Fri, 16 Dec 2011 02:14:27 -0500
7113012: G1: rename not-fully-young GCs as "mixed"
Summary: Renamed partially-young GCs as mixed and fully-young GCs as young. Change all external output that includes those terms (GC log and GC ergo log) as well as any comments, fields, methods, etc. The changeset also includes very minor code tidying up (added some curly brackets).
Reviewed-by: johnc, brutisso
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentMark.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 #include "gc_implementation/shared/gcPolicyCounters.hpp"
34 #include "runtime/arguments.hpp"
35 #include "runtime/java.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "utilities/debug.hpp"
39 // Different defaults for different number of GC threads
40 // They were chosen by running GCOld and SPECjbb on debris with different
41 // numbers of GC threads and choosing them based on the results
43 // all the same
44 static double rs_length_diff_defaults[] = {
45 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
46 };
48 static double cost_per_card_ms_defaults[] = {
49 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
50 };
52 // all the same
53 static double young_cards_per_entry_ratio_defaults[] = {
54 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
55 };
57 static double cost_per_entry_ms_defaults[] = {
58 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
59 };
61 static double cost_per_byte_ms_defaults[] = {
62 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
63 };
65 // these should be pretty consistent
66 static double constant_other_time_ms_defaults[] = {
67 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
68 };
71 static double young_other_cost_per_region_ms_defaults[] = {
72 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
73 };
75 static double non_young_other_cost_per_region_ms_defaults[] = {
76 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
77 };
79 // Help class for avoiding interleaved logging
80 class LineBuffer: public StackObj {
82 private:
83 static const int BUFFER_LEN = 1024;
84 static const int INDENT_CHARS = 3;
85 char _buffer[BUFFER_LEN];
86 int _indent_level;
87 int _cur;
89 void vappend(const char* format, va_list ap) {
90 int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
91 if (res != -1) {
92 _cur += res;
93 } else {
94 DEBUG_ONLY(warning("buffer too small in LineBuffer");)
95 _buffer[BUFFER_LEN -1] = 0;
96 _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
97 }
98 }
100 public:
101 explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
102 for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
103 _buffer[_cur] = ' ';
104 }
105 }
107 #ifndef PRODUCT
108 ~LineBuffer() {
109 assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
110 }
111 #endif
113 void append(const char* format, ...) {
114 va_list ap;
115 va_start(ap, format);
116 vappend(format, ap);
117 va_end(ap);
118 }
120 void append_and_print_cr(const char* format, ...) {
121 va_list ap;
122 va_start(ap, format);
123 vappend(format, ap);
124 va_end(ap);
125 gclog_or_tty->print_cr("%s", _buffer);
126 _cur = _indent_level * INDENT_CHARS;
127 }
128 };
130 G1CollectorPolicy::G1CollectorPolicy() :
131 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
132 ? ParallelGCThreads : 1),
134 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
135 _all_pause_times_ms(new NumberSeq()),
136 _stop_world_start(0.0),
137 _all_stop_world_times_ms(new NumberSeq()),
138 _all_yield_times_ms(new NumberSeq()),
139 _using_new_ratio_calculations(false),
141 _summary(new Summary()),
143 _cur_clear_ct_time_ms(0.0),
144 _mark_closure_time_ms(0.0),
146 _cur_ref_proc_time_ms(0.0),
147 _cur_ref_enq_time_ms(0.0),
149 #ifndef PRODUCT
150 _min_clear_cc_time_ms(-1.0),
151 _max_clear_cc_time_ms(-1.0),
152 _cur_clear_cc_time_ms(0.0),
153 _cum_clear_cc_time_ms(0.0),
154 _num_cc_clears(0L),
155 #endif
157 _aux_num(10),
158 _all_aux_times_ms(new NumberSeq[_aux_num]),
159 _cur_aux_start_times_ms(new double[_aux_num]),
160 _cur_aux_times_ms(new double[_aux_num]),
161 _cur_aux_times_set(new bool[_aux_num]),
163 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
164 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
166 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
167 _prev_collection_pause_end_ms(0.0),
168 _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
169 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
170 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
171 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
172 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
173 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
174 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
175 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
176 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
177 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
178 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
179 _non_young_other_cost_per_region_ms_seq(
180 new TruncatedSeq(TruncatedSeqLength)),
182 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
183 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
185 _pause_time_target_ms((double) MaxGCPauseMillis),
187 _gcs_are_young(true),
188 _young_pause_num(0),
189 _mixed_pause_num(0),
191 _during_marking(false),
192 _in_marking_window(false),
193 _in_marking_window_im(false),
195 _known_garbage_ratio(0.0),
196 _known_garbage_bytes(0),
198 _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
200 _recent_prev_end_times_for_all_gcs_sec(
201 new TruncatedSeq(NumPrevPausesForHeuristics)),
203 _recent_avg_pause_time_ratio(0.0),
205 _all_full_gc_times_ms(new NumberSeq()),
207 _initiate_conc_mark_if_possible(false),
208 _during_initial_mark_pause(false),
209 _should_revert_to_young_gcs(false),
210 _last_young_gc(false),
211 _last_gc_was_young(false),
213 _eden_bytes_before_gc(0),
214 _survivor_bytes_before_gc(0),
215 _capacity_before_gc(0),
217 _prev_collection_pause_used_at_end_bytes(0),
219 _eden_cset_region_length(0),
220 _survivor_cset_region_length(0),
221 _old_cset_region_length(0),
223 _collection_set(NULL),
224 _collection_set_bytes_used_before(0),
226 // Incremental CSet attributes
227 _inc_cset_build_state(Inactive),
228 _inc_cset_head(NULL),
229 _inc_cset_tail(NULL),
230 _inc_cset_bytes_used_before(0),
231 _inc_cset_max_finger(NULL),
232 _inc_cset_recorded_rs_lengths(0),
233 _inc_cset_predicted_elapsed_time_ms(0.0),
235 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
236 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
237 #endif // _MSC_VER
239 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
240 G1YoungSurvRateNumRegionsSummary)),
241 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
242 G1YoungSurvRateNumRegionsSummary)),
243 // add here any more surv rate groups
244 _recorded_survivor_regions(0),
245 _recorded_survivor_head(NULL),
246 _recorded_survivor_tail(NULL),
247 _survivors_age_table(true),
249 _gc_overhead_perc(0.0) {
251 // Set up the region size and associated fields. Given that the
252 // policy is created before the heap, we have to set this up here,
253 // so it's done as soon as possible.
254 HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
255 HeapRegionRemSet::setup_remset_size();
257 G1ErgoVerbose::initialize();
258 if (PrintAdaptiveSizePolicy) {
259 // Currently, we only use a single switch for all the heuristics.
260 G1ErgoVerbose::set_enabled(true);
261 // Given that we don't currently have a verboseness level
262 // parameter, we'll hardcode this to high. This can be easily
263 // changed in the future.
264 G1ErgoVerbose::set_level(ErgoHigh);
265 } else {
266 G1ErgoVerbose::set_enabled(false);
267 }
269 // Verify PLAB sizes
270 const size_t region_size = HeapRegion::GrainWords;
271 if (YoungPLABSize > region_size || OldPLABSize > region_size) {
272 char buffer[128];
273 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
274 OldPLABSize > region_size ? "Old" : "Young", region_size);
275 vm_exit_during_initialization(buffer);
276 }
278 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
279 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
281 _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
282 _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
283 _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
285 _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
286 _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
288 _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
290 _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
292 _par_last_termination_times_ms = new double[_parallel_gc_threads];
293 _par_last_termination_attempts = new double[_parallel_gc_threads];
294 _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
295 _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
296 _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
298 // start conservatively
299 _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
301 int index;
302 if (ParallelGCThreads == 0)
303 index = 0;
304 else if (ParallelGCThreads > 8)
305 index = 7;
306 else
307 index = ParallelGCThreads - 1;
309 _pending_card_diff_seq->add(0.0);
310 _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
311 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
312 _young_cards_per_entry_ratio_seq->add(
313 young_cards_per_entry_ratio_defaults[index]);
314 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
315 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
316 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
317 _young_other_cost_per_region_ms_seq->add(
318 young_other_cost_per_region_ms_defaults[index]);
319 _non_young_other_cost_per_region_ms_seq->add(
320 non_young_other_cost_per_region_ms_defaults[index]);
322 // Below, we might need to calculate the pause time target based on
323 // the pause interval. When we do so we are going to give G1 maximum
324 // flexibility and allow it to do pauses when it needs to. So, we'll
325 // arrange that the pause interval to be pause time target + 1 to
326 // ensure that a) the pause time target is maximized with respect to
327 // the pause interval and b) we maintain the invariant that pause
328 // time target < pause interval. If the user does not want this
329 // maximum flexibility, they will have to set the pause interval
330 // explicitly.
332 // First make sure that, if either parameter is set, its value is
333 // reasonable.
334 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
335 if (MaxGCPauseMillis < 1) {
336 vm_exit_during_initialization("MaxGCPauseMillis should be "
337 "greater than 0");
338 }
339 }
340 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
341 if (GCPauseIntervalMillis < 1) {
342 vm_exit_during_initialization("GCPauseIntervalMillis should be "
343 "greater than 0");
344 }
345 }
347 // Then, if the pause time target parameter was not set, set it to
348 // the default value.
349 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
350 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
351 // The default pause time target in G1 is 200ms
352 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
353 } else {
354 // We do not allow the pause interval to be set without the
355 // pause time target
356 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
357 "without setting MaxGCPauseMillis");
358 }
359 }
361 // Then, if the interval parameter was not set, set it according to
362 // the pause time target (this will also deal with the case when the
363 // pause time target is the default value).
364 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
365 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
366 }
368 // Finally, make sure that the two parameters are consistent.
369 if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
370 char buffer[256];
371 jio_snprintf(buffer, 256,
372 "MaxGCPauseMillis (%u) should be less than "
373 "GCPauseIntervalMillis (%u)",
374 MaxGCPauseMillis, GCPauseIntervalMillis);
375 vm_exit_during_initialization(buffer);
376 }
378 double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
379 double time_slice = (double) GCPauseIntervalMillis / 1000.0;
380 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
381 _sigma = (double) G1ConfidencePercent / 100.0;
383 // start conservatively (around 50ms is about right)
384 _concurrent_mark_remark_times_ms->add(0.05);
385 _concurrent_mark_cleanup_times_ms->add(0.20);
386 _tenuring_threshold = MaxTenuringThreshold;
387 // _max_survivor_regions will be calculated by
388 // update_young_list_target_length() during initialization.
389 _max_survivor_regions = 0;
391 assert(GCTimeRatio > 0,
392 "we should have set it to a default value set_g1_gc_flags() "
393 "if a user set it to 0");
394 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
396 uintx reserve_perc = G1ReservePercent;
397 // Put an artificial ceiling on this so that it's not set to a silly value.
398 if (reserve_perc > 50) {
399 reserve_perc = 50;
400 warning("G1ReservePercent is set to a value that is too large, "
401 "it's been updated to %u", reserve_perc);
402 }
403 _reserve_factor = (double) reserve_perc / 100.0;
404 // This will be set when the heap is expanded
405 // for the first time during initialization.
406 _reserve_regions = 0;
408 initialize_all();
409 _collectionSetChooser = new CollectionSetChooser();
410 }
412 // Increment "i", mod "len"
413 static void inc_mod(int& i, int len) {
414 i++; if (i == len) i = 0;
415 }
417 void G1CollectorPolicy::initialize_flags() {
418 set_min_alignment(HeapRegion::GrainBytes);
419 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
420 if (SurvivorRatio < 1) {
421 vm_exit_during_initialization("Invalid survivor ratio specified");
422 }
423 CollectorPolicy::initialize_flags();
424 }
426 // The easiest way to deal with the parsing of the NewSize /
427 // MaxNewSize / etc. parameteres is to re-use the code in the
428 // TwoGenerationCollectorPolicy class. This is similar to what
429 // ParallelScavenge does with its GenerationSizer class (see
430 // ParallelScavengeHeap::initialize()). We might change this in the
431 // future, but it's a good start.
