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 _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes; 410 411 // We may immediately start allocating regions and placing them on the 412 // collection set list. Initialize the per-collection set info 413 start_incremental_cset_building(); 414 } 415 416 // Create the jstat counters for the policy. 417 void G1CollectorPolicy::initialize_gc_policy_counters() { 418 _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3); 419 } 420 421 bool G1CollectorPolicy::predict_will_fit(uint young_length, 422 double base_time_ms, 423 uint base_free_regions, 424 double target_pause_time_ms) { 425 if (young_length >= base_free_regions) { 426 // end condition 1: not enough space for the young regions 427 return false; 428 } 429 430 double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1); 431 size_t bytes_to_copy = 432 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); 433 double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy); 434 double young_other_time_ms = predict_young_other_time_ms(young_length); 435 double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms; 436 if (pause_time_ms > target_pause_time_ms) { 437 // end condition 2: prediction is over the target pause time 438 return false; 439 } 440 441 size_t free_bytes = 442 (base_free_regions - young_length) * HeapRegion::GrainBytes; 443 if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) { 444 // end condition 3: out-of-space (conservatively!) 445 return false; 446 } 447 448 // success! 449 return true; 450 } 451 452 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) { 453 // re-calculate the necessary reserve 454 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; 455 // We use ceiling so that if reserve_regions_d is > 0.0 (but 456 // smaller than 1.0) we'll get 1. 457 _reserve_regions = (uint) ceil(reserve_regions_d); 458 459 _young_gen_sizer->heap_size_changed(new_number_of_regions); 460 } 461 462 uint G1CollectorPolicy::calculate_young_list_desired_min_length( 463 uint base_min_length) { 464 uint desired_min_length = 0; 465 if (adaptive_young_list_length()) { 466 if (_alloc_rate_ms_seq->num() > 3) { 467 double now_sec = os::elapsedTime(); 468 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; 469 double alloc_rate_ms = predict_alloc_rate_ms(); 470 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); 471 } else { 472 // otherwise we don't have enough info to make the prediction 473 } 474 } 475 desired_min_length += base_min_length; 476 // make sure we don't go below any user-defined minimum bound 477 return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length); 478 } 479 480 uint G1CollectorPolicy::calculate_young_list_desired_max_length() { 481 // Here, we might want to also take into account any additional 482 // constraints (i.e., user-defined minimum bound). Currently, we 483 // effectively don't set this bound. 484 return _young_gen_sizer->max_desired_young_length(); 485 } 486 487 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) { 488 if (rs_lengths == (size_t) -1) { 489 // if it's set to the default value (-1), we should predict it; 490 // otherwise, use the given value. 491 rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq); 492 } 493 494 // Calculate the absolute and desired min bounds. 495 496 // This is how many young regions we already have (currently: the survivors). 497 uint base_min_length = recorded_survivor_regions(); 498 // This is the absolute minimum young length, which ensures that we 499 // can allocate one eden region in the worst-case. 500 uint absolute_min_length = base_min_length + 1; 501 uint desired_min_length = 502 calculate_young_list_desired_min_length(base_min_length); 503 if (desired_min_length < absolute_min_length) { 504 desired_min_length = absolute_min_length; 505 } 506 507 // Calculate the absolute and desired max bounds. 508 509 // We will try our best not to "eat" into the reserve. 510 uint absolute_max_length = 0; 511 if (_free_regions_at_end_of_collection > _reserve_regions) { 512 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; 513 } 514 uint desired_max_length = calculate_young_list_desired_max_length(); 515 if (desired_max_length > absolute_max_length) { 516 desired_max_length = absolute_max_length; 517 } 518 519 uint young_list_target_length = 0; 520 if (adaptive_young_list_length()) { 521 if (gcs_are_young()) { 522 young_list_target_length = 523 calculate_young_list_target_length(rs_lengths, 524 base_min_length, 525 desired_min_length, 526 desired_max_length); 527 _rs_lengths_prediction = rs_lengths; 528 } else { 529 // Don't calculate anything and let the code below bound it to 530 // the desired_min_length, i.e., do the next GC as soon as 531 // possible to maximize how many old regions we can add to it. 532 } 533 } else { 534 // The user asked for a fixed young gen so we'll fix the young gen 535 // whether the next GC is young or mixed. 536 young_list_target_length = _young_list_fixed_length; 537 } 538 539 // Make sure we don't go over the desired max length, nor under the 540 // desired min length. In case they clash, desired_min_length wins 541 // which is why that test is second. 542 if (young_list_target_length > desired_max_length) { 543 young_list_target_length = desired_max_length; 544 } 545 if (young_list_target_length < desired_min_length) { 546 young_list_target_length = desired_min_length; 547 } 548 549 assert(young_list_target_length > recorded_survivor_regions(), 550 "we should be able to allocate at least one eden region"); 551 assert(young_list_target_length >= absolute_min_length, "post-condition"); 552 _young_list_target_length = young_list_target_length; 553 554 update_max_gc_locker_expansion(); 555 } 556 557 uint 558 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths, 559 uint base_min_length, 560 uint desired_min_length, 561 uint desired_max_length) { 562 assert(adaptive_young_list_length(), "pre-condition"); 563 assert(gcs_are_young(), "only call this for young GCs"); 564 565 // In case some edge-condition makes the desired max length too small... 566 if (desired_max_length <= desired_min_length) { 567 return desired_min_length; 568 } 569 570 // We'll adjust min_young_length and max_young_length not to include 571 // the already allocated young regions (i.e., so they reflect the 572 // min and max eden regions we'll allocate). The base_min_length 573 // will be reflected in the predictions by the 574 // survivor_regions_evac_time prediction. 575 assert(desired_min_length > base_min_length, "invariant"); 576 uint min_young_length = desired_min_length - base_min_length; 577 assert(desired_max_length > base_min_length, "invariant"); 578 uint max_young_length = desired_max_length - base_min_length; 579 580 double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; 581 double survivor_regions_evac_time = predict_survivor_regions_evac_time(); 582 size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq); 583 size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff(); 584 size_t scanned_cards = predict_young_card_num(adj_rs_lengths); 585 double base_time_ms = 586 predict_base_elapsed_time_ms(pending_cards, scanned_cards) + 587 survivor_regions_evac_time; 588 uint available_free_regions = _free_regions_at_end_of_collection; 589 uint base_free_regions = 0; 590 if (available_free_regions > _reserve_regions) { 591 base_free_regions = available_free_regions - _reserve_regions; 592 } 593 594 // Here, we will make sure that the shortest young length that 595 // makes sense fits within the target pause time. 596 597 if (predict_will_fit(min_young_length, base_time_ms, 598 base_free_regions, target_pause_time_ms)) { 599 // The shortest young length will fit into the target pause time; 600 // we'll now check whether the absolute maximum number of young 601 // regions will fit in the target pause time. If not, we'll do 602 // a binary search between min_young_length and max_young_length. 603 if (predict_will_fit(max_young_length, base_time_ms, 604 base_free_regions, target_pause_time_ms)) { 605 // The maximum young length will fit into the target pause time. 606 // We are done so set min young length to the maximum length (as 607 // the result is assumed to be returned in min_young_length). 