1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/g1/concurrentG1Refine.hpp" 27 #include "gc_implementation/g1/concurrentMark.hpp" 28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 30 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 31 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 33 #include "gc_implementation/g1/g1Log.hpp" 34 #include "gc_implementation/g1/heapRegionRemSet.hpp" 35 #include "gc_implementation/shared/gcPolicyCounters.hpp" 36 #include "runtime/arguments.hpp" 37 #include "runtime/java.hpp" 38 #include "runtime/mutexLocker.hpp" 39 #include "utilities/debug.hpp" 40 41 // Different defaults for different number of GC threads 42 // They were chosen by running GCOld and SPECjbb on debris with different 43 // numbers of GC threads and choosing them based on the results 44 45 // all the same 46 static double rs_length_diff_defaults[] = { 47 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 48 }; 49 50 static double cost_per_card_ms_defaults[] = { 51 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015 52 }; 53 54 // all the same 55 static double young_cards_per_entry_ratio_defaults[] = { 56 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 57 }; 58 59 static double cost_per_entry_ms_defaults[] = { 60 0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005 61 }; 62 63 static double cost_per_byte_ms_defaults[] = { 64 0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009 65 }; 66 67 // these should be pretty consistent 68 static double constant_other_time_ms_defaults[] = { 69 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 70 }; 71 72 73 static double young_other_cost_per_region_ms_defaults[] = { 74 0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1 75 }; 76 77 static double non_young_other_cost_per_region_ms_defaults[] = { 78 1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30 79 }; 80 81 G1CollectorPolicy::G1CollectorPolicy() : 82 _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads() 83 ? ParallelGCThreads : 1), 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 _gcs_are_young(true), 112 113 _during_marking(false), 114 _in_marking_window(false), 115 _in_marking_window_im(false), 116 117 _recent_prev_end_times_for_all_gcs_sec( 118 new TruncatedSeq(NumPrevPausesForHeuristics)), 119 120 _recent_avg_pause_time_ratio(0.0), 121 122 _initiate_conc_mark_if_possible(false), 123 _during_initial_mark_pause(false), 124 _last_young_gc(false), 125 _last_gc_was_young(false), 126 127 _eden_bytes_before_gc(0), 128 _survivor_bytes_before_gc(0), 129 _capacity_before_gc(0), 130 131 _eden_cset_region_length(0), 132 _survivor_cset_region_length(0), 133 _old_cset_region_length(0), 134 135 _collection_set(NULL), 136 _collection_set_bytes_used_before(0), 137 138 // Incremental CSet attributes 139 _inc_cset_build_state(Inactive), 140 _inc_cset_head(NULL), 141 _inc_cset_tail(NULL), 142 _inc_cset_bytes_used_before(0), 143 _inc_cset_max_finger(NULL), 144 _inc_cset_recorded_rs_lengths(0), 145 _inc_cset_recorded_rs_lengths_diffs(0), 146 _inc_cset_predicted_elapsed_time_ms(0.0), 147 _inc_cset_predicted_elapsed_time_ms_diffs(0.0), 148 149 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 150 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 151 #endif // _MSC_VER 152 153 _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived", 154 G1YoungSurvRateNumRegionsSummary)), 155 _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor", 156 G1YoungSurvRateNumRegionsSummary)), 157 // add here any more surv rate groups 158 _recorded_survivor_regions(0), 159 _recorded_survivor_head(NULL), 160 _recorded_survivor_tail(NULL), 161 _survivors_age_table(true), 162 163 _gc_overhead_perc(0.0) { 164 165 // Set up the region size and associated fields. Given that the 166 // policy is created before the heap, we have to set this up here, 167 // so it's done as soon as possible. 168 HeapRegion::setup_heap_region_size(Arguments::min_heap_size()); 169 HeapRegionRemSet::setup_remset_size(); 170 171 G1ErgoVerbose::initialize(); 172 if (PrintAdaptiveSizePolicy) { 173 // Currently, we only use a single switch for all the heuristics. 174 G1ErgoVerbose::set_enabled(true); 175 // Given that we don't currently have a verboseness level 176 // parameter, we'll hardcode this to high. This can be easily 177 // changed in the future. 178 G1ErgoVerbose::set_level(ErgoHigh); 179 } else { 180 G1ErgoVerbose::set_enabled(false); 181 } 182 183 // Verify PLAB sizes 184 const size_t region_size = HeapRegion::GrainWords; 185 if (YoungPLABSize > region_size || OldPLABSize > region_size) { 186 char buffer[128]; 187 jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT, 188 OldPLABSize > region_size ? "Old" : "Young", region_size); 189 vm_exit_during_initialization(buffer); 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 _young_cards_per_entry_ratio_seq->add( 202 young_cards_per_entry_ratio_defaults[index]); 203 _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]); 204 _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]); 205 _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]); 206 _young_other_cost_per_region_ms_seq->add( 207 young_other_cost_per_region_ms_defaults[index]); 208 _non_young_other_cost_per_region_ms_seq->add( 209 non_young_other_cost_per_region_ms_defaults[index]); 210 211 // Below, we might need to calculate the pause time target based on 212 // the pause interval. When we do so we are going to give G1 maximum 213 // flexibility and allow it to do pauses when it needs to. So, we'll 214 // arrange that the pause interval to be pause time target + 1 to 215 // ensure that a) the pause time target is maximized with respect to 216 // the pause interval and b) we maintain the invariant that pause 217 // time target < pause interval. If the user does not want this 218 // maximum flexibility, they will have to set the pause interval 219 // explicitly. 220 221 // First make sure that, if either parameter is set, its value is 222 // reasonable. 223 if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 224 if (MaxGCPauseMillis < 1) { 225 vm_exit_during_initialization("MaxGCPauseMillis should be " 226 "greater than 0"); 227 } 228 } 229 if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 230 if (GCPauseIntervalMillis < 1) { 231 vm_exit_during_initialization("GCPauseIntervalMillis should be " 232 "greater than 0"); 233 } 234 } 235 236 // Then, if the pause time target parameter was not set, set it to 237 // the default value. 238 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 239 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 240 // The default pause time target in G1 is 200ms 241 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200); 242 } else { 243 // We do not allow the pause interval to be set without the 244 // pause time target 245 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set " 246 "without setting MaxGCPauseMillis"); 247 } 248 } 249 250 // Then, if the interval parameter was not set, set it according to 251 // the pause time target (this will also deal with the case when the 252 // pause time target is the default value). 253 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 254 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1); 255 } 256 257 // Finally, make sure that the two parameters are consistent. 258 if (MaxGCPauseMillis >= GCPauseIntervalMillis) { 259 char buffer[256]; 260 jio_snprintf(buffer, 256, 261 "MaxGCPauseMillis (%u) should be less than " 262 "GCPauseIntervalMillis (%u)", 263 MaxGCPauseMillis, GCPauseIntervalMillis); 264 vm_exit_during_initialization(buffer); 265 } 266 267 double max_gc_time = (double) MaxGCPauseMillis / 1000.0; 268 double time_slice = (double) GCPauseIntervalMillis / 1000.0; 269 _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time); 270 271 uintx confidence_perc = G1ConfidencePercent; 272 // Put an artificial ceiling on this so that it's not set to a silly value. 273 if (confidence_perc > 100) { 274 confidence_perc = 100; 275 warning("G1ConfidencePercent is set to a value that is too large, " 276 "it's been updated to %u", confidence_perc); 277 } 278 _sigma = (double) confidence_perc / 100.0; 279 280 // start conservatively (around 50ms is about right) 281 _concurrent_mark_remark_times_ms->add(0.05); 282 _concurrent_mark_cleanup_times_ms->add(0.20); 283 _tenuring_threshold = MaxTenuringThreshold; 284 // _max_survivor_regions will be calculated by 285 // update_young_list_target_length() during initialization. 286 _max_survivor_regions = 0; 287 288 assert(GCTimeRatio > 0, 289 "we should have set it to a default value set_g1_gc_flags() " 290 "if a user set it to 0"); 291 _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio)); 292 293 uintx reserve_perc = G1ReservePercent; 294 // Put an artificial ceiling on this so that it's not set to a silly value. 295 if (reserve_perc > 50) { 296 reserve_perc = 50; 297 warning("G1ReservePercent is set to a value that is too large, " 298 "it's been updated to %u", reserve_perc); 299 } 300 _reserve_factor = (double) reserve_perc / 100.0; 301 // This will be set when the heap is expanded 302 // for the first time during initialization. 