432 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
433 private:
434 size_t size_to_region_num(size_t byte_size) {
435 return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
436 }
438 public:
439 G1YoungGenSizer() {
440 initialize_flags();
441 initialize_size_info();
442 }
443 size_t min_young_region_num() {
444 return size_to_region_num(_min_gen0_size);
445 }
446 size_t initial_young_region_num() {
447 return size_to_region_num(_initial_gen0_size);
448 }
449 size_t max_young_region_num() {
450 return size_to_region_num(_max_gen0_size);
451 }
452 };
454 void G1CollectorPolicy::update_young_list_size_using_newratio(size_t number_of_heap_regions) {
455 assert(number_of_heap_regions > 0, "Heap must be initialized");
456 size_t young_size = number_of_heap_regions / (NewRatio + 1);
457 _min_desired_young_length = young_size;
458 _max_desired_young_length = young_size;
459 }
461 void G1CollectorPolicy::init() {
462 // Set aside an initial future to_space.
463 _g1 = G1CollectedHeap::heap();
465 assert(Heap_lock->owned_by_self(), "Locking discipline.");
467 initialize_gc_policy_counters();
469 G1YoungGenSizer sizer;
470 _min_desired_young_length = sizer.min_young_region_num();
471 _max_desired_young_length = sizer.max_young_region_num();
473 if (FLAG_IS_CMDLINE(NewRatio)) {
474 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
475 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
476 } else {
477 // Treat NewRatio as a fixed size that is only recalculated when the heap size changes
478 update_young_list_size_using_newratio(_g1->n_regions());
479 _using_new_ratio_calculations = true;
480 }
481 }
483 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
485 set_adaptive_young_list_length(_min_desired_young_length < _max_desired_young_length);
486 if (adaptive_young_list_length()) {
487 _young_list_fixed_length = 0;
488 } else {
489 assert(_min_desired_young_length == _max_desired_young_length, "Min and max young size differ");
490 _young_list_fixed_length = _min_desired_young_length;
491 }
492 _free_regions_at_end_of_collection = _g1->free_regions();
493 update_young_list_target_length();
494 _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
496 // We may immediately start allocating regions and placing them on the
497 // collection set list. Initialize the per-collection set info
498 start_incremental_cset_building();
499 }
501 // Create the jstat counters for the policy.
502 void G1CollectorPolicy::initialize_gc_policy_counters() {
503 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
504 }
506 bool G1CollectorPolicy::predict_will_fit(size_t young_length,
507 double base_time_ms,
508 size_t base_free_regions,
509 double target_pause_time_ms) {
510 if (young_length >= base_free_regions) {
511 // end condition 1: not enough space for the young regions
512 return false;
513 }
515 double accum_surv_rate = accum_yg_surv_rate_pred((int)(young_length - 1));
516 size_t bytes_to_copy =
517 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
518 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
519 double young_other_time_ms = predict_young_other_time_ms(young_length);
520 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
521 if (pause_time_ms > target_pause_time_ms) {
522 // end condition 2: prediction is over the target pause time
523 return false;
524 }
526 size_t free_bytes =
527 (base_free_regions - young_length) * HeapRegion::GrainBytes;
528 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
529 // end condition 3: out-of-space (conservatively!)
530 return false;
531 }
533 // success!
534 return true;
535 }
537 void G1CollectorPolicy::record_new_heap_size(size_t new_number_of_regions) {
538 // re-calculate the necessary reserve
539 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
540 // We use ceiling so that if reserve_regions_d is > 0.0 (but
541 // smaller than 1.0) we'll get 1.
542 _reserve_regions = (size_t) ceil(reserve_regions_d);
544 if (_using_new_ratio_calculations) {
545 // -XX:NewRatio was specified so we need to update the
546 // young gen length when the heap size has changed.
547 update_young_list_size_using_newratio(new_number_of_regions);
548 }
549 }
551 size_t G1CollectorPolicy::calculate_young_list_desired_min_length(
552 size_t base_min_length) {
553 size_t desired_min_length = 0;
554 if (adaptive_young_list_length()) {
555 if (_alloc_rate_ms_seq->num() > 3) {
556 double now_sec = os::elapsedTime();
557 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
558 double alloc_rate_ms = predict_alloc_rate_ms();
559 desired_min_length = (size_t) ceil(alloc_rate_ms * when_ms);
560 } else {
561 // otherwise we don't have enough info to make the prediction
562 }
563 }
564 desired_min_length += base_min_length;
565 // make sure we don't go below any user-defined minimum bound
566 return MAX2(_min_desired_young_length, desired_min_length);
567 }
569 size_t G1CollectorPolicy::calculate_young_list_desired_max_length() {
570 // Here, we might want to also take into account any additional
571 // constraints (i.e., user-defined minimum bound). Currently, we
572 // effectively don't set this bound.
573 return _max_desired_young_length;
574 }
576 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
577 if (rs_lengths == (size_t) -1) {
578 // if it's set to the default value (-1), we should predict it;
579 // otherwise, use the given value.
580 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
581 }
583 // Calculate the absolute and desired min bounds.
585 // This is how many young regions we already have (currently: the survivors).
586 size_t base_min_length = recorded_survivor_regions();
587 // This is the absolute minimum young length, which ensures that we
588 // can allocate one eden region in the worst-case.
589 size_t absolute_min_length = base_min_length + 1;
590 size_t desired_min_length =
591 calculate_young_list_desired_min_length(base_min_length);
592 if (desired_min_length < absolute_min_length) {
593 desired_min_length = absolute_min_length;
594 }
596 // Calculate the absolute and desired max bounds.
598 // We will try our best not to "eat" into the reserve.
599 size_t absolute_max_length = 0;
600 if (_free_regions_at_end_of_collection > _reserve_regions) {
601 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
602 }
603 size_t desired_max_length = calculate_young_list_desired_max_length();
604 if (desired_max_length > absolute_max_length) {
605 desired_max_length = absolute_max_length;
606 }
608 size_t young_list_target_length = 0;
609 if (adaptive_young_list_length()) {
610 if (gcs_are_young()) {
611 young_list_target_length =
612 calculate_young_list_target_length(rs_lengths,
613 base_min_length,
614 desired_min_length,
615 desired_max_length);
616 _rs_lengths_prediction = rs_lengths;
617 } else {
618 // Don't calculate anything and let the code below bound it to
619 // the desired_min_length, i.e., do the next GC as soon as
620 // possible to maximize how many old regions we can add to it.
621 }
622 } else {
623 if (gcs_are_young()) {
624 young_list_target_length = _young_list_fixed_length;
625 } else {
626 // A bit arbitrary: during mixed GCs we allocate half
627 // the young regions to try to add old regions to the CSet.
628 young_list_target_length = _young_list_fixed_length / 2;
629 // We choose to accept that we might go under the desired min
630 // length given that we intentionally ask for a smaller young gen.
631 desired_min_length = absolute_min_length;
632 }
633 }
635 // Make sure we don't go over the desired max length, nor under the
636 // desired min length. In case they clash, desired_min_length wins
637 // which is why that test is second.
638 if (young_list_target_length > desired_max_length) {
639 young_list_target_length = desired_max_length;
640 }
641 if (young_list_target_length < desired_min_length) {
642 young_list_target_length = desired_min_length;
643 }
645 assert(young_list_target_length > recorded_survivor_regions(),
646 "we should be able to allocate at least one eden region");
647 assert(young_list_target_length >= absolute_min_length, "post-condition");
648 _young_list_target_length = young_list_target_length;
650 update_max_gc_locker_expansion();
651 }
653 size_t
654 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
655 size_t base_min_length,
656 size_t desired_min_length,
657 size_t desired_max_length) {
658 assert(adaptive_young_list_length(), "pre-condition");
659 assert(gcs_are_young(), "only call this for young GCs");
661 // In case some edge-condition makes the desired max length too small...
662 if (desired_max_length <= desired_min_length) {
663 return desired_min_length;
664 }
666 // We'll adjust min_young_length and max_young_length not to include
667 // the already allocated young regions (i.e., so they reflect the
668 // min and max eden regions we'll allocate). The base_min_length
669 // will be reflected in the predictions by the
670 // survivor_regions_evac_time prediction.
671 assert(desired_min_length > base_min_length, "invariant");
672 size_t min_young_length = desired_min_length - base_min_length;
673 assert(desired_max_length > base_min_length, "invariant");
674 size_t max_young_length = desired_max_length - base_min_length;
676 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
677 double survivor_regions_evac_time = predict_survivor_regions_evac_time();
678 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
679 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
680 size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
681 double base_time_ms =
682 predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
683 survivor_regions_evac_time;
684 size_t available_free_regions = _free_regions_at_end_of_collection;
685 size_t base_free_regions = 0;
686 if (available_free_regions > _reserve_regions) {
687 base_free_regions = available_free_regions - _reserve_regions;
688 }
690 // Here, we will make sure that the shortest young length that
691 // makes sense fits within the target pause time.
693 if (predict_will_fit(min_young_length, base_time_ms,
694 base_free_regions, target_pause_time_ms)) {
695 // The shortest young length will fit into the target pause time;
696 // we'll now check whether the absolute maximum number of young
697 // regions will fit in the target pause time. If not, we'll do
698 // a binary search between min_young_length and max_young_length.
699 if (predict_will_fit(max_young_length, base_time_ms,
700 base_free_regions, target_pause_time_ms)) {
701 // The maximum young length will fit into the target pause time.
702 // We are done so set min young length to the maximum length (as
703 // the result is assumed to be returned in min_young_length).
704 min_young_length = max_young_length;
705 } else {
706 // The maximum possible number of young regions will not fit within
707 // the target pause time so we'll search for the optimal
708 // length. The loop invariants are:
709 //
710 // min_young_length < max_young_length
711 // min_young_length is known to fit into the target pause time
712 // max_young_length is known not to fit into the target pause time
713 //
714 // Going into the loop we know the above hold as we've just
715 // checked them. Every time around the loop we check whether
716 // the middle value between min_young_length and
717 // max_young_length fits into the target pause time. If it
718 // does, it becomes the new min. If it doesn't, it becomes
719 // the new max. This way we maintain the loop invariants.
721 assert(min_young_length < max_young_length, "invariant");
722 size_t diff = (max_young_length - min_young_length) / 2;
723 while (diff > 0) {
724 size_t young_length = min_young_length + diff;
725 if (predict_will_fit(young_length, base_time_ms,
726 base_free_regions, target_pause_time_ms)) {
727 min_young_length = young_length;
728 } else {
729 max_young_length = young_length;
730 }
731 assert(min_young_length < max_young_length, "invariant");
732 diff = (max_young_length - min_young_length) / 2;
733 }
734 // The results is min_young_length which, according to the
735 // loop invariants, should fit within the target pause time.
737 // These are the post-conditions of the binary search above:
738 assert(min_young_length < max_young_length,
739 "otherwise we should have discovered that max_young_length "
740 "fits into the pause target and not done the binary search");
741 assert(predict_will_fit(min_young_length, base_time_ms,
742 base_free_regions, target_pause_time_ms),
743 "min_young_length, the result of the binary search, should "
744 "fit into the pause target");
745 assert(!predict_will_fit(min_young_length + 1, base_time_ms,
746 base_free_regions, target_pause_time_ms),
747 "min_young_length, the result of the binary search, should be "
748 "optimal, so no larger length should fit into the pause target");
749 }
750 } else {
751 // Even the minimum length doesn't fit into the pause time
752 // target, return it as the result nevertheless.
