1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/concurrentMark.hpp"
  28 #include "gc/g1/concurrentMarkThread.inline.hpp"
  29 #include "gc/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc/g1/g1CollectorPolicy.hpp"
  31 #include "gc/g1/g1GCPhaseTimes.hpp"
  32 #include "gc/g1/heapRegion.inline.hpp"
  33 #include "gc/g1/heapRegionRemSet.hpp"
  34 #include "gc/shared/gcPolicyCounters.hpp"
  35 #include "logging/log.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   _predictor(G1ConfidencePercent / 100.0),
  83   _parallel_gc_threads(ParallelGCThreads),
  84 
  85   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  86   _stop_world_start(0.0),
  87 
  88   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  89   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  90 
  91   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  92   _prev_collection_pause_end_ms(0.0),
  93   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  94   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _non_young_other_cost_per_region_ms_seq(
 105                                          new TruncatedSeq(TruncatedSeqLength)),
 106 
 107   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 108   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 109 
 110   _pause_time_target_ms((double) MaxGCPauseMillis),
 111 
 112   _recent_prev_end_times_for_all_gcs_sec(
 113                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 114 
 115   _recent_avg_pause_time_ratio(0.0),
 116   _rs_lengths_prediction(0),
 117   _max_survivor_regions(0),
 118 
 119   _eden_used_bytes_before_gc(0),
 120   _survivor_used_bytes_before_gc(0),
 121   _old_used_bytes_before_gc(0),
 122   _heap_used_bytes_before_gc(0),
 123   _metaspace_used_bytes_before_gc(0),
 124   _eden_capacity_bytes_before_gc(0),
 125   _heap_capacity_bytes_before_gc(0),
 126 
 127   _eden_cset_region_length(0),
 128   _survivor_cset_region_length(0),
 129   _old_cset_region_length(0),
 130 
 131   _collection_set(NULL),
 132   _collection_set_bytes_used_before(0),
 133 
 134   // Incremental CSet attributes
 135   _inc_cset_build_state(Inactive),
 136   _inc_cset_head(NULL),
 137   _inc_cset_tail(NULL),
 138   _inc_cset_bytes_used_before(0),
 139   _inc_cset_max_finger(NULL),
 140   _inc_cset_recorded_rs_lengths(0),
 141   _inc_cset_recorded_rs_lengths_diffs(0),
 142   _inc_cset_predicted_elapsed_time_ms(0.0),
 143   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 144 
 145   // add here any more surv rate groups
 146   _recorded_survivor_regions(0),
 147   _recorded_survivor_head(NULL),
 148   _recorded_survivor_tail(NULL),
 149   _survivors_age_table(true),
 150 
 151   _gc_overhead_perc(0.0) {
 152 
 153   // SurvRateGroups below must be initialized after the predictor because they
 154   // indirectly use it through this object passed to their constructor.
 155   _short_lived_surv_rate_group =
 156     new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
 157   _survivor_surv_rate_group =
 158     new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
 159 
 160   // Set up the region size and associated fields. Given that the
 161   // policy is created before the heap, we have to set this up here,
 162   // so it's done as soon as possible.
 163 
 164   // It would have been natural to pass initial_heap_byte_size() and
 165   // max_heap_byte_size() to setup_heap_region_size() but those have
 166   // not been set up at this point since they should be aligned with
 167   // the region size. So, there is a circular dependency here. We base
 168   // the region size on the heap size, but the heap size should be
 169   // aligned with the region size. To get around this we use the
 170   // unaligned values for the heap.
 171   HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
 172   HeapRegionRemSet::setup_remset_size();
 173 
 174   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 175   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 176 
 177   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 178 
 179   int index = MIN2(_parallel_gc_threads - 1, 7);
 180 
 181   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 182   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 183   _cost_scan_hcc_seq->add(0.0);
 184   _young_cards_per_entry_ratio_seq->add(
 185                                   young_cards_per_entry_ratio_defaults[index]);
 186   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 187   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 188   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 189   _young_other_cost_per_region_ms_seq->add(
 190                                young_other_cost_per_region_ms_defaults[index]);
 191   _non_young_other_cost_per_region_ms_seq->add(
 192                            non_young_other_cost_per_region_ms_defaults[index]);
 193 
 194   // Below, we might need to calculate the pause time target based on
 195   // the pause interval. When we do so we are going to give G1 maximum
 196   // flexibility and allow it to do pauses when it needs to. So, we'll
 197   // arrange that the pause interval to be pause time target + 1 to
 198   // ensure that a) the pause time target is maximized with respect to
 199   // the pause interval and b) we maintain the invariant that pause
 200   // time target < pause interval. If the user does not want this
 201   // maximum flexibility, they will have to set the pause interval
 202   // explicitly.
 203 
 204   // First make sure that, if either parameter is set, its value is
 205   // reasonable.
 206   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 207     if (MaxGCPauseMillis < 1) {
 208       vm_exit_during_initialization("MaxGCPauseMillis should be "
 209                                     "greater than 0");
 210     }
 211   }
 212   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 213     if (GCPauseIntervalMillis < 1) {
 214       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 215                                     "greater than 0");
 216     }
 217   }
 218 
 219   // Then, if the pause time target parameter was not set, set it to
 220   // the default value.
 221   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 222     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 223       // The default pause time target in G1 is 200ms
 224       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 225     } else {
 226       // We do not allow the pause interval to be set without the
 227       // pause time target
 228       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 229                                     "without setting MaxGCPauseMillis");
 230     }
 231   }
 232 
 233   // Then, if the interval parameter was not set, set it according to
 234   // the pause time target (this will also deal with the case when the
 235   // pause time target is the default value).
