1 /*
2 * Copyright (c) 2001, 2010, 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 G1CollectorPolicy::G1CollectorPolicy() :
85 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
86 ? ParallelGCThreads : 1),
87
88
89 _n_pauses(0),
90 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
91 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
92 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
93 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
94 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
95 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
96 _all_pause_times_ms(new NumberSeq()),
97 _stop_world_start(0.0),
98 _all_stop_world_times_ms(new NumberSeq()),
99 _all_yield_times_ms(new NumberSeq()),
100
101 _all_mod_union_times_ms(new NumberSeq()),
102
103 _summary(new Summary()),
104
105 #ifndef PRODUCT
106 _cur_clear_ct_time_ms(0.0),
107 _min_clear_cc_time_ms(-1.0),
108 _max_clear_cc_time_ms(-1.0),
109 _cur_clear_cc_time_ms(0.0),
110 _cum_clear_cc_time_ms(0.0),
111 _num_cc_clears(0L),
112 #endif
113
114 _region_num_young(0),
115 _region_num_tenured(0),
116 _prev_region_num_young(0),
117 _prev_region_num_tenured(0),
118
119 _aux_num(10),
120 _all_aux_times_ms(new NumberSeq[_aux_num]),
121 _cur_aux_start_times_ms(new double[_aux_num]),
122 _cur_aux_times_ms(new double[_aux_num]),
123 _cur_aux_times_set(new bool[_aux_num]),
124
125 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
126 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
127 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
128
129 // <NEW PREDICTION>
130
131 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
132 _prev_collection_pause_end_ms(0.0),
133 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
134 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
135 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
136 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
137 _partially_young_cards_per_entry_ratio_seq(
138 new TruncatedSeq(TruncatedSeqLength)),
139 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
140 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
141 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
142 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
143 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
144 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
145 _non_young_other_cost_per_region_ms_seq(
146 new TruncatedSeq(TruncatedSeqLength)),
147
148 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
149 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
150 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
151
152 _pause_time_target_ms((double) MaxGCPauseMillis),
153
154 // </NEW PREDICTION>
155
156 _in_young_gc_mode(false),
157 _full_young_gcs(true),
158 _full_young_pause_num(0),
159 _partial_young_pause_num(0),
160
161 _during_marking(false),
162 _in_marking_window(false),
163 _in_marking_window_im(false),
164
165 _known_garbage_ratio(0.0),
166 _known_garbage_bytes(0),
167
168 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
169
170 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
171
172 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
173 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
174
175 _recent_avg_pause_time_ratio(0.0),
176 _num_markings(0),
177 _n_marks(0),
178 _n_pauses_at_mark_end(0),
179
180 _all_full_gc_times_ms(new NumberSeq()),
181
182 // G1PausesBtwnConcMark defaults to -1
183 // so the hack is to do the cast QQQ FIXME
184 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
185 _n_marks_since_last_pause(0),
186 _initiate_conc_mark_if_possible(false),
187 _during_initial_mark_pause(false),
188 _should_revert_to_full_young_gcs(false),
189 _last_full_young_gc(false),
190
191 _prev_collection_pause_used_at_end_bytes(0),
192
193 _collection_set(NULL),
194 _collection_set_size(0),
195 _collection_set_bytes_used_before(0),
196
197 // Incremental CSet attributes
198 _inc_cset_build_state(Inactive),
199 _inc_cset_head(NULL),
200 _inc_cset_tail(NULL),
201 _inc_cset_size(0),
202 _inc_cset_young_index(0),
203 _inc_cset_bytes_used_before(0),
204 _inc_cset_max_finger(NULL),
205 _inc_cset_recorded_young_bytes(0),
206 _inc_cset_recorded_rs_lengths(0),
207 _inc_cset_predicted_elapsed_time_ms(0.0),
208 _inc_cset_predicted_bytes_to_copy(0),
209
210 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
211 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
212 #endif // _MSC_VER
213
214 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
215 G1YoungSurvRateNumRegionsSummary)),
216 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
217 G1YoungSurvRateNumRegionsSummary)),
218 // add here any more surv rate groups
219 _recorded_survivor_regions(0),
220 _recorded_survivor_head(NULL),
221 _recorded_survivor_tail(NULL),
222 _survivors_age_table(true),
223
224 _gc_overhead_perc(0.0)
225
226 {
227 // Set up the region size and associated fields. Given that the
228 // policy is created before the heap, we have to set this up here,
229 // so it's done as soon as possible.
230 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
231 HeapRegionRemSet::setup_remset_size();
232
233 // Verify PLAB sizes
234 const uint region_size = HeapRegion::GrainWords;
235 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
236 char buffer[128];
237 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
238 OldPLABSize > region_size ? "Old" : "Young", region_size);
239 vm_exit_during_initialization(buffer);
240 }
241
242 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
243 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
244
245 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
246 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
247 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
248
249 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
250 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
251
252 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
253
254 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
255
256 _par_last_termination_times_ms = new double[_parallel_gc_threads];
257 _par_last_termination_attempts = new double[_parallel_gc_threads];
258 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
259
260 // start conservatively
261 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
262
263 // <NEW PREDICTION>
264
265 int index;
266 if (ParallelGCThreads == 0)
267 index = 0;
268 else if (ParallelGCThreads > 8)
269 index = 7;
270 else
271 index = ParallelGCThreads - 1;
272
273 _pending_card_diff_seq->add(0.0);
274 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
275 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
276 _fully_young_cards_per_entry_ratio_seq->add(
277 fully_young_cards_per_entry_ratio_defaults[index]);
278 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
279 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
280 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
281 _young_other_cost_per_region_ms_seq->add(
282 young_other_cost_per_region_ms_defaults[index]);
283 _non_young_other_cost_per_region_ms_seq->add(
284 non_young_other_cost_per_region_ms_defaults[index]);
285
286 // </NEW PREDICTION>
287
288 // Below, we might need to calculate the pause time target based on
289 // the pause interval. When we do so we are going to give G1 maximum
290 // flexibility and allow it to do pauses when it needs to. So, we'll
291 // arrange that the pause interval to be pause time target + 1 to
292 // ensure that a) the pause time target is maximized with respect to
293 // the pause interval and b) we maintain the invariant that pause
294 // time target < pause interval. If the user does not want this
295 // maximum flexibility, they will have to set the pause interval
296 // explicitly.
297
298 // First make sure that, if either parameter is set, its value is
299 // reasonable.
300 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
301 if (MaxGCPauseMillis < 1) {
302 vm_exit_during_initialization("MaxGCPauseMillis should be "
303 "greater than 0");
304 }
305 }
306 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
307 if (GCPauseIntervalMillis < 1) {
308 vm_exit_during_initialization("GCPauseIntervalMillis should be "
309 "greater than 0");
310 }
311 }
312
313 // Then, if the pause time target parameter was not set, set it to
314 // the default value.
315 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
316 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
317 // The default pause time target in G1 is 200ms
318 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
319 } else {
320 // We do not allow the pause interval to be set without the
321 // pause time target
322 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
323 "without setting MaxGCPauseMillis");
324 }
325 }
326
327 // Then, if the interval parameter was not set, set it according to
328 // the pause time target (this will also deal with the case when the
329 // pause time target is the default value).
330 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
331 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
332 }
333
334 // Finally, make sure that the two parameters are consistent.
335 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
336 char buffer[256];
337 jio_snprintf(buffer, 256,
338 "MaxGCPauseMillis (%u) should be less than "
339 "GCPauseIntervalMillis (%u)",
340 MaxGCPauseMillis, GCPauseIntervalMillis);
341 vm_exit_during_initialization(buffer);
342 }
343
344 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
345 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
346 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
347 _sigma = (double) G1ConfidencePercent / 100.0;
348
349 // start conservatively (around 50ms is about right)
350 _concurrent_mark_init_times_ms->add(0.05);
351 _concurrent_mark_remark_times_ms->add(0.05);
352 _concurrent_mark_cleanup_times_ms->add(0.20);
353 _tenuring_threshold = MaxTenuringThreshold;
354
355 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
356 // fixed, then _max_survivor_regions will be calculated at
357 // calculate_young_list_target_length during initialization
358 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
359
360 assert(GCTimeRatio > 0,
361 "we should have set it to a default value set_g1_gc_flags() "
362 "if a user set it to 0");
363 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
364
365 initialize_all();
366 }
367
368 // Increment "i", mod "len"
369 static void inc_mod(int& i, int len) {
370 i++; if (i == len) i = 0;
371 }
372
373 void G1CollectorPolicy::initialize_flags() {
374 set_min_alignment(HeapRegion::GrainBytes);
375 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
376 if (SurvivorRatio < 1) {
377 vm_exit_during_initialization("Invalid survivor ratio specified");
378 }
379 CollectorPolicy::initialize_flags();
380 }
381
382 // The easiest way to deal with the parsing of the NewSize /
383 // MaxNewSize / etc. parameteres is to re-use the code in the
384 // TwoGenerationCollectorPolicy class. This is similar to what
385 // ParallelScavenge does with its GenerationSizer class (see
386 // ParallelScavengeHeap::initialize()). We might change this in the
387 // future, but it's a good start.
388 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
389 size_t size_to_region_num(size_t byte_size) {
390 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
391 }
392
393 public:
394 G1YoungGenSizer() {
395 initialize_flags();
396 initialize_size_info();
397 }
398
399 size_t min_young_region_num() {
400 return size_to_region_num(_min_gen0_size);
401 }
402 size_t initial_young_region_num() {
403 return size_to_region_num(_initial_gen0_size);
404 }
405 size_t max_young_region_num() {
406 return size_to_region_num(_max_gen0_size);
407 }
408 };
409
410 void G1CollectorPolicy::init() {
411 // Set aside an initial future to_space.
412 _g1 = G1CollectedHeap::heap();
413
414 assert(Heap_lock->owned_by_self(), "Locking discipline.");
415
416 initialize_gc_policy_counters();
417
418 if (G1Gen) {
419 _in_young_gc_mode = true;
420
421 G1YoungGenSizer sizer;
422 size_t initial_region_num = sizer.initial_young_region_num();
423
424 if (UseAdaptiveSizePolicy) {
425 set_adaptive_young_list_length(true);
426 _young_list_fixed_length = 0;
427 } else {
428 set_adaptive_young_list_length(false);
429 _young_list_fixed_length = initial_region_num;
430 }
431 _free_regions_at_end_of_collection = _g1->free_regions();
432 calculate_young_list_min_length();
433 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
434 calculate_young_list_target_length();
435 } else {
436 _young_list_fixed_length = 0;
437 _in_young_gc_mode = false;
438 }
439
440 // We may immediately start allocating regions and placing them on the
441 // collection set list. Initialize the per-collection set info
442 start_incremental_cset_building();
443 }
444
445 // Create the jstat counters for the policy.
446 void G1CollectorPolicy::initialize_gc_policy_counters()
447 {
448 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
449 }
450
451 void G1CollectorPolicy::calculate_young_list_min_length() {
452 _young_list_min_length = 0;
453
454 if (!adaptive_young_list_length())
455 return;
456
457 if (_alloc_rate_ms_seq->num() > 3) {
458 double now_sec = os::elapsedTime();
459 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
460 double alloc_rate_ms = predict_alloc_rate_ms();
461 int min_regions = (int) ceil(alloc_rate_ms * when_ms);
462 int current_region_num = (int) _g1->young_list()->length();
463 _young_list_min_length = min_regions + current_region_num;
464 }
465 }
466
467 void G1CollectorPolicy::calculate_young_list_target_length() {
468 if (adaptive_young_list_length()) {
469 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
470 calculate_young_list_target_length(rs_lengths);
471 } else {
472 if (full_young_gcs())
473 _young_list_target_length = _young_list_fixed_length;
474 else
475 _young_list_target_length = _young_list_fixed_length / 2;
476
477 _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
478 }
479 calculate_survivors_policy();
480 }
481
482 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
483 guarantee( adaptive_young_list_length(), "pre-condition" );
484 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
485
486 double start_time_sec = os::elapsedTime();
487 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
488 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
489 size_t reserve_regions =
490 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
491
492 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
493 // we are in fully-young mode and there are free regions in the heap
494
495 double survivor_regions_evac_time =
496 predict_survivor_regions_evac_time();
497
498 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
499 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
500 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
501 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
502 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
503 + survivor_regions_evac_time;
504
505 // the result
506 size_t final_young_length = 0;
507
508 size_t init_free_regions =
509 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
510
511 // if we're still under the pause target...