608 min_young_length = max_young_length; 609 } else { 610 // The maximum possible number of young regions will not fit within 611 // the target pause time so we'll search for the optimal 612 // length. The loop invariants are: 613 // 614 // min_young_length < max_young_length 615 // min_young_length is known to fit into the target pause time 616 // max_young_length is known not to fit into the target pause time 617 // 618 // Going into the loop we know the above hold as we've just 619 // checked them. Every time around the loop we check whether 620 // the middle value between min_young_length and 621 // max_young_length fits into the target pause time. If it 622 // does, it becomes the new min. If it doesn't, it becomes 623 // the new max. This way we maintain the loop invariants. 624 625 assert(min_young_length < max_young_length, "invariant"); 626 uint diff = (max_young_length - min_young_length) / 2; 627 while (diff > 0) { 628 uint young_length = min_young_length + diff; 629 if (predict_will_fit(young_length, base_time_ms, 630 base_free_regions, target_pause_time_ms)) { 631 min_young_length = young_length; 632 } else { 633 max_young_length = young_length; 634 } 635 assert(min_young_length < max_young_length, "invariant"); 636 diff = (max_young_length - min_young_length) / 2; 637 } 638 // The results is min_young_length which, according to the 639 // loop invariants, should fit within the target pause time. 640 641 // These are the post-conditions of the binary search above: 642 assert(min_young_length < max_young_length, 643 "otherwise we should have discovered that max_young_length " 644 "fits into the pause target and not done the binary search"); 645 assert(predict_will_fit(min_young_length, base_time_ms, 646 base_free_regions, target_pause_time_ms), 647 "min_young_length, the result of the binary search, should " 648 "fit into the pause target"); 649 assert(!predict_will_fit(min_young_length + 1, base_time_ms, 650 base_free_regions, target_pause_time_ms), 651 "min_young_length, the result of the binary search, should be " 652 "optimal, so no larger length should fit into the pause target"); 653 } 654 } else { 655 // Even the minimum length doesn't fit into the pause time 656 // target, return it as the result nevertheless. 657 } 658 return base_min_length + min_young_length; 659 } 660 661 double G1CollectorPolicy::predict_survivor_regions_evac_time() { 662 double survivor_regions_evac_time = 0.0; 663 for (HeapRegion * r = _recorded_survivor_head; 664 r != NULL && r != _recorded_survivor_tail->get_next_young_region(); 665 r = r->get_next_young_region()) { 666 survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young()); 667 } 668 return survivor_regions_evac_time; 669 } 670 671 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() { 672 guarantee( adaptive_young_list_length(), "should not call this otherwise" ); 673 674 size_t rs_lengths = _g1->young_list()->sampled_rs_lengths(); 675 if (rs_lengths > _rs_lengths_prediction) { 676 // add 10% to avoid having to recalculate often 677 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; 678 update_young_list_target_length(rs_lengths_prediction); 679 } 680 } 681 682 683 684 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size, 685 bool is_tlab, 686 bool* gc_overhead_limit_was_exceeded) { 687 guarantee(false, "Not using this policy feature yet."); 688 return NULL; 689 } 690 691 // This method controls how a collector handles one or more 692 // of its generations being fully allocated. 693 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size, 694 bool is_tlab) { 695 guarantee(false, "Not using this policy feature yet."); 696 return NULL; 697 } 698 699 700 #ifndef PRODUCT 701 bool G1CollectorPolicy::verify_young_ages() { 702 HeapRegion* head = _g1->young_list()->first_region(); 703 return 704 verify_young_ages(head, _short_lived_surv_rate_group); 705 // also call verify_young_ages on any additional surv rate groups 706 } 707 708 bool 709 G1CollectorPolicy::verify_young_ages(HeapRegion* head, 710 SurvRateGroup *surv_rate_group) { 711 guarantee( surv_rate_group != NULL, "pre-condition" ); 712 713 const char* name = surv_rate_group->name(); 714 bool ret = true; 715 int prev_age = -1; 716 717 for (HeapRegion* curr = head; 718 curr != NULL; 719 curr = curr->get_next_young_region()) { 720 SurvRateGroup* group = curr->surv_rate_group(); 721 if (group == NULL && !curr->is_survivor()) { 722 gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name); 723 ret = false; 724 } 725 726 if (surv_rate_group == group) { 727 int age = curr->age_in_surv_rate_group(); 728 729 if (age < 0) { 730 gclog_or_tty->print_cr("## %s: encountered negative age", name); 731 ret = false; 732 } 733 734 if (age <= prev_age) { 735 gclog_or_tty->print_cr("## %s: region ages are not strictly increasing " 736 "(%d, %d)", name, age, prev_age); 737 ret = false; 738 } 739 prev_age = age; 740 } 741 } 742 743 return ret; 744 } 745 #endif // PRODUCT 746 747 void G1CollectorPolicy::record_full_collection_start() { 748 _full_collection_start_sec = os::elapsedTime(); 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 size_t start_used) { 793 // We only need to do this here as the policy will only be applied 794 // to the GC we're about to start. so, no point is calculating this 795 // every time we calculate / recalculate the target young length. 796 update_survivors_policy(); 797 798 assert(_g1->used() == _g1->recalculate_used(), 799 err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT, 800 _g1->used(), _g1->recalculate_used())); 801 802 double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0; 803 _trace_gen0_time_data.record_start_collection(s_w_t_ms); 804 _stop_world_start = 0.0; 805 806 phase_times()->record_cur_collection_start_sec(start_time_sec); 807 _cur_collection_pause_used_at_start_bytes = start_used; 808 _cur_collection_pause_used_regions_at_start = _g1->used_regions(); 809 _pending_cards = _g1->pending_card_num(); 810 811 _collection_set_bytes_used_before = 0; 812 _bytes_copied_during_gc = 0; 813 814 YoungList* young_list = _g1->young_list(); 815 _eden_bytes_before_gc = young_list->eden_used_bytes(); 816 _survivor_bytes_before_gc = young_list->survivor_used_bytes(); 817 _capacity_before_gc = _g1->capacity(); 818 819 _last_gc_was_young = false; 820 821 // do that for any other surv rate groups 822 _short_lived_surv_rate_group->stop_adding_regions(); 823 _survivors_age_table.clear(); 824 825 assert( verify_young_ages(), "region age verification" ); 826 } 827 828 void G1CollectorPolicy::record_concurrent_mark_init_end(double 829 mark_init_elapsed_time_ms) { 830 _during_marking = true; 831 assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now"); 832 clear_during_initial_mark_pause(); 833 _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms; 834 } 835 836 void G1CollectorPolicy::record_concurrent_mark_remark_start() { 837 _mark_remark_start_sec = os::elapsedTime(); 838 _during_marking = false; 839 } 840 841 void G1CollectorPolicy::record_concurrent_mark_remark_end() { 842 double end_time_sec = os::elapsedTime(); 843 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; 844 _concurrent_mark_remark_times_ms->add(elapsed_time_ms); 845 _cur_mark_stop_world_time_ms += elapsed_time_ms; 846 _prev_collection_pause_end_ms += elapsed_time_ms; 847 848 _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true); 849 } 850 851 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() { 852 _mark_cleanup_start_sec = os::elapsedTime(); 853 } 854 855 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() { 856 _last_young_gc = true; 857 _in_marking_window = false; 858 } 859 860 void G1CollectorPolicy::record_concurrent_pause() { 861 if (_stop_world_start > 0.0) { 862 double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0; 863 _trace_gen0_time_data.record_yield_time(yield_ms); 864 } 865 } 866 867 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { 868 if (_g1->concurrent_mark()->cmThread()->during_cycle()) { 869 return false; 870 } 871 872 size_t marking_initiating_used_threshold = 873 (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent; 