1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/g1Log.hpp"
33 #include "gc_implementation/g1/heapRegionRemSet.hpp"
34 #include "gc_implementation/shared/gcPolicyCounters.hpp"
35 #include "runtime/arguments.hpp"
36 #include "runtime/java.hpp"
37 #include "runtime/mutexLocker.hpp"
38 #include "utilities/debug.hpp"
39
40 // Different defaults for different number of GC threads
41 // They were chosen by running GCOld and SPECjbb on debris with different
42 // numbers of GC threads and choosing them based on the results
43
44 // all the same
45 static double rs_length_diff_defaults[] = {
46 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
47 };
48
49 static double cost_per_card_ms_defaults[] = {
50 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
51 };
52
53 // all the same
54 static double young_cards_per_entry_ratio_defaults[] = {
55 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
56 };
57
58 static double cost_per_entry_ms_defaults[] = {
59 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
60 };
61
62 static double cost_per_byte_ms_defaults[] = {
63 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
64 };
65
66 // these should be pretty consistent
67 static double constant_other_time_ms_defaults[] = {
68 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
69 };
70
71
72 static double young_other_cost_per_region_ms_defaults[] = {
73 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
74 };
75
76 static double non_young_other_cost_per_region_ms_defaults[] = {
77 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
78 };
79
80 // Help class for avoiding interleaved logging
81 class LineBuffer: public StackObj {
82
83 private:
84 static const int BUFFER_LEN = 1024;
85 static const int INDENT_CHARS = 3;
86 char _buffer[BUFFER_LEN];
87 int _indent_level;
88 int _cur;
89
90 void vappend(const char* format, va_list ap) {
91 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
92 if (res != -1) {
93 _cur += res;
94 } else {
95 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
96 _buffer[BUFFER_LEN -1] = 0;
97 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
98 }
99 }
100
101 public:
102 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
103 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
104 _buffer[_cur] = ' ';
105 }
106 }
107
108 #ifndef PRODUCT
109 ~LineBuffer() {
110 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
111 }
112 #endif
113
114 void append(const char* format, ...) {
115 va_list ap;
116 va_start(ap, format);
117 vappend(format, ap);
118 va_end(ap);
119 }
120
121 void append_and_print_cr(const char* format, ...) {
122 va_list ap;
123 va_start(ap, format);
124 vappend(format, ap);
125 va_end(ap);
126 gclog_or_tty->print_cr("%s", _buffer);
127 _cur = _indent_level * INDENT_CHARS;
128 }
129 };
130
131 G1CollectorPolicy::G1CollectorPolicy() :
132 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
133 ? ParallelGCThreads : 1),
134
135 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
136 _stop_world_start(0.0),
137
138 _cur_clear_ct_time_ms(0.0),
139 _root_region_scan_wait_time_ms(0.0),
140
141 _cur_ref_proc_time_ms(0.0),
142 _cur_ref_enq_time_ms(0.0),
143
144 #ifndef PRODUCT
145 _min_clear_cc_time_ms(-1.0),
146 _max_clear_cc_time_ms(-1.0),
147 _cur_clear_cc_time_ms(0.0),
148 _cum_clear_cc_time_ms(0.0),
149 _num_cc_clears(0L),
150 #endif
151
152 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
153 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
154
155 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
156 _prev_collection_pause_end_ms(0.0),
157 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
158 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
159 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
160 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
161 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
162 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
163 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
164 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
165 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
166 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
167 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
168 _non_young_other_cost_per_region_ms_seq(
169 new TruncatedSeq(TruncatedSeqLength)),
170
171 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
172 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
173
174 _pause_time_target_ms((double) MaxGCPauseMillis),
175
176 _gcs_are_young(true),
177
178 _during_marking(false),
179 _in_marking_window(false),
180 _in_marking_window_im(false),
181
182 _recent_prev_end_times_for_all_gcs_sec(
183 new TruncatedSeq(NumPrevPausesForHeuristics)),
184
185 _recent_avg_pause_time_ratio(0.0),
186
187 _initiate_conc_mark_if_possible(false),
188 _during_initial_mark_pause(false),
189 _last_young_gc(false),
190 _last_gc_was_young(false),
191
192 _eden_bytes_before_gc(0),
193 _survivor_bytes_before_gc(0),
194 _capacity_before_gc(0),
195
196 _eden_cset_region_length(0),
197 _survivor_cset_region_length(0),
198 _old_cset_region_length(0),
199
200 _collection_set(NULL),
201 _collection_set_bytes_used_before(0),
202
203 // Incremental CSet attributes
204 _inc_cset_build_state(Inactive),
205 _inc_cset_head(NULL),
206 _inc_cset_tail(NULL),
207 _inc_cset_bytes_used_before(0),
208 _inc_cset_max_finger(NULL),
209 _inc_cset_recorded_rs_lengths(0),
210 _inc_cset_recorded_rs_lengths_diffs(0),
211 _inc_cset_predicted_elapsed_time_ms(0.0),
212 _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
213
214 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
215 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
216 #endif // _MSC_VER
217
218 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
219 G1YoungSurvRateNumRegionsSummary)),
220 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
221 G1YoungSurvRateNumRegionsSummary)),
222 // add here any more surv rate groups
223 _recorded_survivor_regions(0),
224 _recorded_survivor_head(NULL),
225 _recorded_survivor_tail(NULL),
226 _survivors_age_table(true),
227
228 _gc_overhead_perc(0.0) {
229
230 // Set up the region size and associated fields. Given that the
231 // policy is created before the heap, we have to set this up here,
232 // so it's done as soon as possible.
233 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
234 HeapRegionRemSet::setup_remset_size();
235
236 G1ErgoVerbose::initialize();
237 if (PrintAdaptiveSizePolicy) {
238 // Currently, we only use a single switch for all the heuristics.
239 G1ErgoVerbose::set_enabled(true);
240 // Given that we don't currently have a verboseness level
241 // parameter, we'll hardcode this to high. This can be easily
242 // changed in the future.
243 G1ErgoVerbose::set_level(ErgoHigh);
244 } else {
245 G1ErgoVerbose::set_enabled(false);
246 }
247
248 // Verify PLAB sizes
249 const size_t region_size = HeapRegion::GrainWords;
250 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
251 char buffer[128];
252 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
253 OldPLABSize > region_size ? "Old" : "Young", region_size);
254 vm_exit_during_initialization(buffer);
255 }
256
257 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
258 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
259
260 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
261 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
262 _par_last_satb_filtering_times_ms = new double[_parallel_gc_threads];
263
264 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
265 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
266
267 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
268
269 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
270
271 _par_last_termination_times_ms = new double[_parallel_gc_threads];
272 _par_last_termination_attempts = new double[_parallel_gc_threads];
273 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
274 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
275 _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
276
277 int index;
278 if (ParallelGCThreads == 0)
279 index = 0;
280 else if (ParallelGCThreads > 8)
281 index = 7;
282 else
283 index = ParallelGCThreads - 1;
284
285 _pending_card_diff_seq->add(0.0);
286 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
287 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
288 _young_cards_per_entry_ratio_seq->add(
289 young_cards_per_entry_ratio_defaults[index]);
290 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
291 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
292 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
293 _young_other_cost_per_region_ms_seq->add(
294 young_other_cost_per_region_ms_defaults[index]);
295 _non_young_other_cost_per_region_ms_seq->add(
296 non_young_other_cost_per_region_ms_defaults[index]);
297
298 // Below, we might need to calculate the pause time target based on
299 // the pause interval. When we do so we are going to give G1 maximum
300 // flexibility and allow it to do pauses when it needs to. So, we'll
301 // arrange that the pause interval to be pause time target + 1 to
302 // ensure that a) the pause time target is maximized with respect to
303 // the pause interval and b) we maintain the invariant that pause
304 // time target < pause interval. If the user does not want this
305 // maximum flexibility, they will have to set the pause interval
306 // explicitly.
307
308 // First make sure that, if either parameter is set, its value is
309 // reasonable.
310 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
311 if (MaxGCPauseMillis < 1) {
312 vm_exit_during_initialization("MaxGCPauseMillis should be "
313 "greater than 0");
314 }
315 }
316 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
317 if (GCPauseIntervalMillis < 1) {
318 vm_exit_during_initialization("GCPauseIntervalMillis should be "
319 "greater than 0");
320 }
321 }
322
323 // Then, if the pause time target parameter was not set, set it to
324 // the default value.
325 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
326 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
327 // The default pause time target in G1 is 200ms
328 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
329 } else {
330 // We do not allow the pause interval to be set without the
331 // pause time target
332 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
333 "without setting MaxGCPauseMillis");
334 }
335 }
336
337 // Then, if the interval parameter was not set, set it according to
338 // the pause time target (this will also deal with the case when the
339 // pause time target is the default value).
340 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
341 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
342 }
343
344 // Finally, make sure that the two parameters are consistent.
345 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
346 char buffer[256];
347 jio_snprintf(buffer, 256,
348 "MaxGCPauseMillis (%u) should be less than "
349 "GCPauseIntervalMillis (%u)",
350 MaxGCPauseMillis, GCPauseIntervalMillis);
351 vm_exit_during_initialization(buffer);
352 }
353
354 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
355 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
356 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
357 _sigma = (double) G1ConfidencePercent / 100.0;
358
359 // start conservatively (around 50ms is about right)
360 _concurrent_mark_remark_times_ms->add(0.05);
361 _concurrent_mark_cleanup_times_ms->add(0.20);
362 _tenuring_threshold = MaxTenuringThreshold;
363 // _max_survivor_regions will be calculated by
364 // update_young_list_target_length() during initialization.
365 _max_survivor_regions = 0;
366
367 assert(GCTimeRatio > 0,
368 "we should have set it to a default value set_g1_gc_flags() "
369 "if a user set it to 0");
370 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
371
372 uintx reserve_perc = G1ReservePercent;
373 // Put an artificial ceiling on this so that it's not set to a silly value.
374 if (reserve_perc > 50) {
375 reserve_perc = 50;
376 warning("G1ReservePercent is set to a value that is too large, "
377 "it's been updated to %u", reserve_perc);
378 }
379 _reserve_factor = (double) reserve_perc / 100.0;
380 // This will be set when the heap is expanded
381 // for the first time during initialization.
