Wed, 02 Feb 2011 10:41:20 -0800
6923430: G1: assert(res != 0,"This should have worked.")
7007446: G1: expand the heap with a single step, not one region at a time
Summary: Changed G1CollectedHeap::expand() to expand the committed space by calling VirtualSpace::expand_by() once rather than for every region in the expansion amount. This allows the success or failure of the expansion to be determined before creating any heap regions. Introduced a develop flag G1ExitOnExpansionFailure (false by default) that, when true, will exit the VM if the expansion of the committed space fails. Finally G1CollectedHeap::expand() returns a status back to it's caller so that the caller knows whether to attempt the allocation.
Reviewed-by: brutisso, tonyp
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/shared/gcPolicyCounters.hpp"
33 #include "runtime/arguments.hpp"
34 #include "runtime/java.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "utilities/debug.hpp"
38 #define PREDICTIONS_VERBOSE 0
40 // <NEW PREDICTION>
42 // Different defaults for different number of GC threads
43 // They were chosen by running GCOld and SPECjbb on debris with different
44 // numbers of GC threads and choosing them based on the results
46 // all the same
47 static double rs_length_diff_defaults[] = {
48 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
49 };
51 static double cost_per_card_ms_defaults[] = {
52 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
53 };
55 // all the same
56 static double fully_young_cards_per_entry_ratio_defaults[] = {
57 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
58 };
60 static double cost_per_entry_ms_defaults[] = {
61 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
62 };
64 static double cost_per_byte_ms_defaults[] = {
65 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
66 };
68 // these should be pretty consistent
69 static double constant_other_time_ms_defaults[] = {
70 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
71 };
74 static double young_other_cost_per_region_ms_defaults[] = {
75 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
76 };
78 static double non_young_other_cost_per_region_ms_defaults[] = {
79 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
80 };
82 // </NEW PREDICTION>
84 G1CollectorPolicy::G1CollectorPolicy() :
85 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
86 ? ParallelGCThreads : 1),
89 _n_pauses(0),
90 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
91 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
92 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
93 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
94 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
95 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
96 _all_pause_times_ms(new NumberSeq()),
97 _stop_world_start(0.0),
98 _all_stop_world_times_ms(new NumberSeq()),
99 _all_yield_times_ms(new NumberSeq()),
101 _all_mod_union_times_ms(new NumberSeq()),
103 _summary(new Summary()),
105 #ifndef PRODUCT
106 _cur_clear_ct_time_ms(0.0),
107 _min_clear_cc_time_ms(-1.0),
108 _max_clear_cc_time_ms(-1.0),
109 _cur_clear_cc_time_ms(0.0),
110 _cum_clear_cc_time_ms(0.0),
111 _num_cc_clears(0L),
112 #endif
114 _region_num_young(0),
115 _region_num_tenured(0),
116 _prev_region_num_young(0),
117 _prev_region_num_tenured(0),
119 _aux_num(10),
120 _all_aux_times_ms(new NumberSeq[_aux_num]),
121 _cur_aux_start_times_ms(new double[_aux_num]),
122 _cur_aux_times_ms(new double[_aux_num]),
123 _cur_aux_times_set(new bool[_aux_num]),
125 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
126 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
127 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
129 // <NEW PREDICTION>
131 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
132 _prev_collection_pause_end_ms(0.0),
133 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
134 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
135 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
136 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
137 _partially_young_cards_per_entry_ratio_seq(
138 new TruncatedSeq(TruncatedSeqLength)),
139 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
140 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
141 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
142 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
143 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
144 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
145 _non_young_other_cost_per_region_ms_seq(
146 new TruncatedSeq(TruncatedSeqLength)),
148 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
149 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
150 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
152 _pause_time_target_ms((double) MaxGCPauseMillis),
154 // </NEW PREDICTION>
156 _in_young_gc_mode(false),
157 _full_young_gcs(true),
158 _full_young_pause_num(0),
159 _partial_young_pause_num(0),
161 _during_marking(false),
162 _in_marking_window(false),
163 _in_marking_window_im(false),
165 _known_garbage_ratio(0.0),
166 _known_garbage_bytes(0),
168 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
170 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
172 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
173 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
175 _recent_avg_pause_time_ratio(0.0),
176 _num_markings(0),
177 _n_marks(0),
178 _n_pauses_at_mark_end(0),
180 _all_full_gc_times_ms(new NumberSeq()),
182 // G1PausesBtwnConcMark defaults to -1
183 // so the hack is to do the cast QQQ FIXME
184 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
185 _n_marks_since_last_pause(0),
186 _initiate_conc_mark_if_possible(false),
187 _during_initial_mark_pause(false),
188 _should_revert_to_full_young_gcs(false),
189 _last_full_young_gc(false),
191 _prev_collection_pause_used_at_end_bytes(0),
193 _collection_set(NULL),
194 _collection_set_size(0),
195 _collection_set_bytes_used_before(0),
197 // Incremental CSet attributes
198 _inc_cset_build_state(Inactive),
199 _inc_cset_head(NULL),
200 _inc_cset_tail(NULL),
201 _inc_cset_size(0),
202 _inc_cset_young_index(0),
203 _inc_cset_bytes_used_before(0),
204 _inc_cset_max_finger(NULL),
205 _inc_cset_recorded_young_bytes(0),
206 _inc_cset_recorded_rs_lengths(0),
207 _inc_cset_predicted_elapsed_time_ms(0.0),
208 _inc_cset_predicted_bytes_to_copy(0),
210 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
211 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
212 #endif // _MSC_VER
214 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
215 G1YoungSurvRateNumRegionsSummary)),
216 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
217 G1YoungSurvRateNumRegionsSummary)),
218 // add here any more surv rate groups
219 _recorded_survivor_regions(0),
220 _recorded_survivor_head(NULL),
221 _recorded_survivor_tail(NULL),
222 _survivors_age_table(true),
224 _gc_overhead_perc(0.0)
226 {
227 // Set up the region size and associated fields. Given that the
228 // policy is created before the heap, we have to set this up here,
229 // so it's done as soon as possible.
230 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
231 HeapRegionRemSet::setup_remset_size();
233 // Verify PLAB sizes
234 const uint region_size = HeapRegion::GrainWords;
235 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
236 char buffer[128];
237 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
238 OldPLABSize > region_size ? "Old" : "Young", region_size);
239 vm_exit_during_initialization(buffer);
240 }
242 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
243 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
245 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
246 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
247 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
249 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
250 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
252 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
254 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
256 _par_last_termination_times_ms = new double[_parallel_gc_threads];
257 _par_last_termination_attempts = new double[_parallel_gc_threads];
258 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
260 // start conservatively
261 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
263 // <NEW PREDICTION>
265 int index;
266 if (ParallelGCThreads == 0)
267 index = 0;
268 else if (ParallelGCThreads > 8)
269 index = 7;
270 else
271 index = ParallelGCThreads - 1;
273 _pending_card_diff_seq->add(0.0);
274 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
275 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
276 _fully_young_cards_per_entry_ratio_seq->add(
277 fully_young_cards_per_entry_ratio_defaults[index]);
278 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
279 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
280 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
281 _young_other_cost_per_region_ms_seq->add(
282 young_other_cost_per_region_ms_defaults[index]);
283 _non_young_other_cost_per_region_ms_seq->add(
284 non_young_other_cost_per_region_ms_defaults[index]);
286 // </NEW PREDICTION>
288 // Below, we might need to calculate the pause time target based on
289 // the pause interval. When we do so we are going to give G1 maximum
290 // flexibility and allow it to do pauses when it needs to. So, we'll
291 // arrange that the pause interval to be pause time target + 1 to
292 // ensure that a) the pause time target is maximized with respect to
293 // the pause interval and b) we maintain the invariant that pause
294 // time target < pause interval. If the user does not want this
295 // maximum flexibility, they will have to set the pause interval
296 // explicitly.
298 // First make sure that, if either parameter is set, its value is
299 // reasonable.
300 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
301 if (MaxGCPauseMillis < 1) {
302 vm_exit_during_initialization("MaxGCPauseMillis should be "
303 "greater than 0");
304 }
305 }
306 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
307 if (GCPauseIntervalMillis < 1) {
308 vm_exit_during_initialization("GCPauseIntervalMillis should be "
309 "greater than 0");
310 }
311 }
313 // Then, if the pause time target parameter was not set, set it to
314 // the default value.
315 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
316 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
317 // The default pause time target in G1 is 200ms
318 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
319 } else {
320 // We do not allow the pause interval to be set without the
321 // pause time target
322 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
323 "without setting MaxGCPauseMillis");
324 }
325 }
327 // Then, if the interval parameter was not set, set it according to
328 // the pause time target (this will also deal with the case when the
329 // pause time target is the default value).
330 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
331 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
332 }
334 // Finally, make sure that the two parameters are consistent.
335 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
336 char buffer[256];
337 jio_snprintf(buffer, 256,
338 "MaxGCPauseMillis (%u) should be less than "
339 "GCPauseIntervalMillis (%u)",
340 MaxGCPauseMillis, GCPauseIntervalMillis);
341 vm_exit_during_initialization(buffer);
342 }
344 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
345 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
346 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
347 _sigma = (double) G1ConfidencePercent / 100.0;
349 // start conservatively (around 50ms is about right)
350 _concurrent_mark_init_times_ms->add(0.05);
351 _concurrent_mark_remark_times_ms->add(0.05);
352 _concurrent_mark_cleanup_times_ms->add(0.20);
353 _tenuring_threshold = MaxTenuringThreshold;
355 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
356 // fixed, then _max_survivor_regions will be calculated at
357 // calculate_young_list_target_length during initialization
358 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
360 assert(GCTimeRatio > 0,
361 "we should have set it to a default value set_g1_gc_flags() "
362 "if a user set it to 0");
363 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
365 initialize_all();
366 }
368 // Increment "i", mod "len"
369 static void inc_mod(int& i, int len) {
370 i++; if (i == len) i = 0;
371 }
373 void G1CollectorPolicy::initialize_flags() {
374 set_min_alignment(HeapRegion::GrainBytes);
375 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
376 if (SurvivorRatio < 1) {
377 vm_exit_during_initialization("Invalid survivor ratio specified");
378 }
379 CollectorPolicy::initialize_flags();
380 }
382 // The easiest way to deal with the parsing of the NewSize /
383 // MaxNewSize / etc. parameteres is to re-use the code in the
384 // TwoGenerationCollectorPolicy class. This is similar to what
385 // ParallelScavenge does with its GenerationSizer class (see
386 // ParallelScavengeHeap::initialize()). We might change this in the
387 // future, but it's a good start.
388 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
389 size_t size_to_region_num(size_t byte_size) {
390 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
391 }
393 public:
394 G1YoungGenSizer() {
395 initialize_flags();
396 initialize_size_info();
397 }
399 size_t min_young_region_num() {
400 return size_to_region_num(_min_gen0_size);
401 }
402 size_t initial_young_region_num() {
403 return size_to_region_num(_initial_gen0_size);
404 }
405 size_t max_young_region_num() {
406 return size_to_region_num(_max_gen0_size);
407 }
408 };
410 void G1CollectorPolicy::init() {
411 // Set aside an initial future to_space.
412 _g1 = G1CollectedHeap::heap();
414 assert(Heap_lock->owned_by_self(), "Locking discipline.");
416 initialize_gc_policy_counters();
418 if (G1Gen) {
419 _in_young_gc_mode = true;
421 G1YoungGenSizer sizer;
422 size_t initial_region_num = sizer.initial_young_region_num();
424 if (UseAdaptiveSizePolicy) {
425 set_adaptive_young_list_length(true);
426 _young_list_fixed_length = 0;
427 } else {
428 set_adaptive_young_list_length(false);
429 _young_list_fixed_length = initial_region_num;
430 }
431 _free_regions_at_end_of_collection = _g1->free_regions();
432 calculate_young_list_min_length();
433 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
434 calculate_young_list_target_length();
435 } else {
436 _young_list_fixed_length = 0;
437 _in_young_gc_mode = false;
438 }
440 // We may immediately start allocating regions and placing them on the
441 // collection set list. Initialize the per-collection set info
442 start_incremental_cset_building();
443 }
445 // Create the jstat counters for the policy.
