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/g1IHOPControl.hpp" 32 #include "gc/g1/g1ErgoVerbose.hpp" 33 #include "gc/g1/g1GCPhaseTimes.hpp" 34 #include "gc/g1/g1Log.hpp" 35 #include "gc/g1/heapRegion.inline.hpp" 36 #include "gc/g1/heapRegionRemSet.hpp" 37 #include "gc/shared/gcPolicyCounters.hpp" 38 #include "runtime/arguments.hpp" 39 #include "runtime/java.hpp" 40 #include "runtime/mutexLocker.hpp" 41 #include "utilities/debug.hpp" 42 #include "utilities/pair.hpp" 43 44 // Different defaults for different number of GC threads 45 // They were chosen by running GCOld and SPECjbb on debris with different 46 // numbers of GC threads and choosing them based on the results 47 48 // all the same 49 static double rs_length_diff_defaults[] = { 50 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 51 }; 52 53 static double cost_per_card_ms_defaults[] = { 54 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015 55 }; 56 57 // all the same 58 static double young_cards_per_entry_ratio_defaults[] = { 59 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 60 }; 61 62 static double cost_per_entry_ms_defaults[] = { 63 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005 64 }; 65 66 static double cost_per_byte_ms_defaults[] = { 67 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009 68 }; 69 70 // these should be pretty consistent 71 static double constant_other_time_ms_defaults[] = { 72 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 73 }; 74 75 76 static double young_other_cost_per_region_ms_defaults[] = { 77 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1 78 }; 79 80 static double non_young_other_cost_per_region_ms_defaults[] = { 81 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30 82 }; 83 84 G1CollectorPolicy::G1CollectorPolicy() : 85 _predictor(G1ConfidencePercent / 100.0), 86 _parallel_gc_threads(ParallelGCThreads), 87 88 _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 89 _stop_world_start(0.0), 90 91 _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 92 _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)), 93 94 _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 95 _prev_collection_pause_end_ms(0.0), 96 _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)), 97 _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 98 _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)), 99 _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)), 100 _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)), 101 _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 102 _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 103 _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 104 _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)), 105 _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 106 _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)), 107 _non_young_other_cost_per_region_ms_seq( 108 new TruncatedSeq(TruncatedSeqLength)), 109 110 _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)), 111 _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)), 112 113 _pause_time_target_ms((double) MaxGCPauseMillis), 114 115 _recent_prev_end_times_for_all_gcs_sec( 116 new TruncatedSeq(NumPrevPausesForHeuristics)), 117 118 _recent_avg_pause_time_ratio(0.0), 119 _rs_lengths_prediction(0), 120 _max_survivor_regions(0), 121 122 _eden_used_bytes_before_gc(0), 123 _survivor_used_bytes_before_gc(0), 124 _heap_used_bytes_before_gc(0), 125 _metaspace_used_bytes_before_gc(0), 126 _eden_capacity_bytes_before_gc(0), 127 _heap_capacity_bytes_before_gc(0), 128 129 _eden_cset_region_length(0), 130 _survivor_cset_region_length(0), 131 _old_cset_region_length(0), 132 133 _collection_set(NULL), 134 _collection_set_bytes_used_before(0), 135 136 // Incremental CSet attributes 137 _inc_cset_build_state(Inactive), 138 _inc_cset_head(NULL), 139 _inc_cset_tail(NULL), 140 _inc_cset_bytes_used_before(0), 141 _inc_cset_max_finger(NULL), 142 _inc_cset_recorded_rs_lengths(0), 143 _inc_cset_recorded_rs_lengths_diffs(0), 144 _inc_cset_predicted_elapsed_time_ms(0.0), 145 _inc_cset_predicted_elapsed_time_ms_diffs(0.0), 146 147 // add here any more surv rate groups 148 _recorded_survivor_regions(0), 149 _recorded_survivor_head(NULL), 150 _recorded_survivor_tail(NULL), 151 _survivors_age_table(true), 152 153 _gc_overhead_perc(0.0), 154 155 _bytes_allocated_in_old_since_last_gc(0), 156 _ihop_control(NULL), 157 _initial_mark_to_mixed() { 158 159 // SurvRateGroups below must be initialized after the predictor because they 160 // indirectly use it through this object passed to their constructor. 161 _short_lived_surv_rate_group = 162 new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary); 163 _survivor_surv_rate_group = 164 new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary); 165 166 // Set up the region size and associated fields. Given that the 167 // policy is created before the heap, we have to set this up here, 168 // so it's done as soon as possible. 169 170 // It would have been natural to pass initial_heap_byte_size() and 171 // max_heap_byte_size() to setup_heap_region_size() but those have 172 // not been set up at this point since they should be aligned with 173 // the region size. So, there is a circular dependency here. We base 174 // the region size on the heap size, but the heap size should be 175 // aligned with the region size. To get around this we use the 176 // unaligned values for the heap. 177 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize); 178 HeapRegionRemSet::setup_remset_size(); 179 180 G1ErgoVerbose::initialize(); 181 if (PrintAdaptiveSizePolicy) { 182 // Currently, we only use a single switch for all the heuristics. 183 G1ErgoVerbose::set_enabled(true); 184 // Given that we don't currently have a verboseness level 185 // parameter, we'll hardcode this to high. This can be easily 186 // changed in the future. 187 G1ErgoVerbose::set_level(ErgoHigh); 188 } else { 189 G1ErgoVerbose::set_enabled(false); 190 } 191 192 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime()); 193 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0; 194 195 _phase_times = new G1GCPhaseTimes(_parallel_gc_threads); 196 197 int index = MIN2(_parallel_gc_threads - 1, 7); 198 199 _rs_length_diff_seq->add(rs_length_diff_defaults[index]); 200 _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]); 201 _cost_scan_hcc_seq->add(0.0); 202 _young_cards_per_entry_ratio_seq->add( 203 young_cards_per_entry_ratio_defaults[index]); 204 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]); 205 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]); 206 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]); 207 _young_other_cost_per_region_ms_seq->add( 208 young_other_cost_per_region_ms_defaults[index]); 209 _non_young_other_cost_per_region_ms_seq->add( 210 non_young_other_cost_per_region_ms_defaults[index]); 211 212 // Below, we might need to calculate the pause time target based on 213 // the pause interval. When we do so we are going to give G1 maximum 214 // flexibility and allow it to do pauses when it needs to. So, we'll 215 // arrange that the pause interval to be pause time target + 1 to 216 // ensure that a) the pause time target is maximized with respect to 217 // the pause interval and b) we maintain the invariant that pause 218 // time target < pause interval. If the user does not want this 219 // maximum flexibility, they will have to set the pause interval 220 // explicitly. 221 222 // First make sure that, if either parameter is set, its value is 223 // reasonable. 224 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 225 if (MaxGCPauseMillis < 1) { 226 vm_exit_during_initialization("MaxGCPauseMillis should be " 227 "greater than 0"); 228 } 229 } 230 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 231 if (GCPauseIntervalMillis < 1) { 232 vm_exit_during_initialization("GCPauseIntervalMillis should be " 233 "greater than 0"); 234 } 235 } 236 237 // Then, if the pause time target parameter was not set, set it to 238 // the default value. 239 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 240 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 241 // The default pause time target in G1 is 200ms 242 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200); 243 } else { 244 // We do not allow the pause interval to be set without the 245 // pause time target 246 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set " 247 "without setting MaxGCPauseMillis"); 248 } 249 } 250 251 // Then, if the interval parameter was not set, set it according to 252 // the pause time target (this will also deal with the case when the 253 // pause time target is the default value). 254 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 255 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1); 256 } 257 258 // Finally, make sure that the two parameters are consistent. 259 if (MaxGCPauseMillis >= GCPauseIntervalMillis) { 260 char buffer[256]; 261 jio_snprintf(buffer, 256, 262 "MaxGCPauseMillis (%u) should be less than " 263 "GCPauseIntervalMillis (%u)", 264 MaxGCPauseMillis, GCPauseIntervalMillis); 265 vm_exit_during_initialization(buffer); 266 } 267 268 double max_gc_time = (double) MaxGCPauseMillis / 1000.0; 269 double time_slice = (double) GCPauseIntervalMillis / 1000.0; 270 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time); 271 272 // start conservatively (around 50ms is about right) 273 _concurrent_mark_remark_times_ms->add(0.05); 274 _concurrent_mark_cleanup_times_ms->add(0.20); 275 _tenuring_threshold = MaxTenuringThreshold; 276 277 assert(GCTimeRatio > 0, 278 "we should have set it to a default value set_g1_gc_flags() " 279 "if a user set it to 0"); 280 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio)); 281 282 uintx reserve_perc = G1ReservePercent; 283 // Put an artificial ceiling on this so that it's not set to a silly value. 284 if (reserve_perc > 50) { 285 reserve_perc = 50; 286 warning("G1ReservePercent is set to a value that is too large, " 287 "it's been updated to " UINTX_FORMAT, reserve_perc); 288 } 289 _reserve_factor = (double) reserve_perc / 100.0; 290 // This will be set when the heap is expanded 291 // for the first time during initialization. 