1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc/g1/concurrentG1Refine.hpp" 27 #include "gc/g1/concurrentMark.hpp" 28 #include "gc/g1/concurrentMarkThread.inline.hpp" 29 #include "gc/g1/g1CollectedHeap.inline.hpp" 30 #include "gc/g1/g1CollectorPolicy.hpp" 31 #include "gc/g1/g1ErgoVerbose.hpp" 32 #include "gc/g1/g1GCPhaseTimes.hpp" 33 #include "gc/g1/g1Log.hpp" 34 #include "gc/g1/heapRegion.inline.hpp" 35 #include "gc/g1/heapRegionRemSet.hpp" 36 #include "gc/shared/gcPolicyCounters.hpp" 37 #include "runtime/arguments.hpp" 38 #include "runtime/java.hpp" 39 #include "runtime/mutexLocker.hpp" 40 #include "utilities/debug.hpp" 41 42 // Different defaults for different number of GC threads 43 // They were chosen by running GCOld and SPECjbb on debris with different 44 // numbers of GC threads and choosing them based on the results 45 46 // all the same 47 static double rs_length_diff_defaults[] = { 48 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 49 }; 50 51 static double cost_per_card_ms_defaults[] = { 52 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015 53 }; 54 55 // all the same 56 static double young_cards_per_entry_ratio_defaults[] = { 57 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 58 }; 59 60 static double cost_per_entry_ms_defaults[] = { 61 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005 62 }; 63 64 static double cost_per_byte_ms_defaults[] = { 65 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009 66 }; 67 68 // these should be pretty consistent 69 static double constant_other_time_ms_defaults[] = { 70 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 71 }; 72 73 74 static double young_other_cost_per_region_ms_defaults[] = { 75 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1 76 }; 77 78 static double non_young_other_cost_per_region_ms_defaults[] = { 79 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30 80 }; 81 82 G1CollectorPolicy::G1CollectorPolicy() : 83 _predictor(G1ConfidencePercent / 100.0), 84 _parallel_gc_threads(ParallelGCThreads), 85 86 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 87 _stop_world_start(0.0), 88 89 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 90 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 91 92 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 93 _prev_collection_pause_end_ms(0.0), 94 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)), 95 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 96 _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)), 97 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)), 98 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)), 99 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 100 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 101 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 102 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)), 103 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 104 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 105 _non_young_other_cost_per_region_ms_seq( 106 new TruncatedSeq(TruncatedSeqLength)), 107 108 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)), 109 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)), 110 111 _pause_time_target_ms((double) MaxGCPauseMillis), 112 113 _recent_prev_end_times_for_all_gcs_sec( 114 new TruncatedSeq(NumPrevPausesForHeuristics)), 115 116 _recent_avg_pause_time_ratio(0.0), 117 _rs_lengths_prediction(0), 118 _max_survivor_regions(0), 119 120 _eden_used_bytes_before_gc(0), 121 _survivor_used_bytes_before_gc(0), 122 _heap_used_bytes_before_gc(0), 123 _metaspace_used_bytes_before_gc(0), 124 _eden_capacity_bytes_before_gc(0), 125 _heap_capacity_bytes_before_gc(0), 126 127 _eden_cset_region_length(0), 128 _survivor_cset_region_length(0), 129 _old_cset_region_length(0), 130 131 _collection_set(NULL), 132 _collection_set_bytes_used_before(0), 133 134 // Incremental CSet attributes 135 _inc_cset_build_state(Inactive), 136 _inc_cset_head(NULL), 137 _inc_cset_tail(NULL), 138 _inc_cset_bytes_used_before(0), 139 _inc_cset_max_finger(NULL), 140 _inc_cset_recorded_rs_lengths(0), 141 _inc_cset_recorded_rs_lengths_diffs(0), 142 _inc_cset_predicted_elapsed_time_ms(0.0), 143 _inc_cset_predicted_elapsed_time_ms_diffs(0.0), 144 145 // add here any more surv rate groups 146 _recorded_survivor_regions(0), 147 _recorded_survivor_head(NULL), 148 _recorded_survivor_tail(NULL), 149 _survivors_age_table(true), 150 151 _gc_overhead_perc(0.0) { 152 153 // SurvRateGroups below must be initialized after the predictor because they 154 // indirectly use it through this object passed to their constructor. 155 _short_lived_surv_rate_group = 156 new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary); 157 _survivor_surv_rate_group = 158 new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary); 159 160 // Set up the region size and associated fields. Given that the 161 // policy is created before the heap, we have to set this up here, 162 // so it's done as soon as possible. 163 164 // It would have been natural to pass initial_heap_byte_size() and 165 // max_heap_byte_size() to setup_heap_region_size() but those have 166 // not been set up at this point since they should be aligned with 167 // the region size. So, there is a circular dependency here. We base 168 // the region size on the heap size, but the heap size should be 169 // aligned with the region size. To get around this we use the 170 // unaligned values for the heap. 171 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize); 172 HeapRegionRemSet::setup_remset_size(); 173 174 G1ErgoVerbose::initialize(); 175 if (PrintAdaptiveSizePolicy) { 176 // Currently, we only use a single switch for all the heuristics. 177 G1ErgoVerbose::set_enabled(true); 178 // Given that we don't currently have a verboseness level 179 // parameter, we'll hardcode this to high. This can be easily 180 // changed in the future. 181 G1ErgoVerbose::set_level(ErgoHigh); 182 } else { 183 G1ErgoVerbose::set_enabled(false); 184 } 185 186 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime()); 187 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0; 188 189 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads); 190 191 int index = MIN2(_parallel_gc_threads - 1, 7); 192 193 _rs_length_diff_seq->add(rs_length_diff_defaults[index]); 194 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]); 195 _cost_scan_hcc_seq->add(0.0); 196 _young_cards_per_entry_ratio_seq->add( 197 young_cards_per_entry_ratio_defaults[index]); 198 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]); 199 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]); 200 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]); 201 _young_other_cost_per_region_ms_seq->add( 202 young_other_cost_per_region_ms_defaults[index]); 203 _non_young_other_cost_per_region_ms_seq->add( 204 non_young_other_cost_per_region_ms_defaults[index]); 205 206 // Below, we might need to calculate the pause time target based on 207 // the pause interval. When we do so we are going to give G1 maximum 208 // flexibility and allow it to do pauses when it needs to. So, we'll 209 // arrange that the pause interval to be pause time target + 1 to 210 // ensure that a) the pause time target is maximized with respect to 211 // the pause interval and b) we maintain the invariant that pause 212 // time target < pause interval. If the user does not want this 213 // maximum flexibility, they will have to set the pause interval 214 // explicitly. 215 216 // First make sure that, if either parameter is set, its value is 217 // reasonable. 218 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 219 if (MaxGCPauseMillis < 1) { 220 vm_exit_during_initialization("MaxGCPauseMillis should be " 221 "greater than 0"); 222 } 223 } 224 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 225 if (GCPauseIntervalMillis < 1) { 226 vm_exit_during_initialization("GCPauseIntervalMillis should be " 227 "greater than 0"); 228 } 229 } 230 231 // Then, if the pause time target parameter was not set, set it to 232 // the default value. 233 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 234 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 235 // The default pause time target in G1 is 200ms 236 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200); 237 } else { 238 // We do not allow the pause interval to be set without the 239 // pause time target 240 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set " 241 "without setting MaxGCPauseMillis"); 242 } 243 } 244 245 // Then, if the interval parameter was not set, set it according to 246 // the pause time target (this will also deal with the case when the 247 // pause time target is the default value). 248 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 249 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1); 250 } 251 252 // Finally, make sure that the two parameters are consistent. 253 if (MaxGCPauseMillis >= GCPauseIntervalMillis) { 254 char buffer[256]; 255 jio_snprintf(buffer, 256, 256 "MaxGCPauseMillis (%u) should be less than " 257 "GCPauseIntervalMillis (%u)", 258 MaxGCPauseMillis, GCPauseIntervalMillis); 259 vm_exit_during_initialization(buffer); 260 } 261 262 double max_gc_time = (double) MaxGCPauseMillis / 1000.0; 263 double time_slice = (double) GCPauseIntervalMillis / 1000.0; 264 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time); 265 266 // start conservatively (around 50ms is about right) 267 _concurrent_mark_remark_times_ms->add(0.05); 268 _concurrent_mark_cleanup_times_ms->add(0.20); 269 _tenuring_threshold = MaxTenuringThreshold; 270 271 assert(GCTimeRatio > 0, 272 "we should have set it to a default value set_g1_gc_flags() " 273 "if a user set it to 0"); 274 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio)); 275 276 uintx reserve_perc = G1ReservePercent; 277 // Put an artificial ceiling on this so that it's not set to a silly value. 278 if (reserve_perc > 50) { 279 reserve_perc = 50; 280 warning("G1ReservePercent is set to a value that is too large, " 281 "it's been updated to " UINTX_FORMAT, reserve_perc); 282 } 283 _reserve_factor = (double) reserve_perc / 100.0; 284 // This will be set when the heap is expanded 285 // for the first time during initialization. 