382 _reserve_regions = 0;
383
384 initialize_all();
385 _collectionSetChooser = new CollectionSetChooser();
386 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
387 }
388
389 void G1CollectorPolicy::initialize_flags() {
390 set_min_alignment(HeapRegion::GrainBytes);
391 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
392 if (SurvivorRatio < 1) {
393 vm_exit_during_initialization("Invalid survivor ratio specified");
394 }
395 CollectorPolicy::initialize_flags();
396 }
397
398 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
399 assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");
400 assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");
401 assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");
402
403 if (FLAG_IS_CMDLINE(NewRatio)) {
404 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
405 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
406 } else {
407 _sizer_kind = SizerNewRatio;
408 _adaptive_size = false;
409 return;
410 }
411 }
412
413 if (FLAG_IS_CMDLINE(NewSize)) {
414 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
415 1U);
416 if (FLAG_IS_CMDLINE(MaxNewSize)) {
417 _max_desired_young_length =
418 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
419 1U);
420 _sizer_kind = SizerMaxAndNewSize;
421 _adaptive_size = _min_desired_young_length == _max_desired_young_length;
422 } else {
423 _sizer_kind = SizerNewSizeOnly;
424 }
425 } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
426 _max_desired_young_length =
427 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
428 1U);
429 _sizer_kind = SizerMaxNewSizeOnly;
430 }
431 }
432
433 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
434 uint default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;
435 return MAX2(1U, default_value);
436 }
437
438 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
439 uint default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;
440 return MAX2(1U, default_value);
441 }
442
443 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
444 assert(new_number_of_heap_regions > 0, "Heap must be initialized");
445
446 switch (_sizer_kind) {
447 case SizerDefaults:
448 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
449 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
450 break;
451 case SizerNewSizeOnly:
452 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
453 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
454 break;
455 case SizerMaxNewSizeOnly:
456 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
457 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
458 break;
459 case SizerMaxAndNewSize:
460 // Do nothing. Values set on the command line, don't update them at runtime.
461 break;
462 case SizerNewRatio:
463 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
464 _max_desired_young_length = _min_desired_young_length;
465 break;
466 default:
467 ShouldNotReachHere();
468 }
469
470 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
471 }
472
473 void G1CollectorPolicy::init() {
474 // Set aside an initial future to_space.
475 _g1 = G1CollectedHeap::heap();
476
477 assert(Heap_lock->owned_by_self(), "Locking discipline.");
478
479 initialize_gc_policy_counters();
480
481 if (adaptive_young_list_length()) {
482 _young_list_fixed_length = 0;
483 } else {
484 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
485 }
486 _free_regions_at_end_of_collection = _g1->free_regions();
487 update_young_list_target_length();
488 _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
489
490 // We may immediately start allocating regions and placing them on the
491 // collection set list. Initialize the per-collection set info
492 start_incremental_cset_building();
493 }
494
495 // Create the jstat counters for the policy.
496 void G1CollectorPolicy::initialize_gc_policy_counters() {
497 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
498 }
499
500 bool G1CollectorPolicy::predict_will_fit(uint young_length,
501 double base_time_ms,
502 uint base_free_regions,
503 double target_pause_time_ms) {
504 if (young_length >= base_free_regions) {
505 // end condition 1: not enough space for the young regions
506 return false;
507 }
508
509 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
510 size_t bytes_to_copy =
511 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
512 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
513 double young_other_time_ms = predict_young_other_time_ms(young_length);
514 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
515 if (pause_time_ms > target_pause_time_ms) {
516 // end condition 2: prediction is over the target pause time
517 return false;
518 }
519
520 size_t free_bytes =
521 (base_free_regions - young_length) * HeapRegion::GrainBytes;
522 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
523 // end condition 3: out-of-space (conservatively!)
524 return false;
525 }
526
527 // success!
528 return true;
529 }
530
531 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
532 // re-calculate the necessary reserve
533 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
534 // We use ceiling so that if reserve_regions_d is > 0.0 (but
535 // smaller than 1.0) we'll get 1.
536 _reserve_regions = (uint) ceil(reserve_regions_d);
537
538 _young_gen_sizer->heap_size_changed(new_number_of_regions);
539 }
540
541 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
542 uint base_min_length) {
543 uint desired_min_length = 0;
544 if (adaptive_young_list_length()) {
545 if (_alloc_rate_ms_seq->num() > 3) {
546 double now_sec = os::elapsedTime();
547 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
548 double alloc_rate_ms = predict_alloc_rate_ms();
549 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
550 } else {
551 // otherwise we don't have enough info to make the prediction
552 }
553 }
554 desired_min_length += base_min_length;
555 // make sure we don't go below any user-defined minimum bound
556 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
557 }
558
559 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
560 // Here, we might want to also take into account any additional
561 // constraints (i.e., user-defined minimum bound). Currently, we
562 // effectively don't set this bound.
563 return _young_gen_sizer->max_desired_young_length();
564 }
565
566 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
567 if (rs_lengths == (size_t) -1) {
568 // if it's set to the default value (-1), we should predict it;
569 // otherwise, use the given value.
570 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
571 }
572
573 // Calculate the absolute and desired min bounds.
574
575 // This is how many young regions we already have (currently: the survivors).
576 uint base_min_length = recorded_survivor_regions();
577 // This is the absolute minimum young length, which ensures that we
578 // can allocate one eden region in the worst-case.
579 uint absolute_min_length = base_min_length + 1;
580 uint desired_min_length =
581 calculate_young_list_desired_min_length(base_min_length);
582 if (desired_min_length < absolute_min_length) {
583 desired_min_length = absolute_min_length;
584 }
585
586 // Calculate the absolute and desired max bounds.
587
588 // We will try our best not to "eat" into the reserve.
589 uint absolute_max_length = 0;
590 if (_free_regions_at_end_of_collection > _reserve_regions) {
591 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
592 }
593 uint desired_max_length = calculate_young_list_desired_max_length();
594 if (desired_max_length > absolute_max_length) {
595 desired_max_length = absolute_max_length;
596 }
597
598 uint young_list_target_length = 0;
599 if (adaptive_young_list_length()) {
600 if (gcs_are_young()) {
601 young_list_target_length =
602 calculate_young_list_target_length(rs_lengths,
603 base_min_length,
604 desired_min_length,
605 desired_max_length);
606 _rs_lengths_prediction = rs_lengths;
607 } else {
608 // Don't calculate anything and let the code below bound it to
609 // the desired_min_length, i.e., do the next GC as soon as
610 // possible to maximize how many old regions we can add to it.
611 }
612 } else {
613 // The user asked for a fixed young gen so we'll fix the young gen
614 // whether the next GC is young or mixed.
615 young_list_target_length = _young_list_fixed_length;
616 }
617
618 // Make sure we don't go over the desired max length, nor under the
619 // desired min length. In case they clash, desired_min_length wins
620 // which is why that test is second.
621 if (young_list_target_length > desired_max_length) {
622 young_list_target_length = desired_max_length;
623 }
624 if (young_list_target_length < desired_min_length) {
625 young_list_target_length = desired_min_length;
626 }
627
628 assert(young_list_target_length > recorded_survivor_regions(),
629 "we should be able to allocate at least one eden region");
630 assert(young_list_target_length >= absolute_min_length, "post-condition");
631 _young_list_target_length = young_list_target_length;
632
633 update_max_gc_locker_expansion();
634 }
635
636 uint
637 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
638 uint base_min_length,
639 uint desired_min_length,
640 uint desired_max_length) {
641 assert(adaptive_young_list_length(), "pre-condition");
642 assert(gcs_are_young(), "only call this for young GCs");
643
644 // In case some edge-condition makes the desired max length too small...
645 if (desired_max_length <= desired_min_length) {
646 return desired_min_length;
647 }
648
649 // We'll adjust min_young_length and max_young_length not to include
650 // the already allocated young regions (i.e., so they reflect the
651 // min and max eden regions we'll allocate). The base_min_length
652 // will be reflected in the predictions by the
653 // survivor_regions_evac_time prediction.
654 assert(desired_min_length > base_min_length, "invariant");
655 uint min_young_length = desired_min_length - base_min_length;
656 assert(desired_max_length > base_min_length, "invariant");
657 uint max_young_length = desired_max_length - base_min_length;
658
659 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
660 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
661 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
662 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
663 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
664 double base_time_ms =
665 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
666 survivor_regions_evac_time;
667 uint available_free_regions = _free_regions_at_end_of_collection;
668 uint base_free_regions = 0;
669 if (available_free_regions > _reserve_regions) {
670 base_free_regions = available_free_regions - _reserve_regions;
671 }
672
673 // Here, we will make sure that the shortest young length that
674 // makes sense fits within the target pause time.
675
676 if (predict_will_fit(min_young_length, base_time_ms,
677 base_free_regions, target_pause_time_ms)) {
678 // The shortest young length will fit into the target pause time;
679 // we'll now check whether the absolute maximum number of young
680 // regions will fit in the target pause time. If not, we'll do
681 // a binary search between min_young_length and max_young_length.
682 if (predict_will_fit(max_young_length, base_time_ms,
683 base_free_regions, target_pause_time_ms)) {
684 // The maximum young length will fit into the target pause time.
685 // We are done so set min young length to the maximum length (as
686 // the result is assumed to be returned in min_young_length).
687 min_young_length = max_young_length;
688 } else {
689 // The maximum possible number of young regions will not fit within
690 // the target pause time so we'll search for the optimal
691 // length. The loop invariants are:
692 //
693 // min_young_length < max_young_length
694 // min_young_length is known to fit into the target pause time
695 // max_young_length is known not to fit into the target pause time
696 //
697 // Going into the loop we know the above hold as we've just
698 // checked them. Every time around the loop we check whether
699 // the middle value between min_young_length and
700 // max_young_length fits into the target pause time. If it
701 // does, it becomes the new min. If it doesn't, it becomes
702 // the new max. This way we maintain the loop invariants.
703
704 assert(min_young_length < max_young_length, "invariant");
705 uint diff = (max_young_length - min_young_length) / 2;
706 while (diff > 0) {
707 uint young_length = min_young_length + diff;
708 if (predict_will_fit(young_length, base_time_ms,
709 base_free_regions, target_pause_time_ms)) {
710 min_young_length = young_length;
711 } else {
712 max_young_length = young_length;
713 }
714 assert(min_young_length < max_young_length, "invariant");
715 diff = (max_young_length - min_young_length) / 2;
716 }
717 // The results is min_young_length which, according to the
718 // loop invariants, should fit within the target pause time.
719
720 // These are the post-conditions of the binary search above:
721 assert(min_young_length < max_young_length,
722 "otherwise we should have discovered that max_young_length "
723 "fits into the pause target and not done the binary search");
724 assert(predict_will_fit(min_young_length, base_time_ms,
725 base_free_regions, target_pause_time_ms),
726 "min_young_length, the result of the binary search, should "
727 "fit into the pause target");
728 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
729 base_free_regions, target_pause_time_ms),
730 "min_young_length, the result of the binary search, should be "
731 "optimal, so no larger length should fit into the pause target");
732 }
733 } else {
734 // Even the minimum length doesn't fit into the pause time
735 // target, return it as the result nevertheless.
