Fri, 06 Feb 2009 01:38:50 +0300
6484959: G1: introduce survivor spaces
6797754: G1: combined bugfix
Summary: Implemented a policy to control G1 survivor space parameters.
Reviewed-by: tonyp, iveresov
1 /*
2 * Copyright 2001-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
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23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectorPolicy.cpp.incl"
28 #define PREDICTIONS_VERBOSE 0
30 // <NEW PREDICTION>
32 // Different defaults for different number of GC threads
33 // They were chosen by running GCOld and SPECjbb on debris with different
34 // numbers of GC threads and choosing them based on the results
36 // all the same
37 static double rs_length_diff_defaults[] = {
38 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
39 };
41 static double cost_per_card_ms_defaults[] = {
42 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
43 };
45 static double cost_per_scan_only_region_ms_defaults[] = {
46 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
47 };
49 // all the same
50 static double fully_young_cards_per_entry_ratio_defaults[] = {
51 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
52 };
54 static double cost_per_entry_ms_defaults[] = {
55 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
56 };
58 static double cost_per_byte_ms_defaults[] = {
59 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
60 };
62 // these should be pretty consistent
63 static double constant_other_time_ms_defaults[] = {
64 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
65 };
68 static double young_other_cost_per_region_ms_defaults[] = {
69 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
70 };
72 static double non_young_other_cost_per_region_ms_defaults[] = {
73 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
74 };
76 // </NEW PREDICTION>
78 G1CollectorPolicy::G1CollectorPolicy() :
79 _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
80 _n_pauses(0),
81 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
82 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
83 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
84 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
85 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
86 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
87 _all_pause_times_ms(new NumberSeq()),
88 _stop_world_start(0.0),
89 _all_stop_world_times_ms(new NumberSeq()),
90 _all_yield_times_ms(new NumberSeq()),
92 _all_mod_union_times_ms(new NumberSeq()),
94 _non_pop_summary(new NonPopSummary()),
95 _pop_summary(new PopSummary()),
96 _non_pop_abandoned_summary(new NonPopAbandonedSummary()),
97 _pop_abandoned_summary(new PopAbandonedSummary()),
99 _cur_clear_ct_time_ms(0.0),
101 _region_num_young(0),
102 _region_num_tenured(0),
103 _prev_region_num_young(0),
104 _prev_region_num_tenured(0),
106 _aux_num(10),
107 _all_aux_times_ms(new NumberSeq[_aux_num]),
108 _cur_aux_start_times_ms(new double[_aux_num]),
109 _cur_aux_times_ms(new double[_aux_num]),
110 _cur_aux_times_set(new bool[_aux_num]),
112 _pop_compute_rc_start(0.0),
113 _pop_evac_start(0.0),
115 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
116 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
117 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
119 // <NEW PREDICTION>
121 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
122 _prev_collection_pause_end_ms(0.0),
123 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
124 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
125 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
126 _cost_per_scan_only_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
127 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
128 _partially_young_cards_per_entry_ratio_seq(
129 new TruncatedSeq(TruncatedSeqLength)),
130 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
131 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
132 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
133 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
134 _cost_per_scan_only_region_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
135 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
136 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
137 _non_young_other_cost_per_region_ms_seq(
138 new TruncatedSeq(TruncatedSeqLength)),
140 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
141 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
142 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
144 _pause_time_target_ms((double) G1MaxPauseTimeMS),
146 // </NEW PREDICTION>
148 _in_young_gc_mode(false),
149 _full_young_gcs(true),
150 _full_young_pause_num(0),
151 _partial_young_pause_num(0),
153 _during_marking(false),
154 _in_marking_window(false),
155 _in_marking_window_im(false),
157 _known_garbage_ratio(0.0),
158 _known_garbage_bytes(0),
160 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
161 _target_pause_time_ms(-1.0),
163 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
165 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
166 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
168 _recent_avg_pause_time_ratio(0.0),
169 _num_markings(0),
170 _n_marks(0),
171 _n_pauses_at_mark_end(0),
173 _all_full_gc_times_ms(new NumberSeq()),
175 _conc_refine_enabled(0),
176 _conc_refine_zero_traversals(0),
177 _conc_refine_max_traversals(0),
178 _conc_refine_current_delta(G1ConcRefineInitialDelta),
180 // G1PausesBtwnConcMark defaults to -1
181 // so the hack is to do the cast QQQ FIXME
182 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
183 _n_marks_since_last_pause(0),
184 _conc_mark_initiated(false),
185 _should_initiate_conc_mark(false),
186 _should_revert_to_full_young_gcs(false),
187 _last_full_young_gc(false),
189 _prev_collection_pause_used_at_end_bytes(0),
191 _collection_set(NULL),
192 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
193 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
194 #endif // _MSC_VER
196 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
197 G1YoungSurvRateNumRegionsSummary)),
198 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
199 G1YoungSurvRateNumRegionsSummary)),
200 // add here any more surv rate groups
201 _recorded_survivor_regions(0),
202 _recorded_survivor_head(NULL),
203 _recorded_survivor_tail(NULL),
204 _survivors_age_table(true)
206 {
207 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
208 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
210 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
211 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
212 _par_last_scan_only_times_ms = new double[_parallel_gc_threads];
213 _par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];
215 _par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
216 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
217 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
219 _par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
220 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
221 _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
223 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
225 _par_last_termination_times_ms = new double[_parallel_gc_threads];
227 // we store the data from the first pass during popularity pauses
228 _pop_par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
229 _pop_par_last_update_rs_times_ms = new double[_parallel_gc_threads];
230 _pop_par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
232 _pop_par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
233 _pop_par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
235 _pop_par_last_closure_app_times_ms = new double[_parallel_gc_threads];
237 // start conservatively
238 _expensive_region_limit_ms = 0.5 * (double) G1MaxPauseTimeMS;
240 // <NEW PREDICTION>
242 int index;
243 if (ParallelGCThreads == 0)
244 index = 0;
245 else if (ParallelGCThreads > 8)
246 index = 7;
247 else
248 index = ParallelGCThreads - 1;
250 _pending_card_diff_seq->add(0.0);
251 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
252 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
253 _cost_per_scan_only_region_ms_seq->add(
254 cost_per_scan_only_region_ms_defaults[index]);
255 _fully_young_cards_per_entry_ratio_seq->add(
256 fully_young_cards_per_entry_ratio_defaults[index]);
257 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
258 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
259 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
260 _young_other_cost_per_region_ms_seq->add(
261 young_other_cost_per_region_ms_defaults[index]);
262 _non_young_other_cost_per_region_ms_seq->add(
263 non_young_other_cost_per_region_ms_defaults[index]);
265 // </NEW PREDICTION>
267 double time_slice = (double) G1TimeSliceMS / 1000.0;
268 double max_gc_time = (double) G1MaxPauseTimeMS / 1000.0;
269 guarantee(max_gc_time < time_slice,
270 "Max GC time should not be greater than the time slice");
271 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
272 _sigma = (double) G1ConfidencePerc / 100.0;
274 // start conservatively (around 50ms is about right)
275 _concurrent_mark_init_times_ms->add(0.05);
276 _concurrent_mark_remark_times_ms->add(0.05);
277 _concurrent_mark_cleanup_times_ms->add(0.20);
278 _tenuring_threshold = MaxTenuringThreshold;
280 if (G1UseSurvivorSpace) {
281 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
282 // fixed, then _max_survivor_regions will be calculated at
283 // calculate_young_list_target_config diring initialization
284 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
285 } else {
286 _max_survivor_regions = 0;
287 }
289 initialize_all();
290 }
292 // Increment "i", mod "len"
293 static void inc_mod(int& i, int len) {
294 i++; if (i == len) i = 0;
295 }
297 void G1CollectorPolicy::initialize_flags() {
298 set_min_alignment(HeapRegion::GrainBytes);
299 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
300 CollectorPolicy::initialize_flags();
301 }
303 void G1CollectorPolicy::init() {
304 // Set aside an initial future to_space.
305 _g1 = G1CollectedHeap::heap();
306 size_t regions = Universe::heap()->capacity() / HeapRegion::GrainBytes;
308 assert(Heap_lock->owned_by_self(), "Locking discipline.");
310 if (G1SteadyStateUsed < 50) {
311 vm_exit_during_initialization("G1SteadyStateUsed must be at least 50%.");
312 }
313 if (UseConcMarkSweepGC) {
314 vm_exit_during_initialization("-XX:+UseG1GC is incompatible with "
315 "-XX:+UseConcMarkSweepGC.");
316 }
318 initialize_gc_policy_counters();
320 if (G1Gen) {
321 _in_young_gc_mode = true;
323 if (G1YoungGenSize == 0) {
324 set_adaptive_young_list_length(true);
325 _young_list_fixed_length = 0;
326 } else {
327 set_adaptive_young_list_length(false);
328 _young_list_fixed_length = (G1YoungGenSize / HeapRegion::GrainBytes);
329 }
330 _free_regions_at_end_of_collection = _g1->free_regions();
331 _scan_only_regions_at_end_of_collection = 0;
332 calculate_young_list_min_length();
333 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
334 calculate_young_list_target_config();
335 } else {
336 _young_list_fixed_length = 0;
337 _in_young_gc_mode = false;
338 }
339 }
341 // Create the jstat counters for the policy.
342 void G1CollectorPolicy::initialize_gc_policy_counters()
343 {
344 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
345 }
347 void G1CollectorPolicy::calculate_young_list_min_length() {
348 _young_list_min_length = 0;
350 if (!adaptive_young_list_length())
351 return;
353 if (_alloc_rate_ms_seq->num() > 3) {
354 double now_sec = os::elapsedTime();
355 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
356 double alloc_rate_ms = predict_alloc_rate_ms();
357 int min_regions = (int) ceil(alloc_rate_ms * when_ms);
358 int current_region_num = (int) _g1->young_list_length();
359 _young_list_min_length = min_regions + current_region_num;
360 }
361 }
363 void G1CollectorPolicy::calculate_young_list_target_config() {
364 if (adaptive_young_list_length()) {
365 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
366 calculate_young_list_target_config(rs_lengths);
367 } else {
368 if (full_young_gcs())
369 _young_list_target_length = _young_list_fixed_length;
370 else
371 _young_list_target_length = _young_list_fixed_length / 2;
372 _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
373 size_t so_length = calculate_optimal_so_length(_young_list_target_length);
374 guarantee( so_length < _young_list_target_length, "invariant" );
375 _young_list_so_prefix_length = so_length;
376 }
377 calculate_survivors_policy();
378 }
380 // This method calculate the optimal scan-only set for a fixed young
381 // gen size. I couldn't work out how to reuse the more elaborate one,
382 // i.e. calculate_young_list_target_config(rs_length), as the loops are
383 // fundamentally different (the other one finds a config for different
384 // S-O lengths, whereas here we need to do the opposite).
385 size_t G1CollectorPolicy::calculate_optimal_so_length(
386 size_t young_list_length) {
387 if (!G1UseScanOnlyPrefix)
388 return 0;
390 if (_all_pause_times_ms->num() < 3) {
391 // we won't use a scan-only set at the beginning to allow the rest
392 // of the predictors to warm up
393 return 0;
394 }
396 if (_cost_per_scan_only_region_ms_seq->num() < 3) {
397 // then, we'll only set the S-O set to 1 for a little bit of time,
398 // to get enough information on the scanning cost
399 return 1;
400 }
402 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
403 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
404 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
405 size_t scanned_cards;
406 if (full_young_gcs())
407 scanned_cards = predict_young_card_num(adj_rs_lengths);
408 else
409 scanned_cards = predict_non_young_card_num(adj_rs_lengths);
410 double base_time_ms = predict_base_elapsed_time_ms(pending_cards,
411 scanned_cards);
413 size_t so_length = 0;
414 double max_gc_eff = 0.0;
415 for (size_t i = 0; i < young_list_length; ++i) {
416 double gc_eff = 0.0;
417 double pause_time_ms = 0.0;
418 predict_gc_eff(young_list_length, i, base_time_ms,
419 &gc_eff, &pause_time_ms);
420 if (gc_eff > max_gc_eff) {
421 max_gc_eff = gc_eff;
422 so_length = i;
423 }
424 }
426 // set it to 95% of the optimal to make sure we sample the "area"
427 // around the optimal length to get up-to-date survival rate data
428 return so_length * 950 / 1000;
429 }
431 // This is a really cool piece of code! It finds the best
432 // target configuration (young length / scan-only prefix length) so
433 // that GC efficiency is maximized and that we also meet a pause
434 // time. It's a triple nested loop. These loops are explained below
435 // from the inside-out :-)
436 //
437 // (a) The innermost loop will try to find the optimal young length
438 // for a fixed S-O length. It uses a binary search to speed up the
439 // process. We assume that, for a fixed S-O length, as we add more
440 // young regions to the CSet, the GC efficiency will only go up (I'll
441 // skip the proof). So, using a binary search to optimize this process
442 // makes perfect sense.
443 //
444 // (b) The middle loop will fix the S-O length before calling the
445 // innermost one. It will vary it between two parameters, increasing
446 // it by a given increment.
447 //
448 // (c) The outermost loop will call the middle loop three times.
449 // (1) The first time it will explore all possible S-O length values
450 // from 0 to as large as it can get, using a coarse increment (to
451 // quickly "home in" to where the optimal seems to be).
452 // (2) The second time it will explore the values around the optimal
453 // that was found by the first iteration using a fine increment.
454 // (3) Once the optimal config has been determined by the second
455 // iteration, we'll redo the calculation, but setting the S-O length
456 // to 95% of the optimal to make sure we sample the "area"
457 // around the optimal length to get up-to-date survival rate data
458 //
459 // Termination conditions for the iterations are several: the pause
460 // time is over the limit, we do not have enough to-space, etc.