753 }
754 return base_min_length + min_young_length;
755 }
757 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
758 double survivor_regions_evac_time = 0.0;
759 for (HeapRegion * r = _recorded_survivor_head;
760 r != NULL && r != _recorded_survivor_tail->get_next_young_region();
761 r = r->get_next_young_region()) {
762 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
763 }
764 return survivor_regions_evac_time;
765 }
767 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
768 guarantee( adaptive_young_list_length(), "should not call this otherwise" );
770 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
771 if (rs_lengths > _rs_lengths_prediction) {
772 // add 10% to avoid having to recalculate often
773 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
774 update_young_list_target_length(rs_lengths_prediction);
775 }
776 }
780 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
781 bool is_tlab,
782 bool* gc_overhead_limit_was_exceeded) {
783 guarantee(false, "Not using this policy feature yet.");
784 return NULL;
785 }
787 // This method controls how a collector handles one or more
788 // of its generations being fully allocated.
789 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
790 bool is_tlab) {
791 guarantee(false, "Not using this policy feature yet.");
792 return NULL;
793 }
796 #ifndef PRODUCT
797 bool G1CollectorPolicy::verify_young_ages() {
798 HeapRegion* head = _g1->young_list()->first_region();
799 return
800 verify_young_ages(head, _short_lived_surv_rate_group);
801 // also call verify_young_ages on any additional surv rate groups
802 }
804 bool
805 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
806 SurvRateGroup *surv_rate_group) {
807 guarantee( surv_rate_group != NULL, "pre-condition" );
809 const char* name = surv_rate_group->name();
810 bool ret = true;
811 int prev_age = -1;
813 for (HeapRegion* curr = head;
814 curr != NULL;
815 curr = curr->get_next_young_region()) {
816 SurvRateGroup* group = curr->surv_rate_group();
817 if (group == NULL && !curr->is_survivor()) {
818 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
819 ret = false;
820 }
822 if (surv_rate_group == group) {
823 int age = curr->age_in_surv_rate_group();
825 if (age < 0) {
826 gclog_or_tty->print_cr("## %s: encountered negative age", name);
827 ret = false;
828 }
830 if (age <= prev_age) {
831 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
832 "(%d, %d)", name, age, prev_age);
833 ret = false;
834 }
835 prev_age = age;
836 }
837 }
839 return ret;
840 }
841 #endif // PRODUCT
843 void G1CollectorPolicy::record_full_collection_start() {
844 _cur_collection_start_sec = os::elapsedTime();
845 // Release the future to-space so that it is available for compaction into.
846 _g1->set_full_collection();
847 }
849 void G1CollectorPolicy::record_full_collection_end() {
850 // Consider this like a collection pause for the purposes of allocation
851 // since last pause.
852 double end_sec = os::elapsedTime();
853 double full_gc_time_sec = end_sec - _cur_collection_start_sec;
854 double full_gc_time_ms = full_gc_time_sec * 1000.0;
856 _all_full_gc_times_ms->add(full_gc_time_ms);
858 update_recent_gc_times(end_sec, full_gc_time_ms);
860 _g1->clear_full_collection();
862 // "Nuke" the heuristics that control the young/mixed GC
863 // transitions and make sure we start with young GCs after the Full GC.
864 set_gcs_are_young(true);
865 _last_young_gc = false;
866 _should_revert_to_young_gcs = false;
867 clear_initiate_conc_mark_if_possible();
868 clear_during_initial_mark_pause();
869 _known_garbage_bytes = 0;
870 _known_garbage_ratio = 0.0;
871 _in_marking_window = false;
872 _in_marking_window_im = false;
874 _short_lived_surv_rate_group->start_adding_regions();
875 // also call this on any additional surv rate groups
877 record_survivor_regions(0, NULL, NULL);
879 _free_regions_at_end_of_collection = _g1->free_regions();
880 // Reset survivors SurvRateGroup.
881 _survivor_surv_rate_group->reset();
882 update_young_list_target_length();
883 _collectionSetChooser->updateAfterFullCollection();
884 }
886 void G1CollectorPolicy::record_stop_world_start() {
887 _stop_world_start = os::elapsedTime();
888 }
890 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
891 size_t start_used) {
892 if (PrintGCDetails) {
893 gclog_or_tty->stamp(PrintGCTimeStamps);
894 gclog_or_tty->print("[GC pause");
895 gclog_or_tty->print(" (%s)", gcs_are_young() ? "young" : "mixed");
896 }
898 // We only need to do this here as the policy will only be applied
899 // to the GC we're about to start. so, no point is calculating this
900 // every time we calculate / recalculate the target young length.
901 update_survivors_policy();
903 assert(_g1->used() == _g1->recalculate_used(),
904 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
905 _g1->used(), _g1->recalculate_used()));
907 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
908 _all_stop_world_times_ms->add(s_w_t_ms);
909 _stop_world_start = 0.0;
911 _cur_collection_start_sec = start_time_sec;
912 _cur_collection_pause_used_at_start_bytes = start_used;
913 _cur_collection_pause_used_regions_at_start = _g1->used_regions();
914 _pending_cards = _g1->pending_card_num();
915 _max_pending_cards = _g1->max_pending_card_num();
917 _bytes_in_collection_set_before_gc = 0;
918 _bytes_copied_during_gc = 0;
920 YoungList* young_list = _g1->young_list();
921 _eden_bytes_before_gc = young_list->eden_used_bytes();
922 _survivor_bytes_before_gc = young_list->survivor_used_bytes();
923 _capacity_before_gc = _g1->capacity();
925 #ifdef DEBUG
926 // initialise these to something well known so that we can spot
927 // if they are not set properly
929 for (int i = 0; i < _parallel_gc_threads; ++i) {
930 _par_last_gc_worker_start_times_ms[i] = -1234.0;
931 _par_last_ext_root_scan_times_ms[i] = -1234.0;
932 _par_last_mark_stack_scan_times_ms[i] = -1234.0;
933 _par_last_update_rs_times_ms[i] = -1234.0;
934 _par_last_update_rs_processed_buffers[i] = -1234.0;
935 _par_last_scan_rs_times_ms[i] = -1234.0;
936 _par_last_obj_copy_times_ms[i] = -1234.0;
937 _par_last_termination_times_ms[i] = -1234.0;
938 _par_last_termination_attempts[i] = -1234.0;
939 _par_last_gc_worker_end_times_ms[i] = -1234.0;
940 _par_last_gc_worker_times_ms[i] = -1234.0;
941 _par_last_gc_worker_other_times_ms[i] = -1234.0;
942 }
943 #endif
945 for (int i = 0; i < _aux_num; ++i) {
946 _cur_aux_times_ms[i] = 0.0;
947 _cur_aux_times_set[i] = false;
948 }
950 // This is initialized to zero here and is set during
951 // the evacuation pause if marking is in progress.
952 _cur_satb_drain_time_ms = 0.0;
954 _last_gc_was_young = false;
956 // do that for any other surv rate groups
957 _short_lived_surv_rate_group->stop_adding_regions();
958 _survivors_age_table.clear();
960 assert( verify_young_ages(), "region age verification" );
961 }
963 void G1CollectorPolicy::record_concurrent_mark_init_end(double
964 mark_init_elapsed_time_ms) {
965 _during_marking = true;
966 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
967 clear_during_initial_mark_pause();
968 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
969 }
971 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
972 _mark_remark_start_sec = os::elapsedTime();
973 _during_marking = false;
974 }
976 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
977 double end_time_sec = os::elapsedTime();
978 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
979 _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
980 _cur_mark_stop_world_time_ms += elapsed_time_ms;
981 _prev_collection_pause_end_ms += elapsed_time_ms;
983 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
984 }
986 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
987 _mark_cleanup_start_sec = os::elapsedTime();
988 }
990 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
991 _should_revert_to_young_gcs = false;
992 _last_young_gc = true;
993 _in_marking_window = false;
994 }
996 void G1CollectorPolicy::record_concurrent_pause() {
997 if (_stop_world_start > 0.0) {
998 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
999 _all_yield_times_ms->add(yield_ms);
1000 }
1001 }
1003 void G1CollectorPolicy::record_concurrent_pause_end() {
1004 }
1006 template<class T>
1007 T sum_of(T* sum_arr, int start, int n, int N) {
1008 T sum = (T)0;
1009 for (int i = 0; i < n; i++) {
1010 int j = (start + i) % N;
1011 sum += sum_arr[j];
1012 }
1013 return sum;
1014 }
1016 void G1CollectorPolicy::print_par_stats(int level,
1017 const char* str,
1018 double* data) {
1019 double min = data[0], max = data[0];
1020 double total = 0.0;
1021 LineBuffer buf(level);
1022 buf.append("[%s (ms):", str);
1023 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1024 double val = data[i];
1025 if (val < min)
1026 min = val;
1027 if (val > max)
1028 max = val;
1029 total += val;
1030 buf.append(" %3.1lf", val);
1031 }
1032 buf.append_and_print_cr("");
1033 double avg = total / (double) no_of_gc_threads();
1034 buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
1035 avg, min, max, max - min);
1036 }
1038 void G1CollectorPolicy::print_par_sizes(int level,
1039 const char* str,
1040 double* data) {
1041 double min = data[0], max = data[0];
1042 double total = 0.0;
1043 LineBuffer buf(level);
1044 buf.append("[%s :", str);
1045 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1046 double val = data[i];
1047 if (val < min)
1048 min = val;
1049 if (val > max)
1050 max = val;
1051 total += val;
1052 buf.append(" %d", (int) val);
1053 }
1054 buf.append_and_print_cr("");
1055 double avg = total / (double) no_of_gc_threads();
1056 buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
1057 (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
1058 }
1060 void G1CollectorPolicy::print_stats(int level,
1061 const char* str,
1062 double value) {
1063 LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
1064 }
1066 void G1CollectorPolicy::print_stats(int level,
1067 const char* str,
1068 int value) {
1069 LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
1070 }
1072 double G1CollectorPolicy::avg_value(double* data) {
1073 if (G1CollectedHeap::use_parallel_gc_threads()) {
1074 double ret = 0.0;
1075 for (uint i = 0; i < no_of_gc_threads(); ++i) {
1076 ret += data[i];
1077 }
1078 return ret / (double) no_of_gc_threads();
1079 } else {
1080 return data[0];
1081 }
1082 }
1084 double G1CollectorPolicy::max_value(double* data) {
1085 if (G1CollectedHeap::use_parallel_gc_threads()) {
1086 double ret = data[0];
1087 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1088 if (data[i] > ret) {
1089 ret = data[i];
1090 }
1091 }
1092 return ret;
1093 } else {
1094 return data[0];
1095 }
1096 }
1098 double G1CollectorPolicy::sum_of_values(double* data) {
1099 if (G1CollectedHeap::use_parallel_gc_threads()) {
1100 double sum = 0.0;
1101 for (uint i = 0; i < no_of_gc_threads(); i++) {
1102 sum += data[i];
1103 }
1104 return sum;
1105 } else {
1106 return data[0];
1107 }
1108 }
1110 double G1CollectorPolicy::max_sum(double* data1, double* data2) {
1111 double ret = data1[0] + data2[0];
1113 if (G1CollectedHeap::use_parallel_gc_threads()) {
1114 for (uint i = 1; i < no_of_gc_threads(); ++i) {
1115 double data = data1[i] + data2[i];
1116 if (data > ret) {
1117 ret = data;
1118 }
1119 }
1120 }
1121 return ret;
1122 }
1124 // Anything below that is considered to be zero
1125 #define MIN_TIMER_GRANULARITY 0.0000001
1127 void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
1128 double end_time_sec = os::elapsedTime();
1129 double elapsed_ms = _last_pause_time_ms;
1130 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1131 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1132 "otherwise, the subtraction below does not make sense");
1133 size_t rs_size =
1134 _cur_collection_pause_used_regions_at_start - cset_region_length();
1135 size_t cur_used_bytes = _g1->used();
1136 assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1137 bool last_pause_included_initial_mark = false;
1138 bool update_stats = !_g1->evacuation_failed();
1139 set_no_of_gc_threads(no_of_gc_threads);
1141 #ifndef PRODUCT
1142 if (G1YoungSurvRateVerbose) {
1143 gclog_or_tty->print_cr("");
1144 _short_lived_surv_rate_group->print();
1145 // do that for any other surv rate groups too
1146 }
1147 #endif // PRODUCT
1149 last_pause_included_initial_mark = during_initial_mark_pause();
1150 if (last_pause_included_initial_mark)
1151 record_concurrent_mark_init_end(0.0);
1153 size_t marking_initiating_used_threshold =
1154 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
1156 if (!_g1->mark_in_progress() && !_last_young_gc) {
1157 assert(!last_pause_included_initial_mark, "invariant");
1158 if (cur_used_bytes > marking_initiating_used_threshold) {
1159 if (cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
1160 assert(!during_initial_mark_pause(), "we should not see this here");
1162 ergo_verbose3(ErgoConcCycles,
1163 "request concurrent cycle initiation",
1164 ergo_format_reason("occupancy higher than threshold")
1165 ergo_format_byte("occupancy")
1166 ergo_format_byte_perc("threshold"),
1167 cur_used_bytes,
1168 marking_initiating_used_threshold,
1169 (double) InitiatingHeapOccupancyPercent);
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 } else {
1176 ergo_verbose2(ErgoConcCycles,
1177 "do not request concurrent cycle initiation",
1178 ergo_format_reason("occupancy lower than previous occupancy")
1179 ergo_format_byte("occupancy")
1180 ergo_format_byte("previous occupancy"),
1181 cur_used_bytes,
1182 _prev_collection_pause_used_at_end_bytes);
1183 }
1184 }
1185 }
1187 _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
1189 _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
1190 end_time_sec, false);
1192 // This assert is exempted when we're doing parallel collection pauses,
1193 // because the fragmentation caused by the parallel GC allocation buffers
1194 // can lead to more memory being used during collection than was used
1195 // before. Best leave this out until the fragmentation problem is fixed.