286 _reserve_regions = 0; 287 288 _collectionSetChooser = new CollectionSetChooser(); 289 } 290 291 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const { 292 return _predictor.get_new_prediction(seq); 293 } 294 295 void G1CollectorPolicy::initialize_alignments() { 296 _space_alignment = HeapRegion::GrainBytes; 297 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint(); 298 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 299 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size); 300 } 301 302 void G1CollectorPolicy::initialize_flags() { 303 if (G1HeapRegionSize != HeapRegion::GrainBytes) { 304 FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes); 305 } 306 307 if (SurvivorRatio < 1) { 308 vm_exit_during_initialization("Invalid survivor ratio specified"); 309 } 310 CollectorPolicy::initialize_flags(); 311 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags 312 } 313 314 void G1CollectorPolicy::post_heap_initialize() { 315 uintx max_regions = G1CollectedHeap::heap()->max_regions(); 316 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes; 317 if (max_young_size != MaxNewSize) { 318 FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size); 319 } 320 } 321 322 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); } 323 324 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true), 325 _min_desired_young_length(0), _max_desired_young_length(0) { 326 if (FLAG_IS_CMDLINE(NewRatio)) { 327 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) { 328 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio"); 329 } else { 330 _sizer_kind = SizerNewRatio; 331 _adaptive_size = false; 332 return; 333 } 334 } 335 336 if (NewSize > MaxNewSize) { 337 if (FLAG_IS_CMDLINE(MaxNewSize)) { 338 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). " 339 "A new max generation size of " SIZE_FORMAT "k will be used.", 340 NewSize/K, MaxNewSize/K, NewSize/K); 341 } 342 MaxNewSize = NewSize; 343 } 344 345 if (FLAG_IS_CMDLINE(NewSize)) { 346 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes), 347 1U); 348 if (FLAG_IS_CMDLINE(MaxNewSize)) { 349 _max_desired_young_length = 350 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 351 1U); 352 _sizer_kind = SizerMaxAndNewSize; 353 _adaptive_size = _min_desired_young_length == _max_desired_young_length; 354 } else { 355 _sizer_kind = SizerNewSizeOnly; 356 } 357 } else if (FLAG_IS_CMDLINE(MaxNewSize)) { 358 _max_desired_young_length = 359 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 360 1U); 361 _sizer_kind = SizerMaxNewSizeOnly; 362 } 363 } 364 365 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) { 366 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100; 367 return MAX2(1U, default_value); 368 } 369 370 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) { 371 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100; 372 return MAX2(1U, default_value); 373 } 374 375 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) { 376 assert(number_of_heap_regions > 0, "Heap must be initialized"); 377 378 switch (_sizer_kind) { 379 case SizerDefaults: 380 *min_young_length = calculate_default_min_length(number_of_heap_regions); 381 *max_young_length = calculate_default_max_length(number_of_heap_regions); 382 break; 383 case SizerNewSizeOnly: 384 *max_young_length = calculate_default_max_length(number_of_heap_regions); 385 *max_young_length = MAX2(*min_young_length, *max_young_length); 386 break; 387 case SizerMaxNewSizeOnly: 388 *min_young_length = calculate_default_min_length(number_of_heap_regions); 389 *min_young_length = MIN2(*min_young_length, *max_young_length); 390 break; 391 case SizerMaxAndNewSize: 392 // Do nothing. Values set on the command line, don't update them at runtime. 393 break; 394 case SizerNewRatio: 395 *min_young_length = number_of_heap_regions / (NewRatio + 1); 396 *max_young_length = *min_young_length; 397 break; 398 default: 399 ShouldNotReachHere(); 400 } 401 402 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values"); 403 } 404 405 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) { 406 // We need to pass the desired values because recalculation may not update these 407 // values in some cases. 408 uint temp = _min_desired_young_length; 409 uint result = _max_desired_young_length; 410 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result); 411 return result; 412 } 413 414 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) { 415 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length, 416 &_max_desired_young_length); 417 } 418 419 void G1CollectorPolicy::init() { 420 // Set aside an initial future to_space. 421 _g1 = G1CollectedHeap::heap(); 422 423 assert(Heap_lock->owned_by_self(), "Locking discipline."); 424 425 initialize_gc_policy_counters(); 426 427 if (adaptive_young_list_length()) { 428 _young_list_fixed_length = 0; 429 } else { 430 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length(); 431 } 432 _free_regions_at_end_of_collection = _g1->num_free_regions(); 433 434 update_young_list_max_and_target_length(); 435 // We may immediately start allocating regions and placing them on the 436 // collection set list. Initialize the per-collection set info 437 start_incremental_cset_building(); 438 } 439 440 void G1CollectorPolicy::note_gc_start(uint num_active_workers) { 441 phase_times()->note_gc_start(num_active_workers); 442 } 443 444 // Create the jstat counters for the policy. 445 void G1CollectorPolicy::initialize_gc_policy_counters() { 446 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3); 447 } 448 449 bool G1CollectorPolicy::predict_will_fit(uint young_length, 450 double base_time_ms, 451 uint base_free_regions, 452 double target_pause_time_ms) const { 453 if (young_length >= base_free_regions) { 454 // end condition 1: not enough space for the young regions 455 return false; 456 } 457 458 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1); 459 size_t bytes_to_copy = 460 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); 461 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy); 462 double young_other_time_ms = predict_young_other_time_ms(young_length); 463 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms; 464 if (pause_time_ms > target_pause_time_ms) { 465 // end condition 2: prediction is over the target pause time 466 return false; 467 } 468 469 size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes; 470 if ((2.0 /* magic */ * _predictor.sigma()) * bytes_to_copy > free_bytes) { 471 // end condition 3: out-of-space (conservatively!) 472 return false; 473 } 474 475 // success! 476 return true; 477 } 478 479 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) { 480 // re-calculate the necessary reserve 481 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; 482 // We use ceiling so that if reserve_regions_d is > 0.0 (but 483 // smaller than 1.0) we'll get 1. 484 _reserve_regions = (uint) ceil(reserve_regions_d); 485 486 _young_gen_sizer->heap_size_changed(new_number_of_regions); 487 } 488 489 uint G1CollectorPolicy::calculate_young_list_desired_min_length( 490 uint base_min_length) const { 491 uint desired_min_length = 0; 492 if (adaptive_young_list_length()) { 493 if (_alloc_rate_ms_seq->num() > 3) { 494 double now_sec = os::elapsedTime(); 495 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; 496 double alloc_rate_ms = predict_alloc_rate_ms(); 497 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); 498 } else { 499 // otherwise we don't have enough info to make the prediction 500 } 501 } 502 desired_min_length += base_min_length; 503 // make sure we don't go below any user-defined minimum bound 504 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length); 505 } 506 507 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const { 508 // Here, we might want to also take into account any additional 509 // constraints (i.e., user-defined minimum bound). Currently, we 510 // effectively don't set this bound. 511 return _young_gen_sizer->max_desired_young_length(); 512 } 513 514 void G1CollectorPolicy::update_young_list_max_and_target_length() { 515 update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq)); 516 } 517 518 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) { 519 update_young_list_target_length(rs_lengths); 520 update_max_gc_locker_expansion(); 521 } 522 523 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) { 524 _young_list_target_length = bounded_young_list_target_length(rs_lengths); 525 } 526 527 void G1CollectorPolicy::update_young_list_target_length() { 528 update_young_list_target_length(get_new_prediction(_rs_lengths_seq)); 529 } 530 531 uint G1CollectorPolicy::bounded_young_list_target_length(size_t rs_lengths) const { 532 // Calculate the absolute and desired min bounds. 533 534 // This is how many young regions we already have (currently: the survivors). 535 uint base_min_length = recorded_survivor_regions(); 536 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length); 537 // This is the absolute minimum young length. Ensure that we 538 // will at least have one eden region available for allocation. 539 uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1); 540 // If we shrank the young list target it should not shrink below the current size. 541 desired_min_length = MAX2(desired_min_length, absolute_min_length); 542 // Calculate the absolute and desired max bounds. 543 544 // We will try our best not to "eat" into the reserve. 545 uint absolute_max_length = 0; 546 if (_free_regions_at_end_of_collection > _reserve_regions) { 547 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; 548 } 549 uint desired_max_length = calculate_young_list_desired_max_length(); 550 if (desired_max_length > absolute_max_length) { 551 desired_max_length = absolute_max_length; 552 } 553 554 uint young_list_target_length = 0; 555 if (adaptive_young_list_length()) { 556 if (collector_state()->gcs_are_young()) { 557 young_list_target_length = 558 calculate_young_list_target_length(rs_lengths, 559 base_min_length, 560 desired_min_length, 561 desired_max_length); 562 } else { 563 // Don't calculate anything and let the code below bound it to 564 // the desired_min_length, i.e., do the next GC as soon as 565 // possible to maximize how many old regions we can add to it. 566 } 567 } else { 568 // The user asked for a fixed young gen so we'll fix the young gen 569 // whether the next GC is young or mixed. 570 young_list_target_length = _young_list_fixed_length; 571 } 572 573 // Make sure we don't go over the desired max length, nor under the 574 // desired min length. In case they clash, desired_min_length wins 575 // which is why that test is second. 576 if (young_list_target_length > desired_max_length) { 577 young_list_target_length = desired_max_length; 578 } 579 if (young_list_target_length < desired_min_length) { 580 young_list_target_length = desired_min_length; 581 } 582 583 assert(young_list_target_length > recorded_survivor_regions(), 584 "we should be able to allocate at least one eden region"); 585 assert(young_list_target_length >= absolute_min_length, "post-condition"); 586 587 return young_list_target_length; 588 } 589 590 uint 591 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths, 592 uint base_min_length, 593 uint desired_min_length, 594 uint desired_max_length) const { 595 assert(adaptive_young_list_length(), "pre-condition"); 596 assert(collector_state()->gcs_are_young(), "only call this for young GCs"); 597 598 // In case some edge-condition makes the desired max length too small... 599 if (desired_max_length <= desired_min_length) { 600 return desired_min_length; 601 } 602 603 // We'll adjust min_young_length and max_young_length not to include 604 // the already allocated young regions (i.e., so they reflect the 605 // min and max eden regions we'll allocate). The base_min_length 606 // will be reflected in the predictions by the 607 // survivor_regions_evac_time prediction. 