462 void G1CollectorPolicy::calculate_young_list_target_config(size_t rs_lengths) {
463 guarantee( adaptive_young_list_length(), "pre-condition" );
465 double start_time_sec = os::elapsedTime();
466 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1MinReservePerc);
467 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
468 size_t reserve_regions =
469 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
471 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
472 // we are in fully-young mode and there are free regions in the heap
474 double survivor_regions_evac_time =
475 predict_survivor_regions_evac_time();
477 size_t min_so_length = 0;
478 size_t max_so_length = 0;
480 if (G1UseScanOnlyPrefix) {
481 if (_all_pause_times_ms->num() < 3) {
482 // we won't use a scan-only set at the beginning to allow the rest
483 // of the predictors to warm up
484 min_so_length = 0;
485 max_so_length = 0;
486 } else if (_cost_per_scan_only_region_ms_seq->num() < 3) {
487 // then, we'll only set the S-O set to 1 for a little bit of time,
488 // to get enough information on the scanning cost
489 min_so_length = 1;
490 max_so_length = 1;
491 } else if (_in_marking_window || _last_full_young_gc) {
492 // no S-O prefix during a marking phase either, as at the end
493 // of the marking phase we'll have to use a very small young
494 // length target to fill up the rest of the CSet with
495 // non-young regions and, if we have lots of scan-only regions
496 // left-over, we will not be able to add any more non-young
497 // regions.
498 min_so_length = 0;
499 max_so_length = 0;
500 } else {
501 // this is the common case; we'll never reach the maximum, we
502 // one of the end conditions will fire well before that
503 // (hopefully!)
504 min_so_length = 0;
505 max_so_length = _free_regions_at_end_of_collection - 1;
506 }
507 } else {
508 // no S-O prefix, as the switch is not set, but we still need to
509 // do one iteration to calculate the best young target that
510 // meets the pause time; this way we reuse the same code instead
511 // of replicating it
512 min_so_length = 0;
513 max_so_length = 0;
514 }
516 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
517 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
518 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
519 size_t scanned_cards;
520 if (full_young_gcs())
521 scanned_cards = predict_young_card_num(adj_rs_lengths);
522 else
523 scanned_cards = predict_non_young_card_num(adj_rs_lengths);
524 // calculate this once, so that we don't have to recalculate it in
525 // the innermost loop
526 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
527 + survivor_regions_evac_time;
528 // the result
529 size_t final_young_length = 0;
530 size_t final_so_length = 0;
531 double final_gc_eff = 0.0;
532 // we'll also keep track of how many times we go into the inner loop
533 // this is for profiling reasons
534 size_t calculations = 0;
536 // this determines which of the three iterations the outer loop is in
537 typedef enum {
538 pass_type_coarse,
539 pass_type_fine,
540 pass_type_final
541 } pass_type_t;
543 // range of the outer loop's iteration
544 size_t from_so_length = min_so_length;
545 size_t to_so_length = max_so_length;
546 guarantee( from_so_length <= to_so_length, "invariant" );
548 // this will keep the S-O length that's found by the second
549 // iteration of the outer loop; we'll keep it just in case the third
550 // iteration fails to find something
551 size_t fine_so_length = 0;
553 // the increment step for the coarse (first) iteration
554 size_t so_coarse_increments = 5;
556 // the common case, we'll start with the coarse iteration
557 pass_type_t pass = pass_type_coarse;
558 size_t so_length_incr = so_coarse_increments;
560 if (from_so_length == to_so_length) {
561 // not point in doing the coarse iteration, we'll go directly into
562 // the fine one (we essentially trying to find the optimal young
563 // length for a fixed S-O length).
564 so_length_incr = 1;
565 pass = pass_type_final;
566 } else if (to_so_length - from_so_length < 3 * so_coarse_increments) {
567 // again, the range is too short so no point in foind the coarse
568 // iteration either
569 so_length_incr = 1;
570 pass = pass_type_fine;
571 }
573 bool done = false;
574 // this is the outermost loop
575 while (!done) {
576 #ifdef TRACE_CALC_YOUNG_CONFIG
577 // leave this in for debugging, just in case
578 gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT
579 ", incr " SIZE_FORMAT ", pass %s",
580 from_so_length, to_so_length, so_length_incr,
581 (pass == pass_type_coarse) ? "coarse" :
582 (pass == pass_type_fine) ? "fine" : "final");
583 #endif // TRACE_CALC_YOUNG_CONFIG
585 size_t so_length = from_so_length;
586 size_t init_free_regions =
587 MAX2((size_t)0,
588 _free_regions_at_end_of_collection +
589 _scan_only_regions_at_end_of_collection - reserve_regions);
591 // this determines whether a configuration was found
592 bool gc_eff_set = false;
593 // this is the middle loop
594 while (so_length <= to_so_length) {
595 // base time, which excludes region-related time; again we
596 // calculate it once to avoid recalculating it in the
597 // innermost loop
598 double base_time_with_so_ms =
599 base_time_ms + predict_scan_only_time_ms(so_length);
600 // it's already over the pause target, go around
601 if (base_time_with_so_ms > target_pause_time_ms)
602 break;
604 size_t starting_young_length = so_length+1;
606 // we make sure that the short young length that makes sense
607 // (one more than the S-O length) is feasible
608 size_t min_young_length = starting_young_length;
609 double min_gc_eff;
610 bool min_ok;
611 ++calculations;
612 min_ok = predict_gc_eff(min_young_length, so_length,
613 base_time_with_so_ms,
614 init_free_regions, target_pause_time_ms,
615 &min_gc_eff);
617 if (min_ok) {
618 // the shortest young length is indeed feasible; we'll know
619 // set up the max young length and we'll do a binary search
620 // between min_young_length and max_young_length
621 size_t max_young_length = _free_regions_at_end_of_collection - 1;
622 double max_gc_eff = 0.0;
623 bool max_ok = false;
625 // the innermost loop! (finally!)
626 while (max_young_length > min_young_length) {
627 // we'll make sure that min_young_length is always at a
628 // feasible config
629 guarantee( min_ok, "invariant" );
631 ++calculations;
632 max_ok = predict_gc_eff(max_young_length, so_length,
633 base_time_with_so_ms,
634 init_free_regions, target_pause_time_ms,
635 &max_gc_eff);
637 size_t diff = (max_young_length - min_young_length) / 2;
638 if (max_ok) {
639 min_young_length = max_young_length;
640 min_gc_eff = max_gc_eff;
641 min_ok = true;
642 }
643 max_young_length = min_young_length + diff;
644 }
646 // the innermost loop found a config
647 guarantee( min_ok, "invariant" );
648 if (min_gc_eff > final_gc_eff) {
649 // it's the best config so far, so we'll keep it
650 final_gc_eff = min_gc_eff;
651 final_young_length = min_young_length;
652 final_so_length = so_length;
653 gc_eff_set = true;
654 }
655 }
657 // incremental the fixed S-O length and go around
658 so_length += so_length_incr;
659 }
661 // this is the end of the outermost loop and we need to decide
662 // what to do during the next iteration
663 if (pass == pass_type_coarse) {
664 // we just did the coarse pass (first iteration)
666 if (!gc_eff_set)
667 // we didn't find a feasible config so we'll just bail out; of
668 // course, it might be the case that we missed it; but I'd say
669 // it's a bit unlikely
670 done = true;
671 else {
672 // We did find a feasible config with optimal GC eff during
673 // the first pass. So the second pass we'll only consider the
674 // S-O lengths around that config with a fine increment.
676 guarantee( so_length_incr == so_coarse_increments, "invariant" );
677 guarantee( final_so_length >= min_so_length, "invariant" );
679 #ifdef TRACE_CALC_YOUNG_CONFIG
680 // leave this in for debugging, just in case
681 gclog_or_tty->print_cr(" coarse pass: SO length " SIZE_FORMAT,
682 final_so_length);
683 #endif // TRACE_CALC_YOUNG_CONFIG
685 from_so_length =
686 (final_so_length - min_so_length > so_coarse_increments) ?
687 final_so_length - so_coarse_increments + 1 : min_so_length;
688 to_so_length =
689 (max_so_length - final_so_length > so_coarse_increments) ?
690 final_so_length + so_coarse_increments - 1 : max_so_length;
692 pass = pass_type_fine;
693 so_length_incr = 1;
694 }
695 } else if (pass == pass_type_fine) {
696 // we just finished the second pass
698 if (!gc_eff_set) {
699 // we didn't find a feasible config (yes, it's possible;
700 // notice that, sometimes, we go directly into the fine
701 // iteration and skip the coarse one) so we bail out
702 done = true;
703 } else {
704 // We did find a feasible config with optimal GC eff
705 guarantee( so_length_incr == 1, "invariant" );
707 if (final_so_length == 0) {
708 // The config is of an empty S-O set, so we'll just bail out
709 done = true;
710 } else {
711 // we'll go around once more, setting the S-O length to 95%
712 // of the optimal
713 size_t new_so_length = 950 * final_so_length / 1000;
715 #ifdef TRACE_CALC_YOUNG_CONFIG
716 // leave this in for debugging, just in case
717 gclog_or_tty->print_cr(" fine pass: SO length " SIZE_FORMAT
718 ", setting it to " SIZE_FORMAT,
719 final_so_length, new_so_length);
720 #endif // TRACE_CALC_YOUNG_CONFIG
722 from_so_length = new_so_length;
723 to_so_length = new_so_length;
724 fine_so_length = final_so_length;
726 pass = pass_type_final;
727 }
728 }
729 } else if (pass == pass_type_final) {
730 // we just finished the final (third) pass
732 if (!gc_eff_set)
733 // we didn't find a feasible config, so we'll just use the one
734 // we found during the second pass, which we saved
735 final_so_length = fine_so_length;
737 // and we're done!
738 done = true;
739 } else {
740 guarantee( false, "should never reach here" );
741 }
743 // we now go around the outermost loop
744 }
746 // we should have at least one region in the target young length
747 _young_list_target_length =
748 MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
749 if (final_so_length >= final_young_length)
750 // and we need to ensure that the S-O length is not greater than
751 // the target young length (this is being a bit careful)
752 final_so_length = 0;
753 _young_list_so_prefix_length = final_so_length;
754 guarantee( !_in_marking_window || !_last_full_young_gc ||
755 _young_list_so_prefix_length == 0, "invariant" );
757 // let's keep an eye of how long we spend on this calculation
758 // right now, I assume that we'll print it when we need it; we
759 // should really adde it to the breakdown of a pause
760 double end_time_sec = os::elapsedTime();
761 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
763 #ifdef TRACE_CALC_YOUNG_CONFIG
764 // leave this in for debugging, just in case
765 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT
766 ", SO = " SIZE_FORMAT ", "
767 "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "
768 SIZE_FORMAT SIZE_FORMAT,
769 target_pause_time_ms,
770 _young_list_target_length - _young_list_so_prefix_length,
771 _young_list_so_prefix_length,
772 elapsed_time_ms,
773 calculations,
774 full_young_gcs() ? "full" : "partial",
775 should_initiate_conc_mark() ? " i-m" : "",
776 _in_marking_window,
777 _in_marking_window_im);
778 #endif // TRACE_CALC_YOUNG_CONFIG
780 if (_young_list_target_length < _young_list_min_length) {
781 // bummer; this means that, if we do a pause when the optimal
782 // config dictates, we'll violate the pause spacing target (the
783 // min length was calculate based on the application's current
784 // alloc rate);
786 // so, we have to bite the bullet, and allocate the minimum
787 // number. We'll violate our target, but we just can't meet it.
789 size_t so_length = 0;
790 // a note further up explains why we do not want an S-O length
791 // during marking
792 if (!_in_marking_window && !_last_full_young_gc)
793 // but we can still try to see whether we can find an optimal
794 // S-O length
795 so_length = calculate_optimal_so_length(_young_list_min_length);
797 #ifdef TRACE_CALC_YOUNG_CONFIG
798 // leave this in for debugging, just in case
799 gclog_or_tty->print_cr("adjusted target length from "
800 SIZE_FORMAT " to " SIZE_FORMAT
801 ", SO " SIZE_FORMAT,
802 _young_list_target_length, _young_list_min_length,
803 so_length);
804 #endif // TRACE_CALC_YOUNG_CONFIG
806 _young_list_target_length =
807 MAX2(_young_list_min_length, (size_t)1);
808 _young_list_so_prefix_length = so_length;
809 }
810 } else {
811 // we are in a partially-young mode or we've run out of regions (due
812 // to evacuation failure)
814 #ifdef TRACE_CALC_YOUNG_CONFIG
815 // leave this in for debugging, just in case
816 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
817 ", SO " SIZE_FORMAT,
818 _young_list_min_length, 0);
819 #endif // TRACE_CALC_YOUNG_CONFIG
821 // we'll do the pause as soon as possible and with no S-O prefix
822 // (see above for the reasons behind the latter)
823 _young_list_target_length =
824 MAX2(_young_list_min_length, (size_t) 1);
825 _young_list_so_prefix_length = 0;
826 }
828 _rs_lengths_prediction = rs_lengths;
829 }
831 // This is used by: calculate_optimal_so_length(length). It returns
832 // the GC eff and predicted pause time for a particular config
833 void
834 G1CollectorPolicy::predict_gc_eff(size_t young_length,
835 size_t so_length,
836 double base_time_ms,
837 double* ret_gc_eff,
838 double* ret_pause_time_ms) {
839 double so_time_ms = predict_scan_only_time_ms(so_length);
840 double accum_surv_rate_adj = 0.0;
841 if (so_length > 0)
842 accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
843 double accum_surv_rate =
844 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
845 size_t bytes_to_copy =
846 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
847 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
848 double young_other_time_ms =
849 predict_young_other_time_ms(young_length - so_length);
850 double pause_time_ms =
851 base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;
852 size_t reclaimed_bytes =
853 (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
854 double gc_eff = (double) reclaimed_bytes / pause_time_ms;
856 *ret_gc_eff = gc_eff;
857 *ret_pause_time_ms = pause_time_ms;
858 }
860 // This is used by: calculate_young_list_target_config(rs_length). It
861 // returns the GC eff of a particular config. It returns false if that
862 // config violates any of the end conditions of the search in the
863 // calling method, or true upon success. The end conditions were put
864 // here since it's called twice and it was best not to replicate them
865 // in the caller. Also, passing the parameteres avoids having to
866 // recalculate them in the innermost loop.