303 _reserve_regions = 0; 304 305 initialize_all(); 306 _collectionSetChooser = new CollectionSetChooser(); 307 _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags 308 } 309 310 void G1CollectorPolicy::initialize_flags() { 311 set_min_alignment(HeapRegion::GrainBytes); 312 set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name())); 313 if (SurvivorRatio < 1) { 314 vm_exit_during_initialization("Invalid survivor ratio specified"); 315 } 316 CollectorPolicy::initialize_flags(); 317 } 318 319 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) { 320 assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max"); 321 assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds"); 322 assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds"); 323 324 if (FLAG_IS_CMDLINE(NewRatio)) { 325 if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) { 326 warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio"); 327 } else { 328 _sizer_kind = SizerNewRatio; 329 _adaptive_size = false; 330 return; 331 } 332 } 333 334 if (FLAG_IS_CMDLINE(NewSize)) { 335 _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes), 336 1U); 337 if (FLAG_IS_CMDLINE(MaxNewSize)) { 338 _max_desired_young_length = 339 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 340 1U); 341 _sizer_kind = SizerMaxAndNewSize; 342 _adaptive_size = _min_desired_young_length == _max_desired_young_length; 343 } else { 344 _sizer_kind = SizerNewSizeOnly; 345 } 346 } else if (FLAG_IS_CMDLINE(MaxNewSize)) { 347 _max_desired_young_length = 348 MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes), 349 1U); 350 _sizer_kind = SizerMaxNewSizeOnly; 351 } 352 } 353 354 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) { 355 uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100; 356 return MAX2(1U, default_value); 357 } 358 359 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) { 360 uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100; 361 return MAX2(1U, default_value); 362 } 363 364 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) { 365 assert(new_number_of_heap_regions > 0, "Heap must be initialized"); 366 367 switch (_sizer_kind) { 368 case SizerDefaults: 369 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions); 370 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions); 371 break; 372 case SizerNewSizeOnly: 373 _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions); 374 _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length); 375 break; 376 case SizerMaxNewSizeOnly: 377 _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions); 378 _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length); 379 break; 380 case SizerMaxAndNewSize: 381 // Do nothing. Values set on the command line, don't update them at runtime. 382 break; 383 case SizerNewRatio: 384 _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1); 385 _max_desired_young_length = _min_desired_young_length; 386 break; 387 default: 388 ShouldNotReachHere(); 389 } 390 391 assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values"); 392 } 393 394 void G1CollectorPolicy::init() { 395 // Set aside an initial future to_space. 396 _g1 = G1CollectedHeap::heap(); 397 398 assert(Heap_lock->owned_by_self(), "Locking discipline."); 399 400 initialize_gc_policy_counters(); 401 402 if (adaptive_young_list_length()) { 403 _young_list_fixed_length = 0; 404 } else { 405 _young_list_fixed_length = _young_gen_sizer->min_desired_young_length(); 406 } 407 _free_regions_at_end_of_collection = _g1->free_regions(); 408 update_young_list_target_length(); 409 410 // We may immediately start allocating regions and placing them on the 411 // collection set list. Initialize the per-collection set info 412 start_incremental_cset_building(); 413 } 414 415 // Create the jstat counters for the policy. 416 void G1CollectorPolicy::initialize_gc_policy_counters() { 417 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3); 418 } 419 420 bool G1CollectorPolicy::predict_will_fit(uint young_length, 421 double base_time_ms, 422 uint base_free_regions, 423 double target_pause_time_ms) { 424 if (young_length >= base_free_regions) { 425 // end condition 1: not enough space for the young regions 426 return false; 427 } 428 429 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1); 430 size_t bytes_to_copy = 431 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); 432 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy); 433 double young_other_time_ms = predict_young_other_time_ms(young_length); 434 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms; 435 if (pause_time_ms > target_pause_time_ms) { 436 // end condition 2: prediction is over the target pause time 437 return false; 438 } 439 440 size_t free_bytes = 441 (base_free_regions - young_length) * HeapRegion::GrainBytes; 442 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) { 443 // end condition 3: out-of-space (conservatively!) 444 return false; 445 } 446 447 // success! 448 return true; 449 } 450 451 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) { 452 // re-calculate the necessary reserve 453 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; 454 // We use ceiling so that if reserve_regions_d is > 0.0 (but 455 // smaller than 1.0) we'll get 1. 456 _reserve_regions = (uint) ceil(reserve_regions_d); 457 458 _young_gen_sizer->heap_size_changed(new_number_of_regions); 459 } 460 461 uint G1CollectorPolicy::calculate_young_list_desired_min_length( 462 uint base_min_length) { 463 uint desired_min_length = 0; 464 if (adaptive_young_list_length()) { 465 if (_alloc_rate_ms_seq->num() > 3) { 466 double now_sec = os::elapsedTime(); 467 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; 468 double alloc_rate_ms = predict_alloc_rate_ms(); 469 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); 470 } else { 471 // otherwise we don't have enough info to make the prediction 472 } 473 } 474 desired_min_length += base_min_length; 475 // make sure we don't go below any user-defined minimum bound 476 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length); 477 } 478 479 uint G1CollectorPolicy::calculate_young_list_desired_max_length() { 480 // Here, we might want to also take into account any additional 481 // constraints (i.e., user-defined minimum bound). Currently, we 482 // effectively don't set this bound. 483 return _young_gen_sizer->max_desired_young_length(); 484 } 485 486 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) { 487 if (rs_lengths == (size_t) -1) { 488 // if it's set to the default value (-1), we should predict it; 489 // otherwise, use the given value. 490 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq); 491 } 492 493 // Calculate the absolute and desired min bounds. 494 495 // This is how many young regions we already have (currently: the survivors). 496 uint base_min_length = recorded_survivor_regions(); 497 // This is the absolute minimum young length, which ensures that we 498 // can allocate one eden region in the worst-case. 499 uint absolute_min_length = base_min_length + 1; 500 uint desired_min_length = 501 calculate_young_list_desired_min_length(base_min_length); 502 if (desired_min_length < absolute_min_length) { 503 desired_min_length = absolute_min_length; 504 } 505 506 // Calculate the absolute and desired max bounds. 507 508 // We will try our best not to "eat" into the reserve. 509 uint absolute_max_length = 0; 510 if (_free_regions_at_end_of_collection > _reserve_regions) { 511 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; 512 } 513 uint desired_max_length = calculate_young_list_desired_max_length(); 514 if (desired_max_length > absolute_max_length) { 515 desired_max_length = absolute_max_length; 516 } 517 518 uint young_list_target_length = 0; 519 if (adaptive_young_list_length()) { 520 if (gcs_are_young()) { 521 young_list_target_length = 522 calculate_young_list_target_length(rs_lengths, 523 base_min_length, 524 desired_min_length, 525 desired_max_length); 526 _rs_lengths_prediction = rs_lengths; 527 } else { 528 // Don't calculate anything and let the code below bound it to 529 // the desired_min_length, i.e., do the next GC as soon as 530 // possible to maximize how many old regions we can add to it. 531 } 532 } else { 533 // The user asked for a fixed young gen so we'll fix the young gen 534 // whether the next GC is young or mixed. 535 young_list_target_length = _young_list_fixed_length; 536 } 537 538 // Make sure we don't go over the desired max length, nor under the 539 // desired min length. In case they clash, desired_min_length wins 540 // which is why that test is second. 541 if (young_list_target_length > desired_max_length) { 542 young_list_target_length = desired_max_length; 543 } 544 if (young_list_target_length < desired_min_length) { 545 young_list_target_length = desired_min_length; 546 } 547 548 assert(young_list_target_length > recorded_survivor_regions(), 549 "we should be able to allocate at least one eden region"); 550 assert(young_list_target_length >= absolute_min_length, "post-condition"); 551 _young_list_target_length = young_list_target_length; 552 553 update_max_gc_locker_expansion(); 554 } 555 556 uint 557 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths, 558 uint base_min_length, 559 uint desired_min_length, 560 uint desired_max_length) { 561 assert(adaptive_young_list_length(), "pre-condition"); 562 assert(gcs_are_young(), "only call this for young GCs"); 563 564 // In case some edge-condition makes the desired max length too small... 565 if (desired_max_length <= desired_min_length) { 566 return desired_min_length; 567 } 568 569 // We'll adjust min_young_length and max_young_length not to include 570 // the already allocated young regions (i.e., so they reflect the 571 // min and max eden regions we'll allocate). The base_min_length 572 // will be reflected in the predictions by the 573 // survivor_regions_evac_time prediction. 574 assert(desired_min_length > base_min_length, "invariant"); 575 uint min_young_length = desired_min_length - base_min_length; 576 assert(desired_max_length > base_min_length, "invariant"); 577 uint max_young_length = desired_max_length - base_min_length; 578 579 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; 580 double survivor_regions_evac_time = predict_survivor_regions_evac_time(); 581 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq); 582 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff(); 583 size_t scanned_cards = predict_young_card_num(adj_rs_lengths); 584 double base_time_ms = 585 predict_base_elapsed_time_ms(pending_cards, scanned_cards) + 586 survivor_regions_evac_time; 587 uint available_free_regions = _free_regions_at_end_of_collection; 588 uint base_free_regions = 0; 589 if (available_free_regions > _reserve_regions) { 590 base_free_regions = available_free_regions - _reserve_regions; 591 } 592 593 // Here, we will make sure that the shortest young length that 594 // makes sense fits within the target pause time. 595 596 if (predict_will_fit(min_young_length, base_time_ms, 597 base_free_regions, target_pause_time_ms)) { 598 // The shortest young length will fit into the target pause time; 599 // we'll now check whether the absolute maximum number of young 600 // regions will fit in the target pause time. If not, we'll do 601 // a binary search between min_young_length and max_young_length. 