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