1196 // Pauses in which evacuation failed can also lead to negative
1197 // collections, since no space is reclaimed from a region containing an
1198 // object whose evacuation failed.
1199 // Further, we're now always doing parallel collection. But I'm still
1200 // leaving this here as a placeholder for a more precise assertion later.
1201 // (DLD, 10/05.)
1202 assert((true || parallel) // Always using GC LABs now.
1203 || _g1->evacuation_failed()
1204 || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
1205 "Negative collection");
1207 size_t freed_bytes =
1208 _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
1209 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
1211 double survival_fraction =
1212 (double)surviving_bytes/
1213 (double)_collection_set_bytes_used_before;
1215 // These values are used to update the summary information that is
1216 // displayed when TraceGen0Time is enabled, and are output as part
1217 // of the PrintGCDetails output, in the non-parallel case.
1219 double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
1220 double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
1221 double update_rs_time = avg_value(_par_last_update_rs_times_ms);
1222 double update_rs_processed_buffers =
1223 sum_of_values(_par_last_update_rs_processed_buffers);
1224 double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
1225 double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
1226 double termination_time = avg_value(_par_last_termination_times_ms);
1228 double known_time = ext_root_scan_time +
1229 mark_stack_scan_time +
1230 update_rs_time +
1231 scan_rs_time +
1232 obj_copy_time;
1234 double other_time_ms = elapsed_ms;
1236 // Subtract the SATB drain time. It's initialized to zero at the
1237 // start of the pause and is updated during the pause if marking
1238 // is in progress.
1239 other_time_ms -= _cur_satb_drain_time_ms;
1241 if (parallel) {
1242 other_time_ms -= _cur_collection_par_time_ms;
1243 } else {
1244 other_time_ms -= known_time;
1245 }
1247 // Subtract the time taken to clean the card table from the
1248 // current value of "other time"
1249 other_time_ms -= _cur_clear_ct_time_ms;
1251 // Subtract the time spent completing marking in the collection
1252 // set. Note if marking is not in progress during the pause
1253 // the value of _mark_closure_time_ms will be zero.
1254 other_time_ms -= _mark_closure_time_ms;
1256 // TraceGen0Time and TraceGen1Time summary info updating.
1257 _all_pause_times_ms->add(elapsed_ms);
1259 if (update_stats) {
1260 _summary->record_total_time_ms(elapsed_ms);
1261 _summary->record_other_time_ms(other_time_ms);
1263 MainBodySummary* body_summary = _summary->main_body_summary();
1264 assert(body_summary != NULL, "should not be null!");
1266 // This will be non-zero iff marking is currently in progress (i.e.
1267 // _g1->mark_in_progress() == true) and the currrent pause was not
1268 // an initial mark pause. Since the body_summary items are NumberSeqs,
1269 // however, they have to be consistent and updated in lock-step with
1270 // each other. Therefore we unconditionally record the SATB drain
1271 // time - even if it's zero.
1272 body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
1274 body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
1275 body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
1276 body_summary->record_update_rs_time_ms(update_rs_time);
1277 body_summary->record_scan_rs_time_ms(scan_rs_time);
1278 body_summary->record_obj_copy_time_ms(obj_copy_time);
1280 if (parallel) {
1281 body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
1282 body_summary->record_termination_time_ms(termination_time);
1284 double parallel_known_time = known_time + termination_time;
1285 double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
1286 body_summary->record_parallel_other_time_ms(parallel_other_time);
1287 }
1289 body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
1290 body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
1292 // We exempt parallel collection from this check because Alloc Buffer
1293 // fragmentation can produce negative collections. Same with evac
1294 // failure.
1295 // Further, we're now always doing parallel collection. But I'm still
1296 // leaving this here as a placeholder for a more precise assertion later.
1297 // (DLD, 10/05.
1298 assert((true || parallel)
1299 || _g1->evacuation_failed()
1300 || surviving_bytes <= _collection_set_bytes_used_before,
1301 "Or else negative collection!");
1303 // this is where we update the allocation rate of the application
1304 double app_time_ms =
1305 (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
1306 if (app_time_ms < MIN_TIMER_GRANULARITY) {
1307 // This usually happens due to the timer not having the required
1308 // granularity. Some Linuxes are the usual culprits.
1309 // We'll just set it to something (arbitrarily) small.
1310 app_time_ms = 1.0;
1311 }
1312 // We maintain the invariant that all objects allocated by mutator
1313 // threads will be allocated out of eden regions. So, we can use
1314 // the eden region number allocated since the previous GC to
1315 // calculate the application's allocate rate. The only exception
1316 // to that is humongous objects that are allocated separately. But
1317 // given that humongous object allocations do not really affect
1318 // either the pause's duration nor when the next pause will take
1319 // place we can safely ignore them here.
1320 size_t regions_allocated = eden_cset_region_length();
1321 double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1322 _alloc_rate_ms_seq->add(alloc_rate_ms);
1324 double interval_ms =
1325 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1326 update_recent_gc_times(end_time_sec, elapsed_ms);
1327 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1328 if (recent_avg_pause_time_ratio() < 0.0 ||
1329 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1330 #ifndef PRODUCT
1331 // Dump info to allow post-facto debugging
1332 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1333 gclog_or_tty->print_cr("-------------------------------------------");
1334 gclog_or_tty->print_cr("Recent GC Times (ms):");
1335 _recent_gc_times_ms->dump();
1336 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1337 _recent_prev_end_times_for_all_gcs_sec->dump();
1338 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1339 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1340 // In debug mode, terminate the JVM if the user wants to debug at this point.
1341 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1342 #endif // !PRODUCT
1343 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1344 // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1345 if (_recent_avg_pause_time_ratio < 0.0) {
1346 _recent_avg_pause_time_ratio = 0.0;
1347 } else {
1348 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1349 _recent_avg_pause_time_ratio = 1.0;
1350 }
1351 }
1352 }
1354 for (int i = 0; i < _aux_num; ++i) {
1355 if (_cur_aux_times_set[i]) {
1356 _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
1357 }
1358 }
1360 // PrintGCDetails output
1361 if (PrintGCDetails) {
1362 bool print_marking_info =
1363 _g1->mark_in_progress() && !last_pause_included_initial_mark;
1365 gclog_or_tty->print_cr("%s, %1.8lf secs]",
1366 (last_pause_included_initial_mark) ? " (initial-mark)" : "",
1367 elapsed_ms / 1000.0);
1369 if (print_marking_info) {
1370 print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
1371 }
1373 if (parallel) {
1374 print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
1375 print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
1376 print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
1377 if (print_marking_info) {
1378 print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
1379 }
1380 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
1381 print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
1382 print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
1383 print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
1384 print_par_stats(2, "Termination", _par_last_termination_times_ms);
1385 print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
1386 print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
1388 for (int i = 0; i < _parallel_gc_threads; i++) {
1389 _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
1391 double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
1392 _par_last_mark_stack_scan_times_ms[i] +
1393 _par_last_update_rs_times_ms[i] +
1394 _par_last_scan_rs_times_ms[i] +
1395 _par_last_obj_copy_times_ms[i] +
1396 _par_last_termination_times_ms[i];
1398 _par_last_gc_worker_other_times_ms[i] = _cur_collection_par_time_ms - worker_known_time;
1399 }
1400 print_par_stats(2, "GC Worker", _par_last_gc_worker_times_ms);
1401 print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
1402 } else {
1403 print_stats(1, "Ext Root Scanning", ext_root_scan_time);
1404 if (print_marking_info) {
1405 print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
1406 }
1407 print_stats(1, "Update RS", update_rs_time);
1408 print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
1409 print_stats(1, "Scan RS", scan_rs_time);
1410 print_stats(1, "Object Copying", obj_copy_time);
1411 }
1412 if (print_marking_info) {
1413 print_stats(1, "Complete CSet Marking", _mark_closure_time_ms);
1414 }
1415 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
1416 #ifndef PRODUCT
1417 print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
1418 print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
1419 print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
1420 print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
1421 if (_num_cc_clears > 0) {
1422 print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
1423 }
1424 #endif
1425 print_stats(1, "Other", other_time_ms);
1426 print_stats(2, "Choose CSet",
1427 (_recorded_young_cset_choice_time_ms +
1428 _recorded_non_young_cset_choice_time_ms));
1429 print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
1430 print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
1431 print_stats(2, "Free CSet",
1432 (_recorded_young_free_cset_time_ms +
1433 _recorded_non_young_free_cset_time_ms));
1435 for (int i = 0; i < _aux_num; ++i) {
1436 if (_cur_aux_times_set[i]) {
1437 char buffer[96];
1438 sprintf(buffer, "Aux%d", i);
1439 print_stats(1, buffer, _cur_aux_times_ms[i]);
1440 }
1441 }
1442 }
1444 // Update the efficiency-since-mark vars.
1445 double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
1446 if (elapsed_ms < MIN_TIMER_GRANULARITY) {
1447 // This usually happens due to the timer not having the required
1448 // granularity. Some Linuxes are the usual culprits.
1449 // We'll just set it to something (arbitrarily) small.