602 if (predict_will_fit(max_young_length, base_time_ms, 603 base_free_regions, target_pause_time_ms)) { 604 // The maximum young length will fit into the target pause time. 605 // We are done so set min young length to the maximum length (as 606 // the result is assumed to be returned in min_young_length). 607 min_young_length = max_young_length; 608 } else { 609 // The maximum possible number of young regions will not fit within 610 // the target pause time so we'll search for the optimal 611 // length. The loop invariants are: 612 // 613 // min_young_length < max_young_length 614 // min_young_length is known to fit into the target pause time 615 // max_young_length is known not to fit into the target pause time 616 // 617 // Going into the loop we know the above hold as we've just 618 // checked them. Every time around the loop we check whether 619 // the middle value between min_young_length and 620 // max_young_length fits into the target pause time. If it 621 // does, it becomes the new min. If it doesn't, it becomes 622 // the new max. This way we maintain the loop invariants. 623 624 assert(min_young_length < max_young_length, "invariant"); 625 uint diff = (max_young_length - min_young_length) / 2; 626 while (diff > 0) { 627 uint young_length = min_young_length + diff; 628 if (predict_will_fit(young_length, base_time_ms, 629 base_free_regions, target_pause_time_ms)) { 630 min_young_length = young_length; 631 } else { 632 max_young_length = young_length; 633 } 634 assert(min_young_length < max_young_length, "invariant"); 635 diff = (max_young_length - min_young_length) / 2; 636 } 637 // The results is min_young_length which, according to the 638 // loop invariants, should fit within the target pause time. 639 640 // These are the post-conditions of the binary search above: 641 assert(min_young_length < max_young_length, 642 "otherwise we should have discovered that max_young_length " 643 "fits into the pause target and not done the binary search"); 644 assert(predict_will_fit(min_young_length, base_time_ms, 645 base_free_regions, target_pause_time_ms), 646 "min_young_length, the result of the binary search, should " 647 "fit into the pause target"); 648 assert(!predict_will_fit(min_young_length + 1, base_time_ms, 649 base_free_regions, target_pause_time_ms), 650 "min_young_length, the result of the binary search, should be " 651 "optimal, so no larger length should fit into the pause target"); 652 } 653 } else { 654 // Even the minimum length doesn't fit into the pause time 655 // target, return it as the result nevertheless. 656 } 657 return base_min_length + min_young_length; 658 } 659 660 double G1CollectorPolicy::predict_survivor_regions_evac_time() { 661 double survivor_regions_evac_time = 0.0; 662 for (HeapRegion * r = _recorded_survivor_head; 663 r != NULL && r != _recorded_survivor_tail->get_next_young_region(); 664 r = r->get_next_young_region()) { 665 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young()); 666 } 667 return survivor_regions_evac_time; 668 } 669 670 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() { 671 guarantee( adaptive_young_list_length(), "should not call this otherwise" ); 672 673 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths(); 674 if (rs_lengths > _rs_lengths_prediction) { 675 // add 10% to avoid having to recalculate often 676 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; 677 update_young_list_target_length(rs_lengths_prediction); 678 } 679 } 680 681 682 683 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size, 684 bool is_tlab, 685 bool* gc_overhead_limit_was_exceeded) { 686 guarantee(false, "Not using this policy feature yet."); 687 return NULL; 688 } 689 690 // This method controls how a collector handles one or more 691 // of its generations being fully allocated. 692 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size, 693 bool is_tlab) { 694 guarantee(false, "Not using this policy feature yet."); 695 return NULL; 696 } 697 698 699 #ifndef PRODUCT 700 bool G1CollectorPolicy::verify_young_ages() { 701 HeapRegion* head = _g1->young_list()->first_region(); 702 return 703 verify_young_ages(head, _short_lived_surv_rate_group); 704 // also call verify_young_ages on any additional surv rate groups 705 } 706 707 bool 708 G1CollectorPolicy::verify_young_ages(HeapRegion* head, 709 SurvRateGroup *surv_rate_group) { 710 guarantee( surv_rate_group != NULL, "pre-condition" ); 711 712 const char* name = surv_rate_group->name(); 713 bool ret = true; 714 int prev_age = -1; 715 716 for (HeapRegion* curr = head; 717 curr != NULL; 718 curr = curr->get_next_young_region()) { 719 SurvRateGroup* group = curr->surv_rate_group(); 720 if (group == NULL && !curr->is_survivor()) { 721 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name); 722 ret = false; 723 } 724 725 if (surv_rate_group == group) { 726 int age = curr->age_in_surv_rate_group(); 727 728 if (age < 0) { 729 gclog_or_tty->print_cr("## %s: encountered negative age", name); 730 ret = false; 731 } 732 733 if (age <= prev_age) { 734 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing " 735 "(%d, %d)", name, age, prev_age); 736 ret = false; 737 } 738 prev_age = age; 739 } 740 } 741 742 return ret; 743 } 744 #endif // PRODUCT 745 746 void G1CollectorPolicy::record_full_collection_start() { 747 _full_collection_start_sec = os::elapsedTime(); 748 record_heap_size_info_at_start(); 749 // Release the future to-space so that it is available for compaction into. 750 _g1->set_full_collection(); 751 } 752 753 void G1CollectorPolicy::record_full_collection_end() { 754 // Consider this like a collection pause for the purposes of allocation 755 // since last pause. 756 double end_sec = os::elapsedTime(); 757 double full_gc_time_sec = end_sec - _full_collection_start_sec; 758 double full_gc_time_ms = full_gc_time_sec * 1000.0; 759 760 _trace_gen1_time_data.record_full_collection(full_gc_time_ms); 761 762 update_recent_gc_times(end_sec, full_gc_time_ms); 763 764 _g1->clear_full_collection(); 765 766 // "Nuke" the heuristics that control the young/mixed GC 767 // transitions and make sure we start with young GCs after the Full GC. 768 set_gcs_are_young(true); 769 _last_young_gc = false; 770 clear_initiate_conc_mark_if_possible(); 771 clear_during_initial_mark_pause(); 772 _in_marking_window = false; 773 _in_marking_window_im = false; 774 775 _short_lived_surv_rate_group->start_adding_regions(); 776 // also call this on any additional surv rate groups 777 778 record_survivor_regions(0, NULL, NULL); 779 780 _free_regions_at_end_of_collection = _g1->free_regions(); 781 // Reset survivors SurvRateGroup. 782 _survivor_surv_rate_group->reset(); 783 update_young_list_target_length(); 784 _collectionSetChooser->clear(); 785 } 786 787 void G1CollectorPolicy::record_stop_world_start() { 788 _stop_world_start = os::elapsedTime(); 789 } 790 791 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) { 792 // We only need to do this here as the policy will only be applied 793 // to the GC we're about to start. so, no point is calculating this 794 // every time we calculate / recalculate the target young length. 795 update_survivors_policy(); 796 797 assert(_g1->used() == _g1->recalculate_used(), 798 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT, 799 _g1->used(), _g1->recalculate_used())); 800 801 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0; 802 _trace_gen0_time_data.record_start_collection(s_w_t_ms); 803 _stop_world_start = 0.0; 804 805 record_heap_size_info_at_start(); 806 807 phase_times()->record_cur_collection_start_sec(start_time_sec); 808 _pending_cards = _g1->pending_card_num(); 809 810 _collection_set_bytes_used_before = 0; 811 _bytes_copied_during_gc = 0; 812 813 _last_gc_was_young = false; 814 815 // do that for any other surv rate groups 816 _short_lived_surv_rate_group->stop_adding_regions(); 817 _survivors_age_table.clear(); 818 819 assert( verify_young_ages(), "region age verification" ); 820 } 821 822 void G1CollectorPolicy::record_concurrent_mark_init_end(double 823 mark_init_elapsed_time_ms) { 824 _during_marking = true; 825 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now"); 826 clear_during_initial_mark_pause(); 827 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms; 828 } 829 830 void G1CollectorPolicy::record_concurrent_mark_remark_start() { 831 _mark_remark_start_sec = os::elapsedTime(); 832 _during_marking = false; 833 } 834 835 void G1CollectorPolicy::record_concurrent_mark_remark_end() { 836 double end_time_sec = os::elapsedTime(); 837 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; 838 _concurrent_mark_remark_times_ms->add(elapsed_time_ms); 839 _cur_mark_stop_world_time_ms += elapsed_time_ms; 840 _prev_collection_pause_end_ms += elapsed_time_ms; 841 842 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true); 843 } 844 845 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() { 846 _mark_cleanup_start_sec = os::elapsedTime(); 847 } 848 849 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() { 850 _last_young_gc = true; 851 _in_marking_window = false; 852 } 853 854 void G1CollectorPolicy::record_concurrent_pause() { 855 if (_stop_world_start > 0.0) { 856 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0; 857 _trace_gen0_time_data.record_yield_time(yield_ms); 858 } 859 } 860 861 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { 862 if (_g1->concurrent_mark()->cmThread()->during_cycle()) { 863 return false; 864 } 865 866 size_t marking_initiating_used_threshold = 867 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent; 868 size_t cur_used_bytes = _g1->non_young_capacity_bytes(); 869 size_t alloc_byte_size = alloc_word_size * HeapWordSize; 870 871 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) { 872 if (gcs_are_young()) { 873 ergo_verbose5(ErgoConcCycles, 874 "request concurrent cycle initiation", 875 ergo_format_reason("occupancy higher than threshold") 876 ergo_format_byte("occupancy") 877 ergo_format_byte("allocation request") 878 ergo_format_byte_perc("threshold") 879 ergo_format_str("source"), 880 cur_used_bytes, 881 alloc_byte_size, 882 marking_initiating_used_threshold, 883 (double) InitiatingHeapOccupancyPercent, 884 source); 885 return true; 886 } else { 887 ergo_verbose5(ErgoConcCycles, 888 "do not request concurrent cycle initiation", 889 ergo_format_reason("still doing mixed collections") 890 ergo_format_byte("occupancy") 891 ergo_format_byte("allocation request") 892 ergo_format_byte_perc("threshold") 893 ergo_format_str("source"), 894 cur_used_bytes, 895 alloc_byte_size, 896 marking_initiating_used_threshold, 897 (double) InitiatingHeapOccupancyPercent, 898 source); 899 } 900 } 901 902 return false; 903 } 904 905 // Anything below that is considered to be zero 906 #define MIN_TIMER_GRANULARITY 0.0000001 907 908 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms) { 909 double end_time_sec = os::elapsedTime(); 910 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(), 911 "otherwise, the subtraction below does not make sense"); 912 size_t rs_size = 913 _cur_collection_pause_used_regions_at_start - cset_region_length(); 914 size_t cur_used_bytes = _g1->used(); 915 assert(cur_used_bytes == _g1->recalculate_used(), "It should!"); 916 bool last_pause_included_initial_mark = false; 917 bool update_stats = !