446 void G1CollectorPolicy::initialize_gc_policy_counters()
447 {
448 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
449 }
451 void G1CollectorPolicy::calculate_young_list_min_length() {
452 _young_list_min_length = 0;
454 if (!adaptive_young_list_length())
455 return;
457 if (_alloc_rate_ms_seq->num() > 3) {
458 double now_sec = os::elapsedTime();
459 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
460 double alloc_rate_ms = predict_alloc_rate_ms();
461 size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
462 size_t current_region_num = _g1->young_list()->length();
463 _young_list_min_length = min_regions + current_region_num;
464 }
465 }
467 void G1CollectorPolicy::calculate_young_list_target_length() {
468 if (adaptive_young_list_length()) {
469 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
470 calculate_young_list_target_length(rs_lengths);
471 } else {
472 if (full_young_gcs())
473 _young_list_target_length = _young_list_fixed_length;
474 else
475 _young_list_target_length = _young_list_fixed_length / 2;
476 }
478 // Make sure we allow the application to allocate at least one
479 // region before we need to do a collection again.
480 size_t min_length = _g1->young_list()->length() + 1;
481 _young_list_target_length = MAX2(_young_list_target_length, min_length);
482 calculate_max_gc_locker_expansion();
483 calculate_survivors_policy();
484 }
486 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
487 guarantee( adaptive_young_list_length(), "pre-condition" );
488 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
490 double start_time_sec = os::elapsedTime();
491 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
492 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
493 size_t reserve_regions =
494 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
496 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
497 // we are in fully-young mode and there are free regions in the heap
499 double survivor_regions_evac_time =
500 predict_survivor_regions_evac_time();
502 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
503 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
504 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
505 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
506 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
507 + survivor_regions_evac_time;
509 // the result
510 size_t final_young_length = 0;
512 size_t init_free_regions =
513 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
515 // if we're still under the pause target...
516 if (base_time_ms <= target_pause_time_ms) {
517 // We make sure that the shortest young length that makes sense
518 // fits within the target pause time.
519 size_t min_young_length = 1;
521 if (predict_will_fit(min_young_length, base_time_ms,
522 init_free_regions, target_pause_time_ms)) {
523 // The shortest young length will fit within the target pause time;
524 // we'll now check whether the absolute maximum number of young
525 // regions will fit in the target pause time. If not, we'll do
526 // a binary search between min_young_length and max_young_length
527 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
528 size_t max_young_length = abs_max_young_length;
530 if (max_young_length > min_young_length) {
531 // Let's check if the initial max young length will fit within the
532 // target pause. If so then there is no need to search for a maximal
533 // young length - we'll return the initial maximum
535 if (predict_will_fit(max_young_length, base_time_ms,
536 init_free_regions, target_pause_time_ms)) {
537 // The maximum young length will satisfy the target pause time.
538 // We are done so set min young length to this maximum length.
539 // The code after the loop will then set final_young_length using
540 // the value cached in the minimum length.
541 min_young_length = max_young_length;
542 } else {
543 // The maximum possible number of young regions will not fit within
544 // the target pause time so let's search....
546 size_t diff = (max_young_length - min_young_length) / 2;
547 max_young_length = min_young_length + diff;
549 while (max_young_length > min_young_length) {
550 if (predict_will_fit(max_young_length, base_time_ms,
551 init_free_regions, target_pause_time_ms)) {
553 // The current max young length will fit within the target
554 // pause time. Note we do not exit the loop here. By setting
555 // min = max, and then increasing the max below means that
556 // we will continue searching for an upper bound in the
557 // range [max..max+diff]
558 min_young_length = max_young_length;
559 }
560 diff = (max_young_length - min_young_length) / 2;
561 max_young_length = min_young_length + diff;
562 }
563 // the above loop found a maximal young length that will fit
564 // within the target pause time.
565 }
566 assert(min_young_length <= abs_max_young_length, "just checking");
567 }
568 final_young_length = min_young_length;
569 }
570 }
571 // and we're done!
573 // we should have at least one region in the target young length
574 _young_list_target_length =
575 final_young_length + _recorded_survivor_regions;
577 // let's keep an eye of how long we spend on this calculation
578 // right now, I assume that we'll print it when we need it; we
579 // should really adde it to the breakdown of a pause
580 double end_time_sec = os::elapsedTime();
581 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
583 #ifdef TRACE_CALC_YOUNG_LENGTH
584 // leave this in for debugging, just in case
585 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
586 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
587 target_pause_time_ms,
588 _young_list_target_length
589 elapsed_time_ms,
590 full_young_gcs() ? "full" : "partial",
591 during_initial_mark_pause() ? " i-m" : "",
592 _in_marking_window,
593 _in_marking_window_im);
594 #endif // TRACE_CALC_YOUNG_LENGTH
596 if (_young_list_target_length < _young_list_min_length) {
597 // bummer; this means that, if we do a pause when the maximal
598 // length dictates, we'll violate the pause spacing target (the
599 // min length was calculate based on the application's current
600 // alloc rate);
602 // so, we have to bite the bullet, and allocate the minimum
603 // number. We'll violate our target, but we just can't meet it.
605 #ifdef TRACE_CALC_YOUNG_LENGTH
606 // leave this in for debugging, just in case
607 gclog_or_tty->print_cr("adjusted target length from "
608 SIZE_FORMAT " to " SIZE_FORMAT,
609 _young_list_target_length, _young_list_min_length);
610 #endif // TRACE_CALC_YOUNG_LENGTH
612 _young_list_target_length = _young_list_min_length;
613 }
614 } else {
615 // we are in a partially-young mode or we've run out of regions (due
616 // to evacuation failure)
618 #ifdef TRACE_CALC_YOUNG_LENGTH
619 // leave this in for debugging, just in case
620 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
621 _young_list_min_length);
622 #endif // TRACE_CALC_YOUNG_LENGTH
623 // we'll do the pause as soon as possible by choosing the minimum
624 _young_list_target_length = _young_list_min_length;
625 }
627 _rs_lengths_prediction = rs_lengths;
628 }
630 // This is used by: calculate_young_list_target_length(rs_length). It
631 // returns true iff:
632 // the predicted pause time for the given young list will not overflow
633 // the target pause time
634 // and:
635 // the predicted amount of surviving data will not overflow the
636 // the amount of free space available for survivor regions.
637 //
638 bool
639 G1CollectorPolicy::predict_will_fit(size_t young_length,
640 double base_time_ms,
641 size_t init_free_regions,
642 double target_pause_time_ms) {
644 if (young_length >= init_free_regions)
645 // end condition 1: not enough space for the young regions
646 return false;
648 double accum_surv_rate_adj = 0.0;
649 double accum_surv_rate =
650 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
652 size_t bytes_to_copy =
653 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
655 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
657 double young_other_time_ms =
658 predict_young_other_time_ms(young_length);
660 double pause_time_ms =
661 base_time_ms + copy_time_ms + young_other_time_ms;
663 if (pause_time_ms > target_pause_time_ms)
664 // end condition 2: over the target pause time
665 return false;
667 size_t free_bytes =
668 (init_free_regions - young_length) * HeapRegion::GrainBytes;
670 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
671 // end condition 3: out of to-space (conservatively)
672 return false;
674 // success!
675 return true;
676 }
678 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
679 double survivor_regions_evac_time = 0.0;
680 for (HeapRegion * r = _recorded_survivor_head;
681 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
682 r = r->get_next_young_region()) {
683 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
684 }
685 return survivor_regions_evac_time;
686 }
688 void G1CollectorPolicy::check_prediction_validity() {
689 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
691 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
692 if (rs_lengths > _rs_lengths_prediction) {
693 // add 10% to avoid having to recalculate often
694 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
695 calculate_young_list_target_length(rs_lengths_prediction);
696 }
697 }
699 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
700 bool is_tlab,
701 bool* gc_overhead_limit_was_exceeded) {
702 guarantee(false, "Not using this policy feature yet.");
703 return NULL;
704 }
706 // This method controls how a collector handles one or more
707 // of its generations being fully allocated.
708 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
709 bool is_tlab) {
710 guarantee(false, "Not using this policy feature yet.");
711 return NULL;
712 }
715 #ifndef PRODUCT
716 bool G1CollectorPolicy::verify_young_ages() {
717 HeapRegion* head = _g1->young_list()->first_region();
718 return
719 verify_young_ages(head, _short_lived_surv_rate_group);
720 // also call verify_young_ages on any additional surv rate groups
721 }
723 bool
724 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
725 SurvRateGroup *surv_rate_group) {
726 guarantee( surv_rate_group != NULL, "pre-condition" );
728 const char* name = surv_rate_group->name();
729 bool ret = true;
730 int prev_age = -1;
732 for (HeapRegion* curr = head;
733 curr != NULL;
734 curr = curr->get_next_young_region()) {
735 SurvRateGroup* group = curr->surv_rate_group();
736 if (group == NULL && !curr->is_survivor()) {
737 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
738 ret = false;
739 }
741 if (surv_rate_group == group) {
742 int age = curr->age_in_surv_rate_group();
744 if (age < 0) {
745 gclog_or_tty->print_cr("## %s: encountered negative age", name);
746 ret = false;
747 }
749 if (age <= prev_age) {
750 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
751 "(%d, %d)", name, age, prev_age);
752 ret = false;
753 }
754 prev_age = age;
755 }
756 }
758 return ret;
759 }
760 #endif // PRODUCT
762 void G1CollectorPolicy::record_full_collection_start() {
763 _cur_collection_start_sec = os::elapsedTime();
764 // Release the future to-space so that it is available for compaction into.
765 _g1->set_full_collection();
766 }
768 void G1CollectorPolicy::record_full_collection_end() {
769 // Consider this like a collection pause for the purposes of allocation
770 // since last pause.
771 double end_sec = os::elapsedTime();
772 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
773 double full_gc_time_ms = full_gc_time_sec * 1000.0;
775 _all_full_gc_times_ms->add(full_gc_time_ms);
777 update_recent_gc_times(end_sec, full_gc_time_ms);
779 _g1->clear_full_collection();
781 // "Nuke" the heuristics that control the fully/partially young GC
782 // transitions and make sure we start with fully young GCs after the
783 // Full GC.
784 set_full_young_gcs(true);
785 _last_full_young_gc = false;
786 _should_revert_to_full_young_gcs = false;
787 clear_initiate_conc_mark_if_possible();
788 clear_during_initial_mark_pause();
789 _known_garbage_bytes = 0;
790 _known_garbage_ratio = 0.0;
791 _in_marking_window = false;
792 _in_marking_window_im = false;
794 _short_lived_surv_rate_group->start_adding_regions();
795 // also call this on any additional surv rate groups
797 record_survivor_regions(0, NULL, NULL);
799 _prev_region_num_young = _region_num_young;
800 _prev_region_num_tenured = _region_num_tenured;
802 _free_regions_at_end_of_collection = _g1->free_regions();
803 // Reset survivors SurvRateGroup.
