Thu, 22 Apr 2010 15:20:16 -0400
6946048: G1: improvements to +PrintGCDetails output
Summary: Small improvements to G1's PrintGCDetails output. It also includes minor formatting details.
Reviewed-by: ysr, johnc
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.
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23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectorPolicy.cpp.incl"
28 #define PREDICTIONS_VERBOSE 0
30 // <NEW PREDICTION>
32 // Different defaults for different number of GC threads
33 // They were chosen by running GCOld and SPECjbb on debris with different
34 // numbers of GC threads and choosing them based on the results
36 // all the same
37 static double rs_length_diff_defaults[] = {
38 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
39 };
41 static double cost_per_card_ms_defaults[] = {
42 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
43 };
45 // all the same
46 static double fully_young_cards_per_entry_ratio_defaults[] = {
47 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
48 };
50 static double cost_per_entry_ms_defaults[] = {
51 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
52 };
54 static double cost_per_byte_ms_defaults[] = {
55 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
56 };
58 // these should be pretty consistent
59 static double constant_other_time_ms_defaults[] = {
60 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
61 };
64 static double young_other_cost_per_region_ms_defaults[] = {
65 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
66 };
68 static double non_young_other_cost_per_region_ms_defaults[] = {
69 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
70 };
72 // </NEW PREDICTION>
74 G1CollectorPolicy::G1CollectorPolicy() :
75 _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
76 _n_pauses(0),
77 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
78 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
79 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
80 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
81 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
82 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
83 _all_pause_times_ms(new NumberSeq()),
84 _stop_world_start(0.0),
85 _all_stop_world_times_ms(new NumberSeq()),
86 _all_yield_times_ms(new NumberSeq()),
88 _all_mod_union_times_ms(new NumberSeq()),
90 _summary(new Summary()),
91 _abandoned_summary(new AbandonedSummary()),
93 #ifndef PRODUCT
94 _cur_clear_ct_time_ms(0.0),
95 _min_clear_cc_time_ms(-1.0),
96 _max_clear_cc_time_ms(-1.0),
97 _cur_clear_cc_time_ms(0.0),
98 _cum_clear_cc_time_ms(0.0),
99 _num_cc_clears(0L),
100 #endif
102 _region_num_young(0),
103 _region_num_tenured(0),
104 _prev_region_num_young(0),
105 _prev_region_num_tenured(0),
107 _aux_num(10),
108 _all_aux_times_ms(new NumberSeq[_aux_num]),
109 _cur_aux_start_times_ms(new double[_aux_num]),
110 _cur_aux_times_ms(new double[_aux_num]),
111 _cur_aux_times_set(new bool[_aux_num]),
113 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
114 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
115 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
117 // <NEW PREDICTION>
119 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
120 _prev_collection_pause_end_ms(0.0),
121 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
122 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
123 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
124 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
125 _partially_young_cards_per_entry_ratio_seq(
126 new TruncatedSeq(TruncatedSeqLength)),
127 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
128 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
129 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
130 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
131 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
132 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
133 _non_young_other_cost_per_region_ms_seq(
134 new TruncatedSeq(TruncatedSeqLength)),
136 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
137 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
138 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
140 _pause_time_target_ms((double) MaxGCPauseMillis),
142 // </NEW PREDICTION>
144 _in_young_gc_mode(false),
145 _full_young_gcs(true),
146 _full_young_pause_num(0),
147 _partial_young_pause_num(0),
149 _during_marking(false),
150 _in_marking_window(false),
151 _in_marking_window_im(false),
153 _known_garbage_ratio(0.0),
154 _known_garbage_bytes(0),
156 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
157 _target_pause_time_ms(-1.0),
159 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
161 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
162 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
164 _recent_avg_pause_time_ratio(0.0),
165 _num_markings(0),
166 _n_marks(0),
167 _n_pauses_at_mark_end(0),
169 _all_full_gc_times_ms(new NumberSeq()),
171 // G1PausesBtwnConcMark defaults to -1
172 // so the hack is to do the cast QQQ FIXME
173 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
174 _n_marks_since_last_pause(0),
175 _initiate_conc_mark_if_possible(false),
176 _during_initial_mark_pause(false),
177 _should_revert_to_full_young_gcs(false),
178 _last_full_young_gc(false),
180 _prev_collection_pause_used_at_end_bytes(0),
182 _collection_set(NULL),
183 _collection_set_size(0),
184 _collection_set_bytes_used_before(0),
186 // Incremental CSet attributes
187 _inc_cset_build_state(Inactive),
188 _inc_cset_head(NULL),
189 _inc_cset_tail(NULL),
190 _inc_cset_size(0),
191 _inc_cset_young_index(0),
192 _inc_cset_bytes_used_before(0),
193 _inc_cset_max_finger(NULL),
194 _inc_cset_recorded_young_bytes(0),
195 _inc_cset_recorded_rs_lengths(0),
196 _inc_cset_predicted_elapsed_time_ms(0.0),
197 _inc_cset_predicted_bytes_to_copy(0),
199 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
200 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
201 #endif // _MSC_VER
203 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
204 G1YoungSurvRateNumRegionsSummary)),
205 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
206 G1YoungSurvRateNumRegionsSummary)),
207 // add here any more surv rate groups
208 _recorded_survivor_regions(0),
209 _recorded_survivor_head(NULL),
210 _recorded_survivor_tail(NULL),
211 _survivors_age_table(true),
213 _gc_overhead_perc(0.0)
215 {
216 // Set up the region size and associated fields. Given that the
217 // policy is created before the heap, we have to set this up here,
218 // so it's done as soon as possible.
219 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
220 HeapRegionRemSet::setup_remset_size();
222 // Verify PLAB sizes
223 const uint region_size = HeapRegion::GrainWords;
224 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
225 char buffer[128];
226 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
227 OldPLABSize > region_size ? "Old" : "Young", region_size);
228 vm_exit_during_initialization(buffer);
229 }
231 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
232 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
234 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
235 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
236 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
238 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
239 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
241 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
242 _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
244 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
246 _par_last_termination_times_ms = new double[_parallel_gc_threads];
247 _par_last_termination_attempts = new double[_parallel_gc_threads];
248 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
250 // start conservatively
251 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
253 // <NEW PREDICTION>
255 int index;
256 if (ParallelGCThreads == 0)
257 index = 0;
258 else if (ParallelGCThreads > 8)
259 index = 7;
260 else
261 index = ParallelGCThreads - 1;
263 _pending_card_diff_seq->add(0.0);
264 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
265 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
266 _fully_young_cards_per_entry_ratio_seq->add(
267 fully_young_cards_per_entry_ratio_defaults[index]);
268 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
269 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
270 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
271 _young_other_cost_per_region_ms_seq->add(
272 young_other_cost_per_region_ms_defaults[index]);
273 _non_young_other_cost_per_region_ms_seq->add(
274 non_young_other_cost_per_region_ms_defaults[index]);
276 // </NEW PREDICTION>
278 // Below, we might need to calculate the pause time target based on
279 // the pause interval. When we do so we are going to give G1 maximum
280 // flexibility and allow it to do pauses when it needs to. So, we'll
281 // arrange that the pause interval to be pause time target + 1 to
282 // ensure that a) the pause time target is maximized with respect to
283 // the pause interval and b) we maintain the invariant that pause
284 // time target < pause interval. If the user does not want this
285 // maximum flexibility, they will have to set the pause interval
286 // explicitly.
288 // First make sure that, if either parameter is set, its value is
289 // reasonable.
290 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
291 if (MaxGCPauseMillis < 1) {
292 vm_exit_during_initialization("MaxGCPauseMillis should be "
293 "greater than 0");
294 }
295 }
296 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
297 if (GCPauseIntervalMillis < 1) {
298 vm_exit_during_initialization("GCPauseIntervalMillis should be "
299 "greater than 0");
300 }
301 }
303 // Then, if the pause time target parameter was not set, set it to
304 // the default value.
305 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
306 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
307 // The default pause time target in G1 is 200ms
308 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
309 } else {
310 // We do not allow the pause interval to be set without the
311 // pause time target
312 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
313 "without setting MaxGCPauseMillis");
314 }
315 }
317 // Then, if the interval parameter was not set, set it according to
318 // the pause time target (this will also deal with the case when the
319 // pause time target is the default value).
320 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
321 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
322 }
324 // Finally, make sure that the two parameters are consistent.
325 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
326 char buffer[256];
327 jio_snprintf(buffer, 256,
328 "MaxGCPauseMillis (%u) should be less than "
329 "GCPauseIntervalMillis (%u)",
330 MaxGCPauseMillis, GCPauseIntervalMillis);
331 vm_exit_during_initialization(buffer);
332 }
334 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
335 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
336 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
337 _sigma = (double) G1ConfidencePercent / 100.0;
339 // start conservatively (around 50ms is about right)
340 _concurrent_mark_init_times_ms->add(0.05);
341 _concurrent_mark_remark_times_ms->add(0.05);
342 _concurrent_mark_cleanup_times_ms->add(0.20);
343 _tenuring_threshold = MaxTenuringThreshold;
345 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
346 // fixed, then _max_survivor_regions will be calculated at
347 // calculate_young_list_target_length during initialization
348 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
350 assert(GCTimeRatio > 0,
351 "we should have set it to a default value set_g1_gc_flags() "
352 "if a user set it to 0");
353 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
355 initialize_all();
356 }
358 // Increment "i", mod "len"
359 static void inc_mod(int& i, int len) {
360 i++; if (i == len) i = 0;
361 }
363 void G1CollectorPolicy::initialize_flags() {
364 set_min_alignment(HeapRegion::GrainBytes);
365 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
366 if (SurvivorRatio < 1) {
367 vm_exit_during_initialization("Invalid survivor ratio specified");
368 }
369 CollectorPolicy::initialize_flags();
370 }
372 // The easiest way to deal with the parsing of the NewSize /
373 // MaxNewSize / etc. parameteres is to re-use the code in the
374 // TwoGenerationCollectorPolicy class. This is similar to what
375 // ParallelScavenge does with its GenerationSizer class (see
376 // ParallelScavengeHeap::initialize()). We might change this in the
377 // future, but it's a good start.
378 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
379 size_t size_to_region_num(size_t byte_size) {
380 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
381 }
383 public:
384 G1YoungGenSizer() {
385 initialize_flags();
386 initialize_size_info();
387 }
389 size_t min_young_region_num() {
390 return size_to_region_num(_min_gen0_size);
391 }
392 size_t initial_young_region_num() {
393 return size_to_region_num(_initial_gen0_size);
394 }
395 size_t max_young_region_num() {
396 return size_to_region_num(_max_gen0_size);
397 }
398 };
400 void G1CollectorPolicy::init() {
401 // Set aside an initial future to_space.
402 _g1 = G1CollectedHeap::heap();
404 assert(Heap_lock->owned_by_self(), "Locking discipline.");
406 initialize_gc_policy_counters();
408 if (G1Gen) {
409 _in_young_gc_mode = true;
411 G1YoungGenSizer sizer;
412 size_t initial_region_num = sizer.initial_young_region_num();
414 if (UseAdaptiveSizePolicy) {
415 set_adaptive_young_list_length(true);
416 _young_list_fixed_length = 0;
417 } else {
418 set_adaptive_young_list_length(false);
419 _young_list_fixed_length = initial_region_num;
420 }
421 _free_regions_at_end_of_collection = _g1->free_regions();
422 calculate_young_list_min_length();
423 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
424 calculate_young_list_target_length();
425 } else {
426 _young_list_fixed_length = 0;
427 _in_young_gc_mode = false;
428 }
430 // We may immediately start allocating regions and placing them on the
431 // collection set list. Initialize the per-collection set info
432 start_incremental_cset_building();
433 }
435 // Create the jstat counters for the policy.