512 if (base_time_ms <= target_pause_time_ms) {
513 // We make sure that the shortest young length that makes sense
514 // fits within the target pause time.
515 size_t min_young_length = 1;
516
517 if (predict_will_fit(min_young_length, base_time_ms,
518 init_free_regions, target_pause_time_ms)) {
519 // The shortest young length will fit within the target pause time;
520 // we'll now check whether the absolute maximum number of young
521 // regions will fit in the target pause time. If not, we'll do
522 // a binary search between min_young_length and max_young_length
523 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
524 size_t max_young_length = abs_max_young_length;
525
526 if (max_young_length > min_young_length) {
527 // Let's check if the initial max young length will fit within the
528 // target pause. If so then there is no need to search for a maximal
529 // young length - we'll return the initial maximum
530
531 if (predict_will_fit(max_young_length, base_time_ms,
532 init_free_regions, target_pause_time_ms)) {
533 // The maximum young length will satisfy the target pause time.
534 // We are done so set min young length to this maximum length.
535 // The code after the loop will then set final_young_length using
536 // the value cached in the minimum length.
537 min_young_length = max_young_length;
538 } else {
539 // The maximum possible number of young regions will not fit within
540 // the target pause time so let's search....
541
542 size_t diff = (max_young_length - min_young_length) / 2;
543 max_young_length = min_young_length + diff;
544
545 while (max_young_length > min_young_length) {
546 if (predict_will_fit(max_young_length, base_time_ms,
547 init_free_regions, target_pause_time_ms)) {
548
549 // The current max young length will fit within the target
550 // pause time. Note we do not exit the loop here. By setting
551 // min = max, and then increasing the max below means that
552 // we will continue searching for an upper bound in the
553 // range [max..max+diff]
554 min_young_length = max_young_length;
555 }
556 diff = (max_young_length - min_young_length) / 2;
557 max_young_length = min_young_length + diff;
558 }
559 // the above loop found a maximal young length that will fit
560 // within the target pause time.
561 }
562 assert(min_young_length <= abs_max_young_length, "just checking");
563 }
564 final_young_length = min_young_length;
565 }
566 }
567 // and we're done!
568
569 // we should have at least one region in the target young length
570 _young_list_target_length =
571 MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
572
573 // let's keep an eye of how long we spend on this calculation
574 // right now, I assume that we'll print it when we need it; we
575 // should really adde it to the breakdown of a pause
576 double end_time_sec = os::elapsedTime();
577 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
578
579 #ifdef TRACE_CALC_YOUNG_LENGTH
580 // leave this in for debugging, just in case
581 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
582 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
583 target_pause_time_ms,
584 _young_list_target_length
585 elapsed_time_ms,
586 full_young_gcs() ? "full" : "partial",
587 during_initial_mark_pause() ? " i-m" : "",
588 _in_marking_window,
589 _in_marking_window_im);
590 #endif // TRACE_CALC_YOUNG_LENGTH
591
592 if (_young_list_target_length < _young_list_min_length) {
593 // bummer; this means that, if we do a pause when the maximal
594 // length dictates, we'll violate the pause spacing target (the
595 // min length was calculate based on the application's current
596 // alloc rate);
597
598 // so, we have to bite the bullet, and allocate the minimum
599 // number. We'll violate our target, but we just can't meet it.
600
601 #ifdef TRACE_CALC_YOUNG_LENGTH
602 // leave this in for debugging, just in case
603 gclog_or_tty->print_cr("adjusted target length from "
604 SIZE_FORMAT " to " SIZE_FORMAT,
605 _young_list_target_length, _young_list_min_length);
606 #endif // TRACE_CALC_YOUNG_LENGTH
607
608 _young_list_target_length = _young_list_min_length;
609 }
610 } else {
611 // we are in a partially-young mode or we've run out of regions (due
612 // to evacuation failure)
613
614 #ifdef TRACE_CALC_YOUNG_LENGTH
615 // leave this in for debugging, just in case
616 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
617 _young_list_min_length);
618 #endif // TRACE_CALC_YOUNG_LENGTH
619 // we'll do the pause as soon as possible by choosing the minimum
620 _young_list_target_length =
621 MAX2(_young_list_min_length, (size_t) 1);
622 }
623
624 _rs_lengths_prediction = rs_lengths;
625 }
626
627 // This is used by: calculate_young_list_target_length(rs_length). It
628 // returns true iff:
629 // the predicted pause time for the given young list will not overflow
630 // the target pause time
631 // and:
632 // the predicted amount of surviving data will not overflow the
633 // the amount of free space available for survivor regions.
634 //
635 bool
636 G1CollectorPolicy::predict_will_fit(size_t young_length,
637 double base_time_ms,
638 size_t init_free_regions,
639 double target_pause_time_ms) {
640
641 if (young_length >= init_free_regions)
642 // end condition 1: not enough space for the young regions
643 return false;
644
645 double accum_surv_rate_adj = 0.0;
646 double accum_surv_rate =
647 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
648
649 size_t bytes_to_copy =
650 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
651
652 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
653
654 double young_other_time_ms =
655 predict_young_other_time_ms(young_length);
656
657 double pause_time_ms =
658 base_time_ms + copy_time_ms + young_other_time_ms;
659
660 if (pause_time_ms > target_pause_time_ms)
661 // end condition 2: over the target pause time
662 return false;
663
664 size_t free_bytes =
665 (init_free_regions - young_length) * HeapRegion::GrainBytes;
666
667 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
668 // end condition 3: out of to-space (conservatively)
669 return false;
670
671 // success!
672 return true;
673 }
674
675 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
676 double survivor_regions_evac_time = 0.0;
677 for (HeapRegion * r = _recorded_survivor_head;
678 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
679 r = r->get_next_young_region()) {
680 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
681 }
682 return survivor_regions_evac_time;
683 }
684
685 void G1CollectorPolicy::check_prediction_validity() {
686 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
687
688 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
689 if (rs_lengths > _rs_lengths_prediction) {
690 // add 10% to avoid having to recalculate often
691 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
692 calculate_young_list_target_length(rs_lengths_prediction);
693 }
694 }
695
696 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
697 bool is_tlab,
698 bool* gc_overhead_limit_was_exceeded) {
699 guarantee(false, "Not using this policy feature yet.");
700 return NULL;
701 }
702
703 // This method controls how a collector handles one or more
704 // of its generations being fully allocated.
705 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
706 bool is_tlab) {
707 guarantee(false, "Not using this policy feature yet.");
708 return NULL;
709 }
710
711
712 #ifndef PRODUCT
713 bool G1CollectorPolicy::verify_young_ages() {
714 HeapRegion* head = _g1->young_list()->first_region();
715 return
716 verify_young_ages(head, _short_lived_surv_rate_group);
717 // also call verify_young_ages on any additional surv rate groups
718 }
719
720 bool
721 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
722 SurvRateGroup *surv_rate_group) {
723 guarantee( surv_rate_group != NULL, "pre-condition" );
724
725 const char* name = surv_rate_group->name();
726 bool ret = true;
727 int prev_age = -1;
728
729 for (HeapRegion* curr = head;
730 curr != NULL;
731 curr = curr->get_next_young_region()) {
732 SurvRateGroup* group = curr->surv_rate_group();
733 if (group == NULL && !curr->is_survivor()) {
734 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
735 ret = false;
736 }
737
738 if (surv_rate_group == group) {
739 int age = curr->age_in_surv_rate_group();
740
741 if (age < 0) {
742 gclog_or_tty->print_cr("## %s: encountered negative age", name);
743 ret = false;
744 }
745
746 if (age <= prev_age) {
747 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
748 "(%d, %d)", name, age, prev_age);
749 ret = false;
750 }
751 prev_age = age;
752 }
753 }
754
755 return ret;
756 }
757 #endif // PRODUCT
758
759 void G1CollectorPolicy::record_full_collection_start() {
760 _cur_collection_start_sec = os::elapsedTime();
761 // Release the future to-space so that it is available for compaction into.
762 _g1->set_full_collection();
763 }
764
765 void G1CollectorPolicy::record_full_collection_end() {
766 // Consider this like a collection pause for the purposes of allocation
767 // since last pause.
768 double end_sec = os::elapsedTime();
769 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
770 double full_gc_time_ms = full_gc_time_sec * 1000.0;
771
772 _all_full_gc_times_ms->add(full_gc_time_ms);
773
774 update_recent_gc_times(end_sec, full_gc_time_ms);
775
776 _g1->clear_full_collection();
777
778 // "Nuke" the heuristics that control the fully/partially young GC
779 // transitions and make sure we start with fully young GCs after the
780 // Full GC.
781 set_full_young_gcs(true);
782 _last_full_young_gc = false;
783 _should_revert_to_full_young_gcs = false;
784 clear_initiate_conc_mark_if_possible();
785 clear_during_initial_mark_pause();
786 _known_garbage_bytes = 0;
787 _known_garbage_ratio = 0.0;
788 _in_marking_window = false;
789 _in_marking_window_im = false;
790
791 _short_lived_surv_rate_group->start_adding_regions();
792 // also call this on any additional surv rate groups
793
794 record_survivor_regions(0, NULL, NULL);
795
796 _prev_region_num_young = _region_num_young;
797 _prev_region_num_tenured = _region_num_tenured;
798
799 _free_regions_at_end_of_collection = _g1->free_regions();
800 // Reset survivors SurvRateGroup.