292 _reserve_regions = 0; 293 294 _collectionSetChooser = new CollectionSetChooser(); 295 } 296 297 G1CollectorPolicy::~G1CollectorPolicy() { 298 delete _ihop_control; 299 } 300 301 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const { 302 return _predictor.get_new_prediction(seq); 303 } 304 305 void G1CollectorPolicy::initialize_alignments() { 306 _space_alignment = HeapRegion::GrainBytes; 307 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint(); 308 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 309 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size); 310 } 311 312 void G1CollectorPolicy::initialize_flags() { 313 if (G1HeapRegionSize != HeapRegion::GrainBytes) { 314 FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes); 315 } 316 317 if (SurvivorRatio < 1) { 318 vm_exit_during_initialization("Invalid survivor ratio specified"); 319 } 320 CollectorPolicy::initialize_flags(); 321 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags 322 } 323 324 void G1CollectorPolicy::post_heap_initialize() { 325 uintx max_regions = G1CollectedHeap::heap()->max_regions(); 326 size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes; 327 if (max_young_size != MaxNewSize) { 328 FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size); 329 } 330 331 _ihop_control = create_ihop_control(); 332 } 333 334 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); } 335 336 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true), 337 _min_desired_young_length(0), _max_desired_young_length(0) { 338 if (FLAG_IS_CMDLINE(NewRatio)) { 339 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) { 340 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio"); 341 } else { 342 _sizer_kind = SizerNewRatio; 343 _adaptive_size = false; 344 return; 345 } 346 } 347 348 if (NewSize > MaxNewSize) { 349 if (FLAG_IS_CMDLINE(MaxNewSize)) { 350 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). " 351 "A new max generation size of " SIZE_FORMAT "k will be used.", 352 NewSize/K, MaxNewSize/K, NewSize/K); 353 } 354 MaxNewSize = NewSize; 355 } 356 357 if (FLAG_IS_CMDLINE(NewSize)) { 358 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes), 359 1U); 360 if (FLAG_IS_CMDLINE(MaxNewSize)) { 361 _max_desired_young_length = 362 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 363 1U); 364 _sizer_kind = SizerMaxAndNewSize; 365 _adaptive_size = _min_desired_young_length == _max_desired_young_length; 366 } else { 367 _sizer_kind = SizerNewSizeOnly; 368 } 369 } else if (FLAG_IS_CMDLINE(MaxNewSize)) { 370 _max_desired_young_length = 371 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 372 1U); 373 _sizer_kind = SizerMaxNewSizeOnly; 374 } 375 } 376 377 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) { 378 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100; 379 return MAX2(1U, default_value); 380 } 381 382 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) { 383 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100; 384 return MAX2(1U, default_value); 385 } 386 387 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) { 388 assert(number_of_heap_regions > 0, "Heap must be initialized"); 389 390 switch (_sizer_kind) { 391 case SizerDefaults: 392 *min_young_length = calculate_default_min_length(number_of_heap_regions); 393 *max_young_length = calculate_default_max_length(number_of_heap_regions); 394 break; 395 case SizerNewSizeOnly: 396 *max_young_length = calculate_default_max_length(number_of_heap_regions); 397 *max_young_length = MAX2(*min_young_length, *max_young_length); 398 break; 399 case SizerMaxNewSizeOnly: 400 *min_young_length = calculate_default_min_length(number_of_heap_regions); 401 *min_young_length = MIN2(*min_young_length, *max_young_length); 402 break; 403 case SizerMaxAndNewSize: 404 // Do nothing. Values set on the command line, don't update them at runtime. 405 break; 406 case SizerNewRatio: 407 *min_young_length = number_of_heap_regions / (NewRatio + 1); 408 *max_young_length = *min_young_length; 409 break; 410 default: 411 ShouldNotReachHere(); 412 } 413 414 assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values"); 415 } 416 417 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) { 418 // We need to pass the desired values because recalculation may not update these 419 // values in some cases. 420 uint temp = _min_desired_young_length; 421 uint result = _max_desired_young_length; 422 recalculate_min_max_young_length(number_of_heap_regions, &temp, &result); 423 return result; 424 } 425 426 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) { 427 recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length, 428 &_max_desired_young_length); 429 } 430 431 void G1CollectorPolicy::init() { 432 // Set aside an initial future to_space. 433 _g1 = G1CollectedHeap::heap(); 434 435 assert(Heap_lock->owned_by_self(), "Locking discipline."); 436 437 initialize_gc_policy_counters(); 438 439 if (adaptive_young_list_length()) { 440 _young_list_fixed_length = 0; 441 } else { 442 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length(); 443 } 444 _free_regions_at_end_of_collection = _g1->num_free_regions(); 445 446 update_young_list_max_and_target_length(); 447 // We may immediately start allocating regions and placing them on the 448 // collection set list. Initialize the per-collection set info 449 start_incremental_cset_building(); 450 } 451 452 void G1CollectorPolicy::note_gc_start(uint num_active_workers) { 453 phase_times()->note_gc_start(num_active_workers); 454 } 455 456 // Create the jstat counters for the policy. 457 void G1CollectorPolicy::initialize_gc_policy_counters() { 458 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3); 459 } 460 461 bool G1CollectorPolicy::predict_will_fit(uint young_length, 462 double base_time_ms, 463 uint base_free_regions, 464 double target_pause_time_ms) const { 465 if (young_length >= base_free_regions) { 466 // end condition 1: not enough space for the young regions 467 return false; 468 } 469 470 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1); 471 size_t bytes_to_copy = 472 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); 473 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy); 474 double young_other_time_ms = predict_young_other_time_ms(young_length); 475 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms; 476 if (pause_time_ms > target_pause_time_ms) { 477 // end condition 2: prediction is over the target pause time 478 return false; 479 } 480 481 size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes; 482 483 // When copying, we will likely need more bytes free than is live in the region. 484 // Add some safety margin to factor in the confidence of our guess, and the 485 // natural expected waste. 486 // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty 487 // of the calculation: the lower the confidence, the more headroom. 488 // (100 + TargetPLABWastePct) represents the increase in expected bytes during 489 // copying due to anticipated waste in the PLABs. 490 double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0; 491 size_t expected_bytes_to_copy = safety_factor * bytes_to_copy; 492 493 if (expected_bytes_to_copy > free_bytes) { 494 // end condition 3: out-of-space 495 return false; 496 } 497 498 // success! 499 return true; 500 } 501 502 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) { 503 // re-calculate the necessary reserve 504 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; 505 // We use ceiling so that if reserve_regions_d is > 0.0 (but 506 // smaller than 1.0) we'll get 1. 507 _reserve_regions = (uint) ceil(reserve_regions_d); 508 509 _young_gen_sizer->heap_size_changed(new_number_of_regions); 510 } 511 512 uint G1CollectorPolicy::calculate_young_list_desired_min_length( 513 uint base_min_length) const { 514 uint desired_min_length = 0; 515 if (adaptive_young_list_length()) { 516 if (_alloc_rate_ms_seq->num() > 3) { 517 double now_sec = os::elapsedTime(); 518 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; 519 double alloc_rate_ms = predict_alloc_rate_ms(); 520 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); 521 } else { 522 // otherwise we don't have enough info to make the prediction 523 } 524 } 525 desired_min_length += base_min_length; 526 // make sure we don't go below any user-defined minimum bound 527 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length); 528 } 529 530 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const { 531 // Here, we might want to also take into account any additional 532 // constraints (i.e., user-defined minimum bound). Currently, we 533 // effectively don't set this bound. 534 return _young_gen_sizer->max_desired_young_length(); 535 } 536 537 uint G1CollectorPolicy::update_young_list_max_and_target_length() { 538 return update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq)); 539 } 540 541 uint G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) { 542 uint unbounded_target_length = update_young_list_target_length(rs_lengths); 543 update_max_gc_locker_expansion(); 544 return unbounded_target_length; 545 } 546 547 uint G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) { 548 YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths); 549 _young_list_target_length = young_lengths.first; 550 return young_lengths.second; 551 } 552 553 G1CollectorPolicy::YoungTargetLengths G1CollectorPolicy::young_list_target_lengths(size_t rs_lengths) const { 554 YoungTargetLengths result; 555 556 // Calculate the absolute and desired min bounds first. 557 558 // This is how many young regions we already have (currently: the survivors). 559 uint base_min_length = recorded_survivor_regions(); 560 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length); 561 // This is the absolute minimum young length. Ensure that we 562 // will at least have one eden region available for allocation. 563 uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1); 564 // If we shrank the young list target it should not shrink below the current size. 565 desired_min_length = MAX2(desired_min_length, absolute_min_length); 566 // Calculate the absolute and desired max bounds. 567 568 uint desired_max_length = calculate_young_list_desired_max_length(); 569 570 uint young_list_target_length = 0; 571 if (adaptive_young_list_length()) { 572 if (collector_state()->gcs_are_young()) { 573 young_list_target_length = 574 calculate_young_list_target_length(rs_lengths, 575 base_min_length, 576 desired_min_length, 577 desired_max_length); 578 } else { 579 // Don't calculate anything and let the code below bound it to 580 // the desired_min_length, i.e., do the next GC as soon as 581 // possible to maximize how many old regions we can add to it. 582 } 583 } else { 584 // The user asked for a fixed young gen so we'll fix the young gen 585 // whether the next GC is young or mixed. 586 young_list_target_length = _young_list_fixed_length; 587 } 588 589 result.second = young_list_target_length; 590 591 // We will try our best not to "eat" into the reserve. 592 uint absolute_max_length = 0; 593 if (_free_regions_at_end_of_collection > _reserve_regions) { 594 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; 595 } 596 if (desired_max_length > absolute_max_length) { 597 desired_max_length = absolute_max_length; 598 } 599 600 // Make sure we don't go over the desired max length, nor under the 601 // desired min length. In case they clash, desired_min_length wins 602 // which is why that test is second. 603 if (young_list_target_length > desired_max_length) { 604 young_list_target_length = desired_max_length; 605 } 606 if (young_list_target_length < desired_min_length) { 607 young_list_target_length = desired_min_length; 608 } 609 610 assert(young_list_target_length > recorded_survivor_regions(), 611 "we should be able to allocate at least one eden region"); 612 assert(young_list_target_length >= absolute_min_length, "post-condition"); 613 614 result.first = young_list_target_length; 615 return result; 616 } 617 618 uint 619 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths, 620 uint base_min_length, 621 uint desired_min_length, 622 uint desired_max_length) const { 623 assert(adaptive_young_list_length(), "pre-condition"); 624 assert(collector_state()->gcs_are_young(), "only call this for young GCs"); 625 626 // In case some edge-condition makes the desired max length too small... 627 if (desired_max_length <= desired_min_length) { 628 return desired_min_length; 629 } 630 631 // We'll adjust min_young_length and max_young_length not to include 632 // the already allocated young regions (i.e., so they reflect the 633 // min and max eden regions we'll allocate). The base_min_length 634 // will be reflected in the predictions by the 635 // survivor_regions_evac_time prediction. 636 assert(desired_min_length > base_min_length, "invariant"); 637 uint min_young_length = desired_min_length - base_min_length; 638 assert(desired_max_length > base_min_length, "invariant"); 639 uint max_young_length = desired_max_length - base_min_length; 640 641 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; 642 double survivor_regions_evac_time = predict_survivor_regions_evac_time(); 643 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq); 644 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff(); 645 size_t scanned_cards = predict_young_card_num(adj_rs_lengths); 646 double base_time_ms = 647 predict_base_elapsed_time_ms(pending_cards, scanned_cards) + 648 survivor_regions_evac_time; 649 uint available_free_regions = _free_regions_at_end_of_collection; 650 uint base_free_regions = 0; 651 if (available_free_regions > _reserve_regions) { 652 base_free_regions = available_free_regions - _reserve_regions; 653 } 654 655 // Here, we will make sure that the shortest young length that 656 // makes sense fits within the target pause time. 657 658 if (predict_will_fit(min_young_length, base_time_ms, 659 base_free_regions, target_pause_time_ms)) { 660 // The shortest young length will fit into the target pause time; 661 // we'll now check whether the absolute maximum number of young 662 // regions will fit in the target pause time. If not, we'll do 663 // a binary search between min_young_length and max_young_length. 