867 bool
868 G1CollectorPolicy::predict_gc_eff(size_t young_length,
869 size_t so_length,
870 double base_time_with_so_ms,
871 size_t init_free_regions,
872 double target_pause_time_ms,
873 double* ret_gc_eff) {
874 *ret_gc_eff = 0.0;
876 if (young_length >= init_free_regions)
877 // end condition 1: not enough space for the young regions
878 return false;
880 double accum_surv_rate_adj = 0.0;
881 if (so_length > 0)
882 accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
883 double accum_surv_rate =
884 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
885 size_t bytes_to_copy =
886 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
887 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
888 double young_other_time_ms =
889 predict_young_other_time_ms(young_length - so_length);
890 double pause_time_ms =
891 base_time_with_so_ms + copy_time_ms + young_other_time_ms;
893 if (pause_time_ms > target_pause_time_ms)
894 // end condition 2: over the target pause time
895 return false;
897 size_t reclaimed_bytes =
898 (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
899 size_t free_bytes =
900 (init_free_regions - young_length) * HeapRegion::GrainBytes;
902 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
903 // end condition 3: out of to-space (conservatively)
904 return false;
906 // success!
907 double gc_eff = (double) reclaimed_bytes / pause_time_ms;
908 *ret_gc_eff = gc_eff;
910 return true;
911 }
913 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
914 double survivor_regions_evac_time = 0.0;
915 for (HeapRegion * r = _recorded_survivor_head;
916 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
917 r = r->get_next_young_region()) {
918 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
919 }
920 return survivor_regions_evac_time;
921 }
923 void G1CollectorPolicy::check_prediction_validity() {
924 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
926 size_t rs_lengths = _g1->young_list_sampled_rs_lengths();
927 if (rs_lengths > _rs_lengths_prediction) {
928 // add 10% to avoid having to recalculate often
929 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
930 calculate_young_list_target_config(rs_lengths_prediction);
931 }
932 }
934 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
935 bool is_tlab,
936 bool* gc_overhead_limit_was_exceeded) {
937 guarantee(false, "Not using this policy feature yet.");
938 return NULL;
939 }
941 // This method controls how a collector handles one or more
942 // of its generations being fully allocated.
943 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
944 bool is_tlab) {
945 guarantee(false, "Not using this policy feature yet.");
946 return NULL;
947 }
950 #ifndef PRODUCT
951 bool G1CollectorPolicy::verify_young_ages() {
952 HeapRegion* head = _g1->young_list_first_region();
953 return
954 verify_young_ages(head, _short_lived_surv_rate_group);
955 // also call verify_young_ages on any additional surv rate groups
956 }
958 bool
959 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
960 SurvRateGroup *surv_rate_group) {
961 guarantee( surv_rate_group != NULL, "pre-condition" );
963 const char* name = surv_rate_group->name();
964 bool ret = true;
965 int prev_age = -1;
967 for (HeapRegion* curr = head;
968 curr != NULL;
969 curr = curr->get_next_young_region()) {
970 SurvRateGroup* group = curr->surv_rate_group();
971 if (group == NULL && !curr->is_survivor()) {
972 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
973 ret = false;
974 }
976 if (surv_rate_group == group) {
977 int age = curr->age_in_surv_rate_group();
979 if (age < 0) {
980 gclog_or_tty->print_cr("## %s: encountered negative age", name);
981 ret = false;
982 }
984 if (age <= prev_age) {
985 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
986 "(%d, %d)", name, age, prev_age);
987 ret = false;
988 }
989 prev_age = age;
990 }
991 }
993 return ret;
994 }
995 #endif // PRODUCT
997 void G1CollectorPolicy::record_full_collection_start() {
998 _cur_collection_start_sec = os::elapsedTime();
999 // Release the future to-space so that it is available for compaction into.
1000 _g1->set_full_collection();
1001 }
1003 void G1CollectorPolicy::record_full_collection_end() {
1004 // Consider this like a collection pause for the purposes of allocation
1005 // since last pause.
1006 double end_sec = os::elapsedTime();
1007 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
1008 double full_gc_time_ms = full_gc_time_sec * 1000.0;
1010 checkpoint_conc_overhead();
1012 _all_full_gc_times_ms->add(full_gc_time_ms);
1014 update_recent_gc_times(end_sec, full_gc_time_sec);
1016 _g1->clear_full_collection();
1018 // "Nuke" the heuristics that control the fully/partially young GC
1019 // transitions and make sure we start with fully young GCs after the
1020 // Full GC.
1021 set_full_young_gcs(true);
1022 _last_full_young_gc = false;
1023 _should_revert_to_full_young_gcs = false;
1024 _should_initiate_conc_mark = false;
1025 _known_garbage_bytes = 0;
1026 _known_garbage_ratio = 0.0;
1027 _in_marking_window = false;
1028 _in_marking_window_im = false;
1030 _short_lived_surv_rate_group->record_scan_only_prefix(0);
1031 _short_lived_surv_rate_group->start_adding_regions();
1032 // also call this on any additional surv rate groups
1034 record_survivor_regions(0, NULL, NULL);
1036 _prev_region_num_young = _region_num_young;
1037 _prev_region_num_tenured = _region_num_tenured;
1039 _free_regions_at_end_of_collection = _g1->free_regions();
1040 _scan_only_regions_at_end_of_collection = 0;
1041 // Reset survivors SurvRateGroup.
1042 _survivor_surv_rate_group->reset();
1043 calculate_young_list_min_length();
1044 calculate_young_list_target_config();
1045 }
1047 void G1CollectorPolicy::record_pop_compute_rc_start() {
1048 _pop_compute_rc_start = os::elapsedTime();
1049 }
1050 void G1CollectorPolicy::record_pop_compute_rc_end() {
1051 double ms = (os::elapsedTime() - _pop_compute_rc_start)*1000.0;
1052 _cur_popular_compute_rc_time_ms = ms;
1053 _pop_compute_rc_start = 0.0;
1054 }
1055 void G1CollectorPolicy::record_pop_evac_start() {
1056 _pop_evac_start = os::elapsedTime();
1057 }
1058 void G1CollectorPolicy::record_pop_evac_end() {
1059 double ms = (os::elapsedTime() - _pop_evac_start)*1000.0;
1060 _cur_popular_evac_time_ms = ms;
1061 _pop_evac_start = 0.0;
1062 }
1064 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
1065 _bytes_in_to_space_before_gc += bytes;
1066 }
1068 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
1069 _bytes_in_to_space_after_gc += bytes;
1070 }
1072 void G1CollectorPolicy::record_stop_world_start() {
1073 _stop_world_start = os::elapsedTime();
1074 }
1076 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
1077 size_t start_used) {
1078 if (PrintGCDetails) {
1079 gclog_or_tty->stamp(PrintGCTimeStamps);
1080 gclog_or_tty->print("[GC pause");
1081 if (in_young_gc_mode())
1082 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
1083 }
1085 assert(_g1->used_regions() == _g1->recalculate_used_regions(),
1086 "sanity");
1088 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
1089 _all_stop_world_times_ms->add(s_w_t_ms);
1090 _stop_world_start = 0.0;
1092 _cur_collection_start_sec = start_time_sec;
1093 _cur_collection_pause_used_at_start_bytes = start_used;
1094 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
1095 _pending_cards = _g1->pending_card_num();
1096 _max_pending_cards = _g1->max_pending_card_num();
1098 _bytes_in_to_space_before_gc = 0;
1099 _bytes_in_to_space_after_gc = 0;
1100 _bytes_in_collection_set_before_gc = 0;
1102 #ifdef DEBUG
1103 // initialise these to something well known so that we can spot
1104 // if they are not set properly
1106 for (int i = 0; i < _parallel_gc_threads; ++i) {
1107 _par_last_ext_root_scan_times_ms[i] = -666.0;
1108 _par_last_mark_stack_scan_times_ms[i] = -666.0;
1109 _par_last_scan_only_times_ms[i] = -666.0;
1110 _par_last_scan_only_regions_scanned[i] = -666.0;
1111 _par_last_update_rs_start_times_ms[i] = -666.0;
1112 _par_last_update_rs_times_ms[i] = -666.0;
1113 _par_last_update_rs_processed_buffers[i] = -666.0;
1114 _par_last_scan_rs_start_times_ms[i] = -666.0;
1115 _par_last_scan_rs_times_ms[i] = -666.0;
1116 _par_last_scan_new_refs_times_ms[i] = -666.0;
1117 _par_last_obj_copy_times_ms[i] = -666.0;
1118 _par_last_termination_times_ms[i] = -666.0;
1120 _pop_par_last_update_rs_start_times_ms[i] = -666.0;
1121 _pop_par_last_update_rs_times_ms[i] = -666.0;
1122 _pop_par_last_update_rs_processed_buffers[i] = -666.0;
1123 _pop_par_last_scan_rs_start_times_ms[i] = -666.0;
1124 _pop_par_last_scan_rs_times_ms[i] = -666.0;
1125 _pop_par_last_closure_app_times_ms[i] = -666.0;
1126 }
1127 #endif
1129 for (int i = 0; i < _aux_num; ++i) {
1130 _cur_aux_times_ms[i] = 0.0;
1131 _cur_aux_times_set[i] = false;
1132 }
1134 _satb_drain_time_set = false;
1135 _last_satb_drain_processed_buffers = -1;
1137 if (in_young_gc_mode())
1138 _last_young_gc_full = false;
1141 // do that for any other surv rate groups
1142 _short_lived_surv_rate_group->stop_adding_regions();
1143 size_t short_lived_so_length = _young_list_so_prefix_length;
1144 _short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);
1145 tag_scan_only(short_lived_so_length);
1147 if (G1UseSurvivorSpace) {
1148 _survivors_age_table.clear();
1149 }
1151 assert( verify_young_ages(), "region age verification" );
1152 }
1154 void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {
1155 // done in a way that it can be extended for other surv rate groups too...
1157 HeapRegion* head = _g1->young_list_first_region();
1158 bool finished_short_lived = (short_lived_scan_only_length == 0);
1160 if (finished_short_lived)
1161 return;
1163 for (HeapRegion* curr = head;
1164 curr != NULL;
1165 curr = curr->get_next_young_region()) {
1166 SurvRateGroup* surv_rate_group = curr->surv_rate_group();
1167 int age = curr->age_in_surv_rate_group();
1169 if (surv_rate_group == _short_lived_surv_rate_group) {
1170 if ((size_t)age < short_lived_scan_only_length)
1171 curr->set_scan_only();
1172 else
1173 finished_short_lived = true;
1174 }
1177 if (finished_short_lived)
1178 return;
1179 }
1181 guarantee( false, "we should never reach here" );
1182 }
1184 void G1CollectorPolicy::record_popular_pause_preamble_start() {
1185 _cur_popular_preamble_start_ms = os::elapsedTime() * 1000.0;
1186 }
1188 void G1CollectorPolicy::record_popular_pause_preamble_end() {
1189 _cur_popular_preamble_time_ms =
1190 (os::elapsedTime() * 1000.0) - _cur_popular_preamble_start_ms;
1192 // copy the recorded statistics of the first pass to temporary arrays
1193 for (int i = 0; i < _parallel_gc_threads; ++i) {
1194 _pop_par_last_update_rs_start_times_ms[i] = _par_last_update_rs_start_times_ms[i];
1195 _pop_par_last_update_rs_times_ms[i] = _par_last_update_rs_times_ms[i];
1196 _pop_par_last_update_rs_processed_buffers[i] = _par_last_update_rs_processed_buffers[i];
1197 _pop_par_last_scan_rs_start_times_ms[i] = _par_last_scan_rs_start_times_ms[i];
1198 _pop_par_last_scan_rs_times_ms[i] = _par_last_scan_rs_times_ms[i];
1199 _pop_par_last_closure_app_times_ms[i] = _par_last_obj_copy_times_ms[i];
1200 }
1201 }
1203 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
1204 _mark_closure_time_ms = mark_closure_time_ms;
1205 }
1207 void G1CollectorPolicy::record_concurrent_mark_init_start() {
1208 _mark_init_start_sec = os::elapsedTime();
1209 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
1210 }
1212 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
1213 mark_init_elapsed_time_ms) {
1214 _during_marking = true;
1215 _should_initiate_conc_mark = false;
1216 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
1217 }
1219 void G1CollectorPolicy::record_concurrent_mark_init_end() {
1220 double end_time_sec = os::elapsedTime();
1221 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
1222 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
1223 checkpoint_conc_overhead();
1224 record_concurrent_mark_init_end_pre(elapsed_time_ms);
1226 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
1227 }
1229 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
1230 _mark_remark_start_sec = os::elapsedTime();
1231 _during_marking = false;
1232 }
1234 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
1235 double end_time_sec = os::elapsedTime();
1236 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
1237 checkpoint_conc_overhead();
1238 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
1239 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1240 _prev_collection_pause_end_ms += elapsed_time_ms;
1242 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
1243 }
1245 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
1246 _mark_cleanup_start_sec = os::elapsedTime();
1247 }
1249 void
1250 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
1251 size_t max_live_bytes) {
1252 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
1253 record_concurrent_mark_cleanup_end_work2();
1254 }
1256 void
1257 G1CollectorPolicy::
1258 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
1259 size_t max_live_bytes) {
1260 if (_n_marks < 2) _n_marks++;
1261 if (G1PolicyVerbose > 0)
1262 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
1263 " (of " SIZE_FORMAT " MB heap).",
1264 max_live_bytes/M, _g1->capacity()/M);
1265 }
1267 // The important thing about this is that it includes "os::elapsedTime".
