Fri, 18 Feb 2011 10:07:34 -0800
7020042: G1: Partially remove fix for 6994628
Summary: Disable reference discovery and processing during concurrent marking by disabling fix for 6994628.
Reviewed-by: tonyp, ysr
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/shared/gcPolicyCounters.hpp"
33 #include "runtime/arguments.hpp"
34 #include "runtime/java.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "utilities/debug.hpp"
38 #define PREDICTIONS_VERBOSE 0
40 // <NEW PREDICTION>
42 // Different defaults for different number of GC threads
43 // They were chosen by running GCOld and SPECjbb on debris with different
44 // numbers of GC threads and choosing them based on the results
46 // all the same
47 static double rs_length_diff_defaults[] = {
48 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
49 };
51 static double cost_per_card_ms_defaults[] = {
52 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
53 };
55 // all the same
56 static double fully_young_cards_per_entry_ratio_defaults[] = {
57 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
58 };
60 static double cost_per_entry_ms_defaults[] = {
61 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
62 };
64 static double cost_per_byte_ms_defaults[] = {
65 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
66 };
68 // these should be pretty consistent
69 static double constant_other_time_ms_defaults[] = {
70 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
71 };
74 static double young_other_cost_per_region_ms_defaults[] = {
75 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
76 };
78 static double non_young_other_cost_per_region_ms_defaults[] = {
79 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
80 };
82 // </NEW PREDICTION>
84 // Help class for avoiding interleaved logging
85 class LineBuffer: public StackObj {
87 private:
88 static const int BUFFER_LEN = 1024;
89 static const int INDENT_CHARS = 3;
90 char _buffer[BUFFER_LEN];
91 int _indent_level;
92 int _cur;
94 void vappend(const char* format, va_list ap) {
95 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
96 if (res != -1) {
97 _cur += res;
98 } else {
99 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
100 _buffer[BUFFER_LEN -1] = 0;
101 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
102 }
103 }
105 public:
106 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
107 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
108 _buffer[_cur] = ' ';
109 }
110 }
112 #ifndef PRODUCT
113 ~LineBuffer() {
114 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
115 }
116 #endif
118 void append(const char* format, ...) {
119 va_list ap;
120 va_start(ap, format);
121 vappend(format, ap);
122 va_end(ap);
123 }
125 void append_and_print_cr(const char* format, ...) {
126 va_list ap;
127 va_start(ap, format);
128 vappend(format, ap);
129 va_end(ap);
130 gclog_or_tty->print_cr("%s", _buffer);
131 _cur = _indent_level * INDENT_CHARS;
132 }
133 };
135 G1CollectorPolicy::G1CollectorPolicy() :
136 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
137 ? ParallelGCThreads : 1),
140 _n_pauses(0),
141 _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
142 _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
143 _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
144 _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
145 _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
146 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
147 _all_pause_times_ms(new NumberSeq()),
148 _stop_world_start(0.0),
149 _all_stop_world_times_ms(new NumberSeq()),
150 _all_yield_times_ms(new NumberSeq()),
152 _all_mod_union_times_ms(new NumberSeq()),
154 _summary(new Summary()),
156 #ifndef PRODUCT
157 _cur_clear_ct_time_ms(0.0),
158 _min_clear_cc_time_ms(-1.0),
159 _max_clear_cc_time_ms(-1.0),
160 _cur_clear_cc_time_ms(0.0),
161 _cum_clear_cc_time_ms(0.0),
162 _num_cc_clears(0L),
163 #endif
165 _region_num_young(0),
166 _region_num_tenured(0),
167 _prev_region_num_young(0),
168 _prev_region_num_tenured(0),
170 _aux_num(10),
171 _all_aux_times_ms(new NumberSeq[_aux_num]),
172 _cur_aux_start_times_ms(new double[_aux_num]),
173 _cur_aux_times_ms(new double[_aux_num]),
174 _cur_aux_times_set(new bool[_aux_num]),
176 _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
177 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
178 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
180 // <NEW PREDICTION>
182 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
183 _prev_collection_pause_end_ms(0.0),
184 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
185 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
186 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
187 _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
188 _partially_young_cards_per_entry_ratio_seq(
189 new TruncatedSeq(TruncatedSeqLength)),
190 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
191 _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
192 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
193 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
194 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
195 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
196 _non_young_other_cost_per_region_ms_seq(
197 new TruncatedSeq(TruncatedSeqLength)),
199 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
200 _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
201 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
203 _pause_time_target_ms((double) MaxGCPauseMillis),
205 // </NEW PREDICTION>
207 _in_young_gc_mode(false),
208 _full_young_gcs(true),
209 _full_young_pause_num(0),
210 _partial_young_pause_num(0),
212 _during_marking(false),
213 _in_marking_window(false),
214 _in_marking_window_im(false),
216 _known_garbage_ratio(0.0),
217 _known_garbage_bytes(0),
219 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
221 _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
223 _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
224 _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
226 _recent_avg_pause_time_ratio(0.0),
227 _num_markings(0),
228 _n_marks(0),
229 _n_pauses_at_mark_end(0),
231 _all_full_gc_times_ms(new NumberSeq()),
233 // G1PausesBtwnConcMark defaults to -1
234 // so the hack is to do the cast QQQ FIXME
235 _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
236 _n_marks_since_last_pause(0),
237 _initiate_conc_mark_if_possible(false),
238 _during_initial_mark_pause(false),
239 _should_revert_to_full_young_gcs(false),
240 _last_full_young_gc(false),
242 _prev_collection_pause_used_at_end_bytes(0),
244 _collection_set(NULL),
245 _collection_set_size(0),
246 _collection_set_bytes_used_before(0),
248 // Incremental CSet attributes
249 _inc_cset_build_state(Inactive),
250 _inc_cset_head(NULL),
251 _inc_cset_tail(NULL),
252 _inc_cset_size(0),
253 _inc_cset_young_index(0),
254 _inc_cset_bytes_used_before(0),
255 _inc_cset_max_finger(NULL),
256 _inc_cset_recorded_young_bytes(0),
257 _inc_cset_recorded_rs_lengths(0),
258 _inc_cset_predicted_elapsed_time_ms(0.0),
259 _inc_cset_predicted_bytes_to_copy(0),
261 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
262 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
263 #endif // _MSC_VER
265 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
266 G1YoungSurvRateNumRegionsSummary)),
267 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
268 G1YoungSurvRateNumRegionsSummary)),
269 // add here any more surv rate groups
270 _recorded_survivor_regions(0),
271 _recorded_survivor_head(NULL),
272 _recorded_survivor_tail(NULL),
273 _survivors_age_table(true),
275 _gc_overhead_perc(0.0)
277 {
278 // Set up the region size and associated fields. Given that the
279 // policy is created before the heap, we have to set this up here,
280 // so it's done as soon as possible.
281 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
282 HeapRegionRemSet::setup_remset_size();
284 // Verify PLAB sizes
285 const uint region_size = HeapRegion::GrainWords;
286 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
287 char buffer[128];
288 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
289 OldPLABSize > region_size ? "Old" : "Young", region_size);
290 vm_exit_during_initialization(buffer);
291 }
293 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
294 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
296 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
297 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
298 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
300 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
301 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
303 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
305 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
307 _par_last_termination_times_ms = new double[_parallel_gc_threads];
308 _par_last_termination_attempts = new double[_parallel_gc_threads];
309 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
310 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
312 // start conservatively
313 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
315 // <NEW PREDICTION>
317 int index;
318 if (ParallelGCThreads == 0)
319 index = 0;
320 else if (ParallelGCThreads > 8)
321 index = 7;
322 else
323 index = ParallelGCThreads - 1;
325 _pending_card_diff_seq->add(0.0);
326 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
327 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
328 _fully_young_cards_per_entry_ratio_seq->add(
329 fully_young_cards_per_entry_ratio_defaults[index]);
330 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
331 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
332 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
333 _young_other_cost_per_region_ms_seq->add(
334 young_other_cost_per_region_ms_defaults[index]);
335 _non_young_other_cost_per_region_ms_seq->add(
336 non_young_other_cost_per_region_ms_defaults[index]);
338 // </NEW PREDICTION>
340 // Below, we might need to calculate the pause time target based on
341 // the pause interval. When we do so we are going to give G1 maximum
342 // flexibility and allow it to do pauses when it needs to. So, we'll
343 // arrange that the pause interval to be pause time target + 1 to
344 // ensure that a) the pause time target is maximized with respect to
345 // the pause interval and b) we maintain the invariant that pause
346 // time target < pause interval. If the user does not want this
347 // maximum flexibility, they will have to set the pause interval
348 // explicitly.
350 // First make sure that, if either parameter is set, its value is
351 // reasonable.
352 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
353 if (MaxGCPauseMillis < 1) {
354 vm_exit_during_initialization("MaxGCPauseMillis should be "
355 "greater than 0");
356 }
357 }
358 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
359 if (GCPauseIntervalMillis < 1) {
360 vm_exit_during_initialization("GCPauseIntervalMillis should be "
361 "greater than 0");
362 }
363 }
365 // Then, if the pause time target parameter was not set, set it to
366 // the default value.
367 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
368 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
369 // The default pause time target in G1 is 200ms
370 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
371 } else {
372 // We do not allow the pause interval to be set without the
373 // pause time target
374 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
375 "without setting MaxGCPauseMillis");
376 }
377 }
379 // Then, if the interval parameter was not set, set it according to
380 // the pause time target (this will also deal with the case when the
381 // pause time target is the default value).
382 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
383 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
384 }
386 // Finally, make sure that the two parameters are consistent.
387 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
388 char buffer[256];
389 jio_snprintf(buffer, 256,
390 "MaxGCPauseMillis (%u) should be less than "
391 "GCPauseIntervalMillis (%u)",
392 MaxGCPauseMillis, GCPauseIntervalMillis);
393 vm_exit_during_initialization(buffer);
394 }
396 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
397 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
398 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
399 _sigma = (double) G1ConfidencePercent / 100.0;
401 // start conservatively (around 50ms is about right)
402 _concurrent_mark_init_times_ms->add(0.05);
403 _concurrent_mark_remark_times_ms->add(0.05);
404 _concurrent_mark_cleanup_times_ms->add(0.20);
405 _tenuring_threshold = MaxTenuringThreshold;
407 // if G1FixedSurvivorSpaceSize is 0 which means the size is not
408 // fixed, then _max_survivor_regions will be calculated at
409 // calculate_young_list_target_length during initialization
410 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
412 assert(GCTimeRatio > 0,
413 "we should have set it to a default value set_g1_gc_flags() "
414 "if a user set it to 0");
415 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
417 initialize_all();
418 }
420 // Increment "i", mod "len"
421 static void inc_mod(int& i, int len) {
422 i++; if (i == len) i = 0;
423 }
425 void G1CollectorPolicy::initialize_flags() {
426 set_min_alignment(HeapRegion::GrainBytes);
427 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
428 if (SurvivorRatio < 1) {
429 vm_exit_during_initialization("Invalid survivor ratio specified");
430 }
431 CollectorPolicy::initialize_flags();
432 }
434 // The easiest way to deal with the parsing of the NewSize /
435 // MaxNewSize / etc. parameteres is to re-use the code in the
436 // TwoGenerationCollectorPolicy class. This is similar to what
437 // ParallelScavenge does with its GenerationSizer class (see
438 // ParallelScavengeHeap::initialize()). We might change this in the
439 // future, but it's a good start.
440 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
441 size_t size_to_region_num(size_t byte_size) {
442 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
443 }
445 public:
446 G1YoungGenSizer() {
447 initialize_flags();
448 initialize_size_info();
449 }
451 size_t min_young_region_num() {
452 return size_to_region_num(_min_gen0_size);
453 }
454 size_t initial_young_region_num() {
455 return size_to_region_num(_initial_gen0_size);
456 }
457 size_t max_young_region_num() {
458 return size_to_region_num(_max_gen0_size);
459 }
460 };
462 void G1CollectorPolicy::init() {
463 // Set aside an initial future to_space.