436 void G1CollectorPolicy::initialize_gc_policy_counters()
437 {
438 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
439 }
441 void G1CollectorPolicy::calculate_young_list_min_length() {
442 _young_list_min_length = 0;
444 if (!adaptive_young_list_length())
445 return;
447 if (_alloc_rate_ms_seq->num() > 3) {
448 double now_sec = os::elapsedTime();
449 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
450 double alloc_rate_ms = predict_alloc_rate_ms();
451 int min_regions = (int) ceil(alloc_rate_ms * when_ms);
452 int current_region_num = (int) _g1->young_list()->length();
453 _young_list_min_length = min_regions + current_region_num;
454 }
455 }
457 void G1CollectorPolicy::calculate_young_list_target_length() {
458 if (adaptive_young_list_length()) {
459 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
460 calculate_young_list_target_length(rs_lengths);
461 } else {
462 if (full_young_gcs())
463 _young_list_target_length = _young_list_fixed_length;
464 else
465 _young_list_target_length = _young_list_fixed_length / 2;
467 _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
468 }
469 calculate_survivors_policy();
470 }
472 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
473 guarantee( adaptive_young_list_length(), "pre-condition" );
474 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
476 double start_time_sec = os::elapsedTime();
477 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
478 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
479 size_t reserve_regions =
480 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
482 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
483 // we are in fully-young mode and there are free regions in the heap
485 double survivor_regions_evac_time =
486 predict_survivor_regions_evac_time();
488 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
489 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
490 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
491 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
492 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
493 + survivor_regions_evac_time;
495 // the result
496 size_t final_young_length = 0;
498 size_t init_free_regions =
499 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
501 // if we're still under the pause target...
502 if (base_time_ms <= target_pause_time_ms) {
503 // We make sure that the shortest young length that makes sense
504 // fits within the target pause time.
505 size_t min_young_length = 1;
507 if (predict_will_fit(min_young_length, base_time_ms,
508 init_free_regions, target_pause_time_ms)) {
509 // The shortest young length will fit within the target pause time;
510 // we'll now check whether the absolute maximum number of young
511 // regions will fit in the target pause time. If not, we'll do
512 // a binary search between min_young_length and max_young_length
513 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
514 size_t max_young_length = abs_max_young_length;
516 if (max_young_length > min_young_length) {
517 // Let's check if the initial max young length will fit within the
518 // target pause. If so then there is no need to search for a maximal
519 // young length - we'll return the initial maximum
521 if (predict_will_fit(max_young_length, base_time_ms,
522 init_free_regions, target_pause_time_ms)) {
523 // The maximum young length will satisfy the target pause time.
524 // We are done so set min young length to this maximum length.
525 // The code after the loop will then set final_young_length using
526 // the value cached in the minimum length.
527 min_young_length = max_young_length;
528 } else {
529 // The maximum possible number of young regions will not fit within
530 // the target pause time so let's search....
532 size_t diff = (max_young_length - min_young_length) / 2;
533 max_young_length = min_young_length + diff;
535 while (max_young_length > min_young_length) {
536 if (predict_will_fit(max_young_length, base_time_ms,
537 init_free_regions, target_pause_time_ms)) {
539 // The current max young length will fit within the target
540 // pause time. Note we do not exit the loop here. By setting
541 // min = max, and then increasing the max below means that
542 // we will continue searching for an upper bound in the
543 // range [max..max+diff]
544 min_young_length = max_young_length;
545 }
546 diff = (max_young_length - min_young_length) / 2;
547 max_young_length = min_young_length + diff;
548 }
549 // the above loop found a maximal young length that will fit
550 // within the target pause time.
551 }
552 assert(min_young_length <= abs_max_young_length, "just checking");
553 }
554 final_young_length = min_young_length;
555 }
556 }
557 // and we're done!
559 // we should have at least one region in the target young length
560 _young_list_target_length =
561 MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
563 // let's keep an eye of how long we spend on this calculation
564 // right now, I assume that we'll print it when we need it; we
565 // should really adde it to the breakdown of a pause
566 double end_time_sec = os::elapsedTime();
567 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
569 #ifdef TRACE_CALC_YOUNG_LENGTH
570 // leave this in for debugging, just in case
571 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
572 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
573 target_pause_time_ms,
574 _young_list_target_length
575 elapsed_time_ms,
576 full_young_gcs() ? "full" : "partial",
577 during_initial_mark_pause() ? " i-m" : "",
578 _in_marking_window,
579 _in_marking_window_im);
580 #endif // TRACE_CALC_YOUNG_LENGTH
582 if (_young_list_target_length < _young_list_min_length) {
583 // bummer; this means that, if we do a pause when the maximal
584 // length dictates, we'll violate the pause spacing target (the
585 // min length was calculate based on the application's current
586 // alloc rate);
588 // so, we have to bite the bullet, and allocate the minimum
589 // number. We'll violate our target, but we just can't meet it.
591 #ifdef TRACE_CALC_YOUNG_LENGTH
592 // leave this in for debugging, just in case
593 gclog_or_tty->print_cr("adjusted target length from "
594 SIZE_FORMAT " to " SIZE_FORMAT,
595 _young_list_target_length, _young_list_min_length);
596 #endif // TRACE_CALC_YOUNG_LENGTH
598 _young_list_target_length = _young_list_min_length;
599 }
600 } else {
601 // we are in a partially-young mode or we've run out of regions (due
602 // to evacuation failure)
604 #ifdef TRACE_CALC_YOUNG_LENGTH
605 // leave this in for debugging, just in case
606 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
607 _young_list_min_length);
608 #endif // TRACE_CALC_YOUNG_LENGTH
609 // we'll do the pause as soon as possible by choosing the minimum
610 _young_list_target_length =
611 MAX2(_young_list_min_length, (size_t) 1);
612 }
614 _rs_lengths_prediction = rs_lengths;
615 }
617 // This is used by: calculate_young_list_target_length(rs_length). It
618 // returns true iff:
619 // the predicted pause time for the given young list will not overflow
620 // the target pause time
621 // and:
622 // the predicted amount of surviving data will not overflow the
623 // the amount of free space available for survivor regions.
624 //
625 bool
626 G1CollectorPolicy::predict_will_fit(size_t young_length,
627 double base_time_ms,
628 size_t init_free_regions,
629 double target_pause_time_ms) {
631 if (young_length >= init_free_regions)
632 // end condition 1: not enough space for the young regions
633 return false;
635 double accum_surv_rate_adj = 0.0;
636 double accum_surv_rate =
637 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
639 size_t bytes_to_copy =
640 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
642 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
644 double young_other_time_ms =
645 predict_young_other_time_ms(young_length);
647 double pause_time_ms =
648 base_time_ms + copy_time_ms + young_other_time_ms;
650 if (pause_time_ms > target_pause_time_ms)
651 // end condition 2: over the target pause time
652 return false;
654 size_t free_bytes =
655 (init_free_regions - young_length) * HeapRegion::GrainBytes;
657 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
658 // end condition 3: out of to-space (conservatively)
659 return false;
661 // success!
662 return true;
663 }
665 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
666 double survivor_regions_evac_time = 0.0;
667 for (HeapRegion * r = _recorded_survivor_head;
668 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
669 r = r->get_next_young_region()) {
670 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
671 }
672 return survivor_regions_evac_time;
673 }
675 void G1CollectorPolicy::check_prediction_validity() {
676 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
678 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
679 if (rs_lengths > _rs_lengths_prediction) {
680 // add 10% to avoid having to recalculate often
681 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
682 calculate_young_list_target_length(rs_lengths_prediction);
683 }
684 }
686 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
687 bool is_tlab,
688 bool* gc_overhead_limit_was_exceeded) {
689 guarantee(false, "Not using this policy feature yet.");
690 return NULL;
691 }
693 // This method controls how a collector handles one or more
694 // of its generations being fully allocated.
695 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
696 bool is_tlab) {
697 guarantee(false, "Not using this policy feature yet.");
698 return NULL;
699 }
702 #ifndef PRODUCT
703 bool G1CollectorPolicy::verify_young_ages() {
704 HeapRegion* head = _g1->young_list()->first_region();
705 return
706 verify_young_ages(head, _short_lived_surv_rate_group);
707 // also call verify_young_ages on any additional surv rate groups
708 }
710 bool
711 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
712 SurvRateGroup *surv_rate_group) {
713 guarantee( surv_rate_group != NULL, "pre-condition" );
715 const char* name = surv_rate_group->name();
716 bool ret = true;
717 int prev_age = -1;
719 for (HeapRegion* curr = head;
720 curr != NULL;
721 curr = curr->get_next_young_region()) {
722 SurvRateGroup* group = curr->surv_rate_group();
723 if (group == NULL && !curr->is_survivor()) {
724 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
725 ret = false;
726 }
728 if (surv_rate_group == group) {
729 int age = curr->age_in_surv_rate_group();
731 if (age < 0) {
732 gclog_or_tty->print_cr("## %s: encountered negative age", name);
733 ret = false;
734 }
736 if (age <= prev_age) {
737 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
738 "(%d, %d)", name, age, prev_age);
739 ret = false;
740 }
741 prev_age = age;
742 }
743 }
745 return ret;
746 }
747 #endif // PRODUCT
749 void G1CollectorPolicy::record_full_collection_start() {
750 _cur_collection_start_sec = os::elapsedTime();
751 // Release the future to-space so that it is available for compaction into.
752 _g1->set_full_collection();
753 }
755 void G1CollectorPolicy::record_full_collection_end() {
756 // Consider this like a collection pause for the purposes of allocation
757 // since last pause.
758 double end_sec = os::elapsedTime();
759 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
760 double full_gc_time_ms = full_gc_time_sec * 1000.0;
762 _all_full_gc_times_ms->add(full_gc_time_ms);
764 update_recent_gc_times(end_sec, full_gc_time_ms);
766 _g1->clear_full_collection();
768 // "Nuke" the heuristics that control the fully/partially young GC
769 // transitions and make sure we start with fully young GCs after the
770 // Full GC.
771 set_full_young_gcs(true);
772 _last_full_young_gc = false;
773 _should_revert_to_full_young_gcs = false;
774 clear_initiate_conc_mark_if_possible();
775 clear_during_initial_mark_pause();
776 _known_garbage_bytes = 0;
777 _known_garbage_ratio = 0.0;
778 _in_marking_window = false;
779 _in_marking_window_im = false;
781 _short_lived_surv_rate_group->start_adding_regions();
782 // also call this on any additional surv rate groups
784 record_survivor_regions(0, NULL, NULL);
786 _prev_region_num_young = _region_num_young;
787 _prev_region_num_tenured = _region_num_tenured;
789 _free_regions_at_end_of_collection = _g1->free_regions();
790 // Reset survivors SurvRateGroup.