801 _survivor_surv_rate_group->reset();
802 calculate_young_list_min_length();
803 calculate_young_list_target_length();
804 }
805
806 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
807 _bytes_in_to_space_before_gc += bytes;
808 }
809
810 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
811 _bytes_in_to_space_after_gc += bytes;
812 }
813
814 void G1CollectorPolicy::record_stop_world_start() {
815 _stop_world_start = os::elapsedTime();
816 }
817
818 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
819 size_t start_used) {
820 if (PrintGCDetails) {
821 gclog_or_tty->stamp(PrintGCTimeStamps);
822 gclog_or_tty->print("[GC pause");
823 if (in_young_gc_mode())
824 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
825 }
826
827 assert(_g1->used_regions() == _g1->recalculate_used_regions(),
828 "sanity");
829 assert(_g1->used() == _g1->recalculate_used(), "sanity");
830
831 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
832 _all_stop_world_times_ms->add(s_w_t_ms);
833 _stop_world_start = 0.0;
834
835 _cur_collection_start_sec = start_time_sec;
836 _cur_collection_pause_used_at_start_bytes = start_used;
837 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
838 _pending_cards = _g1->pending_card_num();
839 _max_pending_cards = _g1->max_pending_card_num();
840
841 _bytes_in_to_space_before_gc = 0;
842 _bytes_in_to_space_after_gc = 0;
843 _bytes_in_collection_set_before_gc = 0;
844
845 #ifdef DEBUG
846 // initialise these to something well known so that we can spot
847 // if they are not set properly
848
849 for (int i = 0; i < _parallel_gc_threads; ++i) {
850 _par_last_gc_worker_start_times_ms[i] = -1234.0;
851 _par_last_ext_root_scan_times_ms[i] = -1234.0;
852 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
853 _par_last_update_rs_times_ms[i] = -1234.0;
854 _par_last_update_rs_processed_buffers[i] = -1234.0;
855 _par_last_scan_rs_times_ms[i] = -1234.0;
856 _par_last_obj_copy_times_ms[i] = -1234.0;
857 _par_last_termination_times_ms[i] = -1234.0;
858 _par_last_termination_attempts[i] = -1234.0;
859 _par_last_gc_worker_end_times_ms[i] = -1234.0;
860 }
861 #endif
862
863 for (int i = 0; i < _aux_num; ++i) {
864 _cur_aux_times_ms[i] = 0.0;
865 _cur_aux_times_set[i] = false;
866 }
867
868 _satb_drain_time_set = false;
869 _last_satb_drain_processed_buffers = -1;
870
871 if (in_young_gc_mode())
872 _last_young_gc_full = false;
873
874 // do that for any other surv rate groups
875 _short_lived_surv_rate_group->stop_adding_regions();
876 _survivors_age_table.clear();
877
878 assert( verify_young_ages(), "region age verification" );
879 }
880
881 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
882 _mark_closure_time_ms = mark_closure_time_ms;
883 }
884
885 void G1CollectorPolicy::record_concurrent_mark_init_start() {
886 _mark_init_start_sec = os::elapsedTime();
887 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
888 }
889
890 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
891 mark_init_elapsed_time_ms) {
892 _during_marking = true;
893 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
894 clear_during_initial_mark_pause();
895 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
896 }
897
898 void G1CollectorPolicy::record_concurrent_mark_init_end() {
899 double end_time_sec = os::elapsedTime();
900 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
901 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
902 record_concurrent_mark_init_end_pre(elapsed_time_ms);
903
904 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
905 }
906
907 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
908 _mark_remark_start_sec = os::elapsedTime();
909 _during_marking = false;
910 }
911
912 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
913 double end_time_sec = os::elapsedTime();
914 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
915 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
916 _cur_mark_stop_world_time_ms += elapsed_time_ms;
917 _prev_collection_pause_end_ms += elapsed_time_ms;
918
919 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
920 }
921
922 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
923 _mark_cleanup_start_sec = os::elapsedTime();
924 }
925
926 void
927 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
928 size_t max_live_bytes) {
929 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
930 record_concurrent_mark_cleanup_end_work2();
931 }
932
933 void
934 G1CollectorPolicy::
935 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
936 size_t max_live_bytes) {
937 if (_n_marks < 2) _n_marks++;
938 if (G1PolicyVerbose > 0)
939 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
940 " (of " SIZE_FORMAT " MB heap).",
941 max_live_bytes/M, _g1->capacity()/M);
942 }
943
944 // The important thing about this is that it includes "os::elapsedTime".
945 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
946 double end_time_sec = os::elapsedTime();
947 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
948 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
949 _cur_mark_stop_world_time_ms += elapsed_time_ms;
950 _prev_collection_pause_end_ms += elapsed_time_ms;
951
952 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
953
954 _num_markings++;
955
956 // We did a marking, so reset the "since_last_mark" variables.
957 double considerConcMarkCost = 1.0;
958 // If there are available processors, concurrent activity is free...
959 if (Threads::number_of_non_daemon_threads() * 2 <
960 os::active_processor_count()) {
961 considerConcMarkCost = 0.0;
962 }
963 _n_pauses_at_mark_end = _n_pauses;
964 _n_marks_since_last_pause++;
965 }
966
967 void
968 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
969 if (in_young_gc_mode()) {
970 _should_revert_to_full_young_gcs = false;
971 _last_full_young_gc = true;
972 _in_marking_window = false;
973 if (adaptive_young_list_length())
974 calculate_young_list_target_length();
975 }
976 }
977
978 void G1CollectorPolicy::record_concurrent_pause() {
979 if (_stop_world_start > 0.0) {
980 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
981 _all_yield_times_ms->add(yield_ms);
982 }
983 }
984
985 void G1CollectorPolicy::record_concurrent_pause_end() {
986 }
987
988 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
989 _cur_CH_strong_roots_end_sec = os::elapsedTime();
990 _cur_CH_strong_roots_dur_ms =
991 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
992 }
993
994 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
995 _cur_G1_strong_roots_end_sec = os::elapsedTime();
996 _cur_G1_strong_roots_dur_ms =
997 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
998 }
999
1000 template<class T>
1001 T sum_of(T* sum_arr, int start, int n, int N) {
1002 T sum = (T)0;
1003 for (int i = 0; i < n; i++) {
1004 int j = (start + i) % N;
1005 sum += sum_arr[j];
1006 }
1007 return sum;
1008 }
1009
1010 void G1CollectorPolicy::print_par_stats(int level,
1011 const char* str,
1012 double* data,
1013 bool summary) {
1014 double min = data[0], max = data[0];
1015 double total = 0.0;
1016 int j;
1017 for (j = 0; j < level; ++j)
1018 gclog_or_tty->print(" ");
1019 gclog_or_tty->print("[%s (ms):", str);
1020 for (uint i = 0; i < ParallelGCThreads; ++i) {
1021 double val = data[i];
1022 if (val < min)
1023 min = val;
1024 if (val > max)
1025 max = val;
1026 total += val;
1027 gclog_or_tty->print(" %3.1lf", val);
1028 }
1029 if (summary) {
1030 gclog_or_tty->print_cr("");
1031 double avg = total / (double) ParallelGCThreads;
1032 gclog_or_tty->print(" ");
1033 for (j = 0; j < level; ++j)
1034 gclog_or_tty->print(" ");
1035 gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
1036 avg, min, max);
1037 }
1038 gclog_or_tty->print_cr("]");
1039 }
1040
1041 void G1CollectorPolicy::print_par_sizes(int level,
1042 const char* str,
1043 double* data,
1044 bool summary) {
1045 double min = data[0], max = data[0];
1046 double total = 0.0;
1047 int j;
1048 for (j = 0; j < level; ++j)
1049 gclog_or_tty->print(" ");
1050 gclog_or_tty->print("[%s :", str);
1051 for (uint i = 0; i < ParallelGCThreads; ++i) {
1052 double val = data[i];
1053 if (val < min)
1054 min = val;
1055 if (val > max)
1056 max = val;
1057 total += val;
1058 gclog_or_tty->print(" %d", (int) val);
1059 }
1060 if (summary) {
1061 gclog_or_tty->print_cr("");
1062 double avg = total / (double) ParallelGCThreads;
1063 gclog_or_tty->print(" ");
1064 for (j = 0; j < level; ++j)
1065 gclog_or_tty->print(" ");
1066 gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
1067 (int)total, (int)avg, (int)min, (int)max);
1068 }
1069 gclog_or_tty->print_cr("]");
1070 }
1071
1072 void G1CollectorPolicy::print_stats (int level,
1073 const char* str,
1074 double value) {
1075 for (int j = 0; j < level; ++j)
1076 gclog_or_tty->print(" ");
1077 gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
1078 }
1079
1080 void G1CollectorPolicy::print_stats (int level,
1081 const char* str,
1082 int value) {
1083 for (int j = 0; j < level; ++j)
1084 gclog_or_tty->print(" ");
1085 gclog_or_tty->print_cr("[%s: %d]", str, value);
1086 }
1087
1088 double G1CollectorPolicy::avg_value (double* data) {
1089 if (G1CollectedHeap::use_parallel_gc_threads()) {
1090 double ret = 0.0;
1091 for (uint i = 0; i < ParallelGCThreads; ++i)
1092 ret += data[i];
1093 return ret / (double) ParallelGCThreads;
1094 } else {
1095 return data[0];
1096 }
1097 }
1098
1099 double G1CollectorPolicy::max_value (double* data) {
1100 if (G1CollectedHeap::use_parallel_gc_threads()) {
1101 double ret = data[0];
1102 for (uint i = 1; i < ParallelGCThreads; ++i)
1103 if (data[i] > ret)
1104 ret = data[i];
1105 return ret;
1106 } else {
1107 return data[0];
1108 }
1109 }
1110
1111 double G1CollectorPolicy::sum_of_values (double* data) {
1112 if (G1CollectedHeap::use_parallel_gc_threads()) {
1113 double sum = 0.0;
1114 for (uint i = 0; i < ParallelGCThreads; i++)
1115 sum += data[i];
1116 return sum;
1117 } else {
1118 return data[0];
1119 }
1120 }
1121
1122 double G1CollectorPolicy::max_sum (double* data1,
1123 double* data2) {
1124 double ret = data1[0] + data2[0];
1125
1126 if (G1CollectedHeap::use_parallel_gc_threads()) {
1127 for (uint i = 1; i < ParallelGCThreads; ++i) {
1128 double data = data1[i] + data2[i];
1129 if (data > ret)
1130 ret = data;
1131 }
1132 }
1133 return ret;
1134 }
1135
1136 // Anything below that is considered to be zero
1137 #define MIN_TIMER_GRANULARITY 0.0000001
1138
1139 void G1CollectorPolicy::record_collection_pause_end() {
1140 double end_time_sec = os::elapsedTime();
1141 double elapsed_ms = _last_pause_time_ms;
1142 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1143 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1144 size_t rs_size =
1145 _cur_collection_pause_used_regions_at_start - collection_set_size();
1146 size_t cur_used_bytes = _g1->used();
1147 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1148 bool last_pause_included_initial_mark = false;
1149 bool update_stats = !_g1->evacuation_failed();
1150
1151 #ifndef PRODUCT
1152 if (G1YoungSurvRateVerbose) {
1153 gclog_or_tty->print_cr("");
1154 _short_lived_surv_rate_group->print();
1155 // do that for any other surv rate groups too
1156 }
1157 #endif // PRODUCT
1158
1159 if (in_young_gc_mode()) {
1160 last_pause_included_initial_mark = during_initial_mark_pause();
1161 if (last_pause_included_initial_mark)
1162 record_concurrent_mark_init_end_pre(0.0);
1163
1164 size_t min_used_targ =
1165 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1166
1167
1168 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1169 assert(!last_pause_included_initial_mark, "invariant");
1170 if (cur_used_bytes > min_used_targ &&
1171 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1172 assert(!during_initial_mark_pause(), "we should not see this here");
1173
1174 // Note: this might have already been set, if during the last
1175 // pause we decided to start a cycle but at the beginning of
1176 // this pause we decided to postpone it. That's OK.
1177 set_initiate_conc_mark_if_possible();
1178 }
1179 }
1180
1181 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1182 }
1183
1184 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1185 end_time_sec, false);
1186
1187 guarantee(_cur_collection_pause_used_regions_at_start >=
1188 collection_set_size(),
1189 "Negative RS size?");
1190
1191 // This assert is exempted when we're doing parallel collection pauses,
1192 // because the fragmentation caused by the parallel GC allocation buffers
1193 // can lead to more memory being used during collection than was used
1194 // before. Best leave this out until the fragmentation problem is fixed.
1195 // Pauses in which evacuation failed can also lead to negative
1196 // collections, since no space is reclaimed from a region containing an
1197 // object whose evacuation failed.
1198 // Further, we're now always doing parallel collection. But I'm still
1199 // leaving this here as a placeholder for a more precise assertion later.
1200 // (DLD, 10/05.)
1201 assert((true || parallel) // Always using GC LABs now.
1202 || _g1->evacuation_failed()
1203 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1204 "Negative collection");
1205
1206 size_t freed_bytes =
1207 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1208 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1209
1210 double survival_fraction =
1211 (double)surviving_bytes/
1212 (double)_collection_set_bytes_used_before;
1213
1214 _n_pauses++;
1215
1216 if (update_stats) {
1217 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1218 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1219 _recent_evac_times_ms->add(evac_ms);
1220 _recent_pause_times_ms->add(elapsed_ms);
1221
1222 _recent_rs_sizes->add(rs_size);
1223
1224 // We exempt parallel collection from this check because Alloc Buffer
1225 // fragmentation can produce negative collections. Same with evac
1226 // failure.
1227 // Further, we're now always doing parallel collection. But I'm still
1228 // leaving this here as a placeholder for a more precise assertion later.
1229 // (DLD, 10/05.
1230 assert((true || parallel)
1231 || _g1->evacuation_failed()
1232 || surviving_bytes <= _collection_set_bytes_used_before,
1233 "Or else negative collection!");
1234 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1235 _recent_CS_bytes_surviving->add(surviving_bytes);
1236
1237 // this is where we update the allocation rate of the application
1238 double app_time_ms =
1239 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1240 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1241 // This usually happens due to the timer not having the required
1242 // granularity. Some Linuxes are the usual culprits.