464 _g1 = G1CollectedHeap::heap();
466 assert(Heap_lock->owned_by_self(), "Locking discipline.");
468 initialize_gc_policy_counters();
470 if (G1Gen) {
471 _in_young_gc_mode = true;
473 G1YoungGenSizer sizer;
474 size_t initial_region_num = sizer.initial_young_region_num();
476 if (UseAdaptiveSizePolicy) {
477 set_adaptive_young_list_length(true);
478 _young_list_fixed_length = 0;
479 } else {
480 set_adaptive_young_list_length(false);
481 _young_list_fixed_length = initial_region_num;
482 }
483 _free_regions_at_end_of_collection = _g1->free_regions();
484 calculate_young_list_min_length();
485 guarantee( _young_list_min_length == 0, "invariant, not enough info" );
486 calculate_young_list_target_length();
487 } else {
488 _young_list_fixed_length = 0;
489 _in_young_gc_mode = false;
490 }
492 // We may immediately start allocating regions and placing them on the
493 // collection set list. Initialize the per-collection set info
494 start_incremental_cset_building();
495 }
497 // Create the jstat counters for the policy.
498 void G1CollectorPolicy::initialize_gc_policy_counters()
499 {
500 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
501 }
503 void G1CollectorPolicy::calculate_young_list_min_length() {
504 _young_list_min_length = 0;
506 if (!adaptive_young_list_length())
507 return;
509 if (_alloc_rate_ms_seq->num() > 3) {
510 double now_sec = os::elapsedTime();
511 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
512 double alloc_rate_ms = predict_alloc_rate_ms();
513 size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
514 size_t current_region_num = _g1->young_list()->length();
515 _young_list_min_length = min_regions + current_region_num;
516 }
517 }
519 void G1CollectorPolicy::calculate_young_list_target_length() {
520 if (adaptive_young_list_length()) {
521 size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
522 calculate_young_list_target_length(rs_lengths);
523 } else {
524 if (full_young_gcs())
525 _young_list_target_length = _young_list_fixed_length;
526 else
527 _young_list_target_length = _young_list_fixed_length / 2;
528 }
530 // Make sure we allow the application to allocate at least one
531 // region before we need to do a collection again.
532 size_t min_length = _g1->young_list()->length() + 1;
533 _young_list_target_length = MAX2(_young_list_target_length, min_length);
534 calculate_max_gc_locker_expansion();
535 calculate_survivors_policy();
536 }
538 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
539 guarantee( adaptive_young_list_length(), "pre-condition" );
540 guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
542 double start_time_sec = os::elapsedTime();
543 size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
544 min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
545 size_t reserve_regions =
546 (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
548 if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
549 // we are in fully-young mode and there are free regions in the heap
551 double survivor_regions_evac_time =
552 predict_survivor_regions_evac_time();
554 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
555 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
556 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
557 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
558 double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
559 + survivor_regions_evac_time;
561 // the result
562 size_t final_young_length = 0;
564 size_t init_free_regions =
565 MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
567 // if we're still under the pause target...
568 if (base_time_ms <= target_pause_time_ms) {
569 // We make sure that the shortest young length that makes sense
570 // fits within the target pause time.
571 size_t min_young_length = 1;
573 if (predict_will_fit(min_young_length, base_time_ms,
574 init_free_regions, target_pause_time_ms)) {
575 // The shortest young length will fit within the target pause time;
576 // we'll now check whether the absolute maximum number of young
577 // regions will fit in the target pause time. If not, we'll do
578 // a binary search between min_young_length and max_young_length
579 size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
580 size_t max_young_length = abs_max_young_length;
582 if (max_young_length > min_young_length) {
583 // Let's check if the initial max young length will fit within the
584 // target pause. If so then there is no need to search for a maximal
585 // young length - we'll return the initial maximum
587 if (predict_will_fit(max_young_length, base_time_ms,
588 init_free_regions, target_pause_time_ms)) {
589 // The maximum young length will satisfy the target pause time.
590 // We are done so set min young length to this maximum length.
591 // The code after the loop will then set final_young_length using
592 // the value cached in the minimum length.
593 min_young_length = max_young_length;
594 } else {
595 // The maximum possible number of young regions will not fit within
596 // the target pause time so let's search....
598 size_t diff = (max_young_length - min_young_length) / 2;
599 max_young_length = min_young_length + diff;
601 while (max_young_length > min_young_length) {
602 if (predict_will_fit(max_young_length, base_time_ms,
603 init_free_regions, target_pause_time_ms)) {
605 // The current max young length will fit within the target
606 // pause time. Note we do not exit the loop here. By setting
607 // min = max, and then increasing the max below means that
608 // we will continue searching for an upper bound in the
609 // range [max..max+diff]
610 min_young_length = max_young_length;
611 }
612 diff = (max_young_length - min_young_length) / 2;
613 max_young_length = min_young_length + diff;
614 }
615 // the above loop found a maximal young length that will fit
616 // within the target pause time.
617 }
618 assert(min_young_length <= abs_max_young_length, "just checking");
619 }
620 final_young_length = min_young_length;
621 }
622 }
623 // and we're done!
625 // we should have at least one region in the target young length
626 _young_list_target_length =
627 final_young_length + _recorded_survivor_regions;
629 // let's keep an eye of how long we spend on this calculation
630 // right now, I assume that we'll print it when we need it; we
631 // should really adde it to the breakdown of a pause
632 double end_time_sec = os::elapsedTime();
633 double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
635 #ifdef TRACE_CALC_YOUNG_LENGTH
636 // leave this in for debugging, just in case
637 gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
638 "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
639 target_pause_time_ms,
640 _young_list_target_length
641 elapsed_time_ms,
642 full_young_gcs() ? "full" : "partial",
643 during_initial_mark_pause() ? " i-m" : "",
644 _in_marking_window,
645 _in_marking_window_im);
646 #endif // TRACE_CALC_YOUNG_LENGTH
648 if (_young_list_target_length < _young_list_min_length) {
649 // bummer; this means that, if we do a pause when the maximal
650 // length dictates, we'll violate the pause spacing target (the
651 // min length was calculate based on the application's current
652 // alloc rate);
654 // so, we have to bite the bullet, and allocate the minimum
655 // number. We'll violate our target, but we just can't meet it.
657 #ifdef TRACE_CALC_YOUNG_LENGTH
658 // leave this in for debugging, just in case
659 gclog_or_tty->print_cr("adjusted target length from "
660 SIZE_FORMAT " to " SIZE_FORMAT,
661 _young_list_target_length, _young_list_min_length);
662 #endif // TRACE_CALC_YOUNG_LENGTH
664 _young_list_target_length = _young_list_min_length;
665 }
666 } else {
667 // we are in a partially-young mode or we've run out of regions (due
668 // to evacuation failure)
670 #ifdef TRACE_CALC_YOUNG_LENGTH
671 // leave this in for debugging, just in case
672 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
673 _young_list_min_length);
674 #endif // TRACE_CALC_YOUNG_LENGTH
675 // we'll do the pause as soon as possible by choosing the minimum
676 _young_list_target_length = _young_list_min_length;
677 }
679 _rs_lengths_prediction = rs_lengths;
680 }
682 // This is used by: calculate_young_list_target_length(rs_length). It
683 // returns true iff:
684 // the predicted pause time for the given young list will not overflow
685 // the target pause time
686 // and:
687 // the predicted amount of surviving data will not overflow the
688 // the amount of free space available for survivor regions.
689 //
690 bool
691 G1CollectorPolicy::predict_will_fit(size_t young_length,
692 double base_time_ms,
693 size_t init_free_regions,
694 double target_pause_time_ms) {
696 if (young_length >= init_free_regions)
697 // end condition 1: not enough space for the young regions
698 return false;
700 double accum_surv_rate_adj = 0.0;
701 double accum_surv_rate =
702 accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
704 size_t bytes_to_copy =
705 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
707 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
709 double young_other_time_ms =
710 predict_young_other_time_ms(young_length);
712 double pause_time_ms =
713 base_time_ms + copy_time_ms + young_other_time_ms;
715 if (pause_time_ms > target_pause_time_ms)
716 // end condition 2: over the target pause time
717 return false;
719 size_t free_bytes =
720 (init_free_regions - young_length) * HeapRegion::GrainBytes;
722 if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
723 // end condition 3: out of to-space (conservatively)
724 return false;
726 // success!
727 return true;
728 }
730 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
731 double survivor_regions_evac_time = 0.0;
732 for (HeapRegion * r = _recorded_survivor_head;
733 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
734 r = r->get_next_young_region()) {
735 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
736 }
737 return survivor_regions_evac_time;
738 }
740 void G1CollectorPolicy::check_prediction_validity() {
741 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
743 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
744 if (rs_lengths > _rs_lengths_prediction) {
745 // add 10% to avoid having to recalculate often
746 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
747 calculate_young_list_target_length(rs_lengths_prediction);
748 }
749 }
751 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
752 bool is_tlab,
753 bool* gc_overhead_limit_was_exceeded) {
754 guarantee(false, "Not using this policy feature yet.");
755 return NULL;
756 }
758 // This method controls how a collector handles one or more
759 // of its generations being fully allocated.
760 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
761 bool is_tlab) {
762 guarantee(false, "Not using this policy feature yet.");
763 return NULL;
764 }
767 #ifndef PRODUCT
768 bool G1CollectorPolicy::verify_young_ages() {
769 HeapRegion* head = _g1->young_list()->first_region();
770 return
771 verify_young_ages(head, _short_lived_surv_rate_group);
772 // also call verify_young_ages on any additional surv rate groups
773 }
775 bool
776 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
777 SurvRateGroup *surv_rate_group) {
778 guarantee( surv_rate_group != NULL, "pre-condition" );
780 const char* name = surv_rate_group->name();
781 bool ret = true;
782 int prev_age = -1;
784 for (HeapRegion* curr = head;
785 curr != NULL;
786 curr = curr->get_next_young_region()) {
787 SurvRateGroup* group = curr->surv_rate_group();
788 if (group == NULL && !curr->is_survivor()) {
789 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
790 ret = false;
791 }
793 if (surv_rate_group == group) {
794 int age = curr->age_in_surv_rate_group();
796 if (age < 0) {
797 gclog_or_tty->print_cr("## %s: encountered negative age", name);
798 ret = false;
799 }
801 if (age <= prev_age) {
802 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
803 "(%d, %d)", name, age, prev_age);
804 ret = false;
805 }
806 prev_age = age;
807 }
808 }
810 return ret;
811 }
812 #endif // PRODUCT
814 void G1CollectorPolicy::record_full_collection_start() {
815 _cur_collection_start_sec = os::elapsedTime();
816 // Release the future to-space so that it is available for compaction into.
817 _g1->set_full_collection();
818 }
820 void G1CollectorPolicy::record_full_collection_end() {
821 // Consider this like a collection pause for the purposes of allocation
822 // since last pause.
823 double end_sec = os::elapsedTime();
824 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
825 double full_gc_time_ms = full_gc_time_sec * 1000.0;
827 _all_full_gc_times_ms->add(full_gc_time_ms);
829 update_recent_gc_times(end_sec, full_gc_time_ms);
831 _g1->clear_full_collection();
833 // "Nuke" the heuristics that control the fully/partially young GC
834 // transitions and make sure we start with fully young GCs after the
835 // Full GC.
836 set_full_young_gcs(true);
837 _last_full_young_gc = false;
838 _should_revert_to_full_young_gcs = false;
839 clear_initiate_conc_mark_if_possible();
840 clear_during_initial_mark_pause();
841 _known_garbage_bytes = 0;
842 _known_garbage_ratio = 0.0;
843 _in_marking_window = false;
844 _in_marking_window_im = false;
846 _short_lived_surv_rate_group->start_adding_regions();
847 // also call this on any additional surv rate groups
849 record_survivor_regions(0, NULL, NULL);
851 _prev_region_num_young = _region_num_young;
852 _prev_region_num_tenured = _region_num_tenured;
854 _free_regions_at_end_of_collection = _g1->free_regions();
855 // Reset survivors SurvRateGroup.
