arbitrary...
2835 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2836 time_remaining_ms = 0.50 * target_pause_time_ms;
2837 _within_target = false;
2838 } else {
2839 _within_target = true;
2840 }
2841
2842 // We figure out the number of bytes available for future to-space.
2843 // For new regions without marking information, we must assume the
2844 // worst-case of complete survival. If we have marking information for a
2845 // region, we can bound the amount of live data. We can add a number of
2846 // such regions, as long as the sum of the live data bounds does not
2847 // exceed the available evacuation space.
2848 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2849
2850 size_t expansion_bytes =
2851 _g1->expansion_regions() * HeapRegion::GrainBytes;
2852
2853 _collection_set_bytes_used_before = 0;
2854 _collection_set_size = 0;
2855
2856 // Adjust for expansion and slop.
2857 max_live_bytes = max_live_bytes + expansion_bytes;
2858
2859 HeapRegion* hr;
2860 if (in_young_gc_mode()) {
2861 double young_start_time_sec = os::elapsedTime();
2862
2863 if (G1PolicyVerbose > 0) {
2864 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2865 _g1->young_list()->length());
2866 }
2867
2868 _young_cset_length = 0;
2869 _last_young_gc_full = full_young_gcs() ? true : false;
2870
2871 if (_last_young_gc_full)
2872 ++_full_young_pause_num;
2873 else
2874 ++_partial_young_pause_num;
2875
2876 // The young list is laid with the survivor regions from the previous
2877 // pause are appended to the RHS of the young list, i.e.
2878 // [Newly Young Regions ++ Survivors from last pause].
2879
2880 hr = _g1->young_list()->first_survivor_region();
2881 while (hr != NULL) {
2882 assert(hr->is_survivor(), "badly formed young list");
2883 hr->set_young();
2884 hr = hr->get_next_young_region();
2885 }
2886
2887 // Clear the fields that point to the survivor list - they are
2888 // all young now.
2889 _g1->young_list()->clear_survivors();
2890
2891 if (_g1->mark_in_progress())
2892 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2893
2894 _young_cset_length = _inc_cset_young_index;
2895 _collection_set = _inc_cset_head;
2896 _collection_set_size = _inc_cset_size;
2897 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2898
2899 // For young regions in the collection set, we assume the worst
2900 // case of complete survival
2901 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2902
2903 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2904 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2905
2906 // The number of recorded young regions is the incremental
2907 // collection set's current size
2908 set_recorded_young_regions(_inc_cset_size);
2909 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2910 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2911 #if PREDICTIONS_VERBOSE
2912 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2913 #endif // PREDICTIONS_VERBOSE
2914
2915 if (G1PolicyVerbose > 0) {
2916 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2917 _inc_cset_size);
2918 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2919 max_live_bytes/K);
2920 }
2921
2922 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2923
2924 double young_end_time_sec = os::elapsedTime();
2925 _recorded_young_cset_choice_time_ms =
2926 (young_end_time_sec - young_start_time_sec) * 1000.0;
2927
2928 // We are doing young collections so reset this.
2929 non_young_start_time_sec = young_end_time_sec;
2930
2931 // Note we can use either _collection_set_size or
2932 // _young_cset_length here
2933 if (_collection_set_size > 0 && _last_young_gc_full) {
2934 // don't bother adding more regions...
2935 goto choose_collection_set_end;
2936 }
2937 }
2938
2939 if (!in_young_gc_mode() || !full_young_gcs()) {
2940 bool should_continue = true;
2941 NumberSeq seq;
2942 double avg_prediction = 100000000000000000.0; // something very large
2943
2944 do {
2945 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2946 avg_prediction);
2947 if (hr != NULL) {
2948 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2949 time_remaining_ms -= predicted_time_ms;
2950 predicted_pause_time_ms += predicted_time_ms;
2951 add_to_collection_set(hr);
2952 record_non_young_cset_region(hr);
2953 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2954 if (G1PolicyVerbose > 0) {
2955 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2956 max_live_bytes/K);
2957 }
2958 seq.add(predicted_time_ms);
2959 avg_prediction = seq.avg() + seq.sd();
2960 }
2961 should_continue =
2962 ( hr != NULL) &&
2963 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
2964 : _collection_set_size < _young_list_fixed_length );
2965 } while (should_continue);
2966
2967 if (!adaptive_young_list_length() &&
2968 _collection_set_size < _young_list_fixed_length)
2969 _should_revert_to_full_young_gcs = true;
2970 }
2971
2972 choose_collection_set_end:
2973 stop_incremental_cset_building();
2974
2975 count_CS_bytes_used();
2976
2977 end_recording_regions();
2978
2979 double non_young_end_time_sec = os::elapsedTime();
2980 _recorded_non_young_cset_choice_time_ms =
2981 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2982 }
2983
2984 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
2985 G1CollectorPolicy::record_full_collection_end();
2986 _collectionSetChooser->updateAfterFullCollection();
2987 }
2988
2989 void G1CollectorPolicy_BestRegionsFirst::
2990 expand_if_possible(size_t numRegions) {
2991 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
2992 _g1->expand(expansion_bytes);
2993 }
2994
2995 void G1CollectorPolicy_BestRegionsFirst::
2996 record_collection_pause_end() {
2997 G1CollectorPolicy::record_collection_pause_end();
2998 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
2999 }