1243 // We'll just set it to something (arbitrarily) small.
1244 app_time_ms = 1.0;
1245 }
1246 size_t regions_allocated =
1247 (_region_num_young - _prev_region_num_young) +
1248 (_region_num_tenured - _prev_region_num_tenured);
1249 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1250 _alloc_rate_ms_seq->add(alloc_rate_ms);
1251 _prev_region_num_young = _region_num_young;
1252 _prev_region_num_tenured = _region_num_tenured;
1253
1254 double interval_ms =
1255 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1256 update_recent_gc_times(end_time_sec, elapsed_ms);
1257 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1258 if (recent_avg_pause_time_ratio() < 0.0 ||
1259 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1260 #ifndef PRODUCT
1261 // Dump info to allow post-facto debugging
1262 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1263 gclog_or_tty->print_cr("-------------------------------------------");
1264 gclog_or_tty->print_cr("Recent GC Times (ms):");
1265 _recent_gc_times_ms->dump();
1266 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1267 _recent_prev_end_times_for_all_gcs_sec->dump();
1268 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1269 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1270 // In debug mode, terminate the JVM if the user wants to debug at this point.
1271 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1272 #endif // !PRODUCT
1273 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1274 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1275 if (_recent_avg_pause_time_ratio < 0.0) {
1276 _recent_avg_pause_time_ratio = 0.0;
1277 } else {
1278 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1279 _recent_avg_pause_time_ratio = 1.0;
1280 }
1281 }
1282 }
1283
1284 if (G1PolicyVerbose > 1) {
1285 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1286 }
1287
1288 PauseSummary* summary = _summary;
1289
1290 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1291 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1292 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1293 double update_rs_processed_buffers =
1294 sum_of_values(_par_last_update_rs_processed_buffers);
1295 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1296 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1297 double termination_time = avg_value(_par_last_termination_times_ms);
1298
1299 double parallel_other_time = _cur_collection_par_time_ms -
1300 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1301 scan_rs_time + obj_copy_time + termination_time);
1302 if (update_stats) {
1303 MainBodySummary* body_summary = summary->main_body_summary();
1304 guarantee(body_summary != NULL, "should not be null!");
1305
1306 if (_satb_drain_time_set)
1307 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1308 else
1309 body_summary->record_satb_drain_time_ms(0.0);
1310 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1311 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1312 body_summary->record_update_rs_time_ms(update_rs_time);
1313 body_summary->record_scan_rs_time_ms(scan_rs_time);
1314 body_summary->record_obj_copy_time_ms(obj_copy_time);
1315 if (parallel) {
1316 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1317 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1318 body_summary->record_termination_time_ms(termination_time);
1319 body_summary->record_parallel_other_time_ms(parallel_other_time);
1320 }
1321 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1322 }
1323
1324 if (G1PolicyVerbose > 1) {
1325 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1326 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1327 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1328 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1329 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1330 " |RS|: " SIZE_FORMAT,
1331 elapsed_ms, recent_avg_time_for_pauses_ms(),
1332 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1333 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1334 evac_ms, recent_avg_time_for_evac_ms(),
1335 scan_rs_time,
1336 recent_avg_time_for_pauses_ms() -
1337 recent_avg_time_for_G1_strong_ms(),
1338 rs_size);
1339
1340 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1341 " At end " SIZE_FORMAT "K\n"
1342 " garbage : " SIZE_FORMAT "K"
1343 " of " SIZE_FORMAT "K\n"
1344 " survival : %6.2f%% (%6.2f%% avg)",
1345 _cur_collection_pause_used_at_start_bytes/K,
1346 _g1->used()/K, freed_bytes/K,
1347 _collection_set_bytes_used_before/K,
1348 survival_fraction*100.0,
1349 recent_avg_survival_fraction()*100.0);
1350 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1351 recent_avg_pause_time_ratio() * 100.0);
1352 }
1353
1354 double other_time_ms = elapsed_ms;
1355
1356 if (_satb_drain_time_set) {
1357 other_time_ms -= _cur_satb_drain_time_ms;
1358 }
1359
1360 if (parallel) {
1361 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1362 } else {
1363 other_time_ms -=
1364 update_rs_time +
1365 ext_root_scan_time + mark_stack_scan_time +
1366 scan_rs_time + obj_copy_time;
1367 }
1368
1369 if (PrintGCDetails) {
1370 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1371 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1372 elapsed_ms / 1000.0);
1373
1374 if (_satb_drain_time_set) {
1375 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1376 }
1377 if (_last_satb_drain_processed_buffers >= 0) {
1378 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1379 }
1380 if (parallel) {
1381 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1382 print_par_stats(2, "GC Worker Start Time",
1383 _par_last_gc_worker_start_times_ms, false);
1384 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1385 print_par_sizes(3, "Processed Buffers",
1386 _par_last_update_rs_processed_buffers, true);
1387 print_par_stats(2, "Ext Root Scanning",
1388 _par_last_ext_root_scan_times_ms);
1389 print_par_stats(2, "Mark Stack Scanning",
1390 _par_last_mark_stack_scan_times_ms);
1391 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1392 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1393 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1394 print_par_sizes(3, "Termination Attempts",
1395 _par_last_termination_attempts, true);
1396 print_par_stats(2, "GC Worker End Time",
1397 _par_last_gc_worker_end_times_ms, false);
1398 print_stats(2, "Other", parallel_other_time);
1399 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1400 } else {
1401 print_stats(1, "Update RS", update_rs_time);
1402 print_stats(2, "Processed Buffers",
1403 (int)update_rs_processed_buffers);
1404 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1405 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1406 print_stats(1, "Scan RS", scan_rs_time);
1407 print_stats(1, "Object Copying", obj_copy_time);
1408 }
1409 #ifndef PRODUCT
1410 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1411 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1412 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1413 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1414 if (_num_cc_clears > 0) {
1415 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1416 }
1417 #endif
1418 print_stats(1, "Other", other_time_ms);
1419 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1420
1421 for (int i = 0; i < _aux_num; ++i) {
1422 if (_cur_aux_times_set[i]) {
1423 char buffer[96];
1424 sprintf(buffer, "Aux%d", i);
1425 print_stats(1, buffer, _cur_aux_times_ms[i]);
1426 }
1427 }
1428 }
1429 if (PrintGCDetails)
1430 gclog_or_tty->print(" [");
1431 if (PrintGC || PrintGCDetails)
1432 _g1->print_size_transition(gclog_or_tty,
1433 _cur_collection_pause_used_at_start_bytes,
1434 _g1->used(), _g1->capacity());
1435 if (PrintGCDetails)
1436 gclog_or_tty->print_cr("]");
1437
1438 _all_pause_times_ms->add(elapsed_ms);
1439 if (update_stats) {
1440 summary->record_total_time_ms(elapsed_ms);
1441 summary->record_other_time_ms(other_time_ms);
1442 }
1443 for (int i = 0; i < _aux_num; ++i)
1444 if (_cur_aux_times_set[i])
1445 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1446
1447 // Reset marks-between-pauses counter.
1448 _n_marks_since_last_pause = 0;
1449
1450 // Update the efficiency-since-mark vars.
1451 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1452 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1453 // This usually happens due to the timer not having the required
1454 // granularity. Some Linuxes are the usual culprits.
1455 // We'll just set it to something (arbitrarily) small.
1456 proc_ms = 1.0;
1457 }
1458 double cur_efficiency = (double) freed_bytes / proc_ms;
1459
1460 bool new_in_marking_window = _in_marking_window;
1461 bool new_in_marking_window_im = false;
1462 if (during_initial_mark_pause()) {
1463 new_in_marking_window = true;
1464 new_in_marking_window_im = true;
1465 }
1466
1467 if (in_young_gc_mode()) {
1468 if (_last_full_young_gc) {
1469 set_full_young_gcs(false);
1470 _last_full_young_gc = false;
1471 }
1472
1473 if ( !_last_young_gc_full ) {
1474 if ( _should_revert_to_full_young_gcs ||
1475 _known_garbage_ratio < 0.05 ||
1476 (adaptive_young_list_length() &&
1477 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1478 set_full_young_gcs(true);
1479 }
1480 }
1481 _should_revert_to_full_young_gcs = false;
1482
1483 if (_last_young_gc_full && !_during_marking)
1484 _young_gc_eff_seq->add(cur_efficiency);
1485 }
1486
1487 _short_lived_surv_rate_group->start_adding_regions();
1488 // do that for any other surv rate groupsx
1489
1490 // <NEW PREDICTION>
1491
1492 if (update_stats) {
1493 double pause_time_ms = elapsed_ms;
1494
1495 size_t diff = 0;
1496 if (_max_pending_cards >= _pending_cards)
1497 diff = _max_pending_cards - _pending_cards;
1498 _pending_card_diff_seq->add((double) diff);
1499
1500 double cost_per_card_ms = 0.0;
1501 if (_pending_cards > 0) {
1502 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1503 _cost_per_card_ms_seq->add(cost_per_card_ms);
1504 }
1505
1506 size_t cards_scanned = _g1->cards_scanned();
1507
1508 double cost_per_entry_ms = 0.0;
1509 if (cards_scanned > 10) {
1510 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1511 if (_last_young_gc_full)
1512 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1513 else
1514 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1515 }
1516
1517 if (_max_rs_lengths > 0) {
1518 double cards_per_entry_ratio =
1519 (double) cards_scanned / (double) _max_rs_lengths;
1520 if (_last_young_gc_full)
1521 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1522 else
1523 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1524 }
1525
1526 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1527 if (rs_length_diff >= 0)
1528 _rs_length_diff_seq->add((double) rs_length_diff);
1529
1530 size_t copied_bytes = surviving_bytes;
1531 double cost_per_byte_ms = 0.0;
1532 if (copied_bytes > 0) {
1533 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1534 if (_in_marking_window)
1535 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1536 else
1537 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1538 }
1539
1540 double all_other_time_ms = pause_time_ms -
1541 (update_rs_time + scan_rs_time + obj_copy_time +
1542 _mark_closure_time_ms + termination_time);
1543
1544 double young_other_time_ms = 0.0;
1545 if (_recorded_young_regions > 0) {
1546 young_other_time_ms =
1547 _recorded_young_cset_choice_time_ms +
1548 _recorded_young_free_cset_time_ms;
1549 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1550 (double) _recorded_young_regions);
1551 }
1552 double non_young_other_time_ms = 0.0;
1553 if (_recorded_non_young_regions > 0) {
1554 non_young_other_time_ms =
1555 _recorded_non_young_cset_choice_time_ms +
1556 _recorded_non_young_free_cset_time_ms;
1557
1558 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1559 (double) _recorded_non_young_regions);
1560 }
1561
1562 double constant_other_time_ms = all_other_time_ms -
1563 (young_other_time_ms + non_young_other_time_ms);
1564 _constant_other_time_ms_seq->add(constant_other_time_ms);
1565
1566 double survival_ratio = 0.0;
1567 if (_bytes_in_collection_set_before_gc > 0) {
1568 survival_ratio = (double) bytes_in_to_space_during_gc() /
1569 (double) _bytes_in_collection_set_before_gc;
1570 }
1571
1572 _pending_cards_seq->add((double) _pending_cards);
1573 _scanned_cards_seq->add((double) cards_scanned);
1574 _rs_lengths_seq->add((double) _max_rs_lengths);
1575
1576 double expensive_region_limit_ms =
1577 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1578 if (expensive_region_limit_ms < 0.0) {
1579 // this means that the other time was predicted to be longer than
1580 // than the max pause time
1581 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1582 }
1583 _expensive_region_limit_ms = expensive_region_limit_ms;