608 assert(desired_min_length > base_min_length, "invariant"); 609 uint min_young_length = desired_min_length - base_min_length; 610 assert(desired_max_length > base_min_length, "invariant"); 611 uint max_young_length = desired_max_length - base_min_length; 612 613 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; 614 double survivor_regions_evac_time = predict_survivor_regions_evac_time(); 615 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq); 616 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff(); 617 size_t scanned_cards = predict_young_card_num(adj_rs_lengths); 618 double base_time_ms = 619 predict_base_elapsed_time_ms(pending_cards, scanned_cards) + 620 survivor_regions_evac_time; 621 uint available_free_regions = _free_regions_at_end_of_collection; 622 uint base_free_regions = 0; 623 if (available_free_regions > _reserve_regions) { 624 base_free_regions = available_free_regions - _reserve_regions; 625 } 626 627 // Here, we will make sure that the shortest young length that 628 // makes sense fits within the target pause time. 629 630 if (predict_will_fit(min_young_length, base_time_ms, 631 base_free_regions, target_pause_time_ms)) { 632 // The shortest young length will fit into the target pause time; 633 // we'll now check whether the absolute maximum number of young 634 // regions will fit in the target pause time. If not, we'll do 635 // a binary search between min_young_length and max_young_length. 636 if (predict_will_fit(max_young_length, base_time_ms, 637 base_free_regions, target_pause_time_ms)) { 638 // The maximum young length will fit into the target pause time. 639 // We are done so set min young length to the maximum length (as 640 // the result is assumed to be returned in min_young_length). 641 min_young_length = max_young_length; 642 } else { 643 // The maximum possible number of young regions will not fit within 644 // the target pause time so we'll search for the optimal 645 // length. The loop invariants are: 646 // 647 // min_young_length < max_young_length 648 // min_young_length is known to fit into the target pause time 649 // max_young_length is known not to fit into the target pause time 650 // 651 // Going into the loop we know the above hold as we've just 652 // checked them. Every time around the loop we check whether 653 // the middle value between min_young_length and 654 // max_young_length fits into the target pause time. If it 655 // does, it becomes the new min. If it doesn't, it becomes 656 // the new max. This way we maintain the loop invariants. 657 658 assert(min_young_length < max_young_length, "invariant"); 659 uint diff = (max_young_length - min_young_length) / 2; 660 while (diff > 0) { 661 uint young_length = min_young_length + diff; 662 if (predict_will_fit(young_length, base_time_ms, 663 base_free_regions, target_pause_time_ms)) { 664 min_young_length = young_length; 665 } else { 666 max_young_length = young_length; 667 } 668 assert(min_young_length < max_young_length, "invariant"); 669 diff = (max_young_length - min_young_length) / 2; 670 } 671 // The results is min_young_length which, according to the 672 // loop invariants, should fit within the target pause time. 673 674 // These are the post-conditions of the binary search above: 675 assert(min_young_length < max_young_length, 676 "otherwise we should have discovered that max_young_length " 677 "fits into the pause target and not done the binary search"); 678 assert(predict_will_fit(min_young_length, base_time_ms, 679 base_free_regions, target_pause_time_ms), 680 "min_young_length, the result of the binary search, should " 681 "fit into the pause target"); 682 assert(!predict_will_fit(min_young_length + 1, base_time_ms, 683 base_free_regions, target_pause_time_ms), 684 "min_young_length, the result of the binary search, should be " 685 "optimal, so no larger length should fit into the pause target"); 686 } 687 } else { 688 // Even the minimum length doesn't fit into the pause time 689 // target, return it as the result nevertheless. 690 } 691 return base_min_length + min_young_length; 692 } 693 694 double G1CollectorPolicy::predict_survivor_regions_evac_time() const { 695 double survivor_regions_evac_time = 0.0; 696 for (HeapRegion * r = _recorded_survivor_head; 697 r != NULL && r != _recorded_survivor_tail->get_next_young_region(); 698 r = r->get_next_young_region()) { 699 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young()); 700 } 701 return survivor_regions_evac_time; 702 } 703 704 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() { 705 guarantee( adaptive_young_list_length(), "should not call this otherwise" ); 706 707 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths(); 708 if (rs_lengths > _rs_lengths_prediction) { 709 // add 10% to avoid having to recalculate often 710 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; 711 update_rs_lengths_prediction(rs_lengths_prediction); 712 713 update_young_list_max_and_target_length(rs_lengths_prediction); 714 } 715 } 716 717 void G1CollectorPolicy::update_rs_lengths_prediction() { 718 update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq)); 719 } 720 721 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) { 722 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) { 723 _rs_lengths_prediction = prediction; 724 } 725 } 726 727 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size, 728 bool is_tlab, 729 bool* gc_overhead_limit_was_exceeded) { 730 guarantee(false, "Not using this policy feature yet."); 731 return NULL; 732 } 733 734 // This method controls how a collector handles one or more 735 // of its generations being fully allocated. 736 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size, 737 bool is_tlab) { 738 guarantee(false, "Not using this policy feature yet."); 739 return NULL; 740 } 741 742 743 #ifndef PRODUCT 744 bool G1CollectorPolicy::verify_young_ages() { 745 HeapRegion* head = _g1->young_list()->first_region(); 746 return 747 verify_young_ages(head, _short_lived_surv_rate_group); 748 // also call verify_young_ages on any additional surv rate groups 749 } 750 751 bool 752 G1CollectorPolicy::verify_young_ages(HeapRegion* head, 753 SurvRateGroup *surv_rate_group) { 754 guarantee( surv_rate_group != NULL, "pre-condition" ); 755 756 const char* name = surv_rate_group->name(); 757 bool ret = true; 758 int prev_age = -1; 759 760 for (HeapRegion* curr = head; 761 curr != NULL; 762 curr = curr->get_next_young_region()) { 763 SurvRateGroup* group = curr->surv_rate_group(); 764 if (group == NULL && !curr->is_survivor()) { 765 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name); 766 ret = false; 767 } 768 769 if (surv_rate_group == group) { 770 int age = curr->age_in_surv_rate_group(); 771 772 if (age < 0) { 773 gclog_or_tty->print_cr("## %s: encountered negative age", name); 774 ret = false; 775 } 776 777 if (age <= prev_age) { 778 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing " 779 "(%d, %d)", name, age, prev_age); 780 ret = false; 781 } 782 prev_age = age; 783 } 784 } 785 786 return ret; 787 } 788 #endif // PRODUCT 789 790 void G1CollectorPolicy::record_full_collection_start() { 791 _full_collection_start_sec = os::elapsedTime(); 792 record_heap_size_info_at_start(true /* full */); 793 // Release the future to-space so that it is available for compaction into. 794 collector_state()->set_full_collection(true); 795 } 796 797 void G1CollectorPolicy::record_full_collection_end() { 798 // Consider this like a collection pause for the purposes of allocation 799 // since last pause. 800 double end_sec = os::elapsedTime(); 801 double full_gc_time_sec = end_sec - _full_collection_start_sec; 802 double full_gc_time_ms = full_gc_time_sec * 1000.0; 803 804 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms); 805 806 update_recent_gc_times(end_sec, full_gc_time_ms); 807 808 collector_state()->set_full_collection(false); 809 810 // "Nuke" the heuristics that control the young/mixed GC 811 // transitions and make sure we start with young GCs after the Full GC. 812 collector_state()->set_gcs_are_young(true); 813 collector_state()->set_last_young_gc(false); 814 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0)); 815 collector_state()->set_during_initial_mark_pause(false); 816 collector_state()->set_in_marking_window(false); 817 collector_state()->set_in_marking_window_im(false); 818 819 _short_lived_surv_rate_group->start_adding_regions(); 820 // also call this on any additional surv rate groups 821 822 record_survivor_regions(0, NULL, NULL); 823 824 _free_regions_at_end_of_collection = _g1->num_free_regions(); 825 // Reset survivors SurvRateGroup. 826 _survivor_surv_rate_group->reset(); 827 update_young_list_max_and_target_length(); 828 update_rs_lengths_prediction(); 829 _collectionSetChooser->clear(); 830 } 831 832 void G1CollectorPolicy::record_stop_world_start() { 833 _stop_world_start = os::elapsedTime(); 834 } 835 836 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) { 837 // We only need to do this here as the policy will only be applied 838 // to the GC we're about to start. so, no point is calculating this 839 // every time we calculate / recalculate the target young length. 840 update_survivors_policy(); 841 842 assert(_g1->used() == _g1->recalculate_used(), 843 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT, 844 _g1->used(), _g1->recalculate_used()); 845 846 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0; 847 _trace_young_gen_time_data.record_start_collection(s_w_t_ms); 848 _stop_world_start = 0.0; 849 850 record_heap_size_info_at_start(false /* full */); 851 852 phase_times()->record_cur_collection_start_sec(start_time_sec); 853 _pending_cards = _g1->pending_card_num(); 854 855 _collection_set_bytes_used_before = 0; 856 _bytes_copied_during_gc = 0; 857 858 collector_state()->set_last_gc_was_young(false); 859 860 // do that for any other surv rate groups 861 _short_lived_surv_rate_group->stop_adding_regions(); 862 _survivors_age_table.clear(); 863 864 assert( verify_young_ages(), "region age verification" ); 865 } 866 867 void G1CollectorPolicy::record_concurrent_mark_init_end(double 868 mark_init_elapsed_time_ms) { 869 collector_state()->set_during_marking(true); 870 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now"); 871 collector_state()->set_during_initial_mark_pause(false); 872 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms; 873 } 874 875 void G1CollectorPolicy::record_concurrent_mark_remark_start() { 876 _mark_remark_start_sec = os::elapsedTime(); 877 collector_state()->set_during_marking(false); 878 } 879 880 void G1CollectorPolicy::record_concurrent_mark_remark_end() { 881 double end_time_sec = os::elapsedTime(); 882 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; 883 _concurrent_mark_remark_times_ms->add(elapsed_time_ms); 884 _cur_mark_stop_world_time_ms += elapsed_time_ms; 885 _prev_collection_pause_end_ms += elapsed_time_ms; 886 887 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec); 888 } 889 890 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() { 891 _mark_cleanup_start_sec = os::elapsedTime(); 892 } 893 894 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() { 895 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc", 896 "skip last young-only gc"); 897 collector_state()->set_last_young_gc(should_continue_with_reclaim); 898 collector_state()->set_in_marking_window(false); 899 } 900 901 void G1CollectorPolicy::record_concurrent_pause() { 902 if (_stop_world_start > 0.0) { 903 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0; 