874 size_t cur_used_bytes = _g1->non_young_capacity_bytes(); 875 size_t alloc_byte_size = alloc_word_size * HeapWordSize; 876 877 if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) { 878 if (gcs_are_young()) { 879 ergo_verbose5(ErgoConcCycles, 880 "request concurrent cycle initiation", 881 ergo_format_reason("occupancy higher than threshold") 882 ergo_format_byte("occupancy") 883 ergo_format_byte("allocation request") 884 ergo_format_byte_perc("threshold") 885 ergo_format_str("source"), 886 cur_used_bytes, 887 alloc_byte_size, 888 marking_initiating_used_threshold, 889 (double) InitiatingHeapOccupancyPercent, 890 source); 891 return true; 892 } else { 893 ergo_verbose5(ErgoConcCycles, 894 "do not request concurrent cycle initiation", 895 ergo_format_reason("still doing mixed collections") 896 ergo_format_byte("occupancy") 897 ergo_format_byte("allocation request") 898 ergo_format_byte_perc("threshold") 899 ergo_format_str("source"), 900 cur_used_bytes, 901 alloc_byte_size, 902 marking_initiating_used_threshold, 903 (double) InitiatingHeapOccupancyPercent, 904 source); 905 } 906 } 907 908 return false; 909 } 910 911 // Anything below that is considered to be zero 912 #define MIN_TIMER_GRANULARITY 0.0000001 913 914 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) { 915 double end_time_sec = os::elapsedTime(); 916 assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(), 917 "otherwise, the subtraction below does not make sense"); 918 size_t rs_size = 919 _cur_collection_pause_used_regions_at_start - cset_region_length(); 920 size_t cur_used_bytes = _g1->used(); 921 assert(cur_used_bytes == _g1->recalculate_used(), "It should!"); 922 bool last_pause_included_initial_mark = false; 923 bool update_stats = !_g1->evacuation_failed(); 924 925 #ifndef PRODUCT 926 if (G1YoungSurvRateVerbose) { 927 gclog_or_tty->print_cr(""); 928 _short_lived_surv_rate_group->print(); 929 // do that for any other surv rate groups too 930 } 931 #endif // PRODUCT 932 933 last_pause_included_initial_mark = during_initial_mark_pause(); 934 if (last_pause_included_initial_mark) { 935 record_concurrent_mark_init_end(0.0); 936 } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) { 937 // Note: this might have already been set, if during the last 938 // pause we decided to start a cycle but at the beginning of 939 // this pause we decided to postpone it. That's OK. 940 set_initiate_conc_mark_if_possible(); 941 } 942 943 _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0, 944 end_time_sec, false); 945 946 size_t freed_bytes = 947 _cur_collection_pause_used_at_start_bytes - cur_used_bytes; 948 size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes; 949 950 double survival_fraction = 951 (double)surviving_bytes/ 952 (double)_collection_set_bytes_used_before; 953 954 evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before); 955 evacuation_info.set_bytes_copied(_bytes_copied_during_gc); 956 957 if (update_stats) { 958 _trace_gen0_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 bool new_in_marking_window = _in_marking_window; 1010 bool new_in_marking_window_im = false; 1011 if (during_initial_mark_pause()) { 1012 new_in_marking_window = true; 1013 new_in_marking_window_im = true; 1014 } 1015 1016 if (_last_young_gc) { 1017 // This is supposed to to be the "last young GC" before we start 1018 // doing mixed GCs. Here we decide whether to start mixed GCs or not. 1019 1020 if (!last_pause_included_initial_mark) { 1021 if (next_gc_should_be_mixed("start mixed GCs", 1022 "do not start mixed GCs")) { 1023 set_gcs_are_young(false); 1024 } 1025 } else { 1026 ergo_verbose0(ErgoMixedGCs, 1027 "do not start mixed GCs", 1028 ergo_format_reason("concurrent cycle is about to start")); 1029 } 1030 _last_young_gc = false; 1031 } 1032 1033 if (!_last_gc_was_young) { 1034 // This is a mixed GC. Here we decide whether to continue doing 1035 // mixed GCs or not. 1036 1037 if (!next_gc_should_be_mixed("continue mixed GCs", 1038 "do not continue mixed GCs")) { 1039 set_gcs_are_young(true); 1040 } 1041 } 1042 1043 _short_lived_surv_rate_group->start_adding_regions(); 1044 // do that for any other surv rate groupsx 1045 1046 if (update_stats) { 1047 double cost_per_card_ms = 0.0; 1048 if (_pending_cards > 0) { 1049 cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards; 1050 _cost_per_card_ms_seq->add(cost_per_card_ms); 1051 } 1052 1053 size_t cards_scanned = _g1->cards_scanned(); 1054 1055 double cost_per_entry_ms = 0.0; 1056 if (cards_scanned > 10) { 1057 cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned; 1058 if (_last_gc_was_young) { 1059 _cost_per_entry_ms_seq->add(cost_per_entry_ms); 1060 } else { 1061 _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms); 1062 } 1063 } 1064 1065 if (_max_rs_lengths > 0) { 1066 double cards_per_entry_ratio = 1067 (double) cards_scanned / (double) _max_rs_lengths; 1068 if (_last_gc_was_young) { 1069 _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1070 } else { 1071 _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio); 1072 } 1073 } 1074 1075 // This is defensive. For a while _max_rs_lengths could get 1076 // smaller than _recorded_rs_lengths which was causing 1077 // rs_length_diff to get very large and mess up the RSet length 1078 // predictions. The reason was unsafe concurrent updates to the 1079 // _inc_cset_recorded_rs_lengths field which the code below guards 1080 // against (see CR 7118202). This bug has now been fixed (see CR 1081 // 7119027). However, I'm still worried that 1082 // _inc_cset_recorded_rs_lengths might still end up somewhat 1083 // inaccurate. The concurrent refinement thread calculates an 1084 // RSet's length concurrently with other CR threads updating it 1085 // which might cause it to calculate the length incorrectly (if, 1086 // say, it's in mid-coarsening). So I'll leave in the defensive 1087 // conditional below just in case. 1088 size_t rs_length_diff = 0; 1089 if (_max_rs_lengths > _recorded_rs_lengths) { 1090 rs_length_diff = _max_rs_lengths - _recorded_rs_lengths; 1091 } 1092 _rs_length_diff_seq->add((double) rs_length_diff); 1093 1094 size_t copied_bytes = surviving_bytes; 1095 double cost_per_byte_ms = 0.0; 1096 if (copied_bytes > 0) { 1097 cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes; 1098 if (_in_marking_window) { 1099 _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms); 1100 } else { 1101 _cost_per_byte_ms_seq->add(cost_per_byte_ms); 1102 } 1103 } 1104 1105 double all_other_time_ms = pause_time_ms - 1106 (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time() 1107 + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time()); 1108 1109 double young_other_time_ms = 0.0; 1110 if (young_cset_region_length() > 0) { 1111 young_other_time_ms = 1112 phase_times()->young_cset_choice_time_ms() + 1113 phase_times()->young_free_cset_time_ms(); 1114 _young_other_cost_per_region_ms_seq->add(young_other_time_ms / 1115 (double) young_cset_region_length()); 1116 } 1117 double non_young_other_time_ms = 0.0; 1118 if (old_cset_region_length() > 0) { 1119 non_young_other_time_ms = 1120 phase_times()->non_young_cset_choice_time_ms() + 1121 phase_times()->non_young_free_cset_time_ms(); 1122 1123 _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms / 1124 (double) old_cset_region_length()); 1125 } 1126 1127 double constant_other_time_ms = all_other_time_ms - 1128 (young_other_time_ms + non_young_other_time_ms); 1129 _constant_other_time_ms_seq->add(constant_other_time_ms); 1130 1131 double survival_ratio = 0.0; 1132 if (_collection_set_bytes_used_before > 0) { 1133 survival_ratio = (double) _bytes_copied_during_gc / 1134 (double) _collection_set_bytes_used_before; 1135 } 1136 1137 _pending_cards_seq->add((double) _pending_cards); 1138 _rs_lengths_seq->add((double) _max_rs_lengths); 1139 } 1140 1141 _in_marking_window = new_in_marking_window; 1142 _in_marking_window_im = new_in_marking_window_im; 1143 _free_regions_at_end_of_collection = _g1->free_regions(); 1144 update_young_list_target_length(); 1145 1146 // Note that _mmu_tracker->max_gc_time() returns the time in seconds. 