736 }
737 return base_min_length + min_young_length;
738 }
739
740 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
741 double survivor_regions_evac_time = 0.0;
742 for (HeapRegion * r = _recorded_survivor_head;
743 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
744 r = r->get_next_young_region()) {
745 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
746 }
747 return survivor_regions_evac_time;
748 }
749
750 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
751 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
752
753 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
754 if (rs_lengths > _rs_lengths_prediction) {
755 // add 10% to avoid having to recalculate often
756 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
757 update_young_list_target_length(rs_lengths_prediction);
758 }
759 }
760
761
762
763 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
764 bool is_tlab,
765 bool* gc_overhead_limit_was_exceeded) {
766 guarantee(false, "Not using this policy feature yet.");
767 return NULL;
768 }
769
770 // This method controls how a collector handles one or more
771 // of its generations being fully allocated.
772 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
773 bool is_tlab) {
774 guarantee(false, "Not using this policy feature yet.");
775 return NULL;
776 }
777
778
779 #ifndef PRODUCT
780 bool G1CollectorPolicy::verify_young_ages() {
781 HeapRegion* head = _g1->young_list()->first_region();
782 return
783 verify_young_ages(head, _short_lived_surv_rate_group);
784 // also call verify_young_ages on any additional surv rate groups
785 }
786
787 bool
788 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
789 SurvRateGroup *surv_rate_group) {
790 guarantee( surv_rate_group != NULL, "pre-condition" );
791
792 const char* name = surv_rate_group->name();
793 bool ret = true;
794 int prev_age = -1;
795
796 for (HeapRegion* curr = head;
797 curr != NULL;
798 curr = curr->get_next_young_region()) {
799 SurvRateGroup* group = curr->surv_rate_group();
800 if (group == NULL && !curr->is_survivor()) {
801 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
802 ret = false;
803 }
804
805 if (surv_rate_group == group) {
806 int age = curr->age_in_surv_rate_group();
807
808 if (age < 0) {
809 gclog_or_tty->print_cr("## %s: encountered negative age", name);
810 ret = false;
811 }
812
813 if (age <= prev_age) {
814 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
815 "(%d, %d)", name, age, prev_age);
816 ret = false;
817 }
818 prev_age = age;
819 }
820 }
821
822 return ret;
823 }
824 #endif // PRODUCT
825
826 void G1CollectorPolicy::record_full_collection_start() {
827 _cur_collection_start_sec = os::elapsedTime();
828 // Release the future to-space so that it is available for compaction into.
829 _g1->set_full_collection();
830 }
831
832 void G1CollectorPolicy::record_full_collection_end() {
833 // Consider this like a collection pause for the purposes of allocation
834 // since last pause.
835 double end_sec = os::elapsedTime();
836 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
837 double full_gc_time_ms = full_gc_time_sec * 1000.0;
838
839 _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
840
841 update_recent_gc_times(end_sec, full_gc_time_ms);
842
843 _g1->clear_full_collection();
844
845 // "Nuke" the heuristics that control the young/mixed GC
846 // transitions and make sure we start with young GCs after the Full GC.
847 set_gcs_are_young(true);
848 _last_young_gc = false;
849 clear_initiate_conc_mark_if_possible();
850 clear_during_initial_mark_pause();
851 _in_marking_window = false;
852 _in_marking_window_im = false;
853
854 _short_lived_surv_rate_group->start_adding_regions();
855 // also call this on any additional surv rate groups
856
857 record_survivor_regions(0, NULL, NULL);
858
859 _free_regions_at_end_of_collection = _g1->free_regions();
860 // Reset survivors SurvRateGroup.
861 _survivor_surv_rate_group->reset();
862 update_young_list_target_length();
863 _collectionSetChooser->clear();
864 }
865
866 void G1CollectorPolicy::record_stop_world_start() {
867 _stop_world_start = os::elapsedTime();
868 }
869
870 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
871 size_t start_used) {
872 if (G1Log::finer()) {
873 gclog_or_tty->stamp(PrintGCTimeStamps);
874 gclog_or_tty->print("[%s", (const char*)GCCauseString("GC pause", _g1->gc_cause())
875 .append(gcs_are_young() ? " (young)" : " (mixed)"));
876 }
877
878 // We only need to do this here as the policy will only be applied
879 // to the GC we're about to start. so, no point is calculating this
880 // every time we calculate / recalculate the target young length.
881 update_survivors_policy();
882
883 assert(_g1->used() == _g1->recalculate_used(),
884 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
885 _g1->used(), _g1->recalculate_used()));
886
887 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
888 _trace_gen0_time_data.record_start_collection(s_w_t_ms);
889 _stop_world_start = 0.0;
890
891 _cur_collection_start_sec = start_time_sec;
892 _cur_collection_pause_used_at_start_bytes = start_used;
893 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
894 _pending_cards = _g1->pending_card_num();
895 _max_pending_cards = _g1->max_pending_card_num();
896
897 _bytes_in_collection_set_before_gc = 0;
898 _bytes_copied_during_gc = 0;
899
900 YoungList* young_list = _g1->young_list();
901 _eden_bytes_before_gc = young_list->eden_used_bytes();
902 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
903 _capacity_before_gc = _g1->capacity();
904
905 #ifdef DEBUG
906 // initialise these to something well known so that we can spot
907 // if they are not set properly
908
909 for (int i = 0; i < _parallel_gc_threads; ++i) {
910 _par_last_gc_worker_start_times_ms[i] = -1234.0;
911 _par_last_ext_root_scan_times_ms[i] = -1234.0;
912 _par_last_satb_filtering_times_ms[i] = -1234.0;
913 _par_last_update_rs_times_ms[i] = -1234.0;
914 _par_last_update_rs_processed_buffers[i] = -1234.0;
915 _par_last_scan_rs_times_ms[i] = -1234.0;
916 _par_last_obj_copy_times_ms[i] = -1234.0;
917 _par_last_termination_times_ms[i] = -1234.0;
918 _par_last_termination_attempts[i] = -1234.0;
919 _par_last_gc_worker_end_times_ms[i] = -1234.0;
920 _par_last_gc_worker_times_ms[i] = -1234.0;
921 _par_last_gc_worker_other_times_ms[i] = -1234.0;
922 }
923 #endif
924
925 // This is initialized to zero here and is set during the evacuation
926 // pause if we actually waited for the root region scanning to finish.
927 _root_region_scan_wait_time_ms = 0.0;
928
929 _last_gc_was_young = false;
930
931 // do that for any other surv rate groups
932 _short_lived_surv_rate_group->stop_adding_regions();
933 _survivors_age_table.clear();
934
935 assert( verify_young_ages(), "region age verification" );
936 }
937
938 void G1CollectorPolicy::record_concurrent_mark_init_end(double
939 mark_init_elapsed_time_ms) {
940 _during_marking = true;
941 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
942 clear_during_initial_mark_pause();
943 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
944 }
945
946 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
947 _mark_remark_start_sec = os::elapsedTime();
948 _during_marking = false;
949 }
950
951 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
952 double end_time_sec = os::elapsedTime();
953 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
954 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
955 _cur_mark_stop_world_time_ms += elapsed_time_ms;
956 _prev_collection_pause_end_ms += elapsed_time_ms;
957
958 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
959 }
960
961 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
962 _mark_cleanup_start_sec = os::elapsedTime();
963 }
964
965 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
966 _last_young_gc = true;
967 _in_marking_window = false;
968 }
969
970 void G1CollectorPolicy::record_concurrent_pause() {
971 if (_stop_world_start > 0.0) {
972 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
973 _trace_gen0_time_data.record_yield_time(yield_ms);
974 }
975 }
976
977 void G1CollectorPolicy::record_concurrent_pause_end() {
978 }
979
980 template<class T>
981 T sum_of(T* sum_arr, int start, int n, int N) {
982 T sum = (T)0;
983 for (int i = 0; i < n; i++) {
984 int j = (start + i) % N;
985 sum += sum_arr[j];
986 }
987 return sum;
988 }
989
990 void G1CollectorPolicy::print_par_stats(int level,
991 const char* str,
992 double* data,
993 bool showDecimals) {
994 double min = data[0], max = data[0];
995 double total = 0.0;
996 LineBuffer buf(level);
997 buf.append("[%s (ms):", str);
998 for (uint i = 0; i < no_of_gc_threads(); ++i) {
999 double val = data[i];
1000 if (val < min)
1001 min = val;
1002 if (val > max)
1003 max = val;
1004 total += val;
1005 if (G1Log::finest()) {
1006 if (showDecimals) {
1007 buf.append(" %.1lf", val);
1008 } else {
1009 buf.append(" %d", (int)val);
1010 }
1011 }
1012 }
1013
1014 if (G1Log::finest()) {
1015 buf.append_and_print_cr("");
1016 }
1017 double avg = total / (double) no_of_gc_threads();
1018 if (showDecimals) {
1019 buf.append_and_print_cr(" Min: %.1lf, Avg: %.1lf, Max: %.1lf, Diff: %.1lf, Sum: %.1lf]",
1020 min, avg, max, max - min, total);
1021 } else {
1022 buf.append_and_print_cr(" Min: %d, Avg: %d, Max: %d, Diff: %d, Sum: %d]",
1023 (int)min, (int)avg, (int)max, (int)max - (int)min, (int)total);
1024 }
1025 }
1026
1027 void G1CollectorPolicy::print_stats(int level,
1028 const char* str,
1029 double value) {
1030 LineBuffer(level).append_and_print_cr("[%s: %.1lf ms]", str, value);
1031 }
1032
1033 void G1CollectorPolicy::print_stats(int level,
1034 const char* str,
1035 double value,
1036 int workers) {
1037 LineBuffer(level).append_and_print_cr("[%s: %.1lf ms, GC Workers: %d]", str, value, workers);
1038 }
1039
1040 void G1CollectorPolicy::print_stats(int level,
1041 const char* str,
1042 int value) {
1043 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1044 }
1045
1046 double G1CollectorPolicy::avg_value(double* data) {
1047 if (G1CollectedHeap::use_parallel_gc_threads()) {
1048 double ret = 0.0;
1049 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1050 ret += data[i];
1051 }
1052 return ret / (double) no_of_gc_threads();
1053 } else {
1054 return data[0];
1055 }
1056 }
1057
1058 double G1CollectorPolicy::max_value(double* data) {
1059 if (G1CollectedHeap::use_parallel_gc_threads()) {
1060 double ret = data[0];
1061 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1062 if (data[i] > ret) {
1063 ret = data[i];
1064 }
1065 }
1066 return ret;
1067 } else {
1068 return data[0];
1069 }
1070 }
1071
1072 double G1CollectorPolicy::sum_of_values(double* data) {
1073 if (G1CollectedHeap::use_parallel_gc_threads()) {
1074 double sum = 0.0;
1075 for (uint i = 0; i < no_of_gc_threads(); i++) {
1076 sum += data[i];
1077 }
1078 return sum;
1079 } else {
1080 return data[0];
1081 }
1082 }
1083
1084 double G1CollectorPolicy::max_sum(double* data1, double* data2) {
1085 double ret = data1[0] + data2[0];
1086
1087 if (G1CollectedHeap::use_parallel_gc_threads()) {
1088 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1089 double data = data1[i] + data2[i];
1090 if (data > ret) {
1091 ret = data;
1092 }
1093 }
1094 }
1095 return ret;
1096 }
1097
1098 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
1099 if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
1100 return false;
1101 }
1102
1103 size_t marking_initiating_used_threshold =
1104 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1105 size_t cur_used_bytes = _g1->non_young_capacity_bytes();