804 _survivor_surv_rate_group->reset();
805 calculate_young_list_min_length();
806 calculate_young_list_target_length();
807 }
809 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
810 _bytes_in_to_space_before_gc += bytes;
811 }
813 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
814 _bytes_in_to_space_after_gc += bytes;
815 }
817 void G1CollectorPolicy::record_stop_world_start() {
818 _stop_world_start = os::elapsedTime();
819 }
821 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
822 size_t start_used) {
823 if (PrintGCDetails) {
824 gclog_or_tty->stamp(PrintGCTimeStamps);
825 gclog_or_tty->print("[GC pause");
826 if (in_young_gc_mode())
827 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
828 }
830 assert(_g1->used() == _g1->recalculate_used(),
831 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
832 _g1->used(), _g1->recalculate_used()));
834 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
835 _all_stop_world_times_ms->add(s_w_t_ms);
836 _stop_world_start = 0.0;
838 _cur_collection_start_sec = start_time_sec;
839 _cur_collection_pause_used_at_start_bytes = start_used;
840 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
841 _pending_cards = _g1->pending_card_num();
842 _max_pending_cards = _g1->max_pending_card_num();
844 _bytes_in_to_space_before_gc = 0;
845 _bytes_in_to_space_after_gc = 0;
846 _bytes_in_collection_set_before_gc = 0;
848 #ifdef DEBUG
849 // initialise these to something well known so that we can spot
850 // if they are not set properly
852 for (int i = 0; i < _parallel_gc_threads; ++i) {
853 _par_last_gc_worker_start_times_ms[i] = -1234.0;
854 _par_last_ext_root_scan_times_ms[i] = -1234.0;
855 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
856 _par_last_update_rs_times_ms[i] = -1234.0;
857 _par_last_update_rs_processed_buffers[i] = -1234.0;
858 _par_last_scan_rs_times_ms[i] = -1234.0;
859 _par_last_obj_copy_times_ms[i] = -1234.0;
860 _par_last_termination_times_ms[i] = -1234.0;
861 _par_last_termination_attempts[i] = -1234.0;
862 _par_last_gc_worker_end_times_ms[i] = -1234.0;
863 }
864 #endif
866 for (int i = 0; i < _aux_num; ++i) {
867 _cur_aux_times_ms[i] = 0.0;
868 _cur_aux_times_set[i] = false;
869 }
871 _satb_drain_time_set = false;
872 _last_satb_drain_processed_buffers = -1;
874 if (in_young_gc_mode())
875 _last_young_gc_full = false;
877 // do that for any other surv rate groups
878 _short_lived_surv_rate_group->stop_adding_regions();
879 _survivors_age_table.clear();
881 assert( verify_young_ages(), "region age verification" );
882 }
884 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
885 _mark_closure_time_ms = mark_closure_time_ms;
886 }
888 void G1CollectorPolicy::record_concurrent_mark_init_start() {
889 _mark_init_start_sec = os::elapsedTime();
890 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
891 }
893 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
894 mark_init_elapsed_time_ms) {
895 _during_marking = true;
896 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
897 clear_during_initial_mark_pause();
898 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
899 }
901 void G1CollectorPolicy::record_concurrent_mark_init_end() {
902 double end_time_sec = os::elapsedTime();
903 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
904 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
905 record_concurrent_mark_init_end_pre(elapsed_time_ms);
907 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
908 }
910 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
911 _mark_remark_start_sec = os::elapsedTime();
912 _during_marking = false;
913 }
915 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
916 double end_time_sec = os::elapsedTime();
917 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
918 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
919 _cur_mark_stop_world_time_ms += elapsed_time_ms;
920 _prev_collection_pause_end_ms += elapsed_time_ms;
922 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
923 }
925 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
926 _mark_cleanup_start_sec = os::elapsedTime();
927 }
929 void
930 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
931 size_t max_live_bytes) {
932 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
933 record_concurrent_mark_cleanup_end_work2();
934 }
936 void
937 G1CollectorPolicy::
938 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
939 size_t max_live_bytes) {
940 if (_n_marks < 2) _n_marks++;
941 if (G1PolicyVerbose > 0)
942 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
943 " (of " SIZE_FORMAT " MB heap).",
944 max_live_bytes/M, _g1->capacity()/M);
945 }
947 // The important thing about this is that it includes "os::elapsedTime".
948 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
949 double end_time_sec = os::elapsedTime();
950 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
951 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
952 _cur_mark_stop_world_time_ms += elapsed_time_ms;
953 _prev_collection_pause_end_ms += elapsed_time_ms;
955 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
957 _num_markings++;
959 // We did a marking, so reset the "since_last_mark" variables.
960 double considerConcMarkCost = 1.0;
961 // If there are available processors, concurrent activity is free...
962 if (Threads::number_of_non_daemon_threads() * 2 <
963 os::active_processor_count()) {
964 considerConcMarkCost = 0.0;
965 }
966 _n_pauses_at_mark_end = _n_pauses;
967 _n_marks_since_last_pause++;
968 }
970 void
971 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
972 if (in_young_gc_mode()) {
973 _should_revert_to_full_young_gcs = false;
974 _last_full_young_gc = true;
975 _in_marking_window = false;
976 if (adaptive_young_list_length())
977 calculate_young_list_target_length();
978 }
979 }
981 void G1CollectorPolicy::record_concurrent_pause() {
982 if (_stop_world_start > 0.0) {
983 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
984 _all_yield_times_ms->add(yield_ms);
985 }
986 }
988 void G1CollectorPolicy::record_concurrent_pause_end() {
989 }
991 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
992 _cur_CH_strong_roots_end_sec = os::elapsedTime();
993 _cur_CH_strong_roots_dur_ms =
994 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
995 }
997 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
998 _cur_G1_strong_roots_end_sec = os::elapsedTime();
999 _cur_G1_strong_roots_dur_ms =
1000 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
1001 }
1003 template<class T>
1004 T sum_of(T* sum_arr, int start, int n, int N) {
1005 T sum = (T)0;
1006 for (int i = 0; i < n; i++) {
1007 int j = (start + i) % N;
1008 sum += sum_arr[j];
1009 }
1010 return sum;
1011 }
1013 void G1CollectorPolicy::print_par_stats(int level,
1014 const char* str,
1015 double* data,
1016 bool summary) {
1017 double min = data[0], max = data[0];
1018 double total = 0.0;
1019 int j;
1020 for (j = 0; j < level; ++j)
1021 gclog_or_tty->print(" ");
1022 gclog_or_tty->print("[%s (ms):", str);
1023 for (uint i = 0; i < ParallelGCThreads; ++i) {
1024 double val = data[i];
1025 if (val < min)
1026 min = val;
1027 if (val > max)
1028 max = val;
1029 total += val;
1030 gclog_or_tty->print(" %3.1lf", val);
1031 }
1032 if (summary) {
1033 gclog_or_tty->print_cr("");
1034 double avg = total / (double) ParallelGCThreads;
1035 gclog_or_tty->print(" ");
1036 for (j = 0; j < level; ++j)
1037 gclog_or_tty->print(" ");
1038 gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
1039 avg, min, max);
1040 }
1041 gclog_or_tty->print_cr("]");
1042 }
1044 void G1CollectorPolicy::print_par_sizes(int level,
1045 const char* str,
1046 double* data,
1047 bool summary) {
1048 double min = data[0], max = data[0];
1049 double total = 0.0;
1050 int j;
1051 for (j = 0; j < level; ++j)
1052 gclog_or_tty->print(" ");
1053 gclog_or_tty->print("[%s :", str);
1054 for (uint i = 0; i < ParallelGCThreads; ++i) {
1055 double val = data[i];
1056 if (val < min)
1057 min = val;
1058 if (val > max)
1059 max = val;
1060 total += val;
1061 gclog_or_tty->print(" %d", (int) val);
1062 }
1063 if (summary) {
1064 gclog_or_tty->print_cr("");
1065 double avg = total / (double) ParallelGCThreads;
1066 gclog_or_tty->print(" ");
1067 for (j = 0; j < level; ++j)
1068 gclog_or_tty->print(" ");
1069 gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
1070 (int)total, (int)avg, (int)min, (int)max);
1071 }
1072 gclog_or_tty->print_cr("]");
1073 }
1075 void G1CollectorPolicy::print_stats (int level,
1076 const char* str,
1077 double value) {
1078 for (int j = 0; j < level; ++j)
1079 gclog_or_tty->print(" ");
1080 gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
1081 }
1083 void G1CollectorPolicy::print_stats (int level,
1084 const char* str,
1085 int value) {
1086 for (int j = 0; j < level; ++j)
1087 gclog_or_tty->print(" ");
1088 gclog_or_tty->print_cr("[%s: %d]", str, value);
1089 }
1091 double G1CollectorPolicy::avg_value (double* data) {
1092 if (G1CollectedHeap::use_parallel_gc_threads()) {
1093 double ret = 0.0;
1094 for (uint i = 0; i < ParallelGCThreads; ++i)
1095 ret += data[i];
1096 return ret / (double) ParallelGCThreads;
1097 } else {
1098 return data[0];
1099 }
1100 }
1102 double G1CollectorPolicy::max_value (double* data) {
1103 if (G1CollectedHeap::use_parallel_gc_threads()) {
1104 double ret = data[0];
1105 for (uint i = 1; i < ParallelGCThreads; ++i)
1106 if (data[i] > ret)
1107 ret = data[i];
1108 return ret;
1109 } else {
1110 return data[0];
1111 }
1112 }
1114 double G1CollectorPolicy::sum_of_values (double* data) {
1115 if (G1CollectedHeap::use_parallel_gc_threads()) {
1116 double sum = 0.0;
1117 for (uint i = 0; i < ParallelGCThreads; i++)
1118 sum += data[i];
1119 return sum;
1120 } else {
1121 return data[0];
1122 }
1123 }
1125 double G1CollectorPolicy::max_sum (double* data1,
1126 double* data2) {
1127 double ret = data1[0] + data2[0];
1129 if (G1CollectedHeap::use_parallel_gc_threads()) {
1130 for (uint i = 1; i < ParallelGCThreads; ++i) {
1131 double data = data1[i] + data2[i];
1132 if (data > ret)
1133 ret = data;
1134 }
1135 }
1136 return ret;
1137 }
1139 // Anything below that is considered to be zero
1140 #define MIN_TIMER_GRANULARITY 0.0000001
1142 void G1CollectorPolicy::record_collection_pause_end() {
1143 double end_time_sec = os::elapsedTime();
1144 double elapsed_ms = _last_pause_time_ms;
1145 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1146 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1147 size_t rs_size =
1148 _cur_collection_pause_used_regions_at_start - collection_set_size();
1149 size_t cur_used_bytes = _g1->used();
1150 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1151 bool last_pause_included_initial_mark = false;
1152 bool update_stats = !_g1->evacuation_failed();
1154 #ifndef PRODUCT
1155 if (G1YoungSurvRateVerbose) {
1156 gclog_or_tty->print_cr("");
1157 _short_lived_surv_rate_group->print();
1158 // do that for any other surv rate groups too
1159 }
1160 #endif // PRODUCT
1162 if (in_young_gc_mode()) {
1163 last_pause_included_initial_mark = during_initial_mark_pause();
1164 if (last_pause_included_initial_mark)
1165 record_concurrent_mark_init_end_pre(0.0);
1167 size_t min_used_targ =
1168 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1171 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1172 assert(!last_pause_included_initial_mark, "invariant");
1173 if (cur_used_bytes > min_used_targ &&
1174 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1175 assert(!during_initial_mark_pause(), "we should not see this here");
1177 // Note: this might have already been set, if during the last
1178 // pause we decided to start a cycle but at the beginning of
1179 // this pause we decided to postpone it. That's OK.
1180 set_initiate_conc_mark_if_possible();
1181 }
1182 }
1184 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1185 }
1187 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1188 end_time_sec, false);
1190 guarantee(_cur_collection_pause_used_regions_at_start >=
1191 collection_set_size(),
1192 "Negative RS size?");
1194 // This assert is exempted when we're doing parallel collection pauses,
1195 // because the fragmentation caused by the parallel GC allocation buffers
1196 // can lead to more memory being used during collection than was used
1197 // before. Best leave this out until the fragmentation problem is fixed.