1450 proc_ms = 1.0;
1451 }
1452 double cur_efficiency = (double) freed_bytes / proc_ms;
1454 bool new_in_marking_window = _in_marking_window;
1455 bool new_in_marking_window_im = false;
1456 if (during_initial_mark_pause()) {
1457 new_in_marking_window = true;
1458 new_in_marking_window_im = true;
1459 }
1461 if (_last_young_gc) {
1462 if (!last_pause_included_initial_mark) {
1463 ergo_verbose2(ErgoMixedGCs,
1464 "start mixed GCs",
1465 ergo_format_byte_perc("known garbage"),
1466 _known_garbage_bytes, _known_garbage_ratio * 100.0);
1467 set_gcs_are_young(false);
1468 } else {
1469 ergo_verbose0(ErgoMixedGCs,
1470 "do not start mixed GCs",
1471 ergo_format_reason("concurrent cycle is about to start"));
1472 }
1473 _last_young_gc = false;
1474 }
1476 if (!_last_gc_was_young) {
1477 if (_should_revert_to_young_gcs) {
1478 ergo_verbose2(ErgoMixedGCs,
1479 "end mixed GCs",
1480 ergo_format_reason("mixed GCs end requested")
1481 ergo_format_byte_perc("known garbage"),
1482 _known_garbage_bytes, _known_garbage_ratio * 100.0);
1483 set_gcs_are_young(true);
1484 } else if (_known_garbage_ratio < 0.05) {
1485 ergo_verbose3(ErgoMixedGCs,
1486 "end mixed GCs",
1487 ergo_format_reason("known garbage percent lower than threshold")
1488 ergo_format_byte_perc("known garbage")
1489 ergo_format_perc("threshold"),
1490 _known_garbage_bytes, _known_garbage_ratio * 100.0,
1491 0.05 * 100.0);
1492 set_gcs_are_young(true);
1493 } else if (adaptive_young_list_length() &&
1494 (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) {
1495 ergo_verbose5(ErgoMixedGCs,
1496 "end mixed GCs",
1497 ergo_format_reason("current GC efficiency lower than "
1498 "predicted young GC efficiency")
1499 ergo_format_double("GC efficiency factor")
1500 ergo_format_double("current GC efficiency")
1501 ergo_format_double("predicted young GC efficiency")
1502 ergo_format_byte_perc("known garbage"),
1503 get_gc_eff_factor(), cur_efficiency,
1504 predict_young_gc_eff(),
1505 _known_garbage_bytes, _known_garbage_ratio * 100.0);
1506 set_gcs_are_young(true);
1507 }
1508 }
1509 _should_revert_to_young_gcs = false;
1511 if (_last_gc_was_young && !_during_marking) {
1512 _young_gc_eff_seq->add(cur_efficiency);
1513 }
1515 _short_lived_surv_rate_group->start_adding_regions();
1516 // do that for any other surv rate groupsx
1518 if (update_stats) {
1519 double pause_time_ms = elapsed_ms;
1521 size_t diff = 0;
1522 if (_max_pending_cards >= _pending_cards)
1523 diff = _max_pending_cards - _pending_cards;
1524 _pending_card_diff_seq->add((double) diff);
1526 double cost_per_card_ms = 0.0;
1527 if (_pending_cards > 0) {
1528 cost_per_card_ms = update_rs_time / (double) _pending_cards;
1529 _cost_per_card_ms_seq->add(cost_per_card_ms);
1530 }
1532 size_t cards_scanned = _g1->cards_scanned();
1534 double cost_per_entry_ms = 0.0;
1535 if (cards_scanned > 10) {
1536 cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
1537 if (_last_gc_was_young) {
1538 _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1539 } else {
1540 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1541 }
1542 }
1544 if (_max_rs_lengths > 0) {
1545 double cards_per_entry_ratio =
1546 (double) cards_scanned / (double) _max_rs_lengths;
1547 if (_last_gc_was_young) {
1548 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1549 } else {
1550 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1551 }
1552 }
1554 // It turns out that, sometimes, _max_rs_lengths can get smaller
1555 // than _recorded_rs_lengths which causes rs_length_diff to get
1556 // very large and mess up the RSet length predictions. We'll be
1557 // defensive until we work out why this happens.
1558 size_t rs_length_diff = 0;
1559 if (_max_rs_lengths > _recorded_rs_lengths) {
1560 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1561 }
1562 _rs_length_diff_seq->add((double) rs_length_diff);
1564 size_t copied_bytes = surviving_bytes;
1565 double cost_per_byte_ms = 0.0;
1566 if (copied_bytes > 0) {
1567 cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
1568 if (_in_marking_window) {
1569 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1570 } else {
1571 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1572 }
1573 }
1575 double all_other_time_ms = pause_time_ms -
1576 (update_rs_time + scan_rs_time + obj_copy_time +
1577 _mark_closure_time_ms + termination_time);
1579 double young_other_time_ms = 0.0;
1580 if (young_cset_region_length() > 0) {
1581 young_other_time_ms =
1582 _recorded_young_cset_choice_time_ms +
1583 _recorded_young_free_cset_time_ms;
1584 _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1585 (double) young_cset_region_length());
1586 }
1587 double non_young_other_time_ms = 0.0;
1588 if (old_cset_region_length() > 0) {
1589 non_young_other_time_ms =
1590 _recorded_non_young_cset_choice_time_ms +
1591 _recorded_non_young_free_cset_time_ms;
1593 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1594 (double) old_cset_region_length());
1595 }
1597 double constant_other_time_ms = all_other_time_ms -
1598 (young_other_time_ms + non_young_other_time_ms);
1599 _constant_other_time_ms_seq->add(constant_other_time_ms);
1601 double survival_ratio = 0.0;
1602 if (_bytes_in_collection_set_before_gc > 0) {
1603 survival_ratio = (double) _bytes_copied_during_gc /
1604 (double) _bytes_in_collection_set_before_gc;
1605 }
1607 _pending_cards_seq->add((double) _pending_cards);
1608 _rs_lengths_seq->add((double) _max_rs_lengths);
1610 double expensive_region_limit_ms =
1611 (double) MaxGCPauseMillis - predict_constant_other_time_ms();
1612 if (expensive_region_limit_ms < 0.0) {
1613 // this means that the other time was predicted to be longer than
1614 // than the max pause time
1615 expensive_region_limit_ms = (double) MaxGCPauseMillis;
1616 }
1617 _expensive_region_limit_ms = expensive_region_limit_ms;
1618 }
1620 _in_marking_window = new_in_marking_window;
1621 _in_marking_window_im = new_in_marking_window_im;
1622 _free_regions_at_end_of_collection = _g1->free_regions();
1623 update_young_list_target_length();
1625 // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1626 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1627 adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
1629 assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
1630 }
1632 #define EXT_SIZE_FORMAT "%d%s"
1633 #define EXT_SIZE_PARAMS(bytes) \
1634 byte_size_in_proper_unit((bytes)), \
1635 proper_unit_for_byte_size((bytes))
1637 void G1CollectorPolicy::print_heap_transition() {
1638 if (PrintGCDetails) {
1639 YoungList* young_list = _g1->young_list();
1640 size_t eden_bytes = young_list->eden_used_bytes();
1641 size_t survivor_bytes = young_list->survivor_used_bytes();
1642 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1643 size_t used = _g1->used();
1644 size_t capacity = _g1->capacity();
1645 size_t eden_capacity =
1646 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1648 gclog_or_tty->print_cr(
1649 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1650 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1651 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1652 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1653 EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1654 EXT_SIZE_PARAMS(_prev_eden_capacity),
1655 EXT_SIZE_PARAMS(eden_bytes),
1656 EXT_SIZE_PARAMS(eden_capacity),
1657 EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1658 EXT_SIZE_PARAMS(survivor_bytes),
1659 EXT_SIZE_PARAMS(used_before_gc),
1660 EXT_SIZE_PARAMS(_capacity_before_gc),
1661 EXT_SIZE_PARAMS(used),
1662 EXT_SIZE_PARAMS(capacity));
1664 _prev_eden_capacity = eden_capacity;
1665 } else if (PrintGC) {
1666 _g1->print_size_transition(gclog_or_tty,
1667 _cur_collection_pause_used_at_start_bytes,
1668 _g1->used(), _g1->capacity());
1669 }
1670 }
1672 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1673 double update_rs_processed_buffers,
1674 double goal_ms) {
1675 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1676 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1678 if (G1UseAdaptiveConcRefinement) {
1679 const int k_gy = 3, k_gr = 6;
1680 const double inc_k = 1.1, dec_k = 0.9;
1682 int g = cg1r->green_zone();
1683 if (update_rs_time > goal_ms) {
1684 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
1685 } else {
1686 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1687 g = (int)MAX2(g * inc_k, g + 1.0);
1688 }
1689 }
1690 // Change the refinement threads params
1691 cg1r->set_green_zone(g);
1692 cg1r->set_yellow_zone(g * k_gy);
1693 cg1r->set_red_zone(g * k_gr);
1694 cg1r->reinitialize_threads();
1696 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1697 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1698 cg1r->yellow_zone());
1699 // Change the barrier params
1700 dcqs.set_process_completed_threshold(processing_threshold);
1701 dcqs.set_max_completed_queue(cg1r->red_zone());
1702 }
1704 int curr_queue_size = dcqs.completed_buffers_num();
1705 if (curr_queue_size >= cg1r->yellow_zone()) {
1706 dcqs.set_completed_queue_padding(curr_queue_size);
1707 } else {
1708 dcqs.set_completed_queue_padding(0);
1709 }
1710 dcqs.notify_if_necessary();
1711 }
1713 double
1714 G1CollectorPolicy::
1715 predict_young_collection_elapsed_time_ms(size_t adjustment) {
1716 guarantee( adjustment == 0 || adjustment == 1, "invariant" );
1718 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1719 size_t young_num = g1h->young_list()->length();
1720 if (young_num == 0)
1721 return 0.0;
1723 young_num += adjustment;
1724 size_t pending_cards = predict_pending_cards();
1725 size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
1726 predict_rs_length_diff();
1727 size_t card_num;
1728 if (gcs_are_young()) {
1729 card_num = predict_young_card_num(rs_lengths);
1730 } else {
1731 card_num = predict_non_young_card_num(rs_lengths);
1732 }
1733 size_t young_byte_size = young_num * HeapRegion::GrainBytes;
1734 double accum_yg_surv_rate =
1735 _short_lived_surv_rate_group->accum_surv_rate(adjustment);
1737 size_t bytes_to_copy =
1738 (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
1740 return
1741 predict_rs_update_time_ms(pending_cards) +
1742 predict_rs_scan_time_ms(card_num) +
1743 predict_object_copy_time_ms(bytes_to_copy) +
1744 predict_young_other_time_ms(young_num) +
1745 predict_constant_other_time_ms();
1746 }
1748 double
1749 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1750 size_t rs_length = predict_rs_length_diff();
1751 size_t card_num;
1752 if (gcs_are_young()) {
1753 card_num = predict_young_card_num(rs_length);
1754 } else {
1755 card_num = predict_non_young_card_num(rs_length);
1756 }
1757 return predict_base_elapsed_time_ms(pending_cards, card_num);
1758 }
1760 double
1761 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1762 size_t scanned_cards) {
1763 return
1764 predict_rs_update_time_ms(pending_cards) +
1765 predict_rs_scan_time_ms(scanned_cards) +
1766 predict_constant_other_time_ms();
1767 }
1769 double
1770 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1771 bool young) {
1772 size_t rs_length = hr->rem_set()->occupied();
1773 size_t card_num;
1774 if (gcs_are_young()) {
1775 card_num = predict_young_card_num(rs_length);
1776 } else {
1777 card_num = predict_non_young_card_num(rs_length);
1778 }
1779 size_t bytes_to_copy = predict_bytes_to_copy(hr);
1781 double region_elapsed_time_ms =
1782 predict_rs_scan_time_ms(card_num) +
1783 predict_object_copy_time_ms(bytes_to_copy);
1785 if (young)
1786 region_elapsed_time_ms += predict_young_other_time_ms(1);
1787 else
1788 region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1790 return region_elapsed_time_ms;
1791 }
1793 size_t
1794 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1795 size_t bytes_to_copy;
1796 if (hr->is_marked())
1797 bytes_to_copy = hr->max_live_bytes();
1798 else {
1799 guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
1800 "invariant" );
1801 int age = hr->age_in_surv_rate_group();
1802 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1803 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1804 }
1806 return bytes_to_copy;
1807 }
1809 void
1810 G1CollectorPolicy::init_cset_region_lengths(size_t eden_cset_region_length,
1811 size_t survivor_cset_region_length) {
1812 _eden_cset_region_length = eden_cset_region_length;
1813 _survivor_cset_region_length = survivor_cset_region_length;
1814 _old_cset_region_length = 0;
1815 }
1817 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1818 _recorded_rs_lengths = rs_lengths;
1819 }
1821 void G1CollectorPolicy::check_if_region_is_too_expensive(double
1822 predicted_time_ms) {
1823 // I don't think we need to do this when in young GC mode since
1824 // marking will be initiated next time we hit the soft limit anyway...