664 if (predict_will_fit(max_young_length, base_time_ms, 665 base_free_regions, target_pause_time_ms)) { 666 // The maximum young length will fit into the target pause time. 667 // We are done so set min young length to the maximum length (as 668 // the result is assumed to be returned in min_young_length). 669 min_young_length = max_young_length; 670 } else { 671 // The maximum possible number of young regions will not fit within 672 // the target pause time so we'll search for the optimal 673 // length. The loop invariants are: 674 // 675 // min_young_length < max_young_length 676 // min_young_length is known to fit into the target pause time 677 // max_young_length is known not to fit into the target pause time 678 // 679 // Going into the loop we know the above hold as we've just 680 // checked them. Every time around the loop we check whether 681 // the middle value between min_young_length and 682 // max_young_length fits into the target pause time. If it 683 // does, it becomes the new min. If it doesn't, it becomes 684 // the new max. This way we maintain the loop invariants. 685 686 assert(min_young_length < max_young_length, "invariant"); 687 uint diff = (max_young_length - min_young_length) / 2; 688 while (diff > 0) { 689 uint young_length = min_young_length + diff; 690 if (predict_will_fit(young_length, base_time_ms, 691 base_free_regions, target_pause_time_ms)) { 692 min_young_length = young_length; 693 } else { 694 max_young_length = young_length; 695 } 696 assert(min_young_length < max_young_length, "invariant"); 697 diff = (max_young_length - min_young_length) / 2; 698 } 699 // The results is min_young_length which, according to the 700 // loop invariants, should fit within the target pause time. 701 702 // These are the post-conditions of the binary search above: 703 assert(min_young_length < max_young_length, 704 "otherwise we should have discovered that max_young_length " 705 "fits into the pause target and not done the binary search"); 706 assert(predict_will_fit(min_young_length, base_time_ms, 707 base_free_regions, target_pause_time_ms), 708 "min_young_length, the result of the binary search, should " 709 "fit into the pause target"); 710 assert(!predict_will_fit(min_young_length + 1, base_time_ms, 711 base_free_regions, target_pause_time_ms), 712 "min_young_length, the result of the binary search, should be " 713 "optimal, so no larger length should fit into the pause target"); 714 } 715 } else { 716 // Even the minimum length doesn't fit into the pause time 717 // target, return it as the result nevertheless. 718 } 719 return base_min_length + min_young_length; 720 } 721 722 double G1CollectorPolicy::predict_survivor_regions_evac_time() const { 723 double survivor_regions_evac_time = 0.0; 724 for (HeapRegion * r = _recorded_survivor_head; 725 r != NULL && r != _recorded_survivor_tail->get_next_young_region(); 726 r = r->get_next_young_region()) { 727 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young()); 728 } 729 return survivor_regions_evac_time; 730 } 731 732 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() { 733 guarantee( adaptive_young_list_length(), "should not call this otherwise" ); 734 735 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths(); 736 if (rs_lengths > _rs_lengths_prediction) { 737 // add 10% to avoid having to recalculate often 738 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; 739 update_rs_lengths_prediction(rs_lengths_prediction); 740 741 update_young_list_max_and_target_length(rs_lengths_prediction); 742 } 743 } 744 745 void G1CollectorPolicy::update_rs_lengths_prediction() { 746 update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq)); 747 } 748 749 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) { 750 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) { 751 _rs_lengths_prediction = prediction; 752 } 753 } 754 755 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size, 756 bool is_tlab, 757 bool* gc_overhead_limit_was_exceeded) { 758 guarantee(false, "Not using this policy feature yet."); 759 return NULL; 760 } 761 762 // This method controls how a collector handles one or more 763 // of its generations being fully allocated. 764 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size, 765 bool is_tlab) { 766 guarantee(false, "Not using this policy feature yet."); 767 return NULL; 768 } 769 770 771 #ifndef PRODUCT 772 bool G1CollectorPolicy::verify_young_ages() { 773 HeapRegion* head = _g1->young_list()->first_region(); 774 return 775 verify_young_ages(head, _short_lived_surv_rate_group); 776 // also call verify_young_ages on any additional surv rate groups 777 } 778 779 bool 780 G1CollectorPolicy::verify_young_ages(HeapRegion* head, 781 SurvRateGroup *surv_rate_group) { 782 guarantee( surv_rate_group != NULL, "pre-condition" ); 783 784 const char* name = surv_rate_group->name(); 785 bool ret = true; 786 int prev_age = -1; 787 788 for (HeapRegion* curr = head; 789 curr != NULL; 790 curr = curr->get_next_young_region()) { 791 SurvRateGroup* group = curr->surv_rate_group(); 792 if (group == NULL && !curr->is_survivor()) { 793 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name); 794 ret = false; 795 } 796 797 if (surv_rate_group == group) { 798 int age = curr->age_in_surv_rate_group(); 799 800 if (age < 0) { 801 gclog_or_tty->print_cr("## %s: encountered negative age", name); 802 ret = false; 803 } 804 805 if (age <= prev_age) { 806 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing " 807 "(%d, %d)", name, age, prev_age); 808 ret = false; 809 } 810 prev_age = age; 811 } 812 } 813 814 return ret; 815 } 816 #endif // PRODUCT 817 818 void G1CollectorPolicy::record_full_collection_start() { 819 _full_collection_start_sec = os::elapsedTime(); 820 record_heap_size_info_at_start(true /* full */); 821 // Release the future to-space so that it is available for compaction into. 822 collector_state()->set_full_collection(true); 823 } 824 825 void G1CollectorPolicy::record_full_collection_end() { 826 // Consider this like a collection pause for the purposes of allocation 827 // since last pause. 828 double end_sec = os::elapsedTime(); 829 double full_gc_time_sec = end_sec - _full_collection_start_sec; 830 double full_gc_time_ms = full_gc_time_sec * 1000.0; 831 832 _trace_old_gen_time_data.record_full_collection(full_gc_time_ms); 833 834 update_recent_gc_times(end_sec, full_gc_time_ms); 835 836 collector_state()->set_full_collection(false); 837 838 // "Nuke" the heuristics that control the young/mixed GC 839 // transitions and make sure we start with young GCs after the Full GC. 840 collector_state()->set_gcs_are_young(true); 841 collector_state()->set_last_young_gc(false); 842 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0)); 843 collector_state()->set_during_initial_mark_pause(false); 844 collector_state()->set_in_marking_window(false); 845 collector_state()->set_in_marking_window_im(false); 846 847 _short_lived_surv_rate_group->start_adding_regions(); 848 // also call this on any additional surv rate groups 849 850 record_survivor_regions(0, NULL, NULL); 851 852 _free_regions_at_end_of_collection = _g1->num_free_regions(); 853 // Reset survivors SurvRateGroup. 854 _survivor_surv_rate_group->reset(); 855 update_young_list_max_and_target_length(); 856 update_rs_lengths_prediction(); 857 _collectionSetChooser->clear(); 858 859 _bytes_allocated_in_old_since_last_gc = 0; 860 861 record_pause(FullGC, _full_collection_start_sec, end_sec); 862 } 863 864 void G1CollectorPolicy::record_stop_world_start() { 865 _stop_world_start = os::elapsedTime(); 866 } 867 868 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) { 869 // We only need to do this here as the policy will only be applied 870 // to the GC we're about to start. so, no point is calculating this 871 // every time we calculate / recalculate the target young length. 872 update_survivors_policy(); 873 874 assert(_g1->used() == _g1->recalculate_used(), 875 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT, 876 _g1->used(), _g1->recalculate_used()); 877 878 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0; 879 _trace_young_gen_time_data.record_start_collection(s_w_t_ms); 880 _stop_world_start = 0.0; 881 882 record_heap_size_info_at_start(false /* full */); 883 884 phase_times()->record_cur_collection_start_sec(start_time_sec); 885 _pending_cards = _g1->pending_card_num(); 886 887 _collection_set_bytes_used_before = 0; 888 _bytes_copied_during_gc = 0; 889 890 collector_state()->set_last_gc_was_young(false); 891 892 // do that for any other surv rate groups 893 _short_lived_surv_rate_group->stop_adding_regions(); 894 _survivors_age_table.clear(); 895 896 assert( verify_young_ages(), "region age verification" ); 897 } 898 899 void G1CollectorPolicy::record_concurrent_mark_init_end(double 900 mark_init_elapsed_time_ms) { 901 collector_state()->set_during_marking(true); 902 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now"); 903 collector_state()->set_during_initial_mark_pause(false); 904 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms; 905 } 906 907 void G1CollectorPolicy::record_concurrent_mark_remark_start() { 908 _mark_remark_start_sec = os::elapsedTime(); 909 collector_state()->set_during_marking(false); 910 } 911 912 void G1CollectorPolicy::record_concurrent_mark_remark_end() { 913 double end_time_sec = os::elapsedTime(); 914 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; 915 _concurrent_mark_remark_times_ms->add(elapsed_time_ms); 916 _cur_mark_stop_world_time_ms += elapsed_time_ms; 917 _prev_collection_pause_end_ms += elapsed_time_ms; 918 919 record_pause(Remark, _mark_remark_start_sec, end_time_sec); 920 } 921 922 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() { 923 _mark_cleanup_start_sec = os::elapsedTime(); 924 } 925 926 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() { 927 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc", 928 "skip last young-only gc"); 929 collector_state()->set_last_young_gc(should_continue_with_reclaim); 930 // We skip the marking phase. 