1268 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
1269 checkpoint_conc_overhead();
1270 double end_time_sec = os::elapsedTime();
1271 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
1272 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1273 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1274 _prev_collection_pause_end_ms += elapsed_time_ms;
1276 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
1278 _num_markings++;
1280 // We did a marking, so reset the "since_last_mark" variables.
1281 double considerConcMarkCost = 1.0;
1282 // If there are available processors, concurrent activity is free...
1283 if (Threads::number_of_non_daemon_threads() * 2 <
1284 os::active_processor_count()) {
1285 considerConcMarkCost = 0.0;
1286 }
1287 _n_pauses_at_mark_end = _n_pauses;
1288 _n_marks_since_last_pause++;
1289 _conc_mark_initiated = false;
1290 }
1292 void
1293 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
1294 if (in_young_gc_mode()) {
1295 _should_revert_to_full_young_gcs = false;
1296 _last_full_young_gc = true;
1297 _in_marking_window = false;
1298 if (adaptive_young_list_length())
1299 calculate_young_list_target_config();
1300 }
1301 }
1303 void G1CollectorPolicy::record_concurrent_pause() {
1304 if (_stop_world_start > 0.0) {
1305 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
1306 _all_yield_times_ms->add(yield_ms);
1307 }
1308 }
1310 void G1CollectorPolicy::record_concurrent_pause_end() {
1311 }
1313 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
1314 _cur_CH_strong_roots_end_sec = os::elapsedTime();
1315 _cur_CH_strong_roots_dur_ms =
1316 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
1317 }
1319 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
1320 _cur_G1_strong_roots_end_sec = os::elapsedTime();
1321 _cur_G1_strong_roots_dur_ms =
1322 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
1323 }
1325 template<class T>
1326 T sum_of(T* sum_arr, int start, int n, int N) {
1327 T sum = (T)0;
1328 for (int i = 0; i < n; i++) {
1329 int j = (start + i) % N;
1330 sum += sum_arr[j];
1331 }
1332 return sum;
1333 }
1335 void G1CollectorPolicy::print_par_stats (int level,
1336 const char* str,
1337 double* data,
1338 bool summary) {
1339 double min = data[0], max = data[0];
1340 double total = 0.0;
1341 int j;
1342 for (j = 0; j < level; ++j)
1343 gclog_or_tty->print(" ");
1344 gclog_or_tty->print("[%s (ms):", str);
1345 for (uint i = 0; i < ParallelGCThreads; ++i) {
1346 double val = data[i];
1347 if (val < min)
1348 min = val;
1349 if (val > max)
1350 max = val;
1351 total += val;
1352 gclog_or_tty->print(" %3.1lf", val);
1353 }
1354 if (summary) {
1355 gclog_or_tty->print_cr("");
1356 double avg = total / (double) ParallelGCThreads;
1357 gclog_or_tty->print(" ");
1358 for (j = 0; j < level; ++j)
1359 gclog_or_tty->print(" ");
1360 gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
1361 avg, min, max);
1362 }
1363 gclog_or_tty->print_cr("]");
1364 }
1366 void G1CollectorPolicy::print_par_buffers (int level,
1367 const char* str,
1368 double* data,
1369 bool summary) {
1370 double min = data[0], max = data[0];
1371 double total = 0.0;
1372 int j;
1373 for (j = 0; j < level; ++j)
1374 gclog_or_tty->print(" ");
1375 gclog_or_tty->print("[%s :", str);
1376 for (uint i = 0; i < ParallelGCThreads; ++i) {
1377 double val = data[i];
1378 if (val < min)
1379 min = val;
1380 if (val > max)
1381 max = val;
1382 total += val;
1383 gclog_or_tty->print(" %d", (int) val);
1384 }
1385 if (summary) {
1386 gclog_or_tty->print_cr("");
1387 double avg = total / (double) ParallelGCThreads;
1388 gclog_or_tty->print(" ");
1389 for (j = 0; j < level; ++j)
1390 gclog_or_tty->print(" ");
1391 gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
1392 (int)total, (int)avg, (int)min, (int)max);
1393 }
1394 gclog_or_tty->print_cr("]");
1395 }
1397 void G1CollectorPolicy::print_stats (int level,
1398 const char* str,
1399 double value) {
1400 for (int j = 0; j < level; ++j)
1401 gclog_or_tty->print(" ");
1402 gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
1403 }
1405 void G1CollectorPolicy::print_stats (int level,
1406 const char* str,
1407 int value) {
1408 for (int j = 0; j < level; ++j)
1409 gclog_or_tty->print(" ");
1410 gclog_or_tty->print_cr("[%s: %d]", str, value);
1411 }
1413 double G1CollectorPolicy::avg_value (double* data) {
1414 if (ParallelGCThreads > 0) {
1415 double ret = 0.0;
1416 for (uint i = 0; i < ParallelGCThreads; ++i)
1417 ret += data[i];
1418 return ret / (double) ParallelGCThreads;
1419 } else {
1420 return data[0];
1421 }
1422 }
1424 double G1CollectorPolicy::max_value (double* data) {
1425 if (ParallelGCThreads > 0) {
1426 double ret = data[0];
1427 for (uint i = 1; i < ParallelGCThreads; ++i)
1428 if (data[i] > ret)
1429 ret = data[i];
1430 return ret;
1431 } else {
1432 return data[0];
1433 }
1434 }
1436 double G1CollectorPolicy::sum_of_values (double* data) {
1437 if (ParallelGCThreads > 0) {
1438 double sum = 0.0;
1439 for (uint i = 0; i < ParallelGCThreads; i++)
1440 sum += data[i];
1441 return sum;
1442 } else {
1443 return data[0];
1444 }
1445 }
1447 double G1CollectorPolicy::max_sum (double* data1,
1448 double* data2) {
1449 double ret = data1[0] + data2[0];
1451 if (ParallelGCThreads > 0) {
1452 for (uint i = 1; i < ParallelGCThreads; ++i) {
1453 double data = data1[i] + data2[i];
1454 if (data > ret)
1455 ret = data;
1456 }
1457 }
1458 return ret;
1459 }
1461 // Anything below that is considered to be zero
1462 #define MIN_TIMER_GRANULARITY 0.0000001
1464 void G1CollectorPolicy::record_collection_pause_end(bool popular,
1465 bool abandoned) {
1466 double end_time_sec = os::elapsedTime();
1467 double elapsed_ms = _last_pause_time_ms;
1468 bool parallel = ParallelGCThreads > 0;
1469 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1470 size_t rs_size =
1471 _cur_collection_pause_used_regions_at_start - collection_set_size();
1472 size_t cur_used_bytes = _g1->used();
1473 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1474 bool last_pause_included_initial_mark = false;
1476 #ifndef PRODUCT
1477 if (G1YoungSurvRateVerbose) {
1478 gclog_or_tty->print_cr("");
1479 _short_lived_surv_rate_group->print();
1480 // do that for any other surv rate groups too
1481 }
1482 #endif // PRODUCT
1484 checkpoint_conc_overhead();
1486 if (in_young_gc_mode()) {
1487 last_pause_included_initial_mark = _should_initiate_conc_mark;
1488 if (last_pause_included_initial_mark)
1489 record_concurrent_mark_init_end_pre(0.0);
1491 size_t min_used_targ =
1492 (_g1->capacity() / 100) * (G1SteadyStateUsed - G1SteadyStateUsedDelta);
1494 if (cur_used_bytes > min_used_targ) {
1495 if (cur_used_bytes <= _prev_collection_pause_used_at_end_bytes) {
1496 } else if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1497 _should_initiate_conc_mark = true;
1498 }
1499 }
1501 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1502 }
1504 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1505 end_time_sec, false);
1507 guarantee(_cur_collection_pause_used_regions_at_start >=
1508 collection_set_size(),
1509 "Negative RS size?");
1511 // This assert is exempted when we're doing parallel collection pauses,
1512 // because the fragmentation caused by the parallel GC allocation buffers
1513 // can lead to more memory being used during collection than was used
1514 // before. Best leave this out until the fragmentation problem is fixed.
1515 // Pauses in which evacuation failed can also lead to negative
1516 // collections, since no space is reclaimed from a region containing an
1517 // object whose evacuation failed.
1518 // Further, we're now always doing parallel collection. But I'm still
1519 // leaving this here as a placeholder for a more precise assertion later.
1520 // (DLD, 10/05.)
1521 assert((true || parallel) // Always using GC LABs now.
1522 || _g1->evacuation_failed()
1523 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1524 "Negative collection");
1526 size_t freed_bytes =
1527 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1528 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1529 double survival_fraction =
1530 (double)surviving_bytes/
1531 (double)_collection_set_bytes_used_before;
1533 _n_pauses++;
1535 if (!abandoned) {
1536 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1537 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1538 _recent_evac_times_ms->add(evac_ms);
1539 _recent_pause_times_ms->add(elapsed_ms);
1541 _recent_rs_sizes->add(rs_size);
1543 // We exempt parallel collection from this check because Alloc Buffer
1544 // fragmentation can produce negative collections. Same with evac
1545 // failure.
1546 // Further, we're now always doing parallel collection. But I'm still
1547 // leaving this here as a placeholder for a more precise assertion later.
1548 // (DLD, 10/05.
1549 assert((true || parallel)
1550 || _g1->evacuation_failed()
1551 || surviving_bytes <= _collection_set_bytes_used_before,
1552 "Or else negative collection!");
1553 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1554 _recent_CS_bytes_surviving->add(surviving_bytes);
1556 // this is where we update the allocation rate of the application
1557 double app_time_ms =
1558 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1559 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1560 // This usually happens due to the timer not having the required
1561 // granularity. Some Linuxes are the usual culprits.
1562 // We'll just set it to something (arbitrarily) small.