856 _survivor_surv_rate_group->reset();
857 calculate_young_list_min_length();
858 calculate_young_list_target_length();
859 }
861 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
862 _bytes_in_to_space_before_gc += bytes;
863 }
865 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
866 _bytes_in_to_space_after_gc += bytes;
867 }
869 void G1CollectorPolicy::record_stop_world_start() {
870 _stop_world_start = os::elapsedTime();
871 }
873 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
874 size_t start_used) {
875 if (PrintGCDetails) {
876 gclog_or_tty->stamp(PrintGCTimeStamps);
877 gclog_or_tty->print("[GC pause");
878 if (in_young_gc_mode())
879 gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
880 }
882 assert(_g1->used() == _g1->recalculate_used(),
883 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
884 _g1->used(), _g1->recalculate_used()));
886 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
887 _all_stop_world_times_ms->add(s_w_t_ms);
888 _stop_world_start = 0.0;
890 _cur_collection_start_sec = start_time_sec;
891 _cur_collection_pause_used_at_start_bytes = start_used;
892 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
893 _pending_cards = _g1->pending_card_num();
894 _max_pending_cards = _g1->max_pending_card_num();
896 _bytes_in_to_space_before_gc = 0;
897 _bytes_in_to_space_after_gc = 0;
898 _bytes_in_collection_set_before_gc = 0;
900 #ifdef DEBUG
901 // initialise these to something well known so that we can spot
902 // if they are not set properly
904 for (int i = 0; i < _parallel_gc_threads; ++i) {
905 _par_last_gc_worker_start_times_ms[i] = -1234.0;
906 _par_last_ext_root_scan_times_ms[i] = -1234.0;
907 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
908 _par_last_update_rs_times_ms[i] = -1234.0;
909 _par_last_update_rs_processed_buffers[i] = -1234.0;
910 _par_last_scan_rs_times_ms[i] = -1234.0;
911 _par_last_obj_copy_times_ms[i] = -1234.0;
912 _par_last_termination_times_ms[i] = -1234.0;
913 _par_last_termination_attempts[i] = -1234.0;
914 _par_last_gc_worker_end_times_ms[i] = -1234.0;
915 _par_last_gc_worker_times_ms[i] = -1234.0;
916 }
917 #endif
919 for (int i = 0; i < _aux_num; ++i) {
920 _cur_aux_times_ms[i] = 0.0;
921 _cur_aux_times_set[i] = false;
922 }
924 _satb_drain_time_set = false;
925 _last_satb_drain_processed_buffers = -1;
927 if (in_young_gc_mode())
928 _last_young_gc_full = false;
930 // do that for any other surv rate groups
931 _short_lived_surv_rate_group->stop_adding_regions();
932 _survivors_age_table.clear();
934 assert( verify_young_ages(), "region age verification" );
935 }
937 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
938 _mark_closure_time_ms = mark_closure_time_ms;
939 }
941 void G1CollectorPolicy::record_concurrent_mark_init_start() {
942 _mark_init_start_sec = os::elapsedTime();
943 guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
944 }
946 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
947 mark_init_elapsed_time_ms) {
948 _during_marking = true;
949 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
950 clear_during_initial_mark_pause();
951 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
952 }
954 void G1CollectorPolicy::record_concurrent_mark_init_end() {
955 double end_time_sec = os::elapsedTime();
956 double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
957 _concurrent_mark_init_times_ms->add(elapsed_time_ms);
958 record_concurrent_mark_init_end_pre(elapsed_time_ms);
960 _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
961 }
963 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
964 _mark_remark_start_sec = os::elapsedTime();
965 _during_marking = false;
966 }
968 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
969 double end_time_sec = os::elapsedTime();
970 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
971 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
972 _cur_mark_stop_world_time_ms += elapsed_time_ms;
973 _prev_collection_pause_end_ms += elapsed_time_ms;
975 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
976 }
978 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
979 _mark_cleanup_start_sec = os::elapsedTime();
980 }
982 void
983 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
984 size_t max_live_bytes) {
985 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
986 record_concurrent_mark_cleanup_end_work2();
987 }
989 void
990 G1CollectorPolicy::
991 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
992 size_t max_live_bytes) {
993 if (_n_marks < 2) _n_marks++;
994 if (G1PolicyVerbose > 0)
995 gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
996 " (of " SIZE_FORMAT " MB heap).",
997 max_live_bytes/M, _g1->capacity()/M);
998 }
1000 // The important thing about this is that it includes "os::elapsedTime".
1001 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
1002 double end_time_sec = os::elapsedTime();
1003 double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
1004 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1005 _cur_mark_stop_world_time_ms += elapsed_time_ms;
1006 _prev_collection_pause_end_ms += elapsed_time_ms;
1008 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
1010 _num_markings++;
1012 // We did a marking, so reset the "since_last_mark" variables.
1013 double considerConcMarkCost = 1.0;
1014 // If there are available processors, concurrent activity is free...
1015 if (Threads::number_of_non_daemon_threads() * 2 <
1016 os::active_processor_count()) {
1017 considerConcMarkCost = 0.0;
1018 }
1019 _n_pauses_at_mark_end = _n_pauses;
1020 _n_marks_since_last_pause++;
1021 }
1023 void
1024 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
1025 if (in_young_gc_mode()) {
1026 _should_revert_to_full_young_gcs = false;
1027 _last_full_young_gc = true;
1028 _in_marking_window = false;
1029 if (adaptive_young_list_length())
1030 calculate_young_list_target_length();
1031 }
1032 }
1034 void G1CollectorPolicy::record_concurrent_pause() {
1035 if (_stop_world_start > 0.0) {
1036 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
1037 _all_yield_times_ms->add(yield_ms);
1038 }
1039 }
1041 void G1CollectorPolicy::record_concurrent_pause_end() {
1042 }
1044 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
1045 _cur_CH_strong_roots_end_sec = os::elapsedTime();
1046 _cur_CH_strong_roots_dur_ms =
1047 (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
1048 }
1050 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
1051 _cur_G1_strong_roots_end_sec = os::elapsedTime();
1052 _cur_G1_strong_roots_dur_ms =
1053 (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
1054 }
1056 template<class T>
1057 T sum_of(T* sum_arr, int start, int n, int N) {
1058 T sum = (T)0;
1059 for (int i = 0; i < n; i++) {
1060 int j = (start + i) % N;
1061 sum += sum_arr[j];
1062 }
1063 return sum;
1064 }
1066 void G1CollectorPolicy::print_par_stats(int level,
1067 const char* str,
1068 double* data) {
1069 double min = data[0], max = data[0];
1070 double total = 0.0;
1071 LineBuffer buf(level);
1072 buf.append("[%s (ms):", str);
1073 for (uint i = 0; i < ParallelGCThreads; ++i) {
1074 double val = data[i];
1075 if (val < min)
1076 min = val;
1077 if (val > max)
1078 max = val;
1079 total += val;
1080 buf.append(" %3.1lf", val);
1081 }
1082 buf.append_and_print_cr("");
1083 double avg = total / (double) ParallelGCThreads;
1084 buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
1085 avg, min, max, max - min);
1086 }
1088 void G1CollectorPolicy::print_par_sizes(int level,
1089 const char* str,
1090 double* data) {
1091 double min = data[0], max = data[0];
1092 double total = 0.0;
1093 LineBuffer buf(level);
1094 buf.append("[%s :", str);
1095 for (uint i = 0; i < ParallelGCThreads; ++i) {
1096 double val = data[i];
1097 if (val < min)
1098 min = val;
1099 if (val > max)
1100 max = val;
1101 total += val;
1102 buf.append(" %d", (int) val);
1103 }
1104 buf.append_and_print_cr("");
1105 double avg = total / (double) ParallelGCThreads;
1106 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1107 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1108 }
1110 void G1CollectorPolicy::print_stats (int level,
1111 const char* str,
1112 double value) {
1113 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1114 }
1116 void G1CollectorPolicy::print_stats (int level,
1117 const char* str,
1118 int value) {
1119 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1120 }
1122 double G1CollectorPolicy::avg_value (double* data) {
1123 if (G1CollectedHeap::use_parallel_gc_threads()) {
1124 double ret = 0.0;
1125 for (uint i = 0; i < ParallelGCThreads; ++i)
1126 ret += data[i];
1127 return ret / (double) ParallelGCThreads;
1128 } else {
1129 return data[0];
1130 }
1131 }
1133 double G1CollectorPolicy::max_value (double* data) {
1134 if (G1CollectedHeap::use_parallel_gc_threads()) {
1135 double ret = data[0];
1136 for (uint i = 1; i < ParallelGCThreads; ++i)
1137 if (data[i] > ret)
1138 ret = data[i];
1139 return ret;
1140 } else {
1141 return data[0];
1142 }
1143 }
1145 double G1CollectorPolicy::sum_of_values (double* data) {
1146 if (G1CollectedHeap::use_parallel_gc_threads()) {
1147 double sum = 0.0;
1148 for (uint i = 0; i < ParallelGCThreads; i++)
1149 sum += data[i];
1150 return sum;
1151 } else {
1152 return data[0];
1153 }
1154 }
1156 double G1CollectorPolicy::max_sum (double* data1,
1157 double* data2) {
1158 double ret = data1[0] + data2[0];
1160 if (G1CollectedHeap::use_parallel_gc_threads()) {
1161 for (uint i = 1; i < ParallelGCThreads; ++i) {
1162 double data = data1[i] + data2[i];
1163 if (data > ret)
1164 ret = data;
1165 }
1166 }
1167 return ret;
1168 }
1170 // Anything below that is considered to be zero
1171 #define MIN_TIMER_GRANULARITY 0.0000001
1173 void G1CollectorPolicy::record_collection_pause_end() {
1174 double end_time_sec = os::elapsedTime();
1175 double elapsed_ms = _last_pause_time_ms;
1176 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1177 double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
1178 size_t rs_size =
1179 _cur_collection_pause_used_regions_at_start - collection_set_size();
1180 size_t cur_used_bytes = _g1->used();
1181 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1182 bool last_pause_included_initial_mark = false;
1183 bool update_stats = !_g1->evacuation_failed();
1185 #ifndef PRODUCT
1186 if (G1YoungSurvRateVerbose) {
1187 gclog_or_tty->print_cr("");
1188 _short_lived_surv_rate_group->print();
1189 // do that for any other surv rate groups too
1190 }
1191 #endif // PRODUCT
1193 if (in_young_gc_mode()) {
1194 last_pause_included_initial_mark = during_initial_mark_pause();
1195 if (last_pause_included_initial_mark)
1196 record_concurrent_mark_init_end_pre(0.0);
1198 size_t min_used_targ =
1199 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1202 if (!_g1->mark_in_progress() && !_last_full_young_gc) {
1203 assert(!last_pause_included_initial_mark, "invariant");
1204 if (cur_used_bytes > min_used_targ &&
1205 cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1206 assert(!during_initial_mark_pause(), "we should not see this here");
1208 // Note: this might have already been set, if during the last
1209 // pause we decided to start a cycle but at the beginning of
1210 // this pause we decided to postpone it. That's OK.
1211 set_initiate_conc_mark_if_possible();
1212 }
1213 }
1215 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1216 }
1218 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1219 end_time_sec, false);
1221 guarantee(_cur_collection_pause_used_regions_at_start >=
1222 collection_set_size(),
1223 "Negative RS size?");
1225 // This assert is exempted when we're doing parallel collection pauses,
1226 // because the fragmentation caused by the parallel GC allocation buffers
1227 // can lead to more memory being used during collection than was used
1228 // before. Best leave this out until the fragmentation problem is fixed.
1229 // Pauses in which evacuation failed can also lead to negative
1230 // collections, since no space is reclaimed from a region containing an
1231 // object whose evacuation failed.