791 _survivor_surv_rate_group->reset();
792 calculate_young_list_min_length();
793 calculate_young_list_target_length();
794 }
796 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
797 _bytes_in_to_space_before_gc += bytes;
798 }
800 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
801 _bytes_in_to_space_after_gc += bytes;
802 }
804 void G1CollectorPolicy::record_stop_world_start() {
805 _stop_world_start = os::elapsedTime();
806 }
808 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
809 size_t start_used) {
810 if (PrintGCDetails) {
811 gclog_or_tty->stamp(PrintGCTimeStamps);
812 gclog_or_tty->print("[GC pause");
813 if (in_young_gc_mode())
814 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
815 }
817 assert(_g1->used_regions() == _g1->recalculate_used_regions(),
818 "sanity");
819 assert(_g1->used() == _g1->recalculate_used(), "sanity");
821 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
822 _all_stop_world_times_ms->add(s_w_t_ms);
823 _stop_world_start = 0.0;
825 _cur_collection_start_sec = start_time_sec;
826 _cur_collection_pause_used_at_start_bytes = start_used;
827 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
828 _pending_cards = _g1->pending_card_num();
829 _max_pending_cards = _g1->max_pending_card_num();
831 _bytes_in_to_space_before_gc = 0;
832 _bytes_in_to_space_after_gc = 0;
833 _bytes_in_collection_set_before_gc = 0;
835 #ifdef DEBUG
836 // initialise these to something well known so that we can spot
837 // if they are not set properly
839 for (int i = 0; i < _parallel_gc_threads; ++i) {
840 _par_last_gc_worker_start_times_ms[i] = -1234.0;
841 _par_last_ext_root_scan_times_ms[i] = -1234.0;
842 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
843 _par_last_update_rs_times_ms[i] = -1234.0;
844 _par_last_update_rs_processed_buffers[i] = -1234.0;
845 _par_last_scan_rs_times_ms[i] = -1234.0;
846 _par_last_scan_new_refs_times_ms[i] = -1234.0;
847 _par_last_obj_copy_times_ms[i] = -1234.0;
848 _par_last_termination_times_ms[i] = -1234.0;
849 _par_last_termination_attempts[i] = -1234.0;
850 _par_last_gc_worker_end_times_ms[i] = -1234.0;
851 }
852 #endif
854 for (int i = 0; i < _aux_num; ++i) {
855 _cur_aux_times_ms[i] = 0.0;
856 _cur_aux_times_set[i] = false;
857 }
859 _satb_drain_time_set = false;
860 _last_satb_drain_processed_buffers = -1;
862 if (in_young_gc_mode())
863 _last_young_gc_full = false;
865 // do that for any other surv rate groups
866 _short_lived_surv_rate_group->stop_adding_regions();
867 _survivors_age_table.clear();
869 assert( verify_young_ages(), "region age verification" );
870 }
872 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
873 _mark_closure_time_ms = mark_closure_time_ms;
874 }
876 void G1CollectorPolicy::record_concurrent_mark_init_start() {
877 _mark_init_start_sec = os::elapsedTime();
878 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
879 }
881 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
882 mark_init_elapsed_time_ms) {
883 _during_marking = true;
884 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
885 clear_during_initial_mark_pause();
886 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
887 }
889 void G1CollectorPolicy::record_concurrent_mark_init_end() {
890 double end_time_sec = os::elapsedTime();
891 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
892 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
893 record_concurrent_mark_init_end_pre(elapsed_time_ms);
895 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
896 }
898 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
899 _mark_remark_start_sec = os::elapsedTime();
900 _during_marking = false;
901 }
903 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
904 double end_time_sec = os::elapsedTime();
905 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
906 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
907 _cur_mark_stop_world_time_ms += elapsed_time_ms;
908 _prev_collection_pause_end_ms += elapsed_time_ms;
910 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
911 }
913 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
914 _mark_cleanup_start_sec = os::elapsedTime();
915 }
917 void
918 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
919 size_t max_live_bytes) {
920 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
921 record_concurrent_mark_cleanup_end_work2();
922 }
924 void
925 G1CollectorPolicy::
926 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
927 size_t max_live_bytes) {
928 if (_n_marks < 2) _n_marks++;
929 if (G1PolicyVerbose > 0)
930 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
931 " (of " SIZE_FORMAT " MB heap).",
932 max_live_bytes/M, _g1->capacity()/M);
933 }
935 // The important thing about this is that it includes "os::elapsedTime".
936 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
937 double end_time_sec = os::elapsedTime();
938 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
939 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
940 _cur_mark_stop_world_time_ms += elapsed_time_ms;
941 _prev_collection_pause_end_ms += elapsed_time_ms;
943 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
945 _num_markings++;
947 // We did a marking, so reset the "since_last_mark" variables.
948 double considerConcMarkCost = 1.0;
949 // If there are available processors, concurrent activity is free...
950 if (Threads::number_of_non_daemon_threads() * 2 <
951 os::active_processor_count()) {
952 considerConcMarkCost = 0.0;
953 }
954 _n_pauses_at_mark_end = _n_pauses;
955 _n_marks_since_last_pause++;
956 }
958 void
959 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
960 if (in_young_gc_mode()) {
961 _should_revert_to_full_young_gcs = false;
962 _last_full_young_gc = true;
963 _in_marking_window = false;
964 if (adaptive_young_list_length())
965 calculate_young_list_target_length();
966 }
967 }
969 void G1CollectorPolicy::record_concurrent_pause() {
970 if (_stop_world_start > 0.0) {
971 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
972 _all_yield_times_ms->add(yield_ms);
973 }
974 }
976 void G1CollectorPolicy::record_concurrent_pause_end() {
977 }
979 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
980 _cur_CH_strong_roots_end_sec = os::elapsedTime();
981 _cur_CH_strong_roots_dur_ms =
982 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
983 }
985 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
986 _cur_G1_strong_roots_end_sec = os::elapsedTime();
987 _cur_G1_strong_roots_dur_ms =
988 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
989 }
991 template<class T>
992 T sum_of(T* sum_arr, int start, int n, int N) {
993 T sum = (T)0;
994 for (int i = 0; i < n; i++) {
995 int j = (start + i) % N;
996 sum += sum_arr[j];
997 }
998 return sum;
999 }
1001 void G1CollectorPolicy::print_par_stats(int level,
1002 const char* str,
1003 double* data,
1004 bool summary) {
1005 double min = data[0], max = data[0];
1006 double total = 0.0;
1007 int j;
1008 for (j = 0; j < level; ++j)
1009 gclog_or_tty->print(" ");
1010 gclog_or_tty->print("[%s (ms):", str);
1011 for (uint i = 0; i < ParallelGCThreads; ++i) {
1012 double val = data[i];
1013 if (val < min)
1014 min = val;
1015 if (val > max)
1016 max = val;
1017 total += val;
1018 gclog_or_tty->print(" %3.1lf", val);
1019 }
1020 if (summary) {
1021 gclog_or_tty->print_cr("");
1022 double avg = total / (double) ParallelGCThreads;
1023 gclog_or_tty->print(" ");
1024 for (j = 0; j < level; ++j)
1025 gclog_or_tty->print(" ");
1026 gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
1027 avg, min, max);
1028 }
1029 gclog_or_tty->print_cr("]");
1030 }
1032 void G1CollectorPolicy::print_par_sizes(int level,
1033 const char* str,
1034 double* data,
1035 bool summary) {
1036 double min = data[0], max = data[0];
1037 double total = 0.0;
1038 int j;
1039 for (j = 0; j < level; ++j)
1040 gclog_or_tty->print(" ");
1041 gclog_or_tty->print("[%s :", str);
1042 for (uint i = 0; i < ParallelGCThreads; ++i) {
1043 double val = data[i];
1044 if (val < min)
1045 min = val;
1046 if (val > max)
1047 max = val;
1048 total += val;
1049 gclog_or_tty->print(" %d", (int) val);
1050 }
1051 if (summary) {
1052 gclog_or_tty->print_cr("");
1053 double avg = total / (double) ParallelGCThreads;
1054 gclog_or_tty->print(" ");
1055 for (j = 0; j < level; ++j)
1056 gclog_or_tty->print(" ");
1057 gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
1058 (int)total, (int)avg, (int)min, (int)max);
1059 }
1060 gclog_or_tty->print_cr("]");
1061 }
1063 void G1CollectorPolicy::print_stats (int level,
1064 const char* str,
1065 double value) {
1066 for (int j = 0; j < level; ++j)
1067 gclog_or_tty->print(" ");
1068 gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
1069 }
1071 void G1CollectorPolicy::print_stats (int level,
1072 const char* str,
1073 int value) {
1074 for (int j = 0; j < level; ++j)
1075 gclog_or_tty->print(" ");
1076 gclog_or_tty->print_cr("[%s: %d]", str, value);
1077 }
1079 double G1CollectorPolicy::avg_value (double* data) {
1080 if (ParallelGCThreads > 0) {
1081 double ret = 0.0;
1082 for (uint i = 0; i < ParallelGCThreads; ++i)
1083 ret += data[i];
1084 return ret / (double) ParallelGCThreads;
1085 } else {
1086 return data[0];
1087 }
1088 }
1090 double G1CollectorPolicy::max_value (double* data) {
1091 if (ParallelGCThreads > 0) {
1092 double ret = data[0];
1093 for (uint i = 1; i < ParallelGCThreads; ++i)
1094 if (data[i] > ret)
1095 ret = data[i];
1096 return ret;
1097 } else {
1098 return data[0];
1099 }
1100 }
1102 double G1CollectorPolicy::sum_of_values (double* data) {
1103 if (ParallelGCThreads > 0) {
1104 double sum = 0.0;
1105 for (uint i = 0; i < ParallelGCThreads; i++)
1106 sum += data[i];
1107 return sum;
1108 } else {
1109 return data[0];
1110 }
1111 }
1113 double G1CollectorPolicy::max_sum (double* data1,
1114 double* data2) {
1115 double ret = data1[0] + data2[0];
1117 if (ParallelGCThreads > 0) {
1118 for (uint i = 1; i < ParallelGCThreads; ++i) {
1119 double data = data1[i] + data2[i];
1120 if (data > ret)
1121 ret = data;
1122 }
1123 }
1124 return ret;
1125 }
1127 // Anything below that is considered to be zero
1128 #define MIN_TIMER_GRANULARITY 0.0000001
1130 void G1CollectorPolicy::record_collection_pause_end(bool abandoned) {
1131 double end_time_sec = os::elapsedTime();
1132 double elapsed_ms = _last_pause_time_ms;
1133 bool parallel = ParallelGCThreads > 0;
1134 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1135 size_t rs_size =
1136 _cur_collection_pause_used_regions_at_start - collection_set_size();
1137 size_t cur_used_bytes = _g1->used();
1138 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1139 bool last_pause_included_initial_mark = false;
1140 bool update_stats = !abandoned && !_g1->evacuation_failed();
1142 #ifndef PRODUCT
1143 if (G1YoungSurvRateVerbose) {
1144 gclog_or_tty->print_cr("");
1145 _short_lived_surv_rate_group->print();
1146 // do that for any other surv rate groups too
1147 }
1148 #endif // PRODUCT
1150 if (in_young_gc_mode()) {
1151 last_pause_included_initial_mark = during_initial_mark_pause();
1152 if (last_pause_included_initial_mark)
1153 record_concurrent_mark_init_end_pre(0.0);
1155 size_t min_used_targ =
1156 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1159 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1160 assert(!last_pause_included_initial_mark, "invariant");
1161 if (cur_used_bytes > min_used_targ &&
1162 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1163 assert(!during_initial_mark_pause(), "we should not see this here");
1165 // Note: this might have already been set, if during the last
1166 // pause we decided to start a cycle but at the beginning of
1167 // this pause we decided to postpone it. That's OK.
1168 set_initiate_conc_mark_if_possible();
1169 }
1170 }
1172 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1173 }
1175 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1176 end_time_sec, false);
1178 guarantee(_cur_collection_pause_used_regions_at_start >=
1179 collection_set_size(),
1180 "Negative RS size?");
1182 // This assert is exempted when we're doing parallel collection pauses,
1183 // because the fragmentation caused by the parallel GC allocation buffers
1184 // can lead to more memory being used during collection than was used
1185 // before. Best leave this out until the fragmentation problem is fixed.
1186 // Pauses in which evacuation failed can also lead to negative
1187 // collections, since no space is reclaimed from a region containing an
1188 // object whose evacuation failed.
1189 // Further, we're now always doing parallel collection. But I'm still
1190 // leaving this here as a placeholder for a more precise assertion later.
1191 // (DLD, 10/05.)
1192 assert((true || parallel) // Always using GC LABs now.
1193 || _g1->evacuation_failed()
1194 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1195 "Negative collection");
1197 size_t freed_bytes =
1198 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1199 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1201 double survival_fraction =
1202 (double)surviving_bytes/
1203 (double)_collection_set_bytes_used_before;
1205 _n_pauses++;
1207 if (update_stats) {
1208 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1209 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1210 _recent_evac_times_ms->add(evac_ms);
1211 _recent_pause_times_ms->add(elapsed_ms);
1213 _recent_rs_sizes->add(rs_size);
1215 // We exempt parallel collection from this check because Alloc Buffer
1216 // fragmentation can produce negative collections. Same with evac
1217 // failure.
1218 // Further, we're now always doing parallel collection. But I'm still
1219 // leaving this here as a placeholder for a more precise assertion later.
1220 // (DLD, 10/05.
1221 assert((true || parallel)
1222 || _g1->evacuation_failed()
1223 || surviving_bytes <= _collection_set_bytes_used_before,
1224 "Or else negative collection!");
1225 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1226 _recent_CS_bytes_surviving->add(surviving_bytes);
1228 // this is where we update the allocation rate of the application
1229 double app_time_ms =
1230 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1231 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1232 // This usually happens due to the timer not having the required
1233 // granularity. Some Linuxes are the usual culprits.