904 _trace_young_gen_time_data.record_yield_time(yield_ms); 905 } 906 } 907 908 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const { 909 return phase_times()->average_time_ms(phase); 910 } 911 912 double G1CollectorPolicy::young_other_time_ms() const { 913 return phase_times()->young_cset_choice_time_ms() + 914 phase_times()->young_free_cset_time_ms(); 915 } 916 917 double G1CollectorPolicy::non_young_other_time_ms() const { 918 return phase_times()->non_young_cset_choice_time_ms() + 919 phase_times()->non_young_free_cset_time_ms(); 920 921 } 922 923 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const { 924 return pause_time_ms - 925 average_time_ms(G1GCPhaseTimes::UpdateRS) - 926 average_time_ms(G1GCPhaseTimes::ScanRS) - 927 average_time_ms(G1GCPhaseTimes::ObjCopy) - 928 average_time_ms(G1GCPhaseTimes::Termination); 929 } 930 931 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const { 932 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms(); 933 } 934 935 bool G1CollectorPolicy::about_to_start_mixed_phase() const { 936 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc(); 937 } 938 939 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { 940 if (about_to_start_mixed_phase()) { 941 return false; 942 } 943 944 size_t marking_initiating_used_threshold = 945 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent; 946 size_t cur_used_bytes = _g1->non_young_capacity_bytes(); 947 size_t alloc_byte_size = alloc_word_size * HeapWordSize; 948 949 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) { 950 if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) { 951 ergo_verbose5(ErgoConcCycles, 952 "request concurrent cycle initiation", 953 ergo_format_reason("occupancy higher than threshold") 954 ergo_format_byte("occupancy") 955 ergo_format_byte("allocation request") 956 ergo_format_byte_perc("threshold") 957 ergo_format_str("source"), 958 cur_used_bytes, 959 alloc_byte_size, 960 marking_initiating_used_threshold, 961 (double) InitiatingHeapOccupancyPercent, 962 source); 963 return true; 964 } else { 965 ergo_verbose5(ErgoConcCycles, 966 "do not request concurrent cycle initiation", 967 ergo_format_reason("still doing mixed collections") 968 ergo_format_byte("occupancy") 969 ergo_format_byte("allocation request") 970 ergo_format_byte_perc("threshold") 971 ergo_format_str("source"), 972 cur_used_bytes, 973 alloc_byte_size, 974 marking_initiating_used_threshold, 975 (double) InitiatingHeapOccupancyPercent, 976 source); 977 } 978 } 979 980 return false; 981 } 982 983 // Anything below that is considered to be zero 984 #define MIN_TIMER_GRANULARITY 0.0000001 985 986 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) { 987 double end_time_sec = os::elapsedTime(); 988 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(), 989 "otherwise, the subtraction below does not make sense"); 990 size_t rs_size = 991 _cur_collection_pause_used_regions_at_start - cset_region_length(); 992 size_t cur_used_bytes = _g1->used(); 993 assert(cur_used_bytes == _g1->recalculate_used(), "It should!"); 994 bool last_pause_included_initial_mark = false; 995 bool update_stats = !_g1->evacuation_failed(); 996 997 #ifndef PRODUCT 998 if (G1YoungSurvRateVerbose) { 999 gclog_or_tty->cr(); 1000 _short_lived_surv_rate_group->print(); 1001 // do that for any other surv rate groups too 1002 } 1003 #endif // PRODUCT 1004 1005 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause(); 1006 if (last_pause_included_initial_mark) { 1007 record_concurrent_mark_init_end(0.0); 1008 } else { 1009 maybe_start_marking(); 1010 } 1011 1012 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0, end_time_sec); 1013 1014 if (update_stats) { 1015 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times()); 1016 // this is where we update the allocation rate of the application 1017 double app_time_ms = 1018 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms); 1019 if (app_time_ms < MIN_TIMER_GRANULARITY) { 1020 // This usually happens due to the timer not having the required 1021 // granularity. Some Linuxes are the usual culprits. 1022 // We'll just set it to something (arbitrarily) small. 1023 app_time_ms = 1.0; 1024 } 1025 // We maintain the invariant that all objects allocated by mutator 1026 // threads will be allocated out of eden regions. So, we can use 1027 // the eden region number allocated since the previous GC to 1028 // calculate the application's allocate rate. The only exception 1029 // to that is humongous objects that are allocated separately. But 1030 // given that humongous object allocations do not really affect 1031 // either the pause's duration nor when the next pause will take 1032 // place we can safely ignore them here. 1033 uint regions_allocated = eden_cset_region_length(); 1034 double alloc_rate_ms = (double) regions_allocated / app_time_ms; 1035 _alloc_rate_ms_seq->add(alloc_rate_ms); 1036 1037 double interval_ms = 1038 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0; 1039 update_recent_gc_times(end_time_sec, pause_time_ms); 1040 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms; 1041 if (recent_avg_pause_time_ratio() < 0.0 || 1042 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) { 1043 #ifndef PRODUCT 1044 // Dump info to allow post-facto debugging 1045 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds"); 1046 gclog_or_tty->print_cr("-------------------------------------------"); 1047 gclog_or_tty->print_cr("Recent GC Times (ms):"); 1048 _recent_gc_times_ms->dump(); 1049 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec); 1050 _recent_prev_end_times_for_all_gcs_sec->dump(); 1051 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f", 1052 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio()); 1053 // In debug mode, terminate the JVM if the user wants to debug at this point. 1054 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above"); 1055 #endif // !PRODUCT 1056 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in 1057 // CR 6902692 by redoing the manner in which the ratio is incrementally computed. 1058 if (_recent_avg_pause_time_ratio < 0.0) { 1059 _recent_avg_pause_time_ratio = 0.0; 1060 } else { 1061 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant"); 1062 _recent_avg_pause_time_ratio = 1.0; 1063 } 1064 } 1065 } 1066 1067 bool new_in_marking_window = collector_state()->in_marking_window(); 1068 bool new_in_marking_window_im = false; 1069 if (last_pause_included_initial_mark) { 1070 new_in_marking_window = true; 1071 new_in_marking_window_im = true; 1072 } 1073 1074 if (collector_state()->last_young_gc()) { 1075 // This is supposed to to be the "last young GC" before we start 1076 // doing mixed GCs. Here we decide whether to start mixed GCs or not. 1077 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC"); 1078 1079 if (next_gc_should_be_mixed("start mixed GCs", 1080 "do not start mixed GCs")) { 1081 collector_state()->set_gcs_are_young(false); 1082 } 1083 1084 collector_state()->set_last_young_gc(false); 1085 } 1086 1087 if (!collector_state()->last_gc_was_young()) { 1088 // This is a mixed GC. Here we decide whether to continue doing 1089 // mixed GCs or not. 1090 1091 if (!next_gc_should_be_mixed("continue mixed GCs", 1092 "do not continue mixed GCs")) { 1093 collector_state()->set_gcs_are_young(true); 1094 1095 maybe_start_marking(); 1096 } 1097 } 1098 1099 _short_lived_surv_rate_group->start_adding_regions(); 1100 // Do that for any other surv rate groups 1101 1102 if (update_stats) { 1103 double cost_per_card_ms = 0.0; 1104 double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC); 1105 if (_pending_cards > 0) { 1106 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards; 1107 _cost_per_card_ms_seq->add(cost_per_card_ms); 1108 } 1109 _cost_scan_hcc_seq->add(cost_scan_hcc); 1110 1111 double cost_per_entry_ms = 0.0; 1112 if (cards_scanned > 10) { 1113 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned; 1114 if (collector_state()->last_gc_was_young()) { 1115 _cost_per_entry_ms_seq->add(cost_per_entry_ms); 1116 } else { 1117 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms); 1118 } 1119 } 1120 1121 if (_max_rs_lengths > 0) { 1122 double cards_per_entry_ratio = 1123 (double) cards_scanned / (double) _max_rs_lengths; 1124 if (collector_state()->last_gc_was_young()) { 1125 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1126 } else { 1127 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1128 } 1129 } 1130 1131 // This is defensive. For a while _max_rs_lengths could get 1132 // smaller than _recorded_rs_lengths which was causing 1133 // rs_length_diff to get very large and mess up the RSet length 1134 // predictions. The reason was unsafe concurrent updates to the 1135 // _inc_cset_recorded_rs_lengths field which the code below guards 1136 // against (see CR 7118202). This bug has now been fixed (see CR 1137 // 7119027). However, I'm still worried that 1138 // _inc_cset_recorded_rs_lengths might still end up somewhat 1139 // inaccurate. The concurrent refinement thread calculates an 1140 // RSet's length concurrently with other CR threads updating it 1141 // which might cause it to calculate the length incorrectly (if, 1142 // say, it's in mid-coarsening). So I'll leave in the defensive 1143 // conditional below just in case. 1144 size_t rs_length_diff = 0; 1145 if (_max_rs_lengths > _recorded_rs_lengths) { 1146 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths; 1147 } 1148 _rs_length_diff_seq->add((double) rs_length_diff); 1149 1150 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes; 1151 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes; 1152 double cost_per_byte_ms = 0.0; 1153 1154 if (copied_bytes > 0) { 1155 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes; 1156 if (collector_state()->in_marking_window()) { 1157 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms); 1158 } else { 1159 _cost_per_byte_ms_seq->add(cost_per_byte_ms); 1160 } 1161 } 1162 1163 if (young_cset_region_length() > 0) { 1164 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() / 1165 young_cset_region_length()); 1166 } 1167 1168 if (old_cset_region_length() > 0) { 1169 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() / 1170 old_cset_region_length()); 1171 } 1172 1173 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms)); 1174 1175 _pending_cards_seq->add((double) _pending_cards); 1176 _rs_lengths_seq->add((double) _max_rs_lengths); 1177 } 1178 1179 collector_state()->set_in_marking_window(new_in_marking_window); 1180 collector_state()->set_in_marking_window_im(new_in_marking_window_im); 1181 _free_regions_at_end_of_collection = _g1->num_free_regions(); 1182 update_young_list_max_and_target_length(); 1183 update_rs_lengths_prediction(); 1184 1185 // Note that _mmu_tracker->max_gc_time() returns the time in seconds. 