1563 app_time_ms = 1.0;
1564 }
1565 size_t regions_allocated =
1566 (_region_num_young - _prev_region_num_young) +
1567 (_region_num_tenured - _prev_region_num_tenured);
1568 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1569 _alloc_rate_ms_seq->add(alloc_rate_ms);
1570 _prev_region_num_young = _region_num_young;
1571 _prev_region_num_tenured = _region_num_tenured;
1573 double interval_ms =
1574 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1575 update_recent_gc_times(end_time_sec, elapsed_ms);
1576 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1577 assert(recent_avg_pause_time_ratio() < 1.00, "All GC?");
1578 }
1580 if (G1PolicyVerbose > 1) {
1581 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1582 }
1584 PauseSummary* summary;
1585 if (!abandoned && !popular)
1586 summary = _non_pop_summary;
1587 else if (!abandoned && popular)
1588 summary = _pop_summary;
1589 else if (abandoned && !popular)
1590 summary = _non_pop_abandoned_summary;
1591 else if (abandoned && popular)
1592 summary = _pop_abandoned_summary;
1593 else
1594 guarantee(false, "should not get here!");
1596 double pop_update_rs_time;
1597 double pop_update_rs_processed_buffers;
1598 double pop_scan_rs_time;
1599 double pop_closure_app_time;
1600 double pop_other_time;
1602 if (popular) {
1603 PopPreambleSummary* preamble_summary = summary->pop_preamble_summary();
1604 guarantee(preamble_summary != NULL, "should not be null!");
1606 pop_update_rs_time = avg_value(_pop_par_last_update_rs_times_ms);
1607 pop_update_rs_processed_buffers =
1608 sum_of_values(_pop_par_last_update_rs_processed_buffers);
1609 pop_scan_rs_time = avg_value(_pop_par_last_scan_rs_times_ms);
1610 pop_closure_app_time = avg_value(_pop_par_last_closure_app_times_ms);
1611 pop_other_time = _cur_popular_preamble_time_ms -
1612 (pop_update_rs_time + pop_scan_rs_time + pop_closure_app_time +
1613 _cur_popular_evac_time_ms);
1615 preamble_summary->record_pop_preamble_time_ms(_cur_popular_preamble_time_ms);
1616 preamble_summary->record_pop_update_rs_time_ms(pop_update_rs_time);
1617 preamble_summary->record_pop_scan_rs_time_ms(pop_scan_rs_time);
1618 preamble_summary->record_pop_closure_app_time_ms(pop_closure_app_time);
1619 preamble_summary->record_pop_evacuation_time_ms(_cur_popular_evac_time_ms);
1620 preamble_summary->record_pop_other_time_ms(pop_other_time);
1621 }
1623 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1624 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1625 double scan_only_time = avg_value(_par_last_scan_only_times_ms);
1626 double scan_only_regions_scanned =
1627 sum_of_values(_par_last_scan_only_regions_scanned);
1628 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1629 double update_rs_processed_buffers =
1630 sum_of_values(_par_last_update_rs_processed_buffers);
1631 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1632 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1633 double termination_time = avg_value(_par_last_termination_times_ms);
1635 double parallel_other_time;
1636 if (!abandoned) {
1637 MainBodySummary* body_summary = summary->main_body_summary();
1638 guarantee(body_summary != NULL, "should not be null!");
1640 if (_satb_drain_time_set)
1641 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1642 else
1643 body_summary->record_satb_drain_time_ms(0.0);
1644 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1645 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1646 body_summary->record_scan_only_time_ms(scan_only_time);
1647 body_summary->record_update_rs_time_ms(update_rs_time);
1648 body_summary->record_scan_rs_time_ms(scan_rs_time);
1649 body_summary->record_obj_copy_time_ms(obj_copy_time);
1650 if (parallel) {
1651 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1652 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1653 body_summary->record_termination_time_ms(termination_time);
1654 parallel_other_time = _cur_collection_par_time_ms -
1655 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1656 scan_only_time + scan_rs_time + obj_copy_time + termination_time);
1657 body_summary->record_parallel_other_time_ms(parallel_other_time);
1658 }
1659 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1660 }
1662 if (G1PolicyVerbose > 1) {
1663 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1664 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1665 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1666 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1667 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1668 " |RS|: " SIZE_FORMAT,
1669 elapsed_ms, recent_avg_time_for_pauses_ms(),
1670 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1671 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1672 evac_ms, recent_avg_time_for_evac_ms(),
1673 scan_rs_time,
1674 recent_avg_time_for_pauses_ms() -
1675 recent_avg_time_for_G1_strong_ms(),
1676 rs_size);
1678 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1679 " At end " SIZE_FORMAT "K\n"
1680 " garbage : " SIZE_FORMAT "K"
1681 " of " SIZE_FORMAT "K\n"
1682 " survival : %6.2f%% (%6.2f%% avg)",
1683 _cur_collection_pause_used_at_start_bytes/K,
1684 _g1->used()/K, freed_bytes/K,
1685 _collection_set_bytes_used_before/K,
1686 survival_fraction*100.0,
1687 recent_avg_survival_fraction()*100.0);
1688 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1689 recent_avg_pause_time_ratio() * 100.0);
1690 }
1692 double other_time_ms = elapsed_ms;
1693 if (popular)
1694 other_time_ms -= _cur_popular_preamble_time_ms;
1696 if (!abandoned) {
1697 if (_satb_drain_time_set)
1698 other_time_ms -= _cur_satb_drain_time_ms;
1700 if (parallel)
1701 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1702 else
1703 other_time_ms -=
1704 update_rs_time +
1705 ext_root_scan_time + mark_stack_scan_time + scan_only_time +
1706 scan_rs_time + obj_copy_time;
1707 }
1709 if (PrintGCDetails) {
1710 gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
1711 (popular && !abandoned) ? " (popular)" :
1712 (!popular && abandoned) ? " (abandoned)" :
1713 (popular && abandoned) ? " (popular/abandoned)" : "",
1714 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1715 elapsed_ms / 1000.0);
1717 if (!abandoned) {
1718 if (_satb_drain_time_set)
1719 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1720 if (_last_satb_drain_processed_buffers >= 0)
1721 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1722 }
1723 if (popular)
1724 print_stats(1, "Popularity Preamble", _cur_popular_preamble_time_ms);
1725 if (parallel) {
1726 if (popular) {
1727 print_par_stats(2, "Update RS (Start)", _pop_par_last_update_rs_start_times_ms, false);
1728 print_par_stats(2, "Update RS", _pop_par_last_update_rs_times_ms);
1729 if (G1RSBarrierUseQueue)
1730 print_par_buffers(3, "Processed Buffers",
1731 _pop_par_last_update_rs_processed_buffers, true);
1732 print_par_stats(2, "Scan RS", _pop_par_last_scan_rs_times_ms);
1733 print_par_stats(2, "Closure app", _pop_par_last_closure_app_times_ms);
1734 print_stats(2, "Evacuation", _cur_popular_evac_time_ms);
1735 print_stats(2, "Other", pop_other_time);
1736 }
1737 if (!abandoned) {
1738 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1739 if (!popular) {
1740 print_par_stats(2, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);
1741 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1742 if (G1RSBarrierUseQueue)
1743 print_par_buffers(3, "Processed Buffers",
1744 _par_last_update_rs_processed_buffers, true);
1745 }
1746 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1747 print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
1748 print_par_stats(2, "Scan-Only Scanning", _par_last_scan_only_times_ms);
1749 print_par_buffers(3, "Scan-Only Regions",
1750 _par_last_scan_only_regions_scanned, true);
1751 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1752 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1753 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1754 print_stats(2, "Other", parallel_other_time);
1755 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1756 }
1757 } else {
1758 if (popular) {
1759 print_stats(2, "Update RS", pop_update_rs_time);
1760 if (G1RSBarrierUseQueue)
1761 print_stats(3, "Processed Buffers",
1762 (int)pop_update_rs_processed_buffers);
1763 print_stats(2, "Scan RS", pop_scan_rs_time);
1764 print_stats(2, "Closure App", pop_closure_app_time);
1765 print_stats(2, "Evacuation", _cur_popular_evac_time_ms);
1766 print_stats(2, "Other", pop_other_time);
1767 }
1768 if (!abandoned) {
1769 if (!popular) {
1770 print_stats(1, "Update RS", update_rs_time);
1771 if (G1RSBarrierUseQueue)
1772 print_stats(2, "Processed Buffers",
1773 (int)update_rs_processed_buffers);
1774 }
1775 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1776 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1777 print_stats(1, "Scan-Only Scanning", scan_only_time);
1778 print_stats(1, "Scan RS", scan_rs_time);
1779 print_stats(1, "Object Copying", obj_copy_time);
1780 }
1781 }
1782 print_stats(1, "Other", other_time_ms);
1783 for (int i = 0; i < _aux_num; ++i) {
1784 if (_cur_aux_times_set[i]) {
1785 char buffer[96];
1786 sprintf(buffer, "Aux%d", i);
1787 print_stats(1, buffer, _cur_aux_times_ms[i]);
1788 }
1789 }
1790 }
1791 if (PrintGCDetails)
1792 gclog_or_tty->print(" [");
1793 if (PrintGC || PrintGCDetails)
1794 _g1->print_size_transition(gclog_or_tty,
1795 _cur_collection_pause_used_at_start_bytes,
1796 _g1->used(), _g1->capacity());
1797 if (PrintGCDetails)
1798 gclog_or_tty->print_cr("]");
1800 _all_pause_times_ms->add(elapsed_ms);
1801 summary->record_total_time_ms(elapsed_ms);
1802 summary->record_other_time_ms(other_time_ms);
1803 for (int i = 0; i < _aux_num; ++i)
1804 if (_cur_aux_times_set[i])
1805 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1807 // Reset marks-between-pauses counter.
1808 _n_marks_since_last_pause = 0;
1810 // Update the efficiency-since-mark vars.
1811 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1812 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1813 // This usually happens due to the timer not having the required
1814 // granularity. Some Linuxes are the usual culprits.
1815 // We'll just set it to something (arbitrarily) small.
1816 proc_ms = 1.0;
1817 }
1818 double cur_efficiency = (double) freed_bytes / proc_ms;
1820 bool new_in_marking_window = _in_marking_window;
1821 bool new_in_marking_window_im = false;
1822 if (_should_initiate_conc_mark) {
1823 new_in_marking_window = true;
1824 new_in_marking_window_im = true;
1825 }
1827 if (in_young_gc_mode()) {
1828 if (_last_full_young_gc) {
1829 set_full_young_gcs(false);
1830 _last_full_young_gc = false;
1831 }
1833 if ( !_last_young_gc_full ) {
1834 if ( _should_revert_to_full_young_gcs ||
1835 _known_garbage_ratio < 0.05 ||
1836 (adaptive_young_list_length() &&
1837 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1838 set_full_young_gcs(true);
1839 }
1840 }
1841 _should_revert_to_full_young_gcs = false;
1843 if (_last_young_gc_full && !_during_marking)
1844 _young_gc_eff_seq->add(cur_efficiency);
1845 }
1847 _short_lived_surv_rate_group->start_adding_regions();
1848 // do that for any other surv rate groupsx
1850 // <NEW PREDICTION>
1852 if (!popular && !abandoned) {
1853 double pause_time_ms = elapsed_ms;
1855 size_t diff = 0;
1856 if (_max_pending_cards >= _pending_cards)
1857 diff = _max_pending_cards - _pending_cards;
1858 _pending_card_diff_seq->add((double) diff);
1860 double cost_per_card_ms = 0.0;
1861 if (_pending_cards > 0) {
1862 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1863 _cost_per_card_ms_seq->add(cost_per_card_ms);
1864 }
1866 double cost_per_scan_only_region_ms = 0.0;
1867 if (scan_only_regions_scanned > 0.0) {
1868 cost_per_scan_only_region_ms =
1869 scan_only_time / scan_only_regions_scanned;
1870 if (_in_marking_window_im)
1871 _cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);
1872 else
1873 _cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_ms);
1874 }
1876 size_t cards_scanned = _g1->cards_scanned();
1878 double cost_per_entry_ms = 0.0;
1879 if (cards_scanned > 10) {
1880 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1881 if (_last_young_gc_full)
1882 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1883 else
1884 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1885 }
1887 if (_max_rs_lengths > 0) {
1888 double cards_per_entry_ratio =
1889 (double) cards_scanned / (double) _max_rs_lengths;
1890 if (_last_young_gc_full)
1891 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1892 else
1893 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1894 }
1896 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1897 if (rs_length_diff >= 0)
1898 _rs_length_diff_seq->add((double) rs_length_diff);
1900 size_t copied_bytes = surviving_bytes;
1901 double cost_per_byte_ms = 0.0;
1902 if (copied_bytes > 0) {
1903 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1904 if (_in_marking_window)
1905 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1906 else
1907 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1908 }
1910 double all_other_time_ms = pause_time_ms -
1911 (update_rs_time + scan_only_time + scan_rs_time + obj_copy_time +
1912 _mark_closure_time_ms + termination_time);
1914 double young_other_time_ms = 0.0;
1915 if (_recorded_young_regions > 0) {
1916 young_other_time_ms =
1917 _recorded_young_cset_choice_time_ms +
1918 _recorded_young_free_cset_time_ms;
1919 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1920 (double) _recorded_young_regions);
1921 }
1922 double non_young_other_time_ms = 0.0;
1923 if (_recorded_non_young_regions > 0) {
1924 non_young_other_time_ms =
1925 _recorded_non_young_cset_choice_time_ms +
1926 _recorded_non_young_free_cset_time_ms;