1232 // Further, we're now always doing parallel collection. But I'm still
1233 // leaving this here as a placeholder for a more precise assertion later.
1234 // (DLD, 10/05.)
1235 assert((true || parallel) // Always using GC LABs now.
1236 || _g1->evacuation_failed()
1237 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1238 "Negative collection");
1240 size_t freed_bytes =
1241 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1242 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1244 double survival_fraction =
1245 (double)surviving_bytes/
1246 (double)_collection_set_bytes_used_before;
1248 _n_pauses++;
1250 if (update_stats) {
1251 _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
1252 _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
1253 _recent_evac_times_ms->add(evac_ms);
1254 _recent_pause_times_ms->add(elapsed_ms);
1256 _recent_rs_sizes->add(rs_size);
1258 // We exempt parallel collection from this check because Alloc Buffer
1259 // fragmentation can produce negative collections. Same with evac
1260 // failure.
1261 // Further, we're now always doing parallel collection. But I'm still
1262 // leaving this here as a placeholder for a more precise assertion later.
1263 // (DLD, 10/05.
1264 assert((true || parallel)
1265 || _g1->evacuation_failed()
1266 || surviving_bytes <= _collection_set_bytes_used_before,
1267 "Or else negative collection!");
1268 _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
1269 _recent_CS_bytes_surviving->add(surviving_bytes);
1271 // this is where we update the allocation rate of the application
1272 double app_time_ms =
1273 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1274 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1275 // This usually happens due to the timer not having the required
1276 // granularity. Some Linuxes are the usual culprits.
1277 // We'll just set it to something (arbitrarily) small.
1278 app_time_ms = 1.0;
1279 }
1280 size_t regions_allocated =
1281 (_region_num_young - _prev_region_num_young) +
1282 (_region_num_tenured - _prev_region_num_tenured);
1283 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1284 _alloc_rate_ms_seq->add(alloc_rate_ms);
1285 _prev_region_num_young = _region_num_young;
1286 _prev_region_num_tenured = _region_num_tenured;
1288 double interval_ms =
1289 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1290 update_recent_gc_times(end_time_sec, elapsed_ms);
1291 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1292 if (recent_avg_pause_time_ratio() < 0.0 ||
1293 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1294 #ifndef PRODUCT
1295 // Dump info to allow post-facto debugging
1296 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1297 gclog_or_tty->print_cr("-------------------------------------------");
1298 gclog_or_tty->print_cr("Recent GC Times (ms):");
1299 _recent_gc_times_ms->dump();
1300 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1301 _recent_prev_end_times_for_all_gcs_sec->dump();
1302 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1303 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1304 // In debug mode, terminate the JVM if the user wants to debug at this point.
1305 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1306 #endif // !PRODUCT
1307 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1308 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1309 if (_recent_avg_pause_time_ratio < 0.0) {
1310 _recent_avg_pause_time_ratio = 0.0;
1311 } else {
1312 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1313 _recent_avg_pause_time_ratio = 1.0;
1314 }
1315 }
1316 }
1318 if (G1PolicyVerbose > 1) {
1319 gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
1320 }
1322 PauseSummary* summary = _summary;
1324 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1325 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1326 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1327 double update_rs_processed_buffers =
1328 sum_of_values(_par_last_update_rs_processed_buffers);
1329 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1330 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1331 double termination_time = avg_value(_par_last_termination_times_ms);
1333 double parallel_other_time = _cur_collection_par_time_ms -
1334 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
1335 scan_rs_time + obj_copy_time + termination_time);
1336 if (update_stats) {
1337 MainBodySummary* body_summary = summary->main_body_summary();
1338 guarantee(body_summary != NULL, "should not be null!");
1340 if (_satb_drain_time_set)
1341 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1342 else
1343 body_summary->record_satb_drain_time_ms(0.0);
1344 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1345 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1346 body_summary->record_update_rs_time_ms(update_rs_time);
1347 body_summary->record_scan_rs_time_ms(scan_rs_time);
1348 body_summary->record_obj_copy_time_ms(obj_copy_time);
1349 if (parallel) {
1350 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1351 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1352 body_summary->record_termination_time_ms(termination_time);
1353 body_summary->record_parallel_other_time_ms(parallel_other_time);
1354 }
1355 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1356 }
1358 if (G1PolicyVerbose > 1) {
1359 gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
1360 " CH Strong: %10.6f ms (avg: %10.6f ms)\n"
1361 " G1 Strong: %10.6f ms (avg: %10.6f ms)\n"
1362 " Evac: %10.6f ms (avg: %10.6f ms)\n"
1363 " ET-RS: %10.6f ms (avg: %10.6f ms)\n"
1364 " |RS|: " SIZE_FORMAT,
1365 elapsed_ms, recent_avg_time_for_pauses_ms(),
1366 _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
1367 _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
1368 evac_ms, recent_avg_time_for_evac_ms(),
1369 scan_rs_time,
1370 recent_avg_time_for_pauses_ms() -
1371 recent_avg_time_for_G1_strong_ms(),
1372 rs_size);
1374 gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
1375 " At end " SIZE_FORMAT "K\n"
1376 " garbage : " SIZE_FORMAT "K"
1377 " of " SIZE_FORMAT "K\n"
1378 " survival : %6.2f%% (%6.2f%% avg)",
1379 _cur_collection_pause_used_at_start_bytes/K,
1380 _g1->used()/K, freed_bytes/K,
1381 _collection_set_bytes_used_before/K,
1382 survival_fraction*100.0,
1383 recent_avg_survival_fraction()*100.0);
1384 gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
1385 recent_avg_pause_time_ratio() * 100.0);
1386 }
1388 double other_time_ms = elapsed_ms;
1390 if (_satb_drain_time_set) {
1391 other_time_ms -= _cur_satb_drain_time_ms;
1392 }
1394 if (parallel) {
1395 other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
1396 } else {
1397 other_time_ms -=
1398 update_rs_time +
1399 ext_root_scan_time + mark_stack_scan_time +
1400 scan_rs_time + obj_copy_time;
1401 }
1403 if (PrintGCDetails) {
1404 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1405 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1406 elapsed_ms / 1000.0);
1408 if (_satb_drain_time_set) {
1409 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1410 }
1411 if (_last_satb_drain_processed_buffers >= 0) {
1412 print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
1413 }
1414 if (parallel) {
1415 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1416 print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
1417 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1418 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1419 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1420 print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
1421 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1422 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1423 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1424 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1425 print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);
1427 for (int i = 0; i < _parallel_gc_threads; i++) {
1428 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
1429 }
1430 print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);
1432 print_stats(2, "Other", parallel_other_time);
1433 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1434 } else {
1435 print_stats(1, "Update RS", update_rs_time);
1436 print_stats(2, "Processed Buffers",
1437 (int)update_rs_processed_buffers);
1438 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1439 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1440 print_stats(1, "Scan RS", scan_rs_time);
1441 print_stats(1, "Object Copying", obj_copy_time);
1442 }
1443 #ifndef PRODUCT
1444 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1445 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1446 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1447 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1448 if (_num_cc_clears > 0) {
1449 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1450 }
1451 #endif
1452 print_stats(1, "Other", other_time_ms);
1453 print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
1455 for (int i = 0; i < _aux_num; ++i) {
1456 if (_cur_aux_times_set[i]) {
1457 char buffer[96];
1458 sprintf(buffer, "Aux%d", i);
1459 print_stats(1, buffer, _cur_aux_times_ms[i]);
1460 }
1461 }
1462 }
1463 if (PrintGCDetails)
1464 gclog_or_tty->print(" [");
1465 if (PrintGC || PrintGCDetails)
1466 _g1->print_size_transition(gclog_or_tty,
1467 _cur_collection_pause_used_at_start_bytes,
1468 _g1->used(), _g1->capacity());
1469 if (PrintGCDetails)
1470 gclog_or_tty->print_cr("]");
1472 _all_pause_times_ms->add(elapsed_ms);
1473 if (update_stats) {
1474 summary->record_total_time_ms(elapsed_ms);
1475 summary->record_other_time_ms(other_time_ms);
1476 }
1477 for (int i = 0; i < _aux_num; ++i)
1478 if (_cur_aux_times_set[i])
1479 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1481 // Reset marks-between-pauses counter.
1482 _n_marks_since_last_pause = 0;
1484 // Update the efficiency-since-mark vars.
1485 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1486 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1487 // This usually happens due to the timer not having the required
1488 // granularity. Some Linuxes are the usual culprits.
1489 // We'll just set it to something (arbitrarily) small.