1186 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; 1187 1188 double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC); 1189 1190 if (update_rs_time_goal_ms < scan_hcc_time_ms) { 1191 ergo_verbose2(ErgoTiming, 1192 "adjust concurrent refinement thresholds", 1193 ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal") 1194 ergo_format_ms("Update RS time goal") 1195 ergo_format_ms("Scan HCC time"), 1196 update_rs_time_goal_ms, 1197 scan_hcc_time_ms); 1198 1199 update_rs_time_goal_ms = 0; 1200 } else { 1201 update_rs_time_goal_ms -= scan_hcc_time_ms; 1202 } 1203 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms, 1204 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS), 1205 update_rs_time_goal_ms); 1206 1207 _collectionSetChooser->verify(); 1208 } 1209 1210 #define EXT_SIZE_FORMAT "%.1f%s" 1211 #define EXT_SIZE_PARAMS(bytes) \ 1212 byte_size_in_proper_unit((double)(bytes)), \ 1213 proper_unit_for_byte_size((bytes)) 1214 1215 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) { 1216 YoungList* young_list = _g1->young_list(); 1217 _eden_used_bytes_before_gc = young_list->eden_used_bytes(); 1218 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes(); 1219 _heap_capacity_bytes_before_gc = _g1->capacity(); 1220 _heap_used_bytes_before_gc = _g1->used(); 1221 _cur_collection_pause_used_regions_at_start = _g1->num_used_regions(); 1222 1223 _eden_capacity_bytes_before_gc = 1224 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc; 1225 1226 if (full) { 1227 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes(); 1228 } 1229 } 1230 1231 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const { 1232 size_t bytes_after = _g1->used(); 1233 size_t capacity = _g1->capacity(); 1234 1235 gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)", 1236 byte_size_in_proper_unit(bytes_before), 1237 proper_unit_for_byte_size(bytes_before), 1238 byte_size_in_proper_unit(bytes_after), 1239 proper_unit_for_byte_size(bytes_after), 1240 byte_size_in_proper_unit(capacity), 1241 proper_unit_for_byte_size(capacity)); 1242 } 1243 1244 void G1CollectorPolicy::print_heap_transition() const { 1245 print_heap_transition(_heap_used_bytes_before_gc); 1246 } 1247 1248 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const { 1249 YoungList* young_list = _g1->young_list(); 1250 1251 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes(); 1252 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes(); 1253 size_t heap_used_bytes_after_gc = _g1->used(); 1254 1255 size_t heap_capacity_bytes_after_gc = _g1->capacity(); 1256 size_t eden_capacity_bytes_after_gc = 1257 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc; 1258 1259 gclog_or_tty->print( 1260 " [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") " 1261 "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " " 1262 "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" 1263 EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]", 1264 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc), 1265 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc), 1266 EXT_SIZE_PARAMS(eden_used_bytes_after_gc), 1267 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc), 1268 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc), 1269 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc), 1270 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc), 1271 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc), 1272 EXT_SIZE_PARAMS(heap_used_bytes_after_gc), 1273 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc)); 1274 1275 if (full) { 1276 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc); 1277 } 1278 1279 gclog_or_tty->cr(); 1280 } 1281 1282 void G1CollectorPolicy::print_phases(double pause_time_sec) { 1283 phase_times()->print(pause_time_sec); 1284 } 1285 1286 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time, 1287 double update_rs_processed_buffers, 1288 double goal_ms) { 1289 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1290 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine(); 1291 1292 if (G1UseAdaptiveConcRefinement) { 1293 const int k_gy = 3, k_gr = 6; 1294 const double inc_k = 1.1, dec_k = 0.9; 1295 1296 int g = cg1r->green_zone(); 1297 if (update_rs_time > goal_ms) { 1298 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing. 1299 } else { 1300 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) { 1301 g = (int)MAX2(g * inc_k, g + 1.0); 1302 } 1303 } 1304 // Change the refinement threads params 1305 cg1r->set_green_zone(g); 1306 cg1r->set_yellow_zone(g * k_gy); 1307 cg1r->set_red_zone(g * k_gr); 1308 cg1r->reinitialize_threads(); 1309 1310 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1); 1311 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta, 1312 cg1r->yellow_zone()); 1313 // Change the barrier params 1314 dcqs.set_process_completed_threshold(processing_threshold); 1315 dcqs.set_max_completed_queue(cg1r->red_zone()); 1316 } 1317 1318 int curr_queue_size = dcqs.completed_buffers_num(); 1319 if (curr_queue_size >= cg1r->yellow_zone()) { 1320 dcqs.set_completed_queue_padding(curr_queue_size); 1321 } else { 1322 dcqs.set_completed_queue_padding(0); 1323 } 1324 dcqs.notify_if_necessary(); 1325 } 1326 1327 size_t G1CollectorPolicy::predict_rs_length_diff() const { 1328 return (size_t) get_new_prediction(_rs_length_diff_seq); 1329 } 1330 1331 double G1CollectorPolicy::predict_alloc_rate_ms() const { 1332 return get_new_prediction(_alloc_rate_ms_seq); 1333 } 1334 1335 double G1CollectorPolicy::predict_cost_per_card_ms() const { 1336 return get_new_prediction(_cost_per_card_ms_seq); 1337 } 1338 1339 double G1CollectorPolicy::predict_scan_hcc_ms() const { 1340 return get_new_prediction(_cost_scan_hcc_seq); 1341 } 1342 1343 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const { 1344 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms(); 1345 } 1346 1347 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const { 1348 return get_new_prediction(_young_cards_per_entry_ratio_seq); 1349 } 1350 1351 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const { 1352 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 1353 return predict_young_cards_per_entry_ratio(); 1354 } else { 1355 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 1356 } 1357 } 1358 1359 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const { 1360 return (size_t) (rs_length * predict_young_cards_per_entry_ratio()); 1361 } 1362 1363 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const { 1364 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio()); 1365 } 1366 1367 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const { 1368 if (collector_state()->gcs_are_young()) { 1369 return card_num * get_new_prediction(_cost_per_entry_ms_seq); 1370 } else { 1371 return predict_mixed_rs_scan_time_ms(card_num); 1372 } 1373 } 1374 1375 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const { 1376 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 1377 return card_num * get_new_prediction(_cost_per_entry_ms_seq); 1378 } else { 1379 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq); 1380 } 1381 } 1382 1383 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const { 1384 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 1385 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq); 1386 } else { 1387 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq); 1388 } 1389 } 1390 1391 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const { 1392 if (collector_state()->during_concurrent_mark()) { 1393 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 1394 } else { 1395 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq); 1396 } 1397 } 1398 1399 double G1CollectorPolicy::predict_constant_other_time_ms() const { 1400 return get_new_prediction(_constant_other_time_ms_seq); 1401 } 1402 1403 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const { 1404 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq); 1405 } 1406 1407 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const { 1408 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq); 1409 } 1410 1411 double G1CollectorPolicy::predict_remark_time_ms() const { 1412 return get_new_prediction(_concurrent_mark_remark_times_ms); 1413 } 1414 1415 double G1CollectorPolicy::predict_cleanup_time_ms() const { 1416 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 1417 } 1418 1419 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const { 1420 TruncatedSeq* seq = surv_rate_group->get_seq(age); 1421 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age); 1422 double pred = get_new_prediction(seq); 1423 if (pred > 1.0) { 1424 pred = 1.0; 1425 } 1426 return pred; 1427 } 1428 1429 double G1CollectorPolicy::predict_yg_surv_rate(int age) const { 1430 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 1431 } 1432 1433 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const { 1434 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 1435 } 1436 1437 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards, 1438 size_t scanned_cards) const { 1439 return 1440 predict_rs_update_time_ms(pending_cards) + 1441 predict_rs_scan_time_ms(scanned_cards) + 1442 predict_constant_other_time_ms(); 1443 } 1444 1445 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const { 1446 size_t rs_length = predict_rs_length_diff(); 1447 size_t card_num; 1448 if (collector_state()->gcs_are_young()) { 1449 card_num = predict_young_card_num(rs_length); 1450 } else { 1451 card_num = predict_non_young_card_num(rs_length); 1452 } 1453 return predict_base_elapsed_time_ms(pending_cards, card_num); 1454 } 1455 1456 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const { 1457 size_t bytes_to_copy; 1458 if (hr->is_marked()) 1459 bytes_to_copy = hr->max_live_bytes(); 1460 else { 1461 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant"); 1462 int age = hr->age_in_surv_rate_group(); 1463 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); 1464 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate); 1465 } 1466 return bytes_to_copy; 1467 } 1468 1469 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr, 1470 bool for_young_gc) const { 1471 size_t rs_length = hr->rem_set()->occupied(); 1472 size_t card_num; 1473 1474 // Predicting the number of cards is based on which type of GC 1475 // we're predicting for. 1476 if (for_young_gc) { 1477 card_num = predict_young_card_num(rs_length); 1478 } else { 1479 card_num = predict_non_young_card_num(rs_length); 1480 } 1481 size_t bytes_to_copy = predict_bytes_to_copy(hr); 1482 1483 double region_elapsed_time_ms = 1484 predict_rs_scan_time_ms(card_num) + 1485 predict_object_copy_time_ms(bytes_to_copy); 1486 1487 // The prediction of the "other" time for this region is based 1488 // upon the region type and NOT the GC type. 1489 if (hr->is_young()) { 1490 region_elapsed_time_ms += predict_young_other_time_ms(1); 1491 } else { 1492 region_elapsed_time_ms += predict_non_young_other_time_ms(1); 1493 } 1494 return region_elapsed_time_ms; 1495 } 1496 1497 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length, 1498 uint survivor_cset_region_length) { 1499 _eden_cset_region_length = eden_cset_region_length; 1500 _survivor_cset_region_length = survivor_cset_region_length; 1501 _old_cset_region_length = 0; 1502 } 1503 1504 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) { 1505 _recorded_rs_lengths = rs_lengths; 1506 } 1507 1508 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec, 1509 double elapsed_ms) { 1510 _recent_gc_times_ms->add(elapsed_ms); 1511 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec); 1512 _prev_collection_pause_end_ms = end_time_sec * 1000.0; 1513 } 1514 1515 size_t G1CollectorPolicy::expansion_amount() const { 1516 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0; 1517 double threshold = _gc_overhead_perc; 1518 if (recent_gc_overhead > threshold) { 1519 // We will double the existing space, or take 1520 // G1ExpandByPercentOfAvailable % of the available expansion 1521 // space, whichever is smaller, bounded below by a minimum 1522 // expansion (unless that's all that's left.) 1523 const size_t min_expand_bytes = 1*M; 1524 size_t reserved_bytes = _g1->max_capacity(); 1525 size_t committed_bytes = _g1->capacity(); 1526 size_t uncommitted_bytes = reserved_bytes - committed_bytes; 1527 size_t expand_bytes; 1528 size_t expand_bytes_via_pct = 1529 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100; 1530 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes); 1531 expand_bytes = MAX2(expand_bytes, min_expand_bytes); 1532 expand_bytes = MIN2(expand_bytes, uncommitted_bytes); 1533 1534 ergo_verbose5(ErgoHeapSizing, 1535 "attempt heap expansion", 1536 ergo_format_reason("recent GC overhead higher than " 1537 "threshold after GC") 1538 ergo_format_perc("recent GC overhead") 1539 ergo_format_perc("threshold") 1540 ergo_format_byte("uncommitted") 1541 ergo_format_byte_perc("calculated expansion amount"), 1542 recent_gc_overhead, threshold, 1543 uncommitted_bytes, 1544 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable); 1545 1546 return expand_bytes; 1547 } else { 1548 return 0; 1549 } 1550 } 1551 1552 void G1CollectorPolicy::print_tracing_info() const { 1553 _trace_young_gen_time_data.print(); 1554 _trace_old_gen_time_data.print(); 1555 } 1556 1557 void G1CollectorPolicy::print_yg_surv_rate_info() const { 1558 #ifndef PRODUCT 1559 _short_lived_surv_rate_group->print_surv_rate_summary(); 1560 // add this call for any other surv rate groups 1561 #endif // PRODUCT 1562 } 1563 1564 bool G1CollectorPolicy::is_young_list_full() const { 1565 uint young_list_length = _g1->young_list()->length(); 1566 uint young_list_target_length = _young_list_target_length; 1567 return young_list_length >= young_list_target_length; 1568 } 1569 1570 bool G1CollectorPolicy::can_expand_young_list() const { 1571 uint young_list_length = _g1->young_list()->length(); 1572 uint young_list_max_length = _young_list_max_length; 1573 return young_list_length < young_list_max_length; 1574 } 1575 1576 void G1CollectorPolicy::update_max_gc_locker_expansion() { 1577 uint expansion_region_num = 0; 1578 if (GCLockerEdenExpansionPercent > 0) { 1579 double perc = (double) GCLockerEdenExpansionPercent / 100.0; 1580 double expansion_region_num_d = perc * (double) _young_list_target_length; 1581 // We use ceiling so that if expansion_region_num_d is > 0.0 (but 1582 // less than 1.0) we'll get 1. 1583 expansion_region_num = (uint) ceil(expansion_region_num_d); 1584 } else { 1585 assert(expansion_region_num == 0, "sanity"); 1586 } 1587 _young_list_max_length = _young_list_target_length + expansion_region_num; 1588 assert(_young_list_target_length <= _young_list_max_length, "post-condition"); 1589 } 1590 1591 // Calculates survivor space parameters. 1592 void G1CollectorPolicy::update_survivors_policy() { 1593 double max_survivor_regions_d = 1594 (double) _young_list_target_length / (double) SurvivorRatio; 1595 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but 1596 // smaller than 1.0) we'll get 1. 1597 _max_survivor_regions = (uint) ceil(max_survivor_regions_d); 1598 1599 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold( 1600 HeapRegion::GrainWords * _max_survivor_regions, counters()); 1601 } 1602 1603 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) { 1604 // We actually check whether we are marking here and not if we are in a 1605 // reclamation phase. This means that we will schedule a concurrent mark 1606 // even while we are still in the process of reclaiming memory. 1607 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1608 if (!during_cycle) { 1609 ergo_verbose1(ErgoConcCycles, 1610 "request concurrent cycle initiation", 1611 ergo_format_reason("requested by GC cause") 1612 ergo_format_str("GC cause"), 1613 GCCause::to_string(gc_cause)); 1614 collector_state()->set_initiate_conc_mark_if_possible(true); 1615 return true; 1616 } else { 1617 ergo_verbose1(ErgoConcCycles, 1618 "do not request concurrent cycle initiation", 1619 ergo_format_reason("concurrent cycle already in progress") 1620 ergo_format_str("GC cause"), 1621 GCCause::to_string(gc_cause)); 1622 return false; 1623 } 1624 } 1625 1626 void G1CollectorPolicy::decide_on_conc_mark_initiation() { 1627 // We are about to decide on whether this pause will be an 1628 // initial-mark pause. 1629 1630 // First, collector_state()->during_initial_mark_pause() should not be already set. We 1631 // will set it here if we have to. However, it should be cleared by 1632 // the end of the pause (it's only set for the duration of an 1633 // initial-mark pause). 1634 assert(!collector_state()->during_initial_mark_pause(), "pre-condition"); 1635 1636 if (collector_state()->initiate_conc_mark_if_possible()) { 1637 // We had noticed on a previous pause that the heap occupancy has 1638 // gone over the initiating threshold and we should start a 1639 // concurrent marking cycle. So we might initiate one. 1640 1641 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) { 1642 // Initiate a new initial mark only if there is no marking or reclamation going 1643 // on. 1644 1645 collector_state()->set_during_initial_mark_pause(true); 1646 // And we can now clear initiate_conc_mark_if_possible() as 1647 // we've already acted on it. 1648 collector_state()->set_initiate_conc_mark_if_possible(false); 1649 1650 ergo_verbose0(ErgoConcCycles, 1651 "initiate concurrent cycle", 1652 ergo_format_reason("concurrent cycle initiation requested")); 1653 } else { 1654 // The concurrent marking thread is still finishing up the 1655 // previous cycle. If we start one right now the two cycles 1656 // overlap. In particular, the concurrent marking thread might 1657 // be in the process of clearing the next marking bitmap (which 1658 // we will use for the next cycle if we start one). Starting a 1659 // cycle now will be bad given that parts of the marking 1660 // information might get cleared by the marking thread. And we 1661 // cannot wait for the marking thread to finish the cycle as it 1662 // periodically yields while clearing the next marking bitmap 1663 // and, if it's in a yield point, it's waiting for us to 1664 // finish. So, at this point we will not start a cycle and we'll 1665 // let the concurrent marking thread complete the last one. 1666 ergo_verbose0(ErgoConcCycles, 1667 "do not initiate concurrent cycle", 1668 ergo_format_reason("concurrent cycle already in progress")); 1669 } 1670 } 1671 } 1672 1673 class ParKnownGarbageHRClosure: public HeapRegionClosure { 1674 G1CollectedHeap* _g1h; 1675 CSetChooserParUpdater _cset_updater; 1676 1677 public: 1678 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted, 1679 uint chunk_size) : 1680 _g1h(G1CollectedHeap::heap()), 1681 _cset_updater(hrSorted, true /* parallel */, chunk_size) { } 1682 1683 bool doHeapRegion(HeapRegion* r) { 1684 // Do we have any marking information for this region? 1685 if (r->is_marked()) { 1686 // We will skip any region that's currently used as an old GC 1687 // alloc region (we should not consider those for collection 1688 // before we fill them up). 1689 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1690 _cset_updater.add_region(r); 1691 } 1692 } 1693 return false; 1694 } 1695 }; 1696 1697 class ParKnownGarbageTask: public AbstractGangTask { 1698 CollectionSetChooser* _hrSorted; 1699 uint _chunk_size; 1700 G1CollectedHeap* _g1; 1701 HeapRegionClaimer _hrclaimer; 1702 1703 public: 1704 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) : 1705 AbstractGangTask("ParKnownGarbageTask"), 1706 _hrSorted(hrSorted), _chunk_size(chunk_size), 1707 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {} 1708 1709 void work(uint worker_id) { 1710 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size); 1711 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer); 1712 } 1713 }; 1714 1715 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const { 1716 assert(n_workers > 0, "Active gc workers should be greater than 0"); 1717 const uint overpartition_factor = 4; 1718 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U); 1719 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size); 1720 } 1721 1722 void 1723 G1CollectorPolicy::record_concurrent_mark_cleanup_end() { 1724 _collectionSetChooser->clear(); 1725 1726 WorkGang* workers = _g1->workers(); 1727 uint n_workers = workers->active_workers(); 1728 1729 uint n_regions = _g1->num_regions(); 1730 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions); 1731 _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size); 1732 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers); 1733 workers->run_task(&par_known_garbage_task); 1734 1735 _collectionSetChooser->sort_regions(); 1736 1737 double end_sec = os::elapsedTime(); 1738 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; 1739 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms); 1740 _cur_mark_stop_world_time_ms += elapsed_time_ms; 1741 _prev_collection_pause_end_ms += elapsed_time_ms; 1742 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec); 1743 } 1744 1745 // Add the heap region at the head of the non-incremental collection set 1746 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) { 1747 assert(_inc_cset_build_state == Active, "Precondition"); 1748 assert(hr->is_old(), "the region should be old"); 1749 1750 assert(!hr->in_collection_set(), "should not already be in the CSet"); 1751 _g1->register_old_region_with_cset(hr); 1752 hr->set_next_in_collection_set(_collection_set); 1753 _collection_set = hr; 1754 _collection_set_bytes_used_before += hr->used(); 1755 size_t rs_length = hr->rem_set()->occupied(); 1756 _recorded_rs_lengths += rs_length; 1757 _old_cset_region_length += 1; 1758 } 1759 1760 // Initialize the per-collection-set information 1761 void G1CollectorPolicy::start_incremental_cset_building() { 1762 assert(_inc_cset_build_state == Inactive, "Precondition"); 1763 1764 _inc_cset_head = NULL; 1765 _inc_cset_tail = NULL; 1766 _inc_cset_bytes_used_before = 0; 1767 1768 _inc_cset_max_finger = 0; 1769 _inc_cset_recorded_rs_lengths = 0; 1770 _inc_cset_recorded_rs_lengths_diffs = 0; 1771 _inc_cset_predicted_elapsed_time_ms = 0.0; 1772 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1773 _inc_cset_build_state = Active; 1774 } 1775 1776 void G1CollectorPolicy::finalize_incremental_cset_building() { 1777 assert(_inc_cset_build_state == Active, "Precondition"); 1778 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 1779 1780 // The two "main" fields, _inc_cset_recorded_rs_lengths and 1781 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread 1782 // that adds a new region to the CSet. Further updates by the 1783 // concurrent refinement thread that samples the young RSet lengths 1784 // are accumulated in the *_diffs fields. Here we add the diffs to 1785 // the "main" fields. 