931 if (!should_continue_with_reclaim) { 932 abort_time_to_mixed_tracking(); 933 } 934 collector_state()->set_in_marking_window(false); 935 } 936 937 void G1CollectorPolicy::record_concurrent_pause() { 938 if (_stop_world_start > 0.0) { 939 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0; 940 _trace_young_gen_time_data.record_yield_time(yield_ms); 941 } 942 } 943 944 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const { 945 return phase_times()->average_time_ms(phase); 946 } 947 948 double G1CollectorPolicy::young_other_time_ms() const { 949 return phase_times()->young_cset_choice_time_ms() + 950 phase_times()->young_free_cset_time_ms(); 951 } 952 953 double G1CollectorPolicy::non_young_other_time_ms() const { 954 return phase_times()->non_young_cset_choice_time_ms() + 955 phase_times()->non_young_free_cset_time_ms(); 956 957 } 958 959 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const { 960 return pause_time_ms - 961 average_time_ms(G1GCPhaseTimes::UpdateRS) - 962 average_time_ms(G1GCPhaseTimes::ScanRS) - 963 average_time_ms(G1GCPhaseTimes::ObjCopy) - 964 average_time_ms(G1GCPhaseTimes::Termination); 965 } 966 967 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const { 968 return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms(); 969 } 970 971 bool G1CollectorPolicy::about_to_start_mixed_phase() const { 972 return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc(); 973 } 974 975 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { 976 if (about_to_start_mixed_phase()) { 977 return false; 978 } 979 980 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold(); 981 982 size_t cur_used_bytes = _g1->non_young_capacity_bytes(); 983 size_t alloc_byte_size = alloc_word_size * HeapWordSize; 984 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size; 985 986 if (marking_request_bytes > marking_initiating_used_threshold) { 987 if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) { 988 ergo_verbose5(ErgoConcCycles, 989 "request concurrent cycle initiation", 990 ergo_format_reason("occupancy higher than threshold") 991 ergo_format_byte("occupancy") 992 ergo_format_byte("allocation request") 993 ergo_format_byte_perc("threshold") 994 ergo_format_str("source"), 995 cur_used_bytes, 996 alloc_byte_size, 997 marking_initiating_used_threshold, 998 (double) marking_initiating_used_threshold / _g1->capacity() * 100, 999 source); 1000 return true; 1001 } else { 1002 ergo_verbose5(ErgoConcCycles, 1003 "do not request concurrent cycle initiation", 1004 ergo_format_reason("still doing mixed collections") 1005 ergo_format_byte("occupancy") 1006 ergo_format_byte("allocation request") 1007 ergo_format_byte_perc("threshold") 1008 ergo_format_str("source"), 1009 cur_used_bytes, 1010 alloc_byte_size, 1011 marking_initiating_used_threshold, 1012 (double) InitiatingHeapOccupancyPercent, 1013 source); 1014 } 1015 } 1016 1017 return false; 1018 } 1019 1020 // Anything below that is considered to be zero 1021 #define MIN_TIMER_GRANULARITY 0.0000001 1022 1023 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) { 1024 double end_time_sec = os::elapsedTime(); 1025 1026 size_t cur_used_bytes = _g1->used(); 1027 assert(cur_used_bytes == _g1->recalculate_used(), "It should!"); 1028 bool last_pause_included_initial_mark = false; 1029 bool update_stats = !_g1->evacuation_failed(); 1030 1031 #ifndef PRODUCT 1032 if (G1YoungSurvRateVerbose) { 1033 gclog_or_tty->cr(); 1034 _short_lived_surv_rate_group->print(); 1035 // do that for any other surv rate groups too 1036 } 1037 #endif // PRODUCT 1038 1039 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec); 1040 1041 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause(); 1042 if (last_pause_included_initial_mark) { 1043 record_concurrent_mark_init_end(0.0); 1044 } else { 1045 maybe_start_marking(); 1046 } 1047 1048 double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms); 1049 if (app_time_ms < MIN_TIMER_GRANULARITY) { 1050 // This usually happens due to the timer not having the required 1051 // granularity. Some Linuxes are the usual culprits. 1052 // We'll just set it to something (arbitrarily) small. 1053 app_time_ms = 1.0; 1054 } 1055 1056 if (update_stats) { 1057 _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times()); 1058 // We maintain the invariant that all objects allocated by mutator 1059 // threads will be allocated out of eden regions. So, we can use 1060 // the eden region number allocated since the previous GC to 1061 // calculate the application's allocate rate. The only exception 1062 // to that is humongous objects that are allocated separately. But 1063 // given that humongous object allocations do not really affect 1064 // either the pause's duration nor when the next pause will take 1065 // place we can safely ignore them here. 1066 uint regions_allocated = eden_cset_region_length(); 1067 double alloc_rate_ms = (double) regions_allocated / app_time_ms; 1068 _alloc_rate_ms_seq->add(alloc_rate_ms); 1069 1070 double interval_ms = 1071 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0; 1072 update_recent_gc_times(end_time_sec, pause_time_ms); 1073 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms; 1074 if (recent_avg_pause_time_ratio() < 0.0 || 1075 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) { 1076 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in 1077 // CR 6902692 by redoing the manner in which the ratio is incrementally computed. 1078 if (_recent_avg_pause_time_ratio < 0.0) { 1079 _recent_avg_pause_time_ratio = 0.0; 1080 } else { 1081 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant"); 1082 _recent_avg_pause_time_ratio = 1.0; 1083 } 1084 } 1085 } 1086 1087 bool new_in_marking_window = collector_state()->in_marking_window(); 1088 bool new_in_marking_window_im = false; 1089 if (last_pause_included_initial_mark) { 1090 new_in_marking_window = true; 1091 new_in_marking_window_im = true; 1092 } 1093 1094 if (collector_state()->last_young_gc()) { 1095 // This is supposed to to be the "last young GC" before we start 1096 // doing mixed GCs. Here we decide whether to start mixed GCs or not. 1097 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC"); 1098 1099 if (next_gc_should_be_mixed("start mixed GCs", 1100 "do not start mixed GCs")) { 1101 collector_state()->set_gcs_are_young(false); 1102 } else { 1103 // We aborted the mixed GC phase early. 1104 abort_time_to_mixed_tracking(); 1105 } 1106 1107 collector_state()->set_last_young_gc(false); 1108 } 1109 1110 if (!collector_state()->last_gc_was_young()) { 1111 // This is a mixed GC. Here we decide whether to continue doing 1112 // mixed GCs or not. 1113 if (!next_gc_should_be_mixed("continue mixed GCs", 1114 "do not continue mixed GCs")) { 1115 collector_state()->set_gcs_are_young(true); 1116 1117 maybe_start_marking(); 1118 } 1119 } 1120 1121 _short_lived_surv_rate_group->start_adding_regions(); 1122 // Do that for any other surv rate groups 1123 1124 if (update_stats) { 1125 double cost_per_card_ms = 0.0; 1126 double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC); 1127 if (_pending_cards > 0) { 1128 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards; 1129 _cost_per_card_ms_seq->add(cost_per_card_ms); 1130 } 1131 _cost_scan_hcc_seq->add(cost_scan_hcc); 1132 1133 double cost_per_entry_ms = 0.0; 1134 if (cards_scanned > 10) { 1135 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned; 1136 if (collector_state()->last_gc_was_young()) { 1137 _cost_per_entry_ms_seq->add(cost_per_entry_ms); 1138 } else { 1139 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms); 1140 } 1141 } 1142 1143 if (_max_rs_lengths > 0) { 1144 double cards_per_entry_ratio = 1145 (double) cards_scanned / (double) _max_rs_lengths; 1146 if (collector_state()->last_gc_was_young()) { 1147 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1148 } else { 1149 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1150 } 1151 } 1152 1153 // This is defensive. For a while _max_rs_lengths could get 1154 // smaller than _recorded_rs_lengths which was causing 1155 // rs_length_diff to get very large and mess up the RSet length 1156 // predictions. The reason was unsafe concurrent updates to the 1157 // _inc_cset_recorded_rs_lengths field which the code below guards 1158 // against (see CR 7118202). This bug has now been fixed (see CR 1159 // 7119027). However, I'm still worried that 1160 // _inc_cset_recorded_rs_lengths might still end up somewhat 1161 // inaccurate. The concurrent refinement thread calculates an 1162 // RSet's length concurrently with other CR threads updating it 1163 // which might cause it to calculate the length incorrectly (if, 1164 // say, it's in mid-coarsening). So I'll leave in the defensive 1165 // conditional below just in case. 1166 size_t rs_length_diff = 0; 1167 if (_max_rs_lengths > _recorded_rs_lengths) { 1168 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths; 1169 } 1170 _rs_length_diff_seq->add((double) rs_length_diff); 1171 1172 size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes; 1173 size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes; 1174 double cost_per_byte_ms = 0.0; 1175 1176 if (copied_bytes > 0) { 1177 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes; 1178 if (collector_state()->in_marking_window()) { 1179 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms); 1180 } else { 1181 _cost_per_byte_ms_seq->add(cost_per_byte_ms); 1182 } 1183 } 1184 1185 if (young_cset_region_length() > 0) { 1186 _young_other_cost_per_region_ms_seq->add(young_other_time_ms() / 1187 young_cset_region_length()); 1188 } 1189 1190 if (old_cset_region_length() > 0) { 1191 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() / 1192 old_cset_region_length()); 1193 } 1194 1195 _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms)); 1196 1197 _pending_cards_seq->add((double) _pending_cards); 1198 _rs_lengths_seq->add((double) _max_rs_lengths); 1199 } 1200 1201 collector_state()->set_in_marking_window(new_in_marking_window); 1202 collector_state()->set_in_marking_window_im(new_in_marking_window_im); 1203 _free_regions_at_end_of_collection = _g1->num_free_regions(); 1204 // IHOP control wants to know the expected young gen length if it were not 1205 // restrained by the heap reserve. Using the actual length would make the 1206 // prediction too small and the limit the young gen every time we get to the 1207 // predicted target occupancy. 1208 size_t last_unrestrained_young_length = update_young_list_max_and_target_length(); 1209 update_rs_lengths_prediction(); 1210 1211 update_ihop_prediction(app_time_ms / 1000.0, 1212 _bytes_allocated_in_old_since_last_gc, 1213 last_unrestrained_young_length * HeapRegion::GrainBytes); 1214 _bytes_allocated_in_old_since_last_gc = 0; 1215 1216 _ihop_control->send_trace_event(_g1->gc_tracer_stw()); 1217 1218 // Note that _mmu_tracker->max_gc_time() returns the time in seconds. 1219 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; 1220 1221 double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC); 1222 1223 if (update_rs_time_goal_ms < scan_hcc_time_ms) { 1224 ergo_verbose2(ErgoTiming, 1225 "adjust concurrent refinement thresholds", 1226 ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal") 1227 ergo_format_ms("Update RS time goal") 1228 ergo_format_ms("Scan HCC time"), 1229 update_rs_time_goal_ms, 1230 scan_hcc_time_ms); 1231 1232 update_rs_time_goal_ms = 0; 1233 } else { 1234 update_rs_time_goal_ms -= scan_hcc_time_ms; 1235 } 1236 adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms, 1237 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS), 1238 update_rs_time_goal_ms); 1239 1240 _collectionSetChooser->verify(); 1241 } 1242 1243 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const { 1244 if (G1UseAdaptiveIHOP) { 1245 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent, 1246 G1CollectedHeap::heap()->max_capacity(), 1247 &_predictor, 1248 G1ReservePercent, 1249 G1HeapWastePercent); 1250 } else { 1251 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent, 1252 G1CollectedHeap::heap()->max_capacity()); 1253 } 1254 } 1255 1256 void G1CollectorPolicy::update_ihop_prediction(double mutator_time_s, 1257 size_t mutator_alloc_bytes, 1258 size_t young_gen_size) { 1259 // Always try to update IHOP prediction. Even evacuation failures give information 1260 // about e.g. whether to start IHOP earlier next time. 1261 1262 // Avoid using really small application times that might create samples with 1263 // very high or very low values. They may be caused by e.g. back-to-back gcs. 1264 double const min_valid_time = 1e-6; 1265 1266 bool report = false; 1267 1268 double marking_to_mixed_time = -1.0; 1269 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) { 1270 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time(); 1271 assert(marking_to_mixed_time > 0.0, 1272 "Initial mark to mixed time must be larger than zero but is %.3f", 1273 marking_to_mixed_time); 1274 if (marking_to_mixed_time > min_valid_time) { 1275 _ihop_control->update_marking_length(marking_to_mixed_time); 1276 report = true; 1277 } 1278 } 1279 1280 // As an approximation for the young gc promotion rates during marking we use 1281 // all of them. In many applications there are only a few if any young gcs during 1282 // marking, which makes any prediction useless. This increases the accuracy of the 1283 // prediction. 