1106 size_t alloc_byte_size = alloc_word_size * HeapWordSize;
1107
1108 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
1109 if (gcs_are_young()) {
1110 ergo_verbose5(ErgoConcCycles,
1111 "request concurrent cycle initiation",
1112 ergo_format_reason("occupancy higher than threshold")
1113 ergo_format_byte("occupancy")
1114 ergo_format_byte("allocation request")
1115 ergo_format_byte_perc("threshold")
1116 ergo_format_str("source"),
1117 cur_used_bytes,
1118 alloc_byte_size,
1119 marking_initiating_used_threshold,
1120 (double) InitiatingHeapOccupancyPercent,
1121 source);
1122 return true;
1123 } else {
1124 ergo_verbose5(ErgoConcCycles,
1125 "do not request concurrent cycle initiation",
1126 ergo_format_reason("still doing mixed collections")
1127 ergo_format_byte("occupancy")
1128 ergo_format_byte("allocation request")
1129 ergo_format_byte_perc("threshold")
1130 ergo_format_str("source"),
1131 cur_used_bytes,
1132 alloc_byte_size,
1133 marking_initiating_used_threshold,
1134 (double) InitiatingHeapOccupancyPercent,
1135 source);
1136 }
1137 }
1138
1139 return false;
1140 }
1141
1142 // Anything below that is considered to be zero
1143 #define MIN_TIMER_GRANULARITY 0.0000001
1144
1145 void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
1146 double end_time_sec = os::elapsedTime();
1147 double elapsed_ms = _last_pause_time_ms;
1148 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1149 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1150 "otherwise, the subtraction below does not make sense");
1151 size_t rs_size =
1152 _cur_collection_pause_used_regions_at_start - cset_region_length();
1153 size_t cur_used_bytes = _g1->used();
1154 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1155 bool last_pause_included_initial_mark = false;
1156 bool update_stats = !_g1->evacuation_failed();
1157 set_no_of_gc_threads(no_of_gc_threads);
1158
1159 #ifndef PRODUCT
1160 if (G1YoungSurvRateVerbose) {
1161 gclog_or_tty->print_cr("");
1162 _short_lived_surv_rate_group->print();
1163 // do that for any other surv rate groups too
1164 }
1165 #endif // PRODUCT
1166
1167 last_pause_included_initial_mark = during_initial_mark_pause();
1168 if (last_pause_included_initial_mark) {
1169 record_concurrent_mark_init_end(0.0);
1170 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
1171 // Note: this might have already been set, if during the last
1172 // pause we decided to start a cycle but at the beginning of
1173 // this pause we decided to postpone it. That's OK.
1174 set_initiate_conc_mark_if_possible();
1175 }
1176
1177 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1178 end_time_sec, false);
1179
1180 size_t freed_bytes =
1181 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1182 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1183
1184 double survival_fraction =
1185 (double)surviving_bytes/
1186 (double)_collection_set_bytes_used_before;
1187
1188 // These values are used to update the summary information that is
1189 // displayed when TraceGen0Time is enabled, and are output as part
1190 // of the "finer" output, in the non-parallel case.
1191
1192 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1193 double satb_filtering_time = avg_value(_par_last_satb_filtering_times_ms);
1194 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1195 double update_rs_processed_buffers =
1196 sum_of_values(_par_last_update_rs_processed_buffers);
1197 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1198 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1199 double termination_time = avg_value(_par_last_termination_times_ms);
1200
1201 double known_time = ext_root_scan_time +
1202 satb_filtering_time +
1203 update_rs_time +
1204 scan_rs_time +
1205 obj_copy_time;
1206
1207 double other_time_ms = elapsed_ms;
1208
1209 // Subtract the root region scanning wait time. It's initialized to
1210 // zero at the start of the pause.
1211 other_time_ms -= _root_region_scan_wait_time_ms;
1212
1213 if (parallel) {
1214 other_time_ms -= _cur_collection_par_time_ms;
1215 } else {
1216 other_time_ms -= known_time;
1217 }
1218
1219 // Now subtract the time taken to fix up roots in generated code
1220 other_time_ms -= _cur_collection_code_root_fixup_time_ms;
1221
1222 // Subtract the time taken to clean the card table from the
1223 // current value of "other time"
1224 other_time_ms -= _cur_clear_ct_time_ms;
1225
1226 // TraceGen0Time and TraceGen1Time summary info updating.
1227
1228 if (update_stats) {
1229 double parallel_known_time = known_time + termination_time;
1230 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1231
1232 _trace_gen0_time_data.record_end_collection(
1233 elapsed_ms, other_time_ms, _root_region_scan_wait_time_ms, _cur_collection_par_time_ms,
1234 ext_root_scan_time, satb_filtering_time, update_rs_time, scan_rs_time, obj_copy_time,
1235 termination_time, parallel_other_time, _cur_clear_ct_time_ms);
1236
1237 // this is where we update the allocation rate of the application
1238 double app_time_ms =
1239 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1240 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1241 // This usually happens due to the timer not having the required
1242 // granularity. Some Linuxes are the usual culprits.
1243 // We'll just set it to something (arbitrarily) small.
1244 app_time_ms = 1.0;
1245 }
1246 // We maintain the invariant that all objects allocated by mutator
1247 // threads will be allocated out of eden regions. So, we can use
1248 // the eden region number allocated since the previous GC to
1249 // calculate the application's allocate rate. The only exception
1250 // to that is humongous objects that are allocated separately. But
1251 // given that humongous object allocations do not really affect
1252 // either the pause's duration nor when the next pause will take
1253 // place we can safely ignore them here.
1254 uint regions_allocated = eden_cset_region_length();
1255 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1256 _alloc_rate_ms_seq->add(alloc_rate_ms);
1257
1258 double interval_ms =
1259 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1260 update_recent_gc_times(end_time_sec, elapsed_ms);
1261 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1262 if (recent_avg_pause_time_ratio() < 0.0 ||
1263 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1264 #ifndef PRODUCT
1265 // Dump info to allow post-facto debugging
1266 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1267 gclog_or_tty->print_cr("-------------------------------------------");
1268 gclog_or_tty->print_cr("Recent GC Times (ms):");
1269 _recent_gc_times_ms->dump();
1270 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1271 _recent_prev_end_times_for_all_gcs_sec->dump();
1272 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1273 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1274 // In debug mode, terminate the JVM if the user wants to debug at this point.
1275 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1276 #endif // !PRODUCT
1277 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1278 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1279 if (_recent_avg_pause_time_ratio < 0.0) {
1280 _recent_avg_pause_time_ratio = 0.0;
1281 } else {
1282 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1283 _recent_avg_pause_time_ratio = 1.0;
1284 }
1285 }
1286 }
1287
1288 if (G1Log::finer()) {
1289 bool print_marking_info =
1290 _g1->mark_in_progress() && !last_pause_included_initial_mark;
1291
1292 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1293 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1294 elapsed_ms / 1000.0);
1295
1296 if (_root_region_scan_wait_time_ms > 0.0) {
1297 print_stats(1, "Root Region Scan Waiting", _root_region_scan_wait_time_ms);
1298 }
1299 if (parallel) {
1300 print_stats(1, "Parallel Time", _cur_collection_par_time_ms, no_of_gc_threads);
1301 print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
1302 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1303 if (print_marking_info) {
1304 print_par_stats(2, "SATB Filtering", _par_last_satb_filtering_times_ms);
1305 }
1306 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1307 if (G1Log::finest()) {
1308 print_par_stats(3, "Processed Buffers", _par_last_update_rs_processed_buffers,
1309 false /* showDecimals */);
1310 }
1311 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1312 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1313 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1314 if (G1Log::finest()) {
1315 print_par_stats(3, "Termination Attempts", _par_last_termination_attempts,
1316 false /* showDecimals */);
1317 }
1318
1319 for (int i = 0; i < _parallel_gc_threads; i++) {
1320 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] -
1321 _par_last_gc_worker_start_times_ms[i];
1322
1323 double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
1324 _par_last_satb_filtering_times_ms[i] +
1325 _par_last_update_rs_times_ms[i] +
1326 _par_last_scan_rs_times_ms[i] +
1327 _par_last_obj_copy_times_ms[i] +
1328 _par_last_termination_times_ms[i];
1329
1330 _par_last_gc_worker_other_times_ms[i] = _par_last_gc_worker_times_ms[i] -
1331 worker_known_time;
1332 }
1333
1334 print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
1335 print_par_stats(2, "GC Worker Total", _par_last_gc_worker_times_ms);
1336 print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
1337 } else {
1338 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1339 if (print_marking_info) {
1340 print_stats(1, "SATB Filtering", satb_filtering_time);
1341 }
1342 print_stats(1, "Update RS", update_rs_time);
1343 if (G1Log::finest()) {
1344 print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
1345 }
1346 print_stats(1, "Scan RS", scan_rs_time);
1347 print_stats(1, "Object Copying", obj_copy_time);
1348 }
1349 print_stats(1, "Code Root Fixup", _cur_collection_code_root_fixup_time_ms);
1350 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1351 #ifndef PRODUCT
1352 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1353 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1354 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1355 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1356 if (_num_cc_clears > 0) {
1357 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1358 }
1359 #endif
1360 print_stats(1, "Other", other_time_ms);
1361 print_stats(2, "Choose CSet",
1362 (_recorded_young_cset_choice_time_ms +
1363 _recorded_non_young_cset_choice_time_ms));
1364 print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
1365 print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
1366 print_stats(2, "Free CSet",
1367 (_recorded_young_free_cset_time_ms +
1368 _recorded_non_young_free_cset_time_ms));
1369 }
1370
1371 bool new_in_marking_window = _in_marking_window;
1372 bool new_in_marking_window_im = false;
1373 if (during_initial_mark_pause()) {
1374 new_in_marking_window = true;
1375 new_in_marking_window_im = true;
1376 }
1377
1378 if (_last_young_gc) {
1379 // This is supposed to to be the "last young GC" before we start
1380 // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1381
1382 if (!last_pause_included_initial_mark) {
1383 if (next_gc_should_be_mixed("start mixed GCs",
1384 "do not start mixed GCs")) {
1385 set_gcs_are_young(false);
1386 }
1387 } else {
1388 ergo_verbose0(ErgoMixedGCs,
1389 "do not start mixed GCs",
1390 ergo_format_reason("concurrent cycle is about to start"));
1391 }
1392 _last_young_gc = false;
1393 }
1394
1395 if (!_last_gc_was_young) {
1396 // This is a mixed GC. Here we decide whether to continue doing
1397 // mixed GCs or not.