1825 if (predicted_time_ms > _expensive_region_limit_ms) {
1826 ergo_verbose2(ErgoMixedGCs,
1827 "request mixed GCs end",
1828 ergo_format_reason("predicted region time higher than threshold")
1829 ergo_format_ms("predicted region time")
1830 ergo_format_ms("threshold"),
1831 predicted_time_ms, _expensive_region_limit_ms);
1832 // no point in doing another mixed GC
1833 _should_revert_to_young_gcs = true;
1834 }
1835 }
1837 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1838 double elapsed_ms) {
1839 _recent_gc_times_ms->add(elapsed_ms);
1840 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1841 _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1842 }
1844 size_t G1CollectorPolicy::expansion_amount() {
1845 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1846 double threshold = _gc_overhead_perc;
1847 if (recent_gc_overhead > threshold) {
1848 // We will double the existing space, or take
1849 // G1ExpandByPercentOfAvailable % of the available expansion
1850 // space, whichever is smaller, bounded below by a minimum
1851 // expansion (unless that's all that's left.)
1852 const size_t min_expand_bytes = 1*M;
1853 size_t reserved_bytes = _g1->max_capacity();
1854 size_t committed_bytes = _g1->capacity();
1855 size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1856 size_t expand_bytes;
1857 size_t expand_bytes_via_pct =
1858 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1859 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1860 expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1861 expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1863 ergo_verbose5(ErgoHeapSizing,
1864 "attempt heap expansion",
1865 ergo_format_reason("recent GC overhead higher than "
1866 "threshold after GC")
1867 ergo_format_perc("recent GC overhead")
1868 ergo_format_perc("threshold")
1869 ergo_format_byte("uncommitted")
1870 ergo_format_byte_perc("calculated expansion amount"),
1871 recent_gc_overhead, threshold,
1872 uncommitted_bytes,
1873 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1875 return expand_bytes;
1876 } else {
1877 return 0;
1878 }
1879 }
1881 class CountCSClosure: public HeapRegionClosure {
1882 G1CollectorPolicy* _g1_policy;
1883 public:
1884 CountCSClosure(G1CollectorPolicy* g1_policy) :
1885 _g1_policy(g1_policy) {}
1886 bool doHeapRegion(HeapRegion* r) {
1887 _g1_policy->_bytes_in_collection_set_before_gc += r->used();
1888 return false;
1889 }
1890 };
1892 void G1CollectorPolicy::count_CS_bytes_used() {
1893 CountCSClosure cs_closure(this);
1894 _g1->collection_set_iterate(&cs_closure);
1895 }
1897 void G1CollectorPolicy::print_summary(int level,
1898 const char* str,
1899 NumberSeq* seq) const {
1900 double sum = seq->sum();
1901 LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
1902 str, sum / 1000.0, seq->avg());
1903 }
1905 void G1CollectorPolicy::print_summary_sd(int level,
1906 const char* str,
1907 NumberSeq* seq) const {
1908 print_summary(level, str, seq);
1909 LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
1910 seq->num(), seq->sd(), seq->maximum());
1911 }
1913 void G1CollectorPolicy::check_other_times(int level,
1914 NumberSeq* other_times_ms,
1915 NumberSeq* calc_other_times_ms) const {
1916 bool should_print = false;
1917 LineBuffer buf(level + 2);
1919 double max_sum = MAX2(fabs(other_times_ms->sum()),
1920 fabs(calc_other_times_ms->sum()));
1921 double min_sum = MIN2(fabs(other_times_ms->sum()),
1922 fabs(calc_other_times_ms->sum()));
1923 double sum_ratio = max_sum / min_sum;
1924 if (sum_ratio > 1.1) {
1925 should_print = true;
1926 buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
1927 }
1929 double max_avg = MAX2(fabs(other_times_ms->avg()),
1930 fabs(calc_other_times_ms->avg()));
1931 double min_avg = MIN2(fabs(other_times_ms->avg()),
1932 fabs(calc_other_times_ms->avg()));
1933 double avg_ratio = max_avg / min_avg;
1934 if (avg_ratio > 1.1) {
1935 should_print = true;
1936 buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
1937 }
1939 if (other_times_ms->sum() < -0.01) {
1940 buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
1941 }
1943 if (other_times_ms->avg() < -0.01) {
1944 buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
1945 }
1947 if (calc_other_times_ms->sum() < -0.01) {
1948 should_print = true;
1949 buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
1950 }
1952 if (calc_other_times_ms->avg() < -0.01) {
1953 should_print = true;
1954 buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
1955 }
1957 if (should_print)
1958 print_summary(level, "Other(Calc)", calc_other_times_ms);
1959 }
1961 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
1962 bool parallel = G1CollectedHeap::use_parallel_gc_threads();
1963 MainBodySummary* body_summary = summary->main_body_summary();
1964 if (summary->get_total_seq()->num() > 0) {
1965 print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
1966 if (body_summary != NULL) {
1967 print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
1968 if (parallel) {
1969 print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
1970 print_summary(2, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1971 print_summary(2, "Mark Stack Scanning", body_summary->get_mark_stack_scan_seq());
1972 print_summary(2, "Update RS", body_summary->get_update_rs_seq());
1973 print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
1974 print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
1975 print_summary(2, "Termination", body_summary->get_termination_seq());
1976 print_summary(2, "Parallel Other", body_summary->get_parallel_other_seq());
1977 {
1978 NumberSeq* other_parts[] = {
1979 body_summary->get_ext_root_scan_seq(),
1980 body_summary->get_mark_stack_scan_seq(),
1981 body_summary->get_update_rs_seq(),
1982 body_summary->get_scan_rs_seq(),
1983 body_summary->get_obj_copy_seq(),
1984 body_summary->get_termination_seq()
1985 };
1986 NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
1987 6, other_parts);
1988 check_other_times(2, body_summary->get_parallel_other_seq(),
1989 &calc_other_times_ms);
1990 }
1991 } else {
1992 print_summary(1, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());
1993 print_summary(1, "Mark Stack Scanning", body_summary->get_mark_stack_scan_seq());
1994 print_summary(1, "Update RS", body_summary->get_update_rs_seq());
1995 print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
1996 print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
1997 }
1998 }
1999 print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
2000 print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
2001 print_summary(1, "Other", summary->get_other_seq());
2002 {
2003 if (body_summary != NULL) {
2004 NumberSeq calc_other_times_ms;
2005 if (parallel) {
2006 // parallel
2007 NumberSeq* other_parts[] = {
2008 body_summary->get_satb_drain_seq(),
2009 body_summary->get_parallel_seq(),
2010 body_summary->get_clear_ct_seq()
2011 };
2012 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2013 3, other_parts);
2014 } else {
2015 // serial
2016 NumberSeq* other_parts[] = {
2017 body_summary->get_satb_drain_seq(),
2018 body_summary->get_update_rs_seq(),
2019 body_summary->get_ext_root_scan_seq(),
2020 body_summary->get_mark_stack_scan_seq(),
2021 body_summary->get_scan_rs_seq(),
2022 body_summary->get_obj_copy_seq()
2023 };
2024 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
2025 6, other_parts);
2026 }
2027 check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
2028 }
2029 }
2030 } else {
2031 LineBuffer(1).append_and_print_cr("none");
2032 }
2033 LineBuffer(0).append_and_print_cr("");
2034 }
2036 void G1CollectorPolicy::print_tracing_info() const {
2037 if (TraceGen0Time) {
2038 gclog_or_tty->print_cr("ALL PAUSES");
2039 print_summary_sd(0, "Total", _all_pause_times_ms);
2040 gclog_or_tty->print_cr("");
2041 gclog_or_tty->print_cr("");
2042 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num);
2043 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num);
2044 gclog_or_tty->print_cr("");
2046 gclog_or_tty->print_cr("EVACUATION PAUSES");
2047 print_summary(_summary);
2049 gclog_or_tty->print_cr("MISC");
2050 print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
2051 print_summary_sd(0, "Yields", _all_yield_times_ms);
2052 for (int i = 0; i < _aux_num; ++i) {
2053 if (_all_aux_times_ms[i].num() > 0) {
2054 char buffer[96];
2055 sprintf(buffer, "Aux%d", i);
2056 print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
2057 }
2058 }
2059 }
2060 if (TraceGen1Time) {
2061 if (_all_full_gc_times_ms->num() > 0) {
2062 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2063 _all_full_gc_times_ms->num(),
2064 _all_full_gc_times_ms->sum() / 1000.0);
2065 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
2066 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
2067 _all_full_gc_times_ms->sd(),
2068 _all_full_gc_times_ms->maximum());
2069 }
2070 }
2071 }
2073 void G1CollectorPolicy::print_yg_surv_rate_info() const {
2074 #ifndef PRODUCT
2075 _short_lived_surv_rate_group->print_surv_rate_summary();
2076 // add this call for any other surv rate groups
2077 #endif // PRODUCT
2078 }
2080 #ifndef PRODUCT
2081 // for debugging, bit of a hack...
2082 static char*
2083 region_num_to_mbs(int length) {
2084 static char buffer[64];
2085 double bytes = (double) (length * HeapRegion::GrainBytes);
2086 double mbs = bytes / (double) (1024 * 1024);
2087 sprintf(buffer, "%7.2lfMB", mbs);
2088 return buffer;
2089 }
2090 #endif // PRODUCT
2092 size_t G1CollectorPolicy::max_regions(int purpose) {
2093 switch (purpose) {
2094 case GCAllocForSurvived:
2095 return _max_survivor_regions;
2096 case GCAllocForTenured:
2097 return REGIONS_UNLIMITED;
2098 default:
2099 ShouldNotReachHere();
2100 return REGIONS_UNLIMITED;
2101 };
2102 }
2104 void G1CollectorPolicy::update_max_gc_locker_expansion() {
2105 size_t expansion_region_num = 0;
2106 if (GCLockerEdenExpansionPercent > 0) {
2107 double perc = (double) GCLockerEdenExpansionPercent / 100.0;
2108 double expansion_region_num_d = perc * (double) _young_list_target_length;
2109 // We use ceiling so that if expansion_region_num_d is > 0.0 (but
2110 // less than 1.0) we'll get 1.
2111 expansion_region_num = (size_t) ceil(expansion_region_num_d);
2112 } else {
2113 assert(expansion_region_num == 0, "sanity");
2114 }
2115 _young_list_max_length = _young_list_target_length + expansion_region_num;
2116 assert(_young_list_target_length <= _young_list_max_length, "post-condition");
2117 }
2119 // Calculates survivor space parameters.
2120 void G1CollectorPolicy::update_survivors_policy() {
2121 double max_survivor_regions_d =
2122 (double) _young_list_target_length / (double) SurvivorRatio;
2123 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
2124 // smaller than 1.0) we'll get 1.