_g1->evacuation_failed(); 918 919 #ifndef PRODUCT 920 if (G1YoungSurvRateVerbose) { 921 gclog_or_tty->print_cr(""); 922 _short_lived_surv_rate_group->print(); 923 // do that for any other surv rate groups too 924 } 925 #endif // PRODUCT 926 927 last_pause_included_initial_mark = during_initial_mark_pause(); 928 if (last_pause_included_initial_mark) { 929 record_concurrent_mark_init_end(0.0); 930 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) { 931 // Note: this might have already been set, if during the last 932 // pause we decided to start a cycle but at the beginning of 933 // this pause we decided to postpone it. That's OK. 934 set_initiate_conc_mark_if_possible(); 935 } 936 937 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0, 938 end_time_sec, false); 939 940 size_t freed_bytes = 941 _cur_collection_pause_used_at_start_bytes - cur_used_bytes; 942 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes; 943 944 double survival_fraction = 945 (double)surviving_bytes/ 946 (double)_collection_set_bytes_used_before; 947 948 if (update_stats) { 949 _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times()); 950 // this is where we update the allocation rate of the application 951 double app_time_ms = 952 (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms); 953 if (app_time_ms < MIN_TIMER_GRANULARITY) { 954 // This usually happens due to the timer not having the required 955 // granularity. Some Linuxes are the usual culprits. 956 // We'll just set it to something (arbitrarily) small. 957 app_time_ms = 1.0; 958 } 959 // We maintain the invariant that all objects allocated by mutator 960 // threads will be allocated out of eden regions. So, we can use 961 // the eden region number allocated since the previous GC to 962 // calculate the application's allocate rate. The only exception 963 // to that is humongous objects that are allocated separately. But 964 // given that humongous object allocations do not really affect 965 // either the pause's duration nor when the next pause will take 966 // place we can safely ignore them here. 967 uint regions_allocated = eden_cset_region_length(); 968 double alloc_rate_ms = (double) regions_allocated / app_time_ms; 969 _alloc_rate_ms_seq->add(alloc_rate_ms); 970 971 double interval_ms = 972 (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0; 973 update_recent_gc_times(end_time_sec, pause_time_ms); 974 _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms; 975 if (recent_avg_pause_time_ratio() < 0.0 || 976 (recent_avg_pause_time_ratio() - 1.0 > 0.0)) { 977 #ifndef PRODUCT 978 // Dump info to allow post-facto debugging 979 gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds"); 980 gclog_or_tty->print_cr("-------------------------------------------"); 981 gclog_or_tty->print_cr("Recent GC Times (ms):"); 982 _recent_gc_times_ms->dump(); 983 gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec); 984 _recent_prev_end_times_for_all_gcs_sec->dump(); 985 gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f", 986 _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio()); 987 // In debug mode, terminate the JVM if the user wants to debug at this point. 988 assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above"); 989 #endif // !PRODUCT 990 // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in 991 // CR 6902692 by redoing the manner in which the ratio is incrementally computed. 992 if (_recent_avg_pause_time_ratio < 0.0) { 993 _recent_avg_pause_time_ratio = 0.0; 994 } else { 995 assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant"); 996 _recent_avg_pause_time_ratio = 1.0; 997 } 998 } 999 } 1000 bool new_in_marking_window = _in_marking_window; 1001 bool new_in_marking_window_im = false; 1002 if (during_initial_mark_pause()) { 1003 new_in_marking_window = true; 1004 new_in_marking_window_im = true; 1005 } 1006 1007 if (_last_young_gc) { 1008 // This is supposed to to be the "last young GC" before we start 1009 // doing mixed GCs. Here we decide whether to start mixed GCs or not. 1010 1011 if (!last_pause_included_initial_mark) { 1012 if (next_gc_should_be_mixed("start mixed GCs", 1013 "do not start mixed GCs")) { 1014 set_gcs_are_young(false); 1015 } 1016 } else { 1017 ergo_verbose0(ErgoMixedGCs, 1018 "do not start mixed GCs", 1019 ergo_format_reason("concurrent cycle is about to start")); 1020 } 1021 _last_young_gc = false; 1022 } 1023 1024 if (!_last_gc_was_young) { 1025 // This is a mixed GC. Here we decide whether to continue doing 1026 // mixed GCs or not. 1027 1028 if (!next_gc_should_be_mixed("continue mixed GCs", 1029 "do not continue mixed GCs")) { 1030 set_gcs_are_young(true); 1031 } 1032 } 1033 1034 _short_lived_surv_rate_group->start_adding_regions(); 1035 // do that for any other surv rate groupsx 1036 1037 if (update_stats) { 1038 double cost_per_card_ms = 0.0; 1039 if (_pending_cards > 0) { 1040 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards; 1041 _cost_per_card_ms_seq->add(cost_per_card_ms); 1042 } 1043 1044 size_t cards_scanned = _g1->cards_scanned(); 1045 1046 double cost_per_entry_ms = 0.0; 1047 if (cards_scanned > 10) { 1048 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned; 1049 if (_last_gc_was_young) { 1050 _cost_per_entry_ms_seq->add(cost_per_entry_ms); 1051 } else { 1052 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms); 1053 } 1054 } 1055 1056 if (_max_rs_lengths > 0) { 1057 double cards_per_entry_ratio = 1058 (double) cards_scanned / (double) _max_rs_lengths; 1059 if (_last_gc_was_young) { 1060 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1061 } else { 1062 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1063 } 1064 } 1065 1066 // This is defensive. For a while _max_rs_lengths could get 1067 // smaller than _recorded_rs_lengths which was causing 1068 // rs_length_diff to get very large and mess up the RSet length 1069 // predictions. The reason was unsafe concurrent updates to the 1070 // _inc_cset_recorded_rs_lengths field which the code below guards 1071 // against (see CR 7118202). This bug has now been fixed (see CR 1072 // 7119027). However, I'm still worried that 1073 // _inc_cset_recorded_rs_lengths might still end up somewhat 1074 // inaccurate. The concurrent refinement thread calculates an 1075 // RSet's length concurrently with other CR threads updating it 1076 // which might cause it to calculate the length incorrectly (if, 1077 // say, it's in mid-coarsening). So I'll leave in the defensive 1078 // conditional below just in case. 1079 size_t rs_length_diff = 0; 1080 if (_max_rs_lengths > _recorded_rs_lengths) { 1081 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths; 1082 } 1083 _rs_length_diff_seq->add((double) rs_length_diff); 1084 1085 size_t copied_bytes = surviving_bytes; 1086 double cost_per_byte_ms = 0.0; 1087 if (copied_bytes > 0) { 1088 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes; 1089 if (_in_marking_window) { 1090 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms); 1091 } else { 1092 _cost_per_byte_ms_seq->add(cost_per_byte_ms); 1093 } 1094 } 1095 1096 double all_other_time_ms = pause_time_ms - 1097 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time() 1098 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time()); 1099 1100 double young_other_time_ms = 0.0; 1101 if (young_cset_region_length() > 0) { 1102 young_other_time_ms = 1103 phase_times()->young_cset_choice_time_ms() + 1104 phase_times()->young_free_cset_time_ms(); 1105 _young_other_cost_per_region_ms_seq->add(young_other_time_ms / 1106 (double) young_cset_region_length()); 1107 } 1108 double non_young_other_time_ms = 0.0; 1109 if (old_cset_region_length() > 0) { 1110 non_young_other_time_ms = 1111 phase_times()->non_young_cset_choice_time_ms() + 1112 phase_times()->non_young_free_cset_time_ms(); 1113 1114 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms / 1115 (double) old_cset_region_length()); 1116 } 1117 1118 double constant_other_time_ms = all_other_time_ms - 1119 (young_other_time_ms + non_young_other_time_ms); 1120 _constant_other_time_ms_seq->add(constant_other_time_ms); 1121 1122 double survival_ratio = 0.0; 1123 if (_collection_set_bytes_used_before > 0) { 1124 survival_ratio = (double) _bytes_copied_during_gc / 1125 (double) _collection_set_bytes_used_before; 1126 } 1127 1128 _pending_cards_seq->add((double) _pending_cards); 1129 _rs_lengths_seq->add((double) _max_rs_lengths); 1130 } 1131 1132 _in_marking_window = new_in_marking_window; 1133 _in_marking_window_im = new_in_marking_window_im; 1134 _free_regions_at_end_of_collection = _g1->free_regions(); 1135 update_young_list_target_length(); 1136 1137 // Note that _mmu_tracker->max_gc_time() returns the time in seconds. 