1398
1399 if (!next_gc_should_be_mixed("continue mixed GCs",
1400 "do not continue mixed GCs")) {
1401 set_gcs_are_young(true);
1402 }
1403 }
1404
1405 _short_lived_surv_rate_group->start_adding_regions();
1406 // do that for any other surv rate groupsx
1407
1408 if (update_stats) {
1409 double pause_time_ms = elapsed_ms;
1410
1411 size_t diff = 0;
1412 if (_max_pending_cards >= _pending_cards) {
1413 diff = _max_pending_cards - _pending_cards;
1414 }
1415 _pending_card_diff_seq->add((double) diff);
1416
1417 double cost_per_card_ms = 0.0;
1418 if (_pending_cards > 0) {
1419 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1420 _cost_per_card_ms_seq->add(cost_per_card_ms);
1421 }
1422
1423 size_t cards_scanned = _g1->cards_scanned();
1424
1425 double cost_per_entry_ms = 0.0;
1426 if (cards_scanned > 10) {
1427 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1428 if (_last_gc_was_young) {
1429 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1430 } else {
1431 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1432 }
1433 }
1434
1435 if (_max_rs_lengths > 0) {
1436 double cards_per_entry_ratio =
1437 (double) cards_scanned / (double) _max_rs_lengths;
1438 if (_last_gc_was_young) {
1439 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1440 } else {
1441 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1442 }
1443 }
1444
1445 // This is defensive. For a while _max_rs_lengths could get
1446 // smaller than _recorded_rs_lengths which was causing
1447 // rs_length_diff to get very large and mess up the RSet length
1448 // predictions. The reason was unsafe concurrent updates to the
1449 // _inc_cset_recorded_rs_lengths field which the code below guards
1450 // against (see CR 7118202). This bug has now been fixed (see CR
1451 // 7119027). However, I'm still worried that
1452 // _inc_cset_recorded_rs_lengths might still end up somewhat
1453 // inaccurate. The concurrent refinement thread calculates an
1454 // RSet's length concurrently with other CR threads updating it
1455 // which might cause it to calculate the length incorrectly (if,
1456 // say, it's in mid-coarsening). So I'll leave in the defensive
1457 // conditional below just in case.
1458 size_t rs_length_diff = 0;
1459 if (_max_rs_lengths > _recorded_rs_lengths) {
1460 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1461 }
1462 _rs_length_diff_seq->add((double) rs_length_diff);
1463
1464 size_t copied_bytes = surviving_bytes;
1465 double cost_per_byte_ms = 0.0;
1466 if (copied_bytes > 0) {
1467 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1468 if (_in_marking_window) {
1469 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1470 } else {
1471 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1472 }
1473 }
1474
1475 double all_other_time_ms = pause_time_ms -
1476 (update_rs_time + scan_rs_time + obj_copy_time + termination_time);
1477
1478 double young_other_time_ms = 0.0;
1479 if (young_cset_region_length() > 0) {
1480 young_other_time_ms =
1481 _recorded_young_cset_choice_time_ms +
1482 _recorded_young_free_cset_time_ms;
1483 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1484 (double) young_cset_region_length());
1485 }
1486 double non_young_other_time_ms = 0.0;
1487 if (old_cset_region_length() > 0) {
1488 non_young_other_time_ms =
1489 _recorded_non_young_cset_choice_time_ms +
1490 _recorded_non_young_free_cset_time_ms;
1491
1492 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1493 (double) old_cset_region_length());
1494 }
1495
1496 double constant_other_time_ms = all_other_time_ms -
1497 (young_other_time_ms + non_young_other_time_ms);
1498 _constant_other_time_ms_seq->add(constant_other_time_ms);
1499
1500 double survival_ratio = 0.0;
1501 if (_bytes_in_collection_set_before_gc > 0) {
1502 survival_ratio = (double) _bytes_copied_during_gc /
1503 (double) _bytes_in_collection_set_before_gc;
1504 }
1505
1506 _pending_cards_seq->add((double) _pending_cards);
1507 _rs_lengths_seq->add((double) _max_rs_lengths);
1508 }
1509
1510 _in_marking_window = new_in_marking_window;
1511 _in_marking_window_im = new_in_marking_window_im;
1512 _free_regions_at_end_of_collection = _g1->free_regions();
1513 update_young_list_target_length();
1514
1515 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1516 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1517 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1518
1519 _collectionSetChooser->verify();
1520 }
1521
1522 #define EXT_SIZE_FORMAT "%.1f%s"
1523 #define EXT_SIZE_PARAMS(bytes) \
1524 byte_size_in_proper_unit((double)(bytes)), \
1525 proper_unit_for_byte_size((bytes))
1526
1527 void G1CollectorPolicy::print_heap_transition() {
1528 if (G1Log::finer()) {
1529 YoungList* young_list = _g1->young_list();
1530 size_t eden_bytes = young_list->eden_used_bytes();
1531 size_t survivor_bytes = young_list->survivor_used_bytes();
1532 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1533 size_t used = _g1->used();
1534 size_t capacity = _g1->capacity();
1535 size_t eden_capacity =
1536 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1537
1538 gclog_or_tty->print_cr(
1539 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1540 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1541 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1542 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1543 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1544 EXT_SIZE_PARAMS(_prev_eden_capacity),
1545 EXT_SIZE_PARAMS(eden_bytes),
1546 EXT_SIZE_PARAMS(eden_capacity),
1547 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1548 EXT_SIZE_PARAMS(survivor_bytes),
1549 EXT_SIZE_PARAMS(used_before_gc),
1550 EXT_SIZE_PARAMS(_capacity_before_gc),
1551 EXT_SIZE_PARAMS(used),
1552 EXT_SIZE_PARAMS(capacity));
1553
1554 _prev_eden_capacity = eden_capacity;
1555 } else if (G1Log::fine()) {
1556 _g1->print_size_transition(gclog_or_tty,
1557 _cur_collection_pause_used_at_start_bytes,
1558 _g1->used(), _g1->capacity());
1559 }
1560 }
1561
1562 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1563 double update_rs_processed_buffers,
1564 double goal_ms) {
1565 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1566 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1567
1568 if (G1UseAdaptiveConcRefinement) {
1569 const int k_gy = 3, k_gr = 6;
1570 const double inc_k = 1.1, dec_k = 0.9;
1571
1572 int g = cg1r->green_zone();
1573 if (update_rs_time > goal_ms) {
1574 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1575 } else {
1576 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1577 g = (int)MAX2(g * inc_k, g + 1.0);
1578 }
1579 }
1580 // Change the refinement threads params
1581 cg1r->set_green_zone(g);
1582 cg1r->set_yellow_zone(g * k_gy);
1583 cg1r->set_red_zone(g * k_gr);
1584 cg1r->reinitialize_threads();
1585
1586 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1587 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1588 cg1r->yellow_zone());
1589 // Change the barrier params
1590 dcqs.set_process_completed_threshold(processing_threshold);
1591 dcqs.set_max_completed_queue(cg1r->red_zone());
1592 }
1593
1594 int curr_queue_size = dcqs.completed_buffers_num();
1595 if (curr_queue_size >= cg1r->yellow_zone()) {
1596 dcqs.set_completed_queue_padding(curr_queue_size);
1597 } else {
1598 dcqs.set_completed_queue_padding(0);
1599 }
1600 dcqs.notify_if_necessary();
1601 }
1602
1603 double
1604 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1605 size_t rs_length = predict_rs_length_diff();
1606 size_t card_num;
1607 if (gcs_are_young()) {
1608 card_num = predict_young_card_num(rs_length);
1609 } else {
1610 card_num = predict_non_young_card_num(rs_length);
1611 }
1612 return predict_base_elapsed_time_ms(pending_cards, card_num);
1613 }
1614
1615 double
1616 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1617 size_t scanned_cards) {
1618 return
1619 predict_rs_update_time_ms(pending_cards) +
1620 predict_rs_scan_time_ms(scanned_cards) +
1621 predict_constant_other_time_ms();
1622 }
1623
1624 double
1625 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1626 bool young) {
1627 size_t rs_length = hr->rem_set()->occupied();
1628 size_t card_num;
1629 if (gcs_are_young()) {
1630 card_num = predict_young_card_num(rs_length);
1631 } else {
1632 card_num = predict_non_young_card_num(rs_length);
1633 }
1634 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1635
1636 double region_elapsed_time_ms =
1637 predict_rs_scan_time_ms(card_num) +
1638 predict_object_copy_time_ms(bytes_to_copy);
1639
1640 if (young)
1641 region_elapsed_time_ms += predict_young_other_time_ms(1);
1642 else
1643 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1644
1645 return region_elapsed_time_ms;
1646 }
1647
1648 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1649 size_t bytes_to_copy;
1650 if (hr->is_marked())
1651 bytes_to_copy = hr->max_live_bytes();
1652 else {
1653 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1654 int age = hr->age_in_surv_rate_group();
1655 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1656 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1657 }
1658 return bytes_to_copy;
1659 }
1660
1661 void
1662 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1663 uint survivor_cset_region_length) {
1664 _eden_cset_region_length = eden_cset_region_length;
1665 _survivor_cset_region_length = survivor_cset_region_length;
1666 _old_cset_region_length = 0;
1667 }
1668
1669 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1670 _recorded_rs_lengths = rs_lengths;
1671 }
1672
1673 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1674 double elapsed_ms) {
1675 _recent_gc_times_ms->add(elapsed_ms);
1676 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1677 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1678 }
1679
1680 size_t G1CollectorPolicy::expansion_amount() {
1681 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1682 double threshold = _gc_overhead_perc;
1683 if (recent_gc_overhead > threshold) {
1684 // We will double the existing space, or take
1685 // G1ExpandByPercentOfAvailable % of the available expansion
1686 // space, whichever is smaller, bounded below by a minimum
1687 // expansion (unless that's all that's left.)