2125 _max_survivor_regions = (size_t) ceil(max_survivor_regions_d);
2127 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
2128 HeapRegion::GrainWords * _max_survivor_regions);
2129 }
2131 #ifndef PRODUCT
2132 class HRSortIndexIsOKClosure: public HeapRegionClosure {
2133 CollectionSetChooser* _chooser;
2134 public:
2135 HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
2136 _chooser(chooser) {}
2138 bool doHeapRegion(HeapRegion* r) {
2139 if (!r->continuesHumongous()) {
2140 assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
2141 }
2142 return false;
2143 }
2144 };
2146 bool G1CollectorPolicy::assertMarkedBytesDataOK() {
2147 HRSortIndexIsOKClosure cl(_collectionSetChooser);
2148 _g1->heap_region_iterate(&cl);
2149 return true;
2150 }
2151 #endif
2153 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
2154 GCCause::Cause gc_cause) {
2155 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2156 if (!during_cycle) {
2157 ergo_verbose1(ErgoConcCycles,
2158 "request concurrent cycle initiation",
2159 ergo_format_reason("requested by GC cause")
2160 ergo_format_str("GC cause"),
2161 GCCause::to_string(gc_cause));
2162 set_initiate_conc_mark_if_possible();
2163 return true;
2164 } else {
2165 ergo_verbose1(ErgoConcCycles,
2166 "do not request concurrent cycle initiation",
2167 ergo_format_reason("concurrent cycle already in progress")
2168 ergo_format_str("GC cause"),
2169 GCCause::to_string(gc_cause));
2170 return false;
2171 }
2172 }
2174 void
2175 G1CollectorPolicy::decide_on_conc_mark_initiation() {
2176 // We are about to decide on whether this pause will be an
2177 // initial-mark pause.
2179 // First, during_initial_mark_pause() should not be already set. We
2180 // will set it here if we have to. However, it should be cleared by
2181 // the end of the pause (it's only set for the duration of an
2182 // initial-mark pause).
2183 assert(!during_initial_mark_pause(), "pre-condition");
2185 if (initiate_conc_mark_if_possible()) {
2186 // We had noticed on a previous pause that the heap occupancy has
2187 // gone over the initiating threshold and we should start a
2188 // concurrent marking cycle. So we might initiate one.
2190 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
2191 if (!during_cycle) {
2192 // The concurrent marking thread is not "during a cycle", i.e.,
2193 // it has completed the last one. So we can go ahead and
2194 // initiate a new cycle.
2196 set_during_initial_mark_pause();
2197 // We do not allow mixed GCs during marking.
2198 if (!gcs_are_young()) {
2199 set_gcs_are_young(true);
2200 ergo_verbose0(ErgoMixedGCs,
2201 "end mixed GCs",
2202 ergo_format_reason("concurrent cycle is about to start"));
2203 }
2205 // And we can now clear initiate_conc_mark_if_possible() as
2206 // we've already acted on it.
2207 clear_initiate_conc_mark_if_possible();
2209 ergo_verbose0(ErgoConcCycles,
2210 "initiate concurrent cycle",
2211 ergo_format_reason("concurrent cycle initiation requested"));
2212 } else {
2213 // The concurrent marking thread is still finishing up the
2214 // previous cycle. If we start one right now the two cycles
2215 // overlap. In particular, the concurrent marking thread might
2216 // be in the process of clearing the next marking bitmap (which
2217 // we will use for the next cycle if we start one). Starting a
2218 // cycle now will be bad given that parts of the marking
2219 // information might get cleared by the marking thread. And we
2220 // cannot wait for the marking thread to finish the cycle as it
2221 // periodically yields while clearing the next marking bitmap
2222 // and, if it's in a yield point, it's waiting for us to
2223 // finish. So, at this point we will not start a cycle and we'll
2224 // let the concurrent marking thread complete the last one.
2225 ergo_verbose0(ErgoConcCycles,
2226 "do not initiate concurrent cycle",
2227 ergo_format_reason("concurrent cycle already in progress"));
2228 }
2229 }
2230 }
2232 class KnownGarbageClosure: public HeapRegionClosure {
2233 CollectionSetChooser* _hrSorted;
2235 public:
2236 KnownGarbageClosure(CollectionSetChooser* hrSorted) :
2237 _hrSorted(hrSorted)
2238 {}
2240 bool doHeapRegion(HeapRegion* r) {
2241 // We only include humongous regions in collection
2242 // sets when concurrent mark shows that their contained object is
2243 // unreachable.
2245 // Do we have any marking information for this region?
2246 if (r->is_marked()) {
2247 // We don't include humongous regions in collection
2248 // sets because we collect them immediately at the end of a marking
2249 // cycle. We also don't include young regions because we *must*
2250 // include them in the next collection pause.
2251 if (!r->isHumongous() && !r->is_young()) {
2252 _hrSorted->addMarkedHeapRegion(r);
2253 }
2254 }
2255 return false;
2256 }
2257 };
2259 class ParKnownGarbageHRClosure: public HeapRegionClosure {
2260 CollectionSetChooser* _hrSorted;
2261 jint _marked_regions_added;
2262 jint _chunk_size;
2263 jint _cur_chunk_idx;
2264 jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
2265 int _worker;
2266 int _invokes;
2268 void get_new_chunk() {
2269 _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
2270 _cur_chunk_end = _cur_chunk_idx + _chunk_size;
2271 }
2272 void add_region(HeapRegion* r) {
2273 if (_cur_chunk_idx == _cur_chunk_end) {
2274 get_new_chunk();
2275 }
2276 assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
2277 _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
2278 _marked_regions_added++;
2279 _cur_chunk_idx++;
2280 }
2282 public:
2283 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
2284 jint chunk_size,
2285 int worker) :
2286 _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
2287 _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
2288 _invokes(0)
2289 {}
2291 bool doHeapRegion(HeapRegion* r) {
2292 // We only include humongous regions in collection
2293 // sets when concurrent mark shows that their contained object is
2294 // unreachable.
2295 _invokes++;
2297 // Do we have any marking information for this region?
2298 if (r->is_marked()) {
2299 // We don't include humongous regions in collection
2300 // sets because we collect them immediately at the end of a marking
2301 // cycle.
2302 // We also do not include young regions in collection sets
2303 if (!r->isHumongous() && !r->is_young()) {
2304 add_region(r);
2305 }
2306 }
2307 return false;
2308 }
2309 jint marked_regions_added() { return _marked_regions_added; }
2310 int invokes() { return _invokes; }
2311 };
2313 class ParKnownGarbageTask: public AbstractGangTask {
2314 CollectionSetChooser* _hrSorted;
2315 jint _chunk_size;
2316 G1CollectedHeap* _g1;
2317 public:
2318 ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
2319 AbstractGangTask("ParKnownGarbageTask"),
2320 _hrSorted(hrSorted), _chunk_size(chunk_size),
2321 _g1(G1CollectedHeap::heap())
2322 {}
2324 void work(int i) {
2325 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
2326 // Back to zero for the claim value.
2327 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
2328 _g1->workers()->active_workers(),
2329 HeapRegion::InitialClaimValue);
2330 jint regions_added = parKnownGarbageCl.marked_regions_added();
2331 _hrSorted->incNumMarkedHeapRegions(regions_added);
2332 if (G1PrintParCleanupStats) {
2333 gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
2334 i, parKnownGarbageCl.invokes(), regions_added);
2335 }
2336 }
2337 };
2339 void
2340 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
2341 double start_sec;
2342 if (G1PrintParCleanupStats) {
2343 start_sec = os::elapsedTime();
2344 }
2346 _collectionSetChooser->clearMarkedHeapRegions();
2347 double clear_marked_end_sec;
2348 if (G1PrintParCleanupStats) {
2349 clear_marked_end_sec = os::elapsedTime();
2350 gclog_or_tty->print_cr(" clear marked regions: %8.3f ms.",
2351 (clear_marked_end_sec - start_sec) * 1000.0);
2352 }
2354 if (G1CollectedHeap::use_parallel_gc_threads()) {
2355 const size_t OverpartitionFactor = 4;
2356 size_t WorkUnit;
2357 // The use of MinChunkSize = 8 in the original code
2358 // causes some assertion failures when the total number of
2359 // region is less than 8. The code here tries to fix that.
2360 // Should the original code also be fixed?
2361 if (no_of_gc_threads > 0) {
2362 const size_t MinWorkUnit =
2363 MAX2(_g1->n_regions() / no_of_gc_threads, (size_t) 1U);
2364 WorkUnit =
2365 MAX2(_g1->n_regions() / (no_of_gc_threads * OverpartitionFactor),
2366 MinWorkUnit);
2367 } else {
2368 assert(no_of_gc_threads > 0,
2369 "The active gc workers should be greater than 0");
2370 // In a product build do something reasonable to avoid a crash.
2371 const size_t MinWorkUnit =
2372 MAX2(_g1->n_regions() / ParallelGCThreads, (size_t) 1U);
2373 WorkUnit =
2374 MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
2375 MinWorkUnit);
2376 }
2377 _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
2378 WorkUnit);
2379 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
2380 (int) WorkUnit);
2381 _g1->workers()->run_task(&parKnownGarbageTask);
2383 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2384 "sanity check");
2385 } else {
2386 KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
2387 _g1->heap_region_iterate(&knownGarbagecl);
2388 }
2389 double known_garbage_end_sec;
2390 if (G1PrintParCleanupStats) {
2391 known_garbage_end_sec = os::elapsedTime();
2392 gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
2393 (known_garbage_end_sec - clear_marked_end_sec) * 1000.0);
2394 }
2396 _collectionSetChooser->sortMarkedHeapRegions();
2397 double end_sec = os::elapsedTime();
2398 if (G1PrintParCleanupStats) {
2399 gclog_or_tty->print_cr(" sorting: %8.3f ms.",
2400 (end_sec - known_garbage_end_sec) * 1000.0);
2401 }
2403 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
2404 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
2405 _cur_mark_stop_world_time_ms += elapsed_time_ms;
2406 _prev_collection_pause_end_ms += elapsed_time_ms;
2407 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
2408 }
2410 // Add the heap region at the head of the non-incremental collection set
2411 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
2412 assert(_inc_cset_build_state == Active, "Precondition");
2413 assert(!hr->is_young(), "non-incremental add of young region");
2415 if (_g1->mark_in_progress())
2416 _g1->concurrent_mark()->registerCSetRegion(hr);
2418 assert(!hr->in_collection_set(), "should not already be in the CSet");
2419 hr->set_in_collection_set(true);
2420 hr->set_next_in_collection_set(_collection_set);
2421 _collection_set = hr;
2422 _collection_set_bytes_used_before += hr->used();
2423 _g1->register_region_with_in_cset_fast_test(hr);
2424 size_t rs_length = hr->rem_set()->occupied();
2425 _recorded_rs_lengths += rs_length;
2426 _old_cset_region_length += 1;
2427 }
2429 // Initialize the per-collection-set information
2430 void G1CollectorPolicy::start_incremental_cset_building() {
2431 assert(_inc_cset_build_state == Inactive, "Precondition");
2433 _inc_cset_head = NULL;
2434 _inc_cset_tail = NULL;
2435 _inc_cset_bytes_used_before = 0;
2437 _inc_cset_max_finger = 0;
2438 _inc_cset_recorded_rs_lengths = 0;
2439 _inc_cset_predicted_elapsed_time_ms = 0;
2440 _inc_cset_build_state = Active;
2441 }
2443 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
2444 // This routine is used when:
2445 // * adding survivor regions to the incremental cset at the end of an
2446 // evacuation pause,
2447 // * adding the current allocation region to the incremental cset
2448 // when it is retired, and
2449 // * updating existing policy information for a region in the
2450 // incremental cset via young list RSet sampling.