1284 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) { 1285 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size); 1286 report = true; 1287 } 1288 1289 if (report) { 1290 report_ihop_statistics(); 1291 } 1292 } 1293 1294 void G1CollectorPolicy::report_ihop_statistics() { 1295 _ihop_control->print(); 1296 } 1297 1298 #define EXT_SIZE_FORMAT "%.1f%s" 1299 #define EXT_SIZE_PARAMS(bytes) \ 1300 byte_size_in_proper_unit((double)(bytes)), \ 1301 proper_unit_for_byte_size((bytes)) 1302 1303 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) { 1304 YoungList* young_list = _g1->young_list(); 1305 _eden_used_bytes_before_gc = young_list->eden_used_bytes(); 1306 _survivor_used_bytes_before_gc = young_list->survivor_used_bytes(); 1307 _heap_capacity_bytes_before_gc = _g1->capacity(); 1308 _heap_used_bytes_before_gc = _g1->used(); 1309 1310 _eden_capacity_bytes_before_gc = 1311 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc; 1312 1313 if (full) { 1314 _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes(); 1315 } 1316 } 1317 1318 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const { 1319 size_t bytes_after = _g1->used(); 1320 size_t capacity = _g1->capacity(); 1321 1322 gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)", 1323 byte_size_in_proper_unit(bytes_before), 1324 proper_unit_for_byte_size(bytes_before), 1325 byte_size_in_proper_unit(bytes_after), 1326 proper_unit_for_byte_size(bytes_after), 1327 byte_size_in_proper_unit(capacity), 1328 proper_unit_for_byte_size(capacity)); 1329 } 1330 1331 void G1CollectorPolicy::print_heap_transition() const { 1332 print_heap_transition(_heap_used_bytes_before_gc); 1333 } 1334 1335 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const { 1336 YoungList* young_list = _g1->young_list(); 1337 1338 size_t eden_used_bytes_after_gc = young_list->eden_used_bytes(); 1339 size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes(); 1340 size_t heap_used_bytes_after_gc = _g1->used(); 1341 1342 size_t heap_capacity_bytes_after_gc = _g1->capacity(); 1343 size_t eden_capacity_bytes_after_gc = 1344 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc; 1345 1346 gclog_or_tty->print( 1347 " [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") " 1348 "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " " 1349 "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" 1350 EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]", 1351 EXT_SIZE_PARAMS(_eden_used_bytes_before_gc), 1352 EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc), 1353 EXT_SIZE_PARAMS(eden_used_bytes_after_gc), 1354 EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc), 1355 EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc), 1356 EXT_SIZE_PARAMS(survivor_used_bytes_after_gc), 1357 EXT_SIZE_PARAMS(_heap_used_bytes_before_gc), 1358 EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc), 1359 EXT_SIZE_PARAMS(heap_used_bytes_after_gc), 1360 EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc)); 1361 1362 if (full) { 1363 MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc); 1364 } 1365 1366 gclog_or_tty->cr(); 1367 } 1368 1369 void G1CollectorPolicy::print_phases(double pause_time_sec) { 1370 phase_times()->print(pause_time_sec); 1371 } 1372 1373 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time, 1374 double update_rs_processed_buffers, 1375 double goal_ms) { 1376 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1377 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine(); 1378 1379 if (G1UseAdaptiveConcRefinement) { 1380 const int k_gy = 3, k_gr = 6; 1381 const double inc_k = 1.1, dec_k = 0.9; 1382 1383 int g = cg1r->green_zone(); 1384 if (update_rs_time > goal_ms) { 1385 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing. 1386 } else { 1387 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) { 1388 g = (int)MAX2(g * inc_k, g + 1.0); 1389 } 1390 } 1391 // Change the refinement threads params 1392 cg1r->set_green_zone(g); 1393 cg1r->set_yellow_zone(g * k_gy); 1394 cg1r->set_red_zone(g * k_gr); 1395 cg1r->reinitialize_threads(); 1396 1397 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1); 1398 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta, 1399 cg1r->yellow_zone()); 1400 // Change the barrier params 1401 dcqs.set_process_completed_threshold(processing_threshold); 1402 dcqs.set_max_completed_queue(cg1r->red_zone()); 1403 } 1404 1405 int curr_queue_size = dcqs.completed_buffers_num(); 1406 if (curr_queue_size >= cg1r->yellow_zone()) { 1407 dcqs.set_completed_queue_padding(curr_queue_size); 1408 } else { 1409 dcqs.set_completed_queue_padding(0); 1410 } 1411 dcqs.notify_if_necessary(); 1412 } 1413 1414 size_t G1CollectorPolicy::predict_rs_length_diff() const { 1415 return (size_t) get_new_prediction(_rs_length_diff_seq); 1416 } 1417 1418 double G1CollectorPolicy::predict_alloc_rate_ms() const { 1419 return get_new_prediction(_alloc_rate_ms_seq); 1420 } 1421 1422 double G1CollectorPolicy::predict_cost_per_card_ms() const { 1423 return get_new_prediction(_cost_per_card_ms_seq); 1424 } 1425 1426 double G1CollectorPolicy::predict_scan_hcc_ms() const { 1427 return get_new_prediction(_cost_scan_hcc_seq); 1428 } 1429 1430 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const { 1431 return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms(); 1432 } 1433 1434 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const { 1435 return get_new_prediction(_young_cards_per_entry_ratio_seq); 1436 } 1437 1438 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const { 1439 if (_mixed_cards_per_entry_ratio_seq->num() < 2) { 1440 return predict_young_cards_per_entry_ratio(); 1441 } else { 1442 return get_new_prediction(_mixed_cards_per_entry_ratio_seq); 1443 } 1444 } 1445 1446 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const { 1447 return (size_t) (rs_length * predict_young_cards_per_entry_ratio()); 1448 } 1449 1450 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const { 1451 return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio()); 1452 } 1453 1454 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const { 1455 if (collector_state()->gcs_are_young()) { 1456 return card_num * get_new_prediction(_cost_per_entry_ms_seq); 1457 } else { 1458 return predict_mixed_rs_scan_time_ms(card_num); 1459 } 1460 } 1461 1462 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const { 1463 if (_mixed_cost_per_entry_ms_seq->num() < 3) { 1464 return card_num * get_new_prediction(_cost_per_entry_ms_seq); 1465 } else { 1466 return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq); 1467 } 1468 } 1469 1470 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const { 1471 if (_cost_per_byte_ms_during_cm_seq->num() < 3) { 1472 return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq); 1473 } else { 1474 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq); 1475 } 1476 } 1477 1478 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const { 1479 if (collector_state()->during_concurrent_mark()) { 1480 return predict_object_copy_time_ms_during_cm(bytes_to_copy); 1481 } else { 1482 return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq); 1483 } 1484 } 1485 1486 double G1CollectorPolicy::predict_constant_other_time_ms() const { 1487 return get_new_prediction(_constant_other_time_ms_seq); 1488 } 1489 1490 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const { 1491 return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq); 1492 } 1493 1494 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const { 1495 return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq); 1496 } 1497 1498 double G1CollectorPolicy::predict_remark_time_ms() const { 1499 return get_new_prediction(_concurrent_mark_remark_times_ms); 1500 } 1501 1502 double G1CollectorPolicy::predict_cleanup_time_ms() const { 1503 return get_new_prediction(_concurrent_mark_cleanup_times_ms); 1504 } 1505 1506 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const { 1507 TruncatedSeq* seq = surv_rate_group->get_seq(age); 1508 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age); 1509 double pred = get_new_prediction(seq); 1510 if (pred > 1.0) { 1511 pred = 1.0; 1512 } 1513 return pred; 1514 } 1515 1516 double G1CollectorPolicy::predict_yg_surv_rate(int age) const { 1517 return predict_yg_surv_rate(age, _short_lived_surv_rate_group); 1518 } 1519 1520 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const { 1521 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); 1522 } 1523 1524 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards, 1525 size_t scanned_cards) const { 1526 return 1527 predict_rs_update_time_ms(pending_cards) + 1528 predict_rs_scan_time_ms(scanned_cards) + 1529 predict_constant_other_time_ms(); 1530 } 1531 1532 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const { 1533 size_t rs_length = predict_rs_length_diff(); 1534 size_t card_num; 1535 if (collector_state()->gcs_are_young()) { 1536 card_num = predict_young_card_num(rs_length); 1537 } else { 1538 card_num = predict_non_young_card_num(rs_length); 1539 } 1540 return predict_base_elapsed_time_ms(pending_cards, card_num); 1541 } 1542 1543 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const { 1544 size_t bytes_to_copy; 1545 if (hr->is_marked()) 1546 bytes_to_copy = hr->max_live_bytes(); 1547 else { 1548 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant"); 1549 int age = hr->age_in_surv_rate_group(); 1550 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); 1551 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate); 1552 } 1553 return bytes_to_copy; 1554 } 1555 1556 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr, 1557 bool for_young_gc) const { 1558 size_t rs_length = hr->rem_set()->occupied(); 1559 size_t card_num; 1560 1561 // Predicting the number of cards is based on which type of GC 1562 // we're predicting for. 1563 if (for_young_gc) { 1564 card_num = predict_young_card_num(rs_length); 1565 } else { 1566 card_num = predict_non_young_card_num(rs_length); 1567 } 1568 size_t bytes_to_copy = predict_bytes_to_copy(hr); 1569 1570 double region_elapsed_time_ms = 1571 predict_rs_scan_time_ms(card_num) + 1572 predict_object_copy_time_ms(bytes_to_copy); 1573 1574 // The prediction of the "other" time for this region is based 1575 // upon the region type and NOT the GC type. 1576 if (hr->is_young()) { 1577 region_elapsed_time_ms += predict_young_other_time_ms(1); 1578 } else { 1579 region_elapsed_time_ms += predict_non_young_other_time_ms(1); 1580 } 1581 return region_elapsed_time_ms; 1582 } 1583 1584 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length, 1585 uint survivor_cset_region_length) { 1586 _eden_cset_region_length = eden_cset_region_length; 1587 _survivor_cset_region_length = survivor_cset_region_length; 1588 _old_cset_region_length = 0; 1589 } 1590 1591 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) { 1592 _recorded_rs_lengths = rs_lengths; 1593 } 1594 1595 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec, 1596 double elapsed_ms) { 1597 _recent_gc_times_ms->add(elapsed_ms); 1598 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec); 1599 _prev_collection_pause_end_ms = end_time_sec * 1000.0; 1600 } 1601 1602 size_t G1CollectorPolicy::expansion_amount() const { 1603 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0; 1604 double threshold = _gc_overhead_perc; 1605 if (recent_gc_overhead > threshold) { 1606 // We will double the existing space, or take 1607 // G1ExpandByPercentOfAvailable % of the available expansion 1608 // space, whichever is smaller, bounded below by a