1928 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1929 (double) _recorded_non_young_regions);
1930 }
1932 double constant_other_time_ms = all_other_time_ms -
1933 (young_other_time_ms + non_young_other_time_ms);
1934 _constant_other_time_ms_seq->add(constant_other_time_ms);
1936 double survival_ratio = 0.0;
1937 if (_bytes_in_collection_set_before_gc > 0) {
1938 survival_ratio = (double) bytes_in_to_space_during_gc() /
1939 (double) _bytes_in_collection_set_before_gc;
1940 }
1942 _pending_cards_seq->add((double) _pending_cards);
1943 _scanned_cards_seq->add((double) cards_scanned);
1944 _rs_lengths_seq->add((double) _max_rs_lengths);
1946 double expensive_region_limit_ms =
1947 (double) G1MaxPauseTimeMS - predict_constant_other_time_ms();
1948 if (expensive_region_limit_ms < 0.0) {
1949 // this means that the other time was predicted to be longer than
1950 // than the max pause time
1951 expensive_region_limit_ms = (double) G1MaxPauseTimeMS;
1952 }
1953 _expensive_region_limit_ms = expensive_region_limit_ms;
1955 if (PREDICTIONS_VERBOSE) {
1956 gclog_or_tty->print_cr("");
1957 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1958 "REGIONS %d %d %d %d "
1959 "PENDING_CARDS %d %d "
1960 "CARDS_SCANNED %d %d "
1961 "RS_LENGTHS %d %d "
1962 "SCAN_ONLY_SCAN %1.6lf %1.6lf "
1963 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1964 "SURVIVAL_RATIO %1.6lf %1.6lf "
1965 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1966 "OTHER_YOUNG %1.6lf %1.6lf "
1967 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1968 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1969 "ELAPSED %1.6lf %1.6lf ",
1970 _cur_collection_start_sec,
1971 (!_last_young_gc_full) ? 2 :
1972 (last_pause_included_initial_mark) ? 1 : 0,
1973 _recorded_region_num,
1974 _recorded_young_regions,
1975 _recorded_scan_only_regions,
1976 _recorded_non_young_regions,
1977 _predicted_pending_cards, _pending_cards,
1978 _predicted_cards_scanned, cards_scanned,
1979 _predicted_rs_lengths, _max_rs_lengths,
1980 _predicted_scan_only_scan_time_ms, scan_only_time,
1981 _predicted_rs_update_time_ms, update_rs_time,
1982 _predicted_rs_scan_time_ms, scan_rs_time,
1983 _predicted_survival_ratio, survival_ratio,
1984 _predicted_object_copy_time_ms, obj_copy_time,
1985 _predicted_constant_other_time_ms, constant_other_time_ms,
1986 _predicted_young_other_time_ms, young_other_time_ms,
1987 _predicted_non_young_other_time_ms,
1988 non_young_other_time_ms,
1989 _vtime_diff_ms, termination_time,
1990 _predicted_pause_time_ms, elapsed_ms);
1991 }
1993 if (G1PolicyVerbose > 0) {
1994 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1995 _predicted_pause_time_ms,
1996 (_within_target) ? "within" : "outside",
1997 elapsed_ms);
1998 }
2000 }
2002 _in_marking_window = new_in_marking_window;
2003 _in_marking_window_im = new_in_marking_window_im;
2004 _free_regions_at_end_of_collection = _g1->free_regions();
2005 _scan_only_regions_at_end_of_collection = _g1->young_list_length();
2006 calculate_young_list_min_length();
2007 calculate_young_list_target_config();
2009 // </NEW PREDICTION>
2011 _target_pause_time_ms = -1.0;
2012 }
2014 // <NEW PREDICTION>
2016 double
2017 G1CollectorPolicy::
2018 predict_young_collection_elapsed_time_ms(size_t adjustment) {
2019 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
2021 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2022 size_t young_num = g1h->young_list_length();
2023 if (young_num == 0)
2024 return 0.0;
2026 young_num += adjustment;
2027 size_t pending_cards = predict_pending_cards();
2028 size_t rs_lengths = g1h->young_list_sampled_rs_lengths() +
2029 predict_rs_length_diff();
2030 size_t card_num;
2031 if (full_young_gcs())
2032 card_num = predict_young_card_num(rs_lengths);
2033 else
2034 card_num = predict_non_young_card_num(rs_lengths);
2035 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
2036 double accum_yg_surv_rate =
2037 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
2039 size_t bytes_to_copy =
2040 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
2042 return
2043 predict_rs_update_time_ms(pending_cards) +
2044 predict_rs_scan_time_ms(card_num) +
2045 predict_object_copy_time_ms(bytes_to_copy) +
2046 predict_young_other_time_ms(young_num) +
2047 predict_constant_other_time_ms();
2048 }
2050 double
2051 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
2052 size_t rs_length = predict_rs_length_diff();
2053 size_t card_num;
2054 if (full_young_gcs())
2055 card_num = predict_young_card_num(rs_length);
2056 else
2057 card_num = predict_non_young_card_num(rs_length);
2058 return predict_base_elapsed_time_ms(pending_cards, card_num);
2059 }
2061 double
2062 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
2063 size_t scanned_cards) {
2064 return
2065 predict_rs_update_time_ms(pending_cards) +
2066 predict_rs_scan_time_ms(scanned_cards) +
2067 predict_constant_other_time_ms();
2068 }
2070 double
2071 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
2072 bool young) {
2073 size_t rs_length = hr->rem_set()->occupied();
2074 size_t card_num;
2075 if (full_young_gcs())
2076 card_num = predict_young_card_num(rs_length);
2077 else
2078 card_num = predict_non_young_card_num(rs_length);
2079 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2081 double region_elapsed_time_ms =
2082 predict_rs_scan_time_ms(card_num) +
2083 predict_object_copy_time_ms(bytes_to_copy);
2085 if (young)
2086 region_elapsed_time_ms += predict_young_other_time_ms(1);
2087 else
2088 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
2090 return region_elapsed_time_ms;
2091 }
2093 size_t
2094 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
2095 size_t bytes_to_copy;
2096 if (hr->is_marked())
2097 bytes_to_copy = hr->max_live_bytes();
2098 else {
2099 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
2100 "invariant" );
2101 int age = hr->age_in_surv_rate_group();
2102 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
2103 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
2104 }
2106 return bytes_to_copy;
2107 }
2109 void
2110 G1CollectorPolicy::start_recording_regions() {
2111 _recorded_rs_lengths = 0;
2112 _recorded_scan_only_regions = 0;
2113 _recorded_young_regions = 0;
2114 _recorded_non_young_regions = 0;
2116 #if PREDICTIONS_VERBOSE
2117 _predicted_rs_lengths = 0;
2118 _predicted_cards_scanned = 0;
2120 _recorded_marked_bytes = 0;
2121 _recorded_young_bytes = 0;
2122 _predicted_bytes_to_copy = 0;
2123 #endif // PREDICTIONS_VERBOSE
2124 }
2126 void
2127 G1CollectorPolicy::record_cset_region(HeapRegion* hr, bool young) {
2128 if (young) {
2129 ++_recorded_young_regions;
2130 } else {
2131 ++_recorded_non_young_regions;
2132 }
2133 #if PREDICTIONS_VERBOSE
2134 if (young) {
2135 _recorded_young_bytes += hr->used();
2136 } else {
2137 _recorded_marked_bytes += hr->max_live_bytes();
2138 }
2139 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
2140 #endif // PREDICTIONS_VERBOSE
2142 size_t rs_length = hr->rem_set()->occupied();
2143 _recorded_rs_lengths += rs_length;
2144 }
2146 void
2147 G1CollectorPolicy::record_scan_only_regions(size_t scan_only_length) {
2148 _recorded_scan_only_regions = scan_only_length;
2149 }
2151 void
2152 G1CollectorPolicy::end_recording_regions() {
2153 #if PREDICTIONS_VERBOSE
2154 _predicted_pending_cards = predict_pending_cards();
2155 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
2156 if (full_young_gcs())
2157 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
2158 else
2159 _predicted_cards_scanned +=
2160 predict_non_young_card_num(_predicted_rs_lengths);
2161 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
2163 _predicted_scan_only_scan_time_ms =
2164 predict_scan_only_time_ms(_recorded_scan_only_regions);
2165 _predicted_rs_update_time_ms =
2166 predict_rs_update_time_ms(_g1->pending_card_num());
2167 _predicted_rs_scan_time_ms =
2168 predict_rs_scan_time_ms(_predicted_cards_scanned);
2169 _predicted_object_copy_time_ms =
2170 predict_object_copy_time_ms(_predicted_bytes_to_copy);
2171 _predicted_constant_other_time_ms =
2172 predict_constant_other_time_ms();
2173 _predicted_young_other_time_ms =
2174 predict_young_other_time_ms(_recorded_young_regions);
2175 _predicted_non_young_other_time_ms =
2176 predict_non_young_other_time_ms(_recorded_non_young_regions);
2178 _predicted_pause_time_ms =
2179 _predicted_scan_only_scan_time_ms +
2180 _predicted_rs_update_time_ms +
2181 _predicted_rs_scan_time_ms +
2182 _predicted_object_copy_time_ms +
2183 _predicted_constant_other_time_ms +
2184 _predicted_young_other_time_ms +
2185 _predicted_non_young_other_time_ms;
2186 #endif // PREDICTIONS_VERBOSE
2187 }
2189 void G1CollectorPolicy::check_if_region_is_too_expensive(double
2190 predicted_time_ms) {
2191 // I don't think we need to do this when in young GC mode since
2192 // marking will be initiated next time we hit the soft limit anyway...
2193 if (predicted_time_ms > _expensive_region_limit_ms) {
2194 if (!in_young_gc_mode()) {
2195 set_full_young_gcs(true);
2196 _should_initiate_conc_mark = true;
2197 } else
2198 // no point in doing another partial one
2199 _should_revert_to_full_young_gcs = true;
2200 }
2201 }
2203 // </NEW PREDICTION>
2206 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
2207 double elapsed_ms) {
2208 _recent_gc_times_ms->add(elapsed_ms);
2209 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
2210 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
2211 }
2213 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
2214 if (_recent_pause_times_ms->num() == 0) return (double) G1MaxPauseTimeMS;
2215 else return _recent_pause_times_ms->avg();
2216 }
2218 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
2219 if (_recent_CH_strong_roots_times_ms->num() == 0)
2220 return (double)G1MaxPauseTimeMS/3.0;
2221 else return _recent_CH_strong_roots_times_ms->avg();
2222 }
2224 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
2225 if (_recent_G1_strong_roots_times_ms->num() == 0)
2226 return (double)G1MaxPauseTimeMS/3.0;
2227 else return _recent_G1_strong_roots_times_ms->avg();
2228 }
2230 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
2231 if (_recent_evac_times_ms->num() == 0) return (double)G1MaxPauseTimeMS/3.0;
2232 else return _recent_evac_times_ms->avg();
2233 }
2235 int G1CollectorPolicy::number_of_recent_gcs() {
2236 assert(_recent_CH_strong_roots_times_ms->num() ==
2237 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
2238 assert(_recent_G1_strong_roots_times_ms->num() ==
2239 _recent_evac_times_ms->num(), "Sequence out of sync");
2240 assert(_recent_evac_times_ms->num() ==
2241 _recent_pause_times_ms->num(), "Sequence out of sync");
2242 assert(_recent_pause_times_ms->num() ==
2243 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
2244 assert(_recent_CS_bytes_used_before->num() ==
2245 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
2246 return _recent_pause_times_ms->num();
2247 }
2249 double G1CollectorPolicy::recent_avg_survival_fraction() {
2250 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
2251 _recent_CS_bytes_used_before);
2252 }
2254 double G1CollectorPolicy::last_survival_fraction() {
2255 return last_survival_fraction_work(_recent_CS_bytes_surviving,
2256 _recent_CS_bytes_used_before);
2257 }
2259 double
2260 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
2261 TruncatedSeq* before) {
2262 assert(surviving->num() == before->num(), "Sequence out of sync");
2263 if (before->sum() > 0.0) {
2264 double recent_survival_rate = surviving->sum() / before->sum();
2265 // We exempt parallel collection from this check because Alloc Buffer
2266 // fragmentation can produce negative collections.
2267 // Further, we're now always doing parallel collection. But I'm still
2268 // leaving this here as a placeholder for a more precise assertion later.
2269 // (DLD, 10/05.)
2270 assert((true || ParallelGCThreads > 0) ||
2271 _g1->evacuation_failed() ||
2272 recent_survival_rate <= 1.0, "Or bad frac");
2273 return recent_survival_rate;
2274 } else {
2275 return 1.0; // Be conservative.
2276 }
2277 }
2279 double
2280 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
2281 TruncatedSeq* before) {
2282 assert(surviving->num() == before->num(), "Sequence out of sync");
2283 if (surviving->num() > 0 && before->last() > 0.0) {
2284 double last_survival_rate = surviving->last() / before->last();
2285 // We exempt parallel collection from this check because Alloc Buffer
2286 // fragmentation can produce negative collections.
2287 // Further, we're now always doing parallel collection. But I'm still
2288 // leaving this here as a placeholder for a more precise assertion later.
2289 // (DLD, 10/05.)
2290 assert((true || ParallelGCThreads > 0) ||
2291 last_survival_rate <= 1.0, "Or bad frac");
2292 return last_survival_rate;
2293 } else {
2294 return 1.0;
2295 }
2296 }
2298 static const int survival_min_obs = 5;
2299 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
2300 static const double min_survival_rate = 0.1;
2302 double
2303 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
2304 double latest) {
2305 double res = avg;
2306 if (number_of_recent_gcs() < survival_min_obs) {
2307 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
2308 }
2309 res = MAX2(res, latest);
2310 res = MAX2(res, min_survival_rate);
2311 // In the parallel case, LAB fragmentation can produce "negative
2312 // collections"; so can evac failure. Cap at 1.0
2313 res = MIN2(res, 1.0);
2314 return res;
2315 }
2317 size_t G1CollectorPolicy::expansion_amount() {
2318 if ((int)(recent_avg_pause_time_ratio() * 100.0) > G1GCPct) {
2319 // We will double the existing space, or take G1ExpandByPctOfAvail % of
2320 // the available expansion space, whichever is smaller, bounded below
2321 // by a minimum expansion (unless that's all that's left.)