2451 // Therefore this routine may be called at a safepoint by the
2452 // VM thread, or in-between safepoints by mutator threads (when
2453 // retiring the current allocation region) or a concurrent
2454 // refine thread (RSet sampling).
2456 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
2457 size_t used_bytes = hr->used();
2459 _inc_cset_recorded_rs_lengths += rs_length;
2460 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
2462 _inc_cset_bytes_used_before += used_bytes;
2464 // Cache the values we have added to the aggregated informtion
2465 // in the heap region in case we have to remove this region from
2466 // the incremental collection set, or it is updated by the
2467 // rset sampling code
2468 hr->set_recorded_rs_length(rs_length);
2469 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
2470 }
2472 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
2473 // This routine is currently only called as part of the updating of
2474 // existing policy information for regions in the incremental cset that
2475 // is performed by the concurrent refine thread(s) as part of young list
2476 // RSet sampling. Therefore we should not be at a safepoint.
2478 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
2479 assert(hr->is_young(), "it should be");
2481 size_t used_bytes = hr->used();
2482 size_t old_rs_length = hr->recorded_rs_length();
2483 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
2485 // Subtract the old recorded/predicted policy information for
2486 // the given heap region from the collection set info.
2487 _inc_cset_recorded_rs_lengths -= old_rs_length;
2488 _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
2490 _inc_cset_bytes_used_before -= used_bytes;
2492 // Clear the values cached in the heap region
2493 hr->set_recorded_rs_length(0);
2494 hr->set_predicted_elapsed_time_ms(0);
2495 }
2497 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
2498 // Update the collection set information that is dependent on the new RS length
2499 assert(hr->is_young(), "Precondition");
2501 remove_from_incremental_cset_info(hr);
2502 add_to_incremental_cset_info(hr, new_rs_length);
2503 }
2505 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
2506 assert(hr->is_young(), "invariant");
2507 assert(hr->young_index_in_cset() > -1, "should have already been set");
2508 assert(_inc_cset_build_state == Active, "Precondition");
2510 // We need to clear and set the cached recorded/cached collection set
2511 // information in the heap region here (before the region gets added
2512 // to the collection set). An individual heap region's cached values
2513 // are calculated, aggregated with the policy collection set info,
2514 // and cached in the heap region here (initially) and (subsequently)
2515 // by the Young List sampling code.
2517 size_t rs_length = hr->rem_set()->occupied();
2518 add_to_incremental_cset_info(hr, rs_length);
2520 HeapWord* hr_end = hr->end();
2521 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
2523 assert(!hr->in_collection_set(), "invariant");
2524 hr->set_in_collection_set(true);
2525 assert( hr->next_in_collection_set() == NULL, "invariant");
2527 _g1->register_region_with_in_cset_fast_test(hr);
2528 }
2530 // Add the region at the RHS of the incremental cset
2531 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
2532 // We should only ever be appending survivors at the end of a pause
2533 assert( hr->is_survivor(), "Logic");
2535 // Do the 'common' stuff
2536 add_region_to_incremental_cset_common(hr);
2538 // Now add the region at the right hand side
2539 if (_inc_cset_tail == NULL) {
2540 assert(_inc_cset_head == NULL, "invariant");
2541 _inc_cset_head = hr;
2542 } else {
2543 _inc_cset_tail->set_next_in_collection_set(hr);
2544 }
2545 _inc_cset_tail = hr;
2546 }
2548 // Add the region to the LHS of the incremental cset
2549 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2550 // Survivors should be added to the RHS at the end of a pause
2551 assert(!hr->is_survivor(), "Logic");
2553 // Do the 'common' stuff
2554 add_region_to_incremental_cset_common(hr);
2556 // Add the region at the left hand side
2557 hr->set_next_in_collection_set(_inc_cset_head);
2558 if (_inc_cset_head == NULL) {
2559 assert(_inc_cset_tail == NULL, "Invariant");
2560 _inc_cset_tail = hr;
2561 }
2562 _inc_cset_head = hr;
2563 }
2565 #ifndef PRODUCT
2566 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2567 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2569 st->print_cr("\nCollection_set:");
2570 HeapRegion* csr = list_head;
2571 while (csr != NULL) {
2572 HeapRegion* next = csr->next_in_collection_set();
2573 assert(csr->in_collection_set(), "bad CS");
2574 st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
2575 "age: %4d, y: %d, surv: %d",
2576 csr->bottom(), csr->end(),
2577 csr->top(),
2578 csr->prev_top_at_mark_start(),
2579 csr->next_top_at_mark_start(),
2580 csr->top_at_conc_mark_count(),
2581 csr->age_in_surv_rate_group_cond(),
2582 csr->is_young(),
2583 csr->is_survivor());
2584 csr = next;
2585 }
2586 }
2587 #endif // !PRODUCT
2589 void G1CollectorPolicy::choose_collection_set(double target_pause_time_ms) {
2590 // Set this here - in case we're not doing young collections.
2591 double non_young_start_time_sec = os::elapsedTime();
2593 YoungList* young_list = _g1->young_list();
2595 guarantee(target_pause_time_ms > 0.0,
2596 err_msg("target_pause_time_ms = %1.6lf should be positive",
2597 target_pause_time_ms));
2598 guarantee(_collection_set == NULL, "Precondition");
2600 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2601 double predicted_pause_time_ms = base_time_ms;
2603 double time_remaining_ms = target_pause_time_ms - base_time_ms;
2605 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2606 "start choosing CSet",
2607 ergo_format_ms("predicted base time")
2608 ergo_format_ms("remaining time")
2609 ergo_format_ms("target pause time"),
2610 base_time_ms, time_remaining_ms, target_pause_time_ms);
2612 // the 10% and 50% values are arbitrary...
2613 double threshold = 0.10 * target_pause_time_ms;
2614 if (time_remaining_ms < threshold) {
2615 double prev_time_remaining_ms = time_remaining_ms;
2616 time_remaining_ms = 0.50 * target_pause_time_ms;
2617 ergo_verbose3(ErgoCSetConstruction,
2618 "adjust remaining time",
2619 ergo_format_reason("remaining time lower than threshold")
2620 ergo_format_ms("remaining time")
2621 ergo_format_ms("threshold")
2622 ergo_format_ms("adjusted remaining time"),
2623 prev_time_remaining_ms, threshold, time_remaining_ms);
2624 }
2626 size_t expansion_bytes = _g1->expansion_regions() * HeapRegion::GrainBytes;
2628 HeapRegion* hr;
2629 double young_start_time_sec = os::elapsedTime();
2631 _collection_set_bytes_used_before = 0;
2632 _last_gc_was_young = gcs_are_young() ? true : false;
2634 if (_last_gc_was_young) {
2635 ++_young_pause_num;
2636 } else {
2637 ++_mixed_pause_num;
2638 }
2640 // The young list is laid with the survivor regions from the previous
2641 // pause are appended to the RHS of the young list, i.e.
2642 // [Newly Young Regions ++ Survivors from last pause].
2644 size_t survivor_region_length = young_list->survivor_length();
2645 size_t eden_region_length = young_list->length() - survivor_region_length;
2646 init_cset_region_lengths(eden_region_length, survivor_region_length);
2647 hr = young_list->first_survivor_region();
2648 while (hr != NULL) {
2649 assert(hr->is_survivor(), "badly formed young list");
2650 hr->set_young();
2651 hr = hr->get_next_young_region();
2652 }
2654 // Clear the fields that point to the survivor list - they are all young now.
2655 young_list->clear_survivors();
2657 if (_g1->mark_in_progress())
2658 _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
2660 _collection_set = _inc_cset_head;
2661 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2662 time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
2663 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
2665 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
2666 "add young regions to CSet",
2667 ergo_format_region("eden")
2668 ergo_format_region("survivors")
2669 ergo_format_ms("predicted young region time"),
2670 eden_region_length, survivor_region_length,
2671 _inc_cset_predicted_elapsed_time_ms);
2673 // The number of recorded young regions is the incremental
2674 // collection set's current size
2675 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2677 double young_end_time_sec = os::elapsedTime();
2678 _recorded_young_cset_choice_time_ms =
2679 (young_end_time_sec - young_start_time_sec) * 1000.0;
2681 // We are doing young collections so reset this.
2682 non_young_start_time_sec = young_end_time_sec;
2684 if (!gcs_are_young()) {
2685 bool should_continue = true;
2686 NumberSeq seq;
2687 double avg_prediction = 100000000000000000.0; // something very large
2689 double prev_predicted_pause_time_ms = predicted_pause_time_ms;
2690 do {
2691 // Note that add_old_region_to_cset() increments the
2692 // _old_cset_region_length field and cset_region_length() returns the
2693 // sum of _eden_cset_region_length, _survivor_cset_region_length, and
2694 // _old_cset_region_length. So, as old regions are added to the
2695 // CSet, _old_cset_region_length will be incremented and
2696 // cset_region_length(), which is used below, will always reflect
2697 // the the total number of regions added up to this point to the CSet.
2699 hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
2700 avg_prediction);
2701 if (hr != NULL) {
2702 _g1->old_set_remove(hr);
2703 double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
2704 time_remaining_ms -= predicted_time_ms;
2705 predicted_pause_time_ms += predicted_time_ms;
2706 add_old_region_to_cset(hr);
2707 seq.add(predicted_time_ms);
2708 avg_prediction = seq.avg() + seq.sd();
2709 }
2711 should_continue = true;
2712 if (hr == NULL) {
2713 // No need for an ergo verbose message here,
2714 // getNextMarkRegion() does this when it returns NULL.
2715 should_continue = false;
2716 } else {
2717 if (adaptive_young_list_length()) {
2718 if (time_remaining_ms < 0.0) {
2719 ergo_verbose1(ErgoCSetConstruction,
2720 "stop adding old regions to CSet",
2721 ergo_format_reason("remaining time is lower than 0")
2722 ergo_format_ms("remaining time"),
2723 time_remaining_ms);
2724 should_continue = false;
2725 }
2726 } else {
2727 if (cset_region_length() >= _young_list_fixed_length) {
2728 ergo_verbose2(ErgoCSetConstruction,
2729 "stop adding old regions to CSet",
2730 ergo_format_reason("CSet length reached target")
2731 ergo_format_region("CSet")
2732 ergo_format_region("young target"),
2733 cset_region_length(), _young_list_fixed_length);
2734 should_continue = false;
2735 }
2736 }
2737 }
2738 } while (should_continue);
2740 if (!adaptive_young_list_length() &&
2741 cset_region_length() < _young_list_fixed_length) {
2742 ergo_verbose2(ErgoCSetConstruction,
2743 "request mixed GCs end",
2744 ergo_format_reason("CSet length lower than target")
2745 ergo_format_region("CSet")
2746 ergo_format_region("young target"),
2747 cset_region_length(), _young_list_fixed_length);
2748 _should_revert_to_young_gcs = true;
2749 }
2751 ergo_verbose2(ErgoCSetConstruction | ErgoHigh,
2752 "add old regions to CSet",
2753 ergo_format_region("old")
2754 ergo_format_ms("predicted old region time"),
2755 old_cset_region_length(),
2756 predicted_pause_time_ms - prev_predicted_pause_time_ms);
2757 }
2759 stop_incremental_cset_building();
2761 count_CS_bytes_used();
2763 ergo_verbose5(ErgoCSetConstruction,
2764 "finish choosing CSet",
2765 ergo_format_region("eden")
2766 ergo_format_region("survivors")
2767 ergo_format_region("old")
2768 ergo_format_ms("predicted pause time")
2769 ergo_format_ms("target pause time"),
2770 eden_region_length, survivor_region_length,
2771 old_cset_region_length(),
2772 predicted_pause_time_ms, target_pause_time_ms);
2774 double non_young_end_time_sec = os::elapsedTime();
2775 _recorded_non_young_cset_choice_time_ms =
2776 (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2777 }