minimum 1609 // expansion (unless that's all that's left.) 1610 const size_t min_expand_bytes = 1*M; 1611 size_t reserved_bytes = _g1->max_capacity(); 1612 size_t committed_bytes = _g1->capacity(); 1613 size_t uncommitted_bytes = reserved_bytes - committed_bytes; 1614 size_t expand_bytes; 1615 size_t expand_bytes_via_pct = 1616 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100; 1617 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes); 1618 expand_bytes = MAX2(expand_bytes, min_expand_bytes); 1619 expand_bytes = MIN2(expand_bytes, uncommitted_bytes); 1620 1621 ergo_verbose5(ErgoHeapSizing, 1622 "attempt heap expansion", 1623 ergo_format_reason("recent GC overhead higher than " 1624 "threshold after GC") 1625 ergo_format_perc("recent GC overhead") 1626 ergo_format_perc("threshold") 1627 ergo_format_byte("uncommitted") 1628 ergo_format_byte_perc("calculated expansion amount"), 1629 recent_gc_overhead, threshold, 1630 uncommitted_bytes, 1631 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable); 1632 1633 return expand_bytes; 1634 } else { 1635 return 0; 1636 } 1637 } 1638 1639 void G1CollectorPolicy::print_tracing_info() const { 1640 _trace_young_gen_time_data.print(); 1641 _trace_old_gen_time_data.print(); 1642 } 1643 1644 void G1CollectorPolicy::print_yg_surv_rate_info() const { 1645 #ifndef PRODUCT 1646 _short_lived_surv_rate_group->print_surv_rate_summary(); 1647 // add this call for any other surv rate groups 1648 #endif // PRODUCT 1649 } 1650 1651 bool G1CollectorPolicy::is_young_list_full() const { 1652 uint young_list_length = _g1->young_list()->length(); 1653 uint young_list_target_length = _young_list_target_length; 1654 return young_list_length >= young_list_target_length; 1655 } 1656 1657 bool G1CollectorPolicy::can_expand_young_list() const { 1658 uint young_list_length = _g1->young_list()->length(); 1659 uint young_list_max_length = _young_list_max_length; 1660 return young_list_length < young_list_max_length; 1661 } 1662 1663 void G1CollectorPolicy::update_max_gc_locker_expansion() { 1664 uint expansion_region_num = 0; 1665 if (GCLockerEdenExpansionPercent > 0) { 1666 double perc = (double) GCLockerEdenExpansionPercent / 100.0; 1667 double expansion_region_num_d = perc * (double) _young_list_target_length; 1668 // We use ceiling so that if expansion_region_num_d is > 0.0 (but 1669 // less than 1.0) we'll get 1. 1670 expansion_region_num = (uint) ceil(expansion_region_num_d); 1671 } else { 1672 assert(expansion_region_num == 0, "sanity"); 1673 } 1674 _young_list_max_length = _young_list_target_length + expansion_region_num; 1675 assert(_young_list_target_length <= _young_list_max_length, "post-condition"); 1676 } 1677 1678 // Calculates survivor space parameters. 1679 void G1CollectorPolicy::update_survivors_policy() { 1680 double max_survivor_regions_d = 1681 (double) _young_list_target_length / (double) SurvivorRatio; 1682 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but 1683 // smaller than 1.0) we'll get 1. 1684 _max_survivor_regions = (uint) ceil(max_survivor_regions_d); 1685 1686 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold( 1687 HeapRegion::GrainWords * _max_survivor_regions, counters()); 1688 } 1689 1690 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) { 1691 // We actually check whether we are marking here and not if we are in a 1692 // reclamation phase. This means that we will schedule a concurrent mark 1693 // even while we are still in the process of reclaiming memory. 1694 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1695 if (!during_cycle) { 1696 ergo_verbose1(ErgoConcCycles, 1697 "request concurrent cycle initiation", 1698 ergo_format_reason("requested by GC cause") 1699 ergo_format_str("GC cause"), 1700 GCCause::to_string(gc_cause)); 1701 collector_state()->set_initiate_conc_mark_if_possible(true); 1702 return true; 1703 } else { 1704 ergo_verbose1(ErgoConcCycles, 1705 "do not request concurrent cycle initiation", 1706 ergo_format_reason("concurrent cycle already in progress") 1707 ergo_format_str("GC cause"), 1708 GCCause::to_string(gc_cause)); 1709 return false; 1710 } 1711 } 1712 1713 void G1CollectorPolicy::initiate_conc_mark() { 1714 collector_state()->set_during_initial_mark_pause(true); 1715 collector_state()->set_initiate_conc_mark_if_possible(false); 1716 } 1717 1718 void G1CollectorPolicy::decide_on_conc_mark_initiation() { 1719 // We are about to decide on whether this pause will be an 1720 // initial-mark pause. 1721 1722 // First, collector_state()->during_initial_mark_pause() should not be already set. We 1723 // will set it here if we have to. However, it should be cleared by 1724 // the end of the pause (it's only set for the duration of an 1725 // initial-mark pause). 1726 assert(!collector_state()->during_initial_mark_pause(), "pre-condition"); 1727 1728 if (collector_state()->initiate_conc_mark_if_possible()) { 1729 // We had noticed on a previous pause that the heap occupancy has 1730 // gone over the initiating threshold and we should start a 1731 // concurrent marking cycle. So we might initiate one. 1732 1733 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) { 1734 // Initiate a new initial mark if there is no marking or reclamation going on. 1735 initiate_conc_mark(); 1736 ergo_verbose0(ErgoConcCycles, 1737 "initiate concurrent cycle", 1738 ergo_format_reason("concurrent cycle initiation requested")); 1739 } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) { 1740 // Initiate a user requested initial mark. An initial mark must be young only 1741 // GC, so the collector state must be updated to reflect this. 1742 collector_state()->set_gcs_are_young(true); 1743 collector_state()->set_last_young_gc(false); 1744 1745 initiate_conc_mark(); 1746 ergo_verbose0(ErgoConcCycles, 1747 "initiate concurrent cycle", 1748 ergo_format_reason("user requested concurrent cycle")); 1749 } else { 1750 // The concurrent marking thread is still finishing up the 1751 // previous cycle. If we start one right now the two cycles 1752 // overlap. In particular, the concurrent marking thread might 1753 // be in the process of clearing the next marking bitmap (which 1754 // we will use for the next cycle if we start one). Starting a 1755 // cycle now will be bad given that parts of the marking 1756 // information might get cleared by the marking thread. And we 1757 // cannot wait for the marking thread to finish the cycle as it 1758 // periodically yields while clearing the next marking bitmap 1759 // and, if it's in a yield point, it's waiting for us to 1760 // finish. So, at this point we will not start a cycle and we'll 1761 // let the concurrent marking thread complete the last one. 1762 ergo_verbose0(ErgoConcCycles, 1763 "do not initiate concurrent cycle", 1764 ergo_format_reason("concurrent cycle already in progress")); 1765 } 1766 } 1767 } 1768 1769 class ParKnownGarbageHRClosure: public HeapRegionClosure { 1770 G1CollectedHeap* _g1h; 1771 CSetChooserParUpdater _cset_updater; 1772 1773 public: 1774 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted, 1775 uint chunk_size) : 1776 _g1h(G1CollectedHeap::heap()), 1777 _cset_updater(hrSorted, true /* parallel */, chunk_size) { } 1778 1779 bool doHeapRegion(HeapRegion* r) { 1780 // Do we have any marking information for this region? 1781 if (r->is_marked()) { 1782 // We will skip any region that's currently used as an old GC 1783 // alloc region (we should not consider those for collection 1784 // before we fill them up). 1785 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1786 _cset_updater.add_region(r); 1787 } 1788 } 1789 return false; 1790 } 1791 }; 1792 1793 class ParKnownGarbageTask: public AbstractGangTask { 1794 CollectionSetChooser* _hrSorted; 1795 uint _chunk_size; 1796 G1CollectedHeap* _g1; 1797 HeapRegionClaimer _hrclaimer; 1798 1799 public: 1800 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) : 1801 AbstractGangTask("ParKnownGarbageTask"), 1802 _hrSorted(hrSorted), _chunk_size(chunk_size), 1803 _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {} 1804 1805 void work(uint worker_id) { 1806 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size); 1807 _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer); 1808 } 1809 }; 1810 1811 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const { 1812 assert(n_workers > 0, "Active gc workers should be greater than 0"); 1813 const uint overpartition_factor = 4; 1814 const uint min_chunk_size = MAX2(n_regions / n_workers, 1U); 1815 return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size); 1816 } 1817 1818 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() { 1819 _collectionSetChooser->clear(); 1820 1821 WorkGang* workers = _g1->workers(); 1822 uint n_workers = workers->active_workers(); 1823 1824 uint n_regions = _g1->num_regions(); 1825 uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions); 1826 _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size); 1827 ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers); 1828 workers->run_task(&par_known_garbage_task); 1829 1830 _collectionSetChooser->sort_regions(); 1831 1832 double end_sec = os::elapsedTime(); 1833 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; 1834 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms); 1835 _cur_mark_stop_world_time_ms += elapsed_time_ms; 1836 _prev_collection_pause_end_ms += elapsed_time_ms; 1837 1838 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec); 1839 } 1840 1841 // Add the heap region at the head of the non-incremental collection set 1842 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) { 1843 assert(_inc_cset_build_state == Active, "Precondition"); 1844 assert(hr->is_old(), "the region should be old"); 1845 1846 assert(!hr->in_collection_set(), "should not already be in the CSet"); 1847 _g1->register_old_region_with_cset(hr); 1848 hr->set_next_in_collection_set(_collection_set); 1849 _collection_set = hr; 1850 _collection_set_bytes_used_before += hr->used(); 1851 size_t rs_length = hr->rem_set()->occupied(); 1852 _recorded_rs_lengths += rs_length; 1853 _old_cset_region_length += 1; 1854 } 1855 1856 // Initialize the per-collection-set information 1857 void G1CollectorPolicy::start_incremental_cset_building() { 1858 assert(_inc_cset_build_state == Inactive, "Precondition"); 1859 1860 _inc_cset_head = NULL; 1861 _inc_cset_tail = NULL; 1862 _inc_cset_bytes_used_before = 0; 1863 1864 _inc_cset_max_finger = 0; 1865 _inc_cset_recorded_rs_lengths = 0; 1866 _inc_cset_recorded_rs_lengths_diffs = 0; 1867 _inc_cset_predicted_elapsed_time_ms = 0.0; 1868 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1869 _inc_cset_build_state = Active; 1870 } 1871 1872 void G1CollectorPolicy::finalize_incremental_cset_building() { 1873 assert(_inc_cset_build_state == Active, "Precondition"); 1874 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 1875 1876 // The two "main" fields, _inc_cset_recorded_rs_lengths and 1877 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread 1878 // that adds a new region to the CSet. Further updates by the 1879 // concurrent refinement thread that samples the young RSet lengths 1880 // are accumulated in the *_diffs fields. Here we add the diffs to 1881 // the "main" fields. 1882 1883 if (_inc_cset_recorded_rs_lengths_diffs >= 0) { 1884 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs; 1885 } else { 1886 // This is defensive. The diff should in theory be always positive 1887 // as RSets can only grow between GCs. However, given that we 1888 // sample their size concurrently with other threads updating them 1889 // it's possible that we might get the wrong size back, which 1890 // could make the calculations somewhat inaccurate. 