1138 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; 1139 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(), 1140 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms); 1141 1142 _collectionSetChooser->verify(); 1143 } 1144 1145 #define EXT_SIZE_FORMAT "%.1f%s" 1146 #define EXT_SIZE_PARAMS(bytes) \ 1147 byte_size_in_proper_unit((double)(bytes)), \ 1148 proper_unit_for_byte_size((bytes)) 1149 1150 void G1CollectorPolicy::record_heap_size_info_at_start() { 1151 YoungList* young_list = _g1->young_list(); 1152 _eden_bytes_before_gc = young_list->eden_used_bytes(); 1153 _survivor_bytes_before_gc = young_list->survivor_used_bytes(); 1154 _capacity_before_gc = _g1->capacity(); 1155 1156 _cur_collection_pause_used_at_start_bytes = _g1->used(); 1157 _cur_collection_pause_used_regions_at_start = _g1->used_regions(); 1158 1159 size_t eden_capacity_before_gc = 1160 (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_bytes_before_gc; 1161 1162 _prev_eden_capacity = eden_capacity_before_gc; 1163 } 1164 1165 void G1CollectorPolicy::print_heap_transition() { 1166 _g1->print_size_transition(gclog_or_tty, 1167 _cur_collection_pause_used_at_start_bytes, _g1->used(), _g1->capacity()); 1168 } 1169 1170 void G1CollectorPolicy::print_detailed_heap_transition() { 1171 YoungList* young_list = _g1->young_list(); 1172 size_t eden_bytes = young_list->eden_used_bytes(); 1173 size_t survivor_bytes = young_list->survivor_used_bytes(); 1174 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes; 1175 size_t used = _g1->used(); 1176 size_t capacity = _g1->capacity(); 1177 size_t eden_capacity = 1178 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes; 1179 1180 gclog_or_tty->print_cr( 1181 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") " 1182 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" " 1183 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->" 1184 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]", 1185 EXT_SIZE_PARAMS(_eden_bytes_before_gc), 1186 EXT_SIZE_PARAMS(_prev_eden_capacity), 1187 EXT_SIZE_PARAMS(eden_bytes), 1188 EXT_SIZE_PARAMS(eden_capacity), 1189 EXT_SIZE_PARAMS(_survivor_bytes_before_gc), 1190 EXT_SIZE_PARAMS(survivor_bytes), 1191 EXT_SIZE_PARAMS(used_before_gc), 1192 EXT_SIZE_PARAMS(_capacity_before_gc), 1193 EXT_SIZE_PARAMS(used), 1194 EXT_SIZE_PARAMS(capacity)); 1195 } 1196 1197 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time, 1198 double update_rs_processed_buffers, 1199 double goal_ms) { 1200 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1201 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine(); 1202 1203 if (G1UseAdaptiveConcRefinement) { 1204 const int k_gy = 3, k_gr = 6; 1205 const double inc_k = 1.1, dec_k = 0.9; 1206 1207 int g = cg1r->green_zone(); 1208 if (update_rs_time > goal_ms) { 1209 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing. 1210 } else { 1211 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) { 1212 g = (int)MAX2(g * inc_k, g + 1.0); 1213 } 1214 } 1215 // Change the refinement threads params 1216 cg1r->set_green_zone(g); 1217 cg1r->set_yellow_zone(g * k_gy); 1218 cg1r->set_red_zone(g * k_gr); 1219 cg1r->reinitialize_threads(); 1220 1221 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1); 1222 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta, 1223 cg1r->yellow_zone()); 1224 // Change the barrier params 1225 dcqs.set_process_completed_threshold(processing_threshold); 1226 dcqs.set_max_completed_queue(cg1r->red_zone()); 1227 } 1228 1229 int curr_queue_size = dcqs.completed_buffers_num(); 1230 if (curr_queue_size >= cg1r->yellow_zone()) { 1231 dcqs.set_completed_queue_padding(curr_queue_size); 1232 } else { 1233 dcqs.set_completed_queue_padding(0); 1234 } 1235 dcqs.notify_if_necessary(); 1236 } 1237 1238 double 1239 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards, 1240 size_t scanned_cards) { 1241 return 1242 predict_rs_update_time_ms(pending_cards) + 1243 predict_rs_scan_time_ms(scanned_cards) + 1244 predict_constant_other_time_ms(); 1245 } 1246 1247 double 1248 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) { 1249 size_t rs_length = predict_rs_length_diff(); 1250 size_t card_num; 1251 if (gcs_are_young()) { 1252 card_num = predict_young_card_num(rs_length); 1253 } else { 1254 card_num = predict_non_young_card_num(rs_length); 1255 } 1256 return predict_base_elapsed_time_ms(pending_cards, card_num); 1257 } 1258 1259 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) { 1260 size_t bytes_to_copy; 1261 if (hr->is_marked()) 1262 bytes_to_copy = hr->max_live_bytes(); 1263 else { 1264 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant"); 1265 int age = hr->age_in_surv_rate_group(); 1266 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); 1267 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate); 1268 } 1269 return bytes_to_copy; 1270 } 1271 1272 double 1273 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr, 1274 bool for_young_gc) { 1275 size_t rs_length = hr->rem_set()->occupied(); 1276 size_t card_num; 1277 1278 // Predicting the number of cards is based on which type of GC 1279 // we're predicting for. 1280 if (for_young_gc) { 1281 card_num = predict_young_card_num(rs_length); 1282 } else { 1283 card_num = predict_non_young_card_num(rs_length); 1284 } 1285 size_t bytes_to_copy = predict_bytes_to_copy(hr); 1286 1287 double region_elapsed_time_ms = 1288 predict_rs_scan_time_ms(card_num) + 1289 predict_object_copy_time_ms(bytes_to_copy); 1290 1291 // The prediction of the "other" time for this region is based 1292 // upon the region type and NOT the GC type. 1293 if (hr->is_young()) { 1294 region_elapsed_time_ms += predict_young_other_time_ms(1); 1295 } else { 1296 region_elapsed_time_ms += predict_non_young_other_time_ms(1); 1297 } 1298 return region_elapsed_time_ms; 1299 } 1300 1301 void 1302 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length, 1303 uint survivor_cset_region_length) { 1304 _eden_cset_region_length = eden_cset_region_length; 1305 _survivor_cset_region_length = survivor_cset_region_length; 1306 _old_cset_region_length = 0; 1307 } 1308 1309 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) { 1310 _recorded_rs_lengths = rs_lengths; 1311 } 1312 1313 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec, 1314 double elapsed_ms) { 1315 _recent_gc_times_ms->add(elapsed_ms); 1316 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec); 1317 _prev_collection_pause_end_ms = end_time_sec * 1000.0; 1318 } 1319 1320 size_t G1CollectorPolicy::expansion_amount() { 1321 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0; 1322 double threshold = _gc_overhead_perc; 1323 if (recent_gc_overhead > threshold) { 1324 // We will double the existing space, or take 1325 // G1ExpandByPercentOfAvailable % of the available expansion 1326 // space, whichever is smaller, bounded below by a minimum 1327 // expansion (unless that's all that's left.) 1328 const size_t min_expand_bytes = 1*M; 1329 size_t reserved_bytes = _g1->max_capacity(); 1330 size_t committed_bytes = _g1->capacity(); 1331 size_t uncommitted_bytes = reserved_bytes - committed_bytes; 1332 size_t expand_bytes; 1333 size_t expand_bytes_via_pct = 1334 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100; 1335 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes); 1336 expand_bytes = MAX2(expand_bytes, min_expand_bytes); 1337 expand_bytes = MIN2(expand_bytes, uncommitted_bytes); 1338 1339 ergo_verbose5(ErgoHeapSizing, 1340 "attempt heap expansion", 1341 ergo_format_reason("recent GC overhead higher than " 1342 "threshold after GC") 1343 ergo_format_perc("recent GC overhead") 1344 ergo_format_perc("threshold") 1345 ergo_format_byte("uncommitted") 1346 ergo_format_byte_perc("calculated expansion amount"), 1347 recent_gc_overhead, threshold, 1348 uncommitted_bytes, 1349 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable); 1350 1351 return expand_bytes; 1352 } else { 1353 return 0; 1354 } 1355 } 1356 1357 void G1CollectorPolicy::print_tracing_info() const { 1358 _trace_gen0_time_data.print(); 1359 _trace_gen1_time_data.print(); 1360 } 1361 1362 void G1CollectorPolicy::print_yg_surv_rate_info() const { 1363 #ifndef PRODUCT 1364 _short_lived_surv_rate_group->print_surv_rate_summary(); 1365 // add this call for any other surv rate groups 1366 #endif // PRODUCT 1367 } 1368 1369 #ifndef PRODUCT 1370 // for debugging, bit of a hack... 1371 static char* 1372 region_num_to_mbs(int length) { 1373 static char buffer[64]; 1374 double bytes = (double) (length * HeapRegion::GrainBytes); 1375 double mbs = bytes / (double) (1024 * 1024); 1376 sprintf(buffer, "%7.2lfMB", mbs); 1377 return buffer; 1378 } 1379 #endif // PRODUCT 1380 1381 uint G1CollectorPolicy::max_regions(int purpose) { 1382 switch (purpose) { 1383 case GCAllocForSurvived: 1384 return _max_survivor_regions; 1385 case GCAllocForTenured: 1386 return REGIONS_UNLIMITED; 1387 default: 1388 ShouldNotReachHere(); 1389 return REGIONS_UNLIMITED; 1390 }; 1391 } 1392 1393 void G1CollectorPolicy::update_max_gc_locker_expansion() { 1394 uint expansion_region_num = 0; 1395 if (GCLockerEdenExpansionPercent > 0) { 1396 double perc = (double) GCLockerEdenExpansionPercent / 100.0; 1397 double expansion_region_num_d = perc * (double) _young_list_target_length; 1398 // We use ceiling so that if expansion_region_num_d is > 0.0 (but 1399 // less than 1.0) we'll get 1. 1400 expansion_region_num = (uint) ceil(expansion_region_num_d); 1401 } else { 1402 assert(expansion_region_num == 0, "sanity"); 1403 } 1404 _young_list_max_length = _young_list_target_length + expansion_region_num; 1405 assert(_young_list_target_length <= _young_list_max_length, "post-condition"); 1406 } 1407 1408 // Calculates survivor space parameters. 1409 void G1CollectorPolicy::update_survivors_policy() { 1410 double max_survivor_regions_d = 1411 (double) _young_list_target_length / (double) SurvivorRatio; 1412 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but 1413 // smaller than 1.0) we'll get 1. 1414 _max_survivor_regions = (uint) ceil(max_survivor_regions_d); 1415 1416 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold( 1417 HeapRegion::GrainWords * _max_survivor_regions); 1418 } 1419 1420 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle( 1421 GCCause::Cause gc_cause) { 1422 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1423 if (!during_cycle) { 1424 ergo_verbose1(ErgoConcCycles, 1425 "request concurrent cycle initiation", 1426 ergo_format_reason("requested by GC cause") 1427 ergo_format_str("GC cause"), 1428 GCCause::to_string(gc_cause)); 1429 set_initiate_conc_mark_if_possible(); 1430 return true; 1431 } else { 1432 ergo_verbose1(ErgoConcCycles, 1433 "do not request concurrent cycle initiation", 1434 ergo_format_reason("concurrent cycle already in progress") 1435 ergo_format_str("GC cause"), 1436 GCCause::to_string(gc_cause)); 1437 return false; 1438 } 1439 } 1440 1441 void 1442 G1CollectorPolicy::decide_on_conc_mark_initiation() { 1443 // We are about to decide on whether this pause will be an 1444 // initial-mark pause. 