1147 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; 1148 adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(), 1149 phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms); 1150 1151 _collectionSetChooser->verify(); 1152 } 1153 1154 #define EXT_SIZE_FORMAT "%.1f%s" 1155 #define EXT_SIZE_PARAMS(bytes) \ 1156 byte_size_in_proper_unit((double)(bytes)), \ 1157 proper_unit_for_byte_size((bytes)) 1158 1159 void G1CollectorPolicy::print_heap_transition() { 1160 _g1->print_size_transition(gclog_or_tty, 1161 _cur_collection_pause_used_at_start_bytes, _g1->used(), _g1->capacity()); 1162 } 1163 1164 void G1CollectorPolicy::print_detailed_heap_transition() { 1165 YoungList* young_list = _g1->young_list(); 1166 size_t eden_bytes = young_list->eden_used_bytes(); 1167 size_t survivor_bytes = young_list->survivor_used_bytes(); 1168 size_t used_before_gc = _cur_collection_pause_used_at_start_bytes; 1169 size_t used = _g1->used(); 1170 size_t capacity = _g1->capacity(); 1171 size_t eden_capacity = 1172 (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes; 1173 1174 gclog_or_tty->print_cr( 1175 " [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") " 1176 "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" " 1177 "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->" 1178 EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]", 1179 EXT_SIZE_PARAMS(_eden_bytes_before_gc), 1180 EXT_SIZE_PARAMS(_prev_eden_capacity), 1181 EXT_SIZE_PARAMS(eden_bytes), 1182 EXT_SIZE_PARAMS(eden_capacity), 1183 EXT_SIZE_PARAMS(_survivor_bytes_before_gc), 1184 EXT_SIZE_PARAMS(survivor_bytes), 1185 EXT_SIZE_PARAMS(used_before_gc), 1186 EXT_SIZE_PARAMS(_capacity_before_gc), 1187 EXT_SIZE_PARAMS(used), 1188 EXT_SIZE_PARAMS(capacity)); 1189 1190 _prev_eden_capacity = eden_capacity; 1191 } 1192 1193 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time, 1194 double update_rs_processed_buffers, 1195 double goal_ms) { 1196 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1197 ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine(); 1198 1199 if (G1UseAdaptiveConcRefinement) { 1200 const int k_gy = 3, k_gr = 6; 1201 const double inc_k = 1.1, dec_k = 0.9; 1202 1203 int g = cg1r->green_zone(); 1204 if (update_rs_time > goal_ms) { 1205 g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing. 1206 } else { 1207 if (update_rs_time < goal_ms && update_rs_processed_buffers > g) { 1208 g = (int)MAX2(g * inc_k, g + 1.0); 1209 } 1210 } 1211 // Change the refinement threads params 1212 cg1r->set_green_zone(g); 1213 cg1r->set_yellow_zone(g * k_gy); 1214 cg1r->set_red_zone(g * k_gr); 1215 cg1r->reinitialize_threads(); 1216 1217 int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1); 1218 int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta, 1219 cg1r->yellow_zone()); 1220 // Change the barrier params 1221 dcqs.set_process_completed_threshold(processing_threshold); 1222 dcqs.set_max_completed_queue(cg1r->red_zone()); 1223 } 1224 1225 int curr_queue_size = dcqs.completed_buffers_num(); 1226 if (curr_queue_size >= cg1r->yellow_zone()) { 1227 dcqs.set_completed_queue_padding(curr_queue_size); 1228 } else { 1229 dcqs.set_completed_queue_padding(0); 1230 } 1231 dcqs.notify_if_necessary(); 1232 } 1233 1234 double 1235 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards, 1236 size_t scanned_cards) { 1237 return 1238 predict_rs_update_time_ms(pending_cards) + 1239 predict_rs_scan_time_ms(scanned_cards) + 1240 predict_constant_other_time_ms(); 1241 } 1242 1243 double 1244 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) { 1245 size_t rs_length = predict_rs_length_diff(); 1246 size_t card_num; 1247 if (gcs_are_young()) { 1248 card_num = predict_young_card_num(rs_length); 1249 } else { 1250 card_num = predict_non_young_card_num(rs_length); 1251 } 1252 return predict_base_elapsed_time_ms(pending_cards, card_num); 1253 } 1254 1255 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) { 1256 size_t bytes_to_copy; 1257 if (hr->is_marked()) 1258 bytes_to_copy = hr->max_live_bytes(); 1259 else { 1260 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant"); 1261 int age = hr->age_in_surv_rate_group(); 1262 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); 1263 bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate); 1264 } 1265 return bytes_to_copy; 1266 } 1267 1268 double 1269 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr, 1270 bool for_young_gc) { 1271 size_t rs_length = hr->rem_set()->occupied(); 1272 size_t card_num; 1273 1274 // Predicting the number of cards is based on which type of GC 1275 // we're predicting for. 1276 if (for_young_gc) { 1277 card_num = predict_young_card_num(rs_length); 1278 } else { 1279 card_num = predict_non_young_card_num(rs_length); 1280 } 1281 size_t bytes_to_copy = predict_bytes_to_copy(hr); 1282 1283 double region_elapsed_time_ms = 1284 predict_rs_scan_time_ms(card_num) + 1285 predict_object_copy_time_ms(bytes_to_copy); 1286 1287 // The prediction of the "other" time for this region is based 1288 // upon the region type and NOT the GC type. 1289 if (hr->is_young()) { 1290 region_elapsed_time_ms += predict_young_other_time_ms(1); 1291 } else { 1292 region_elapsed_time_ms += predict_non_young_other_time_ms(1); 1293 } 1294 return region_elapsed_time_ms; 1295 } 1296 1297 void 1298 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length, 1299 uint survivor_cset_region_length) { 1300 _eden_cset_region_length = eden_cset_region_length; 1301 _survivor_cset_region_length = survivor_cset_region_length; 1302 _old_cset_region_length = 0; 1303 } 1304 1305 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) { 1306 _recorded_rs_lengths = rs_lengths; 1307 } 1308 1309 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec, 1310 double elapsed_ms) { 1311 _recent_gc_times_ms->add(elapsed_ms); 1312 _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec); 1313 _prev_collection_pause_end_ms = end_time_sec * 1000.0; 1314 } 1315 1316 size_t G1CollectorPolicy::expansion_amount() { 1317 double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0; 1318 double threshold = _gc_overhead_perc; 1319 if (recent_gc_overhead > threshold) { 1320 // We will double the existing space, or take 1321 // G1ExpandByPercentOfAvailable % of the available expansion 1322 // space, whichever is smaller, bounded below by a minimum 1323 // expansion (unless that's all that's left.) 1324 const size_t min_expand_bytes = 1*M; 1325 size_t reserved_bytes = _g1->max_capacity(); 1326 size_t committed_bytes = _g1->capacity(); 1327 size_t uncommitted_bytes = reserved_bytes - committed_bytes; 1328 size_t expand_bytes; 1329 size_t expand_bytes_via_pct = 1330 uncommitted_bytes * G1ExpandByPercentOfAvailable / 100; 1331 expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes); 1332 expand_bytes = MAX2(expand_bytes, min_expand_bytes); 1333 expand_bytes = MIN2(expand_bytes, uncommitted_bytes); 1334 1335 ergo_verbose5(ErgoHeapSizing, 1336 "attempt heap expansion", 1337 ergo_format_reason("recent GC overhead higher than " 1338 "threshold after GC") 1339 ergo_format_perc("recent GC overhead") 1340 ergo_format_perc("threshold") 1341 ergo_format_byte("uncommitted") 1342 ergo_format_byte_perc("calculated expansion amount"), 1343 recent_gc_overhead, threshold, 1344 uncommitted_bytes, 1345 expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable); 1346 1347 return expand_bytes; 1348 } else { 1349 return 0; 1350 } 1351 } 1352 1353 void G1CollectorPolicy::print_tracing_info() const { 1354 _trace_gen0_time_data.print(); 1355 _trace_gen1_time_data.print(); 1356 } 1357 1358 void G1CollectorPolicy::print_yg_surv_rate_info() const { 1359 #ifndef PRODUCT 1360 _short_lived_surv_rate_group->print_surv_rate_summary(); 1361 // add this call for any other surv rate groups 1362 #endif // PRODUCT 1363 } 1364 1365 #ifndef PRODUCT 1366 // for debugging, bit of a hack... 1367 static char* 1368 region_num_to_mbs(int length) { 1369 static char buffer[64]; 1370 double bytes = (double) (length * HeapRegion::GrainBytes); 1371 double mbs = bytes / (double) (1024 * 1024); 1372 sprintf(buffer, "%7.2lfMB", mbs); 1373 return buffer; 1374 } 1375 #endif // PRODUCT 1376 1377 uint G1CollectorPolicy::max_regions(int purpose) { 1378 switch (purpose) { 1379 case GCAllocForSurvived: 1380 return _max_survivor_regions; 1381 case GCAllocForTenured: 1382 return REGIONS_UNLIMITED; 1383 default: 1384 ShouldNotReachHere(); 1385 return REGIONS_UNLIMITED; 1386 }; 1387 } 1388 1389 void G1CollectorPolicy::update_max_gc_locker_expansion() { 1390 uint expansion_region_num = 0; 1391 if (GCLockerEdenExpansionPercent > 0) { 1392 double perc = (double) GCLockerEdenExpansionPercent / 100.0; 1393 double expansion_region_num_d = perc * (double) _young_list_target_length; 1394 // We use ceiling so that if expansion_region_num_d is > 0.0 (but 1395 // less than 1.0) we'll get 1. 