1891 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs); 1892 if (_inc_cset_recorded_rs_lengths >= diffs) { 1893 _inc_cset_recorded_rs_lengths -= diffs; 1894 } else { 1895 _inc_cset_recorded_rs_lengths = 0; 1896 } 1897 } 1898 _inc_cset_predicted_elapsed_time_ms += 1899 _inc_cset_predicted_elapsed_time_ms_diffs; 1900 1901 _inc_cset_recorded_rs_lengths_diffs = 0; 1902 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1903 } 1904 1905 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) { 1906 // This routine is used when: 1907 // * adding survivor regions to the incremental cset at the end of an 1908 // evacuation pause, 1909 // * adding the current allocation region to the incremental cset 1910 // when it is retired, and 1911 // * updating existing policy information for a region in the 1912 // incremental cset via young list RSet sampling. 1913 // Therefore this routine may be called at a safepoint by the 1914 // VM thread, or in-between safepoints by mutator threads (when 1915 // retiring the current allocation region) or a concurrent 1916 // refine thread (RSet sampling). 1917 1918 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 1919 size_t used_bytes = hr->used(); 1920 _inc_cset_recorded_rs_lengths += rs_length; 1921 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms; 1922 _inc_cset_bytes_used_before += used_bytes; 1923 1924 // Cache the values we have added to the aggregated information 1925 // in the heap region in case we have to remove this region from 1926 // the incremental collection set, or it is updated by the 1927 // rset sampling code 1928 hr->set_recorded_rs_length(rs_length); 1929 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms); 1930 } 1931 1932 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, 1933 size_t new_rs_length) { 1934 // Update the CSet information that is dependent on the new RS length 1935 assert(hr->is_young(), "Precondition"); 1936 assert(!SafepointSynchronize::is_at_safepoint(), 1937 "should not be at a safepoint"); 1938 1939 // We could have updated _inc_cset_recorded_rs_lengths and 1940 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do 1941 // that atomically, as this code is executed by a concurrent 1942 // refinement thread, potentially concurrently with a mutator thread 1943 // allocating a new region and also updating the same fields. To 1944 // avoid the atomic operations we accumulate these updates on two 1945 // separate fields (*_diffs) and we'll just add them to the "main" 1946 // fields at the start of a GC. 1947 1948 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length(); 1949 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length; 1950 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff; 1951 1952 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms(); 1953 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 1954 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms; 1955 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff; 1956 1957 hr->set_recorded_rs_length(new_rs_length); 1958 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms); 1959 } 1960 1961 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) { 1962 assert(hr->is_young(), "invariant"); 1963 assert(hr->young_index_in_cset() > -1, "should have already been set"); 1964 assert(_inc_cset_build_state == Active, "Precondition"); 1965 1966 // We need to clear and set the cached recorded/cached collection set 1967 // information in the heap region here (before the region gets added 1968 // to the collection set). An individual heap region's cached values 1969 // are calculated, aggregated with the policy collection set info, 1970 // and cached in the heap region here (initially) and (subsequently) 1971 // by the Young List sampling code. 1972 1973 size_t rs_length = hr->rem_set()->occupied(); 1974 add_to_incremental_cset_info(hr, rs_length); 1975 1976 HeapWord* hr_end = hr->end(); 1977 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end); 1978 1979 assert(!hr->in_collection_set(), "invariant"); 1980 _g1->register_young_region_with_cset(hr); 1981 assert(hr->next_in_collection_set() == NULL, "invariant"); 1982 } 1983 1984 // Add the region at the RHS of the incremental cset 1985 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) { 1986 // We should only ever be appending survivors at the end of a pause 1987 assert(hr->is_survivor(), "Logic"); 1988 1989 // Do the 'common' stuff 1990 add_region_to_incremental_cset_common(hr); 1991 1992 // Now add the region at the right hand side 1993 if (_inc_cset_tail == NULL) { 1994 assert(_inc_cset_head == NULL, "invariant"); 1995 _inc_cset_head = hr; 1996 } else { 1997 _inc_cset_tail->set_next_in_collection_set(hr); 1998 } 1999 _inc_cset_tail = hr; 2000 } 2001 2002 // Add the region to the LHS of the incremental cset 2003 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) { 2004 // Survivors should be added to the RHS at the end of a pause 2005 assert(hr->is_eden(), "Logic"); 2006 2007 // Do the 'common' stuff 2008 add_region_to_incremental_cset_common(hr); 2009 2010 // Add the region at the left hand side 2011 hr->set_next_in_collection_set(_inc_cset_head); 2012 if (_inc_cset_head == NULL) { 2013 assert(_inc_cset_tail == NULL, "Invariant"); 2014 _inc_cset_tail = hr; 2015 } 2016 _inc_cset_head = hr; 2017 } 2018 2019 #ifndef PRODUCT 2020 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) { 2021 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be"); 2022 2023 st->print_cr("\nCollection_set:"); 2024 HeapRegion* csr = list_head; 2025 while (csr != NULL) { 2026 HeapRegion* next = csr->next_in_collection_set(); 2027 assert(csr->in_collection_set(), "bad CS"); 2028 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d", 2029 HR_FORMAT_PARAMS(csr), 2030 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()), 2031 csr->age_in_surv_rate_group_cond()); 2032 csr = next; 2033 } 2034 } 2035 #endif // !PRODUCT 2036 2037 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const { 2038 // Returns the given amount of reclaimable bytes (that represents 2039 // the amount of reclaimable space still to be collected) as a 2040 // percentage of the current heap capacity. 2041 size_t capacity_bytes = _g1->capacity(); 2042 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes; 2043 } 2044 2045 void G1CollectorPolicy::maybe_start_marking() { 2046 if (need_to_start_conc_mark("end of GC")) { 2047 // Note: this might have already been set, if during the last 2048 // pause we decided to start a cycle but at the beginning of 2049 // this pause we decided to postpone it. That's OK. 2050 collector_state()->set_initiate_conc_mark_if_possible(true); 2051 } 2052 } 2053 2054 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const { 2055 assert(!collector_state()->full_collection(), "must be"); 2056 if (collector_state()->during_initial_mark_pause()) { 2057 assert(collector_state()->last_gc_was_young(), "must be"); 2058 assert(!collector_state()->last_young_gc(), "must be"); 2059 return InitialMarkGC; 2060 } else if (collector_state()->last_young_gc()) { 2061 assert(!collector_state()->during_initial_mark_pause(), "must be"); 2062 assert(collector_state()->last_gc_was_young(), "must be"); 2063 return LastYoungGC; 2064 } else if (!collector_state()->last_gc_was_young()) { 2065 assert(!collector_state()->during_initial_mark_pause(), "must be"); 2066 assert(!collector_state()->last_young_gc(), "must be"); 2067 return MixedGC; 2068 } else { 2069 assert(collector_state()->last_gc_was_young(), "must be"); 2070 assert(!collector_state()->during_initial_mark_pause(), "must be"); 2071 assert(!collector_state()->last_young_gc(), "must be"); 2072 return YoungOnlyGC; 2073 } 2074 } 2075 2076 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) { 2077 // Manage the MMU tracker. For some reason it ignores Full GCs. 2078 if (kind != FullGC) { 2079 _mmu_tracker->add_pause(start, end); 2080 } 2081 // Manage the mutator time tracking from initial mark to first mixed gc. 2082 switch (kind) { 2083 case FullGC: 2084 abort_time_to_mixed_tracking(); 2085 break; 2086 case Cleanup: 2087 case Remark: 2088 case YoungOnlyGC: 2089 case LastYoungGC: 2090 _initial_mark_to_mixed.add_pause(end - start); 2091 break; 2092 case InitialMarkGC: 2093 _initial_mark_to_mixed.record_initial_mark_end(end); 2094 break; 2095 case MixedGC: 2096 _initial_mark_to_mixed.record_mixed_gc_start(start); 2097 break; 2098 default: 2099 ShouldNotReachHere(); 2100 } 2101 } 2102 2103 void G1CollectorPolicy::abort_time_to_mixed_tracking() { 2104 _initial_mark_to_mixed.reset(); 2105 } 2106 2107 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str, 2108 const char* false_action_str) const { 2109 CollectionSetChooser* cset_chooser = _collectionSetChooser; 2110 if (cset_chooser->is_empty()) { 2111 ergo_verbose0(ErgoMixedGCs, 2112 false_action_str, 2113 ergo_format_reason("candidate old regions not available")); 2114 return false; 2115 } 2116 2117 // Is the amount of uncollected reclaimable space above G1HeapWastePercent? 2118 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 2119 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 2120 double threshold = (double) G1HeapWastePercent; 2121 if (reclaimable_perc <= threshold) { 2122 ergo_verbose4(ErgoMixedGCs, 2123 false_action_str, 2124 ergo_format_reason("reclaimable percentage not over threshold") 2125 ergo_format_region("candidate old regions") 2126 ergo_format_byte_perc("reclaimable") 2127 ergo_format_perc("threshold"), 2128 cset_chooser->remaining_regions(), 2129 reclaimable_bytes, 2130 reclaimable_perc, threshold); 2131 return false; 2132 } 2133 2134 ergo_verbose4(ErgoMixedGCs, 2135 true_action_str, 2136 ergo_format_reason("candidate old regions available") 2137 ergo_format_region("candidate old regions") 2138 ergo_format_byte_perc("reclaimable") 2139 ergo_format_perc("threshold"), 2140 cset_chooser->remaining_regions(), 2141 reclaimable_bytes, 2142 reclaimable_perc, threshold); 2143 return true; 2144 } 2145 2146 uint G1CollectorPolicy::calc_min_old_cset_length() const { 2147 // The min old CSet region bound is based on the maximum desired 2148 // number of mixed GCs after a cycle. I.e., even if some old regions 2149 // look expensive, we should add them to the CSet anyway to make 2150 // sure we go through the available old regions in no more than the 2151 // maximum desired number of mixed GCs. 2152 // 2153 // The calculation is based on the number of marked regions we added 2154 // to the CSet chooser in the first place, not how many remain, so 2155 // that the result is the same during all mixed GCs that follow a cycle. 2156 2157 const size_t region_num = (size_t) _collectionSetChooser->length(); 2158 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); 2159 size_t result = region_num / gc_num; 2160 // emulate ceiling 2161 if (result * gc_num < region_num) { 2162 result += 1; 2163 } 2164 return (uint) result; 2165 } 2166 2167 uint G1CollectorPolicy::calc_max_old_cset_length() const { 2168 // The max old CSet region bound is based on the threshold expressed 2169 // as a percentage of the heap size. I.e., it should bound the 2170 // number of old regions added to the CSet irrespective of how many 2171 // of them are available. 2172 2173 const G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2174 const size_t region_num = g1h->num_regions(); 2175 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; 2176 size_t result = region_num * perc / 100; 2177 // emulate ceiling 2178 if (100 * result < region_num * perc) { 2179 result += 1; 2180 } 2181 return (uint) result; 2182 } 2183 2184 2185 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) { 2186 double young_start_time_sec = os::elapsedTime(); 2187 2188 YoungList* young_list = _g1->young_list(); 2189 finalize_incremental_cset_building(); 2190 2191 guarantee(target_pause_time_ms > 0.0, 2192 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms); 2193 guarantee(_collection_set == NULL, "Precondition"); 2194 2195 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards); 2196 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0); 2197 2198 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 2199 "start choosing CSet", 2200 ergo_format_size("_pending_cards") 2201 ergo_format_ms("predicted base time") 2202 ergo_format_ms("remaining time") 2203 ergo_format_ms("target pause time"), 2204 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms); 2205 2206 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young()); 2207 2208 if (collector_state()->last_gc_was_young()) { 2209 _trace_young_gen_time_data.increment_young_collection_count(); 2210 } else { 2211 _trace_young_gen_time_data.increment_mixed_collection_count(); 2212 } 2213 2214 // The young list is laid with the survivor regions from the previous 2215 // pause are appended to the RHS of the young list, i.e. 2216 // [Newly Young Regions ++ Survivors from last pause]. 