1688 const size_t min_expand_bytes = 1*M;
1689 size_t reserved_bytes = _g1->max_capacity();
1690 size_t committed_bytes = _g1->capacity();
1691 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1692 size_t expand_bytes;
1693 size_t expand_bytes_via_pct =
1694 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1695 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1696 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1697 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1698
1699 ergo_verbose5(ErgoHeapSizing,
1700 "attempt heap expansion",
1701 ergo_format_reason("recent GC overhead higher than "
1702 "threshold after GC")
1703 ergo_format_perc("recent GC overhead")
1704 ergo_format_perc("threshold")
1705 ergo_format_byte("uncommitted")
1706 ergo_format_byte_perc("calculated expansion amount"),
1707 recent_gc_overhead, threshold,
1708 uncommitted_bytes,
1709 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1710
1711 return expand_bytes;
1712 } else {
1713 return 0;
1714 }
1715 }
1716
1717 class CountCSClosure: public HeapRegionClosure {
1718 G1CollectorPolicy* _g1_policy;
1719 public:
1720 CountCSClosure(G1CollectorPolicy* g1_policy) :
1721 _g1_policy(g1_policy) {}
1722 bool doHeapRegion(HeapRegion* r) {
1723 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
1724 return false;
1725 }
1726 };
1727
1728 void G1CollectorPolicy::count_CS_bytes_used() {
1729 CountCSClosure cs_closure(this);
1730 _g1->collection_set_iterate(&cs_closure);
1731 }
1732
1733 void G1CollectorPolicy::print_tracing_info() const {
1734 _trace_gen0_time_data.print();
1735 _trace_gen1_time_data.print();
1736 }
1737
1738 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1739 #ifndef PRODUCT
1740 _short_lived_surv_rate_group->print_surv_rate_summary();
1741 // add this call for any other surv rate groups
1742 #endif // PRODUCT
1743 }
1744
1745 #ifndef PRODUCT
1746 // for debugging, bit of a hack...
1747 static char*
1748 region_num_to_mbs(int length) {
1749 static char buffer[64];
1750 double bytes = (double) (length * HeapRegion::GrainBytes);
1751 double mbs = bytes / (double) (1024 * 1024);
1752 sprintf(buffer, "%7.2lfMB", mbs);
1753 return buffer;
1754 }
1755 #endif // PRODUCT
1756
1757 uint G1CollectorPolicy::max_regions(int purpose) {
1758 switch (purpose) {
1759 case GCAllocForSurvived:
1760 return _max_survivor_regions;
1761 case GCAllocForTenured:
1762 return REGIONS_UNLIMITED;
1763 default:
1764 ShouldNotReachHere();
1765 return REGIONS_UNLIMITED;
1766 };
1767 }
1768
1769 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1770 uint expansion_region_num = 0;
1771 if (GCLockerEdenExpansionPercent > 0) {
1772 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1773 double expansion_region_num_d = perc * (double) _young_list_target_length;
1774 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1775 // less than 1.0) we'll get 1.
1776 expansion_region_num = (uint) ceil(expansion_region_num_d);
1777 } else {
1778 assert(expansion_region_num == 0, "sanity");
1779 }
1780 _young_list_max_length = _young_list_target_length + expansion_region_num;
1781 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1782 }
1783
1784 // Calculates survivor space parameters.
1785 void G1CollectorPolicy::update_survivors_policy() {
1786 double max_survivor_regions_d =
1787 (double) _young_list_target_length / (double) SurvivorRatio;
1788 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1789 // smaller than 1.0) we'll get 1.
1790 _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1791
1792 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1793 HeapRegion::GrainWords * _max_survivor_regions);
1794 }
1795
1796 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1797 GCCause::Cause gc_cause) {
1798 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1799 if (!during_cycle) {
1800 ergo_verbose1(ErgoConcCycles,
1801 "request concurrent cycle initiation",
1802 ergo_format_reason("requested by GC cause")
1803 ergo_format_str("GC cause"),
1804 GCCause::to_string(gc_cause));
1805 set_initiate_conc_mark_if_possible();
1806 return true;
1807 } else {
1808 ergo_verbose1(ErgoConcCycles,
1809 "do not request concurrent cycle initiation",
1810 ergo_format_reason("concurrent cycle already in progress")
1811 ergo_format_str("GC cause"),
1812 GCCause::to_string(gc_cause));
1813 return false;
1814 }
1815 }
1816
1817 void
1818 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1819 // We are about to decide on whether this pause will be an
1820 // initial-mark pause.
1821
1822 // First, during_initial_mark_pause() should not be already set. We
1823 // will set it here if we have to. However, it should be cleared by
1824 // the end of the pause (it's only set for the duration of an
1825 // initial-mark pause).
1826 assert(!during_initial_mark_pause(), "pre-condition");
1827
1828 if (initiate_conc_mark_if_possible()) {
1829 // We had noticed on a previous pause that the heap occupancy has
1830 // gone over the initiating threshold and we should start a
1831 // concurrent marking cycle. So we might initiate one.
1832
1833 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1834 if (!during_cycle) {
1835 // The concurrent marking thread is not "during a cycle", i.e.,
1836 // it has completed the last one. So we can go ahead and
1837 // initiate a new cycle.
1838
1839 set_during_initial_mark_pause();
1840 // We do not allow mixed GCs during marking.
1841 if (!gcs_are_young()) {
1842 set_gcs_are_young(true);
1843 ergo_verbose0(ErgoMixedGCs,
1844 "end mixed GCs",
1845 ergo_format_reason("concurrent cycle is about to start"));
1846 }
1847
1848 // And we can now clear initiate_conc_mark_if_possible() as
1849 // we've already acted on it.
1850 clear_initiate_conc_mark_if_possible();
1851
1852 ergo_verbose0(ErgoConcCycles,
1853 "initiate concurrent cycle",
1854 ergo_format_reason("concurrent cycle initiation requested"));
1855 } else {
1856 // The concurrent marking thread is still finishing up the
1857 // previous cycle. If we start one right now the two cycles
1858 // overlap. In particular, the concurrent marking thread might
1859 // be in the process of clearing the next marking bitmap (which
1860 // we will use for the next cycle if we start one). Starting a
1861 // cycle now will be bad given that parts of the marking
1862 // information might get cleared by the marking thread. And we
1863 // cannot wait for the marking thread to finish the cycle as it
1864 // periodically yields while clearing the next marking bitmap
1865 // and, if it's in a yield point, it's waiting for us to
1866 // finish. So, at this point we will not start a cycle and we'll
1867 // let the concurrent marking thread complete the last one.
1868 ergo_verbose0(ErgoConcCycles,
1869 "do not initiate concurrent cycle",
1870 ergo_format_reason("concurrent cycle already in progress"));
1871 }
1872 }
1873 }
1874
1875 class KnownGarbageClosure: public HeapRegionClosure {
1876 G1CollectedHeap* _g1h;
1877 CollectionSetChooser* _hrSorted;
1878
1879 public:
1880 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1881 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1882
1883 bool doHeapRegion(HeapRegion* r) {
1884 // We only include humongous regions in collection
1885 // sets when concurrent mark shows that their contained object is
1886 // unreachable.
1887
1888 // Do we have any marking information for this region?
1889 if (r->is_marked()) {
1890 // We will skip any region that's currently used as an old GC
1891 // alloc region (we should not consider those for collection
1892 // before we fill them up).
1893 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1894 _hrSorted->add_region(r);
1895 }
1896 }
1897 return false;
1898 }
1899 };
1900
1901 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1902 G1CollectedHeap* _g1h;
1903 CollectionSetChooser* _hrSorted;
1904 uint _marked_regions_added;
1905 size_t _reclaimable_bytes_added;
1906 uint _chunk_size;
1907 uint _cur_chunk_idx;
1908 uint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
1909
1910 void get_new_chunk() {
1911 _cur_chunk_idx = _hrSorted->claim_array_chunk(_chunk_size);
1912 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
1913 }
1914 void add_region(HeapRegion* r) {
1915 if (_cur_chunk_idx == _cur_chunk_end) {
1916 get_new_chunk();
1917 }
1918 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
1919 _hrSorted->set_region(_cur_chunk_idx, r);
1920 _marked_regions_added++;
1921 _reclaimable_bytes_added += r->reclaimable_bytes();
1922 _cur_chunk_idx++;
1923 }
1924
1925 public:
1926 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1927 uint chunk_size) :
1928 _g1h(G1CollectedHeap::heap()),
1929 _hrSorted(hrSorted), _chunk_size(chunk_size),
1930 _marked_regions_added(0), _reclaimable_bytes_added(0),
1931 _cur_chunk_idx(0), _cur_chunk_end(0) { }
1932
1933 bool doHeapRegion(HeapRegion* r) {
1934 // Do we have any marking information for this region?
1935 if (r->is_marked()) {
1936 // We will skip any region that's currently used as an old GC
1937 // alloc region (we should not consider those for collection
1938 // before we fill them up).
1939 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1940 add_region(r);
1941 }
1942 }
1943 return false;
1944 }
1945 uint marked_regions_added() { return _marked_regions_added; }
1946 size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
1947 };
1948
1949 class ParKnownGarbageTask: public AbstractGangTask {
1950 CollectionSetChooser* _hrSorted;
1951 uint _chunk_size;
1952 G1CollectedHeap* _g1;
1953 public:
1954 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1955 AbstractGangTask("ParKnownGarbageTask"),
1956 _hrSorted(hrSorted), _chunk_size(chunk_size),
1957 _g1(G1CollectedHeap::heap()) { }
1958
1959 void work(uint worker_id) {
1960 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1961
1962 // Back to zero for the claim value.
1963 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1964 _g1->workers()->active_workers(),
1965 HeapRegion::InitialClaimValue);
1966 uint regions_added = parKnownGarbageCl.marked_regions_added();
1967 size_t reclaimable_bytes_added =
1968 parKnownGarbageCl.reclaimable_bytes_added();
1969 _hrSorted->update_totals(regions_added, reclaimable_bytes_added);
1970 }
1971 };
1972
1973 void
1974 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1975 _collectionSetChooser->clear();
1976
1977 uint region_num = _g1->n_regions();
1978 if (G1CollectedHeap::use_parallel_gc_threads()) {
1979 const uint OverpartitionFactor = 4;
1980 uint WorkUnit;
1981 // The use of MinChunkSize = 8 in the original code
1982 // causes some assertion failures when the total number of
1983 // region is less than 8. The code here tries to fix that.