1445 1446 // First, during_initial_mark_pause() should not be already set. We 1447 // will set it here if we have to. However, it should be cleared by 1448 // the end of the pause (it's only set for the duration of an 1449 // initial-mark pause). 1450 assert(!during_initial_mark_pause(), "pre-condition"); 1451 1452 if (initiate_conc_mark_if_possible()) { 1453 // We had noticed on a previous pause that the heap occupancy has 1454 // gone over the initiating threshold and we should start a 1455 // concurrent marking cycle. So we might initiate one. 1456 1457 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1458 if (!during_cycle) { 1459 // The concurrent marking thread is not "during a cycle", i.e., 1460 // it has completed the last one. So we can go ahead and 1461 // initiate a new cycle. 1462 1463 set_during_initial_mark_pause(); 1464 // We do not allow mixed GCs during marking. 1465 if (!gcs_are_young()) { 1466 set_gcs_are_young(true); 1467 ergo_verbose0(ErgoMixedGCs, 1468 "end mixed GCs", 1469 ergo_format_reason("concurrent cycle is about to start")); 1470 } 1471 1472 // And we can now clear initiate_conc_mark_if_possible() as 1473 // we've already acted on it. 1474 clear_initiate_conc_mark_if_possible(); 1475 1476 ergo_verbose0(ErgoConcCycles, 1477 "initiate concurrent cycle", 1478 ergo_format_reason("concurrent cycle initiation requested")); 1479 } else { 1480 // The concurrent marking thread is still finishing up the 1481 // previous cycle. If we start one right now the two cycles 1482 // overlap. In particular, the concurrent marking thread might 1483 // be in the process of clearing the next marking bitmap (which 1484 // we will use for the next cycle if we start one). Starting a 1485 // cycle now will be bad given that parts of the marking 1486 // information might get cleared by the marking thread. And we 1487 // cannot wait for the marking thread to finish the cycle as it 1488 // periodically yields while clearing the next marking bitmap 1489 // and, if it's in a yield point, it's waiting for us to 1490 // finish. So, at this point we will not start a cycle and we'll 1491 // let the concurrent marking thread complete the last one. 1492 ergo_verbose0(ErgoConcCycles, 1493 "do not initiate concurrent cycle", 1494 ergo_format_reason("concurrent cycle already in progress")); 1495 } 1496 } 1497 } 1498 1499 class KnownGarbageClosure: public HeapRegionClosure { 1500 G1CollectedHeap* _g1h; 1501 CollectionSetChooser* _hrSorted; 1502 1503 public: 1504 KnownGarbageClosure(CollectionSetChooser* hrSorted) : 1505 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { } 1506 1507 bool doHeapRegion(HeapRegion* r) { 1508 // We only include humongous regions in collection 1509 // sets when concurrent mark shows that their contained object is 1510 // unreachable. 1511 1512 // Do we have any marking information for this region? 1513 if (r->is_marked()) { 1514 // We will skip any region that's currently used as an old GC 1515 // alloc region (we should not consider those for collection 1516 // before we fill them up). 1517 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1518 _hrSorted->add_region(r); 1519 } 1520 } 1521 return false; 1522 } 1523 }; 1524 1525 class ParKnownGarbageHRClosure: public HeapRegionClosure { 1526 G1CollectedHeap* _g1h; 1527 CSetChooserParUpdater _cset_updater; 1528 1529 public: 1530 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted, 1531 uint chunk_size) : 1532 _g1h(G1CollectedHeap::heap()), 1533 _cset_updater(hrSorted, true /* parallel */, chunk_size) { } 1534 1535 bool doHeapRegion(HeapRegion* r) { 1536 // Do we have any marking information for this region? 1537 if (r->is_marked()) { 1538 // We will skip any region that's currently used as an old GC 1539 // alloc region (we should not consider those for collection 1540 // before we fill them up). 1541 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1542 _cset_updater.add_region(r); 1543 } 1544 } 1545 return false; 1546 } 1547 }; 1548 1549 class ParKnownGarbageTask: public AbstractGangTask { 1550 CollectionSetChooser* _hrSorted; 1551 uint _chunk_size; 1552 G1CollectedHeap* _g1; 1553 public: 1554 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) : 1555 AbstractGangTask("ParKnownGarbageTask"), 1556 _hrSorted(hrSorted), _chunk_size(chunk_size), 1557 _g1(G1CollectedHeap::heap()) { } 1558 1559 void work(uint worker_id) { 1560 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size); 1561 1562 // Back to zero for the claim value. 1563 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id, 1564 _g1->workers()->active_workers(), 1565 HeapRegion::InitialClaimValue); 1566 } 1567 }; 1568 1569 void 1570 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) { 1571 _collectionSetChooser->clear(); 1572 1573 uint region_num = _g1->n_regions(); 1574 if (G1CollectedHeap::use_parallel_gc_threads()) { 1575 const uint OverpartitionFactor = 4; 1576 uint WorkUnit; 1577 // The use of MinChunkSize = 8 in the original code 1578 // causes some assertion failures when the total number of 1579 // region is less than 8. The code here tries to fix that. 1580 // Should the original code also be fixed? 1581 if (no_of_gc_threads > 0) { 1582 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U); 1583 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor), 1584 MinWorkUnit); 1585 } else { 1586 assert(no_of_gc_threads > 0, 1587 "The active gc workers should be greater than 0"); 1588 // In a product build do something reasonable to avoid a crash. 1589 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U); 1590 WorkUnit = 1591 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor), 1592 MinWorkUnit); 1593 } 1594 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(), 1595 WorkUnit); 1596 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser, 1597 (int) WorkUnit); 1598 _g1->workers()->run_task(&parKnownGarbageTask); 1599 1600 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue), 1601 "sanity check"); 1602 } else { 1603 KnownGarbageClosure knownGarbagecl(_collectionSetChooser); 1604 _g1->heap_region_iterate(&knownGarbagecl); 1605 } 1606 1607 _collectionSetChooser->sort_regions(); 1608 1609 double end_sec = os::elapsedTime(); 1610 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; 1611 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms); 1612 _cur_mark_stop_world_time_ms += elapsed_time_ms; 1613 _prev_collection_pause_end_ms += elapsed_time_ms; 1614 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true); 1615 } 1616 1617 // Add the heap region at the head of the non-incremental collection set 1618 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) { 1619 assert(_inc_cset_build_state == Active, "Precondition"); 1620 assert(!hr->is_young(), "non-incremental add of young region"); 1621 1622 assert(!hr->in_collection_set(), "should not already be in the CSet"); 1623 hr->set_in_collection_set(true); 1624 hr->set_next_in_collection_set(_collection_set); 1625 _collection_set = hr; 1626 _collection_set_bytes_used_before += hr->used(); 1627 _g1->register_region_with_in_cset_fast_test(hr); 1628 size_t rs_length = hr->rem_set()->occupied(); 1629 _recorded_rs_lengths += rs_length; 1630 _old_cset_region_length += 1; 1631 } 1632 1633 // Initialize the per-collection-set information 1634 void G1CollectorPolicy::start_incremental_cset_building() { 1635 assert(_inc_cset_build_state == Inactive, "Precondition"); 1636 1637 _inc_cset_head = NULL; 1638 _inc_cset_tail = NULL; 1639 _inc_cset_bytes_used_before = 0; 1640 1641 _inc_cset_max_finger = 0; 1642 _inc_cset_recorded_rs_lengths = 0; 1643 _inc_cset_recorded_rs_lengths_diffs = 0; 1644 _inc_cset_predicted_elapsed_time_ms = 0.0; 1645 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1646 _inc_cset_build_state = Active; 1647 } 1648 1649 void G1CollectorPolicy::finalize_incremental_cset_building() { 1650 assert(_inc_cset_build_state == Active, "Precondition"); 1651 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 1652 1653 // The two "main" fields, _inc_cset_recorded_rs_lengths and 1654 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread 1655 // that adds a new region to the CSet. Further updates by the 1656 // concurrent refinement thread that samples the young RSet lengths 1657 // are accumulated in the *_diffs fields. Here we add the diffs to 1658 // the "main" fields. 1659 1660 if (_inc_cset_recorded_rs_lengths_diffs >= 0) { 1661 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs; 1662 } else { 1663 // This is defensive. The diff should in theory be always positive 1664 // as RSets can only grow between GCs. However, given that we 1665 // sample their size concurrently with other threads updating them 1666 // it's possible that we might get the wrong size back, which 1667 // could make the calculations somewhat inaccurate. 1668 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs); 1669 if (_inc_cset_recorded_rs_lengths >= diffs) { 1670 _inc_cset_recorded_rs_lengths -= diffs; 1671 } else { 1672 _inc_cset_recorded_rs_lengths = 0; 1673 } 1674 } 1675 _inc_cset_predicted_elapsed_time_ms += 1676 _inc_cset_predicted_elapsed_time_ms_diffs; 1677 1678 _inc_cset_recorded_rs_lengths_diffs = 0; 1679 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1680 } 1681 1682 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) { 1683 // This routine is used when: 1684 // * adding survivor regions to the incremental cset at the end of an 1685 // evacuation pause, 1686 // * adding the current allocation region to the incremental cset 1687 // when it is retired, and 1688 // * updating existing policy information for a region in the 1689 // incremental cset via young list RSet sampling. 