1198 // Pauses in which evacuation failed can also lead to negative
1199 // collections, since no space is reclaimed from a region containing an
1200 // object whose evacuation failed.
1201 // Further, we're now always doing parallel collection. But I'm still
1202 // leaving this here as a placeholder for a more precise assertion later.
1203 // (DLD, 10/05.)
1204 assert((true || parallel) // Always using GC LABs now.
1205 || _g1->evacuation_failed()
1206 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1207 "Negative collection");
1209 size_t freed_bytes =
1210 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1211 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1213 double survival_fraction =
1214 (double)surviving_bytes/
1215 (double)_collection_set_bytes_used_before;
1217 _n_pauses++;
1219 if (update_stats) {
1220 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1221 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1222 _recent_evac_times_ms->add(evac_ms);
1223 _recent_pause_times_ms->add(elapsed_ms);
1225 _recent_rs_sizes->add(rs_size);
1227 // We exempt parallel collection from this check because Alloc Buffer
1228 // fragmentation can produce negative collections. Same with evac
1229 // failure.
1230 // Further, we're now always doing parallel collection. But I'm still
1231 // leaving this here as a placeholder for a more precise assertion later.
1232 // (DLD, 10/05.
1233 assert((true || parallel)
1234 || _g1->evacuation_failed()
1235 || surviving_bytes <= _collection_set_bytes_used_before,
1236 "Or else negative collection!");
1237 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1238 _recent_CS_bytes_surviving->add(surviving_bytes);
1240 // this is where we update the allocation rate of the application
1241 double app_time_ms =
1242 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1243 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1244 // This usually happens due to the timer not having the required
1245 // granularity. Some Linuxes are the usual culprits.
1246 // We'll just set it to something (arbitrarily) small.
1247 app_time_ms = 1.0;
1248 }
1249 size_t regions_allocated =
1250 (_region_num_young - _prev_region_num_young) +
1251 (_region_num_tenured - _prev_region_num_tenured);
1252 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1253 _alloc_rate_ms_seq->add(alloc_rate_ms);
1254 _prev_region_num_young = _region_num_young;
1255 _prev_region_num_tenured = _region_num_tenured;
1257 double interval_ms =
1258 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1259 update_recent_gc_times(end_time_sec, elapsed_ms);
1260 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1261 if (recent_avg_pause_time_ratio() < 0.0 ||
1262 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1263 #ifndef PRODUCT
1264 // Dump info to allow post-facto debugging
1265 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1266 gclog_or_tty->print_cr("-------------------------------------------");
1267 gclog_or_tty->print_cr("Recent GC Times (ms):");
1268 _recent_gc_times_ms->dump();
1269 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1270 _recent_prev_end_times_for_all_gcs_sec->dump();
1271 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1272 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1273 // In debug mode, terminate the JVM if the user wants to debug at this point.
1274 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1275 #endif // !PRODUCT
1276 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1277 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1278 if (_recent_avg_pause_time_ratio < 0.0) {
1279 _recent_avg_pause_time_ratio = 0.0;
1280 } else {
1281 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1282 _recent_avg_pause_time_ratio = 1.0;
1283 }
1284 }
1285 }
1287 if (G1PolicyVerbose > 1) {
1288 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1289 }
1291 PauseSummary* summary = _summary;
1293 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1294 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1295 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1296 double update_rs_processed_buffers =
1297 sum_of_values(_par_last_update_rs_processed_buffers);
1298 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1299 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1300 double termination_time = avg_value(_par_last_termination_times_ms);
1302 double parallel_other_time = _cur_collection_par_time_ms -
1303 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1304 scan_rs_time + obj_copy_time + termination_time);
1305 if (update_stats) {
1306 MainBodySummary* body_summary = summary->main_body_summary();
1307 guarantee(body_summary != NULL, "should not be null!");
1309 if (_satb_drain_time_set)
1310 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1311 else
1312 body_summary->record_satb_drain_time_ms(0.0);
1313 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1314 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1315 body_summary->record_update_rs_time_ms(update_rs_time);
1316 body_summary->record_scan_rs_time_ms(scan_rs_time);
1317 body_summary->record_obj_copy_time_ms(obj_copy_time);
1318 if (parallel) {
1319 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1320 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1321 body_summary->record_termination_time_ms(termination_time);
1322 body_summary->record_parallel_other_time_ms(parallel_other_time);
1323 }
1324 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1325 }
1327 if (G1PolicyVerbose > 1) {
1328 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1329 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1330 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1331 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1332 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1333 " |RS|: " SIZE_FORMAT,
1334 elapsed_ms, recent_avg_time_for_pauses_ms(),
1335 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1336 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1337 evac_ms, recent_avg_time_for_evac_ms(),
1338 scan_rs_time,
1339 recent_avg_time_for_pauses_ms() -
1340 recent_avg_time_for_G1_strong_ms(),
1341 rs_size);
1343 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1344 " At end " SIZE_FORMAT "K\n"
1345 " garbage : " SIZE_FORMAT "K"
1346 " of " SIZE_FORMAT "K\n"
1347 " survival : %6.2f%% (%6.2f%% avg)",
1348 _cur_collection_pause_used_at_start_bytes/K,
1349 _g1->used()/K, freed_bytes/K,
1350 _collection_set_bytes_used_before/K,
1351 survival_fraction*100.0,
1352 recent_avg_survival_fraction()*100.0);
1353 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1354 recent_avg_pause_time_ratio() * 100.0);
1355 }
1357 double other_time_ms = elapsed_ms;
1359 if (_satb_drain_time_set) {
1360 other_time_ms -= _cur_satb_drain_time_ms;
1361 }
1363 if (parallel) {
1364 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1365 } else {
1366 other_time_ms -=
1367 update_rs_time +
1368 ext_root_scan_time + mark_stack_scan_time +
1369 scan_rs_time + obj_copy_time;
1370 }
1372 if (PrintGCDetails) {
1373 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1374 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1375 elapsed_ms / 1000.0);
1377 if (_satb_drain_time_set) {
1378 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1379 }
1380 if (_last_satb_drain_processed_buffers >= 0) {
1381 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1382 }
1383 if (parallel) {
1384 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1385 print_par_stats(2, "GC Worker Start Time",
1386 _par_last_gc_worker_start_times_ms, false);
1387 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1388 print_par_sizes(3, "Processed Buffers",
1389 _par_last_update_rs_processed_buffers, true);
1390 print_par_stats(2, "Ext Root Scanning",
1391 _par_last_ext_root_scan_times_ms);
1392 print_par_stats(2, "Mark Stack Scanning",
1393 _par_last_mark_stack_scan_times_ms);
1394 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1395 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1396 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1397 print_par_sizes(3, "Termination Attempts",
1398 _par_last_termination_attempts, true);
1399 print_par_stats(2, "GC Worker End Time",
1400 _par_last_gc_worker_end_times_ms, false);
1401 print_stats(2, "Other", parallel_other_time);
1402 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1403 } else {
1404 print_stats(1, "Update RS", update_rs_time);
1405 print_stats(2, "Processed Buffers",
1406 (int)update_rs_processed_buffers);
1407 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1408 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1409 print_stats(1, "Scan RS", scan_rs_time);
1410 print_stats(1, "Object Copying", obj_copy_time);
1411 }
1412 #ifndef PRODUCT
1413 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1414 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1415 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1416 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1417 if (_num_cc_clears > 0) {
1418 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1419 }
1420 #endif
1421 print_stats(1, "Other", other_time_ms);
1422 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1424 for (int i = 0; i < _aux_num; ++i) {
1425 if (_cur_aux_times_set[i]) {
1426 char buffer[96];
1427 sprintf(buffer, "Aux%d", i);
1428 print_stats(1, buffer, _cur_aux_times_ms[i]);
1429 }
1430 }
1431 }
1432 if (PrintGCDetails)
1433 gclog_or_tty->print(" [");
1434 if (PrintGC || PrintGCDetails)
1435 _g1->print_size_transition(gclog_or_tty,
1436 _cur_collection_pause_used_at_start_bytes,
1437 _g1->used(), _g1->capacity());
1438 if (PrintGCDetails)
1439 gclog_or_tty->print_cr("]");
1441 _all_pause_times_ms->add(elapsed_ms);
1442 if (update_stats) {
1443 summary->record_total_time_ms(elapsed_ms);
1444 summary->record_other_time_ms(other_time_ms);
1445 }
1446 for (int i = 0; i < _aux_num; ++i)
1447 if (_cur_aux_times_set[i])
1448 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1450 // Reset marks-between-pauses counter.
1451 _n_marks_since_last_pause = 0;
1453 // Update the efficiency-since-mark vars.
1454 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1455 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1456 // This usually happens due to the timer not having the required
1457 // granularity. Some Linuxes are the usual culprits.
1458 // We'll just set it to something (arbitrarily) small.