1584
1585 if (PREDICTIONS_VERBOSE) {
1586 gclog_or_tty->print_cr("");
1587 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1588 "REGIONS %d %d %d "
1589 "PENDING_CARDS %d %d "
1590 "CARDS_SCANNED %d %d "
1591 "RS_LENGTHS %d %d "
1592 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1593 "SURVIVAL_RATIO %1.6lf %1.6lf "
1594 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1595 "OTHER_YOUNG %1.6lf %1.6lf "
1596 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1597 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1598 "ELAPSED %1.6lf %1.6lf ",
1599 _cur_collection_start_sec,
1600 (!_last_young_gc_full) ? 2 :
1601 (last_pause_included_initial_mark) ? 1 : 0,
1602 _recorded_region_num,
1603 _recorded_young_regions,
1604 _recorded_non_young_regions,
1605 _predicted_pending_cards, _pending_cards,
1606 _predicted_cards_scanned, cards_scanned,
1607 _predicted_rs_lengths, _max_rs_lengths,
1608 _predicted_rs_update_time_ms, update_rs_time,
1609 _predicted_rs_scan_time_ms, scan_rs_time,
1610 _predicted_survival_ratio, survival_ratio,
1611 _predicted_object_copy_time_ms, obj_copy_time,
1612 _predicted_constant_other_time_ms, constant_other_time_ms,
1613 _predicted_young_other_time_ms, young_other_time_ms,
1614 _predicted_non_young_other_time_ms,
1615 non_young_other_time_ms,
1616 _vtime_diff_ms, termination_time,
1617 _predicted_pause_time_ms, elapsed_ms);
1618 }
1619
1620 if (G1PolicyVerbose > 0) {
1621 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1622 _predicted_pause_time_ms,
1623 (_within_target) ? "within" : "outside",
1624 elapsed_ms);
1625 }
1626
1627 }
1628
1629 _in_marking_window = new_in_marking_window;
1630 _in_marking_window_im = new_in_marking_window_im;
1631 _free_regions_at_end_of_collection = _g1->free_regions();
1632 calculate_young_list_min_length();
1633 calculate_young_list_target_length();
1634
1635 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1636 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1637 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1638 // </NEW PREDICTION>
1639 }
1640
1641 // <NEW PREDICTION>
1642
1643 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1644 double update_rs_processed_buffers,
1645 double goal_ms) {
1646 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1647 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1648
1649 if (G1UseAdaptiveConcRefinement) {
1650 const int k_gy = 3, k_gr = 6;
1651 const double inc_k = 1.1, dec_k = 0.9;
1652
1653 int g = cg1r->green_zone();
1654 if (update_rs_time > goal_ms) {
1655 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1656 } else {
1657 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1658 g = (int)MAX2(g * inc_k, g + 1.0);
1659 }
1660 }
1661 // Change the refinement threads params
1662 cg1r->set_green_zone(g);
1663 cg1r->set_yellow_zone(g * k_gy);
1664 cg1r->set_red_zone(g * k_gr);
1665 cg1r->reinitialize_threads();
1666
1667 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1668 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1669 cg1r->yellow_zone());
1670 // Change the barrier params
1671 dcqs.set_process_completed_threshold(processing_threshold);
1672 dcqs.set_max_completed_queue(cg1r->red_zone());
1673 }
1674
1675 int curr_queue_size = dcqs.completed_buffers_num();
1676 if (curr_queue_size >= cg1r->yellow_zone()) {
1677 dcqs.set_completed_queue_padding(curr_queue_size);
1678 } else {
1679 dcqs.set_completed_queue_padding(0);
1680 }
1681 dcqs.notify_if_necessary();
1682 }
1683
1684 double
1685 G1CollectorPolicy::
1686 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1687 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1688
1689 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1690 size_t young_num = g1h->young_list()->length();
1691 if (young_num == 0)
1692 return 0.0;
1693
1694 young_num += adjustment;
1695 size_t pending_cards = predict_pending_cards();
1696 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1697 predict_rs_length_diff();
1698 size_t card_num;
1699 if (full_young_gcs())
1700 card_num = predict_young_card_num(rs_lengths);
1701 else
1702 card_num = predict_non_young_card_num(rs_lengths);
1703 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1704 double accum_yg_surv_rate =
1705 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1706
1707 size_t bytes_to_copy =
1708 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1709
1710 return
1711 predict_rs_update_time_ms(pending_cards) +
1712 predict_rs_scan_time_ms(card_num) +
1713 predict_object_copy_time_ms(bytes_to_copy) +
1714 predict_young_other_time_ms(young_num) +
1715 predict_constant_other_time_ms();
1716 }
1717
1718 double
1719 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1720 size_t rs_length = predict_rs_length_diff();
1721 size_t card_num;
1722 if (full_young_gcs())
1723 card_num = predict_young_card_num(rs_length);
1724 else
1725 card_num = predict_non_young_card_num(rs_length);
1726 return predict_base_elapsed_time_ms(pending_cards, card_num);
1727 }
1728
1729 double
1730 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1731 size_t scanned_cards) {
1732 return
1733 predict_rs_update_time_ms(pending_cards) +
1734 predict_rs_scan_time_ms(scanned_cards) +
1735 predict_constant_other_time_ms();
1736 }
1737
1738 double
1739 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1740 bool young) {
1741 size_t rs_length = hr->rem_set()->occupied();
1742 size_t card_num;
1743 if (full_young_gcs())
1744 card_num = predict_young_card_num(rs_length);
1745 else
1746 card_num = predict_non_young_card_num(rs_length);
1747 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1748
1749 double region_elapsed_time_ms =
1750 predict_rs_scan_time_ms(card_num) +
1751 predict_object_copy_time_ms(bytes_to_copy);
1752
1753 if (young)
1754 region_elapsed_time_ms += predict_young_other_time_ms(1);
1755 else
1756 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1757
1758 return region_elapsed_time_ms;
1759 }
1760
1761 size_t
1762 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1763 size_t bytes_to_copy;
1764 if (hr->is_marked())
1765 bytes_to_copy = hr->max_live_bytes();
1766 else {
1767 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1768 "invariant" );
1769 int age = hr->age_in_surv_rate_group();
1770 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1771 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1772 }
1773
1774 return bytes_to_copy;
1775 }
1776
1777 void
1778 G1CollectorPolicy::start_recording_regions() {
1779 _recorded_rs_lengths = 0;
1780 _recorded_young_regions = 0;
1781 _recorded_non_young_regions = 0;
1782
1783 #if PREDICTIONS_VERBOSE
1784 _recorded_marked_bytes = 0;
1785 _recorded_young_bytes = 0;
1786 _predicted_bytes_to_copy = 0;
1787 _predicted_rs_lengths = 0;
1788 _predicted_cards_scanned = 0;
1789 #endif // PREDICTIONS_VERBOSE
1790 }
1791
1792 void
1793 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1794 #if PREDICTIONS_VERBOSE
1795 if (!young) {
1796 _recorded_marked_bytes += hr->max_live_bytes();
1797 }
1798 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1799 #endif // PREDICTIONS_VERBOSE
1800
1801 size_t rs_length = hr->rem_set()->occupied();
1802 _recorded_rs_lengths += rs_length;
1803 }
1804
1805 void
1806 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1807 assert(!hr->is_young(), "should not call this");
1808 ++_recorded_non_young_regions;
1809 record_cset_region_info(hr, false);
1810 }
1811
1812 void
1813 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1814 _recorded_young_regions = n_regions;
1815 }
1816
1817 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1818 #if PREDICTIONS_VERBOSE
1819 _recorded_young_bytes = bytes;
1820 #endif // PREDICTIONS_VERBOSE
1821 }
1822
1823 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1824 _recorded_rs_lengths = rs_lengths;
1825 }
1826
1827 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1828 _predicted_bytes_to_copy = bytes;
1829 }
1830
1831 void
1832 G1CollectorPolicy::end_recording_regions() {
1833 // The _predicted_pause_time_ms field is referenced in code
1834 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1835 _predicted_pause_time_ms = -1.0;
1836
1837 #if PREDICTIONS_VERBOSE
1838 _predicted_pending_cards = predict_pending_cards();
1839 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1840 if (full_young_gcs())
1841 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1842 else
1843 _predicted_cards_scanned +=
1844 predict_non_young_card_num(_predicted_rs_lengths);
1845 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1846
1847 _predicted_rs_update_time_ms =
1848 predict_rs_update_time_ms(_g1->pending_card_num());
1849 _predicted_rs_scan_time_ms =
1850 predict_rs_scan_time_ms(_predicted_cards_scanned);
1851 _predicted_object_copy_time_ms =
1852 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1853 _predicted_constant_other_time_ms =
1854 predict_constant_other_time_ms();
1855 _predicted_young_other_time_ms =
1856 predict_young_other_time_ms(_recorded_young_regions);
1857 _predicted_non_young_other_time_ms =
1858 predict_non_young_other_time_ms(_recorded_non_young_regions);
1859
1860 _predicted_pause_time_ms =
1861 _predicted_rs_update_time_ms +
1862 _predicted_rs_scan_time_ms +
1863 _predicted_object_copy_time_ms +
1864 _predicted_constant_other_time_ms +
1865 _predicted_young_other_time_ms +
1866 _predicted_non_young_other_time_ms;
1867 #endif // PREDICTIONS_VERBOSE
1868 }
1869
1870 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1871 predicted_time_ms) {
1872 // I don't think we need to do this when in young GC mode since
1873 // marking will be initiated next time we hit the soft limit anyway...
1874 if (predicted_time_ms > _expensive_region_limit_ms) {
1875 if (!in_young_gc_mode()) {
1876 set_full_young_gcs(true);
1877 // We might want to do something different here. However,
1878 // right now we don't support the non-generational G1 mode
1879 // (and in fact we are planning to remove the associated code,
1880 // see CR 6814390). So, let's leave it as is and this will be
1881 // removed some time in the future
1882 ShouldNotReachHere();
1883 set_during_initial_mark_pause();
1884 } else
1885 // no point in doing another partial one
1886 _should_revert_to_full_young_gcs = true;
1887 }
1888 }
1889
1890 // </NEW PREDICTION>
1891
1892
1893 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1894 double elapsed_ms) {
1895 _recent_gc_times_ms->add(elapsed_ms);
1896 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1897 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1898 }
1899
1900 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1901 if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
1902 else return _recent_pause_times_ms->avg();
1903 }
1904
1905 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
1906 if (_recent_CH_strong_roots_times_ms->num() == 0)
1907 return (double)MaxGCPauseMillis/3.0;
1908 else return _recent_CH_strong_roots_times_ms->avg();
1909 }
1910
1911 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
1912 if (_recent_G1_strong_roots_times_ms->num() == 0)
1913 return (double)MaxGCPauseMillis/3.0;
1914 else return _recent_G1_strong_roots_times_ms->avg();
1915 }
1916
1917 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
1918 if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
1919 else return _recent_evac_times_ms->avg();
1920 }
1921
1922 int G1CollectorPolicy::number_of_recent_gcs() {
1923 assert(_recent_CH_strong_roots_times_ms->num() ==
1924 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
1925 assert(_recent_G1_strong_roots_times_ms->num() ==
1926 _recent_evac_times_ms->num(), "Sequence out of sync");
1927 assert(_recent_evac_times_ms->num() ==
1928 _recent_pause_times_ms->num(), "Sequence out of sync");
1929 assert(_recent_pause_times_ms->num() ==
1930 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1931 assert(_recent_CS_bytes_used_before->num() ==
1932 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1933 return _recent_pause_times_ms->num();
1934 }
1935
1936 double G1CollectorPolicy::recent_avg_survival_fraction() {
1937 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1938 _recent_CS_bytes_used_before);
1939 }
1940
1941 double G1CollectorPolicy::last_survival_fraction() {
1942 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1943 _recent_CS_bytes_used_before);
1944 }
1945
1946 double
1947 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1948 TruncatedSeq* before) {
1949 assert(surviving->num() == before->num(), "Sequence out of sync");
1950 if (before->sum() > 0.0) {
1951 double recent_survival_rate = surviving->sum() / before->sum();
1952 // We exempt parallel collection from this check because Alloc Buffer
1953 // fragmentation can produce negative collections.