1984 // Should the original code also be fixed?
1985 if (no_of_gc_threads > 0) {
1986 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1987 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1988 MinWorkUnit);
1989 } else {
1990 assert(no_of_gc_threads > 0,
1991 "The active gc workers should be greater than 0");
1992 // In a product build do something reasonable to avoid a crash.
1993 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1994 WorkUnit =
1995 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1996 MinWorkUnit);
1997 }
1998 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1999 WorkUnit);
2000 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2001 (int) WorkUnit);
2002 _g1->workers()->run_task(&parKnownGarbageTask);
2003
2004 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2005 "sanity check");
2006 } else {
2007 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2008 _g1->heap_region_iterate(&knownGarbagecl);
2009 }
2010
2011 _collectionSetChooser->sort_regions();
2012
2013 double end_sec = os::elapsedTime();
2014 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
2015 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
2016 _cur_mark_stop_world_time_ms += elapsed_time_ms;
2017 _prev_collection_pause_end_ms += elapsed_time_ms;
2018 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
2019 }
2020
2021 // Add the heap region at the head of the non-incremental collection set
2022 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
2023 assert(_inc_cset_build_state == Active, "Precondition");
2024 assert(!hr->is_young(), "non-incremental add of young region");
2025
2026 assert(!hr->in_collection_set(), "should not already be in the CSet");
2027 hr->set_in_collection_set(true);
2028 hr->set_next_in_collection_set(_collection_set);
2029 _collection_set = hr;
2030 _collection_set_bytes_used_before += hr->used();
2031 _g1->register_region_with_in_cset_fast_test(hr);
2032 size_t rs_length = hr->rem_set()->occupied();
2033 _recorded_rs_lengths += rs_length;
2034 _old_cset_region_length += 1;
2035 }
2036
2037 // Initialize the per-collection-set information
2038 void G1CollectorPolicy::start_incremental_cset_building() {
2039 assert(_inc_cset_build_state == Inactive, "Precondition");
2040
2041 _inc_cset_head = NULL;
2042 _inc_cset_tail = NULL;
2043 _inc_cset_bytes_used_before = 0;
2044
2045 _inc_cset_max_finger = 0;
2046 _inc_cset_recorded_rs_lengths = 0;
2047 _inc_cset_recorded_rs_lengths_diffs = 0;
2048 _inc_cset_predicted_elapsed_time_ms = 0.0;
2049 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2050 _inc_cset_build_state = Active;
2051 }
2052
2053 void G1CollectorPolicy::finalize_incremental_cset_building() {
2054 assert(_inc_cset_build_state == Active, "Precondition");
2055 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2056
2057 // The two "main" fields, _inc_cset_recorded_rs_lengths and
2058 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
2059 // that adds a new region to the CSet. Further updates by the
2060 // concurrent refinement thread that samples the young RSet lengths
2061 // are accumulated in the *_diffs fields. Here we add the diffs to
2062 // the "main" fields.
2063
2064 if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
2065 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
2066 } else {
2067 // This is defensive. The diff should in theory be always positive
2068 // as RSets can only grow between GCs. However, given that we
2069 // sample their size concurrently with other threads updating them
2070 // it's possible that we might get the wrong size back, which
2071 // could make the calculations somewhat inaccurate.
2072 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
2073 if (_inc_cset_recorded_rs_lengths >= diffs) {
2074 _inc_cset_recorded_rs_lengths -= diffs;
2075 } else {
2076 _inc_cset_recorded_rs_lengths = 0;
2077 }
2078 }
2079 _inc_cset_predicted_elapsed_time_ms +=
2080 _inc_cset_predicted_elapsed_time_ms_diffs;
2081
2082 _inc_cset_recorded_rs_lengths_diffs = 0;
2083 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
2084 }
2085
2086 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2087 // This routine is used when:
2088 // * adding survivor regions to the incremental cset at the end of an
2089 // evacuation pause,
2090 // * adding the current allocation region to the incremental cset
2091 // when it is retired, and
2092 // * updating existing policy information for a region in the
2093 // incremental cset via young list RSet sampling.
2094 // Therefore this routine may be called at a safepoint by the
2095 // VM thread, or in-between safepoints by mutator threads (when
2096 // retiring the current allocation region) or a concurrent
2097 // refine thread (RSet sampling).
2098
2099 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2100 size_t used_bytes = hr->used();
2101 _inc_cset_recorded_rs_lengths += rs_length;
2102 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2103 _inc_cset_bytes_used_before += used_bytes;
2104
2105 // Cache the values we have added to the aggregated informtion
2106 // in the heap region in case we have to remove this region from
2107 // the incremental collection set, or it is updated by the
2108 // rset sampling code
2109 hr->set_recorded_rs_length(rs_length);
2110 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2111 }
2112
2113 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
2114 size_t new_rs_length) {
2115 // Update the CSet information that is dependent on the new RS length
2116 assert(hr->is_young(), "Precondition");
2117 assert(!SafepointSynchronize::is_at_safepoint(),
2118 "should not be at a safepoint");
2119
2120 // We could have updated _inc_cset_recorded_rs_lengths and
2121 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
2122 // that atomically, as this code is executed by a concurrent
2123 // refinement thread, potentially concurrently with a mutator thread
2124 // allocating a new region and also updating the same fields. To
2125 // avoid the atomic operations we accumulate these updates on two
2126 // separate fields (*_diffs) and we'll just add them to the "main"
2127 // fields at the start of a GC.
2128
2129 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
2130 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
2131 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
2132
2133 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2134 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2135 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
2136 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
2137
2138 hr->set_recorded_rs_length(new_rs_length);
2139 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
2140 }
2141
2142 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2143 assert(hr->is_young(), "invariant");
2144 assert(hr->young_index_in_cset() > -1, "should have already been set");
2145 assert(_inc_cset_build_state == Active, "Precondition");
2146
2147 // We need to clear and set the cached recorded/cached collection set
2148 // information in the heap region here (before the region gets added
2149 // to the collection set). An individual heap region's cached values
2150 // are calculated, aggregated with the policy collection set info,
2151 // and cached in the heap region here (initially) and (subsequently)
2152 // by the Young List sampling code.
2153
2154 size_t rs_length = hr->rem_set()->occupied();
2155 add_to_incremental_cset_info(hr, rs_length);
2156
2157 HeapWord* hr_end = hr->end();
2158 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2159
2160 assert(!hr->in_collection_set(), "invariant");
2161 hr->set_in_collection_set(true);
2162 assert( hr->next_in_collection_set() == NULL, "invariant");
2163
2164 _g1->register_region_with_in_cset_fast_test(hr);
2165 }
2166
2167 // Add the region at the RHS of the incremental cset
2168 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2169 // We should only ever be appending survivors at the end of a pause
2170 assert( hr->is_survivor(), "Logic");
2171
2172 // Do the 'common' stuff
2173 add_region_to_incremental_cset_common(hr);
2174
2175 // Now add the region at the right hand side
2176 if (_inc_cset_tail == NULL) {
2177 assert(_inc_cset_head == NULL, "invariant");
2178 _inc_cset_head = hr;
2179 } else {
2180 _inc_cset_tail->set_next_in_collection_set(hr);
2181 }
2182 _inc_cset_tail = hr;
2183 }
2184
2185 // Add the region to the LHS of the incremental cset
2186 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2187 // Survivors should be added to the RHS at the end of a pause
2188 assert(!hr->is_survivor(), "Logic");
2189
2190 // Do the 'common' stuff
2191 add_region_to_incremental_cset_common(hr);
2192
2193 // Add the region at the left hand side
2194 hr->set_next_in_collection_set(_inc_cset_head);
2195 if (_inc_cset_head == NULL) {
2196 assert(_inc_cset_tail == NULL, "Invariant");
2197 _inc_cset_tail = hr;
2198 }
2199 _inc_cset_head = hr;
2200 }
2201
2202 #ifndef PRODUCT
2203 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2204 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2205
2206 st->print_cr("\nCollection_set:");
2207 HeapRegion* csr = list_head;
2208 while (csr != NULL) {
2209 HeapRegion* next = csr->next_in_collection_set();
2210 assert(csr->in_collection_set(), "bad CS");
2211 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
2212 HR_FORMAT_PARAMS(csr),
2213 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
2214 csr->age_in_surv_rate_group_cond());
2215 csr = next;
2216 }
2217 }
2218 #endif // !PRODUCT
2219
2220 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2221 const char* false_action_str) {
2222 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2223 if (cset_chooser->is_empty()) {
2224 ergo_verbose0(ErgoMixedGCs,
2225 false_action_str,
2226 ergo_format_reason("candidate old regions not available"));
2227 return false;
2228 }
2229 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2230 size_t capacity_bytes = _g1->capacity();
2231 double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2232 double threshold = (double) G1HeapWastePercent;
2233 if (perc < threshold) {
2234 ergo_verbose4(ErgoMixedGCs,
2235 false_action_str,
2236 ergo_format_reason("reclaimable percentage lower than threshold")
2237 ergo_format_region("candidate old regions")
2238 ergo_format_byte_perc("reclaimable")
2239 ergo_format_perc("threshold"),
2240 cset_chooser->remaining_regions(),
2241 reclaimable_bytes, perc, threshold);
2242 return false;
2243 }
2244
2245 ergo_verbose4(ErgoMixedGCs,
2246 true_action_str,
2247 ergo_format_reason("candidate old regions available")
2248 ergo_format_region("candidate old regions")
2249 ergo_format_byte_perc("reclaimable")
2250 ergo_format_perc("threshold"),
2251 cset_chooser->remaining_regions(),
2252 reclaimable_bytes, perc, threshold);
2253 return true;
2254 }
2255
2256 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
2257 // Set this here - in case we're not doing young collections.
2258 double non_young_start_time_sec = os::elapsedTime();
2259
2260 YoungList* young_list = _g1->young_list();
2261 finalize_incremental_cset_building();
2262
2263 guarantee(target_pause_time_ms > 0.0,
2264 err_msg("target_pause_time_ms = %1.6lf should be positive",
2265 target_pause_time_ms));
2266 guarantee(_collection_set == NULL, "Precondition");
2267
2268 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2269 double predicted_pause_time_ms = base_time_ms;
2270 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2271
2272 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2273 "start choosing CSet",
2274 ergo_format_ms("predicted base time")
2275 ergo_format_ms("remaining time")
2276 ergo_format_ms("target pause time"),
2277 base_time_ms, time_remaining_ms, target_pause_time_ms);
2278
2279 HeapRegion* hr;
2280 double young_start_time_sec = os::elapsedTime();
2281
2282 _collection_set_bytes_used_before = 0;
2283 _last_gc_was_young = gcs_are_young() ? true : false;
2284
2285 if (_last_gc_was_young) {
2286 _trace_gen0_time_data.increment_young_collection_count();
2287 } else {
2288 _trace_gen0_time_data.increment_mixed_collection_count();
2289 }
2290
2291 // The young list is laid with the survivor regions from the previous
2292 // pause are appended to the RHS of the young list, i.e.