1490 proc_ms = 1.0;
1491 }
1492 double cur_efficiency = (double) freed_bytes / proc_ms;
1494 bool new_in_marking_window = _in_marking_window;
1495 bool new_in_marking_window_im = false;
1496 if (during_initial_mark_pause()) {
1497 new_in_marking_window = true;
1498 new_in_marking_window_im = true;
1499 }
1501 if (in_young_gc_mode()) {
1502 if (_last_full_young_gc) {
1503 set_full_young_gcs(false);
1504 _last_full_young_gc = false;
1505 }
1507 if ( !_last_young_gc_full ) {
1508 if ( _should_revert_to_full_young_gcs ||
1509 _known_garbage_ratio < 0.05 ||
1510 (adaptive_young_list_length() &&
1511 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
1512 set_full_young_gcs(true);
1513 }
1514 }
1515 _should_revert_to_full_young_gcs = false;
1517 if (_last_young_gc_full && !_during_marking)
1518 _young_gc_eff_seq->add(cur_efficiency);
1519 }
1521 _short_lived_surv_rate_group->start_adding_regions();
1522 // do that for any other surv rate groupsx
1524 // <NEW PREDICTION>
1526 if (update_stats) {
1527 double pause_time_ms = elapsed_ms;
1529 size_t diff = 0;
1530 if (_max_pending_cards >= _pending_cards)
1531 diff = _max_pending_cards - _pending_cards;
1532 _pending_card_diff_seq->add((double) diff);
1534 double cost_per_card_ms = 0.0;
1535 if (_pending_cards > 0) {
1536 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1537 _cost_per_card_ms_seq->add(cost_per_card_ms);
1538 }
1540 size_t cards_scanned = _g1->cards_scanned();
1542 double cost_per_entry_ms = 0.0;
1543 if (cards_scanned > 10) {
1544 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1545 if (_last_young_gc_full)
1546 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1547 else
1548 _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1549 }
1551 if (_max_rs_lengths > 0) {
1552 double cards_per_entry_ratio =
1553 (double) cards_scanned / (double) _max_rs_lengths;
1554 if (_last_young_gc_full)
1555 _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1556 else
1557 _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1558 }
1560 size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1561 if (rs_length_diff >= 0)
1562 _rs_length_diff_seq->add((double) rs_length_diff);
1564 size_t copied_bytes = surviving_bytes;
1565 double cost_per_byte_ms = 0.0;
1566 if (copied_bytes > 0) {
1567 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1568 if (_in_marking_window)
1569 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1570 else
1571 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1572 }
1574 double all_other_time_ms = pause_time_ms -
1575 (update_rs_time + scan_rs_time + obj_copy_time +
1576 _mark_closure_time_ms + termination_time);
1578 double young_other_time_ms = 0.0;
1579 if (_recorded_young_regions > 0) {
1580 young_other_time_ms =
1581 _recorded_young_cset_choice_time_ms +
1582 _recorded_young_free_cset_time_ms;
1583 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1584 (double) _recorded_young_regions);
1585 }
1586 double non_young_other_time_ms = 0.0;
1587 if (_recorded_non_young_regions > 0) {
1588 non_young_other_time_ms =
1589 _recorded_non_young_cset_choice_time_ms +
1590 _recorded_non_young_free_cset_time_ms;
1592 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1593 (double) _recorded_non_young_regions);
1594 }
1596 double constant_other_time_ms = all_other_time_ms -
1597 (young_other_time_ms + non_young_other_time_ms);
1598 _constant_other_time_ms_seq->add(constant_other_time_ms);
1600 double survival_ratio = 0.0;
1601 if (_bytes_in_collection_set_before_gc > 0) {
1602 survival_ratio = (double) bytes_in_to_space_during_gc() /
1603 (double) _bytes_in_collection_set_before_gc;
1604 }
1606 _pending_cards_seq->add((double) _pending_cards);
1607 _scanned_cards_seq->add((double) cards_scanned);
1608 _rs_lengths_seq->add((double) _max_rs_lengths);
1610 double expensive_region_limit_ms =
1611 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1612 if (expensive_region_limit_ms < 0.0) {
1613 // this means that the other time was predicted to be longer than
1614 // than the max pause time
1615 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1616 }
1617 _expensive_region_limit_ms = expensive_region_limit_ms;
1619 if (PREDICTIONS_VERBOSE) {
1620 gclog_or_tty->print_cr("");
1621 gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
1622 "REGIONS %d %d %d "
1623 "PENDING_CARDS %d %d "
1624 "CARDS_SCANNED %d %d "
1625 "RS_LENGTHS %d %d "
1626 "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
1627 "SURVIVAL_RATIO %1.6lf %1.6lf "
1628 "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
1629 "OTHER_YOUNG %1.6lf %1.6lf "
1630 "OTHER_NON_YOUNG %1.6lf %1.6lf "
1631 "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
1632 "ELAPSED %1.6lf %1.6lf ",
1633 _cur_collection_start_sec,
1634 (!_last_young_gc_full) ? 2 :
1635 (last_pause_included_initial_mark) ? 1 : 0,
1636 _recorded_region_num,
1637 _recorded_young_regions,
1638 _recorded_non_young_regions,
1639 _predicted_pending_cards, _pending_cards,
1640 _predicted_cards_scanned, cards_scanned,
1641 _predicted_rs_lengths, _max_rs_lengths,
1642 _predicted_rs_update_time_ms, update_rs_time,
1643 _predicted_rs_scan_time_ms, scan_rs_time,
1644 _predicted_survival_ratio, survival_ratio,
1645 _predicted_object_copy_time_ms, obj_copy_time,
1646 _predicted_constant_other_time_ms, constant_other_time_ms,
1647 _predicted_young_other_time_ms, young_other_time_ms,
1648 _predicted_non_young_other_time_ms,
1649 non_young_other_time_ms,
1650 _vtime_diff_ms, termination_time,
1651 _predicted_pause_time_ms, elapsed_ms);
1652 }
1654 if (G1PolicyVerbose > 0) {
1655 gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
1656 _predicted_pause_time_ms,
1657 (_within_target) ? "within" : "outside",
1658 elapsed_ms);
1659 }
1661 }
1663 _in_marking_window = new_in_marking_window;
1664 _in_marking_window_im = new_in_marking_window_im;
1665 _free_regions_at_end_of_collection = _g1->free_regions();
1666 calculate_young_list_min_length();
1667 calculate_young_list_target_length();
1669 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1670 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1671 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1672 // </NEW PREDICTION>
1673 }
1675 // <NEW PREDICTION>
1677 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1678 double update_rs_processed_buffers,
1679 double goal_ms) {
1680 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1681 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1683 if (G1UseAdaptiveConcRefinement) {
1684 const int k_gy = 3, k_gr = 6;
1685 const double inc_k = 1.1, dec_k = 0.9;
1687 int g = cg1r->green_zone();
1688 if (update_rs_time > goal_ms) {
1689 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1690 } else {
1691 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1692 g = (int)MAX2(g * inc_k, g + 1.0);
1693 }
1694 }
1695 // Change the refinement threads params
1696 cg1r->set_green_zone(g);
1697 cg1r->set_yellow_zone(g * k_gy);
1698 cg1r->set_red_zone(g * k_gr);
1699 cg1r->reinitialize_threads();
1701 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1702 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1703 cg1r->yellow_zone());
1704 // Change the barrier params
1705 dcqs.set_process_completed_threshold(processing_threshold);
1706 dcqs.set_max_completed_queue(cg1r->red_zone());
1707 }
1709 int curr_queue_size = dcqs.completed_buffers_num();
1710 if (curr_queue_size >= cg1r->yellow_zone()) {
1711 dcqs.set_completed_queue_padding(curr_queue_size);
1712 } else {
1713 dcqs.set_completed_queue_padding(0);
1714 }
1715 dcqs.notify_if_necessary();
1716 }
1718 double
1719 G1CollectorPolicy::
1720 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1721 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1723 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1724 size_t young_num = g1h->young_list()->length();
1725 if (young_num == 0)
1726 return 0.0;
1728 young_num += adjustment;
1729 size_t pending_cards = predict_pending_cards();
1730 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1731 predict_rs_length_diff();
1732 size_t card_num;
1733 if (full_young_gcs())
1734 card_num = predict_young_card_num(rs_lengths);
1735 else
1736 card_num = predict_non_young_card_num(rs_lengths);
1737 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1738 double accum_yg_surv_rate =
1739 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1741 size_t bytes_to_copy =
1742 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1744 return
1745 predict_rs_update_time_ms(pending_cards) +
1746 predict_rs_scan_time_ms(card_num) +
1747 predict_object_copy_time_ms(bytes_to_copy) +
1748 predict_young_other_time_ms(young_num) +
1749 predict_constant_other_time_ms();
1750 }
1752 double
1753 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1754 size_t rs_length = predict_rs_length_diff();
1755 size_t card_num;
1756 if (full_young_gcs())
1757 card_num = predict_young_card_num(rs_length);
1758 else
1759 card_num = predict_non_young_card_num(rs_length);
1760 return predict_base_elapsed_time_ms(pending_cards, card_num);
1761 }
1763 double
1764 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1765 size_t scanned_cards) {
1766 return
1767 predict_rs_update_time_ms(pending_cards) +
1768 predict_rs_scan_time_ms(scanned_cards) +
1769 predict_constant_other_time_ms();
1770 }
1772 double
1773 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1774 bool young) {
1775 size_t rs_length = hr->rem_set()->occupied();
1776 size_t card_num;
1777 if (full_young_gcs())
1778 card_num = predict_young_card_num(rs_length);
1779 else
1780 card_num = predict_non_young_card_num(rs_length);
1781 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1783 double region_elapsed_time_ms =
1784 predict_rs_scan_time_ms(card_num) +
1785 predict_object_copy_time_ms(bytes_to_copy);
1787 if (young)
1788 region_elapsed_time_ms += predict_young_other_time_ms(1);
1789 else
1790 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1792 return region_elapsed_time_ms;
1793 }
1795 size_t
1796 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1797 size_t bytes_to_copy;
1798 if (hr->is_marked())
1799 bytes_to_copy = hr->max_live_bytes();
1800 else {
1801 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1802 "invariant" );
1803 int age = hr->age_in_surv_rate_group();
1804 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1805 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1806 }
1808 return bytes_to_copy;
1809 }
1811 void
1812 G1CollectorPolicy::start_recording_regions() {
1813 _recorded_rs_lengths = 0;
1814 _recorded_young_regions = 0;
1815 _recorded_non_young_regions = 0;
1817 #if PREDICTIONS_VERBOSE
1818 _recorded_marked_bytes = 0;
1819 _recorded_young_bytes = 0;
1820 _predicted_bytes_to_copy = 0;
1821 _predicted_rs_lengths = 0;
1822 _predicted_cards_scanned = 0;
1823 #endif // PREDICTIONS_VERBOSE
1824 }
1826 void
1827 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
1828 #if PREDICTIONS_VERBOSE
1829 if (!young) {
1830 _recorded_marked_bytes += hr->max_live_bytes();
1831 }
1832 _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
1833 #endif // PREDICTIONS_VERBOSE
1835 size_t rs_length = hr->rem_set()->occupied();
1836 _recorded_rs_lengths += rs_length;
1837 }
1839 void
1840 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
1841 assert(!hr->is_young(), "should not call this");
1842 ++_recorded_non_young_regions;
1843 record_cset_region_info(hr, false);
1844 }
1846 void
1847 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
1848 _recorded_young_regions = n_regions;
1849 }
1851 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
1852 #if PREDICTIONS_VERBOSE
1853 _recorded_young_bytes = bytes;
1854 #endif // PREDICTIONS_VERBOSE
1855 }
1857 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1858 _recorded_rs_lengths = rs_lengths;
1859 }
1861 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
1862 _predicted_bytes_to_copy = bytes;
1863 }
1865 void
1866 G1CollectorPolicy::end_recording_regions() {
1867 // The _predicted_pause_time_ms field is referenced in code
1868 // not under PREDICTIONS_VERBOSE. Let's initialize it.
1869 _predicted_pause_time_ms = -1.0;
1871 #if PREDICTIONS_VERBOSE
1872 _predicted_pending_cards = predict_pending_cards();
1873 _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
1874 if (full_young_gcs())
1875 _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
1876 else
1877 _predicted_cards_scanned +=
1878 predict_non_young_card_num(_predicted_rs_lengths);
1879 _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
1881 _predicted_rs_update_time_ms =
1882 predict_rs_update_time_ms(_g1->pending_card_num());
1883 _predicted_rs_scan_time_ms =
1884 predict_rs_scan_time_ms(_predicted_cards_scanned);
1885 _predicted_object_copy_time_ms =
1886 predict_object_copy_time_ms(_predicted_bytes_to_copy);
1887 _predicted_constant_other_time_ms =
1888 predict_constant_other_time_ms();
1889 _predicted_young_other_time_ms =
1890 predict_young_other_time_ms(_recorded_young_regions);
1891 _predicted_non_young_other_time_ms =
1892 predict_non_young_other_time_ms(_recorded_non_young_regions);
1894 _predicted_pause_time_ms =
1895 _predicted_rs_update_time_ms +
1896 _predicted_rs_scan_time_ms +
1897 _predicted_object_copy_time_ms +
1898 _predicted_constant_other_time_ms +
1899 _predicted_young_other_time_ms +
1900 _predicted_non_young_other_time_ms;
1901 #endif // PREDICTIONS_VERBOSE
1902 }
1904 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1905 predicted_time_ms) {
1906 // I don't think we need to do this when in young GC mode since
1907 // marking will be initiated next time we hit the soft limit anyway...
1908 if (predicted_time_ms > _expensive_region_limit_ms) {
1909 if (!in_young_gc_mode()) {
1910 set_full_young_gcs(true);
1911 // We might want to do something different here. However,
1912 // right now we don't support the non-generational G1 mode
1913 // (and in fact we are planning to remove the associated code,
1914 // see CR 6814390). So, let's leave it as is and this will be
1915 // removed some time in the future
1916 ShouldNotReachHere();
1917 set_during_initial_mark_pause();
1918 } else
1919 // no point in doing another partial one
1920 _should_revert_to_full_young_gcs = true;
1921 }
1922 }
1924 // </NEW PREDICTION>
1927 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1928 double elapsed_ms) {
1929 _recent_gc_times_ms->add(elapsed_ms);
1930 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1931 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1932 }
1934 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
1935 if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
1936 else return _recent_pause_times_ms->avg();
1937 }
1939 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
1940 if (_recent_CH_strong_roots_times_ms->num() == 0)
1941 return (double)MaxGCPauseMillis/3.0;
1942 else return _recent_CH_strong_roots_times_ms->avg();
1943 }
1945 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
1946 if (_recent_G1_strong_roots_times_ms->num() == 0)
1947 return (double)MaxGCPauseMillis/3.0;
1948 else return _recent_G1_strong_roots_times_ms->avg();
1949 }
1951 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
1952 if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
1953 else return _recent_evac_times_ms->avg();
1954 }
1956 int G1CollectorPolicy::number_of_recent_gcs() {
1957 assert(_recent_CH_strong_roots_times_ms->num() ==
1958 _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
1959 assert(_recent_G1_strong_roots_times_ms->num() ==
1960 _recent_evac_times_ms->num(), "Sequence out of sync");
1961 assert(_recent_evac_times_ms->num() ==
1962 _recent_pause_times_ms->num(), "Sequence out of sync");
1963 assert(_recent_pause_times_ms->num() ==
1964 _recent_CS_bytes_used_before->num(), "Sequence out of sync");
1965 assert(_recent_CS_bytes_used_before->num() ==
1966 _recent_CS_bytes_surviving->num(), "Sequence out of sync");
1967 return _recent_pause_times_ms->num();
1968 }
1970 double G1CollectorPolicy::recent_avg_survival_fraction() {
1971 return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
1972 _recent_CS_bytes_used_before);
1973 }
1975 double G1CollectorPolicy::last_survival_fraction() {
1976 return last_survival_fraction_work(_recent_CS_bytes_surviving,
1977 _recent_CS_bytes_used_before);
1978 }
1980 double
1981 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
1982 TruncatedSeq* before) {
1983 assert(surviving->num() == before->num(), "Sequence out of sync");
1984 if (before->sum() > 0.0) {
1985 double recent_survival_rate = surviving->sum() / before->sum();
1986 // We exempt parallel collection from this check because Alloc Buffer
1987 // fragmentation can produce negative collections.