1954 // Further, we're now always doing parallel collection. But I'm still
1955 // leaving this here as a placeholder for a more precise assertion later.
1956 // (DLD, 10/05.)
1957 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1958 _g1->evacuation_failed() ||
1959 recent_survival_rate <= 1.0, "Or bad frac");
1960 return recent_survival_rate;
1961 } else {
1962 return 1.0; // Be conservative.
1963 }
1964 }
1965
1966 double
1967 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
1968 TruncatedSeq* before) {
1969 assert(surviving->num() == before->num(), "Sequence out of sync");
1970 if (surviving->num() > 0 && before->last() > 0.0) {
1971 double last_survival_rate = surviving->last() / before->last();
1972 // We exempt parallel collection from this check because Alloc Buffer
1973 // fragmentation can produce negative collections.
1974 // Further, we're now always doing parallel collection. But I'm still
1975 // leaving this here as a placeholder for a more precise assertion later.
1976 // (DLD, 10/05.)
1977 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1978 last_survival_rate <= 1.0, "Or bad frac");
1979 return last_survival_rate;
1980 } else {
1981 return 1.0;
1982 }
1983 }
1984
1985 static const int survival_min_obs = 5;
1986 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
1987 static const double min_survival_rate = 0.1;
1988
1989 double
1990 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
1991 double latest) {
1992 double res = avg;
1993 if (number_of_recent_gcs() < survival_min_obs) {
1994 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
1995 }
1996 res = MAX2(res, latest);
1997 res = MAX2(res, min_survival_rate);
1998 // In the parallel case, LAB fragmentation can produce "negative
1999 // collections"; so can evac failure. Cap at 1.0
2000 res = MIN2(res, 1.0);
2001 return res;
2002 }
2003
2004 size_t G1CollectorPolicy::expansion_amount() {
2005 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
2006 // We will double the existing space, or take
2007 // G1ExpandByPercentOfAvailable % of the available expansion
2008 // space, whichever is smaller, bounded below by a minimum
2009 // expansion (unless that's all that's left.)
2010 const size_t min_expand_bytes = 1*M;
2011 size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
2012 size_t committed_bytes = _g1->capacity();
2013 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2014 size_t expand_bytes;
2015 size_t expand_bytes_via_pct =
2016 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2017 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2018 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2019 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2020 if (G1PolicyVerbose > 1) {
2021 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2022 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2023 " Answer = %d.\n",
2024 recent_avg_pause_time_ratio(),
2025 byte_size_in_proper_unit(committed_bytes),
2026 proper_unit_for_byte_size(committed_bytes),
2027 byte_size_in_proper_unit(uncommitted_bytes),
2028 proper_unit_for_byte_size(uncommitted_bytes),
2029 byte_size_in_proper_unit(expand_bytes_via_pct),
2030 proper_unit_for_byte_size(expand_bytes_via_pct),
2031 byte_size_in_proper_unit(expand_bytes),
2032 proper_unit_for_byte_size(expand_bytes));
2033 }
2034 return expand_bytes;
2035 } else {
2036 return 0;
2037 }
2038 }
2039
2040 void G1CollectorPolicy::note_start_of_mark_thread() {
2041 _mark_thread_startup_sec = os::elapsedTime();
2042 }
2043
2044 class CountCSClosure: public HeapRegionClosure {
2045 G1CollectorPolicy* _g1_policy;
2046 public:
2047 CountCSClosure(G1CollectorPolicy* g1_policy) :
2048 _g1_policy(g1_policy) {}
2049 bool doHeapRegion(HeapRegion* r) {
2050 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2051 return false;
2052 }
2053 };
2054
2055 void G1CollectorPolicy::count_CS_bytes_used() {
2056 CountCSClosure cs_closure(this);
2057 _g1->collection_set_iterate(&cs_closure);
2058 }
2059
2060 static void print_indent(int level) {
2061 for (int j = 0; j < level+1; ++j)
2062 gclog_or_tty->print(" ");
2063 }
2064
2065 void G1CollectorPolicy::print_summary (int level,
2066 const char* str,
2067 NumberSeq* seq) const {
2068 double sum = seq->sum();
2069 print_indent(level);
2070 gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2071 str, sum / 1000.0, seq->avg());
2072 }
2073
2074 void G1CollectorPolicy::print_summary_sd (int level,
2075 const char* str,
2076 NumberSeq* seq) const {
2077 print_summary(level, str, seq);
2078 print_indent(level + 5);
2079 gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2080 seq->num(), seq->sd(), seq->maximum());
2081 }
2082
2083 void G1CollectorPolicy::check_other_times(int level,
2084 NumberSeq* other_times_ms,
2085 NumberSeq* calc_other_times_ms) const {
2086 bool should_print = false;
2087
2088 double max_sum = MAX2(fabs(other_times_ms->sum()),
2089 fabs(calc_other_times_ms->sum()));
2090 double min_sum = MIN2(fabs(other_times_ms->sum()),
2091 fabs(calc_other_times_ms->sum()));
2092 double sum_ratio = max_sum / min_sum;
2093 if (sum_ratio > 1.1) {
2094 should_print = true;
2095 print_indent(level + 1);
2096 gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2097 }
2098
2099 double max_avg = MAX2(fabs(other_times_ms->avg()),
2100 fabs(calc_other_times_ms->avg()));
2101 double min_avg = MIN2(fabs(other_times_ms->avg()),
2102 fabs(calc_other_times_ms->avg()));
2103 double avg_ratio = max_avg / min_avg;
2104 if (avg_ratio > 1.1) {
2105 should_print = true;
2106 print_indent(level + 1);
2107 gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2108 }
2109
2110 if (other_times_ms->sum() < -0.01) {
2111 print_indent(level + 1);
2112 gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2113 }
2114
2115 if (other_times_ms->avg() < -0.01) {
2116 print_indent(level + 1);
2117 gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2118 }
2119
2120 if (calc_other_times_ms->sum() < -0.01) {
2121 should_print = true;
2122 print_indent(level + 1);
2123 gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2124 }
2125
2126 if (calc_other_times_ms->avg() < -0.01) {
2127 should_print = true;
2128 print_indent(level + 1);
2129 gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2130 }
2131
2132 if (should_print)
2133 print_summary(level, "Other(Calc)", calc_other_times_ms);
2134 }
2135
2136 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2137 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
2138 MainBodySummary* body_summary = summary->main_body_summary();
2139 if (summary->get_total_seq()->num() > 0) {
2140 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2141 if (body_summary != NULL) {
2142 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2143 if (parallel) {
2144 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2145 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2146 print_summary(2, "Ext Root Scanning",
2147 body_summary->get_ext_root_scan_seq());
2148 print_summary(2, "Mark Stack Scanning",
2149 body_summary->get_mark_stack_scan_seq());
2150 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2151 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2152 print_summary(2, "Termination", body_summary->get_termination_seq());
2153 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2154 {
2155 NumberSeq* other_parts[] = {
2156 body_summary->get_update_rs_seq(),
2157 body_summary->get_ext_root_scan_seq(),
2158 body_summary->get_mark_stack_scan_seq(),
2159 body_summary->get_scan_rs_seq(),
2160 body_summary->get_obj_copy_seq(),
2161 body_summary->get_termination_seq()
2162 };
2163 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2164 6, other_parts);
2165 check_other_times(2, body_summary->get_parallel_other_seq(),
2166 &calc_other_times_ms);
2167 }
2168 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2169 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2170 } else {
2171 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2172 print_summary(1, "Ext Root Scanning",
2173 body_summary->get_ext_root_scan_seq());
2174 print_summary(1, "Mark Stack Scanning",
2175 body_summary->get_mark_stack_scan_seq());
2176 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2177 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2178 }
2179 }
2180 print_summary(1, "Other", summary->get_other_seq());
2181 {
2182 if (body_summary != NULL) {
2183 NumberSeq calc_other_times_ms;
2184 if (parallel) {
2185 // parallel
2186 NumberSeq* other_parts[] = {
2187 body_summary->get_satb_drain_seq(),
2188 body_summary->get_parallel_seq(),
2189 body_summary->get_clear_ct_seq()
2190 };
2191 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2192 3, other_parts);
2193 } else {
2194 // serial
2195 NumberSeq* other_parts[] = {
2196 body_summary->get_satb_drain_seq(),
2197 body_summary->get_update_rs_seq(),
2198 body_summary->get_ext_root_scan_seq(),
2199 body_summary->get_mark_stack_scan_seq(),
2200 body_summary->get_scan_rs_seq(),
2201 body_summary->get_obj_copy_seq()
2202 };
2203 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2204 6, other_parts);
2205 }
2206 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2207 }
2208 }
2209 } else {
2210 print_indent(0);
2211 gclog_or_tty->print_cr("none");
2212 }
2213 gclog_or_tty->print_cr("");
2214 }
2215
2216 void G1CollectorPolicy::print_tracing_info() const {
2217 if (TraceGen0Time) {
2218 gclog_or_tty->print_cr("ALL PAUSES");
2219 print_summary_sd(0, "Total", _all_pause_times_ms);
2220 gclog_or_tty->print_cr("");
2221 gclog_or_tty->print_cr("");
2222 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2223 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2224 gclog_or_tty->print_cr("");
2225
2226 gclog_or_tty->print_cr("EVACUATION PAUSES");
2227 print_summary(_summary);
2228
2229 gclog_or_tty->print_cr("MISC");
2230 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2231 print_summary_sd(0, "Yields", _all_yield_times_ms);
2232 for (int i = 0; i < _aux_num; ++i) {
2233 if (_all_aux_times_ms[i].num() > 0) {
2234 char buffer[96];
2235 sprintf(buffer, "Aux%d", i);
2236 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2237 }
2238 }
2239
2240 size_t all_region_num = _region_num_young + _region_num_tenured;
2241 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2242 "Tenured %8d (%6.2lf%%)",
2243 all_region_num,
2244 _region_num_young,
2245 (double) _region_num_young / (double) all_region_num * 100.0,
2246 _region_num_tenured,
2247 (double) _region_num_tenured / (double) all_region_num * 100.0);
2248 }
2249 if (TraceGen1Time) {
2250 if (_all_full_gc_times_ms->num() > 0) {
2251 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2252 _all_full_gc_times_ms->num(),
2253 _all_full_gc_times_ms->sum() / 1000.0);
2254 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2255 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2256 _all_full_gc_times_ms->sd(),
2257 _all_full_gc_times_ms->maximum());
2258 }
2259 }
2260 }
2261
2262 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2263 #ifndef PRODUCT
2264 _short_lived_surv_rate_group->print_surv_rate_summary();
2265 // add this call for any other surv rate groups
2266 #endif // PRODUCT
2267 }
2268
2269 bool
2270 G1CollectorPolicy::should_add_next_region_to_young_list() {
2271 assert(in_young_gc_mode(), "should be in young GC mode");
2272 bool ret;
2273 size_t young_list_length = _g1->young_list()->length();
2274 size_t young_list_max_length = _young_list_target_length;
2275 if (G1FixedEdenSize) {
2276 young_list_max_length -= _max_survivor_regions;
2277 }
2278 if (young_list_length < young_list_max_length) {
2279 ret = true;
2280 ++_region_num_young;
2281 } else {
2282 ret = false;
2283 ++_region_num_tenured;
2284 }
2285
2286 return ret;
2287 }
2288
2289 #ifndef PRODUCT
2290 // for debugging, bit of a hack...
2291 static char*
2292 region_num_to_mbs(int length) {
2293 static char buffer[64];
2294 double bytes = (double) (length * HeapRegion::GrainBytes);
2295 double mbs = bytes / (double) (1024 * 1024);
2296 sprintf(buffer, "%7.2lfMB", mbs);
2297 return buffer;
2298 }
2299 #endif // PRODUCT
2300
2301 size_t G1CollectorPolicy::max_regions(int purpose) {
2302 switch (purpose) {
2303 case GCAllocForSurvived:
2304 return _max_survivor_regions;
2305 case GCAllocForTenured:
2306 return REGIONS_UNLIMITED;
2307 default:
2308 ShouldNotReachHere();
2309 return REGIONS_UNLIMITED;
2310 };
2311 }
2312
2313 // Calculates survivor space parameters.