2293 // [Newly Young Regions ++ Survivors from last pause].
2294
2295 uint survivor_region_length = young_list->survivor_length();
2296 uint eden_region_length = young_list->length() - survivor_region_length;
2297 init_cset_region_lengths(eden_region_length, survivor_region_length);
2298 hr = young_list->first_survivor_region();
2299 while (hr != NULL) {
2300 assert(hr->is_survivor(), "badly formed young list");
2301 hr->set_young();
2302 hr = hr->get_next_young_region();
2303 }
2304
2305 // Clear the fields that point to the survivor list - they are all young now.
2306 young_list->clear_survivors();
2307
2308 _collection_set = _inc_cset_head;
2309 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2310 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2311 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2312
2313 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2314 "add young regions to CSet",
2315 ergo_format_region("eden")
2316 ergo_format_region("survivors")
2317 ergo_format_ms("predicted young region time"),
2318 eden_region_length, survivor_region_length,
2319 _inc_cset_predicted_elapsed_time_ms);
2320
2321 // The number of recorded young regions is the incremental
2322 // collection set's current size
2323 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2324
2325 double young_end_time_sec = os::elapsedTime();
2326 _recorded_young_cset_choice_time_ms =
2327 (young_end_time_sec - young_start_time_sec) * 1000.0;
2328
2329 // We are doing young collections so reset this.
2330 non_young_start_time_sec = young_end_time_sec;
2331
2332 if (!gcs_are_young()) {
2333 CollectionSetChooser* cset_chooser = _collectionSetChooser;
2334 cset_chooser->verify();
2335 const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
2336 const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
2337
2338 uint expensive_region_num = 0;
2339 bool check_time_remaining = adaptive_young_list_length();
2340 HeapRegion* hr = cset_chooser->peek();
2341 while (hr != NULL) {
2342 if (old_cset_region_length() >= max_old_cset_length) {
2343 // Added maximum number of old regions to the CSet.
2344 ergo_verbose2(ErgoCSetConstruction,
2345 "finish adding old regions to CSet",
2346 ergo_format_reason("old CSet region num reached max")
2347 ergo_format_region("old")
2348 ergo_format_region("max"),
2349 old_cset_region_length(), max_old_cset_length);
2350 break;
2351 }
2352
2353 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2354 if (check_time_remaining) {
2355 if (predicted_time_ms > time_remaining_ms) {
2356 // Too expensive for the current CSet.
2357
2358 if (old_cset_region_length() >= min_old_cset_length) {
2359 // We have added the minimum number of old regions to the CSet,
2360 // we are done with this CSet.
2361 ergo_verbose4(ErgoCSetConstruction,
2362 "finish adding old regions to CSet",
2363 ergo_format_reason("predicted time is too high")
2364 ergo_format_ms("predicted time")
2365 ergo_format_ms("remaining time")
2366 ergo_format_region("old")
2367 ergo_format_region("min"),
2368 predicted_time_ms, time_remaining_ms,
2369 old_cset_region_length(), min_old_cset_length);
2370 break;
2371 }
2372
2373 // We'll add it anyway given that we haven't reached the
2374 // minimum number of old regions.
2375 expensive_region_num += 1;
2376 }
2377 } else {
2378 if (old_cset_region_length() >= min_old_cset_length) {
2379 // In the non-auto-tuning case, we'll finish adding regions
2380 // to the CSet if we reach the minimum.
2381 ergo_verbose2(ErgoCSetConstruction,
2382 "finish adding old regions to CSet",
2383 ergo_format_reason("old CSet region num reached min")
2384 ergo_format_region("old")
2385 ergo_format_region("min"),
2386 old_cset_region_length(), min_old_cset_length);
2387 break;
2388 }
2389 }
2390
2391 // We will add this region to the CSet.
2392 time_remaining_ms -= predicted_time_ms;
2393 predicted_pause_time_ms += predicted_time_ms;
2394 cset_chooser->remove_and_move_to_next(hr);
2395 _g1->old_set_remove(hr);
2396 add_old_region_to_cset(hr);
2397
2398 hr = cset_chooser->peek();
2399 }
2400 if (hr == NULL) {
2401 ergo_verbose0(ErgoCSetConstruction,
2402 "finish adding old regions to CSet",
2403 ergo_format_reason("candidate old regions not available"));
2404 }
2405
2406 if (expensive_region_num > 0) {
2407 // We print the information once here at the end, predicated on
2408 // whether we added any apparently expensive regions or not, to
2409 // avoid generating output per region.
2410 ergo_verbose4(ErgoCSetConstruction,
2411 "added expensive regions to CSet",
2412 ergo_format_reason("old CSet region num not reached min")
2413 ergo_format_region("old")
2414 ergo_format_region("expensive")
2415 ergo_format_region("min")
2416 ergo_format_ms("remaining time"),
2417 old_cset_region_length(),
2418 expensive_region_num,
2419 min_old_cset_length,
2420 time_remaining_ms);
2421 }
2422
2423 cset_chooser->verify();
2424 }
2425
2426 stop_incremental_cset_building();
2427
2428 count_CS_bytes_used();
2429
2430 ergo_verbose5(ErgoCSetConstruction,
2431 "finish choosing CSet",
2432 ergo_format_region("eden")
2433 ergo_format_region("survivors")
2434 ergo_format_region("old")
2435 ergo_format_ms("predicted pause time")
2436 ergo_format_ms("target pause time"),
2437 eden_region_length, survivor_region_length,
2438 old_cset_region_length(),
2439 predicted_pause_time_ms, target_pause_time_ms);
2440
2441 double non_young_end_time_sec = os::elapsedTime();
2442 _recorded_non_young_cset_choice_time_ms =
2443 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2444 }
2445
2446 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2447 if(TraceGen0Time) {
2448 _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2449 }
2450 }
2451
2452 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2453 if(TraceGen0Time) {
2454 _all_yield_times_ms.add(yield_time_ms);
2455 }
2456 }
2457
2458 void TraceGen0TimeData::record_end_collection(
2459 double total_ms,
2460 double other_ms,
2461 double root_region_scan_wait_ms,
2462 double parallel_ms,
2463 double ext_root_scan_ms,
2464 double satb_filtering_ms,
2465 double update_rs_ms,
2466 double scan_rs_ms,
2467 double obj_copy_ms,
2468 double termination_ms,
2469 double parallel_other_ms,
2470 double clear_ct_ms)
2471 {
2472 if(TraceGen0Time) {
2473 _total.add(total_ms);
2474 _other.add(other_ms);
2475 _root_region_scan_wait.add(root_region_scan_wait_ms);
2476 _parallel.add(parallel_ms);
2477 _ext_root_scan.add(ext_root_scan_ms);
2478 _satb_filtering.add(satb_filtering_ms);
2479 _update_rs.add(update_rs_ms);
2480 _scan_rs.add(scan_rs_ms);
2481 _obj_copy.add(obj_copy_ms);
2482 _termination.add(termination_ms);
2483 _parallel_other.add(parallel_other_ms);
2484 _clear_ct.add(clear_ct_ms);
2485 }
2486 }
2487
2488 void TraceGen0TimeData::increment_young_collection_count() {
2489 if(TraceGen0Time) {
2490 ++_young_pause_num;
2491 }
2492 }
2493
2494 void TraceGen0TimeData::increment_mixed_collection_count() {
2495 if(TraceGen0Time) {
2496 ++_mixed_pause_num;
2497 }
2498 }
2499
2500 void TraceGen0TimeData::print_summary(int level,
2501 const char* str,
2502 const NumberSeq* seq) const {
2503 double sum = seq->sum();
2504 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
2505 str, sum / 1000.0, seq->avg());
2506 }
2507
2508 void TraceGen0TimeData::print_summary_sd(int level,
2509 const char* str,
2510 const NumberSeq* seq) const {
2511 print_summary(level, str, seq);
2512 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2513 seq->num(), seq->sd(), seq->maximum());
2514 }
2515
2516 void TraceGen0TimeData::print() const {
2517 if (!TraceGen0Time) {
2518 return;
2519 }
2520
2521 gclog_or_tty->print_cr("ALL PAUSES");
2522 print_summary_sd(0, "Total", &_total);
2523 gclog_or_tty->print_cr("");
2524 gclog_or_tty->print_cr("");
2525 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2526 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2527 gclog_or_tty->print_cr("");
2528
2529 gclog_or_tty->print_cr("EVACUATION PAUSES");
2530
2531 if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2532 gclog_or_tty->print_cr("none");
2533 } else {
2534 print_summary_sd(0, "Evacuation Pauses", &_total);
2535 print_summary(1, "Root Region Scan Wait", &_root_region_scan_wait);
2536 print_summary(1, "Parallel Time", &_parallel);
2537 print_summary(2, "Ext Root Scanning", &_ext_root_scan);
2538 print_summary(2, "SATB Filtering", &_satb_filtering);
2539 print_summary(2, "Update RS", &_update_rs);
2540 print_summary(2, "Scan RS", &_scan_rs);
2541 print_summary(2, "Object Copy", &_obj_copy);
2542 print_summary(2, "Termination", &_termination);
2543 print_summary(2, "Parallel Other", &_parallel_other);
2544 print_summary(1, "Clear CT", &_clear_ct);
2545 print_summary(1, "Other", &_other);
2546 }
2547 gclog_or_tty->print_cr("");
2548
2549 gclog_or_tty->print_cr("MISC");
2550 print_summary_sd(0, "Stop World", &_all_stop_world_times_ms);
2551 print_summary_sd(0, "Yields", &_all_yield_times_ms);
2552 }
2553
2554 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2555 if (TraceGen1Time) {
2556 _all_full_gc_times.add(full_gc_time_ms);
2557 }
2558 }
2559
2560 void TraceGen1TimeData::print() const {
2561 if (!TraceGen1Time) {
2562 return;
2563 }
2564
2565 if (_all_full_gc_times.num() > 0) {
2566 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2567 _all_full_gc_times.num(),
2568 _all_full_gc_times.sum() / 1000.0);
2569 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2570 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2571 _all_full_gc_times.sd(),
2572 _all_full_gc_times.maximum());
2573 }
2574 }