1234 // We'll just set it to something (arbitrarily) small.
1235 app_time_ms = 1.0;
1236 }
1237 size_t regions_allocated =
1238 (_region_num_young - _prev_region_num_young) +
1239 (_region_num_tenured - _prev_region_num_tenured);
1240 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1241 _alloc_rate_ms_seq->add(alloc_rate_ms);
1242 _prev_region_num_young = _region_num_young;
1243 _prev_region_num_tenured = _region_num_tenured;
1245 double interval_ms =
1246 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1247 update_recent_gc_times(end_time_sec, elapsed_ms);
1248 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1249 if (recent_avg_pause_time_ratio() < 0.0 ||
1250 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1251 #ifndef PRODUCT
1252 // Dump info to allow post-facto debugging
1253 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1254 gclog_or_tty->print_cr("-------------------------------------------");
1255 gclog_or_tty->print_cr("Recent GC Times (ms):");
1256 _recent_gc_times_ms->dump();
1257 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1258 _recent_prev_end_times_for_all_gcs_sec->dump();
1259 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1260 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1261 // In debug mode, terminate the JVM if the user wants to debug at this point.
1262 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1263 #endif // !PRODUCT
1264 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1265 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1266 if (_recent_avg_pause_time_ratio < 0.0) {
1267 _recent_avg_pause_time_ratio = 0.0;
1268 } else {
1269 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1270 _recent_avg_pause_time_ratio = 1.0;
1271 }
1272 }
1273 }
1275 if (G1PolicyVerbose > 1) {
1276 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1277 }
1279 PauseSummary* summary;
1280 if (abandoned) {
1281 summary = _abandoned_summary;
1282 } else {
1283 summary = _summary;
1284 }
1286 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1287 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1288 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1289 double update_rs_processed_buffers =
1290 sum_of_values(_par_last_update_rs_processed_buffers);
1291 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1292 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1293 double termination_time = avg_value(_par_last_termination_times_ms);
1295 double parallel_other_time = _cur_collection_par_time_ms -
1296 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1297 scan_rs_time + obj_copy_time + termination_time);
1298 if (update_stats) {
1299 MainBodySummary* body_summary = summary->main_body_summary();
1300 guarantee(body_summary != NULL, "should not be null!");
1302 if (_satb_drain_time_set)
1303 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1304 else
1305 body_summary->record_satb_drain_time_ms(0.0);
1306 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1307 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1308 body_summary->record_update_rs_time_ms(update_rs_time);
1309 body_summary->record_scan_rs_time_ms(scan_rs_time);
1310 body_summary->record_obj_copy_time_ms(obj_copy_time);
1311 if (parallel) {
1312 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1313 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1314 body_summary->record_termination_time_ms(termination_time);
1315 body_summary->record_parallel_other_time_ms(parallel_other_time);
1316 }
1317 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1318 }
1320 if (G1PolicyVerbose > 1) {
1321 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1322 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1323 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1324 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1325 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1326 " |RS|: " SIZE_FORMAT,
1327 elapsed_ms, recent_avg_time_for_pauses_ms(),
1328 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1329 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1330 evac_ms, recent_avg_time_for_evac_ms(),
1331 scan_rs_time,
1332 recent_avg_time_for_pauses_ms() -
1333 recent_avg_time_for_G1_strong_ms(),
1334 rs_size);
1336 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1337 " At end " SIZE_FORMAT "K\n"
1338 " garbage : " SIZE_FORMAT "K"
1339 " of " SIZE_FORMAT "K\n"
1340 " survival : %6.2f%% (%6.2f%% avg)",
1341 _cur_collection_pause_used_at_start_bytes/K,
1342 _g1->used()/K, freed_bytes/K,
1343 _collection_set_bytes_used_before/K,
1344 survival_fraction*100.0,
1345 recent_avg_survival_fraction()*100.0);
1346 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1347 recent_avg_pause_time_ratio() * 100.0);
1348 }
1350 double other_time_ms = elapsed_ms;
1352 if (!abandoned) {
1353 if (_satb_drain_time_set)
1354 other_time_ms -= _cur_satb_drain_time_ms;
1356 if (parallel)
1357 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1358 else
1359 other_time_ms -=
1360 update_rs_time +
1361 ext_root_scan_time + mark_stack_scan_time +
1362 scan_rs_time + obj_copy_time;
1363 }
1365 if (PrintGCDetails) {
1366 gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
1367 abandoned ? " (abandoned)" : "",
1368 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1369 elapsed_ms / 1000.0);
1371 if (!abandoned) {
1372 if (_satb_drain_time_set) {
1373 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1374 }
1375 if (_last_satb_drain_processed_buffers >= 0) {
1376 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1377 }
1378 if (parallel) {
1379 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1380 print_par_stats(2, "GC Worker Start Time",
1381 _par_last_gc_worker_start_times_ms, false);
1382 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1383 print_par_sizes(3, "Processed Buffers",
1384 _par_last_update_rs_processed_buffers, true);
1385 print_par_stats(2, "Ext Root Scanning",
1386 _par_last_ext_root_scan_times_ms);
1387 print_par_stats(2, "Mark Stack Scanning",
1388 _par_last_mark_stack_scan_times_ms);
1389 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1390 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1391 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1392 print_par_sizes(3, "Termination Attempts",
1393 _par_last_termination_attempts, true);
1394 print_par_stats(2, "GC Worker End Time",
1395 _par_last_gc_worker_end_times_ms, false);
1396 print_stats(2, "Other", parallel_other_time);
1397 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1398 } else {
1399 print_stats(1, "Update RS", update_rs_time);
1400 print_stats(2, "Processed Buffers",
1401 (int)update_rs_processed_buffers);
1402 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1403 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1404 print_stats(1, "Scan RS", scan_rs_time);
1405 print_stats(1, "Object Copying", obj_copy_time);
1406 }
1407 }
1408 #ifndef PRODUCT
1409 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1410 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1411 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1412 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1413 if (_num_cc_clears > 0) {
1414 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1415 }
1416 #endif
1417 print_stats(1, "Other", other_time_ms);
1418 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1420 for (int i = 0; i < _aux_num; ++i) {
1421 if (_cur_aux_times_set[i]) {
1422 char buffer[96];
1423 sprintf(buffer, "Aux%d", i);
1424 print_stats(1, buffer, _cur_aux_times_ms[i]);
1425 }
1426 }
1427 }
1428 if (PrintGCDetails)
1429 gclog_or_tty->print(" [");
1430 if (PrintGC || PrintGCDetails)
1431 _g1->print_size_transition(gclog_or_tty,
1432 _cur_collection_pause_used_at_start_bytes,
1433 _g1->used(), _g1->capacity());
1434 if (PrintGCDetails)
1435 gclog_or_tty->print_cr("]");
1437 _all_pause_times_ms->add(elapsed_ms);
1438 if (update_stats) {
1439 summary->record_total_time_ms(elapsed_ms);
1440 summary->record_other_time_ms(other_time_ms);
1441 }
1442 for (int i = 0; i < _aux_num; ++i)
1443 if (_cur_aux_times_set[i])
1444 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1446 // Reset marks-between-pauses counter.
1447 _n_marks_since_last_pause = 0;
1449 // Update the efficiency-since-mark vars.
1450 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1451 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1452 // This usually happens due to the timer not having the required
1453 // granularity. Some Linuxes are the usual culprits.
1454 // We'll just set it to something (arbitrarily) small.
1455 proc_ms = 1.0;
1456 }
1457 double cur_efficiency = (double) freed_bytes / proc_ms;
1459 bool new_in_marking_window = _in_marking_window;
1460 bool new_in_marking_window_im = false;
1461 if (during_initial_mark_pause()) {
1462 new_in_marking_window = true;
1463 new_in_marking_window_im = true;
1464 }
1466 if (in_young_gc_mode()) {
1467 if (_last_full_young_gc) {
1468 set_full_young_gcs(false);
1469 _last_full_young_gc = false;
1470 }
1472 if ( !_last_young_gc_full ) {
1473 if ( _should_revert_to_full_young_gcs ||
1474 _known_garbage_ratio < 0.05 ||
1475 (adaptive_young_list_length() &&
1476 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1477 set_full_young_gcs(true);
1478 }
1479 }
1480 _should_revert_to_full_young_gcs = false;
1482 if (_last_young_gc_full && !_during_marking)
1483 _young_gc_eff_seq->add(cur_efficiency);
1484 }
1486 _short_lived_surv_rate_group->start_adding_regions();
1487 // do that for any other surv rate groupsx
1489 // <NEW PREDICTION>
1491 if (update_stats) {
1492 double pause_time_ms = elapsed_ms;
1494 size_t diff = 0;
1495 if (_max_pending_cards >= _pending_cards)
1496 diff = _max_pending_cards - _pending_cards;
1497 _pending_card_diff_seq->add((double) diff);
1499 double cost_per_card_ms = 0.0;
1500 if (_pending_cards > 0) {
1501 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1502 _cost_per_card_ms_seq->add(cost_per_card_ms);
1503 }
1505 size_t cards_scanned = _g1->cards_scanned();
1507 double cost_per_entry_ms = 0.0;
1508 if (cards_scanned > 10) {
1509 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1510 if (_last_young_gc_full)
1511 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1512 else
1513 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1514 }
1516 if (_max_rs_lengths > 0) {
1517 double cards_per_entry_ratio =
1518 (double) cards_scanned / (double) _max_rs_lengths;
1519 if (_last_young_gc_full)
1520 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1521 else
1522 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1523 }
1525 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1526 if (rs_length_diff >= 0)
1527 _rs_length_diff_seq->add((double) rs_length_diff);
1529 size_t copied_bytes = surviving_bytes;
1530 double cost_per_byte_ms = 0.0;
1531 if (copied_bytes > 0) {
1532 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1533 if (_in_marking_window)
1534 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1535 else
1536 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1537 }
1539 double all_other_time_ms = pause_time_ms -
1540 (update_rs_time + scan_rs_time + obj_copy_time +
1541 _mark_closure_time_ms + termination_time);
1543 double young_other_time_ms = 0.0;
1544 if (_recorded_young_regions > 0) {
1545 young_other_time_ms =
1546 _recorded_young_cset_choice_time_ms +
1547 _recorded_young_free_cset_time_ms;
1548 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1549 (double) _recorded_young_regions);
1550 }
1551 double non_young_other_time_ms = 0.0;
1552 if (_recorded_non_young_regions > 0) {
1553 non_young_other_time_ms =
1554 _recorded_non_young_cset_choice_time_ms +
1555 _recorded_non_young_free_cset_time_ms;
1557 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1558 (double) _recorded_non_young_regions);
1559 }
1561 double constant_other_time_ms = all_other_time_ms -
1562 (young_other_time_ms + non_young_other_time_ms);
1563 _constant_other_time_ms_seq->add(constant_other_time_ms);
1565 double survival_ratio = 0.0;
1566 if (_bytes_in_collection_set_before_gc > 0) {
1567 survival_ratio = (double) bytes_in_to_space_during_gc() /
1568 (double) _bytes_in_collection_set_before_gc;
1569 }
1571 _pending_cards_seq->add((double) _pending_cards);
1572 _scanned_cards_seq->add((double) cards_scanned);
1573 _rs_lengths_seq->add((double) _max_rs_lengths);
1575 double expensive_region_limit_ms =
1576 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1577 if (expensive_region_limit_ms < 0.0) {
1578 // this means that the other time was predicted to be longer than
1579 // than the max pause time
1580 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1581 }
1582 _expensive_region_limit_ms = expensive_region_limit_ms;
1584 if (PREDICTIONS_VERBOSE) {
1585 gclog_or_tty->print_cr("");