2314 void G1CollectorPolicy::calculate_survivors_policy()
2315 {
2316 if (G1FixedSurvivorSpaceSize == 0) {
2317 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2318 } else {
2319 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2320 }
2321
2322 if (G1FixedTenuringThreshold) {
2323 _tenuring_threshold = MaxTenuringThreshold;
2324 } else {
2325 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2326 HeapRegion::GrainWords * _max_survivor_regions);
2327 }
2328 }
2329
2330 bool
2331 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
2332 word_size) {
2333 assert(_g1->regions_accounted_for(), "Region leakage!");
2334 double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
2335
2336 size_t young_list_length = _g1->young_list()->length();
2337 size_t young_list_max_length = _young_list_target_length;
2338 if (G1FixedEdenSize) {
2339 young_list_max_length -= _max_survivor_regions;
2340 }
2341 bool reached_target_length = young_list_length >= young_list_max_length;
2342
2343 if (in_young_gc_mode()) {
2344 if (reached_target_length) {
2345 assert( young_list_length > 0 && _g1->young_list()->length() > 0,
2346 "invariant" );
2347 return true;
2348 }
2349 } else {
2350 guarantee( false, "should not reach here" );
2351 }
2352
2353 return false;
2354 }
2355
2356 #ifndef PRODUCT
2357 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2358 CollectionSetChooser* _chooser;
2359 public:
2360 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2361 _chooser(chooser) {}
2362
2363 bool doHeapRegion(HeapRegion* r) {
2364 if (!r->continuesHumongous()) {
2365 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2366 }
2367 return false;
2368 }
2369 };
2370
2371 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2372 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2373 _g1->heap_region_iterate(&cl);
2374 return true;
2375 }
2376 #endif
2377
2378 bool
2379 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2380 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2381 if (!during_cycle) {
2382 set_initiate_conc_mark_if_possible();
2383 return true;
2384 } else {
2385 return false;
2386 }
2387 }
2388
2389 void
2390 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2391 // We are about to decide on whether this pause will be an
2392 // initial-mark pause.
2393
2394 // First, during_initial_mark_pause() should not be already set. We
2395 // will set it here if we have to. However, it should be cleared by
2396 // the end of the pause (it's only set for the duration of an
2397 // initial-mark pause).
2398 assert(!during_initial_mark_pause(), "pre-condition");
2399
2400 if (initiate_conc_mark_if_possible()) {
2401 // We had noticed on a previous pause that the heap occupancy has
2402 // gone over the initiating threshold and we should start a
2403 // concurrent marking cycle. So we might initiate one.
2404
2405 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2406 if (!during_cycle) {
2407 // The concurrent marking thread is not "during a cycle", i.e.,
2408 // it has completed the last one. So we can go ahead and
2409 // initiate a new cycle.
2410
2411 set_during_initial_mark_pause();
2412
2413 // And we can now clear initiate_conc_mark_if_possible() as
2414 // we've already acted on it.
2415 clear_initiate_conc_mark_if_possible();
2416 } else {
2417 // The concurrent marking thread is still finishing up the
2418 // previous cycle. If we start one right now the two cycles
2419 // overlap. In particular, the concurrent marking thread might
2420 // be in the process of clearing the next marking bitmap (which
2421 // we will use for the next cycle if we start one). Starting a
2422 // cycle now will be bad given that parts of the marking
2423 // information might get cleared by the marking thread. And we
2424 // cannot wait for the marking thread to finish the cycle as it
2425 // periodically yields while clearing the next marking bitmap
2426 // and, if it's in a yield point, it's waiting for us to
2427 // finish. So, at this point we will not start a cycle and we'll
2428 // let the concurrent marking thread complete the last one.
2429 }
2430 }
2431 }
2432
2433 void
2434 G1CollectorPolicy_BestRegionsFirst::
2435 record_collection_pause_start(double start_time_sec, size_t start_used) {
2436 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2437 }
2438
2439 class NextNonCSElemFinder: public HeapRegionClosure {
2440 HeapRegion* _res;
2441 public:
2442 NextNonCSElemFinder(): _res(NULL) {}
2443 bool doHeapRegion(HeapRegion* r) {
2444 if (!r->in_collection_set()) {
2445 _res = r;
2446 return true;
2447 } else {
2448 return false;
2449 }
2450 }
2451 HeapRegion* res() { return _res; }
2452 };
2453
2454 class KnownGarbageClosure: public HeapRegionClosure {
2455 CollectionSetChooser* _hrSorted;
2456
2457 public:
2458 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2459 _hrSorted(hrSorted)
2460 {}
2461
2462 bool doHeapRegion(HeapRegion* r) {
2463 // We only include humongous regions in collection
2464 // sets when concurrent mark shows that their contained object is
2465 // unreachable.
2466
2467 // Do we have any marking information for this region?
2468 if (r->is_marked()) {
2469 // We don't include humongous regions in collection
2470 // sets because we collect them immediately at the end of a marking
2471 // cycle. We also don't include young regions because we *must*
2472 // include them in the next collection pause.
2473 if (!r->isHumongous() && !r->is_young()) {
2474 _hrSorted->addMarkedHeapRegion(r);
2475 }
2476 }
2477 return false;
2478 }
2479 };
2480
2481 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2482 CollectionSetChooser* _hrSorted;
2483 jint _marked_regions_added;
2484 jint _chunk_size;
2485 jint _cur_chunk_idx;
2486 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2487 int _worker;
2488 int _invokes;
2489
2490 void get_new_chunk() {
2491 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2492 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2493 }
2494 void add_region(HeapRegion* r) {
2495 if (_cur_chunk_idx == _cur_chunk_end) {
2496 get_new_chunk();
2497 }
2498 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2499 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2500 _marked_regions_added++;
2501 _cur_chunk_idx++;
2502 }
2503
2504 public:
2505 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2506 jint chunk_size,
2507 int worker) :
2508 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2509 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2510 _invokes(0)
2511 {}
2512
2513 bool doHeapRegion(HeapRegion* r) {
2514 // We only include humongous regions in collection
2515 // sets when concurrent mark shows that their contained object is
2516 // unreachable.
2517 _invokes++;
2518
2519 // Do we have any marking information for this region?
2520 if (r->is_marked()) {
2521 // We don't include humongous regions in collection
2522 // sets because we collect them immediately at the end of a marking
2523 // cycle.
2524 // We also do not include young regions in collection sets
2525 if (!r->isHumongous() && !r->is_young()) {
2526 add_region(r);
2527 }
2528 }
2529 return false;
2530 }
2531 jint marked_regions_added() { return _marked_regions_added; }
2532 int invokes() { return _invokes; }
2533 };
2534
2535 class ParKnownGarbageTask: public AbstractGangTask {
2536 CollectionSetChooser* _hrSorted;
2537 jint _chunk_size;
2538 G1CollectedHeap* _g1;
2539 public:
2540 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2541 AbstractGangTask("ParKnownGarbageTask"),
2542 _hrSorted(hrSorted), _chunk_size(chunk_size),
2543 _g1(G1CollectedHeap::heap())
2544 {}
2545
2546 void work(int i) {
2547 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2548 // Back to zero for the claim value.
2549 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2550 HeapRegion::InitialClaimValue);
2551 jint regions_added = parKnownGarbageCl.marked_regions_added();
2552 _hrSorted->incNumMarkedHeapRegions(regions_added);
2553 if (G1PrintParCleanupStats) {
2554 gclog_or_tty->print(" Thread %d called %d times, added %d regions to list.\n",
2555 i, parKnownGarbageCl.invokes(), regions_added);
2556 }
2557 }
2558 };
2559
2560 void
2561 G1CollectorPolicy_BestRegionsFirst::
2562 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2563 size_t max_live_bytes) {
2564 double start;
2565 if (G1PrintParCleanupStats) start = os::elapsedTime();
2566 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2567
2568 _collectionSetChooser->clearMarkedHeapRegions();
2569 double clear_marked_end;
2570 if (G1PrintParCleanupStats) {
2571 clear_marked_end = os::elapsedTime();
2572 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2573 (clear_marked_end - start)*1000.0);
2574 }
2575 if (G1CollectedHeap::use_parallel_gc_threads()) {
2576 const size_t OverpartitionFactor = 4;
2577 const size_t MinWorkUnit = 8;
2578 const size_t WorkUnit =
2579 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2580 MinWorkUnit);
2581 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2582 WorkUnit);
2583 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2584 (int) WorkUnit);
2585 _g1->workers()->run_task(&parKnownGarbageTask);
2586
2587 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2588 "sanity check");
2589 } else {
2590 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2591 _g1->heap_region_iterate(&knownGarbagecl);
2592 }
2593 double known_garbage_end;
2594 if (G1PrintParCleanupStats) {
2595 known_garbage_end = os::elapsedTime();
2596 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2597 (known_garbage_end - clear_marked_end)*1000.0);
2598 }
2599 _collectionSetChooser->sortMarkedHeapRegions();
2600 double sort_end;
2601 if (G1PrintParCleanupStats) {
2602 sort_end = os::elapsedTime();
2603 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2604 (sort_end - known_garbage_end)*1000.0);
2605 }
2606
2607 record_concurrent_mark_cleanup_end_work2();
2608 double work2_end;
2609 if (G1PrintParCleanupStats) {
2610 work2_end = os::elapsedTime();
2611 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2612 (work2_end - sort_end)*1000.0);
2613 }
2614 }
2615
2616 // Add the heap region at the head of the non-incremental collection set
2617 void G1CollectorPolicy::
2618 add_to_collection_set(HeapRegion* hr) {
2619 assert(_inc_cset_build_state == Active, "Precondition");
2620 assert(!hr->is_young(), "non-incremental add of young region");
2621
2622 if (G1PrintHeapRegions) {
2623 gclog_or_tty->print_cr("added region to cset "
2624 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2625 "top "PTR_FORMAT", %s",
2626 hr->hrs_index(), hr->bottom(), hr->end(),
2627 hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
2628 }
2629
2630 if (_g1->mark_in_progress())
2631 _g1->concurrent_mark()->registerCSetRegion(hr);
2632
2633 assert(!hr->in_collection_set(), "should not already be in the CSet");
2634 hr->set_in_collection_set(true);
2635 hr->set_next_in_collection_set(_collection_set);
2636 _collection_set = hr;
2637 _collection_set_size++;
2638 _collection_set_bytes_used_before += hr->used();
2639 _g1->register_region_with_in_cset_fast_test(hr);
2640 }
2641
2642 // Initialize the per-collection-set information
2643 void G1CollectorPolicy::start_incremental_cset_building() {
2644 assert(_inc_cset_build_state == Inactive, "Precondition");
2645
2646 _inc_cset_head = NULL;
2647 _inc_cset_tail = NULL;
2648 _inc_cset_size = 0;
2649 _inc_cset_bytes_used_before = 0;
2650
2651 if (in_young_gc_mode()) {
2652 _inc_cset_young_index = 0;
2653 }
2654
2655 _inc_cset_max_finger = 0;
2656 _inc_cset_recorded_young_bytes = 0;
2657 _inc_cset_recorded_rs_lengths = 0;
2658 _inc_cset_predicted_elapsed_time_ms = 0;
2659 _inc_cset_predicted_bytes_to_copy = 0;
2660 _inc_cset_build_state = Active;
2661 }
2662
2663 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2664 // This routine is used when:
2665 // * adding survivor regions to the incremental cset at the end of an
2666 // evacuation pause,
2667 // * adding the current allocation region to the incremental cset
2668 // when it is retired, and
2669 // * updating existing policy information for a region in the
2670 // incremental cset via young list RSet sampling.
2671 // Therefore this routine may be called at a safepoint by the
2672 // VM thread, or in-between safepoints by mutator threads (when
2673 // retiring the current allocation region) or a concurrent
2674 // refine thread (RSet sampling).