1396 expansion_region_num = (uint) ceil(expansion_region_num_d); 1397 } else { 1398 assert(expansion_region_num == 0, "sanity"); 1399 } 1400 _young_list_max_length = _young_list_target_length + expansion_region_num; 1401 assert(_young_list_target_length <= _young_list_max_length, "post-condition"); 1402 } 1403 1404 // Calculates survivor space parameters. 1405 void G1CollectorPolicy::update_survivors_policy() { 1406 double max_survivor_regions_d = 1407 (double) _young_list_target_length / (double) SurvivorRatio; 1408 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but 1409 // smaller than 1.0) we'll get 1. 1410 _max_survivor_regions = (uint) ceil(max_survivor_regions_d); 1411 1412 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold( 1413 HeapRegion::GrainWords * _max_survivor_regions); 1414 } 1415 1416 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle( 1417 GCCause::Cause gc_cause) { 1418 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1419 if (!during_cycle) { 1420 ergo_verbose1(ErgoConcCycles, 1421 "request concurrent cycle initiation", 1422 ergo_format_reason("requested by GC cause") 1423 ergo_format_str("GC cause"), 1424 GCCause::to_string(gc_cause)); 1425 set_initiate_conc_mark_if_possible(); 1426 return true; 1427 } else { 1428 ergo_verbose1(ErgoConcCycles, 1429 "do not request concurrent cycle initiation", 1430 ergo_format_reason("concurrent cycle already in progress") 1431 ergo_format_str("GC cause"), 1432 GCCause::to_string(gc_cause)); 1433 return false; 1434 } 1435 } 1436 1437 void 1438 G1CollectorPolicy::decide_on_conc_mark_initiation() { 1439 // We are about to decide on whether this pause will be an 1440 // initial-mark pause. 1441 1442 // First, during_initial_mark_pause() should not be already set. We 1443 // will set it here if we have to. However, it should be cleared by 1444 // the end of the pause (it's only set for the duration of an 1445 // initial-mark pause). 1446 assert(!during_initial_mark_pause(), "pre-condition"); 1447 1448 if (initiate_conc_mark_if_possible()) { 1449 // We had noticed on a previous pause that the heap occupancy has 1450 // gone over the initiating threshold and we should start a 1451 // concurrent marking cycle. So we might initiate one. 1452 1453 bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle(); 1454 if (!during_cycle) { 1455 // The concurrent marking thread is not "during a cycle", i.e., 1456 // it has completed the last one. So we can go ahead and 1457 // initiate a new cycle. 1458 1459 set_during_initial_mark_pause(); 1460 // We do not allow mixed GCs during marking. 1461 if (!gcs_are_young()) { 1462 set_gcs_are_young(true); 1463 ergo_verbose0(ErgoMixedGCs, 1464 "end mixed GCs", 1465 ergo_format_reason("concurrent cycle is about to start")); 1466 } 1467 1468 // And we can now clear initiate_conc_mark_if_possible() as 1469 // we've already acted on it. 1470 clear_initiate_conc_mark_if_possible(); 1471 1472 ergo_verbose0(ErgoConcCycles, 1473 "initiate concurrent cycle", 1474 ergo_format_reason("concurrent cycle initiation requested")); 1475 } else { 1476 // The concurrent marking thread is still finishing up the 1477 // previous cycle. If we start one right now the two cycles 1478 // overlap. In particular, the concurrent marking thread might 1479 // be in the process of clearing the next marking bitmap (which 1480 // we will use for the next cycle if we start one). Starting a 1481 // cycle now will be bad given that parts of the marking 1482 // information might get cleared by the marking thread. And we 1483 // cannot wait for the marking thread to finish the cycle as it 1484 // periodically yields while clearing the next marking bitmap 1485 // and, if it's in a yield point, it's waiting for us to 1486 // finish. So, at this point we will not start a cycle and we'll 1487 // let the concurrent marking thread complete the last one. 1488 ergo_verbose0(ErgoConcCycles, 1489 "do not initiate concurrent cycle", 1490 ergo_format_reason("concurrent cycle already in progress")); 1491 } 1492 } 1493 } 1494 1495 class KnownGarbageClosure: public HeapRegionClosure { 1496 G1CollectedHeap* _g1h; 1497 CollectionSetChooser* _hrSorted; 1498 1499 public: 1500 KnownGarbageClosure(CollectionSetChooser* hrSorted) : 1501 _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { } 1502 1503 bool doHeapRegion(HeapRegion* r) { 1504 // We only include humongous regions in collection 1505 // sets when concurrent mark shows that their contained object is 1506 // unreachable. 1507 1508 // Do we have any marking information for this region? 1509 if (r->is_marked()) { 1510 // We will skip any region that's currently used as an old GC 1511 // alloc region (we should not consider those for collection 1512 // before we fill them up). 1513 if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1514 _hrSorted->add_region(r); 1515 } 1516 } 1517 return false; 1518 } 1519 }; 1520 1521 class ParKnownGarbageHRClosure: public HeapRegionClosure { 1522 G1CollectedHeap* _g1h; 1523 CSetChooserParUpdater _cset_updater; 1524 1525 public: 1526 ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted, 1527 uint chunk_size) : 1528 _g1h(G1CollectedHeap::heap()), 1529 _cset_updater(hrSorted, true /* parallel */, chunk_size) { } 1530 1531 bool doHeapRegion(HeapRegion* r) { 1532 // Do we have any marking information for this region? 1533 if (r->is_marked()) { 1534 // We will skip any region that's currently used as an old GC 1535 // alloc region (we should not consider those for collection 1536 // before we fill them up). 1537 if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) { 1538 _cset_updater.add_region(r); 1539 } 1540 } 1541 return false; 1542 } 1543 }; 1544 1545 class ParKnownGarbageTask: public AbstractGangTask { 1546 CollectionSetChooser* _hrSorted; 1547 uint _chunk_size; 1548 G1CollectedHeap* _g1; 1549 public: 1550 ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) : 1551 AbstractGangTask("ParKnownGarbageTask"), 1552 _hrSorted(hrSorted), _chunk_size(chunk_size), 1553 _g1(G1CollectedHeap::heap()) { } 1554 1555 void work(uint worker_id) { 1556 ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size); 1557 1558 // Back to zero for the claim value. 1559 _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id, 1560 _g1->workers()->active_workers(), 1561 HeapRegion::InitialClaimValue); 1562 } 1563 }; 1564 1565 void 1566 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) { 1567 _collectionSetChooser->clear(); 1568 1569 uint region_num = _g1->n_regions(); 1570 if (G1CollectedHeap::use_parallel_gc_threads()) { 1571 const uint OverpartitionFactor = 4; 1572 uint WorkUnit; 1573 // The use of MinChunkSize = 8 in the original code 1574 // causes some assertion failures when the total number of 1575 // region is less than 8. The code here tries to fix that. 1576 // Should the original code also be fixed? 1577 if (no_of_gc_threads > 0) { 1578 const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U); 1579 WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor), 1580 MinWorkUnit); 1581 } else { 1582 assert(no_of_gc_threads > 0, 1583 "The active gc workers should be greater than 0"); 1584 // In a product build do something reasonable to avoid a crash. 