1988 // Further, we're now always doing parallel collection. But I'm still
1989 // leaving this here as a placeholder for a more precise assertion later.
1990 // (DLD, 10/05.)
1991 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
1992 _g1->evacuation_failed() ||
1993 recent_survival_rate <= 1.0, "Or bad frac");
1994 return recent_survival_rate;
1995 } else {
1996 return 1.0; // Be conservative.
1997 }
1998 }
2000 double
2001 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
2002 TruncatedSeq* before) {
2003 assert(surviving->num() == before->num(), "Sequence out of sync");
2004 if (surviving->num() > 0 && before->last() > 0.0) {
2005 double last_survival_rate = surviving->last() / before->last();
2006 // We exempt parallel collection from this check because Alloc Buffer
2007 // fragmentation can produce negative collections.
2008 // Further, we're now always doing parallel collection. But I'm still
2009 // leaving this here as a placeholder for a more precise assertion later.
2010 // (DLD, 10/05.)
2011 assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
2012 last_survival_rate <= 1.0, "Or bad frac");
2013 return last_survival_rate;
2014 } else {
2015 return 1.0;
2016 }
2017 }
2019 static const int survival_min_obs = 5;
2020 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
2021 static const double min_survival_rate = 0.1;
2023 double
2024 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
2025 double latest) {
2026 double res = avg;
2027 if (number_of_recent_gcs() < survival_min_obs) {
2028 res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
2029 }
2030 res = MAX2(res, latest);
2031 res = MAX2(res, min_survival_rate);
2032 // In the parallel case, LAB fragmentation can produce "negative
2033 // collections"; so can evac failure. Cap at 1.0
2034 res = MIN2(res, 1.0);
2035 return res;
2036 }
2038 size_t G1CollectorPolicy::expansion_amount() {
2039 if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
2040 // We will double the existing space, or take
2041 // G1ExpandByPercentOfAvailable % of the available expansion
2042 // space, whichever is smaller, bounded below by a minimum
2043 // expansion (unless that's all that's left.)
2044 const size_t min_expand_bytes = 1*M;
2045 size_t reserved_bytes = _g1->max_capacity();
2046 size_t committed_bytes = _g1->capacity();
2047 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
2048 size_t expand_bytes;
2049 size_t expand_bytes_via_pct =
2050 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
2051 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
2052 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
2053 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
2054 if (G1PolicyVerbose > 1) {
2055 gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
2056 "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
2057 " Answer = %d.\n",
2058 recent_avg_pause_time_ratio(),
2059 byte_size_in_proper_unit(committed_bytes),
2060 proper_unit_for_byte_size(committed_bytes),
2061 byte_size_in_proper_unit(uncommitted_bytes),
2062 proper_unit_for_byte_size(uncommitted_bytes),
2063 byte_size_in_proper_unit(expand_bytes_via_pct),
2064 proper_unit_for_byte_size(expand_bytes_via_pct),
2065 byte_size_in_proper_unit(expand_bytes),
2066 proper_unit_for_byte_size(expand_bytes));
2067 }
2068 return expand_bytes;
2069 } else {
2070 return 0;
2071 }
2072 }
2074 void G1CollectorPolicy::note_start_of_mark_thread() {
2075 _mark_thread_startup_sec = os::elapsedTime();
2076 }
2078 class CountCSClosure: public HeapRegionClosure {
2079 G1CollectorPolicy* _g1_policy;
2080 public:
2081 CountCSClosure(G1CollectorPolicy* g1_policy) :
2082 _g1_policy(g1_policy) {}
2083 bool doHeapRegion(HeapRegion* r) {
2084 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
2085 return false;
2086 }
2087 };
2089 void G1CollectorPolicy::count_CS_bytes_used() {
2090 CountCSClosure cs_closure(this);
2091 _g1->collection_set_iterate(&cs_closure);
2092 }
2094 void G1CollectorPolicy::print_summary (int level,
2095 const char* str,
2096 NumberSeq* seq) const {
2097 double sum = seq->sum();
2098 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2099 str, sum / 1000.0, seq->avg());
2100 }
2102 void G1CollectorPolicy::print_summary_sd (int level,
2103 const char* str,
2104 NumberSeq* seq) const {
2105 print_summary(level, str, seq);
2106 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2107 seq->num(), seq->sd(), seq->maximum());
2108 }
2110 void G1CollectorPolicy::check_other_times(int level,
2111 NumberSeq* other_times_ms,
2112 NumberSeq* calc_other_times_ms) const {
2113 bool should_print = false;
2114 LineBuffer buf(level + 2);
2116 double max_sum = MAX2(fabs(other_times_ms->sum()),
2117 fabs(calc_other_times_ms->sum()));
2118 double min_sum = MIN2(fabs(other_times_ms->sum()),
2119 fabs(calc_other_times_ms->sum()));
2120 double sum_ratio = max_sum / min_sum;
2121 if (sum_ratio > 1.1) {
2122 should_print = true;
2123 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
2124 }
2126 double max_avg = MAX2(fabs(other_times_ms->avg()),
2127 fabs(calc_other_times_ms->avg()));
2128 double min_avg = MIN2(fabs(other_times_ms->avg()),
2129 fabs(calc_other_times_ms->avg()));
2130 double avg_ratio = max_avg / min_avg;
2131 if (avg_ratio > 1.1) {
2132 should_print = true;
2133 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
2134 }
2136 if (other_times_ms->sum() < -0.01) {
2137 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
2138 }
2140 if (other_times_ms->avg() < -0.01) {
2141 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
2142 }
2144 if (calc_other_times_ms->sum() < -0.01) {
2145 should_print = true;
2146 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
2147 }
2149 if (calc_other_times_ms->avg() < -0.01) {
2150 should_print = true;
2151 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
2152 }
2154 if (should_print)
2155 print_summary(level, "Other(Calc)", calc_other_times_ms);
2156 }
2158 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
2159 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
2160 MainBodySummary* body_summary = summary->main_body_summary();
2161 if (summary->get_total_seq()->num() > 0) {
2162 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
2163 if (body_summary != NULL) {
2164 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
2165 if (parallel) {
2166 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
2167 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
2168 print_summary(2, "Ext Root Scanning",
2169 body_summary->get_ext_root_scan_seq());
2170 print_summary(2, "Mark Stack Scanning",
2171 body_summary->get_mark_stack_scan_seq());
2172 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
2173 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
2174 print_summary(2, "Termination", body_summary->get_termination_seq());
2175 print_summary(2, "Other", body_summary->get_parallel_other_seq());
2176 {
2177 NumberSeq* other_parts[] = {
2178 body_summary->get_update_rs_seq(),
2179 body_summary->get_ext_root_scan_seq(),
2180 body_summary->get_mark_stack_scan_seq(),
2181 body_summary->get_scan_rs_seq(),
2182 body_summary->get_obj_copy_seq(),
2183 body_summary->get_termination_seq()
2184 };
2185 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
2186 6, other_parts);
2187 check_other_times(2, body_summary->get_parallel_other_seq(),
2188 &calc_other_times_ms);
2189 }
2190 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2191 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2192 } else {
2193 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
2194 print_summary(1, "Ext Root Scanning",
2195 body_summary->get_ext_root_scan_seq());
2196 print_summary(1, "Mark Stack Scanning",
2197 body_summary->get_mark_stack_scan_seq());
2198 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
2199 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
2200 }
2201 }
2202 print_summary(1, "Other", summary->get_other_seq());
2203 {
2204 if (body_summary != NULL) {
2205 NumberSeq calc_other_times_ms;
2206 if (parallel) {
2207 // parallel
2208 NumberSeq* other_parts[] = {
2209 body_summary->get_satb_drain_seq(),
2210 body_summary->get_parallel_seq(),
2211 body_summary->get_clear_ct_seq()
2212 };
2213 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2214 3, other_parts);
2215 } else {
2216 // serial
2217 NumberSeq* other_parts[] = {
2218 body_summary->get_satb_drain_seq(),
2219 body_summary->get_update_rs_seq(),
2220 body_summary->get_ext_root_scan_seq(),
2221 body_summary->get_mark_stack_scan_seq(),
2222 body_summary->get_scan_rs_seq(),
2223 body_summary->get_obj_copy_seq()
2224 };
2225 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2226 6, other_parts);
2227 }
2228 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2229 }
2230 }
2231 } else {
2232 LineBuffer(1).append_and_print_cr("none");
2233 }
2234 LineBuffer(0).append_and_print_cr("");
2235 }
2237 void G1CollectorPolicy::print_tracing_info() const {
2238 if (TraceGen0Time) {
2239 gclog_or_tty->print_cr("ALL PAUSES");
2240 print_summary_sd(0, "Total", _all_pause_times_ms);
2241 gclog_or_tty->print_cr("");
2242 gclog_or_tty->print_cr("");
2243 gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
2244 gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
2245 gclog_or_tty->print_cr("");
2247 gclog_or_tty->print_cr("EVACUATION PAUSES");
2248 print_summary(_summary);
2250 gclog_or_tty->print_cr("MISC");
2251 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2252 print_summary_sd(0, "Yields", _all_yield_times_ms);
2253 for (int i = 0; i < _aux_num; ++i) {
2254 if (_all_aux_times_ms[i].num() > 0) {
2255 char buffer[96];
2256 sprintf(buffer, "Aux%d", i);
2257 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2258 }
2259 }
2261 size_t all_region_num = _region_num_young + _region_num_tenured;
2262 gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
2263 "Tenured %8d (%6.2lf%%)",
2264 all_region_num,
2265 _region_num_young,
2266 (double) _region_num_young / (double) all_region_num * 100.0,
2267 _region_num_tenured,
2268 (double) _region_num_tenured / (double) all_region_num * 100.0);
2269 }
2270 if (TraceGen1Time) {
2271 if (_all_full_gc_times_ms->num() > 0) {
2272 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2273 _all_full_gc_times_ms->num(),
2274 _all_full_gc_times_ms->sum() / 1000.0);
2275 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2276 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2277 _all_full_gc_times_ms->sd(),
2278 _all_full_gc_times_ms->maximum());
2279 }
2280 }
2281 }
2283 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2284 #ifndef PRODUCT
2285 _short_lived_surv_rate_group->print_surv_rate_summary();
2286 // add this call for any other surv rate groups
2287 #endif // PRODUCT
2288 }
2290 void
2291 G1CollectorPolicy::update_region_num(bool young) {
2292 if (young) {
2293 ++_region_num_young;
2294 } else {
2295 ++_region_num_tenured;
2296 }
2297 }
2299 #ifndef PRODUCT
2300 // for debugging, bit of a hack...