1586 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1587 "REGIONS %d %d %d "
1588 "PENDING_CARDS %d %d "
1589 "CARDS_SCANNED %d %d "
1590 "RS_LENGTHS %d %d "
1591 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1592 "SURVIVAL_RATIO %1.6lf %1.6lf "
1593 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1594 "OTHER_YOUNG %1.6lf %1.6lf "
1595 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1596 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1597 "ELAPSED %1.6lf %1.6lf ",
1598 _cur_collection_start_sec,
1599 (!_last_young_gc_full) ? 2 :
1600 (last_pause_included_initial_mark) ? 1 : 0,
1601 _recorded_region_num,
1602 _recorded_young_regions,
1603 _recorded_non_young_regions,
1604 _predicted_pending_cards, _pending_cards,
1605 _predicted_cards_scanned, cards_scanned,
1606 _predicted_rs_lengths, _max_rs_lengths,
1607 _predicted_rs_update_time_ms, update_rs_time,
1608 _predicted_rs_scan_time_ms, scan_rs_time,
1609 _predicted_survival_ratio, survival_ratio,
1610 _predicted_object_copy_time_ms, obj_copy_time,
1611 _predicted_constant_other_time_ms, constant_other_time_ms,
1612 _predicted_young_other_time_ms, young_other_time_ms,
1613 _predicted_non_young_other_time_ms,
1614 non_young_other_time_ms,
1615 _vtime_diff_ms, termination_time,
1616 _predicted_pause_time_ms, elapsed_ms);
1617 }
1619 if (G1PolicyVerbose > 0) {
1620 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1621 _predicted_pause_time_ms,
1622 (_within_target) ? "within" : "outside",
1623 elapsed_ms);
1624 }
1626 }
1628 _in_marking_window = new_in_marking_window;
1629 _in_marking_window_im = new_in_marking_window_im;
1630 _free_regions_at_end_of_collection = _g1->free_regions();
1631 calculate_young_list_min_length();
1632 calculate_young_list_target_length();
1634 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1635 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1636 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1637 // </NEW PREDICTION>
1639 _target_pause_time_ms = -1.0;
1640 }
1642 // <NEW PREDICTION>
1644 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1645 double update_rs_processed_buffers,
1646 double goal_ms) {
1647 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1648 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1650 if (G1UseAdaptiveConcRefinement) {
1651 const int k_gy = 3, k_gr = 6;
1652 const double inc_k = 1.1, dec_k = 0.9;
1654 int g = cg1r->green_zone();
1655 if (update_rs_time > goal_ms) {
1656 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1657 } else {
1658 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1659 g = (int)MAX2(g * inc_k, g + 1.0);
1660 }
1661 }
1662 // Change the refinement threads params
1663 cg1r->set_green_zone(g);
1664 cg1r->set_yellow_zone(g * k_gy);
1665 cg1r->set_red_zone(g * k_gr);
1666 cg1r->reinitialize_threads();
1668 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1669 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1670 cg1r->yellow_zone());
1671 // Change the barrier params
1672 dcqs.set_process_completed_threshold(processing_threshold);
1673 dcqs.set_max_completed_queue(cg1r->red_zone());
1674 }
1676 int curr_queue_size = dcqs.completed_buffers_num();
1677 if (curr_queue_size >= cg1r->yellow_zone()) {
1678 dcqs.set_completed_queue_padding(curr_queue_size);
1679 } else {
1680 dcqs.set_completed_queue_padding(0);
1681 }
1682 dcqs.notify_if_necessary();
1683 }
1685 double
1686 G1CollectorPolicy::
1687 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1688 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1690 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1691 size_t young_num = g1h->young_list()->length();
1692 if (young_num == 0)
1693 return 0.0;
1695 young_num += adjustment;
1696 size_t pending_cards = predict_pending_cards();
1697 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1698 predict_rs_length_diff();
1699 size_t card_num;
1700 if (full_young_gcs())
1701 card_num = predict_young_card_num(rs_lengths);
1702 else
1703 card_num = predict_non_young_card_num(rs_lengths);
1704 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1705 double accum_yg_surv_rate =
1706 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1708 size_t bytes_to_copy =
1709 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1711 return
1712 predict_rs_update_time_ms(pending_cards) +
1713 predict_rs_scan_time_ms(card_num) +
1714 predict_object_copy_time_ms(bytes_to_copy) +
1715 predict_young_other_time_ms(young_num) +
1716 predict_constant_other_time_ms();
1717 }
1719 double
1720 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1721 size_t rs_length = predict_rs_length_diff();
1722 size_t card_num;
1723 if (full_young_gcs())
1724 card_num = predict_young_card_num(rs_length);
1725 else
1726 card_num = predict_non_young_card_num(rs_length);
1727 return predict_base_elapsed_time_ms(pending_cards, card_num);
1728 }
1730 double
1731 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1732 size_t scanned_cards) {
1733 return
1734 predict_rs_update_time_ms(pending_cards) +
1735 predict_rs_scan_time_ms(scanned_cards) +
1736 predict_constant_other_time_ms();
1737 }
1739 double
1740 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1741 bool young) {
1742 size_t rs_length = hr->rem_set()->occupied();
1743 size_t card_num;
1744 if (full_young_gcs())
1745 card_num = predict_young_card_num(rs_length);
1746 else
1747 card_num = predict_non_young_card_num(rs_length);
1748 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1750 double region_elapsed_time_ms =
1751 predict_rs_scan_time_ms(card_num) +
1752 predict_object_copy_time_ms(bytes_to_copy);
1754 if (young)
1755 region_elapsed_time_ms += predict_young_other_time_ms(1);
1756 else
1757 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1759 return region_elapsed_time_ms;
1760 }
1762 size_t
1763 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1764 size_t bytes_to_copy;
1765 if (hr->is_marked())
1766 bytes_to_copy = hr->max_live_bytes();
1767 else {
1768 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1769 "invariant" );
1770 int age = hr->age_in_surv_rate_group();
1771 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1772 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1773 }
1775 return bytes_to_copy;
1776 }
1778 void
1779 G1CollectorPolicy::start_recording_regions() {
1780 _recorded_rs_lengths = 0;
1781 _recorded_young_regions = 0;
1782 _recorded_non_young_regions = 0;
1784 #if PREDICTIONS_VERBOSE
1785 _recorded_marked_bytes = 0;
1786 _recorded_young_bytes = 0;
1787 _predicted_bytes_to_copy = 0;
1788 _predicted_rs_lengths = 0;
1789 _predicted_cards_scanned = 0;
1790 #endif // PREDICTIONS_VERBOSE
1791 }
1793 void
1794 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1795 #if PREDICTIONS_VERBOSE
1796 if (!young) {
1797 _recorded_marked_bytes += hr->max_live_bytes();
1798 }
1799 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1800 #endif // PREDICTIONS_VERBOSE
1802 size_t rs_length = hr->rem_set()->occupied();
1803 _recorded_rs_lengths += rs_length;
1804 }
1806 void
1807 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1808 assert(!hr->is_young(), "should not call this");
1809 ++_recorded_non_young_regions;
1810 record_cset_region_info(hr, false);
1811 }
1813 void
1814 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1815 _recorded_young_regions = n_regions;
1816 }
1818 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1819 #if PREDICTIONS_VERBOSE
1820 _recorded_young_bytes = bytes;
1821 #endif // PREDICTIONS_VERBOSE
1822 }
1824 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1825 _recorded_rs_lengths = rs_lengths;
1826 }
1828 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1829 _predicted_bytes_to_copy = bytes;
1830 }
1832 void
1833 G1CollectorPolicy::end_recording_regions() {
1834 // The _predicted_pause_time_ms field is referenced in code
1835 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1836 _predicted_pause_time_ms = -1.0;
1838 #if PREDICTIONS_VERBOSE
1839 _predicted_pending_cards = predict_pending_cards();
1840 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1841 if (full_young_gcs())
1842 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1843 else
1844 _predicted_cards_scanned +=
1845 predict_non_young_card_num(_predicted_rs_lengths);
1846 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1848 _predicted_rs_update_time_ms =
1849 predict_rs_update_time_ms(_g1->pending_card_num());
1850 _predicted_rs_scan_time_ms =
1851 predict_rs_scan_time_ms(_predicted_cards_scanned);
1852 _predicted_object_copy_time_ms =
1853 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1854 _predicted_constant_other_time_ms =
1855 predict_constant_other_time_ms();
1856 _predicted_young_other_time_ms =
1857 predict_young_other_time_ms(_recorded_young_regions);
1858 _predicted_non_young_other_time_ms =
1859 predict_non_young_other_time_ms(_recorded_non_young_regions);
1861 _predicted_pause_time_ms =
1862 _predicted_rs_update_time_ms +
1863 _predicted_rs_scan_time_ms +
1864 _predicted_object_copy_time_ms +
1865 _predicted_constant_other_time_ms +
1866 _predicted_young_other_time_ms +
1867 _predicted_non_young_other_time_ms;
1868 #endif // PREDICTIONS_VERBOSE
1869 }
1871 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1872 predicted_time_ms) {
1873 // I don't think we need to do this when in young GC mode since
1874 // marking will be initiated next time we hit the soft limit anyway...
1875 if (predicted_time_ms > _expensive_region_limit_ms) {
1876 if (!in_young_gc_mode()) {
1877 set_full_young_gcs(true);
1878 // We might want to do something different here. However,
1879 // right now we don't support the non-generational G1 mode
1880 // (and in fact we are planning to remove the associated code,
1881 // see CR 6814390). So, let's leave it as is and this will be
1882 // removed some time in the future
1883 ShouldNotReachHere();
1884 set_during_initial_mark_pause();
1885 } else
1886 // no point in doing another partial one
1887 _should_revert_to_full_young_gcs = true;
1888 }
1889 }
1891 // </NEW PREDICTION>
1894 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1895 double elapsed_ms) {
1896 _recent_gc_times_ms->add(elapsed_ms);
1897 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1898 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1899 }
1901 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1902 if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
1903 else return _recent_pause_times_ms->avg();
1904 }
1906 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
1907 if (_recent_CH_strong_roots_times_ms->num() == 0)
1908 return (double)MaxGCPauseMillis/3.0;
1909 else return _recent_CH_strong_roots_times_ms->avg();
1910 }
1912 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
1913 if (_recent_G1_strong_roots_times_ms->num() == 0)
1914 return (double)MaxGCPauseMillis/3.0;
1915 else return _recent_G1_strong_roots_times_ms->avg();
1916 }
1918 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
1919 if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
1920 else return _recent_evac_times_ms->avg();
1921 }
1923 int G1CollectorPolicy::number_of_recent_gcs() {
1924 assert(_recent_CH_strong_roots_times_ms->num() ==
1925 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
1926 assert(_recent_G1_strong_roots_times_ms->num() ==
1927 _recent_evac_times_ms->num(), "Sequence out of sync");
1928 assert(_recent_evac_times_ms->num() ==
1929 _recent_pause_times_ms->num(), "Sequence out of sync");
1930 assert(_recent_pause_times_ms->num() ==
1931 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1932 assert(_recent_CS_bytes_used_before->num() ==
1933 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1934 return _recent_pause_times_ms->num();
1935 }
1937 double G1CollectorPolicy::recent_avg_survival_fraction() {
1938 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1939 _recent_CS_bytes_used_before);
1940 }
1942 double G1CollectorPolicy::last_survival_fraction() {
1943 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1944 _recent_CS_bytes_used_before);
1945 }
1947 double
1948 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1949 TruncatedSeq* before) {
1950 assert(surviving->num() == before->num(), "Sequence out of sync");
1951 if (before->sum() > 0.0) {
1952 double recent_survival_rate = surviving->sum() / before->sum();
1953 // We exempt parallel collection from this check because Alloc Buffer
1954 // fragmentation can produce negative collections.
1955 // Further, we're now always doing parallel collection. But I'm still
1956 // leaving this here as a placeholder for a more precise assertion later.
1957 // (DLD, 10/05.)
1958 assert((true || ParallelGCThreads > 0) ||
1959 _g1->evacuation_failed() ||
1960 recent_survival_rate <= 1.0, "Or bad frac");
1961 return recent_survival_rate;
1962 } else {
1963 return 1.0; // Be conservative.