1585 const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U); 1586 WorkUnit = 1587 MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor), 1588 MinWorkUnit); 1589 } 1590 _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(), 1591 WorkUnit); 1592 ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser, 1593 (int) WorkUnit); 1594 _g1->workers()->run_task(&parKnownGarbageTask); 1595 1596 assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue), 1597 "sanity check"); 1598 } else { 1599 KnownGarbageClosure knownGarbagecl(_collectionSetChooser); 1600 _g1->heap_region_iterate(&knownGarbagecl); 1601 } 1602 1603 _collectionSetChooser->sort_regions(); 1604 1605 double end_sec = os::elapsedTime(); 1606 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; 1607 _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms); 1608 _cur_mark_stop_world_time_ms += elapsed_time_ms; 1609 _prev_collection_pause_end_ms += elapsed_time_ms; 1610 _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true); 1611 } 1612 1613 // Add the heap region at the head of the non-incremental collection set 1614 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) { 1615 assert(_inc_cset_build_state == Active, "Precondition"); 1616 assert(!hr->is_young(), "non-incremental add of young region"); 1617 1618 assert(!hr->in_collection_set(), "should not already be in the CSet"); 1619 hr->set_in_collection_set(true); 1620 hr->set_next_in_collection_set(_collection_set); 1621 _collection_set = hr; 1622 _collection_set_bytes_used_before += hr->used(); 1623 _g1->register_region_with_in_cset_fast_test(hr); 1624 size_t rs_length = hr->rem_set()->occupied(); 1625 _recorded_rs_lengths += rs_length; 1626 _old_cset_region_length += 1; 1627 } 1628 1629 // Initialize the per-collection-set information 1630 void G1CollectorPolicy::start_incremental_cset_building() { 1631 assert(_inc_cset_build_state == Inactive, "Precondition"); 1632 1633 _inc_cset_head = NULL; 1634 _inc_cset_tail = NULL; 1635 _inc_cset_bytes_used_before = 0; 1636 1637 _inc_cset_max_finger = 0; 1638 _inc_cset_recorded_rs_lengths = 0; 1639 _inc_cset_recorded_rs_lengths_diffs = 0; 1640 _inc_cset_predicted_elapsed_time_ms = 0.0; 1641 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1642 _inc_cset_build_state = Active; 1643 } 1644 1645 void G1CollectorPolicy::finalize_incremental_cset_building() { 1646 assert(_inc_cset_build_state == Active, "Precondition"); 1647 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 1648 1649 // The two "main" fields, _inc_cset_recorded_rs_lengths and 1650 // _inc_cset_predicted_elapsed_time_ms, are updated by the thread 1651 // that adds a new region to the CSet. Further updates by the 1652 // concurrent refinement thread that samples the young RSet lengths 1653 // are accumulated in the *_diffs fields. Here we add the diffs to 1654 // the "main" fields. 1655 1656 if (_inc_cset_recorded_rs_lengths_diffs >= 0) { 1657 _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs; 1658 } else { 1659 // This is defensive. The diff should in theory be always positive 1660 // as RSets can only grow between GCs. However, given that we 1661 // sample their size concurrently with other threads updating them 1662 // it's possible that we might get the wrong size back, which 1663 // could make the calculations somewhat inaccurate. 1664 size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs); 1665 if (_inc_cset_recorded_rs_lengths >= diffs) { 1666 _inc_cset_recorded_rs_lengths -= diffs; 1667 } else { 1668 _inc_cset_recorded_rs_lengths = 0; 1669 } 1670 } 1671 _inc_cset_predicted_elapsed_time_ms += 1672 _inc_cset_predicted_elapsed_time_ms_diffs; 1673 1674 _inc_cset_recorded_rs_lengths_diffs = 0; 1675 _inc_cset_predicted_elapsed_time_ms_diffs = 0.0; 1676 } 1677 1678 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) { 1679 // This routine is used when: 1680 // * adding survivor regions to the incremental cset at the end of an 1681 // evacuation pause, 1682 // * adding the current allocation region to the incremental cset 1683 // when it is retired, and 1684 // * updating existing policy information for a region in the 1685 // incremental cset via young list RSet sampling. 1686 // Therefore this routine may be called at a safepoint by the 1687 // VM thread, or in-between safepoints by mutator threads (when 1688 // retiring the current allocation region) or a concurrent 1689 // refine thread (RSet sampling). 1690 1691 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 1692 size_t used_bytes = hr->used(); 1693 _inc_cset_recorded_rs_lengths += rs_length; 1694 _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms; 1695 _inc_cset_bytes_used_before += used_bytes; 1696 1697 // Cache the values we have added to the aggregated informtion 1698 // in the heap region in case we have to remove this region from 1699 // the incremental collection set, or it is updated by the 1700 // rset sampling code 1701 hr->set_recorded_rs_length(rs_length); 1702 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms); 1703 } 1704 1705 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, 1706 size_t new_rs_length) { 1707 // Update the CSet information that is dependent on the new RS length 1708 assert(hr->is_young(), "Precondition"); 1709 assert(!SafepointSynchronize::is_at_safepoint(), 1710 "should not be at a safepoint"); 1711 1712 // We could have updated _inc_cset_recorded_rs_lengths and 1713 // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do 1714 // that atomically, as this code is executed by a concurrent 1715 // refinement thread, potentially concurrently with a mutator thread 1716 // allocating a new region and also updating the same fields. To 1717 // avoid the atomic operations we accumulate these updates on two 1718 // separate fields (*_diffs) and we'll just add them to the "main" 1719 // fields at the start of a GC. 1720 1721 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length(); 1722 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length; 1723 _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff; 1724 1725 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms(); 1726 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 1727 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms; 1728 _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff; 1729 1730 hr->set_recorded_rs_length(new_rs_length); 1731 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms); 1732 } 1733 1734 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) { 1735 assert(hr->is_young(), "invariant"); 1736 assert(hr->young_index_in_cset() > -1, "should have already been set"); 1737 assert(_inc_cset_build_state == Active, "Precondition"); 1738 1739 // We need to clear and set the cached recorded/cached collection set 1740 // information in the heap region here (before the region gets added 1741 // to the collection set). An individual heap region's cached values 1742 // are calculated, aggregated with the policy collection set info, 1743 // and cached in the heap region here (initially) and (subsequently) 1744 // by the Young List sampling code. 1745 1746 size_t rs_length = hr->rem_set()->occupied(); 1747 add_to_incremental_cset_info(hr, rs_length); 1748 1749 HeapWord* hr_end = hr->end(); 1750 _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end); 1751 1752 assert(!hr->in_collection_set(), "invariant"); 1753 hr->set_in_collection_set(true); 1754 assert( hr->next_in_collection_set() == NULL, "invariant"); 1755 1756 _g1->register_region_with_in_cset_fast_test(hr); 1757 } 1758 1759 // Add the region at the RHS of the incremental cset 1760 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) { 1761 // We should only ever be appending survivors at the end of a pause 1762 assert( hr->is_survivor(), "Logic"); 1763 1764 // Do the 'common' stuff 1765 add_region_to_incremental_cset_common(hr); 1766 1767 // Now add the region at the right hand side 1768 if (_inc_cset_tail == NULL) { 1769 assert(_inc_cset_head == NULL, "invariant"); 1770 _inc_cset_head = hr; 1771 } else { 1772 _inc_cset_tail->set_next_in_collection_set(hr); 1773 } 1774 _inc_cset_tail = hr; 1775 } 1776 1777 // Add the region to the LHS of the incremental cset 1778 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) { 1779 // Survivors should be added to the RHS at the end of a pause 1780 assert(!hr->is_survivor(), "Logic"); 1781 1782 // Do the 'common' stuff 1783 add_region_to_incremental_cset_common(hr); 1784 1785 // Add the region at the left hand side 1786 hr->set_next_in_collection_set(_inc_cset_head); 1787 if (_inc_cset_head == NULL) { 1788 assert(_inc_cset_tail == NULL, "Invariant"); 1789 _inc_cset_tail = hr; 1790 } 1791 _inc_cset_head = hr; 1792 } 1793 1794 #ifndef PRODUCT 1795 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) { 1796 assert(list_head == inc_cset_head() || list_head == collection_set(), "must be"); 1797 1798 st->print_cr("\nCollection_set:"); 1799 HeapRegion* csr = list_head; 1800 while (csr != NULL) { 1801 HeapRegion* next = csr->next_in_collection_set(); 1802 assert(csr->in_collection_set(), "bad CS"); 1803 st->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 1804 HR_FORMAT_PARAMS(csr), 1805 csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(), 1806 csr->age_in_surv_rate_group_cond()); 1807 csr = next; 1808 } 1809 } 1810 #endif // !PRODUCT 1811 1812 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) { 1813 // Returns the given amount of reclaimable bytes (that represents 1814 // the amount of reclaimable space still to be collected) as a 1815 // percentage of the current heap capacity. 