1459 proc_ms = 1.0;
1460 }
1461 double cur_efficiency = (double) freed_bytes / proc_ms;
1463 bool new_in_marking_window = _in_marking_window;
1464 bool new_in_marking_window_im = false;
1465 if (during_initial_mark_pause()) {
1466 new_in_marking_window = true;
1467 new_in_marking_window_im = true;
1468 }
1470 if (in_young_gc_mode()) {
1471 if (_last_full_young_gc) {
1472 set_full_young_gcs(false);
1473 _last_full_young_gc = false;
1474 }
1476 if ( !_last_young_gc_full ) {
1477 if ( _should_revert_to_full_young_gcs ||
1478 _known_garbage_ratio < 0.05 ||
1479 (adaptive_young_list_length() &&
1480 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1481 set_full_young_gcs(true);
1482 }
1483 }
1484 _should_revert_to_full_young_gcs = false;
1486 if (_last_young_gc_full && !_during_marking)
1487 _young_gc_eff_seq->add(cur_efficiency);
1488 }
1490 _short_lived_surv_rate_group->start_adding_regions();
1491 // do that for any other surv rate groupsx
1493 // <NEW PREDICTION>
1495 if (update_stats) {
1496 double pause_time_ms = elapsed_ms;
1498 size_t diff = 0;
1499 if (_max_pending_cards >= _pending_cards)
1500 diff = _max_pending_cards - _pending_cards;
1501 _pending_card_diff_seq->add((double) diff);
1503 double cost_per_card_ms = 0.0;
1504 if (_pending_cards > 0) {
1505 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1506 _cost_per_card_ms_seq->add(cost_per_card_ms);
1507 }
1509 size_t cards_scanned = _g1->cards_scanned();
1511 double cost_per_entry_ms = 0.0;
1512 if (cards_scanned > 10) {
1513 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1514 if (_last_young_gc_full)
1515 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1516 else
1517 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1518 }
1520 if (_max_rs_lengths > 0) {
1521 double cards_per_entry_ratio =
1522 (double) cards_scanned / (double) _max_rs_lengths;
1523 if (_last_young_gc_full)
1524 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1525 else
1526 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1527 }
1529 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1530 if (rs_length_diff >= 0)
1531 _rs_length_diff_seq->add((double) rs_length_diff);
1533 size_t copied_bytes = surviving_bytes;
1534 double cost_per_byte_ms = 0.0;
1535 if (copied_bytes > 0) {
1536 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1537 if (_in_marking_window)
1538 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1539 else
1540 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1541 }
1543 double all_other_time_ms = pause_time_ms -
1544 (update_rs_time + scan_rs_time + obj_copy_time +
1545 _mark_closure_time_ms + termination_time);
1547 double young_other_time_ms = 0.0;
1548 if (_recorded_young_regions > 0) {
1549 young_other_time_ms =
1550 _recorded_young_cset_choice_time_ms +
1551 _recorded_young_free_cset_time_ms;
1552 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1553 (double) _recorded_young_regions);
1554 }
1555 double non_young_other_time_ms = 0.0;
1556 if (_recorded_non_young_regions > 0) {
1557 non_young_other_time_ms =
1558 _recorded_non_young_cset_choice_time_ms +
1559 _recorded_non_young_free_cset_time_ms;
1561 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1562 (double) _recorded_non_young_regions);
1563 }
1565 double constant_other_time_ms = all_other_time_ms -
1566 (young_other_time_ms + non_young_other_time_ms);
1567 _constant_other_time_ms_seq->add(constant_other_time_ms);
1569 double survival_ratio = 0.0;
1570 if (_bytes_in_collection_set_before_gc > 0) {
1571 survival_ratio = (double) bytes_in_to_space_during_gc() /
1572 (double) _bytes_in_collection_set_before_gc;
1573 }
1575 _pending_cards_seq->add((double) _pending_cards);
1576 _scanned_cards_seq->add((double) cards_scanned);
1577 _rs_lengths_seq->add((double) _max_rs_lengths);
1579 double expensive_region_limit_ms =
1580 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1581 if (expensive_region_limit_ms < 0.0) {
1582 // this means that the other time was predicted to be longer than
1583 // than the max pause time
1584 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1585 }
1586 _expensive_region_limit_ms = expensive_region_limit_ms;
1588 if (PREDICTIONS_VERBOSE) {
1589 gclog_or_tty->print_cr("");
1590 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1591 "REGIONS %d %d %d "
1592 "PENDING_CARDS %d %d "
1593 "CARDS_SCANNED %d %d "
1594 "RS_LENGTHS %d %d "
1595 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1596 "SURVIVAL_RATIO %1.6lf %1.6lf "
1597 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1598 "OTHER_YOUNG %1.6lf %1.6lf "
1599 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1600 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1601 "ELAPSED %1.6lf %1.6lf ",
1602 _cur_collection_start_sec,
1603 (!_last_young_gc_full) ? 2 :
1604 (last_pause_included_initial_mark) ? 1 : 0,
1605 _recorded_region_num,
1606 _recorded_young_regions,
1607 _recorded_non_young_regions,
1608 _predicted_pending_cards, _pending_cards,
1609 _predicted_cards_scanned, cards_scanned,
1610 _predicted_rs_lengths, _max_rs_lengths,
1611 _predicted_rs_update_time_ms, update_rs_time,
1612 _predicted_rs_scan_time_ms, scan_rs_time,
1613 _predicted_survival_ratio, survival_ratio,
1614 _predicted_object_copy_time_ms, obj_copy_time,
1615 _predicted_constant_other_time_ms, constant_other_time_ms,
1616 _predicted_young_other_time_ms, young_other_time_ms,
1617 _predicted_non_young_other_time_ms,
1618 non_young_other_time_ms,
1619 _vtime_diff_ms, termination_time,
1620 _predicted_pause_time_ms, elapsed_ms);
1621 }
1623 if (G1PolicyVerbose > 0) {
1624 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1625 _predicted_pause_time_ms,
1626 (_within_target) ? "within" : "outside",
1627 elapsed_ms);
1628 }
1630 }
1632 _in_marking_window = new_in_marking_window;
1633 _in_marking_window_im = new_in_marking_window_im;
1634 _free_regions_at_end_of_collection = _g1->free_regions();
1635 calculate_young_list_min_length();
1636 calculate_young_list_target_length();
1638 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1639 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1640 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1641 // </NEW PREDICTION>
1642 }
1644 // <NEW PREDICTION>
1646 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1647 double update_rs_processed_buffers,
1648 double goal_ms) {
1649 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1650 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1652 if (G1UseAdaptiveConcRefinement) {
1653 const int k_gy = 3, k_gr = 6;
1654 const double inc_k = 1.1, dec_k = 0.9;
1656 int g = cg1r->green_zone();
1657 if (update_rs_time > goal_ms) {
1658 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1659 } else {
1660 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1661 g = (int)MAX2(g * inc_k, g + 1.0);
1662 }
1663 }
1664 // Change the refinement threads params
1665 cg1r->set_green_zone(g);
1666 cg1r->set_yellow_zone(g * k_gy);
1667 cg1r->set_red_zone(g * k_gr);
1668 cg1r->reinitialize_threads();
1670 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1671 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1672 cg1r->yellow_zone());
1673 // Change the barrier params
1674 dcqs.set_process_completed_threshold(processing_threshold);
1675 dcqs.set_max_completed_queue(cg1r->red_zone());
1676 }
1678 int curr_queue_size = dcqs.completed_buffers_num();
1679 if (curr_queue_size >= cg1r->yellow_zone()) {
1680 dcqs.set_completed_queue_padding(curr_queue_size);
1681 } else {
1682 dcqs.set_completed_queue_padding(0);
1683 }
1684 dcqs.notify_if_necessary();
1685 }
1687 double
1688 G1CollectorPolicy::
1689 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1690 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1692 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1693 size_t young_num = g1h->young_list()->length();
1694 if (young_num == 0)
1695 return 0.0;
1697 young_num += adjustment;
1698 size_t pending_cards = predict_pending_cards();
1699 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1700 predict_rs_length_diff();
1701 size_t card_num;
1702 if (full_young_gcs())
1703 card_num = predict_young_card_num(rs_lengths);
1704 else
1705 card_num = predict_non_young_card_num(rs_lengths);
1706 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1707 double accum_yg_surv_rate =
1708 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1710 size_t bytes_to_copy =
1711 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1713 return
1714 predict_rs_update_time_ms(pending_cards) +
1715 predict_rs_scan_time_ms(card_num) +
1716 predict_object_copy_time_ms(bytes_to_copy) +
1717 predict_young_other_time_ms(young_num) +
1718 predict_constant_other_time_ms();
1719 }
1721 double
1722 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1723 size_t rs_length = predict_rs_length_diff();
1724 size_t card_num;
1725 if (full_young_gcs())
1726 card_num = predict_young_card_num(rs_length);
1727 else
1728 card_num = predict_non_young_card_num(rs_length);
1729 return predict_base_elapsed_time_ms(pending_cards, card_num);
1730 }
1732 double
1733 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1734 size_t scanned_cards) {
1735 return
1736 predict_rs_update_time_ms(pending_cards) +
1737 predict_rs_scan_time_ms(scanned_cards) +
1738 predict_constant_other_time_ms();
1739 }
1741 double
1742 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1743 bool young) {
1744 size_t rs_length = hr->rem_set()->occupied();
1745 size_t card_num;
1746 if (full_young_gcs())
1747 card_num = predict_young_card_num(rs_length);
1748 else
1749 card_num = predict_non_young_card_num(rs_length);
1750 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1752 double region_elapsed_time_ms =
1753 predict_rs_scan_time_ms(card_num) +
1754 predict_object_copy_time_ms(bytes_to_copy);
1756 if (young)
1757 region_elapsed_time_ms += predict_young_other_time_ms(1);
1758 else
1759 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1761 return region_elapsed_time_ms;
1762 }
1764 size_t
1765 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1766 size_t bytes_to_copy;
1767 if (hr->is_marked())
1768 bytes_to_copy = hr->max_live_bytes();
1769 else {
1770 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1771 "invariant" );
1772 int age = hr->age_in_surv_rate_group();
1773 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1774 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1775 }
1777 return bytes_to_copy;
1778 }
1780 void
1781 G1CollectorPolicy::start_recording_regions() {
1782 _recorded_rs_lengths = 0;
1783 _recorded_young_regions = 0;
1784 _recorded_non_young_regions = 0;
1786 #if PREDICTIONS_VERBOSE
1787 _recorded_marked_bytes = 0;
1788 _recorded_young_bytes = 0;
1789 _predicted_bytes_to_copy = 0;
1790 _predicted_rs_lengths = 0;
1791 _predicted_cards_scanned = 0;
1792 #endif // PREDICTIONS_VERBOSE
1793 }
1795 void
1796 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1797 #if PREDICTIONS_VERBOSE
1798 if (!young) {
1799 _recorded_marked_bytes += hr->max_live_bytes();
1800 }
1801 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1802 #endif // PREDICTIONS_VERBOSE
1804 size_t rs_length = hr->rem_set()->occupied();
1805 _recorded_rs_lengths += rs_length;
1806 }
1808 void
1809 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1810 assert(!hr->is_young(), "should not call this");
1811 ++_recorded_non_young_regions;
1812 record_cset_region_info(hr, false);
1813 }
1815 void
1816 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1817 _recorded_young_regions = n_regions;
1818 }
1820 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1821 #if PREDICTIONS_VERBOSE
1822 _recorded_young_bytes = bytes;
1823 #endif // PREDICTIONS_VERBOSE
1824 }
1826 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1827 _recorded_rs_lengths = rs_lengths;
1828 }
1830 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1831 _predicted_bytes_to_copy = bytes;
1832 }
1834 void
1835 G1CollectorPolicy::end_recording_regions() {
1836 // The _predicted_pause_time_ms field is referenced in code
1837 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1838 _predicted_pause_time_ms = -1.0;
1840 #if PREDICTIONS_VERBOSE
1841 _predicted_pending_cards = predict_pending_cards();
1842 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1843 if (full_young_gcs())
1844 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1845 else
1846 _predicted_cards_scanned +=
1847 predict_non_young_card_num(_predicted_rs_lengths);
1848 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1850 _predicted_rs_update_time_ms =
1851 predict_rs_update_time_ms(_g1->pending_card_num());
1852 _predicted_rs_scan_time_ms =
1853 predict_rs_scan_time_ms(_predicted_cards_scanned);
1854 _predicted_object_copy_time_ms =
1855 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1856 _predicted_constant_other_time_ms =
1857 predict_constant_other_time_ms();
1858 _predicted_young_other_time_ms =
1859 predict_young_other_time_ms(_recorded_young_regions);
1860 _predicted_non_young_other_time_ms =
1861 predict_non_young_other_time_ms(_recorded_non_young_regions);
1863 _predicted_pause_time_ms =
1864 _predicted_rs_update_time_ms +
1865 _predicted_rs_scan_time_ms +
1866 _predicted_object_copy_time_ms +
1867 _predicted_constant_other_time_ms +
1868 _predicted_young_other_time_ms +
1869 _predicted_non_young_other_time_ms;
1870 #endif // PREDICTIONS_VERBOSE
1871 }
1873 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1874 predicted_time_ms) {
1875 // I don't think we need to do this when in young GC mode since
1876 // marking will be initiated next time we hit the soft limit anyway...
1877 if (predicted_time_ms > _expensive_region_limit_ms) {
1878 if (!in_young_gc_mode()) {
1879 set_full_young_gcs(true);
1880 // We might want to do something different here. However,
1881 // right now we don't support the non-generational G1 mode
1882 // (and in fact we are planning to remove the associated code,
1883 // see CR 6814390). So, let's leave it as is and this will be
1884 // removed some time in the future
1885 ShouldNotReachHere();
1886 set_during_initial_mark_pause();
1887 } else
1888 // no point in doing another partial one
1889 _should_revert_to_full_young_gcs = true;
1890 }
1891 }
1893 // </NEW PREDICTION>
1896 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1897 double elapsed_ms) {
1898 _recent_gc_times_ms->add(elapsed_ms);
1899 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1900 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1901 }
1903 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1904 if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
1905 else return _recent_pause_times_ms->avg();
1906 }
1908 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
1909 if (_recent_CH_strong_roots_times_ms->num() == 0)
1910 return (double)MaxGCPauseMillis/3.0;
1911 else return _recent_CH_strong_roots_times_ms->avg();
1912 }
1914 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
1915 if (_recent_G1_strong_roots_times_ms->num() == 0)
1916 return (double)MaxGCPauseMillis/3.0;
1917 else return _recent_G1_strong_roots_times_ms->avg();
1918 }
1920 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
1921 if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
1922 else return _recent_evac_times_ms->avg();
1923 }
1925 int G1CollectorPolicy::number_of_recent_gcs() {
1926 assert(_recent_CH_strong_roots_times_ms->num() ==
1927 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
1928 assert(_recent_G1_strong_roots_times_ms->num() ==
1929 _recent_evac_times_ms->num(), "Sequence out of sync");
1930 assert(_recent_evac_times_ms->num() ==
1931 _recent_pause_times_ms->num(), "Sequence out of sync");
1932 assert(_recent_pause_times_ms->num() ==
1933 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1934 assert(_recent_CS_bytes_used_before->num() ==
1935 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1936 return _recent_pause_times_ms->num();
1937 }
1939 double G1CollectorPolicy::recent_avg_survival_fraction() {
1940 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1941 _recent_CS_bytes_used_before);
1942 }
1944 double G1CollectorPolicy::last_survival_fraction() {
1945 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1946 _recent_CS_bytes_used_before);
1947 }
1949 double
1950 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1951 TruncatedSeq* before) {
1952 assert(surviving->num() == before->num(), "Sequence out of sync");
1953 if (before->sum() > 0.0) {
1954 double recent_survival_rate = surviving->sum() / before->sum();
1955 // We exempt parallel collection from this check because Alloc Buffer
1956 // fragmentation can produce negative collections.