1690 // Therefore this routine may be called at a safepoint by the 1691 // VM thread, or in-between safepoints by mutator threads (when 1692 // retiring the current allocation region) or a concurrent 1693 // refine thread (RSet sampling). 1694 1695 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 1696 size_t used_bytes = hr->used(); 1697 _inc_cset_recorded_rs_lengths += rs_length; 1698 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms; 1699 _inc_cset_bytes_used_before += used_bytes; 1700 1701 // Cache the values we have added to the aggregated informtion 1702 // in the heap region in case we have to remove this region from 1703 // the incremental collection set, or it is updated by the 1704 // rset sampling code 1705 hr->set_recorded_rs_length(rs_length); 1706 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms); 1707 } 1708 1709 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, 1710 size_t new_rs_length) { 1711 // Update the CSet information that is dependent on the new RS length 1712 assert(hr->is_young(), "Precondition"); 1713 assert(!SafepointSynchronize::is_at_safepoint(), 1714 "should not be at a safepoint"); 1715 1716 // We could have updated _inc_cset_recorded_rs_lengths and 1717 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do 1718 // that atomically, as this code is executed by a concurrent 1719 // refinement thread, potentially concurrently with a mutator thread 1720 // allocating a new region and also updating the same fields. To 1721 // avoid the atomic operations we accumulate these updates on two 1722 // separate fields (*_diffs) and we'll just add them to the "main" 1723 // fields at the start of a GC. 1724 1725 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length(); 1726 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length; 1727 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff; 1728 1729 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms(); 1730 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 1731 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms; 1732 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff; 1733 1734 hr->set_recorded_rs_length(new_rs_length); 1735 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms); 1736 } 1737 1738 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) { 1739 assert(hr->is_young(), "invariant"); 1740 assert(hr->young_index_in_cset() > -1, "should have already been set"); 1741 assert(_inc_cset_build_state == Active, "Precondition"); 1742 1743 // We need to clear and set the cached recorded/cached collection set 1744 // information in the heap region here (before the region gets added 1745 // to the collection set). An individual heap region's cached values 1746 // are calculated, aggregated with the policy collection set info, 1747 // and cached in the heap region here (initially) and (subsequently) 1748 // by the Young List sampling code. 1749 1750 size_t rs_length = hr->rem_set()->occupied(); 1751 add_to_incremental_cset_info(hr, rs_length); 1752 1753 HeapWord* hr_end = hr->end(); 1754 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end); 1755 1756 assert(!hr->in_collection_set(), "invariant"); 1757 hr->set_in_collection_set(true); 1758 assert( hr->next_in_collection_set() == NULL, "invariant"); 1759 1760 _g1->register_region_with_in_cset_fast_test(hr); 1761 } 1762 1763 // Add the region at the RHS of the incremental cset 1764 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) { 1765 // We should only ever be appending survivors at the end of a pause 1766 assert( hr->is_survivor(), "Logic"); 1767 1768 // Do the 'common' stuff 1769 add_region_to_incremental_cset_common(hr); 1770 1771 // Now add the region at the right hand side 1772 if (_inc_cset_tail == NULL) { 1773 assert(_inc_cset_head == NULL, "invariant"); 1774 _inc_cset_head = hr; 1775 } else { 1776 _inc_cset_tail->set_next_in_collection_set(hr); 1777 } 1778 _inc_cset_tail = hr; 1779 } 1780 1781 // Add the region to the LHS of the incremental cset 1782 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) { 1783 // Survivors should be added to the RHS at the end of a pause 1784 assert(!hr->is_survivor(), "Logic"); 1785 1786 // Do the 'common' stuff 1787 add_region_to_incremental_cset_common(hr); 1788 1789 // Add the region at the left hand side 1790 hr->set_next_in_collection_set(_inc_cset_head); 1791 if (_inc_cset_head == NULL) { 1792 assert(_inc_cset_tail == NULL, "Invariant"); 1793 _inc_cset_tail = hr; 1794 } 1795 _inc_cset_head = hr; 1796 } 1797 1798 #ifndef PRODUCT 1799 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) { 1800 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be"); 1801 1802 st->print_cr("\nCollection_set:"); 1803 HeapRegion* csr = list_head; 1804 while (csr != NULL) { 1805 HeapRegion* next = csr->next_in_collection_set(); 1806 assert(csr->in_collection_set(), "bad CS"); 1807 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 1808 HR_FORMAT_PARAMS(csr), 1809 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(), 1810 csr->age_in_surv_rate_group_cond()); 1811 csr = next; 1812 } 1813 } 1814 #endif // !PRODUCT 1815 1816 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) { 1817 // Returns the given amount of reclaimable bytes (that represents 1818 // the amount of reclaimable space still to be collected) as a 1819 // percentage of the current heap capacity. 1820 size_t capacity_bytes = _g1->capacity(); 1821 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes; 1822 } 1823 1824 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str, 1825 const char* false_action_str) { 1826 CollectionSetChooser* cset_chooser = _collectionSetChooser; 1827 if (cset_chooser->is_empty()) { 1828 ergo_verbose0(ErgoMixedGCs, 1829 false_action_str, 1830 ergo_format_reason("candidate old regions not available")); 1831 return false; 1832 } 1833 1834 // Is the amount of uncollected reclaimable space above G1HeapWastePercent? 1835 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 1836 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 1837 double threshold = (double) G1HeapWastePercent; 1838 if (reclaimable_perc <= threshold) { 1839 ergo_verbose4(ErgoMixedGCs, 1840 false_action_str, 1841 ergo_format_reason("reclaimable percentage not over threshold") 1842 ergo_format_region("candidate old regions") 1843 ergo_format_byte_perc("reclaimable") 1844 ergo_format_perc("threshold"), 1845 cset_chooser->remaining_regions(), 1846 reclaimable_bytes, 1847 reclaimable_perc, threshold); 1848 return false; 1849 } 1850 1851 ergo_verbose4(ErgoMixedGCs, 1852 true_action_str, 1853 ergo_format_reason("candidate old regions available") 1854 ergo_format_region("candidate old regions") 1855 ergo_format_byte_perc("reclaimable") 1856 ergo_format_perc("threshold"), 1857 cset_chooser->remaining_regions(), 1858 reclaimable_bytes, 1859 reclaimable_perc, threshold); 1860 return true; 1861 } 1862 1863 uint G1CollectorPolicy::calc_min_old_cset_length() { 1864 // The min old CSet region bound is based on the maximum desired 1865 // number of mixed GCs after a cycle. I.e., even if some old regions 1866 // look expensive, we should add them to the CSet anyway to make 1867 // sure we go through the available old regions in no more than the 1868 // maximum desired number of mixed GCs. 1869 // 1870 // The calculation is based on the number of marked regions we added 1871 // to the CSet chooser in the first place, not how many remain, so 1872 // that the result is the same during all mixed GCs that follow a cycle. 1873 1874 const size_t region_num = (size_t) _collectionSetChooser->length(); 1875 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); 1876 size_t result = region_num / gc_num; 1877 // emulate ceiling 1878 if (result * gc_num < region_num) { 1879 result += 1; 1880 } 1881 return (uint) result; 1882 } 1883 1884 uint G1CollectorPolicy::calc_max_old_cset_length() { 1885 // The max old CSet region bound is based on the threshold expressed 1886 // as a percentage of the heap size. I.e., it should bound the 1887 // number of old regions added to the CSet irrespective of how many 1888 // of them are available. 1889 1890 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1891 const size_t region_num = g1h->n_regions(); 1892 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; 1893 size_t result = region_num * perc / 100; 1894 // emulate ceiling 1895 if (100 * result < region_num * perc) { 1896 result += 1; 1897 } 1898 return (uint) result; 1899 } 1900 1901 1902 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) { 1903 double young_start_time_sec = os::elapsedTime(); 1904 1905 YoungList* young_list = _g1->young_list(); 1906 finalize_incremental_cset_building(); 1907 1908 guarantee(target_pause_time_ms > 0.0, 1909 err_msg("target_pause_time_ms = %1.6lf should be positive", 1910 target_pause_time_ms)); 1911 guarantee(_collection_set == NULL, "Precondition"); 1912 1913 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards); 1914 double predicted_pause_time_ms = base_time_ms; 1915 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0); 1916 1917 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 1918 "start choosing CSet", 1919 ergo_format_size("_pending_cards") 1920 ergo_format_ms("predicted base time") 1921 ergo_format_ms("remaining time") 1922 ergo_format_ms("target pause time"), 1923 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms); 1924 1925 _last_gc_was_young = gcs_are_young() ? true : false; 1926 1927 if (_last_gc_was_young) { 1928 _trace_gen0_time_data.increment_young_collection_count(); 1929 } else { 1930 _trace_gen0_time_data.increment_mixed_collection_count(); 1931 } 1932 1933 // The young list is laid with the survivor regions from the previous 1934 // pause are appended to the RHS of the young list, i.e. 1935 // [Newly Young Regions ++ Survivors from last pause]. 