1786 1787 if (_inc_cset_recorded_rs_lengths_diffs >= 0) { 1788 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs; 1789 } else { 1790 // This is defensive. The diff should in theory be always positive 1791 // as RSets can only grow between GCs. However, given that we 1792 // sample their size concurrently with other threads updating them 1793 // it's possible that we might get the wrong size back, which 1794 // could make the calculations somewhat inaccurate. 1795 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs); 1796 if (_inc_cset_recorded_rs_lengths >= diffs) { 1797 _inc_cset_recorded_rs_lengths -= diffs; 1798 } else { 1799 _inc_cset_recorded_rs_lengths = 0; 1800 } 1801 } 1802 _inc_cset_predicted_elapsed_time_ms += 1803 _inc_cset_predicted_elapsed_time_ms_diffs; 1804 1805 _inc_cset_recorded_rs_lengths_diffs = 0; 1806 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1807 } 1808 1809 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) { 1810 // This routine is used when: 1811 // * adding survivor regions to the incremental cset at the end of an 1812 // evacuation pause, 1813 // * adding the current allocation region to the incremental cset 1814 // when it is retired, and 1815 // * updating existing policy information for a region in the 1816 // incremental cset via young list RSet sampling. 1817 // Therefore this routine may be called at a safepoint by the 1818 // VM thread, or in-between safepoints by mutator threads (when 1819 // retiring the current allocation region) or a concurrent 1820 // refine thread (RSet sampling). 1821 1822 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 1823 size_t used_bytes = hr->used(); 1824 _inc_cset_recorded_rs_lengths += rs_length; 1825 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms; 1826 _inc_cset_bytes_used_before += used_bytes; 1827 1828 // Cache the values we have added to the aggregated information 1829 // in the heap region in case we have to remove this region from 1830 // the incremental collection set, or it is updated by the 1831 // rset sampling code 1832 hr->set_recorded_rs_length(rs_length); 1833 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms); 1834 } 1835 1836 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, 1837 size_t new_rs_length) { 1838 // Update the CSet information that is dependent on the new RS length 1839 assert(hr->is_young(), "Precondition"); 1840 assert(!SafepointSynchronize::is_at_safepoint(), 1841 "should not be at a safepoint"); 1842 1843 // We could have updated _inc_cset_recorded_rs_lengths and 1844 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do 1845 // that atomically, as this code is executed by a concurrent 1846 // refinement thread, potentially concurrently with a mutator thread 1847 // allocating a new region and also updating the same fields. To 1848 // avoid the atomic operations we accumulate these updates on two 1849 // separate fields (*_diffs) and we'll just add them to the "main" 1850 // fields at the start of a GC. 1851 1852 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length(); 1853 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length; 1854 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff; 1855 1856 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms(); 1857 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 1858 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms; 1859 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff; 1860 1861 hr->set_recorded_rs_length(new_rs_length); 1862 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms); 1863 } 1864 1865 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) { 1866 assert(hr->is_young(), "invariant"); 1867 assert(hr->young_index_in_cset() > -1, "should have already been set"); 1868 assert(_inc_cset_build_state == Active, "Precondition"); 1869 1870 // We need to clear and set the cached recorded/cached collection set 1871 // information in the heap region here (before the region gets added 1872 // to the collection set). An individual heap region's cached values 1873 // are calculated, aggregated with the policy collection set info, 1874 // and cached in the heap region here (initially) and (subsequently) 1875 // by the Young List sampling code. 1876 1877 size_t rs_length = hr->rem_set()->occupied(); 1878 add_to_incremental_cset_info(hr, rs_length); 1879 1880 HeapWord* hr_end = hr->end(); 1881 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end); 1882 1883 assert(!hr->in_collection_set(), "invariant"); 1884 _g1->register_young_region_with_cset(hr); 1885 assert(hr->next_in_collection_set() == NULL, "invariant"); 1886 } 1887 1888 // Add the region at the RHS of the incremental cset 1889 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) { 1890 // We should only ever be appending survivors at the end of a pause 1891 assert(hr->is_survivor(), "Logic"); 1892 1893 // Do the 'common' stuff 1894 add_region_to_incremental_cset_common(hr); 1895 1896 // Now add the region at the right hand side 1897 if (_inc_cset_tail == NULL) { 1898 assert(_inc_cset_head == NULL, "invariant"); 1899 _inc_cset_head = hr; 1900 } else { 1901 _inc_cset_tail->set_next_in_collection_set(hr); 1902 } 1903 _inc_cset_tail = hr; 1904 } 1905 1906 // Add the region to the LHS of the incremental cset 1907 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) { 1908 // Survivors should be added to the RHS at the end of a pause 1909 assert(hr->is_eden(), "Logic"); 1910 1911 // Do the 'common' stuff 1912 add_region_to_incremental_cset_common(hr); 1913 1914 // Add the region at the left hand side 1915 hr->set_next_in_collection_set(_inc_cset_head); 1916 if (_inc_cset_head == NULL) { 1917 assert(_inc_cset_tail == NULL, "Invariant"); 1918 _inc_cset_tail = hr; 1919 } 1920 _inc_cset_head = hr; 1921 } 1922 1923 #ifndef PRODUCT 1924 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) { 1925 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be"); 1926 1927 st->print_cr("\nCollection_set:"); 1928 HeapRegion* csr = list_head; 1929 while (csr != NULL) { 1930 HeapRegion* next = csr->next_in_collection_set(); 1931 assert(csr->in_collection_set(), "bad CS"); 1932 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d", 1933 HR_FORMAT_PARAMS(csr), 1934 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()), 1935 csr->age_in_surv_rate_group_cond()); 1936 csr = next; 1937 } 1938 } 1939 #endif // !PRODUCT 1940 1941 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const { 1942 // Returns the given amount of reclaimable bytes (that represents 1943 // the amount of reclaimable space still to be collected) as a 1944 // percentage of the current heap capacity. 1945 size_t capacity_bytes = _g1->capacity(); 1946 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes; 1947 } 1948 1949 void G1CollectorPolicy::maybe_start_marking() { 1950 if (need_to_start_conc_mark("end of GC")) { 1951 // Note: this might have already been set, if during the last 1952 // pause we decided to start a cycle but at the beginning of 1953 // this pause we decided to postpone it. That's OK. 1954 collector_state()->set_initiate_conc_mark_if_possible(true); 1955 } 1956 } 1957 1958 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str, 1959 const char* false_action_str) const { 1960 CollectionSetChooser* cset_chooser = _collectionSetChooser; 1961 if (cset_chooser->is_empty()) { 1962 ergo_verbose0(ErgoMixedGCs, 1963 false_action_str, 1964 ergo_format_reason("candidate old regions not available")); 1965 return false; 1966 } 1967 1968 // Is the amount of uncollected reclaimable space above G1HeapWastePercent? 1969 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 1970 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 1971 double threshold = (double) G1HeapWastePercent; 1972 if (reclaimable_perc <= threshold) { 1973 ergo_verbose4(ErgoMixedGCs, 1974 false_action_str, 1975 ergo_format_reason("reclaimable percentage not over threshold") 1976 ergo_format_region("candidate old regions") 1977 ergo_format_byte_perc("reclaimable") 1978 ergo_format_perc("threshold"), 1979 cset_chooser->remaining_regions(), 1980 reclaimable_bytes, 1981 reclaimable_perc, threshold); 1982 return false; 1983 } 1984 1985 ergo_verbose4(ErgoMixedGCs, 1986 true_action_str, 1987 ergo_format_reason("candidate old regions available") 1988 ergo_format_region("candidate old regions") 1989 ergo_format_byte_perc("reclaimable") 1990 ergo_format_perc("threshold"), 1991 cset_chooser->remaining_regions(), 1992 reclaimable_bytes, 1993 reclaimable_perc, threshold); 1994 return true; 1995 } 1996 1997 uint G1CollectorPolicy::calc_min_old_cset_length() const { 1998 // The min old CSet region bound is based on the maximum desired 1999 // number of mixed GCs after a cycle. I.e., even if some old regions 2000 // look expensive, we should add them to the CSet anyway to make 2001 // sure we go through the available old regions in no more than the 2002 // maximum desired number of mixed GCs. 2003 // 2004 // The calculation is based on the number of marked regions we added 2005 // to the CSet chooser in the first place, not how many remain, so 2006 // that the result is the same during all mixed GCs that follow a cycle. 2007 2008 const size_t region_num = (size_t) _collectionSetChooser->length(); 2009 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); 2010 size_t result = region_num / gc_num; 2011 // emulate ceiling 2012 if (result * gc_num < region_num) { 2013 result += 1; 2014 } 2015 return (uint) result; 2016 } 2017 2018 uint G1CollectorPolicy::calc_max_old_cset_length() const { 2019 // The max old CSet region bound is based on the threshold expressed 2020 // as a percentage of the heap size. I.e., it should bound the 2021 // number of old regions added to the CSet irrespective of how many 2022 // of them are available. 2023 2024 const G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2025 const size_t region_num = g1h->num_regions(); 2026 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; 2027 size_t result = region_num * perc / 100; 2028 // emulate ceiling 2029 if (100 * result < region_num * perc) { 2030 result += 1; 2031 } 2032 return (uint) result; 2033 } 2034 2035 2036 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) { 2037 double young_start_time_sec = os::elapsedTime(); 2038 2039 YoungList* young_list = _g1->young_list(); 2040 finalize_incremental_cset_building(); 2041 2042 guarantee(target_pause_time_ms > 0.0, 2043 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms); 2044 guarantee(_collection_set == NULL, "Precondition"); 2045 2046 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards); 2047 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0); 2048 2049 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 2050 "start choosing CSet", 2051 ergo_format_size("_pending_cards") 2052 ergo_format_ms("predicted base time") 2053 ergo_format_ms("remaining time") 2054 ergo_format_ms("target pause time"), 2055 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms); 2056 2057 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young()); 2058 2059 if (collector_state()->last_gc_was_young()) { 2060 _trace_young_gen_time_data.increment_young_collection_count(); 2061 } else { 2062 _trace_young_gen_time_data.increment_mixed_collection_count(); 2063 } 2064 2065 // The young list is laid with the survivor regions from the previous 2066 // pause are appended to the RHS of the young list, i.e. 2067 // [Newly Young Regions ++ Survivors from last pause]. 