2301 static char*
2302 region_num_to_mbs(int length) {
2303 static char buffer[64];
2304 double bytes = (double) (length * HeapRegion::GrainBytes);
2305 double mbs = bytes / (double) (1024 * 1024);
2306 sprintf(buffer, "%7.2lfMB", mbs);
2307 return buffer;
2308 }
2309 #endif // PRODUCT
2311 size_t G1CollectorPolicy::max_regions(int purpose) {
2312 switch (purpose) {
2313 case GCAllocForSurvived:
2314 return _max_survivor_regions;
2315 case GCAllocForTenured:
2316 return REGIONS_UNLIMITED;
2317 default:
2318 ShouldNotReachHere();
2319 return REGIONS_UNLIMITED;
2320 };
2321 }
2323 void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
2324 size_t expansion_region_num = 0;
2325 if (GCLockerEdenExpansionPercent > 0) {
2326 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2327 double expansion_region_num_d = perc * (double) _young_list_target_length;
2328 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2329 // less than 1.0) we'll get 1.
2330 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2331 } else {
2332 assert(expansion_region_num == 0, "sanity");
2333 }
2334 _young_list_max_length = _young_list_target_length + expansion_region_num;
2335 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2336 }
2338 // Calculates survivor space parameters.
2339 void G1CollectorPolicy::calculate_survivors_policy()
2340 {
2341 if (G1FixedSurvivorSpaceSize == 0) {
2342 _max_survivor_regions = _young_list_target_length / SurvivorRatio;
2343 } else {
2344 _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
2345 }
2347 if (G1FixedTenuringThreshold) {
2348 _tenuring_threshold = MaxTenuringThreshold;
2349 } else {
2350 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2351 HeapRegion::GrainWords * _max_survivor_regions);
2352 }
2353 }
2355 #ifndef PRODUCT
2356 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2357 CollectionSetChooser* _chooser;
2358 public:
2359 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2360 _chooser(chooser) {}
2362 bool doHeapRegion(HeapRegion* r) {
2363 if (!r->continuesHumongous()) {
2364 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2365 }
2366 return false;
2367 }
2368 };
2370 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
2371 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2372 _g1->heap_region_iterate(&cl);
2373 return true;
2374 }
2375 #endif
2377 bool
2378 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
2379 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2380 if (!during_cycle) {
2381 set_initiate_conc_mark_if_possible();
2382 return true;
2383 } else {
2384 return false;
2385 }
2386 }
2388 void
2389 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2390 // We are about to decide on whether this pause will be an
2391 // initial-mark pause.
2393 // First, during_initial_mark_pause() should not be already set. We
2394 // will set it here if we have to. However, it should be cleared by
2395 // the end of the pause (it's only set for the duration of an
2396 // initial-mark pause).
2397 assert(!during_initial_mark_pause(), "pre-condition");
2399 if (initiate_conc_mark_if_possible()) {
2400 // We had noticed on a previous pause that the heap occupancy has
2401 // gone over the initiating threshold and we should start a
2402 // concurrent marking cycle. So we might initiate one.
2404 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2405 if (!during_cycle) {
2406 // The concurrent marking thread is not "during a cycle", i.e.,
2407 // it has completed the last one. So we can go ahead and
2408 // initiate a new cycle.
2410 set_during_initial_mark_pause();
2412 // And we can now clear initiate_conc_mark_if_possible() as
2413 // we've already acted on it.
2414 clear_initiate_conc_mark_if_possible();
2415 } else {
2416 // The concurrent marking thread is still finishing up the
2417 // previous cycle. If we start one right now the two cycles
2418 // overlap. In particular, the concurrent marking thread might
2419 // be in the process of clearing the next marking bitmap (which
2420 // we will use for the next cycle if we start one). Starting a
2421 // cycle now will be bad given that parts of the marking
2422 // information might get cleared by the marking thread. And we
2423 // cannot wait for the marking thread to finish the cycle as it
2424 // periodically yields while clearing the next marking bitmap
2425 // and, if it's in a yield point, it's waiting for us to
2426 // finish. So, at this point we will not start a cycle and we'll
2427 // let the concurrent marking thread complete the last one.
2428 }
2429 }
2430 }
2432 void
2433 G1CollectorPolicy_BestRegionsFirst::
2434 record_collection_pause_start(double start_time_sec, size_t start_used) {
2435 G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
2436 }
2438 class NextNonCSElemFinder: public HeapRegionClosure {
2439 HeapRegion* _res;
2440 public:
2441 NextNonCSElemFinder(): _res(NULL) {}
2442 bool doHeapRegion(HeapRegion* r) {
2443 if (!r->in_collection_set()) {
2444 _res = r;
2445 return true;
2446 } else {
2447 return false;
2448 }
2449 }
2450 HeapRegion* res() { return _res; }
2451 };
2453 class KnownGarbageClosure: public HeapRegionClosure {
2454 CollectionSetChooser* _hrSorted;
2456 public:
2457 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2458 _hrSorted(hrSorted)
2459 {}
2461 bool doHeapRegion(HeapRegion* r) {
2462 // We only include humongous regions in collection
2463 // sets when concurrent mark shows that their contained object is
2464 // unreachable.
2466 // Do we have any marking information for this region?
2467 if (r->is_marked()) {
2468 // We don't include humongous regions in collection
2469 // sets because we collect them immediately at the end of a marking
2470 // cycle. We also don't include young regions because we *must*
2471 // include them in the next collection pause.
2472 if (!r->isHumongous() && !r->is_young()) {
2473 _hrSorted->addMarkedHeapRegion(r);
2474 }
2475 }
2476 return false;
2477 }
2478 };
2480 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2481 CollectionSetChooser* _hrSorted;
2482 jint _marked_regions_added;
2483 jint _chunk_size;
2484 jint _cur_chunk_idx;
2485 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2486 int _worker;
2487 int _invokes;
2489 void get_new_chunk() {
2490 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2491 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2492 }
2493 void add_region(HeapRegion* r) {
2494 if (_cur_chunk_idx == _cur_chunk_end) {
2495 get_new_chunk();
2496 }
2497 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2498 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2499 _marked_regions_added++;
2500 _cur_chunk_idx++;
2501 }
2503 public:
2504 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2505 jint chunk_size,
2506 int worker) :
2507 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2508 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2509 _invokes(0)
2510 {}
2512 bool doHeapRegion(HeapRegion* r) {
2513 // We only include humongous regions in collection
2514 // sets when concurrent mark shows that their contained object is
2515 // unreachable.
2516 _invokes++;
2518 // Do we have any marking information for this region?
2519 if (r->is_marked()) {
2520 // We don't include humongous regions in collection
2521 // sets because we collect them immediately at the end of a marking
2522 // cycle.
2523 // We also do not include young regions in collection sets
2524 if (!r->isHumongous() && !r->is_young()) {
2525 add_region(r);
2526 }
2527 }
2528 return false;
2529 }
2530 jint marked_regions_added() { return _marked_regions_added; }
2531 int invokes() { return _invokes; }
2532 };
2534 class ParKnownGarbageTask: public AbstractGangTask {
2535 CollectionSetChooser* _hrSorted;
2536 jint _chunk_size;
2537 G1CollectedHeap* _g1;
2538 public:
2539 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2540 AbstractGangTask("ParKnownGarbageTask"),
2541 _hrSorted(hrSorted), _chunk_size(chunk_size),
2542 _g1(G1CollectedHeap::heap())
2543 {}
2545 void work(int i) {
2546 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2547 // Back to zero for the claim value.
2548 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2549 HeapRegion::InitialClaimValue);
2550 jint regions_added = parKnownGarbageCl.marked_regions_added();
2551 _hrSorted->incNumMarkedHeapRegions(regions_added);
2552 if (G1PrintParCleanupStats) {
2553 gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
2554 i, parKnownGarbageCl.invokes(), regions_added);
2555 }
2556 }
2557 };
2559 void
2560 G1CollectorPolicy_BestRegionsFirst::
2561 record_concurrent_mark_cleanup_end(size_t freed_bytes,
2562 size_t max_live_bytes) {
2563 double start;
2564 if (G1PrintParCleanupStats) start = os::elapsedTime();
2565 record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
2567 _collectionSetChooser->clearMarkedHeapRegions();
2568 double clear_marked_end;
2569 if (G1PrintParCleanupStats) {
2570 clear_marked_end = os::elapsedTime();
2571 gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
2572 (clear_marked_end - start)*1000.0);
2573 }
2574 if (G1CollectedHeap::use_parallel_gc_threads()) {
2575 const size_t OverpartitionFactor = 4;
2576 const size_t MinWorkUnit = 8;
2577 const size_t WorkUnit =
2578 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2579 MinWorkUnit);
2580 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2581 WorkUnit);
2582 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2583 (int) WorkUnit);
2584 _g1->workers()->run_task(&parKnownGarbageTask);
2586 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2587 "sanity check");
2588 } else {
2589 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2590 _g1->heap_region_iterate(&knownGarbagecl);
2591 }
2592 double known_garbage_end;
2593 if (G1PrintParCleanupStats) {
2594 known_garbage_end = os::elapsedTime();
2595 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2596 (known_garbage_end - clear_marked_end)*1000.0);
2597 }
2598 _collectionSetChooser->sortMarkedHeapRegions();
2599 double sort_end;
2600 if (G1PrintParCleanupStats) {
2601 sort_end = os::elapsedTime();
2602 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2603 (sort_end - known_garbage_end)*1000.0);
2604 }
2606 record_concurrent_mark_cleanup_end_work2();
2607 double work2_end;
2608 if (G1PrintParCleanupStats) {
2609 work2_end = os::elapsedTime();
2610 gclog_or_tty->print_cr(" work2: %8.3f ms.",
2611 (work2_end - sort_end)*1000.0);
2612 }
2613 }
2615 // Add the heap region at the head of the non-incremental collection set
2616 void G1CollectorPolicy::
2617 add_to_collection_set(HeapRegion* hr) {
2618 assert(_inc_cset_build_state == Active, "Precondition");
2619 assert(!hr->is_young(), "non-incremental add of young region");
2621 if (G1PrintHeapRegions) {
2622 gclog_or_tty->print_cr("added region to cset "
2623 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2624 "top "PTR_FORMAT", %s",
2625 hr->hrs_index(), hr->bottom(), hr->end(),
2626 hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
2627 }
2629 if (_g1->mark_in_progress())
2630 _g1->concurrent_mark()->registerCSetRegion(hr);
2632 assert(!hr->in_collection_set(), "should not already be in the CSet");
2633 hr->set_in_collection_set(true);
2634 hr->set_next_in_collection_set(_collection_set);
2635 _collection_set = hr;
2636 _collection_set_size++;
2637 _collection_set_bytes_used_before += hr->used();
2638 _g1->register_region_with_in_cset_fast_test(hr);
2639 }
2641 // Initialize the per-collection-set information
2642 void G1CollectorPolicy::start_incremental_cset_building() {
2643 assert(_inc_cset_build_state == Inactive, "Precondition");
2645 _inc_cset_head = NULL;
2646 _inc_cset_tail = NULL;
2647 _inc_cset_size = 0;
2648 _inc_cset_bytes_used_before = 0;
2650 if (in_young_gc_mode()) {
2651 _inc_cset_young_index = 0;
2652 }
2654 _inc_cset_max_finger = 0;
2655 _inc_cset_recorded_young_bytes = 0;
2656 _inc_cset_recorded_rs_lengths = 0;
2657 _inc_cset_predicted_elapsed_time_ms = 0;
2658 _inc_cset_predicted_bytes_to_copy = 0;
2659 _inc_cset_build_state = Active;
2660 }
2662 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2663 // This routine is used when:
2664 // * adding survivor regions to the incremental cset at the end of an
2665 // evacuation pause,
2666 // * adding the current allocation region to the incremental cset
2667 // when it is retired, and
2668 // * updating existing policy information for a region in the
2669 // incremental cset via young list RSet sampling.
2670 // Therefore this routine may be called at a safepoint by the
2671 // VM thread, or in-between safepoints by mutator threads (when
2672 // retiring the current allocation region) or a concurrent
2673 // refine thread (RSet sampling).