1964 }
1965 }
1967 double
1968 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
1969 TruncatedSeq* before) {
1970 assert(surviving->num() == before->num(), "Sequence out of sync");
1971 if (surviving->num() > 0 && before->last() > 0.0) {
1972 double last_survival_rate = surviving->last() / before->last();
1973 // We exempt parallel collection from this check because Alloc Buffer
1974 // fragmentation can produce negative collections.
1975 // Further, we're now always doing parallel collection. But I'm still
1976 // leaving this here as a placeholder for a more precise assertion later.
1977 // (DLD, 10/05.)
1978 assert((true || ParallelGCThreads > 0) ||
1979 last_survival_rate <= 1.0, "Or bad frac");
1980 return last_survival_rate;
1981 } else {
1982 return 1.0;
1983 }
1984 }
1986 static const int survival_min_obs = 5;
1987 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
1988 static const double min_survival_rate = 0.1;
1990 double
1991 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
1992 double latest) {
1993 double res = avg;
1994 if (number_of_recent_gcs() < survival_min_obs) {
1995 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
1996 }
1997 res = MAX2(res, latest);
1998 res = MAX2(res, min_survival_rate);
1999 // In the parallel case, LAB fragmentation can produce "negative
2000 // collections"; so can evac failure. Cap at 1.0
2001 res = MIN2(res, 1.0);
2002 return res;
2003 }
2005 size_t G1CollectorPolicy::expansion_amount() {
2006 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
2007 // We will double the existing space, or take
2008 // G1ExpandByPercentOfAvailable % of the available expansion
2009 // space, whichever is smaller, bounded below by a minimum
2010 // expansion (unless that's all that's left.)
2011 const size_t min_expand_bytes = 1*M;
2012 size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
2013 size_t committed_bytes = _g1->capacity();
2014 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2015 size_t expand_bytes;
2016 size_t expand_bytes_via_pct =
2017 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2018 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2019 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2020 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2021 if (G1PolicyVerbose > 1) {
2022 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2023 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2024 " Answer = %d.\n",
2025 recent_avg_pause_time_ratio(),
2026 byte_size_in_proper_unit(committed_bytes),
2027 proper_unit_for_byte_size(committed_bytes),
2028 byte_size_in_proper_unit(uncommitted_bytes),
2029 proper_unit_for_byte_size(uncommitted_bytes),
2030 byte_size_in_proper_unit(expand_bytes_via_pct),
2031 proper_unit_for_byte_size(expand_bytes_via_pct),
2032 byte_size_in_proper_unit(expand_bytes),
2033 proper_unit_for_byte_size(expand_bytes));
2034 }
2035 return expand_bytes;
2036 } else {
2037 return 0;
2038 }
2039 }
2041 void G1CollectorPolicy::note_start_of_mark_thread() {
2042 _mark_thread_startup_sec = os::elapsedTime();
2043 }
2045 class CountCSClosure: public HeapRegionClosure {
2046 G1CollectorPolicy* _g1_policy;
2047 public:
2048 CountCSClosure(G1CollectorPolicy* g1_policy) :
2049 _g1_policy(g1_policy) {}
2050 bool doHeapRegion(HeapRegion* r) {
2051 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2052 return false;
2053 }
2054 };
2056 void G1CollectorPolicy::count_CS_bytes_used() {
2057 CountCSClosure cs_closure(this);
2058 _g1->collection_set_iterate(&cs_closure);
2059 }
2061 static void print_indent(int level) {
2062 for (int j = 0; j < level+1; ++j)
2063 gclog_or_tty->print(" ");
2064 }
2066 void G1CollectorPolicy::print_summary (int level,
2067 const char* str,
2068 NumberSeq* seq) const {
2069 double sum = seq->sum();
2070 print_indent(level);
2071 gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2072 str, sum / 1000.0, seq->avg());
2073 }
2075 void G1CollectorPolicy::print_summary_sd (int level,
2076 const char* str,
2077 NumberSeq* seq) const {
2078 print_summary(level, str, seq);
2079 print_indent(level + 5);
2080 gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2081 seq->num(), seq->sd(), seq->maximum());
2082 }
2084 void G1CollectorPolicy::check_other_times(int level,
2085 NumberSeq* other_times_ms,
2086 NumberSeq* calc_other_times_ms) const {
2087 bool should_print = false;
2089 double max_sum = MAX2(fabs(other_times_ms->sum()),
2090 fabs(calc_other_times_ms->sum()));
2091 double min_sum = MIN2(fabs(other_times_ms->sum()),
2092 fabs(calc_other_times_ms->sum()));
2093 double sum_ratio = max_sum / min_sum;
2094 if (sum_ratio > 1.1) {
2095 should_print = true;
2096 print_indent(level + 1);
2097 gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2098 }
2100 double max_avg = MAX2(fabs(other_times_ms->avg()),
2101 fabs(calc_other_times_ms->avg()));
2102 double min_avg = MIN2(fabs(other_times_ms->avg()),
2103 fabs(calc_other_times_ms->avg()));
2104 double avg_ratio = max_avg / min_avg;
2105 if (avg_ratio > 1.1) {
2106 should_print = true;
2107 print_indent(level + 1);
2108 gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2109 }
2111 if (other_times_ms->sum() < -0.01) {
2112 print_indent(level + 1);
2113 gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2114 }
2116 if (other_times_ms->avg() < -0.01) {
2117 print_indent(level + 1);
2118 gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2119 }
2121 if (calc_other_times_ms->sum() < -0.01) {
2122 should_print = true;
2123 print_indent(level + 1);
2124 gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2125 }
2127 if (calc_other_times_ms->avg() < -0.01) {
2128 should_print = true;
2129 print_indent(level + 1);
2130 gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2131 }
2133 if (should_print)
2134 print_summary(level, "Other(Calc)", calc_other_times_ms);
2135 }
2137 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2138 bool parallel = ParallelGCThreads > 0;
2139 MainBodySummary* body_summary = summary->main_body_summary();
2140 if (summary->get_total_seq()->num() > 0) {
2141 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2142 if (body_summary != NULL) {
2143 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2144 if (parallel) {
2145 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2146 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2147 print_summary(2, "Ext Root Scanning",
2148 body_summary->get_ext_root_scan_seq());
2149 print_summary(2, "Mark Stack Scanning",
2150 body_summary->get_mark_stack_scan_seq());
2151 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2152 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2153 print_summary(2, "Termination", body_summary->get_termination_seq());
2154 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2155 {
2156 NumberSeq* other_parts[] = {
2157 body_summary->get_update_rs_seq(),
2158 body_summary->get_ext_root_scan_seq(),
2159 body_summary->get_mark_stack_scan_seq(),
2160 body_summary->get_scan_rs_seq(),
2161 body_summary->get_obj_copy_seq(),
2162 body_summary->get_termination_seq()
2163 };
2164 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2165 7, other_parts);
2166 check_other_times(2, body_summary->get_parallel_other_seq(),
2167 &calc_other_times_ms);
2168 }
2169 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2170 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2171 } else {
2172 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2173 print_summary(1, "Ext Root Scanning",
2174 body_summary->get_ext_root_scan_seq());
2175 print_summary(1, "Mark Stack Scanning",
2176 body_summary->get_mark_stack_scan_seq());
2177 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2178 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2179 }
2180 }
2181 print_summary(1, "Other", summary->get_other_seq());
2182 {
2183 NumberSeq calc_other_times_ms;
2184 if (body_summary != NULL) {
2185 // not abandoned
2186 if (parallel) {
2187 // parallel
2188 NumberSeq* other_parts[] = {
2189 body_summary->get_satb_drain_seq(),
2190 body_summary->get_parallel_seq(),
2191 body_summary->get_clear_ct_seq()
2192 };
2193 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2194 3, other_parts);
2195 } else {
2196 // serial
2197 NumberSeq* other_parts[] = {
2198 body_summary->get_satb_drain_seq(),
2199 body_summary->get_update_rs_seq(),
2200 body_summary->get_ext_root_scan_seq(),
2201 body_summary->get_mark_stack_scan_seq(),
2202 body_summary->get_scan_rs_seq(),
2203 body_summary->get_obj_copy_seq()
2204 };
2205 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2206 7, other_parts);
2207 }
2208 } else {
2209 // abandoned
2210 calc_other_times_ms = NumberSeq();
2211 }
2212 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2213 }
2214 } else {
2215 print_indent(0);
2216 gclog_or_tty->print_cr("none");
2217 }
2218 gclog_or_tty->print_cr("");
2219 }
2221 void
2222 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {
2223 bool printed = false;
2224 if (summary->get_total_seq()->num() > 0) {
2225 printed = true;
2226 print_summary(summary);
2227 }
2228 if (!printed) {
2229 print_indent(0);
2230 gclog_or_tty->print_cr("none");
2231 gclog_or_tty->print_cr("");
2232 }
2233 }
2235 void G1CollectorPolicy::print_tracing_info() const {
2236 if (TraceGen0Time) {
2237 gclog_or_tty->print_cr("ALL PAUSES");
2238 print_summary_sd(0, "Total", _all_pause_times_ms);
2239 gclog_or_tty->print_cr("");
2240 gclog_or_tty->print_cr("");
2241 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2242 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2243 gclog_or_tty->print_cr("");
2245 gclog_or_tty->print_cr("EVACUATION PAUSES");
2246 print_summary(_summary);
2248 gclog_or_tty->print_cr("ABANDONED PAUSES");
2249 print_abandoned_summary(_abandoned_summary);
2251 gclog_or_tty->print_cr("MISC");
2252 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2253 print_summary_sd(0, "Yields", _all_yield_times_ms);
2254 for (int i = 0; i < _aux_num; ++i) {
2255 if (_all_aux_times_ms[i].num() > 0) {
2256 char buffer[96];
2257 sprintf(buffer, "Aux%d", i);
2258 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2259 }
2260 }
2262 size_t all_region_num = _region_num_young + _region_num_tenured;
2263 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2264 "Tenured %8d (%6.2lf%%)",
2265 all_region_num,
2266 _region_num_young,
2267 (double) _region_num_young / (double) all_region_num * 100.0,
2268 _region_num_tenured,
2269 (double) _region_num_tenured / (double) all_region_num * 100.0);
2270 }
2271 if (TraceGen1Time) {
2272 if (_all_full_gc_times_ms->num() > 0) {
2273 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2274 _all_full_gc_times_ms->num(),
2275 _all_full_gc_times_ms->sum() / 1000.0);
2276 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2277 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2278 _all_full_gc_times_ms->sd(),
2279 _all_full_gc_times_ms->maximum());
2280 }
2281 }
2282 }
2284 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2285 #ifndef PRODUCT
2286 _short_lived_surv_rate_group->print_surv_rate_summary();
2287 // add this call for any other surv rate groups
2288 #endif // PRODUCT
2289 }
2291 bool
2292 G1CollectorPolicy::should_add_next_region_to_young_list() {
2293 assert(in_young_gc_mode(), "should be in young GC mode");
2294 bool ret;
2295 size_t young_list_length = _g1->young_list()->length();
2296 size_t young_list_max_length = _young_list_target_length;
2297 if (G1FixedEdenSize) {
2298 young_list_max_length -= _max_survivor_regions;
2299 }
2300 if (young_list_length < young_list_max_length) {
2301 ret = true;
2302 ++_region_num_young;
2303 } else {
2304 ret = false;
2305 ++_region_num_tenured;
2306 }
2308 return ret;
2309 }
2311 #ifndef PRODUCT
2312 // for debugging, bit of a hack...
2313 static char*
2314 region_num_to_mbs(int length) {
2315 static char buffer[64];
2316 double bytes = (double) (length * HeapRegion::GrainBytes);
2317 double mbs = bytes / (double) (1024 * 1024);
2318 sprintf(buffer, "%7.2lfMB", mbs);
2319 return buffer;
2320 }
2321 #endif // PRODUCT
2323 size_t G1CollectorPolicy::max_regions(int purpose) {
2324 switch (purpose) {
2325 case GCAllocForSurvived:
2326 return _max_survivor_regions;
2327 case GCAllocForTenured:
2328 return REGIONS_UNLIMITED;
2329 default:
2330 ShouldNotReachHere();
2331 return REGIONS_UNLIMITED;
2332 };
2333 }
2335 // Calculates survivor space parameters.