1957 // Further, we're now always doing parallel collection. But I'm still
1958 // leaving this here as a placeholder for a more precise assertion later.
1959 // (DLD, 10/05.)
1960 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1961 _g1->evacuation_failed() ||
1962 recent_survival_rate <= 1.0, "Or bad frac");
1963 return recent_survival_rate;
1964 } else {
1965 return 1.0; // Be conservative.
1966 }
1967 }
1969 double
1970 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
1971 TruncatedSeq* before) {
1972 assert(surviving->num() == before->num(), "Sequence out of sync");
1973 if (surviving->num() > 0 && before->last() > 0.0) {
1974 double last_survival_rate = surviving->last() / before->last();
1975 // We exempt parallel collection from this check because Alloc Buffer
1976 // fragmentation can produce negative collections.
1977 // Further, we're now always doing parallel collection. But I'm still
1978 // leaving this here as a placeholder for a more precise assertion later.
1979 // (DLD, 10/05.)
1980 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1981 last_survival_rate <= 1.0, "Or bad frac");
1982 return last_survival_rate;
1983 } else {
1984 return 1.0;
1985 }
1986 }
1988 static const int survival_min_obs = 5;
1989 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
1990 static const double min_survival_rate = 0.1;
1992 double
1993 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
1994 double latest) {
1995 double res = avg;
1996 if (number_of_recent_gcs() < survival_min_obs) {
1997 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
1998 }
1999 res = MAX2(res, latest);
2000 res = MAX2(res, min_survival_rate);
2001 // In the parallel case, LAB fragmentation can produce "negative
2002 // collections"; so can evac failure. Cap at 1.0
2003 res = MIN2(res, 1.0);
2004 return res;
2005 }
2007 size_t G1CollectorPolicy::expansion_amount() {
2008 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
2009 // We will double the existing space, or take
2010 // G1ExpandByPercentOfAvailable % of the available expansion
2011 // space, whichever is smaller, bounded below by a minimum
2012 // expansion (unless that's all that's left.)
2013 const size_t min_expand_bytes = 1*M;
2014 size_t reserved_bytes = _g1->max_capacity();
2015 size_t committed_bytes = _g1->capacity();
2016 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2017 size_t expand_bytes;
2018 size_t expand_bytes_via_pct =
2019 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2020 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2021 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2022 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2023 if (G1PolicyVerbose > 1) {
2024 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2025 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2026 " Answer = %d.\n",
2027 recent_avg_pause_time_ratio(),
2028 byte_size_in_proper_unit(committed_bytes),
2029 proper_unit_for_byte_size(committed_bytes),
2030 byte_size_in_proper_unit(uncommitted_bytes),
2031 proper_unit_for_byte_size(uncommitted_bytes),
2032 byte_size_in_proper_unit(expand_bytes_via_pct),
2033 proper_unit_for_byte_size(expand_bytes_via_pct),
2034 byte_size_in_proper_unit(expand_bytes),
2035 proper_unit_for_byte_size(expand_bytes));
2036 }
2037 return expand_bytes;
2038 } else {
2039 return 0;
2040 }
2041 }
2043 void G1CollectorPolicy::note_start_of_mark_thread() {
2044 _mark_thread_startup_sec = os::elapsedTime();
2045 }
2047 class CountCSClosure: public HeapRegionClosure {
2048 G1CollectorPolicy* _g1_policy;
2049 public:
2050 CountCSClosure(G1CollectorPolicy* g1_policy) :
2051 _g1_policy(g1_policy) {}
2052 bool doHeapRegion(HeapRegion* r) {
2053 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2054 return false;
2055 }
2056 };
2058 void G1CollectorPolicy::count_CS_bytes_used() {
2059 CountCSClosure cs_closure(this);
2060 _g1->collection_set_iterate(&cs_closure);
2061 }
2063 static void print_indent(int level) {
2064 for (int j = 0; j < level+1; ++j)
2065 gclog_or_tty->print(" ");
2066 }
2068 void G1CollectorPolicy::print_summary (int level,
2069 const char* str,
2070 NumberSeq* seq) const {
2071 double sum = seq->sum();
2072 print_indent(level);
2073 gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2074 str, sum / 1000.0, seq->avg());
2075 }
2077 void G1CollectorPolicy::print_summary_sd (int level,
2078 const char* str,
2079 NumberSeq* seq) const {
2080 print_summary(level, str, seq);
2081 print_indent(level + 5);
2082 gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2083 seq->num(), seq->sd(), seq->maximum());
2084 }
2086 void G1CollectorPolicy::check_other_times(int level,
2087 NumberSeq* other_times_ms,
2088 NumberSeq* calc_other_times_ms) const {
2089 bool should_print = false;
2091 double max_sum = MAX2(fabs(other_times_ms->sum()),
2092 fabs(calc_other_times_ms->sum()));
2093 double min_sum = MIN2(fabs(other_times_ms->sum()),
2094 fabs(calc_other_times_ms->sum()));
2095 double sum_ratio = max_sum / min_sum;
2096 if (sum_ratio > 1.1) {
2097 should_print = true;
2098 print_indent(level + 1);
2099 gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2100 }
2102 double max_avg = MAX2(fabs(other_times_ms->avg()),
2103 fabs(calc_other_times_ms->avg()));
2104 double min_avg = MIN2(fabs(other_times_ms->avg()),
2105 fabs(calc_other_times_ms->avg()));
2106 double avg_ratio = max_avg / min_avg;
2107 if (avg_ratio > 1.1) {
2108 should_print = true;
2109 print_indent(level + 1);
2110 gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2111 }
2113 if (other_times_ms->sum() < -0.01) {
2114 print_indent(level + 1);
2115 gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2116 }
2118 if (other_times_ms->avg() < -0.01) {
2119 print_indent(level + 1);
2120 gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2121 }
2123 if (calc_other_times_ms->sum() < -0.01) {
2124 should_print = true;
2125 print_indent(level + 1);
2126 gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2127 }
2129 if (calc_other_times_ms->avg() < -0.01) {
2130 should_print = true;
2131 print_indent(level + 1);
2132 gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2133 }
2135 if (should_print)
2136 print_summary(level, "Other(Calc)", calc_other_times_ms);
2137 }
2139 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2140 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
2141 MainBodySummary* body_summary = summary->main_body_summary();
2142 if (summary->get_total_seq()->num() > 0) {
2143 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2144 if (body_summary != NULL) {
2145 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2146 if (parallel) {
2147 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2148 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2149 print_summary(2, "Ext Root Scanning",
2150 body_summary->get_ext_root_scan_seq());
2151 print_summary(2, "Mark Stack Scanning",
2152 body_summary->get_mark_stack_scan_seq());
2153 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2154 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2155 print_summary(2, "Termination", body_summary->get_termination_seq());
2156 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2157 {
2158 NumberSeq* other_parts[] = {
2159 body_summary->get_update_rs_seq(),
2160 body_summary->get_ext_root_scan_seq(),
2161 body_summary->get_mark_stack_scan_seq(),
2162 body_summary->get_scan_rs_seq(),
2163 body_summary->get_obj_copy_seq(),
2164 body_summary->get_termination_seq()
2165 };
2166 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2167 6, other_parts);
2168 check_other_times(2, body_summary->get_parallel_other_seq(),
2169 &calc_other_times_ms);
2170 }
2171 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2172 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2173 } else {
2174 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2175 print_summary(1, "Ext Root Scanning",
2176 body_summary->get_ext_root_scan_seq());
2177 print_summary(1, "Mark Stack Scanning",
2178 body_summary->get_mark_stack_scan_seq());
2179 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2180 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2181 }
2182 }
2183 print_summary(1, "Other", summary->get_other_seq());
2184 {
2185 if (body_summary != NULL) {
2186 NumberSeq calc_other_times_ms;
2187 if (parallel) {
2188 // parallel
2189 NumberSeq* other_parts[] = {
2190 body_summary->get_satb_drain_seq(),
2191 body_summary->get_parallel_seq(),
2192 body_summary->get_clear_ct_seq()
2193 };
2194 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2195 3, other_parts);
2196 } else {
2197 // serial
2198 NumberSeq* other_parts[] = {
2199 body_summary->get_satb_drain_seq(),
2200 body_summary->get_update_rs_seq(),
2201 body_summary->get_ext_root_scan_seq(),
2202 body_summary->get_mark_stack_scan_seq(),
2203 body_summary->get_scan_rs_seq(),
2204 body_summary->get_obj_copy_seq()
2205 };
2206 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2207 6, other_parts);
2208 }
2209 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2210 }
2211 }
2212 } else {
2213 print_indent(0);
2214 gclog_or_tty->print_cr("none");
2215 }
2216 gclog_or_tty->print_cr("");
2217 }
2219 void G1CollectorPolicy::print_tracing_info() const {
2220 if (TraceGen0Time) {
2221 gclog_or_tty->print_cr("ALL PAUSES");
2222 print_summary_sd(0, "Total", _all_pause_times_ms);
2223 gclog_or_tty->print_cr("");
2224 gclog_or_tty->print_cr("");
2225 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2226 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2227 gclog_or_tty->print_cr("");
2229 gclog_or_tty->print_cr("EVACUATION PAUSES");
2230 print_summary(_summary);
2232 gclog_or_tty->print_cr("MISC");
2233 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2234 print_summary_sd(0, "Yields", _all_yield_times_ms);
2235 for (int i = 0; i < _aux_num; ++i) {
2236 if (_all_aux_times_ms[i].num() > 0) {
2237 char buffer[96];
2238 sprintf(buffer, "Aux%d", i);
2239 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2240 }
2241 }
2243 size_t all_region_num = _region_num_young + _region_num_tenured;
2244 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2245 "Tenured %8d (%6.2lf%%)",
2246 all_region_num,
2247 _region_num_young,
2248 (double) _region_num_young / (double) all_region_num * 100.0,
2249 _region_num_tenured,
2250 (double) _region_num_tenured / (double) all_region_num * 100.0);
2251 }
2252 if (TraceGen1Time) {
2253 if (_all_full_gc_times_ms->num() > 0) {
2254 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2255 _all_full_gc_times_ms->num(),
2256 _all_full_gc_times_ms->sum() / 1000.0);
2257 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2258 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2259 _all_full_gc_times_ms->sd(),
2260 _all_full_gc_times_ms->maximum());
2261 }
2262 }
2263 }
2265 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2266 #ifndef PRODUCT
2267 _short_lived_surv_rate_group->print_surv_rate_summary();
2268 // add this call for any other surv rate groups
2269 #endif // PRODUCT
2270 }
2272 void
2273 G1CollectorPolicy::update_region_num(bool young) {
2274 if (young) {
2275 ++_region_num_young;
2276 } else {
2277 ++_region_num_tenured;
2278 }
2279 }
2281 #ifndef PRODUCT
2282 // for debugging, bit of a hack...