2675 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2676 size_t used_bytes = hr->used();
2678 _inc_cset_recorded_rs_lengths += rs_length;
2679 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2681 _inc_cset_bytes_used_before += used_bytes;
2683 // Cache the values we have added to the aggregated informtion
2684 // in the heap region in case we have to remove this region from
2685 // the incremental collection set, or it is updated by the
2686 // rset sampling code
2687 hr->set_recorded_rs_length(rs_length);
2688 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2690 #if PREDICTIONS_VERBOSE
2691 size_t bytes_to_copy = predict_bytes_to_copy(hr);
2692 _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
2694 // Record the number of bytes used in this region
2695 _inc_cset_recorded_young_bytes += used_bytes;
2697 // Cache the values we have added to the aggregated informtion
2698 // in the heap region in case we have to remove this region from
2699 // the incremental collection set, or it is updated by the
2700 // rset sampling code
2701 hr->set_predicted_bytes_to_copy(bytes_to_copy);
2702 #endif // PREDICTIONS_VERBOSE
2703 }
2705 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2706 // This routine is currently only called as part of the updating of
2707 // existing policy information for regions in the incremental cset that
2708 // is performed by the concurrent refine thread(s) as part of young list
2709 // RSet sampling. Therefore we should not be at a safepoint.
2711 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2712 assert(hr->is_young(), "it should be");
2714 size_t used_bytes = hr->used();
2715 size_t old_rs_length = hr->recorded_rs_length();
2716 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2718 // Subtract the old recorded/predicted policy information for
2719 // the given heap region from the collection set info.
2720 _inc_cset_recorded_rs_lengths -= old_rs_length;
2721 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2723 _inc_cset_bytes_used_before -= used_bytes;
2725 // Clear the values cached in the heap region
2726 hr->set_recorded_rs_length(0);
2727 hr->set_predicted_elapsed_time_ms(0);
2729 #if PREDICTIONS_VERBOSE
2730 size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
2731 _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
2733 // Subtract the number of bytes used in this region
2734 _inc_cset_recorded_young_bytes -= used_bytes;
2736 // Clear the values cached in the heap region
2737 hr->set_predicted_bytes_to_copy(0);
2738 #endif // PREDICTIONS_VERBOSE
2739 }
2741 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2742 // Update the collection set information that is dependent on the new RS length
2743 assert(hr->is_young(), "Precondition");
2745 remove_from_incremental_cset_info(hr);
2746 add_to_incremental_cset_info(hr, new_rs_length);
2747 }
2749 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2750 assert( hr->is_young(), "invariant");
2751 assert( hr->young_index_in_cset() == -1, "invariant" );
2752 assert(_inc_cset_build_state == Active, "Precondition");
2754 // We need to clear and set the cached recorded/cached collection set
2755 // information in the heap region here (before the region gets added
2756 // to the collection set). An individual heap region's cached values
2757 // are calculated, aggregated with the policy collection set info,
2758 // and cached in the heap region here (initially) and (subsequently)
2759 // by the Young List sampling code.
2761 size_t rs_length = hr->rem_set()->occupied();
2762 add_to_incremental_cset_info(hr, rs_length);
2764 HeapWord* hr_end = hr->end();
2765 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2767 assert(!hr->in_collection_set(), "invariant");
2768 hr->set_in_collection_set(true);
2769 assert( hr->next_in_collection_set() == NULL, "invariant");
2771 _inc_cset_size++;
2772 _g1->register_region_with_in_cset_fast_test(hr);
2774 hr->set_young_index_in_cset((int) _inc_cset_young_index);
2775 ++_inc_cset_young_index;
2776 }
2778 // Add the region at the RHS of the incremental cset
2779 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2780 // We should only ever be appending survivors at the end of a pause
2781 assert( hr->is_survivor(), "Logic");
2783 // Do the 'common' stuff
2784 add_region_to_incremental_cset_common(hr);
2786 // Now add the region at the right hand side
2787 if (_inc_cset_tail == NULL) {
2788 assert(_inc_cset_head == NULL, "invariant");
2789 _inc_cset_head = hr;
2790 } else {
2791 _inc_cset_tail->set_next_in_collection_set(hr);
2792 }
2793 _inc_cset_tail = hr;
2795 if (G1PrintHeapRegions) {
2796 gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
2797 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2798 "top "PTR_FORMAT", young %s",
2799 hr->hrs_index(), hr->bottom(), hr->end(),
2800 hr->top(), (hr->is_young()) ? "YES" : "NO");
2801 }
2802 }
2804 // Add the region to the LHS of the incremental cset
2805 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2806 // Survivors should be added to the RHS at the end of a pause
2807 assert(!hr->is_survivor(), "Logic");
2809 // Do the 'common' stuff
2810 add_region_to_incremental_cset_common(hr);
2812 // Add the region at the left hand side
2813 hr->set_next_in_collection_set(_inc_cset_head);
2814 if (_inc_cset_head == NULL) {
2815 assert(_inc_cset_tail == NULL, "Invariant");
2816 _inc_cset_tail = hr;
2817 }
2818 _inc_cset_head = hr;
2820 if (G1PrintHeapRegions) {
2821 gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
2822 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
2823 "top "PTR_FORMAT", young %s",
2824 hr->hrs_index(), hr->bottom(), hr->end(),
2825 hr->top(), (hr->is_young()) ? "YES" : "NO");
2826 }
2827 }
2829 #ifndef PRODUCT
2830 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2831 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2833 st->print_cr("\nCollection_set:");
2834 HeapRegion* csr = list_head;
2835 while (csr != NULL) {
2836 HeapRegion* next = csr->next_in_collection_set();
2837 assert(csr->in_collection_set(), "bad CS");
2838 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2839 "age: %4d, y: %d, surv: %d",
2840 csr->bottom(), csr->end(),
2841 csr->top(),
2842 csr->prev_top_at_mark_start(),
2843 csr->next_top_at_mark_start(),
2844 csr->top_at_conc_mark_count(),
2845 csr->age_in_surv_rate_group_cond(),
2846 csr->is_young(),
2847 csr->is_survivor());
2848 csr = next;
2849 }
2850 }
2851 #endif // !PRODUCT
2853 void
2854 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
2855 double target_pause_time_ms) {
2856 // Set this here - in case we're not doing young collections.
2857 double non_young_start_time_sec = os::elapsedTime();
2859 start_recording_regions();
2861 guarantee(target_pause_time_ms > 0.0,
2862 err_msg("target_pause_time_ms = %1.6lf should be positive",
2863 target_pause_time_ms));
2864 guarantee(_collection_set == NULL, "Precondition");
2866 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2867 double predicted_pause_time_ms = base_time_ms;
2869 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2871 // the 10% and 50% values are arbitrary...
2872 if (time_remaining_ms < 0.10 * target_pause_time_ms) {
2873 time_remaining_ms = 0.50 * target_pause_time_ms;
2874 _within_target = false;
2875 } else {
2876 _within_target = true;
2877 }
2879 // We figure out the number of bytes available for future to-space.
2880 // For new regions without marking information, we must assume the
2881 // worst-case of complete survival. If we have marking information for a
2882 // region, we can bound the amount of live data. We can add a number of
2883 // such regions, as long as the sum of the live data bounds does not
2884 // exceed the available evacuation space.
2885 size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
2887 size_t expansion_bytes =
2888 _g1->expansion_regions() * HeapRegion::GrainBytes;
2890 _collection_set_bytes_used_before = 0;
2891 _collection_set_size = 0;
2893 // Adjust for expansion and slop.
2894 max_live_bytes = max_live_bytes + expansion_bytes;
2896 HeapRegion* hr;
2897 if (in_young_gc_mode()) {
2898 double young_start_time_sec = os::elapsedTime();
2900 if (G1PolicyVerbose > 0) {
2901 gclog_or_tty->print_cr("Adding %d young regions to the CSet",
2902 _g1->young_list()->length());
2903 }
2905 _young_cset_length = 0;
2906 _last_young_gc_full = full_young_gcs() ? true : false;
2908 if (_last_young_gc_full)
2909 ++_full_young_pause_num;
2910 else
2911 ++_partial_young_pause_num;
2913 // The young list is laid with the survivor regions from the previous
2914 // pause are appended to the RHS of the young list, i.e.
2915 // [Newly Young Regions ++ Survivors from last pause].
2917 hr = _g1->young_list()->first_survivor_region();
2918 while (hr != NULL) {
2919 assert(hr->is_survivor(), "badly formed young list");
2920 hr->set_young();
2921 hr = hr->get_next_young_region();
2922 }
2924 // Clear the fields that point to the survivor list - they are
2925 // all young now.
2926 _g1->young_list()->clear_survivors();
2928 if (_g1->mark_in_progress())
2929 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2931 _young_cset_length = _inc_cset_young_index;
2932 _collection_set = _inc_cset_head;
2933 _collection_set_size = _inc_cset_size;
2934 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2936 // For young regions in the collection set, we assume the worst
2937 // case of complete survival
2938 max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
2940 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2941 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2943 // The number of recorded young regions is the incremental
2944 // collection set's current size
2945 set_recorded_young_regions(_inc_cset_size);
2946 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2947 set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
2948 #if PREDICTIONS_VERBOSE
2949 set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
2950 #endif // PREDICTIONS_VERBOSE
2952 if (G1PolicyVerbose > 0) {
2953 gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
2954 _inc_cset_size);
2955 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2956 max_live_bytes/K);
2957 }
2959 assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
2961 double young_end_time_sec = os::elapsedTime();
2962 _recorded_young_cset_choice_time_ms =
2963 (young_end_time_sec - young_start_time_sec) * 1000.0;
2965 // We are doing young collections so reset this.
2966 non_young_start_time_sec = young_end_time_sec;
2968 // Note we can use either _collection_set_size or
2969 // _young_cset_length here
2970 if (_collection_set_size > 0 && _last_young_gc_full) {
2971 // don't bother adding more regions...
2972 goto choose_collection_set_end;
2973 }
2974 }
2976 if (!in_young_gc_mode() || !full_young_gcs()) {
2977 bool should_continue = true;
2978 NumberSeq seq;
2979 double avg_prediction = 100000000000000000.0; // something very large
2981 do {
2982 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2983 avg_prediction);
2984 if (hr != NULL) {
2985 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2986 time_remaining_ms -= predicted_time_ms;
2987 predicted_pause_time_ms += predicted_time_ms;
2988 add_to_collection_set(hr);
2989 record_non_young_cset_region(hr);
2990 max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
2991 if (G1PolicyVerbose > 0) {
2992 gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
2993 max_live_bytes/K);
2994 }
2995 seq.add(predicted_time_ms);
2996 avg_prediction = seq.avg() + seq.sd();
2997 }
2998 should_continue =
2999 ( hr != NULL) &&
3000 ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
3001 : _collection_set_size < _young_list_fixed_length );
3002 } while (should_continue);
3004 if (!adaptive_young_list_length() &&
3005 _collection_set_size < _young_list_fixed_length)
3006 _should_revert_to_full_young_gcs = true;
3007 }
3009 choose_collection_set_end:
3010 stop_incremental_cset_building();
3012 count_CS_bytes_used();
3014 end_recording_regions();
3016 double non_young_end_time_sec = os::elapsedTime();
3017 _recorded_non_young_cset_choice_time_ms =
3018 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
3019 }
3021 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
3022 G1CollectorPolicy::record_full_collection_end();
3023 _collectionSetChooser->updateAfterFullCollection();
3024 }
3026 void G1CollectorPolicy_BestRegionsFirst::
3027 expand_if_possible(size_t numRegions) {
3028 size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
3029 _g1->expand(expansion_bytes);
3030 }
3032 void G1CollectorPolicy_BestRegionsFirst::
3033 record_collection_pause_end() {
3034 G1CollectorPolicy::record_collection_pause_end();
3035 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
3036 }