2336 void G1CollectorPolicy::calculate_survivors_policy()
2337 {
2338 if (G1FixedSurvivorSpaceSize == 0) {
2339 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2340 } else {
2341 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2342 }
2344 if (G1FixedTenuringThreshold) {
2345 _tenuring_threshold = MaxTenuringThreshold;
2346 } else {
2347 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2348 HeapRegion::GrainWords * _max_survivor_regions);
2349 }
2350 }
2352 bool
2353 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
2354 word_size) {
2355 assert(_g1->regions_accounted_for(), "Region leakage!");
2356 double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
2358 size_t young_list_length = _g1->young_list()->length();
2359 size_t young_list_max_length = _young_list_target_length;
2360 if (G1FixedEdenSize) {
2361 young_list_max_length -= _max_survivor_regions;
2362 }
2363 bool reached_target_length = young_list_length >= young_list_max_length;
2365 if (in_young_gc_mode()) {
2366 if (reached_target_length) {
2367 assert( young_list_length > 0 && _g1->young_list()->length() > 0,
2368 "invariant" );
2369 _target_pause_time_ms = max_pause_time_ms;
2370 return true;
2371 }
2372 } else {
2373 guarantee( false, "should not reach here" );
2374 }
2376 return false;
2377 }
2379 #ifndef PRODUCT
2380 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2381 CollectionSetChooser* _chooser;
2382 public:
2383 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2384 _chooser(chooser) {}
2386 bool doHeapRegion(HeapRegion* r) {
2387 if (!r->continuesHumongous()) {
2388 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2389 }
2390 return false;
2391 }
2392 };
2394 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2395 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2396 _g1->heap_region_iterate(&cl);
2397 return true;
2398 }
2399 #endif
2401 void
2402 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2403 // We are about to decide on whether this pause will be an
2404 // initial-mark pause.
2406 // First, during_initial_mark_pause() should not be already set. We
2407 // will set it here if we have to. However, it should be cleared by
2408 // the end of the pause (it's only set for the duration of an
2409 // initial-mark pause).
2410 assert(!during_initial_mark_pause(), "pre-condition");
2412 if (initiate_conc_mark_if_possible()) {
2413 // We had noticed on a previous pause that the heap occupancy has
2414 // gone over the initiating threshold and we should start a
2415 // concurrent marking cycle. So we might initiate one.
2417 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2418 if (!during_cycle) {
2419 // The concurrent marking thread is not "during a cycle", i.e.,
2420 // it has completed the last one. So we can go ahead and
2421 // initiate a new cycle.
2423 set_during_initial_mark_pause();
2425 // And we can now clear initiate_conc_mark_if_possible() as
2426 // we've already acted on it.
2427 clear_initiate_conc_mark_if_possible();
2428 } else {
2429 // The concurrent marking thread is still finishing up the
2430 // previous cycle. If we start one right now the two cycles
2431 // overlap. In particular, the concurrent marking thread might
2432 // be in the process of clearing the next marking bitmap (which
2433 // we will use for the next cycle if we start one). Starting a
2434 // cycle now will be bad given that parts of the marking
2435 // information might get cleared by the marking thread. And we
2436 // cannot wait for the marking thread to finish the cycle as it
2437 // periodically yields while clearing the next marking bitmap
2438 // and, if it's in a yield point, it's waiting for us to
2439 // finish. So, at this point we will not start a cycle and we'll
2440 // let the concurrent marking thread complete the last one.
2441 }
2442 }
2443 }
2445 void
2446 G1CollectorPolicy_BestRegionsFirst::
2447 record_collection_pause_start(double start_time_sec, size_t start_used) {
2448 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2449 }
2451 class NextNonCSElemFinder: public HeapRegionClosure {
2452 HeapRegion* _res;
2453 public:
2454 NextNonCSElemFinder(): _res(NULL) {}
2455 bool doHeapRegion(HeapRegion* r) {
2456 if (!r->in_collection_set()) {
2457 _res = r;
2458 return true;
2459 } else {
2460 return false;
2461 }
2462 }
2463 HeapRegion* res() { return _res; }
2464 };
2466 class KnownGarbageClosure: public HeapRegionClosure {
2467 CollectionSetChooser* _hrSorted;
2469 public:
2470 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2471 _hrSorted(hrSorted)
2472 {}
2474 bool doHeapRegion(HeapRegion* r) {
2475 // We only include humongous regions in collection
2476 // sets when concurrent mark shows that their contained object is
2477 // unreachable.
2479 // Do we have any marking information for this region?
2480 if (r->is_marked()) {
2481 // We don't include humongous regions in collection
2482 // sets because we collect them immediately at the end of a marking
2483 // cycle. We also don't include young regions because we *must*
2484 // include them in the next collection pause.
2485 if (!r->isHumongous() && !r->is_young()) {
2486 _hrSorted->addMarkedHeapRegion(r);
2487 }
2488 }
2489 return false;
2490 }
2491 };
2493 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2494 CollectionSetChooser* _hrSorted;
2495 jint _marked_regions_added;
2496 jint _chunk_size;
2497 jint _cur_chunk_idx;
2498 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2499 int _worker;
2500 int _invokes;
2502 void get_new_chunk() {
2503 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2504 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2505 }
2506 void add_region(HeapRegion* r) {
2507 if (_cur_chunk_idx == _cur_chunk_end) {
2508 get_new_chunk();
2509 }
2510 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2511 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2512 _marked_regions_added++;
2513 _cur_chunk_idx++;
2514 }
2516 public:
2517 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2518 jint chunk_size,
2519 int worker) :
2520 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2521 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2522 _invokes(0)
2523 {}
2525 bool doHeapRegion(HeapRegion* r) {
2526 // We only include humongous regions in collection
2527 // sets when concurrent mark shows that their contained object is
2528 // unreachable.
2529 _invokes++;
2531 // Do we have any marking information for this region?
2532 if (r->is_marked()) {
2533 // We don't include humongous regions in collection
2534 // sets because we collect them immediately at the end of a marking
2535 // cycle.
2536 // We also do not include young regions in collection sets
2537 if (!r->isHumongous() && !r->is_young()) {
2538 add_region(r);
2539 }
2540 }
2541 return false;
2542 }
2543 jint marked_regions_added() { return _marked_regions_added; }
2544 int invokes() { return _invokes; }
2545 };
2547 class ParKnownGarbageTask: public AbstractGangTask {
2548 CollectionSetChooser* _hrSorted;
2549 jint _chunk_size;
2550 G1CollectedHeap* _g1;
2551 public:
2552 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2553 AbstractGangTask("ParKnownGarbageTask"),
2554 _hrSorted(hrSorted), _chunk_size(chunk_size),
2555 _g1(G1CollectedHeap::heap())
2556 {}
2558 void work(int i) {
2559 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2560 // Back to zero for the claim value.
2561 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2562 HeapRegion::InitialClaimValue);
2563 jint regions_added = parKnownGarbageCl.marked_regions_added();
2564 _hrSorted->incNumMarkedHeapRegions(regions_added);
2565 if (G1PrintParCleanupStats) {
2566 gclog_or_tty->print(" Thread %d called %d times, added %d regions to list.\n",
2567 i, parKnownGarbageCl.invokes(), regions_added);
2568 }
2569 }
2570 };
2572 void
2573 G1CollectorPolicy_BestRegionsFirst::
2574 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2575 size_t max_live_bytes) {
2576 double start;
2577 if (G1PrintParCleanupStats) start = os::elapsedTime();
2578 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2580 _collectionSetChooser->clearMarkedHeapRegions();
2581 double clear_marked_end;
2582 if (G1PrintParCleanupStats) {
2583 clear_marked_end = os::elapsedTime();
2584 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2585 (clear_marked_end - start)*1000.0);
2586 }
2587 if (ParallelGCThreads > 0) {
2588 const size_t OverpartitionFactor = 4;
2589 const size_t MinWorkUnit = 8;
2590 const size_t WorkUnit =
2591 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2592 MinWorkUnit);
2593 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2594 WorkUnit);
2595 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2596 (int) WorkUnit);
2597 _g1->workers()->run_task(&parKnownGarbageTask);
2599 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2600 "sanity check");
2601 } else {
2602 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2603 _g1->heap_region_iterate(&knownGarbagecl);
2604 }
2605 double known_garbage_end;
2606 if (G1PrintParCleanupStats) {
2607 known_garbage_end = os::elapsedTime();
2608 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2609 (known_garbage_end - clear_marked_end)*1000.0);
2610 }
2611 _collectionSetChooser->sortMarkedHeapRegions();
2612 double sort_end;
2613 if (G1PrintParCleanupStats) {
2614 sort_end = os::elapsedTime();
2615 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2616 (sort_end - known_garbage_end)*1000.0);
2617 }
2619 record_concurrent_mark_cleanup_end_work2();
2620 double work2_end;
2621 if (G1PrintParCleanupStats) {
2622 work2_end = os::elapsedTime();
2623 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2624 (work2_end - sort_end)*1000.0);
2625 }
2626 }
2628 // Add the heap region at the head of the non-incremental collection set
2629 void G1CollectorPolicy::
2630 add_to_collection_set(HeapRegion* hr) {
2631 assert(_inc_cset_build_state == Active, "Precondition");
2632 assert(!hr->is_young(), "non-incremental add of young region");
2634 if (G1PrintHeapRegions) {
2635 gclog_or_tty->print_cr("added region to cset "
2636 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2637 "top "PTR_FORMAT", %s",
2638 hr->hrs_index(), hr->bottom(), hr->end(),
2639 hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
2640 }
2642 if (_g1->mark_in_progress())
2643 _g1->concurrent_mark()->registerCSetRegion(hr);
2645 assert(!hr->in_collection_set(), "should not already be in the CSet");
2646 hr->set_in_collection_set(true);
2647 hr->set_next_in_collection_set(_collection_set);
2648 _collection_set = hr;
2649 _collection_set_size++;
2650 _collection_set_bytes_used_before += hr->used();
2651 _g1->register_region_with_in_cset_fast_test(hr);
2652 }
2654 // Initialize the per-collection-set information
2655 void G1CollectorPolicy::start_incremental_cset_building() {
2656 assert(_inc_cset_build_state == Inactive, "Precondition");
2658 _inc_cset_head = NULL;
2659 _inc_cset_tail = NULL;
2660 _inc_cset_size = 0;
2661 _inc_cset_bytes_used_before = 0;
2663 if (in_young_gc_mode()) {
2664 _inc_cset_young_index = 0;
2665 }
2667 _inc_cset_max_finger = 0;
2668 _inc_cset_recorded_young_bytes = 0;
2669 _inc_cset_recorded_rs_lengths = 0;
2670 _inc_cset_predicted_elapsed_time_ms = 0;
2671 _inc_cset_predicted_bytes_to_copy = 0;
2672 _inc_cset_build_state = Active;
2673 }
2675 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2676 // This routine is used when:
2677 // * adding survivor regions to the incremental cset at the end of an
2678 // evacuation pause,
2679 // * adding the current allocation region to the incremental cset
2680 // when it is retired, and
2681 // * updating existing policy information for a region in the
2682 // incremental cset via young list RSet sampling.
2683 // Therefore this routine may be called at a safepoint by the
2684 // VM thread, or in-between safepoints by mutator threads (when
2685 // retiring the current allocation region) or a concurrent
2686 // refine thread (RSet sampling).
2688 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2689 size_t used_bytes = hr->used();
2691 _inc_cset_recorded_rs_lengths += rs_length;
2692 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2694 _inc_cset_bytes_used_before += used_bytes;
2696 // Cache the values we have added to the aggregated informtion
2697 // in the heap region in case we have to remove this region from
2698 // the incremental collection set, or it is updated by the
2699 // rset sampling code
2700 hr->set_recorded_rs_length(rs_length);
2701 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2703 #if PREDICTIONS_VERBOSE
2704 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2705 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2707 // Record the number of bytes used in this region
2708 _inc_cset_recorded_young_bytes += used_bytes;
2710 // Cache the values we have added to the aggregated informtion
2711 // in the heap region in case we have to remove this region from
2712 // the incremental collection set, or it is updated by the
2713 // rset sampling code
2714 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2715 #endif // PREDICTIONS_VERBOSE
2716 }
2718 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2719 // This routine is currently only called as part of the updating of
2720 // existing policy information for regions in the incremental cset that
2721 // is performed by the concurrent refine thread(s) as part of young list
2722 // RSet sampling. Therefore we should not be at a safepoint.