1816 size_t capacity_bytes = _g1->capacity(); 1817 return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes; 1818 } 1819 1820 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str, 1821 const char* false_action_str) { 1822 CollectionSetChooser* cset_chooser = _collectionSetChooser; 1823 if (cset_chooser->is_empty()) { 1824 ergo_verbose0(ErgoMixedGCs, 1825 false_action_str, 1826 ergo_format_reason("candidate old regions not available")); 1827 return false; 1828 } 1829 1830 // Is the amount of uncollected reclaimable space above G1HeapWastePercent? 1831 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 1832 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 1833 double threshold = (double) G1HeapWastePercent; 1834 if (reclaimable_perc <= threshold) { 1835 ergo_verbose4(ErgoMixedGCs, 1836 false_action_str, 1837 ergo_format_reason("reclaimable percentage not over threshold") 1838 ergo_format_region("candidate old regions") 1839 ergo_format_byte_perc("reclaimable") 1840 ergo_format_perc("threshold"), 1841 cset_chooser->remaining_regions(), 1842 reclaimable_bytes, 1843 reclaimable_perc, threshold); 1844 return false; 1845 } 1846 1847 ergo_verbose4(ErgoMixedGCs, 1848 true_action_str, 1849 ergo_format_reason("candidate old regions available") 1850 ergo_format_region("candidate old regions") 1851 ergo_format_byte_perc("reclaimable") 1852 ergo_format_perc("threshold"), 1853 cset_chooser->remaining_regions(), 1854 reclaimable_bytes, 1855 reclaimable_perc, threshold); 1856 return true; 1857 } 1858 1859 uint G1CollectorPolicy::calc_min_old_cset_length() { 1860 // The min old CSet region bound is based on the maximum desired 1861 // number of mixed GCs after a cycle. I.e., even if some old regions 1862 // look expensive, we should add them to the CSet anyway to make 1863 // sure we go through the available old regions in no more than the 1864 // maximum desired number of mixed GCs. 1865 // 1866 // The calculation is based on the number of marked regions we added 1867 // to the CSet chooser in the first place, not how many remain, so 1868 // that the result is the same during all mixed GCs that follow a cycle. 1869 1870 const size_t region_num = (size_t) _collectionSetChooser->length(); 1871 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); 1872 size_t result = region_num / gc_num; 1873 // emulate ceiling 1874 if (result * gc_num < region_num) { 1875 result += 1; 1876 } 1877 return (uint) result; 1878 } 1879 1880 uint G1CollectorPolicy::calc_max_old_cset_length() { 1881 // The max old CSet region bound is based on the threshold expressed 1882 // as a percentage of the heap size. I.e., it should bound the 1883 // number of old regions added to the CSet irrespective of how many 1884 // of them are available. 1885 1886 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1887 const size_t region_num = g1h->n_regions(); 1888 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; 1889 size_t result = region_num * perc / 100; 1890 // emulate ceiling 1891 if (100 * result < region_num * perc) { 1892 result += 1; 1893 } 1894 return (uint) result; 1895 } 1896 1897 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) { 1898 double young_start_time_sec = os::elapsedTime(); 1899 1900 YoungList* young_list = _g1->young_list(); 1901 finalize_incremental_cset_building(); 1902 1903 guarantee(target_pause_time_ms > 0.0, 1904 err_msg("target_pause_time_ms = %1.6lf should be positive", 1905 target_pause_time_ms)); 1906 guarantee(_collection_set == NULL, "Precondition"); 1907 1908 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards); 1909 double predicted_pause_time_ms = base_time_ms; 1910 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0); 1911 1912 ergo_verbose4(ErgoCSetConstruction | ErgoHigh, 1913 "start choosing CSet", 1914 ergo_format_size("_pending_cards") 1915 ergo_format_ms("predicted base time") 1916 ergo_format_ms("remaining time") 1917 ergo_format_ms("target pause time"), 1918 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms); 1919 1920 _last_gc_was_young = gcs_are_young() ? true : false; 1921 1922 if (_last_gc_was_young) { 1923 _trace_gen0_time_data.increment_young_collection_count(); 1924 } else { 1925 _trace_gen0_time_data.increment_mixed_collection_count(); 1926 } 1927 1928 // The young list is laid with the survivor regions from the previous 1929 // pause are appended to the RHS of the young list, i.e. 1930 // [Newly Young Regions ++ Survivors from last pause]. 1931 1932 uint survivor_region_length = young_list->survivor_length(); 1933 uint eden_region_length = young_list->length() - survivor_region_length; 1934 init_cset_region_lengths(eden_region_length, survivor_region_length); 1935 1936 HeapRegion* hr = young_list->first_survivor_region(); 1937 while (hr != NULL) { 1938 assert(hr->is_survivor(), "badly formed young list"); 1939 hr->set_young(); 1940 hr = hr->get_next_young_region(); 1941 } 1942 1943 // Clear the fields that point to the survivor list - they are all young now. 1944 young_list->clear_survivors(); 1945 1946 _collection_set = _inc_cset_head; 1947 _collection_set_bytes_used_before = _inc_cset_bytes_used_before; 1948 time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0); 1949 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms; 1950 1951 ergo_verbose3(ErgoCSetConstruction | ErgoHigh, 1952 "add young regions to CSet", 1953 ergo_format_region("eden") 1954 ergo_format_region("survivors") 1955 ergo_format_ms("predicted young region time"), 1956 eden_region_length, survivor_region_length, 1957 _inc_cset_predicted_elapsed_time_ms); 1958 1959 // The number of recorded young regions is the incremental 1960 // collection set's current size 1961 set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths); 1962 1963 double young_end_time_sec = os::elapsedTime(); 1964 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0); 1965 1966 // Set the start of the non-young choice time. 1967 double non_young_start_time_sec = young_end_time_sec; 1968 1969 if (!gcs_are_young()) { 1970 CollectionSetChooser* cset_chooser = _collectionSetChooser; 1971 cset_chooser->verify(); 1972 const uint min_old_cset_length = calc_min_old_cset_length(); 1973 const uint max_old_cset_length = calc_max_old_cset_length(); 1974 1975 uint expensive_region_num = 0; 1976 bool check_time_remaining = adaptive_young_list_length(); 1977 1978 HeapRegion* hr = cset_chooser->peek(); 1979 while (hr != NULL) { 1980 if (old_cset_region_length() >= max_old_cset_length) { 1981 // Added maximum number of old regions to the CSet. 1982 ergo_verbose2(ErgoCSetConstruction, 1983 "finish adding old regions to CSet", 1984 ergo_format_reason("old CSet region num reached max") 1985 ergo_format_region("old") 1986 ergo_format_region("max"), 1987 old_cset_region_length(), max_old_cset_length); 1988 break; 1989 } 1990 1991 1992 // Stop adding regions if the remaining reclaimable space is 1993 // not above G1HeapWastePercent. 