2675
2676 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2677 size_t used_bytes = hr->used();
2678
2679 _inc_cset_recorded_rs_lengths += rs_length;
2680 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2681
2682 _inc_cset_bytes_used_before += used_bytes;
2683
2684 // Cache the values we have added to the aggregated informtion
2685 // in the heap region in case we have to remove this region from
2686 // the incremental collection set, or it is updated by the
2687 // rset sampling code
2688 hr->set_recorded_rs_length(rs_length);
2689 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2690
2691 #if PREDICTIONS_VERBOSE
2692 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2693 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2694
2695 // Record the number of bytes used in this region
2696 _inc_cset_recorded_young_bytes += used_bytes;
2697
2698 // Cache the values we have added to the aggregated informtion
2699 // in the heap region in case we have to remove this region from
2700 // the incremental collection set, or it is updated by the
2701 // rset sampling code
2702 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2703 #endif // PREDICTIONS_VERBOSE
2704 }
2705
2706 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2707 // This routine is currently only called as part of the updating of
2708 // existing policy information for regions in the incremental cset that
2709 // is performed by the concurrent refine thread(s) as part of young list
2710 // RSet sampling. Therefore we should not be at a safepoint.
2711
2712 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2713 assert(hr->is_young(), "it should be");
2714
2715 size_t used_bytes = hr->used();
2716 size_t old_rs_length = hr->recorded_rs_length();
2717 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2718
2719 // Subtract the old recorded/predicted policy information for
2720 // the given heap region from the collection set info.
2721 _inc_cset_recorded_rs_lengths -= old_rs_length;
2722 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2723
2724 _inc_cset_bytes_used_before -= used_bytes;
2725
2726 // Clear the values cached in the heap region
2727 hr->set_recorded_rs_length(0);
2728 hr->set_predicted_elapsed_time_ms(0);
2729
2730 #if PREDICTIONS_VERBOSE
2731 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2732 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2733
2734 // Subtract the number of bytes used in this region
2735 _inc_cset_recorded_young_bytes -= used_bytes;
2736
2737 // Clear the values cached in the heap region
2738 hr->set_predicted_bytes_to_copy(0);
2739 #endif // PREDICTIONS_VERBOSE
2740 }
2741
2742 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2743 // Update the collection set information that is dependent on the new RS length
2744 assert(hr->is_young(), "Precondition");
2745
2746 remove_from_incremental_cset_info(hr);
2747 add_to_incremental_cset_info(hr, new_rs_length);
2748 }
2749
2750 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2751 assert( hr->is_young(), "invariant");
2752 assert( hr->young_index_in_cset() == -1, "invariant" );
2753 assert(_inc_cset_build_state == Active, "Precondition");
2754
2755 // We need to clear and set the cached recorded/cached collection set
2756 // information in the heap region here (before the region gets added
2757 // to the collection set). An individual heap region's cached values
2758 // are calculated, aggregated with the policy collection set info,
2759 // and cached in the heap region here (initially) and (subsequently)
2760 // by the Young List sampling code.
2761
2762 size_t rs_length = hr->rem_set()->occupied();
2763 add_to_incremental_cset_info(hr, rs_length);
2764
2765 HeapWord* hr_end = hr->end();
2766 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2767
2768 assert(!hr->in_collection_set(), "invariant");
2769 hr->set_in_collection_set(true);
2770 assert( hr->next_in_collection_set() == NULL, "invariant");
2771
2772 _inc_cset_size++;
2773 _g1->register_region_with_in_cset_fast_test(hr);
2774
2775 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2776 ++_inc_cset_young_index;
2777 }
2778
2779 // Add the region at the RHS of the incremental cset
2780 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2781 // We should only ever be appending survivors at the end of a pause
2782 assert( hr->is_survivor(), "Logic");
2783
2784 // Do the 'common' stuff
2785 add_region_to_incremental_cset_common(hr);
2786
2787 // Now add the region at the right hand side
2788 if (_inc_cset_tail == NULL) {
2789 assert(_inc_cset_head == NULL, "invariant");
2790 _inc_cset_head = hr;
2791 } else {
2792 _inc_cset_tail->set_next_in_collection_set(hr);
2793 }
2794 _inc_cset_tail = hr;
2795
2796 if (G1PrintHeapRegions) {
2797 gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
2798 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2799 "top "PTR_FORMAT", young %s",
2800 hr->hrs_index(), hr->bottom(), hr->end(),
2801 hr->top(), (hr->is_young()) ? "YES" : "NO");
2802 }
2803 }
2804
2805 // Add the region to the LHS of the incremental cset
2806 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2807 // Survivors should be added to the RHS at the end of a pause
2808 assert(!hr->is_survivor(), "Logic");
2809
2810 // Do the 'common' stuff
2811 add_region_to_incremental_cset_common(hr);
2812
2813 // Add the region at the left hand side
2814 hr->set_next_in_collection_set(_inc_cset_head);
2815 if (_inc_cset_head == NULL) {
2816 assert(_inc_cset_tail == NULL, "Invariant");
2817 _inc_cset_tail = hr;
2818 }
2819 _inc_cset_head = hr;
2820
2821 if (G1PrintHeapRegions) {
2822 gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
2823 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2824 "top "PTR_FORMAT", young %s",
2825 hr->hrs_index(), hr->bottom(), hr->end(),
2826 hr->top(), (hr->is_young()) ? "YES" : "NO");
2827 }
2828 }
2829
2830 #ifndef PRODUCT
2831 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2832 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2833
2834 st->print_cr("\nCollection_set:");
2835 HeapRegion* csr = list_head;
2836 while (csr != NULL) {
2837 HeapRegion* next = csr->next_in_collection_set();
2838 assert(csr->in_collection_set(), "bad CS");
2839 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2840 "age: %4d, y: %d, surv: %d",
2841 csr->bottom(), csr->end(),
2842 csr->top(),
2843 csr->prev_top_at_mark_start(),
2844 csr->next_top_at_mark_start(),
2845 csr->top_at_conc_mark_count(),
2846 csr->age_in_surv_rate_group_cond(),
2847 csr->is_young(),
2848 csr->is_survivor());
2849 csr = next;
2850 }
2851 }
2852 #endif // !PRODUCT
2853
2854 void
2855 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2856 double target_pause_time_ms) {
2857 // Set this here - in case we're not doing young collections.
2858 double non_young_start_time_sec = os::elapsedTime();
2859
2860 start_recording_regions();
2861
2862 guarantee(target_pause_time_ms > 0.0,
2863 err_msg("target_pause_time_ms = %1.6lf should be positive",
2864 target_pause_time_ms));
2865 guarantee(_collection_set == NULL, "Precondition");
2866
2867 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2868 double predicted_pause_time_ms = base_time_ms;
2869
2870 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2871
2872 // the 10% and 50% values are arbitrary...
2873 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2874 time_remaining_ms = 0.50 * target_pause_time_ms;
2875 _within_target = false;
2876 } else {
2877 _within_target = true;
2878 }
2879
2880 // We figure out the number of bytes available for future to-space.
2881 // For new regions without marking information, we must assume the
2882 // worst-case of complete survival. If we have marking information for a
2883 // region, we can bound the amount of live data. We can add a number of
2884 // such regions, as long as the sum of the live data bounds does not
2885 // exceed the available evacuation space.
2886 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2887
2888 size_t expansion_bytes =
2889 _g1->expansion_regions() * HeapRegion::GrainBytes;
2890
2891 _collection_set_bytes_used_before = 0;
2892 _collection_set_size = 0;
2893
2894 // Adjust for expansion and slop.
2895 max_live_bytes = max_live_bytes + expansion_bytes;
2896
2897 assert(_g1->regions_accounted_for(), "Region leakage!");
2898
2899 HeapRegion* hr;
2900 if (in_young_gc_mode()) {
2901 double young_start_time_sec = os::elapsedTime();
2902
2903 if (G1PolicyVerbose > 0) {
2904 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2905 _g1->young_list()->length());
2906 }
2907
2908 _young_cset_length = 0;
2909 _last_young_gc_full = full_young_gcs() ? true : false;
2910
2911 if (_last_young_gc_full)
2912 ++_full_young_pause_num;
2913 else
2914 ++_partial_young_pause_num;
2915
2916 // The young list is laid with the survivor regions from the previous
2917 // pause are appended to the RHS of the young list, i.e.
2918 // [Newly Young Regions ++ Survivors from last pause].
2919
2920 hr = _g1->young_list()->first_survivor_region();
2921 while (hr != NULL) {
2922 assert(hr->is_survivor(), "badly formed young list");
2923 hr->set_young();
2924 hr = hr->get_next_young_region();
2925 }
2926
2927 // Clear the fields that point to the survivor list - they are
2928 // all young now.
2929 _g1->young_list()->clear_survivors();
2930
2931 if (_g1->mark_in_progress())
2932 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2933
2934 _young_cset_length = _inc_cset_young_index;
2935 _collection_set = _inc_cset_head;
2936 _collection_set_size = _inc_cset_size;
2937 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2938
2939 // For young regions in the collection set, we assume the worst
2940 // case of complete survival
2941 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2942
2943 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2944 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2945
2946 // The number of recorded young regions is the incremental
2947 // collection set's current size
2948 set_recorded_young_regions(_inc_cset_size);
2949 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2950 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2951 #if PREDICTIONS_VERBOSE
2952 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2953 #endif // PREDICTIONS_VERBOSE
2954
2955 if (G1PolicyVerbose > 0) {
2956 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2957 _inc_cset_size);
2958 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2959 max_live_bytes/K);
2960 }
2961
2962 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2963
2964 double young_end_time_sec = os::elapsedTime();
2965 _recorded_young_cset_choice_time_ms =
2966 (young_end_time_sec - young_start_time_sec) * 1000.0;
2967
2968 // We are doing young collections so reset this.
2969 non_young_start_time_sec = young_end_time_sec;
2970
2971 // Note we can use either _collection_set_size or
2972 // _young_cset_length here
2973 if (_collection_set_size > 0 && _last_young_gc_full) {
2974 // don't bother adding more regions...
2975 goto choose_collection_set_end;
2976 }
2977 }
2978
2979 if (!in_young_gc_mode() || !full_young_gcs()) {
2980 bool should_continue = true;
2981 NumberSeq seq;
2982 double avg_prediction = 100000000000000000.0; // something very large
2983
2984 do {
2985 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2986 avg_prediction);
2987 if (hr != NULL) {
2988 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2989 time_remaining_ms -= predicted_time_ms;
2990 predicted_pause_time_ms += predicted_time_ms;
2991 add_to_collection_set(hr);
2992 record_non_young_cset_region(hr);
2993 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2994 if (G1PolicyVerbose > 0) {
2995 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2996 max_live_bytes/K);
2997 }
2998 seq.add(predicted_time_ms);
2999 avg_prediction = seq.avg() + seq.sd();
3000 }
3001 should_continue =
3002 ( hr != NULL) &&
3003 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
3004 : _collection_set_size < _young_list_fixed_length );
3005 } while (should_continue);
3006
3007 if (!adaptive_young_list_length() &&
3008 _collection_set_size < _young_list_fixed_length)
3009 _should_revert_to_full_young_gcs = true;
3010 }
3011
3012 choose_collection_set_end:
3013 stop_incremental_cset_building();
3014
3015 count_CS_bytes_used();
3016
3017 end_recording_regions();
3018
3019 double non_young_end_time_sec = os::elapsedTime();
3020 _recorded_non_young_cset_choice_time_ms =
3021 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3022 }
3023
3024 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3025 G1CollectorPolicy::record_full_collection_end();
3026 _collectionSetChooser->updateAfterFullCollection();
3027 }
3028
3029 void G1CollectorPolicy_BestRegionsFirst::
3030 expand_if_possible(size_t numRegions) {
3031 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3032 _g1->expand(expansion_bytes);
3033 }
3034
3035 void G1CollectorPolicy_BestRegionsFirst::
3036 record_collection_pause_end() {
3037 G1CollectorPolicy::record_collection_pause_end();
3038 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3039 }