2724 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2725 assert(hr->is_young(), "it should be");
2727 size_t used_bytes = hr->used();
2728 size_t old_rs_length = hr->recorded_rs_length();
2729 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2731 // Subtract the old recorded/predicted policy information for
2732 // the given heap region from the collection set info.
2733 _inc_cset_recorded_rs_lengths -= old_rs_length;
2734 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2736 _inc_cset_bytes_used_before -= used_bytes;
2738 // Clear the values cached in the heap region
2739 hr->set_recorded_rs_length(0);
2740 hr->set_predicted_elapsed_time_ms(0);
2742 #if PREDICTIONS_VERBOSE
2743 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2744 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2746 // Subtract the number of bytes used in this region
2747 _inc_cset_recorded_young_bytes -= used_bytes;
2749 // Clear the values cached in the heap region
2750 hr->set_predicted_bytes_to_copy(0);
2751 #endif // PREDICTIONS_VERBOSE
2752 }
2754 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2755 // Update the collection set information that is dependent on the new RS length
2756 assert(hr->is_young(), "Precondition");
2758 remove_from_incremental_cset_info(hr);
2759 add_to_incremental_cset_info(hr, new_rs_length);
2760 }
2762 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2763 assert( hr->is_young(), "invariant");
2764 assert( hr->young_index_in_cset() == -1, "invariant" );
2765 assert(_inc_cset_build_state == Active, "Precondition");
2767 // We need to clear and set the cached recorded/cached collection set
2768 // information in the heap region here (before the region gets added
2769 // to the collection set). An individual heap region's cached values
2770 // are calculated, aggregated with the policy collection set info,
2771 // and cached in the heap region here (initially) and (subsequently)
2772 // by the Young List sampling code.
2774 size_t rs_length = hr->rem_set()->occupied();
2775 add_to_incremental_cset_info(hr, rs_length);
2777 HeapWord* hr_end = hr->end();
2778 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2780 assert(!hr->in_collection_set(), "invariant");
2781 hr->set_in_collection_set(true);
2782 assert( hr->next_in_collection_set() == NULL, "invariant");
2784 _inc_cset_size++;
2785 _g1->register_region_with_in_cset_fast_test(hr);
2787 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2788 ++_inc_cset_young_index;
2789 }
2791 // Add the region at the RHS of the incremental cset
2792 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2793 // We should only ever be appending survivors at the end of a pause
2794 assert( hr->is_survivor(), "Logic");
2796 // Do the 'common' stuff
2797 add_region_to_incremental_cset_common(hr);
2799 // Now add the region at the right hand side
2800 if (_inc_cset_tail == NULL) {
2801 assert(_inc_cset_head == NULL, "invariant");
2802 _inc_cset_head = hr;
2803 } else {
2804 _inc_cset_tail->set_next_in_collection_set(hr);
2805 }
2806 _inc_cset_tail = hr;
2808 if (G1PrintHeapRegions) {
2809 gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
2810 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2811 "top "PTR_FORMAT", young %s",
2812 hr->hrs_index(), hr->bottom(), hr->end(),
2813 hr->top(), (hr->is_young()) ? "YES" : "NO");
2814 }
2815 }
2817 // Add the region to the LHS of the incremental cset
2818 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2819 // Survivors should be added to the RHS at the end of a pause
2820 assert(!hr->is_survivor(), "Logic");
2822 // Do the 'common' stuff
2823 add_region_to_incremental_cset_common(hr);
2825 // Add the region at the left hand side
2826 hr->set_next_in_collection_set(_inc_cset_head);
2827 if (_inc_cset_head == NULL) {
2828 assert(_inc_cset_tail == NULL, "Invariant");
2829 _inc_cset_tail = hr;
2830 }
2831 _inc_cset_head = hr;
2833 if (G1PrintHeapRegions) {
2834 gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
2835 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2836 "top "PTR_FORMAT", young %s",
2837 hr->hrs_index(), hr->bottom(), hr->end(),
2838 hr->top(), (hr->is_young()) ? "YES" : "NO");
2839 }
2840 }
2842 #ifndef PRODUCT
2843 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2844 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2846 st->print_cr("\nCollection_set:");
2847 HeapRegion* csr = list_head;
2848 while (csr != NULL) {
2849 HeapRegion* next = csr->next_in_collection_set();
2850 assert(csr->in_collection_set(), "bad CS");
2851 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2852 "age: %4d, y: %d, surv: %d",
2853 csr->bottom(), csr->end(),
2854 csr->top(),
2855 csr->prev_top_at_mark_start(),
2856 csr->next_top_at_mark_start(),
2857 csr->top_at_conc_mark_count(),
2858 csr->age_in_surv_rate_group_cond(),
2859 csr->is_young(),
2860 csr->is_survivor());
2861 csr = next;
2862 }
2863 }
2864 #endif // !PRODUCT
2866 bool
2867 G1CollectorPolicy_BestRegionsFirst::choose_collection_set() {
2868 // Set this here - in case we're not doing young collections.
2869 double non_young_start_time_sec = os::elapsedTime();
2871 // The result that this routine will return. This will be set to
2872 // false if:
2873 // * we're doing a young or partially young collection and we
2874 // have added the youg regions to collection set, or
2875 // * we add old regions to the collection set.
2876 bool abandon_collection = true;
2878 start_recording_regions();
2880 guarantee(_target_pause_time_ms > -1.0
2881 NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
2882 "_target_pause_time_ms should have been set!");
2883 #ifndef PRODUCT
2884 if (_target_pause_time_ms <= -1.0) {
2885 assert(ScavengeALot && Universe::heap()->gc_cause() == GCCause::_scavenge_alot, "Error");
2886 _target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
2887 }
2888 #endif
2889 assert(_collection_set == NULL, "Precondition");
2891 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2892 double predicted_pause_time_ms = base_time_ms;
2894 double target_time_ms = _target_pause_time_ms;
2895 double time_remaining_ms = target_time_ms - base_time_ms;
2897 // the 10% and 50% values are arbitrary...
2898 if (time_remaining_ms < 0.10*target_time_ms) {
2899 time_remaining_ms = 0.50 * target_time_ms;
2900 _within_target = false;
2901 } else {
2902 _within_target = true;
2903 }
2905 // We figure out the number of bytes available for future to-space.
2906 // For new regions without marking information, we must assume the
2907 // worst-case of complete survival. If we have marking information for a
2908 // region, we can bound the amount of live data. We can add a number of
2909 // such regions, as long as the sum of the live data bounds does not
2910 // exceed the available evacuation space.
2911 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2913 size_t expansion_bytes =
2914 _g1->expansion_regions() * HeapRegion::GrainBytes;
2916 _collection_set_bytes_used_before = 0;
2917 _collection_set_size = 0;
2919 // Adjust for expansion and slop.
2920 max_live_bytes = max_live_bytes + expansion_bytes;
2922 assert(_g1->regions_accounted_for(), "Region leakage!");
2924 HeapRegion* hr;
2925 if (in_young_gc_mode()) {
2926 double young_start_time_sec = os::elapsedTime();
2928 if (G1PolicyVerbose > 0) {
2929 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2930 _g1->young_list()->length());
2931 }
2933 _young_cset_length = 0;
2934 _last_young_gc_full = full_young_gcs() ? true : false;
2936 if (_last_young_gc_full)
2937 ++_full_young_pause_num;
2938 else
2939 ++_partial_young_pause_num;
2941 // The young list is laid with the survivor regions from the previous
2942 // pause are appended to the RHS of the young list, i.e.
2943 // [Newly Young Regions ++ Survivors from last pause].
2945 hr = _g1->young_list()->first_survivor_region();
2946 while (hr != NULL) {
2947 assert(hr->is_survivor(), "badly formed young list");
2948 hr->set_young();
2949 hr = hr->get_next_young_region();
2950 }
2952 // Clear the fields that point to the survivor list - they are
2953 // all young now.
2954 _g1->young_list()->clear_survivors();
2956 if (_g1->mark_in_progress())
2957 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2959 _young_cset_length = _inc_cset_young_index;
2960 _collection_set = _inc_cset_head;
2961 _collection_set_size = _inc_cset_size;
2962 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2964 // For young regions in the collection set, we assume the worst
2965 // case of complete survival
2966 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2968 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2969 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2971 // The number of recorded young regions is the incremental
2972 // collection set's current size
2973 set_recorded_young_regions(_inc_cset_size);
2974 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2975 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2976 #if PREDICTIONS_VERBOSE
2977 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2978 #endif // PREDICTIONS_VERBOSE
2980 if (G1PolicyVerbose > 0) {
2981 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2982 _inc_cset_size);
2983 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2984 max_live_bytes/K);
2985 }
2987 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2988 if (_inc_cset_size > 0) {
2989 assert(_collection_set != NULL, "Invariant");
2990 abandon_collection = false;
2991 }
2993 double young_end_time_sec = os::elapsedTime();
2994 _recorded_young_cset_choice_time_ms =
2995 (young_end_time_sec - young_start_time_sec) * 1000.0;
2997 // We are doing young collections so reset this.
2998 non_young_start_time_sec = young_end_time_sec;
3000 // Note we can use either _collection_set_size or
3001 // _young_cset_length here
3002 if (_collection_set_size > 0 && _last_young_gc_full) {
3003 // don't bother adding more regions...
3004 goto choose_collection_set_end;
3005 }
3006 }
3008 if (!in_young_gc_mode() || !full_young_gcs()) {
3009 bool should_continue = true;
3010 NumberSeq seq;
3011 double avg_prediction = 100000000000000000.0; // something very large
3013 // Save the current size of the collection set to detect
3014 // if we actually added any old regions.
3015 size_t n_young_regions = _collection_set_size;
3017 do {
3018 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
3019 avg_prediction);
3020 if (hr != NULL) {
3021 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
3022 time_remaining_ms -= predicted_time_ms;
3023 predicted_pause_time_ms += predicted_time_ms;
3024 add_to_collection_set(hr);
3025 record_non_young_cset_region(hr);
3026 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
3027 if (G1PolicyVerbose > 0) {
3028 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
3029 max_live_bytes/K);
3030 }
3031 seq.add(predicted_time_ms);
3032 avg_prediction = seq.avg() + seq.sd();
3033 }
3034 should_continue =
3035 ( hr != NULL) &&
3036 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
3037 : _collection_set_size < _young_list_fixed_length );
3038 } while (should_continue);
3040 if (!adaptive_young_list_length() &&
3041 _collection_set_size < _young_list_fixed_length)
3042 _should_revert_to_full_young_gcs = true;
3044 if (_collection_set_size > n_young_regions) {
3045 // We actually added old regions to the collection set
3046 // so we are not abandoning this collection.
3047 abandon_collection = false;
3048 }
3049 }
3051 choose_collection_set_end:
3052 stop_incremental_cset_building();
3054 count_CS_bytes_used();
3056 end_recording_regions();
3058 double non_young_end_time_sec = os::elapsedTime();
3059 _recorded_non_young_cset_choice_time_ms =
3060 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3062 return abandon_collection;
3063 }
3065 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3066 G1CollectorPolicy::record_full_collection_end();
3067 _collectionSetChooser->updateAfterFullCollection();
3068 }
3070 void G1CollectorPolicy_BestRegionsFirst::
3071 expand_if_possible(size_t numRegions) {
3072 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3073 _g1->expand(expansion_bytes);
3074 }
3076 void G1CollectorPolicy_BestRegionsFirst::
3077 record_collection_pause_end(bool abandoned) {
3078 G1CollectorPolicy::record_collection_pause_end(abandoned);
3079 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3080 }