2283 static char*
2284 region_num_to_mbs(int length) {
2285 static char buffer[64];
2286 double bytes = (double) (length * HeapRegion::GrainBytes);
2287 double mbs = bytes / (double) (1024 * 1024);
2288 sprintf(buffer, "%7.2lfMB", mbs);
2289 return buffer;
2290 }
2291 #endif // PRODUCT
2293 size_t G1CollectorPolicy::max_regions(int purpose) {
2294 switch (purpose) {
2295 case GCAllocForSurvived:
2296 return _max_survivor_regions;
2297 case GCAllocForTenured:
2298 return REGIONS_UNLIMITED;
2299 default:
2300 ShouldNotReachHere();
2301 return REGIONS_UNLIMITED;
2302 };
2303 }
2305 void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
2306 size_t expansion_region_num = 0;
2307 if (GCLockerEdenExpansionPercent > 0) {
2308 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2309 double expansion_region_num_d = perc * (double) _young_list_target_length;
2310 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2311 // less than 1.0) we'll get 1.
2312 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2313 } else {
2314 assert(expansion_region_num == 0, "sanity");
2315 }
2316 _young_list_max_length = _young_list_target_length + expansion_region_num;
2317 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2318 }
2320 // Calculates survivor space parameters.
2321 void G1CollectorPolicy::calculate_survivors_policy()
2322 {
2323 if (G1FixedSurvivorSpaceSize == 0) {
2324 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2325 } else {
2326 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2327 }
2329 if (G1FixedTenuringThreshold) {
2330 _tenuring_threshold = MaxTenuringThreshold;
2331 } else {
2332 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2333 HeapRegion::GrainWords * _max_survivor_regions);
2334 }
2335 }
2337 #ifndef PRODUCT
2338 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2339 CollectionSetChooser* _chooser;
2340 public:
2341 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2342 _chooser(chooser) {}
2344 bool doHeapRegion(HeapRegion* r) {
2345 if (!r->continuesHumongous()) {
2346 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2347 }
2348 return false;
2349 }
2350 };
2352 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2353 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2354 _g1->heap_region_iterate(&cl);
2355 return true;
2356 }
2357 #endif
2359 bool
2360 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2361 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2362 if (!during_cycle) {
2363 set_initiate_conc_mark_if_possible();
2364 return true;
2365 } else {
2366 return false;
2367 }
2368 }
2370 void
2371 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2372 // We are about to decide on whether this pause will be an
2373 // initial-mark pause.
2375 // First, during_initial_mark_pause() should not be already set. We
2376 // will set it here if we have to. However, it should be cleared by
2377 // the end of the pause (it's only set for the duration of an
2378 // initial-mark pause).
2379 assert(!during_initial_mark_pause(), "pre-condition");
2381 if (initiate_conc_mark_if_possible()) {
2382 // We had noticed on a previous pause that the heap occupancy has
2383 // gone over the initiating threshold and we should start a
2384 // concurrent marking cycle. So we might initiate one.
2386 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2387 if (!during_cycle) {
2388 // The concurrent marking thread is not "during a cycle", i.e.,
2389 // it has completed the last one. So we can go ahead and
2390 // initiate a new cycle.
2392 set_during_initial_mark_pause();
2394 // And we can now clear initiate_conc_mark_if_possible() as
2395 // we've already acted on it.
2396 clear_initiate_conc_mark_if_possible();
2397 } else {
2398 // The concurrent marking thread is still finishing up the
2399 // previous cycle. If we start one right now the two cycles
2400 // overlap. In particular, the concurrent marking thread might
2401 // be in the process of clearing the next marking bitmap (which
2402 // we will use for the next cycle if we start one). Starting a
2403 // cycle now will be bad given that parts of the marking
2404 // information might get cleared by the marking thread. And we
2405 // cannot wait for the marking thread to finish the cycle as it
2406 // periodically yields while clearing the next marking bitmap
2407 // and, if it's in a yield point, it's waiting for us to
2408 // finish. So, at this point we will not start a cycle and we'll
2409 // let the concurrent marking thread complete the last one.
2410 }
2411 }
2412 }
2414 void
2415 G1CollectorPolicy_BestRegionsFirst::
2416 record_collection_pause_start(double start_time_sec, size_t start_used) {
2417 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2418 }
2420 class NextNonCSElemFinder: public HeapRegionClosure {
2421 HeapRegion* _res;
2422 public:
2423 NextNonCSElemFinder(): _res(NULL) {}
2424 bool doHeapRegion(HeapRegion* r) {
2425 if (!r->in_collection_set()) {
2426 _res = r;
2427 return true;
2428 } else {
2429 return false;
2430 }
2431 }
2432 HeapRegion* res() { return _res; }
2433 };
2435 class KnownGarbageClosure: public HeapRegionClosure {
2436 CollectionSetChooser* _hrSorted;
2438 public:
2439 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2440 _hrSorted(hrSorted)
2441 {}
2443 bool doHeapRegion(HeapRegion* r) {
2444 // We only include humongous regions in collection
2445 // sets when concurrent mark shows that their contained object is
2446 // unreachable.
2448 // Do we have any marking information for this region?
2449 if (r->is_marked()) {
2450 // We don't include humongous regions in collection
2451 // sets because we collect them immediately at the end of a marking
2452 // cycle. We also don't include young regions because we *must*
2453 // include them in the next collection pause.
2454 if (!r->isHumongous() && !r->is_young()) {
2455 _hrSorted->addMarkedHeapRegion(r);
2456 }
2457 }
2458 return false;
2459 }
2460 };
2462 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2463 CollectionSetChooser* _hrSorted;
2464 jint _marked_regions_added;
2465 jint _chunk_size;
2466 jint _cur_chunk_idx;
2467 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2468 int _worker;
2469 int _invokes;
2471 void get_new_chunk() {
2472 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2473 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2474 }
2475 void add_region(HeapRegion* r) {
2476 if (_cur_chunk_idx == _cur_chunk_end) {
2477 get_new_chunk();
2478 }
2479 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2480 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2481 _marked_regions_added++;
2482 _cur_chunk_idx++;
2483 }
2485 public:
2486 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2487 jint chunk_size,
2488 int worker) :
2489 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2490 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2491 _invokes(0)
2492 {}
2494 bool doHeapRegion(HeapRegion* r) {
2495 // We only include humongous regions in collection
2496 // sets when concurrent mark shows that their contained object is
2497 // unreachable.
2498 _invokes++;
2500 // Do we have any marking information for this region?
2501 if (r->is_marked()) {
2502 // We don't include humongous regions in collection
2503 // sets because we collect them immediately at the end of a marking
2504 // cycle.
2505 // We also do not include young regions in collection sets
2506 if (!r->isHumongous() && !r->is_young()) {
2507 add_region(r);
2508 }
2509 }
2510 return false;
2511 }
2512 jint marked_regions_added() { return _marked_regions_added; }
2513 int invokes() { return _invokes; }
2514 };
2516 class ParKnownGarbageTask: public AbstractGangTask {
2517 CollectionSetChooser* _hrSorted;
2518 jint _chunk_size;
2519 G1CollectedHeap* _g1;
2520 public:
2521 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2522 AbstractGangTask("ParKnownGarbageTask"),
2523 _hrSorted(hrSorted), _chunk_size(chunk_size),
2524 _g1(G1CollectedHeap::heap())
2525 {}
2527 void work(int i) {
2528 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2529 // Back to zero for the claim value.
2530 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2531 HeapRegion::InitialClaimValue);
2532 jint regions_added = parKnownGarbageCl.marked_regions_added();
2533 _hrSorted->incNumMarkedHeapRegions(regions_added);
2534 if (G1PrintParCleanupStats) {
2535 gclog_or_tty->print(" Thread %d called %d times, added %d regions to list.\n",
2536 i, parKnownGarbageCl.invokes(), regions_added);
2537 }
2538 }
2539 };
2541 void
2542 G1CollectorPolicy_BestRegionsFirst::
2543 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2544 size_t max_live_bytes) {
2545 double start;
2546 if (G1PrintParCleanupStats) start = os::elapsedTime();
2547 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2549 _collectionSetChooser->clearMarkedHeapRegions();
2550 double clear_marked_end;
2551 if (G1PrintParCleanupStats) {
2552 clear_marked_end = os::elapsedTime();
2553 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2554 (clear_marked_end - start)*1000.0);
2555 }
2556 if (G1CollectedHeap::use_parallel_gc_threads()) {
2557 const size_t OverpartitionFactor = 4;
2558 const size_t MinWorkUnit = 8;
2559 const size_t WorkUnit =
2560 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2561 MinWorkUnit);
2562 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2563 WorkUnit);
2564 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2565 (int) WorkUnit);
2566 _g1->workers()->run_task(&parKnownGarbageTask);
2568 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2569 "sanity check");
2570 } else {
2571 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2572 _g1->heap_region_iterate(&knownGarbagecl);
2573 }
2574 double known_garbage_end;
2575 if (G1PrintParCleanupStats) {
2576 known_garbage_end = os::elapsedTime();
2577 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2578 (known_garbage_end - clear_marked_end)*1000.0);
2579 }
2580 _collectionSetChooser->sortMarkedHeapRegions();
2581 double sort_end;
2582 if (G1PrintParCleanupStats) {
2583 sort_end = os::elapsedTime();
2584 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2585 (sort_end - known_garbage_end)*1000.0);
2586 }
2588 record_concurrent_mark_cleanup_end_work2();
2589 double work2_end;
2590 if (G1PrintParCleanupStats) {
2591 work2_end = os::elapsedTime();
2592 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2593 (work2_end - sort_end)*1000.0);
2594 }
2595 }
2597 // Add the heap region at the head of the non-incremental collection set
2598 void G1CollectorPolicy::
2599 add_to_collection_set(HeapRegion* hr) {
2600 assert(_inc_cset_build_state == Active, "Precondition");
2601 assert(!hr->is_young(), "non-incremental add of young region");
2603 if (G1PrintHeapRegions) {
2604 gclog_or_tty->print_cr("added region to cset "
2605 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2606 "top "PTR_FORMAT", %s",
2607 hr->hrs_index(), hr->bottom(), hr->end(),
2608 hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
2609 }
2611 if (_g1->mark_in_progress())
2612 _g1->concurrent_mark()->registerCSetRegion(hr);
2614 assert(!hr->in_collection_set(), "should not already be in the CSet");
2615 hr->set_in_collection_set(true);
2616 hr->set_next_in_collection_set(_collection_set);
2617 _collection_set = hr;
2618 _collection_set_size++;
2619 _collection_set_bytes_used_before += hr->used();
2620 _g1->register_region_with_in_cset_fast_test(hr);
2621 }
2623 // Initialize the per-collection-set information
2624 void G1CollectorPolicy::start_incremental_cset_building() {
2625 assert(_inc_cset_build_state == Inactive, "Precondition");
2627 _inc_cset_head = NULL;
2628 _inc_cset_tail = NULL;
2629 _inc_cset_size = 0;
2630 _inc_cset_bytes_used_before = 0;
2632 if (in_young_gc_mode()) {
2633 _inc_cset_young_index = 0;
2634 }
2636 _inc_cset_max_finger = 0;
2637 _inc_cset_recorded_young_bytes = 0;
2638 _inc_cset_recorded_rs_lengths = 0;
2639 _inc_cset_predicted_elapsed_time_ms = 0;
2640 _inc_cset_predicted_bytes_to_copy = 0;
2641 _inc_cset_build_state = Active;
2642 }
2644 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2645 // This routine is used when:
2646 // * adding survivor regions to the incremental cset at the end of an
2647 // evacuation pause,
2648 // * adding the current allocation region to the incremental cset
2649 // when it is retired, and
2650 // * updating existing policy information for a region in the
2651 // incremental cset via young list RSet sampling.