2217 2218 uint survivor_region_length = young_list->survivor_length(); 2219 uint eden_region_length = young_list->eden_length(); 2220 init_cset_region_lengths(eden_region_length, survivor_region_length); 2221 2222 HeapRegion* hr = young_list->first_survivor_region(); 2223 while (hr != NULL) { 2224 assert(hr->is_survivor(), "badly formed young list"); 2225 // There is a convention that all the young regions in the CSet 2226 // are tagged as "eden", so we do this for the survivors here. We 2227 // use the special set_eden_pre_gc() as it doesn't check that the 2228 // region is free (which is not the case here). 2229 hr->set_eden_pre_gc(); 2230 hr = hr->get_next_young_region(); 2231 } 2232 2233 // Clear the fields that point to the survivor list - they are all young now. 2234 young_list->clear_survivors(); 2235 2236 _collection_set = _inc_cset_head; 2237 _collection_set_bytes_used_before = _inc_cset_bytes_used_before; 2238 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0); 2239 2240 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 2241 "add young regions to CSet", 2242 ergo_format_region("eden") 2243 ergo_format_region("survivors") 2244 ergo_format_ms("predicted young region time") 2245 ergo_format_ms("target pause time"), 2246 eden_region_length, survivor_region_length, 2247 _inc_cset_predicted_elapsed_time_ms, 2248 target_pause_time_ms); 2249 2250 // The number of recorded young regions is the incremental 2251 // collection set's current size 2252 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths); 2253 2254 double young_end_time_sec = os::elapsedTime(); 2255 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0); 2256 2257 return time_remaining_ms; 2258 } 2259 2260 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) { 2261 double non_young_start_time_sec = os::elapsedTime(); 2262 double predicted_old_time_ms = 0.0; 2263 2264 2265 if (!collector_state()->gcs_are_young()) { 2266 CollectionSetChooser* cset_chooser = _collectionSetChooser; 2267 cset_chooser->verify(); 2268 const uint min_old_cset_length = calc_min_old_cset_length(); 2269 const uint max_old_cset_length = calc_max_old_cset_length(); 2270 2271 uint expensive_region_num = 0; 2272 bool check_time_remaining = adaptive_young_list_length(); 2273 2274 HeapRegion* hr = cset_chooser->peek(); 2275 while (hr != NULL) { 2276 if (old_cset_region_length() >= max_old_cset_length) { 2277 // Added maximum number of old regions to the CSet. 2278 ergo_verbose2(ErgoCSetConstruction, 2279 "finish adding old regions to CSet", 2280 ergo_format_reason("old CSet region num reached max") 2281 ergo_format_region("old") 2282 ergo_format_region("max"), 2283 old_cset_region_length(), max_old_cset_length); 2284 break; 2285 } 2286 2287 2288 // Stop adding regions if the remaining reclaimable space is 2289 // not above G1HeapWastePercent. 2290 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 2291 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 2292 double threshold = (double) G1HeapWastePercent; 2293 if (reclaimable_perc <= threshold) { 2294 // We've added enough old regions that the amount of uncollected 2295 // reclaimable space is at or below the waste threshold. Stop 2296 // adding old regions to the CSet. 2297 ergo_verbose5(ErgoCSetConstruction, 2298 "finish adding old regions to CSet", 2299 ergo_format_reason("reclaimable percentage not over threshold") 2300 ergo_format_region("old") 2301 ergo_format_region("max") 2302 ergo_format_byte_perc("reclaimable") 2303 ergo_format_perc("threshold"), 2304 old_cset_region_length(), 2305 max_old_cset_length, 2306 reclaimable_bytes, 2307 reclaimable_perc, threshold); 2308 break; 2309 } 2310 2311 double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); 2312 if (check_time_remaining) { 2313 if (predicted_time_ms > time_remaining_ms) { 2314 // Too expensive for the current CSet. 2315 2316 if (old_cset_region_length() >= min_old_cset_length) { 2317 // We have added the minimum number of old regions to the CSet, 2318 // we are done with this CSet. 2319 ergo_verbose4(ErgoCSetConstruction, 2320 "finish adding old regions to CSet", 2321 ergo_format_reason("predicted time is too high") 2322 ergo_format_ms("predicted time") 2323 ergo_format_ms("remaining time") 2324 ergo_format_region("old") 2325 ergo_format_region("min"), 2326 predicted_time_ms, time_remaining_ms, 2327 old_cset_region_length(), min_old_cset_length); 2328 break; 2329 } 2330 2331 // We'll add it anyway given that we haven't reached the 2332 // minimum number of old regions. 2333 expensive_region_num += 1; 2334 } 2335 } else { 2336 if (old_cset_region_length() >= min_old_cset_length) { 2337 // In the non-auto-tuning case, we'll finish adding regions 2338 // to the CSet if we reach the minimum. 2339 ergo_verbose2(ErgoCSetConstruction, 2340 "finish adding old regions to CSet", 2341 ergo_format_reason("old CSet region num reached min") 2342 ergo_format_region("old") 2343 ergo_format_region("min"), 2344 old_cset_region_length(), min_old_cset_length); 2345 break; 2346 } 2347 } 2348 2349 // We will add this region to the CSet. 2350 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); 2351 predicted_old_time_ms += predicted_time_ms; 2352 cset_chooser->pop(); // already have region via peek() 2353 _g1->old_set_remove(hr); 2354 add_old_region_to_cset(hr); 2355 2356 hr = cset_chooser->peek(); 2357 } 2358 if (hr == NULL) { 2359 ergo_verbose0(ErgoCSetConstruction, 2360 "finish adding old regions to CSet", 2361 ergo_format_reason("candidate old regions not available")); 2362 } 2363 2364 if (expensive_region_num > 0) { 2365 // We print the information once here at the end, predicated on 2366 // whether we added any apparently expensive regions or not, to 2367 // avoid generating output per region. 2368 ergo_verbose4(ErgoCSetConstruction, 2369 "added expensive regions to CSet", 2370 ergo_format_reason("old CSet region num not reached min") 2371 ergo_format_region("old") 2372 ergo_format_region("expensive") 2373 ergo_format_region("min") 2374 ergo_format_ms("remaining time"), 2375 old_cset_region_length(), 2376 expensive_region_num, 2377 min_old_cset_length, 2378 time_remaining_ms); 2379 } 2380 2381 cset_chooser->verify(); 2382 } 2383 2384 stop_incremental_cset_building(); 2385 2386 ergo_verbose3(ErgoCSetConstruction, 2387 "finish choosing CSet", 2388 ergo_format_region("old") 2389 ergo_format_ms("predicted old region time") 2390 ergo_format_ms("time remaining"), 2391 old_cset_region_length(), 2392 predicted_old_time_ms, time_remaining_ms); 2393 2394 double non_young_end_time_sec = os::elapsedTime(); 2395 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); 2396 } 2397 2398 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) { 2399 if(TraceYoungGenTime) { 2400 _all_stop_world_times_ms.add(time_to_stop_the_world_ms); 2401 } 2402 } 2403 2404 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) { 2405 if(TraceYoungGenTime) { 2406 _all_yield_times_ms.add(yield_time_ms); 2407 } 2408 } 2409 2410 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) { 2411 if(TraceYoungGenTime) { 2412 _total.add(pause_time_ms); 2413 _other.add(pause_time_ms - phase_times->accounted_time_ms()); 2414 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms()); 2415 _parallel.add(phase_times->cur_collection_par_time_ms()); 2416 _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan)); 2417 _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering)); 2418 _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS)); 2419 _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS)); 2420 _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy)); 2421 _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination)); 2422 2423 double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) + 2424 phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) + 2425 phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) + 2426 phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) + 2427 phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) + 2428 phase_times->average_time_ms(G1GCPhaseTimes::Termination); 2429 2430 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time; 2431 _parallel_other.add(parallel_other_time); 2432 _clear_ct.add(phase_times->cur_clear_ct_time_ms()); 2433 } 2434 } 2435 2436 void TraceYoungGenTimeData::increment_young_collection_count() { 2437 if(TraceYoungGenTime) { 2438 ++_young_pause_num; 2439 } 2440 } 2441 2442 void TraceYoungGenTimeData::increment_mixed_collection_count() { 2443 if(TraceYoungGenTime) { 2444 ++_mixed_pause_num; 2445 } 2446 } 2447 2448 void TraceYoungGenTimeData::print_summary(const char* str, 2449 const NumberSeq* seq) const { 2450 double sum = seq->sum(); 2451 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)", 2452 str, sum / 1000.0, seq->avg()); 2453 } 2454 2455 void TraceYoungGenTimeData::print_summary_sd(const char* str, 2456 const NumberSeq* seq) const { 2457 print_summary(str, seq); 2458 gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)", 2459 "(num", seq->num(), seq->sd(), seq->maximum()); 2460 } 2461 2462 void TraceYoungGenTimeData::print() const { 2463 if (!TraceYoungGenTime) { 2464 return; 2465 } 2466 2467 gclog_or_tty->print_cr("ALL PAUSES"); 2468 print_summary_sd(" Total", &_total); 2469 gclog_or_tty->cr(); 2470 gclog_or_tty->cr(); 2471 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num); 2472 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num); 2473 gclog_or_tty->cr(); 2474 2475 gclog_or_tty->print_cr("EVACUATION PAUSES"); 2476 2477 if (_young_pause_num == 0 && _mixed_pause_num == 0) { 2478 gclog_or_tty->print_cr("none"); 2479 } else { 2480 print_summary_sd(" Evacuation Pauses", &_total); 2481 print_summary(" Root Region Scan Wait", &_root_region_scan_wait); 2482 print_summary(" Parallel Time", &_parallel); 2483 print_summary(" Ext Root Scanning", &_ext_root_scan); 2484 print_summary(" SATB Filtering", &_satb_filtering); 2485 print_summary(" Update RS", &_update_rs); 2486 print_summary(" Scan RS", &_scan_rs); 2487 print_summary(" Object Copy", &_obj_copy); 2488 print_summary(" Termination", &_termination); 2489 print_summary(" Parallel Other", &_parallel_other); 2490 print_summary(" Clear CT", &_clear_ct); 2491 print_summary(" Other", &_other); 2492 } 2493 gclog_or_tty->cr(); 2494 2495 gclog_or_tty->print_cr("MISC"); 2496 print_summary_sd(" Stop World", &_all_stop_world_times_ms); 2497 print_summary_sd(" Yields", &_all_yield_times_ms); 2498 } 2499 2500 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) { 2501 if (TraceOldGenTime) { 2502 _all_full_gc_times.add(full_gc_time_ms); 2503 } 2504 } 2505 2506 void TraceOldGenTimeData::print() const { 2507 if (!TraceOldGenTime) { 2508 return; 2509 } 2510 2511 if (_all_full_gc_times.num() > 0) { 2512 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s", 2513 _all_full_gc_times.num(), 2514 _all_full_gc_times.sum() / 1000.0); 2515 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg()); 2516 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]", 2517 _all_full_gc_times.sd(), 2518 _all_full_gc_times.maximum()); 2519 } 2520 }