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