1994 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes(); 1995 double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes); 1996 double threshold = (double) G1HeapWastePercent; 1997 if (reclaimable_perc <= threshold) { 1998 // We've added enough old regions that the amount of uncollected 1999 // reclaimable space is at or below the waste threshold. Stop 2000 // adding old regions to the CSet. 2001 ergo_verbose5(ErgoCSetConstruction, 2002 "finish adding old regions to CSet", 2003 ergo_format_reason("reclaimable percentage not over threshold") 2004 ergo_format_region("old") 2005 ergo_format_region("max") 2006 ergo_format_byte_perc("reclaimable") 2007 ergo_format_perc("threshold"), 2008 old_cset_region_length(), 2009 max_old_cset_length, 2010 reclaimable_bytes, 2011 reclaimable_perc, threshold); 2012 break; 2013 } 2014 2015 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young()); 2016 if (check_time_remaining) { 2017 if (predicted_time_ms > time_remaining_ms) { 2018 // Too expensive for the current CSet. 2019 2020 if (old_cset_region_length() >= min_old_cset_length) { 2021 // We have added the minimum number of old regions to the CSet, 2022 // we are done with this CSet. 2023 ergo_verbose4(ErgoCSetConstruction, 2024 "finish adding old regions to CSet", 2025 ergo_format_reason("predicted time is too high") 2026 ergo_format_ms("predicted time") 2027 ergo_format_ms("remaining time") 2028 ergo_format_region("old") 2029 ergo_format_region("min"), 2030 predicted_time_ms, time_remaining_ms, 2031 old_cset_region_length(), min_old_cset_length); 2032 break; 2033 } 2034 2035 // We'll add it anyway given that we haven't reached the 2036 // minimum number of old regions. 2037 expensive_region_num += 1; 2038 } 2039 } else { 2040 if (old_cset_region_length() >= min_old_cset_length) { 2041 // In the non-auto-tuning case, we'll finish adding regions 2042 // to the CSet if we reach the minimum. 2043 ergo_verbose2(ErgoCSetConstruction, 2044 "finish adding old regions to CSet", 2045 ergo_format_reason("old CSet region num reached min") 2046 ergo_format_region("old") 2047 ergo_format_region("min"), 2048 old_cset_region_length(), min_old_cset_length); 2049 break; 2050 } 2051 } 2052 2053 // We will add this region to the CSet. 2054 time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); 2055 predicted_pause_time_ms += predicted_time_ms; 2056 cset_chooser->remove_and_move_to_next(hr); 2057 _g1->old_set_remove(hr); 2058 add_old_region_to_cset(hr); 2059 2060 hr = cset_chooser->peek(); 2061 } 2062 if (hr == NULL) { 2063 ergo_verbose0(ErgoCSetConstruction, 2064 "finish adding old regions to CSet", 2065 ergo_format_reason("candidate old regions not available")); 2066 } 2067 2068 if (expensive_region_num > 0) { 2069 // We print the information once here at the end, predicated on 2070 // whether we added any apparently expensive regions or not, to 2071 // avoid generating output per region. 2072 ergo_verbose4(ErgoCSetConstruction, 2073 "added expensive regions to CSet", 2074 ergo_format_reason("old CSet region num not reached min") 2075 ergo_format_region("old") 2076 ergo_format_region("expensive") 2077 ergo_format_region("min") 2078 ergo_format_ms("remaining time"), 2079 old_cset_region_length(), 2080 expensive_region_num, 2081 min_old_cset_length, 2082 time_remaining_ms); 2083 } 2084 2085 cset_chooser->verify(); 2086 } 2087 2088 stop_incremental_cset_building(); 2089 2090 ergo_verbose5(ErgoCSetConstruction, 2091 "finish choosing CSet", 2092 ergo_format_region("eden") 2093 ergo_format_region("survivors") 2094 ergo_format_region("old") 2095 ergo_format_ms("predicted pause time") 2096 ergo_format_ms("target pause time"), 2097 eden_region_length, survivor_region_length, 2098 old_cset_region_length(), 2099 predicted_pause_time_ms, target_pause_time_ms); 2100 2101 double non_young_end_time_sec = os::elapsedTime(); 2102 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); 2103 evacuation_info.set_collectionset_regions(cset_region_length()); 2104 } 2105 2106 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) { 2107 if(TraceGen0Time) { 2108 _all_stop_world_times_ms.add(time_to_stop_the_world_ms); 2109 } 2110 } 2111 2112 void TraceGen0TimeData::record_yield_time(double yield_time_ms) { 2113 if(TraceGen0Time) { 2114 _all_yield_times_ms.add(yield_time_ms); 2115 } 2116 } 2117 2118 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) { 2119 if(TraceGen0Time) { 2120 _total.add(pause_time_ms); 2121 _other.add(pause_time_ms - phase_times->accounted_time_ms()); 2122 _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms()); 2123 _parallel.add(phase_times->cur_collection_par_time_ms()); 2124 _ext_root_scan.add(phase_times->average_last_ext_root_scan_time()); 2125 _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms()); 2126 _update_rs.add(phase_times->average_last_update_rs_time()); 2127 _scan_rs.add(phase_times->average_last_scan_rs_time()); 2128 _obj_copy.add(phase_times->average_last_obj_copy_time()); 2129 _termination.add(phase_times->average_last_termination_time()); 2130 2131 double parallel_known_time = phase_times->average_last_ext_root_scan_time() + 2132 phase_times->average_last_satb_filtering_times_ms() + 2133 phase_times->average_last_update_rs_time() + 2134 phase_times->average_last_scan_rs_time() + 2135 phase_times->average_last_obj_copy_time() + 2136 + phase_times->average_last_termination_time(); 2137 2138 double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time; 2139 _parallel_other.add(parallel_other_time); 2140 _clear_ct.add(phase_times->cur_clear_ct_time_ms()); 2141 } 2142 } 2143 2144 void TraceGen0TimeData::increment_young_collection_count() { 2145 if(TraceGen0Time) { 2146 ++_young_pause_num; 2147 } 2148 } 2149 2150 void TraceGen0TimeData::increment_mixed_collection_count() { 2151 if(TraceGen0Time) { 2152 ++_mixed_pause_num; 2153 } 2154 } 2155 2156 void TraceGen0TimeData::print_summary(const char* str, 2157 const NumberSeq* seq) const { 2158 double sum = seq->sum(); 2159 gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)", 2160 str, sum / 1000.0, seq->avg()); 2161 } 2162 2163 void TraceGen0TimeData::print_summary_sd(const char* str, 2164 const NumberSeq* seq) const { 2165 print_summary(str, seq); 2166 gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)", 2167 "(num", seq->num(), seq->sd(), seq->maximum()); 2168 } 2169 2170 void TraceGen0TimeData::print() const { 2171 if (!TraceGen0Time) { 2172 return; 2173 } 2174 2175 gclog_or_tty->print_cr("ALL PAUSES"); 2176 print_summary_sd(" Total", &_total); 2177 gclog_or_tty->print_cr(""); 2178 gclog_or_tty->print_cr(""); 2179 gclog_or_tty->print_cr(" Young GC Pauses: %8d", _young_pause_num); 2180 gclog_or_tty->print_cr(" Mixed GC Pauses: %8d", _mixed_pause_num); 2181 gclog_or_tty->print_cr(""); 2182 2183 gclog_or_tty->print_cr("EVACUATION PAUSES"); 2184 2185 if (_young_pause_num == 0 && _mixed_pause_num == 0) { 2186 gclog_or_tty->print_cr("none"); 2187 } else { 2188 print_summary_sd(" Evacuation Pauses", &_total); 2189 print_summary(" Root Region Scan Wait", &_root_region_scan_wait); 2190 print_summary(" Parallel Time", &_parallel); 2191 print_summary(" Ext Root Scanning", &_ext_root_scan); 2192 print_summary(" SATB Filtering", &_satb_filtering); 2193 print_summary(" Update RS", &_update_rs); 2194 print_summary(" Scan RS", &_scan_rs); 2195 print_summary(" Object Copy", &_obj_copy); 2196 print_summary(" Termination", &_termination); 2197 print_summary(" Parallel Other", &_parallel_other); 2198 print_summary(" Clear CT", &_clear_ct); 2199 print_summary(" Other", &_other); 2200 } 2201 gclog_or_tty->print_cr(""); 2202 2203 gclog_or_tty->print_cr("MISC"); 2204 print_summary_sd(" Stop World", &_all_stop_world_times_ms); 2205 print_summary_sd(" Yields", &_all_yield_times_ms); 2206 } 2207 2208 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) { 2209 if (TraceGen1Time) { 2210 _all_full_gc_times.add(full_gc_time_ms); 2211 } 2212 } 2213 2214 void TraceGen1TimeData::print() const { 2215 if (!TraceGen1Time) { 2216 return; 2217 } 2218 2219 if (_all_full_gc_times.num() > 0) { 2220 gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s", 2221 _all_full_gc_times.num(), 2222 _all_full_gc_times.sum() / 1000.0); 2223 gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg()); 2224 gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]", 2225 _all_full_gc_times.sd(), 2226 _all_full_gc_times.maximum()); 2227 } 2228 }