2652 // Therefore this routine may be called at a safepoint by the
2653 // VM thread, or in-between safepoints by mutator threads (when
2654 // retiring the current allocation region) or a concurrent
2655 // refine thread (RSet sampling).
2657 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2658 size_t used_bytes = hr->used();
2660 _inc_cset_recorded_rs_lengths += rs_length;
2661 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2663 _inc_cset_bytes_used_before += used_bytes;
2665 // Cache the values we have added to the aggregated informtion
2666 // in the heap region in case we have to remove this region from
2667 // the incremental collection set, or it is updated by the
2668 // rset sampling code
2669 hr->set_recorded_rs_length(rs_length);
2670 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2672 #if PREDICTIONS_VERBOSE
2673 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2674 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2676 // Record the number of bytes used in this region
2677 _inc_cset_recorded_young_bytes += used_bytes;
2679 // Cache the values we have added to the aggregated informtion
2680 // in the heap region in case we have to remove this region from
2681 // the incremental collection set, or it is updated by the
2682 // rset sampling code
2683 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2684 #endif // PREDICTIONS_VERBOSE
2685 }
2687 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2688 // This routine is currently only called as part of the updating of
2689 // existing policy information for regions in the incremental cset that
2690 // is performed by the concurrent refine thread(s) as part of young list
2691 // RSet sampling. Therefore we should not be at a safepoint.
2693 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2694 assert(hr->is_young(), "it should be");
2696 size_t used_bytes = hr->used();
2697 size_t old_rs_length = hr->recorded_rs_length();
2698 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2700 // Subtract the old recorded/predicted policy information for
2701 // the given heap region from the collection set info.
2702 _inc_cset_recorded_rs_lengths -= old_rs_length;
2703 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2705 _inc_cset_bytes_used_before -= used_bytes;
2707 // Clear the values cached in the heap region
2708 hr->set_recorded_rs_length(0);
2709 hr->set_predicted_elapsed_time_ms(0);
2711 #if PREDICTIONS_VERBOSE
2712 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2713 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2715 // Subtract the number of bytes used in this region
2716 _inc_cset_recorded_young_bytes -= used_bytes;
2718 // Clear the values cached in the heap region
2719 hr->set_predicted_bytes_to_copy(0);
2720 #endif // PREDICTIONS_VERBOSE
2721 }
2723 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2724 // Update the collection set information that is dependent on the new RS length
2725 assert(hr->is_young(), "Precondition");
2727 remove_from_incremental_cset_info(hr);
2728 add_to_incremental_cset_info(hr, new_rs_length);
2729 }
2731 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2732 assert( hr->is_young(), "invariant");
2733 assert( hr->young_index_in_cset() == -1, "invariant" );
2734 assert(_inc_cset_build_state == Active, "Precondition");
2736 // We need to clear and set the cached recorded/cached collection set
2737 // information in the heap region here (before the region gets added
2738 // to the collection set). An individual heap region's cached values
2739 // are calculated, aggregated with the policy collection set info,
2740 // and cached in the heap region here (initially) and (subsequently)
2741 // by the Young List sampling code.
2743 size_t rs_length = hr->rem_set()->occupied();
2744 add_to_incremental_cset_info(hr, rs_length);
2746 HeapWord* hr_end = hr->end();
2747 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2749 assert(!hr->in_collection_set(), "invariant");
2750 hr->set_in_collection_set(true);
2751 assert( hr->next_in_collection_set() == NULL, "invariant");
2753 _inc_cset_size++;
2754 _g1->register_region_with_in_cset_fast_test(hr);
2756 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2757 ++_inc_cset_young_index;
2758 }
2760 // Add the region at the RHS of the incremental cset
2761 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2762 // We should only ever be appending survivors at the end of a pause
2763 assert( hr->is_survivor(), "Logic");
2765 // Do the 'common' stuff
2766 add_region_to_incremental_cset_common(hr);
2768 // Now add the region at the right hand side
2769 if (_inc_cset_tail == NULL) {
2770 assert(_inc_cset_head == NULL, "invariant");
2771 _inc_cset_head = hr;
2772 } else {
2773 _inc_cset_tail->set_next_in_collection_set(hr);
2774 }
2775 _inc_cset_tail = hr;
2777 if (G1PrintHeapRegions) {
2778 gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
2779 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2780 "top "PTR_FORMAT", young %s",
2781 hr->hrs_index(), hr->bottom(), hr->end(),
2782 hr->top(), (hr->is_young()) ? "YES" : "NO");
2783 }
2784 }
2786 // Add the region to the LHS of the incremental cset
2787 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2788 // Survivors should be added to the RHS at the end of a pause
2789 assert(!hr->is_survivor(), "Logic");
2791 // Do the 'common' stuff
2792 add_region_to_incremental_cset_common(hr);
2794 // Add the region at the left hand side
2795 hr->set_next_in_collection_set(_inc_cset_head);
2796 if (_inc_cset_head == NULL) {
2797 assert(_inc_cset_tail == NULL, "Invariant");
2798 _inc_cset_tail = hr;
2799 }
2800 _inc_cset_head = hr;
2802 if (G1PrintHeapRegions) {
2803 gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
2804 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2805 "top "PTR_FORMAT", young %s",
2806 hr->hrs_index(), hr->bottom(), hr->end(),
2807 hr->top(), (hr->is_young()) ? "YES" : "NO");
2808 }
2809 }
2811 #ifndef PRODUCT
2812 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2813 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2815 st->print_cr("\nCollection_set:");
2816 HeapRegion* csr = list_head;
2817 while (csr != NULL) {
2818 HeapRegion* next = csr->next_in_collection_set();
2819 assert(csr->in_collection_set(), "bad CS");
2820 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2821 "age: %4d, y: %d, surv: %d",
2822 csr->bottom(), csr->end(),
2823 csr->top(),
2824 csr->prev_top_at_mark_start(),
2825 csr->next_top_at_mark_start(),
2826 csr->top_at_conc_mark_count(),
2827 csr->age_in_surv_rate_group_cond(),
2828 csr->is_young(),
2829 csr->is_survivor());
2830 csr = next;
2831 }
2832 }
2833 #endif // !PRODUCT
2835 void
2836 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2837 double target_pause_time_ms) {
2838 // Set this here - in case we're not doing young collections.
2839 double non_young_start_time_sec = os::elapsedTime();
2841 start_recording_regions();
2843 guarantee(target_pause_time_ms > 0.0,
2844 err_msg("target_pause_time_ms = %1.6lf should be positive",
2845 target_pause_time_ms));
2846 guarantee(_collection_set == NULL, "Precondition");
2848 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2849 double predicted_pause_time_ms = base_time_ms;
2851 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2853 // the 10% and 50% values are arbitrary...
2854 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2855 time_remaining_ms = 0.50 * target_pause_time_ms;
2856 _within_target = false;
2857 } else {
2858 _within_target = true;
2859 }
2861 // We figure out the number of bytes available for future to-space.
2862 // For new regions without marking information, we must assume the
2863 // worst-case of complete survival. If we have marking information for a
2864 // region, we can bound the amount of live data. We can add a number of
2865 // such regions, as long as the sum of the live data bounds does not
2866 // exceed the available evacuation space.
2867 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2869 size_t expansion_bytes =
2870 _g1->expansion_regions() * HeapRegion::GrainBytes;
2872 _collection_set_bytes_used_before = 0;
2873 _collection_set_size = 0;
2875 // Adjust for expansion and slop.
2876 max_live_bytes = max_live_bytes + expansion_bytes;
2878 HeapRegion* hr;
2879 if (in_young_gc_mode()) {
2880 double young_start_time_sec = os::elapsedTime();
2882 if (G1PolicyVerbose > 0) {
2883 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2884 _g1->young_list()->length());
2885 }
2887 _young_cset_length = 0;
2888 _last_young_gc_full = full_young_gcs() ? true : false;
2890 if (_last_young_gc_full)
2891 ++_full_young_pause_num;
2892 else
2893 ++_partial_young_pause_num;
2895 // The young list is laid with the survivor regions from the previous
2896 // pause are appended to the RHS of the young list, i.e.
2897 // [Newly Young Regions ++ Survivors from last pause].
2899 hr = _g1->young_list()->first_survivor_region();
2900 while (hr != NULL) {
2901 assert(hr->is_survivor(), "badly formed young list");
2902 hr->set_young();
2903 hr = hr->get_next_young_region();
2904 }
2906 // Clear the fields that point to the survivor list - they are
2907 // all young now.
2908 _g1->young_list()->clear_survivors();
2910 if (_g1->mark_in_progress())
2911 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2913 _young_cset_length = _inc_cset_young_index;
2914 _collection_set = _inc_cset_head;
2915 _collection_set_size = _inc_cset_size;
2916 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2918 // For young regions in the collection set, we assume the worst
2919 // case of complete survival
2920 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2922 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2923 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2925 // The number of recorded young regions is the incremental
2926 // collection set's current size
2927 set_recorded_young_regions(_inc_cset_size);
2928 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2929 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2930 #if PREDICTIONS_VERBOSE
2931 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2932 #endif // PREDICTIONS_VERBOSE
2934 if (G1PolicyVerbose > 0) {
2935 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2936 _inc_cset_size);
2937 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2938 max_live_bytes/K);
2939 }
2941 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2943 double young_end_time_sec = os::elapsedTime();
2944 _recorded_young_cset_choice_time_ms =
2945 (young_end_time_sec - young_start_time_sec) * 1000.0;
2947 // We are doing young collections so reset this.
2948 non_young_start_time_sec = young_end_time_sec;
2950 // Note we can use either _collection_set_size or
2951 // _young_cset_length here
2952 if (_collection_set_size > 0 && _last_young_gc_full) {
2953 // don't bother adding more regions...
2954 goto choose_collection_set_end;
2955 }
2956 }
2958 if (!in_young_gc_mode() || !full_young_gcs()) {
2959 bool should_continue = true;
2960 NumberSeq seq;
2961 double avg_prediction = 100000000000000000.0; // something very large
2963 do {
2964 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2965 avg_prediction);
2966 if (hr != NULL) {
2967 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2968 time_remaining_ms -= predicted_time_ms;
2969 predicted_pause_time_ms += predicted_time_ms;
2970 add_to_collection_set(hr);
2971 record_non_young_cset_region(hr);
2972 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2973 if (G1PolicyVerbose > 0) {
2974 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2975 max_live_bytes/K);
2976 }
2977 seq.add(predicted_time_ms);
2978 avg_prediction = seq.avg() + seq.sd();
2979 }
2980 should_continue =
2981 ( hr != NULL) &&
2982 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
2983 : _collection_set_size < _young_list_fixed_length );
2984 } while (should_continue);
2986 if (!adaptive_young_list_length() &&
2987 _collection_set_size < _young_list_fixed_length)
2988 _should_revert_to_full_young_gcs = true;
2989 }
2991 choose_collection_set_end:
2992 stop_incremental_cset_building();
2994 count_CS_bytes_used();
2996 end_recording_regions();
2998 double non_young_end_time_sec = os::elapsedTime();
2999 _recorded_non_young_cset_choice_time_ms =
3000 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3001 }
3003 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3004 G1CollectorPolicy::record_full_collection_end();
3005 _collectionSetChooser->updateAfterFullCollection();
3006 }
3008 void G1CollectorPolicy_BestRegionsFirst::
3009 expand_if_possible(size_t numRegions) {
3010 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3011 _g1->expand(expansion_bytes);
3012 }
3014 void G1CollectorPolicy_BestRegionsFirst::
3015 record_collection_pause_end() {
3016 G1CollectorPolicy::record_collection_pause_end();
3017 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3018 }