2322 const size_t min_expand_bytes = 1*M;
2323 size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
2324 size_t committed_bytes = _g1->capacity();
2325 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2326 size_t expand_bytes;
2327 size_t expand_bytes_via_pct =
2328 uncommitted_bytes * G1ExpandByPctOfAvail / 100;
2329 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2330 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2331 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2332 if (G1PolicyVerbose > 1) {
2333 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2334 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2335 " Answer = %d.\n",
2336 recent_avg_pause_time_ratio(),
2337 byte_size_in_proper_unit(committed_bytes),
2338 proper_unit_for_byte_size(committed_bytes),
2339 byte_size_in_proper_unit(uncommitted_bytes),
2340 proper_unit_for_byte_size(uncommitted_bytes),
2341 byte_size_in_proper_unit(expand_bytes_via_pct),
2342 proper_unit_for_byte_size(expand_bytes_via_pct),
2343 byte_size_in_proper_unit(expand_bytes),
2344 proper_unit_for_byte_size(expand_bytes));
2345 }
2346 return expand_bytes;
2347 } else {
2348 return 0;
2349 }
2350 }
2352 void G1CollectorPolicy::note_start_of_mark_thread() {
2353 _mark_thread_startup_sec = os::elapsedTime();
2354 }
2356 class CountCSClosure: public HeapRegionClosure {
2357 G1CollectorPolicy* _g1_policy;
2358 public:
2359 CountCSClosure(G1CollectorPolicy* g1_policy) :
2360 _g1_policy(g1_policy) {}
2361 bool doHeapRegion(HeapRegion* r) {
2362 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2363 return false;
2364 }
2365 };
2367 void G1CollectorPolicy::count_CS_bytes_used() {
2368 CountCSClosure cs_closure(this);
2369 _g1->collection_set_iterate(&cs_closure);
2370 }
2372 static void print_indent(int level) {
2373 for (int j = 0; j < level+1; ++j)
2374 gclog_or_tty->print(" ");
2375 }
2377 void G1CollectorPolicy::print_summary (int level,
2378 const char* str,
2379 NumberSeq* seq) const {
2380 double sum = seq->sum();
2381 print_indent(level);
2382 gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2383 str, sum / 1000.0, seq->avg());
2384 }
2386 void G1CollectorPolicy::print_summary_sd (int level,
2387 const char* str,
2388 NumberSeq* seq) const {
2389 print_summary(level, str, seq);
2390 print_indent(level + 5);
2391 gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2392 seq->num(), seq->sd(), seq->maximum());
2393 }
2395 void G1CollectorPolicy::check_other_times(int level,
2396 NumberSeq* other_times_ms,
2397 NumberSeq* calc_other_times_ms) const {
2398 bool should_print = false;
2400 double max_sum = MAX2(fabs(other_times_ms->sum()),
2401 fabs(calc_other_times_ms->sum()));
2402 double min_sum = MIN2(fabs(other_times_ms->sum()),
2403 fabs(calc_other_times_ms->sum()));
2404 double sum_ratio = max_sum / min_sum;
2405 if (sum_ratio > 1.1) {
2406 should_print = true;
2407 print_indent(level + 1);
2408 gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2409 }
2411 double max_avg = MAX2(fabs(other_times_ms->avg()),
2412 fabs(calc_other_times_ms->avg()));
2413 double min_avg = MIN2(fabs(other_times_ms->avg()),
2414 fabs(calc_other_times_ms->avg()));
2415 double avg_ratio = max_avg / min_avg;
2416 if (avg_ratio > 1.1) {
2417 should_print = true;
2418 print_indent(level + 1);
2419 gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2420 }
2422 if (other_times_ms->sum() < -0.01) {
2423 print_indent(level + 1);
2424 gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2425 }
2427 if (other_times_ms->avg() < -0.01) {
2428 print_indent(level + 1);
2429 gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2430 }
2432 if (calc_other_times_ms->sum() < -0.01) {
2433 should_print = true;
2434 print_indent(level + 1);
2435 gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2436 }
2438 if (calc_other_times_ms->avg() < -0.01) {
2439 should_print = true;
2440 print_indent(level + 1);
2441 gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2442 }
2444 if (should_print)
2445 print_summary(level, "Other(Calc)", calc_other_times_ms);
2446 }
2448 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2449 bool parallel = ParallelGCThreads > 0;
2450 MainBodySummary* body_summary = summary->main_body_summary();
2451 PopPreambleSummary* preamble_summary = summary->pop_preamble_summary();
2453 if (summary->get_total_seq()->num() > 0) {
2454 print_summary_sd(0,
2455 (preamble_summary == NULL) ? "Non-Popular Pauses" :
2456 "Popular Pauses",
2457 summary->get_total_seq());
2458 if (preamble_summary != NULL) {
2459 print_summary(1, "Popularity Preamble",
2460 preamble_summary->get_pop_preamble_seq());
2461 print_summary(2, "Update RS", preamble_summary->get_pop_update_rs_seq());
2462 print_summary(2, "Scan RS", preamble_summary->get_pop_scan_rs_seq());
2463 print_summary(2, "Closure App",
2464 preamble_summary->get_pop_closure_app_seq());
2465 print_summary(2, "Evacuation",
2466 preamble_summary->get_pop_evacuation_seq());
2467 print_summary(2, "Other", preamble_summary->get_pop_other_seq());
2468 {
2469 NumberSeq* other_parts[] = {
2470 preamble_summary->get_pop_update_rs_seq(),
2471 preamble_summary->get_pop_scan_rs_seq(),
2472 preamble_summary->get_pop_closure_app_seq(),
2473 preamble_summary->get_pop_evacuation_seq()
2474 };
2475 NumberSeq calc_other_times_ms(preamble_summary->get_pop_preamble_seq(),
2476 4, other_parts);
2477 check_other_times(2, preamble_summary->get_pop_other_seq(),
2478 &calc_other_times_ms);
2479 }
2480 }
2481 if (body_summary != NULL) {
2482 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2483 if (parallel) {
2484 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2485 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2486 print_summary(2, "Ext Root Scanning",
2487 body_summary->get_ext_root_scan_seq());
2488 print_summary(2, "Mark Stack Scanning",
2489 body_summary->get_mark_stack_scan_seq());
2490 print_summary(2, "Scan-Only Scanning",
2491 body_summary->get_scan_only_seq());
2492 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2493 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2494 print_summary(2, "Termination", body_summary->get_termination_seq());
2495 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2496 {
2497 NumberSeq* other_parts[] = {
2498 body_summary->get_update_rs_seq(),
2499 body_summary->get_ext_root_scan_seq(),
2500 body_summary->get_mark_stack_scan_seq(),
2501 body_summary->get_scan_only_seq(),
2502 body_summary->get_scan_rs_seq(),
2503 body_summary->get_obj_copy_seq(),
2504 body_summary->get_termination_seq()
2505 };
2506 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2507 7, other_parts);
2508 check_other_times(2, body_summary->get_parallel_other_seq(),
2509 &calc_other_times_ms);
2510 }
2511 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2512 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2513 } else {
2514 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2515 print_summary(1, "Ext Root Scanning",
2516 body_summary->get_ext_root_scan_seq());
2517 print_summary(1, "Mark Stack Scanning",
2518 body_summary->get_mark_stack_scan_seq());
2519 print_summary(1, "Scan-Only Scanning",
2520 body_summary->get_scan_only_seq());
2521 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2522 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2523 }
2524 }
2525 print_summary(1, "Other", summary->get_other_seq());
2526 {
2527 NumberSeq calc_other_times_ms;
2528 if (body_summary != NULL) {
2529 // not abandoned
2530 if (parallel) {
2531 // parallel
2532 NumberSeq* other_parts[] = {
2533 body_summary->get_satb_drain_seq(),
2534 (preamble_summary == NULL) ? NULL :
2535 preamble_summary->get_pop_preamble_seq(),
2536 body_summary->get_parallel_seq(),
2537 body_summary->get_clear_ct_seq()
2538 };
2539 calc_other_times_ms = NumberSeq (summary->get_total_seq(),
2540 4, other_parts);
2541 } else {
2542 // serial
2543 NumberSeq* other_parts[] = {
2544 body_summary->get_satb_drain_seq(),
2545 (preamble_summary == NULL) ? NULL :
2546 preamble_summary->get_pop_preamble_seq(),
2547 body_summary->get_update_rs_seq(),
2548 body_summary->get_ext_root_scan_seq(),
2549 body_summary->get_mark_stack_scan_seq(),
2550 body_summary->get_scan_only_seq(),
2551 body_summary->get_scan_rs_seq(),
2552 body_summary->get_obj_copy_seq()
2553 };
2554 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2555 8, other_parts);
2556 }
2557 } else {
2558 // abandoned
2559 NumberSeq* other_parts[] = {
2560 (preamble_summary == NULL) ? NULL :
2561 preamble_summary->get_pop_preamble_seq()
2562 };
2563 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2564 1, other_parts);
2565 }
2566 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2567 }
2568 } else {
2569 print_indent(0);
2570 gclog_or_tty->print_cr("none");
2571 }
2572 gclog_or_tty->print_cr("");
2573 }
2575 void
2576 G1CollectorPolicy::print_abandoned_summary(PauseSummary* non_pop_summary,
2577 PauseSummary* pop_summary) const {
2578 bool printed = false;
2579 if (non_pop_summary->get_total_seq()->num() > 0) {
2580 printed = true;
2581 print_summary(non_pop_summary);
2582 }
2583 if (pop_summary->get_total_seq()->num() > 0) {
2584 printed = true;
2585 print_summary(pop_summary);
2586 }
2588 if (!printed) {
2589 print_indent(0);
2590 gclog_or_tty->print_cr("none");
2591 gclog_or_tty->print_cr("");
2592 }
2593 }
2595 void G1CollectorPolicy::print_tracing_info() const {
2596 if (TraceGen0Time) {
2597 gclog_or_tty->print_cr("ALL PAUSES");
2598 print_summary_sd(0, "Total", _all_pause_times_ms);
2599 gclog_or_tty->print_cr("");
2600 gclog_or_tty->print_cr("");
2601 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2602 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2603 gclog_or_tty->print_cr("");
2605 gclog_or_tty->print_cr("NON-POPULAR PAUSES");
2606 print_summary(_non_pop_summary);
2608 gclog_or_tty->print_cr("POPULAR PAUSES");
2609 print_summary(_pop_summary);
2611 gclog_or_tty->print_cr("ABANDONED PAUSES");
2612 print_abandoned_summary(_non_pop_abandoned_summary,
2613 _pop_abandoned_summary);
2615 gclog_or_tty->print_cr("MISC");
2616 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2617 print_summary_sd(0, "Yields", _all_yield_times_ms);
2618 for (int i = 0; i < _aux_num; ++i) {
2619 if (_all_aux_times_ms[i].num() > 0) {
2620 char buffer[96];
2621 sprintf(buffer, "Aux%d", i);
2622 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2623 }
2624 }
2626 size_t all_region_num = _region_num_young + _region_num_tenured;
2627 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2628 "Tenured %8d (%6.2lf%%)",
2629 all_region_num,
2630 _region_num_young,
2631 (double) _region_num_young / (double) all_region_num * 100.0,
2632 _region_num_tenured,
2633 (double) _region_num_tenured / (double) all_region_num * 100.0);
2635 if (!G1RSBarrierUseQueue) {
2636 gclog_or_tty->print_cr("Of %d times conc refinement was enabled, %d (%7.2f%%) "
2637 "did zero traversals.",
2638 _conc_refine_enabled, _conc_refine_zero_traversals,
2639 _conc_refine_enabled > 0 ?
2640 100.0 * (float)_conc_refine_zero_traversals/
2641 (float)_conc_refine_enabled : 0.0);
2642 gclog_or_tty->print_cr(" Max # of traversals = %d.",
2643 _conc_refine_max_traversals);
2644 gclog_or_tty->print_cr("");
2645 }
2646 }
2647 if (TraceGen1Time) {
2648 if (_all_full_gc_times_ms->num() > 0) {
2649 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2650 _all_full_gc_times_ms->num(),
2651 _all_full_gc_times_ms->sum() / 1000.0);
2652 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2653 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2654 _all_full_gc_times_ms->sd(),
2655 _all_full_gc_times_ms->maximum());
2656 }
2657 }
2658 }
2660 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2661 #ifndef PRODUCT
2662 _short_lived_surv_rate_group->print_surv_rate_summary();
2663 // add this call for any other surv rate groups
2664 #endif // PRODUCT
2665 }
2667 void G1CollectorPolicy::update_conc_refine_data() {
2668 unsigned traversals = _g1->concurrent_g1_refine()->disable();
2669 if (traversals == 0) _conc_refine_zero_traversals++;
2670 _conc_refine_max_traversals = MAX2(_conc_refine_max_traversals,
2671 (size_t)traversals);
2673 if (G1PolicyVerbose > 1)
2674 gclog_or_tty->print_cr("Did a CR traversal series: %d traversals.", traversals);
2675 double multiplier = 1.0;
2676 if (traversals == 0) {
2677 multiplier = 4.0;
2678 } else if (traversals > (size_t)G1ConcRefineTargTraversals) {
2679 multiplier = 1.0/1.5;
2680 } else if (traversals < (size_t)G1ConcRefineTargTraversals) {
2681 multiplier = 1.5;
2682 }
2683 if (G1PolicyVerbose > 1) {
2684 gclog_or_tty->print_cr(" Multiplier = %7.2f.", multiplier);
2685 gclog_or_tty->print(" Delta went from %d regions to ",
2686 _conc_refine_current_delta);
2687 }
2688 _conc_refine_current_delta =
2689 MIN2(_g1->n_regions(),
2690 (size_t)(_conc_refine_current_delta * multiplier));
2691 _conc_refine_current_delta =
2692 MAX2(_conc_refine_current_delta, (size_t)1);
2693 if (G1PolicyVerbose > 1) {
2694 gclog_or_tty->print_cr("%d regions.", _conc_refine_current_delta);
2695 }
2696 _conc_refine_enabled++;
2697 }
2699 void G1CollectorPolicy::set_single_region_collection_set(HeapRegion* hr) {
2700 assert(collection_set() == NULL, "Must be no current CS.");
2701 _collection_set_size = 0;
2702 _collection_set_bytes_used_before = 0;
2703 add_to_collection_set(hr);
2704 count_CS_bytes_used();
2705 }
2707 bool
2708 G1CollectorPolicy::should_add_next_region_to_young_list() {
2709 assert(in_young_gc_mode(), "should be in young GC mode");
2710 bool ret;
2711 size_t young_list_length = _g1->young_list_length();
2712 size_t young_list_max_length = _young_list_target_length;
2713 if (G1FixedEdenSize) {
2714 young_list_max_length -= _max_survivor_regions;
2715 }
2716 if (young_list_length < young_list_max_length) {
2717 ret = true;
2718 ++_region_num_young;
2719 } else {
2720 ret = false;
2721 ++_region_num_tenured;
2722 }
2724 return ret;
2725 }
2727 #ifndef PRODUCT
2728 // for debugging, bit of a hack...
2729 static char*
2730 region_num_to_mbs(int length) {
2731 static char buffer[64];
2732 double bytes = (double) (length * HeapRegion::GrainBytes);
2733 double mbs = bytes / (double) (1024 * 1024);
2734 sprintf(buffer, "%7.2lfMB", mbs);
2735 return buffer;
2736 }
2737 #endif // PRODUCT
2739 void
2740 G1CollectorPolicy::checkpoint_conc_overhead() {
2741 double conc_overhead = 0.0;
2742 if (G1AccountConcurrentOverhead)
2743 conc_overhead = COTracker::totalPredConcOverhead();
2744 _mmu_tracker->update_conc_overhead(conc_overhead);
2745 #if 0
2746 gclog_or_tty->print(" CO %1.4lf TARGET %1.4lf",
2747 conc_overhead, _mmu_tracker->max_gc_time());
2748 #endif
2749 }
2752 size_t G1CollectorPolicy::max_regions(int purpose) {
2753 switch (purpose) {
2754 case GCAllocForSurvived:
2755 return _max_survivor_regions;
2756 case GCAllocForTenured:
2757 return REGIONS_UNLIMITED;
2758 default:
2759 ShouldNotReachHere();
2760 return REGIONS_UNLIMITED;
2761 };
2762 }
2764 // Calculates survivor space parameters.
2765 void G1CollectorPolicy::calculate_survivors_policy()
2766 {
2767 if (!G1UseSurvivorSpace) {
2768 return;
2769 }
2770 if (G1FixedSurvivorSpaceSize == 0) {
2771 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2772 } else {
2773 _max_survivor_regions = G1FixedSurvivorSpaceSize;
2774 }
2776 if (G1FixedTenuringThreshold) {
2777 _tenuring_threshold = MaxTenuringThreshold;
2778 } else {
2779 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2780 HeapRegion::GrainWords * _max_survivor_regions);
2781 }
2782 }
2785 void
2786 G1CollectorPolicy_BestRegionsFirst::
2787 set_single_region_collection_set(HeapRegion* hr) {
2788 G1CollectorPolicy::set_single_region_collection_set(hr);
2789 _collectionSetChooser->removeRegion(hr);
2790 }
2793 bool
2794 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
2795 word_size) {
2796 assert(_g1->regions_accounted_for(), "Region leakage!");
2797 // Initiate a pause when we reach the steady-state "used" target.