1936 1937 uint survivor_region_length = young_list->survivor_length(); 1938 uint eden_region_length = young_list->length() - survivor_region_length; 1939 init_cset_region_lengths(eden_region_length, survivor_region_length); 1940 1941 HeapRegion* hr = young_list->first_survivor_region(); 1942 while (hr != NULL) { 1943 assert(hr->is_survivor(), "badly formed young list"); 1944 hr->set_young(); 1945 hr = hr->get_next_young_region(); 1946 } 1947 1948 // Clear the fields that point to the survivor list - they are all young now. 1949 young_list->clear_survivors(); 1950 1951 _collection_set = _inc_cset_head; 1952 _collection_set_bytes_used_before = _inc_cset_bytes_used_before; 1953 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0); 1954 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms; 1955 1956 ergo_verbose3(ErgoCSetConstruction | ErgoHigh, 1957 "add young regions to CSet", 1958 ergo_format_region("eden") 1959 ergo_format_region("survivors") 1960 ergo_format_ms("predicted young region time"), 1961 eden_region_length, survivor_region_length, 1962 _inc_cset_predicted_elapsed_time_ms); 1963 1964 // The number of recorded young regions is the incremental 1965 // collection set's current size 1966 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths); 1967 1968 double young_end_time_sec = os::elapsedTime(); 1969 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0); 1970 1971 // Set the start of the non-young choice time. 1972 double non_young_start_time_sec = young_end_time_sec; 1973 1974 if (!gcs_are_young()) { 1975 CollectionSetChooser* cset_chooser = _collectionSetChooser; 1976 cset_chooser->verify(); 1977 const uint min_old_cset_length = calc_min_old_cset_length(); 1978 const uint max_old_cset_length = calc_max_old_cset_length(); 1979 1980 uint expensive_region_num = 0; 1981 bool check_time_remaining = adaptive_young_list_length(); 1982 1983 HeapRegion* hr = cset_chooser->peek(); 1984 while (hr != NULL) { 1985 if (old_cset_region_length() >= max_old_cset_length) { 1986 // Added maximum number of old regions to the CSet. 1987 ergo_verbose2(ErgoCSetConstruction, 1988 "finish adding old regions to CSet", 1989 ergo_format_reason("old CSet region num reached max") 1990 ergo_format_region("old") 1991 ergo_format_region("max"), 1992 old_cset_region_length(), max_old_cset_length); 1993 break; 1994 } 1995 1996 1997 // Stop adding regions if the remaining reclaimable space is 1998 // not above G1HeapWastePercent. 1999 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 2000 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 2001 double threshold = (double) G1HeapWastePercent; 2002 if (reclaimable_perc <= threshold) { 2003 // We've added enough old regions that the amount of uncollected 2004 // reclaimable space is at or below the waste threshold. Stop 2005 // adding old regions to the CSet. 2006 ergo_verbose5(ErgoCSetConstruction, 2007 "finish adding old regions to CSet", 2008 ergo_format_reason("reclaimable percentage not over threshold") 2009 ergo_format_region("old") 2010 ergo_format_region("max") 2011 ergo_format_byte_perc("reclaimable") 2012 ergo_format_perc("threshold"), 2013 old_cset_region_length(), 2014 max_old_cset_length, 2015 reclaimable_bytes, 2016 reclaimable_perc, threshold); 2017 break; 2018 } 2019 2020 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 2021 if (check_time_remaining) { 2022 if (predicted_time_ms > time_remaining_ms) { 2023 // Too expensive for the current CSet. 2024 2025 if (old_cset_region_length() >= min_old_cset_length) { 2026 // We have added the minimum number of old regions to the CSet, 2027 // we are done with this CSet. 2028 ergo_verbose4(ErgoCSetConstruction, 2029 "finish adding old regions to CSet", 2030 ergo_format_reason("predicted time is too high") 2031 ergo_format_ms("predicted time") 2032 ergo_format_ms("remaining time") 2033 ergo_format_region("old") 2034 ergo_format_region("min"), 2035 predicted_time_ms, time_remaining_ms, 2036 old_cset_region_length(), min_old_cset_length); 2037 break; 2038 } 2039 2040 // We'll add it anyway given that we haven't reached the 2041 // minimum number of old regions. 2042 expensive_region_num += 1; 2043 } 2044 } else { 2045 if (old_cset_region_length() >= min_old_cset_length) { 2046 // In the non-auto-tuning case, we'll finish adding regions 2047 // to the CSet if we reach the minimum. 2048 ergo_verbose2(ErgoCSetConstruction, 2049 "finish adding old regions to CSet", 2050 ergo_format_reason("old CSet region num reached min") 2051 ergo_format_region("old") 2052 ergo_format_region("min"), 2053 old_cset_region_length(), min_old_cset_length); 2054 break; 2055 } 2056 } 2057 2058 // We will add this region to the CSet. 2059 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); 2060 predicted_pause_time_ms += predicted_time_ms; 2061 cset_chooser->remove_and_move_to_next(hr); 2062 _g1->old_set_remove(hr); 2063 add_old_region_to_cset(hr); 2064 2065 hr = cset_chooser->peek(); 2066 } 2067 if (hr == NULL) { 2068 ergo_verbose0(ErgoCSetConstruction, 2069 "finish adding old regions to CSet", 2070 ergo_format_reason("candidate old regions not available")); 2071 } 2072 2073 if (expensive_region_num > 0) { 2074 // We print the information once here at the end, predicated on 2075 // whether we added any apparently expensive regions or not, to 2076 // avoid generating output per region. 2077 ergo_verbose4(ErgoCSetConstruction, 2078 "added expensive regions to CSet", 2079 ergo_format_reason("old CSet region num not reached min") 2080 ergo_format_region("old") 2081 ergo_format_region("expensive") 2082 ergo_format_region("min") 2083 ergo_format_ms("remaining time"), 2084 old_cset_region_length(), 2085 expensive_region_num, 2086 min_old_cset_length, 2087 time_remaining_ms); 2088 } 2089 2090 cset_chooser->verify(); 2091 } 2092 2093 stop_incremental_cset_building(); 2094 2095 ergo_verbose5(ErgoCSetConstruction, 2096 "finish choosing CSet", 2097 ergo_format_region("eden") 2098 ergo_format_region("survivors") 2099 ergo_format_region("old") 2100 ergo_format_ms("predicted pause time") 2101 ergo_format_ms("target pause time"), 2102 eden_region_length, survivor_region_length, 2103 old_cset_region_length(), 2104 predicted_pause_time_ms, target_pause_time_ms); 2105 2106 double non_young_end_time_sec = os::elapsedTime(); 2107 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); 2108 } 2109 2110 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) { 2111 if(TraceGen0Time) { 2112 _all_stop_world_times_ms.add(time_to_stop_the_world_ms); 2113 } 2114 } 2115 2116 void TraceGen0TimeData::record_yield_time(double yield_time_ms) { 2117 if(TraceGen0Time) { 2118 _all_yield_times_ms.add(yield_time_ms); 2119 } 2120 } 2121 2122 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) { 2123 if(TraceGen0Time) { 2124 _total.add(pause_time_ms); 2125 _other.add(pause_time_ms - phase_times->accounted_time_ms()); 2126 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms()); 2127 _parallel.add(phase_times->cur_collection_par_time_ms()); 2128 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time()); 2129 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms()); 2130 _update_rs.add(phase_times->average_last_update_rs_time()); 2131 _scan_rs.add(phase_times->average_last_scan_rs_time()); 2132 _obj_copy.add(phase_times->average_last_obj_copy_time()); 2133 _termination.add(phase_times->average_last_termination_time()); 2134 2135 double parallel_known_time = phase_times->average_last_ext_root_scan_time() + 2136 phase_times->average_last_satb_filtering_times_ms() + 2137 phase_times->average_last_update_rs_time() + 2138 phase_times->average_last_scan_rs_time() + 2139 phase_times->average_last_obj_copy_time() + 2140 + phase_times->average_last_termination_time(); 2141 2142 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time; 2143 _parallel_other.add(parallel_other_time); 2144 _clear_ct.add(phase_times->cur_clear_ct_time_ms()); 2145 } 2146 } 2147 2148 void TraceGen0TimeData::increment_young_collection_count() { 2149 if(TraceGen0Time) { 2150 ++_young_pause_num; 2151 } 2152 } 2153 2154 void TraceGen0TimeData::increment_mixed_collection_count() { 2155 if(TraceGen0Time) { 2156 ++_mixed_pause_num; 2157 } 2158 } 2159 2160 void TraceGen0TimeData::print_summary(const char* str, 2161 const NumberSeq* seq) const { 2162 double sum = seq->sum(); 2163 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)", 2164 str, sum / 1000.0, seq->avg()); 2165 } 2166 2167 void TraceGen0TimeData::print_summary_sd(const char* str, 2168 const NumberSeq* seq) const { 2169 print_summary(str, seq); 2170 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)", 2171 "(num", seq->num(), seq->sd(), seq->maximum()); 2172 } 2173 2174 void TraceGen0TimeData::print() const { 2175 if (!TraceGen0Time) { 2176 return; 2177 } 2178 2179 gclog_or_tty->print_cr("ALL PAUSES"); 2180 print_summary_sd(" Total", &_total); 2181 gclog_or_tty->print_cr(""); 2182 gclog_or_tty->print_cr(""); 2183 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num); 2184 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num); 2185 gclog_or_tty->print_cr(""); 2186 2187 gclog_or_tty->print_cr("EVACUATION PAUSES"); 2188 2189 if (_young_pause_num == 0 && _mixed_pause_num == 0) { 2190 gclog_or_tty->print_cr("none"); 2191 } else { 2192 print_summary_sd(" Evacuation Pauses", &_total); 2193 print_summary(" Root Region Scan Wait", &_root_region_scan_wait); 2194 print_summary(" Parallel Time", &_parallel); 2195 print_summary(" Ext Root Scanning", &_ext_root_scan); 2196 print_summary(" SATB Filtering", &_satb_filtering); 2197 print_summary(" Update RS", &_update_rs); 2198 print_summary(" Scan RS", &_scan_rs); 2199 print_summary(" Object Copy", &_obj_copy); 2200 print_summary(" Termination", &_termination); 2201 print_summary(" Parallel Other", &_parallel_other); 2202 print_summary(" Clear CT", &_clear_ct); 2203 print_summary(" Other", &_other); 2204 } 2205 gclog_or_tty->print_cr(""); 2206 2207 gclog_or_tty->print_cr("MISC"); 2208 print_summary_sd(" Stop World", &_all_stop_world_times_ms); 2209 print_summary_sd(" Yields", &_all_yield_times_ms); 2210 } 2211 2212 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) { 2213 if (TraceGen1Time) { 2214 _all_full_gc_times.add(full_gc_time_ms); 2215 } 2216 } 2217 2218 void TraceGen1TimeData::print() const { 2219 if (!TraceGen1Time) { 2220 return; 2221 } 2222 2223 if (_all_full_gc_times.num() > 0) { 2224 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s", 2225 _all_full_gc_times.num(), 2226 _all_full_gc_times.sum() / 1000.0); 2227 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg()); 2228 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]", 2229 _all_full_gc_times.sd(), 2230 _all_full_gc_times.maximum()); 2231 } 2232 }