2068 2069 uint survivor_region_length = young_list->survivor_length(); 2070 uint eden_region_length = young_list->eden_length(); 2071 init_cset_region_lengths(eden_region_length, survivor_region_length); 2072 2073 HeapRegion* hr = young_list->first_survivor_region(); 2074 while (hr != NULL) { 2075 assert(hr->is_survivor(), "badly formed young list"); 2076 // There is a convention that all the young regions in the CSet 2077 // are tagged as "eden", so we do this for the survivors here. We 2078 // use the special set_eden_pre_gc() as it doesn't check that the 2079 // region is free (which is not the case here). 2080 hr->set_eden_pre_gc(); 2081 hr = hr->get_next_young_region(); 2082 } 2083 2084 // Clear the fields that point to the survivor list - they are all young now. 2085 young_list->clear_survivors(); 2086 2087 _collection_set = _inc_cset_head; 2088 _collection_set_bytes_used_before = _inc_cset_bytes_used_before; 2089 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0); 2090 2091 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 2092 "add young regions to CSet", 2093 ergo_format_region("eden") 2094 ergo_format_region("survivors") 2095 ergo_format_ms("predicted young region time") 2096 ergo_format_ms("target pause time"), 2097 eden_region_length, survivor_region_length, 2098 _inc_cset_predicted_elapsed_time_ms, 2099 target_pause_time_ms); 2100 2101 // The number of recorded young regions is the incremental 2102 // collection set's current size 2103 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths); 2104 2105 double young_end_time_sec = os::elapsedTime(); 2106 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0); 2107 2108 return time_remaining_ms; 2109 } 2110 2111 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) { 2112 double non_young_start_time_sec = os::elapsedTime(); 2113 double predicted_old_time_ms = 0.0; 2114 2115 2116 if (!collector_state()->gcs_are_young()) { 2117 CollectionSetChooser* cset_chooser = _collectionSetChooser; 2118 cset_chooser->verify(); 2119 const uint min_old_cset_length = calc_min_old_cset_length(); 2120 const uint max_old_cset_length = calc_max_old_cset_length(); 2121 2122 uint expensive_region_num = 0; 2123 bool check_time_remaining = adaptive_young_list_length(); 2124 2125 HeapRegion* hr = cset_chooser->peek(); 2126 while (hr != NULL) { 2127 if (old_cset_region_length() >= max_old_cset_length) { 2128 // Added maximum number of old regions to the CSet. 2129 ergo_verbose2(ErgoCSetConstruction, 2130 "finish adding old regions to CSet", 2131 ergo_format_reason("old CSet region num reached max") 2132 ergo_format_region("old") 2133 ergo_format_region("max"), 2134 old_cset_region_length(), max_old_cset_length); 2135 break; 2136 } 2137 2138 2139 // Stop adding regions if the remaining reclaimable space is 2140 // not above G1HeapWastePercent. 2141 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 2142 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 2143 double threshold = (double) G1HeapWastePercent; 2144 if (reclaimable_perc <= threshold) { 2145 // We've added enough old regions that the amount of uncollected 2146 // reclaimable space is at or below the waste threshold. Stop 2147 // adding old regions to the CSet. 2148 ergo_verbose5(ErgoCSetConstruction, 2149 "finish adding old regions to CSet", 2150 ergo_format_reason("reclaimable percentage not over threshold") 2151 ergo_format_region("old") 2152 ergo_format_region("max") 2153 ergo_format_byte_perc("reclaimable") 2154 ergo_format_perc("threshold"), 2155 old_cset_region_length(), 2156 max_old_cset_length, 2157 reclaimable_bytes, 2158 reclaimable_perc, threshold); 2159 break; 2160 } 2161 2162 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 2163 if (check_time_remaining) { 2164 if (predicted_time_ms > time_remaining_ms) { 2165 // Too expensive for the current CSet. 2166 2167 if (old_cset_region_length() >= min_old_cset_length) { 2168 // We have added the minimum number of old regions to the CSet, 2169 // we are done with this CSet. 2170 ergo_verbose4(ErgoCSetConstruction, 2171 "finish adding old regions to CSet", 2172 ergo_format_reason("predicted time is too high") 2173 ergo_format_ms("predicted time") 2174 ergo_format_ms("remaining time") 2175 ergo_format_region("old") 2176 ergo_format_region("min"), 2177 predicted_time_ms, time_remaining_ms, 2178 old_cset_region_length(), min_old_cset_length); 2179 break; 2180 } 2181 2182 // We'll add it anyway given that we haven't reached the 2183 // minimum number of old regions. 2184 expensive_region_num += 1; 2185 } 2186 } else { 2187 if (old_cset_region_length() >= min_old_cset_length) { 2188 // In the non-auto-tuning case, we'll finish adding regions 2189 // to the CSet if we reach the minimum. 2190 ergo_verbose2(ErgoCSetConstruction, 2191 "finish adding old regions to CSet", 2192 ergo_format_reason("old CSet region num reached min") 2193 ergo_format_region("old") 2194 ergo_format_region("min"), 2195 old_cset_region_length(), min_old_cset_length); 2196 break; 2197 } 2198 } 2199 2200 // We will add this region to the CSet. 2201 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); 2202 predicted_old_time_ms += predicted_time_ms; 2203 cset_chooser->pop(); // already have region via peek() 2204 _g1->old_set_remove(hr); 2205 add_old_region_to_cset(hr); 2206 2207 hr = cset_chooser->peek(); 2208 } 2209 if (hr == NULL) { 2210 ergo_verbose0(ErgoCSetConstruction, 2211 "finish adding old regions to CSet", 2212 ergo_format_reason("candidate old regions not available")); 2213 } 2214 2215 if (expensive_region_num > 0) { 2216 // We print the information once here at the end, predicated on 2217 // whether we added any apparently expensive regions or not, to 2218 // avoid generating output per region. 2219 ergo_verbose4(ErgoCSetConstruction, 2220 "added expensive regions to CSet", 2221 ergo_format_reason("old CSet region num not reached min") 2222 ergo_format_region("old") 2223 ergo_format_region("expensive") 2224 ergo_format_region("min") 2225 ergo_format_ms("remaining time"), 2226 old_cset_region_length(), 2227 expensive_region_num, 2228 min_old_cset_length, 2229 time_remaining_ms); 2230 } 2231 2232 cset_chooser->verify(); 2233 } 2234 2235 stop_incremental_cset_building(); 2236 2237 ergo_verbose3(ErgoCSetConstruction, 2238 "finish choosing CSet", 2239 ergo_format_region("old") 2240 ergo_format_ms("predicted old region time") 2241 ergo_format_ms("time remaining"), 2242 old_cset_region_length(), 2243 predicted_old_time_ms, time_remaining_ms); 2244 2245 double non_young_end_time_sec = os::elapsedTime(); 2246 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); 2247 } 2248 2249 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) { 2250 if(TraceYoungGenTime) { 2251 _all_stop_world_times_ms.add(time_to_stop_the_world_ms); 2252 } 2253 } 2254 2255 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) { 2256 if(TraceYoungGenTime) { 2257 _all_yield_times_ms.add(yield_time_ms); 2258 } 2259 } 2260 2261 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) { 2262 if(TraceYoungGenTime) { 2263 _total.add(pause_time_ms); 2264 _other.add(pause_time_ms - phase_times->accounted_time_ms()); 2265 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms()); 2266 _parallel.add(phase_times->cur_collection_par_time_ms()); 2267 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan)); 2268 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering)); 2269 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS)); 2270 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS)); 2271 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy)); 2272 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination)); 2273 2274 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) + 2275 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) + 2276 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) + 2277 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) + 2278 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) + 2279 phase_times->average_time_ms(G1GCPhaseTimes::Termination); 2280 2281 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time; 2282 _parallel_other.add(parallel_other_time); 2283 _clear_ct.add(phase_times->cur_clear_ct_time_ms()); 2284 } 2285 } 2286 2287 void TraceYoungGenTimeData::increment_young_collection_count() { 2288 if(TraceYoungGenTime) { 2289 ++_young_pause_num; 2290 } 2291 } 2292 2293 void TraceYoungGenTimeData::increment_mixed_collection_count() { 2294 if(TraceYoungGenTime) { 2295 ++_mixed_pause_num; 2296 } 2297 } 2298 2299 void TraceYoungGenTimeData::print_summary(const char* str, 2300 const NumberSeq* seq) const { 2301 double sum = seq->sum(); 2302 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)", 2303 str, sum / 1000.0, seq->avg()); 2304 } 2305 2306 void TraceYoungGenTimeData::print_summary_sd(const char* str, 2307 const NumberSeq* seq) const { 2308 print_summary(str, seq); 2309 gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)", 2310 "(num", seq->num(), seq->sd(), seq->maximum()); 2311 } 2312 2313 void TraceYoungGenTimeData::print() const { 2314 if (!TraceYoungGenTime) { 2315 return; 2316 } 2317 2318 gclog_or_tty->print_cr("ALL PAUSES"); 2319 print_summary_sd(" Total", &_total); 2320 gclog_or_tty->cr(); 2321 gclog_or_tty->cr(); 2322 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num); 2323 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num); 2324 gclog_or_tty->cr(); 2325 2326 gclog_or_tty->print_cr("EVACUATION PAUSES"); 2327 2328 if (_young_pause_num == 0 && _mixed_pause_num == 0) { 2329 gclog_or_tty->print_cr("none"); 2330 } else { 2331 print_summary_sd(" Evacuation Pauses", &_total); 2332 print_summary(" Root Region Scan Wait", &_root_region_scan_wait); 2333 print_summary(" Parallel Time", &_parallel); 2334 print_summary(" Ext Root Scanning", &_ext_root_scan); 2335 print_summary(" SATB Filtering", &_satb_filtering); 2336 print_summary(" Update RS", &_update_rs); 2337 print_summary(" Scan RS", &_scan_rs); 2338 print_summary(" Object Copy", &_obj_copy); 2339 print_summary(" Termination", &_termination); 2340 print_summary(" Parallel Other", &_parallel_other); 2341 print_summary(" Clear CT", &_clear_ct); 2342 print_summary(" Other", &_other); 2343 } 2344 gclog_or_tty->cr(); 2345 2346 gclog_or_tty->print_cr("MISC"); 2347 print_summary_sd(" Stop World", &_all_stop_world_times_ms); 2348 print_summary_sd(" Yields", &_all_yield_times_ms); 2349 } 2350 2351 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) { 2352 if (TraceOldGenTime) { 2353 _all_full_gc_times.add(full_gc_time_ms); 2354 } 2355 } 2356 2357 void TraceOldGenTimeData::print() const { 2358 if (!TraceOldGenTime) { 2359 return; 2360 } 2361 2362 if (_all_full_gc_times.num() > 0) { 2363 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s", 2364 _all_full_gc_times.num(), 2365 _all_full_gc_times.sum() / 1000.0); 2366 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg()); 2367 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]", 2368 _all_full_gc_times.sd(), 2369 _all_full_gc_times.maximum()); 2370 } 2371 }