2798 size_t used_hard = (_g1->capacity() / 100) * G1SteadyStateUsed;
2799 size_t used_soft =
2800 MAX2((_g1->capacity() / 100) * (G1SteadyStateUsed - G1SteadyStateUsedDelta),
2801 used_hard/2);
2802 size_t used = _g1->used();
2804 double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
2806 size_t young_list_length = _g1->young_list_length();
2807 size_t young_list_max_length = _young_list_target_length;
2808 if (G1FixedEdenSize) {
2809 young_list_max_length -= _max_survivor_regions;
2810 }
2811 bool reached_target_length = young_list_length >= young_list_max_length;
2813 if (in_young_gc_mode()) {
2814 if (reached_target_length) {
2815 assert( young_list_length > 0 && _g1->young_list_length() > 0,
2816 "invariant" );
2817 _target_pause_time_ms = max_pause_time_ms;
2818 return true;
2819 }
2820 } else {
2821 guarantee( false, "should not reach here" );
2822 }
2824 return false;
2825 }
2827 #ifndef PRODUCT
2828 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2829 CollectionSetChooser* _chooser;
2830 public:
2831 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2832 _chooser(chooser) {}
2834 bool doHeapRegion(HeapRegion* r) {
2835 if (!r->continuesHumongous()) {
2836 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2837 }
2838 return false;
2839 }
2840 };
2842 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2843 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2844 _g1->heap_region_iterate(&cl);
2845 return true;
2846 }
2847 #endif
2849 void
2850 G1CollectorPolicy_BestRegionsFirst::
2851 record_collection_pause_start(double start_time_sec, size_t start_used) {
2852 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2853 }
2855 class NextNonCSElemFinder: public HeapRegionClosure {
2856 HeapRegion* _res;
2857 public:
2858 NextNonCSElemFinder(): _res(NULL) {}
2859 bool doHeapRegion(HeapRegion* r) {
2860 if (!r->in_collection_set()) {
2861 _res = r;
2862 return true;
2863 } else {
2864 return false;
2865 }
2866 }
2867 HeapRegion* res() { return _res; }
2868 };
2870 class KnownGarbageClosure: public HeapRegionClosure {
2871 CollectionSetChooser* _hrSorted;
2873 public:
2874 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2875 _hrSorted(hrSorted)
2876 {}
2878 bool doHeapRegion(HeapRegion* r) {
2879 // We only include humongous regions in collection
2880 // sets when concurrent mark shows that their contained object is
2881 // unreachable.
2883 // Do we have any marking information for this region?
2884 if (r->is_marked()) {
2885 // We don't include humongous regions in collection
2886 // sets because we collect them immediately at the end of a marking
2887 // cycle. We also don't include young regions because we *must*
2888 // include them in the next collection pause.
2889 if (!r->isHumongous() && !r->is_young()) {
2890 _hrSorted->addMarkedHeapRegion(r);
2891 }
2892 }
2893 return false;
2894 }
2895 };
2897 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2898 CollectionSetChooser* _hrSorted;
2899 jint _marked_regions_added;
2900 jint _chunk_size;
2901 jint _cur_chunk_idx;
2902 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2903 int _worker;
2904 int _invokes;
2906 void get_new_chunk() {
2907 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2908 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2909 }
2910 void add_region(HeapRegion* r) {
2911 if (_cur_chunk_idx == _cur_chunk_end) {
2912 get_new_chunk();
2913 }
2914 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2915 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2916 _marked_regions_added++;
2917 _cur_chunk_idx++;
2918 }
2920 public:
2921 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2922 jint chunk_size,
2923 int worker) :
2924 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2925 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2926 _invokes(0)
2927 {}
2929 bool doHeapRegion(HeapRegion* r) {
2930 // We only include humongous regions in collection
2931 // sets when concurrent mark shows that their contained object is
2932 // unreachable.
2933 _invokes++;
2935 // Do we have any marking information for this region?
2936 if (r->is_marked()) {
2937 // We don't include humongous regions in collection
2938 // sets because we collect them immediately at the end of a marking
2939 // cycle.
2940 // We also do not include young regions in collection sets
2941 if (!r->isHumongous() && !r->is_young()) {
2942 add_region(r);
2943 }
2944 }
2945 return false;
2946 }
2947 jint marked_regions_added() { return _marked_regions_added; }
2948 int invokes() { return _invokes; }
2949 };
2951 class ParKnownGarbageTask: public AbstractGangTask {
2952 CollectionSetChooser* _hrSorted;
2953 jint _chunk_size;
2954 G1CollectedHeap* _g1;
2955 public:
2956 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2957 AbstractGangTask("ParKnownGarbageTask"),
2958 _hrSorted(hrSorted), _chunk_size(chunk_size),
2959 _g1(G1CollectedHeap::heap())
2960 {}
2962 void work(int i) {
2963 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2964 // Back to zero for the claim value.
2965 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2966 HeapRegion::InitialClaimValue);
2967 jint regions_added = parKnownGarbageCl.marked_regions_added();
2968 _hrSorted->incNumMarkedHeapRegions(regions_added);
2969 if (G1PrintParCleanupStats) {
2970 gclog_or_tty->print(" Thread %d called %d times, added %d regions to list.\n",
2971 i, parKnownGarbageCl.invokes(), regions_added);
2972 }
2973 }
2974 };
2976 void
2977 G1CollectorPolicy_BestRegionsFirst::
2978 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2979 size_t max_live_bytes) {
2980 double start;
2981 if (G1PrintParCleanupStats) start = os::elapsedTime();
2982 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2984 _collectionSetChooser->clearMarkedHeapRegions();
2985 double clear_marked_end;
2986 if (G1PrintParCleanupStats) {
2987 clear_marked_end = os::elapsedTime();
2988 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2989 (clear_marked_end - start)*1000.0);
2990 }
2991 if (ParallelGCThreads > 0) {
2992 const size_t OverpartitionFactor = 4;
2993 const size_t MinChunkSize = 8;
2994 const size_t ChunkSize =
2995 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2996 MinChunkSize);
2997 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2998 ChunkSize);
2999 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
3000 (int) ChunkSize);
3001 _g1->workers()->run_task(&parKnownGarbageTask);
3003 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3004 "sanity check");
3005 } else {
3006 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
3007 _g1->heap_region_iterate(&knownGarbagecl);
3008 }
3009 double known_garbage_end;
3010 if (G1PrintParCleanupStats) {
3011 known_garbage_end = os::elapsedTime();
3012 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
3013 (known_garbage_end - clear_marked_end)*1000.0);
3014 }
3015 _collectionSetChooser->sortMarkedHeapRegions();
3016 double sort_end;
3017 if (G1PrintParCleanupStats) {
3018 sort_end = os::elapsedTime();
3019 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
3020 (sort_end - known_garbage_end)*1000.0);
3021 }
3023 record_concurrent_mark_cleanup_end_work2();
3024 double work2_end;
3025 if (G1PrintParCleanupStats) {
3026 work2_end = os::elapsedTime();
3027 gclog_or_tty->print_cr(" work2: %8.3f ms.",
3028 (work2_end - sort_end)*1000.0);
3029 }
3030 }
3032 // Add the heap region to the collection set and return the conservative
3033 // estimate of the number of live bytes.
3034 void G1CollectorPolicy::
3035 add_to_collection_set(HeapRegion* hr) {
3036 if (G1TraceRegions) {
3037 gclog_or_tty->print_cr("added region to cset %d:["PTR_FORMAT", "PTR_FORMAT"], "
3038 "top "PTR_FORMAT", young %s",
3039 hr->hrs_index(), hr->bottom(), hr->end(),
3040 hr->top(), (hr->is_young()) ? "YES" : "NO");
3041 }
3043 if (_g1->mark_in_progress())
3044 _g1->concurrent_mark()->registerCSetRegion(hr);
3046 assert(!hr->in_collection_set(),
3047 "should not already be in the CSet");
3048 hr->set_in_collection_set(true);
3049 hr->set_next_in_collection_set(_collection_set);
3050 _collection_set = hr;
3051 _collection_set_size++;
3052 _collection_set_bytes_used_before += hr->used();
3053 _g1->register_region_with_in_cset_fast_test(hr);
3054 }
3056 void
3057 G1CollectorPolicy_BestRegionsFirst::
3058 choose_collection_set(HeapRegion* pop_region) {
3059 double non_young_start_time_sec;
3060 start_recording_regions();
3062 if (pop_region != NULL) {
3063 _target_pause_time_ms = (double) G1MaxPauseTimeMS;
3064 } else {
3065 guarantee(_target_pause_time_ms > -1.0,
3066 "_target_pause_time_ms should have been set!");
3067 }
3069 // pop region is either null (and so is CS), or else it *is* the CS.
3070 assert(_collection_set == pop_region, "Precondition");
3072 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
3073 double predicted_pause_time_ms = base_time_ms;
3075 double target_time_ms = _target_pause_time_ms;
3076 double time_remaining_ms = target_time_ms - base_time_ms;
3078 // the 10% and 50% values are arbitrary...
3079 if (time_remaining_ms < 0.10*target_time_ms) {
3080 time_remaining_ms = 0.50 * target_time_ms;
3081 _within_target = false;
3082 } else {
3083 _within_target = true;
3084 }
3086 // We figure out the number of bytes available for future to-space.
3087 // For new regions without marking information, we must assume the
3088 // worst-case of complete survival. If we have marking information for a
3089 // region, we can bound the amount of live data. We can add a number of
3090 // such regions, as long as the sum of the live data bounds does not
3091 // exceed the available evacuation space.
3092 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
3094 size_t expansion_bytes =
3095 _g1->expansion_regions() * HeapRegion::GrainBytes;
3097 if (pop_region == NULL) {
3098 _collection_set_bytes_used_before = 0;
3099 _collection_set_size = 0;
3100 }
3102 // Adjust for expansion and slop.
3103 max_live_bytes = max_live_bytes + expansion_bytes;
3105 assert(pop_region != NULL || _g1->regions_accounted_for(), "Region leakage!");
3107 HeapRegion* hr;
3108 if (in_young_gc_mode()) {
3109 double young_start_time_sec = os::elapsedTime();
3111 if (G1PolicyVerbose > 0) {
3112 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
3113 _g1->young_list_length());
3114 }
3115 _young_cset_length = 0;
3116 _last_young_gc_full = full_young_gcs() ? true : false;
3117 if (_last_young_gc_full)
3118 ++_full_young_pause_num;
3119 else
3120 ++_partial_young_pause_num;
3121 hr = _g1->pop_region_from_young_list();
3122 while (hr != NULL) {
3124 assert( hr->young_index_in_cset() == -1, "invariant" );
3125 assert( hr->age_in_surv_rate_group() != -1, "invariant" );
3126 hr->set_young_index_in_cset((int) _young_cset_length);
3128 ++_young_cset_length;
3129 double predicted_time_ms = predict_region_elapsed_time_ms(hr, true);
3130 time_remaining_ms -= predicted_time_ms;
3131 predicted_pause_time_ms += predicted_time_ms;
3132 if (hr == pop_region) {
3133 // The popular region was young. Skip over it.
3134 assert(hr->in_collection_set(), "It's the pop region.");
3135 } else {
3136 assert(!hr->in_collection_set(), "It's not the pop region.");
3137 add_to_collection_set(hr);
3138 record_cset_region(hr, true);
3139 }
3140 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
3141 if (G1PolicyVerbose > 0) {
3142 gclog_or_tty->print_cr(" Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.",
3143 hr->bottom(), hr->end());
3144 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
3145 max_live_bytes/K);
3146 }
3147 hr = _g1->pop_region_from_young_list();
3148 }
3150 record_scan_only_regions(_g1->young_list_scan_only_length());
3152 double young_end_time_sec = os::elapsedTime();
3153 _recorded_young_cset_choice_time_ms =
3154 (young_end_time_sec - young_start_time_sec) * 1000.0;
3156 non_young_start_time_sec = os::elapsedTime();
3158 if (_young_cset_length > 0 && _last_young_gc_full) {
3159 // don't bother adding more regions...
3160 goto choose_collection_set_end;
3161 }
3162 } else if (pop_region != NULL) {
3163 // We're not in young mode, and we chose a popular region; don't choose
3164 // any more.
3165 return;
3166 }
3168 if (!in_young_gc_mode() || !full_young_gcs()) {
3169 bool should_continue = true;
3170 NumberSeq seq;
3171 double avg_prediction = 100000000000000000.0; // something very large
3172 do {
3173 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
3174 avg_prediction);
3175 if (hr != NULL && !hr->popular()) {
3176 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
3177 time_remaining_ms -= predicted_time_ms;
3178 predicted_pause_time_ms += predicted_time_ms;
3179 add_to_collection_set(hr);
3180 record_cset_region(hr, false);
3181 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
3182 if (G1PolicyVerbose > 0) {
3183 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
3184 max_live_bytes/K);
3185 }
3186 seq.add(predicted_time_ms);
3187 avg_prediction = seq.avg() + seq.sd();
3188 }
3189 should_continue =
3190 ( hr != NULL) &&
3191 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
3192 : _collection_set_size < _young_list_fixed_length );
3193 } while (should_continue);
3195 if (!adaptive_young_list_length() &&
3196 _collection_set_size < _young_list_fixed_length)
3197 _should_revert_to_full_young_gcs = true;
3198 }
3200 choose_collection_set_end:
3201 count_CS_bytes_used();
3203 end_recording_regions();
3205 double non_young_end_time_sec = os::elapsedTime();
3206 _recorded_non_young_cset_choice_time_ms =
3207 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3208 }
3210 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3211 G1CollectorPolicy::record_full_collection_end();
3212 _collectionSetChooser->updateAfterFullCollection();
3213 }
3215 void G1CollectorPolicy_BestRegionsFirst::
3216 expand_if_possible(size_t numRegions) {
3217 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3218 _g1->expand(expansion_bytes);
3219 }
3221 void G1CollectorPolicy_BestRegionsFirst::
3222 record_collection_pause_end(bool popular, bool abandoned) {
3223 G1CollectorPolicy::record_collection_pause_end(popular, abandoned);
3224 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3225 }
3227 // Local Variables: ***
3228 // c-indentation-style: gnu ***
3229 // End: ***