 236   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 237     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 238   }
 239 
 240   // Finally, make sure that the two parameters are consistent.
 241   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 242     char buffer[256];
 243     jio_snprintf(buffer, 256,
 244                  "MaxGCPauseMillis (%u) should be less than "
 245                  "GCPauseIntervalMillis (%u)",
 246                  MaxGCPauseMillis, GCPauseIntervalMillis);
 247     vm_exit_during_initialization(buffer);
 248   }
 249 
 250   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 251   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 252   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 253 
 254   // start conservatively (around 50ms is about right)
 255   _concurrent_mark_remark_times_ms->add(0.05);
 256   _concurrent_mark_cleanup_times_ms->add(0.20);
 257   _tenuring_threshold = MaxTenuringThreshold;
 258 
 259   assert(GCTimeRatio > 0,
 260          "we should have set it to a default value set_g1_gc_flags() "
 261          "if a user set it to 0");
 262   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 263 
 264   uintx reserve_perc = G1ReservePercent;
 265   // Put an artificial ceiling on this so that it's not set to a silly value.
 266   if (reserve_perc > 50) {
 267     reserve_perc = 50;
 268     warning("G1ReservePercent is set to a value that is too large, "
 269             "it's been updated to " UINTX_FORMAT, reserve_perc);
 270   }
 271   _reserve_factor = (double) reserve_perc / 100.0;
 272   // This will be set when the heap is expanded
 273   // for the first time during initialization.
 274   _reserve_regions = 0;
 275 
 276   _collectionSetChooser = new CollectionSetChooser();
 277 }
 278 
 279 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
 280   return _predictor.get_new_prediction(seq);
 281 }
 282 
 283 void G1CollectorPolicy::initialize_alignments() {
 284   _space_alignment = HeapRegion::GrainBytes;
 285   size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
 286   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
 287   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 288 }
 289 
 290 void G1CollectorPolicy::initialize_flags() {
 291   if (G1HeapRegionSize != HeapRegion::GrainBytes) {
 292     FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
 293   }
 294 
 295   if (SurvivorRatio < 1) {
 296     vm_exit_during_initialization("Invalid survivor ratio specified");
 297   }
 298   CollectorPolicy::initialize_flags();
 299   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 300 }
 301 
 302 void G1CollectorPolicy::post_heap_initialize() {
 303   uintx max_regions = G1CollectedHeap::heap()->max_regions();
 304   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
 305   if (max_young_size != MaxNewSize) {
 306     FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
 307   }
 308 }
 309 
 310 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
 311 
 312 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
 313         _min_desired_young_length(0), _max_desired_young_length(0) {
 314   if (FLAG_IS_CMDLINE(NewRatio)) {
 315     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 316       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 317     } else {
 318       _sizer_kind = SizerNewRatio;
 319       _adaptive_size = false;
 320       return;
 321     }
 322   }
 323 
 324   if (NewSize > MaxNewSize) {
 325     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 326       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 327               "A new max generation size of " SIZE_FORMAT "k will be used.",
 328               NewSize/K, MaxNewSize/K, NewSize/K);
 329     }
 330     MaxNewSize = NewSize;
 331   }
 332 
 333   if (FLAG_IS_CMDLINE(NewSize)) {
 334     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 335                                      1U);
 336     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 337       _max_desired_young_length =
 338                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 339                                   1U);
 340       _sizer_kind = SizerMaxAndNewSize;
 341       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 342     } else {
 343       _sizer_kind = SizerNewSizeOnly;
 344     }
 345   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 346     _max_desired_young_length =
 347                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 348                                   1U);
 349     _sizer_kind = SizerMaxNewSizeOnly;
 350   }
 351 }
 352 
 353 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 354   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 355   return MAX2(1U, default_value);
 356 }
 357 
 358 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 359   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 360   return MAX2(1U, default_value);
 361 }
 362 
 363 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
 364   assert(number_of_heap_regions > 0, "Heap must be initialized");
 365 
 366   switch (_sizer_kind) {
 367     case SizerDefaults:
 368       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 369       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 370       break;
 371     case SizerNewSizeOnly:
 372       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 373       *max_young_length = MAX2(*min_young_length, *max_young_length);
 374       break;
 375     case SizerMaxNewSizeOnly:
 376       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 377       *min_young_length = MIN2(*min_young_length, *max_young_length);
 378       break;
 379     case SizerMaxAndNewSize:
 380       // Do nothing. Values set on the command line, don't update them at runtime.
 381       break;
 382     case SizerNewRatio:
 383       *min_young_length = number_of_heap_regions / (NewRatio + 1);
 384       *max_young_length = *min_young_length;
 385       break;
 386     default:
 387       ShouldNotReachHere();
 388   }
 389 
 390   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
 391 }
 392 
 393 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
 394   // We need to pass the desired values because recalculation may not update these
 395   // values in some cases.
 396   uint temp = _min_desired_young_length;
 397   uint result = _max_desired_young_length;
 398   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
 399   return result;
 400 }
 401 
 402 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 403   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
 404           &_max_desired_young_length);
 405 }
 406 
 407 void G1CollectorPolicy::init() {
 408   // Set aside an initial future to_space.
 409   _g1 = G1CollectedHeap::heap();
 410 
 411   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 412 
 413   initialize_gc_policy_counters();
 414 
 415   if (adaptive_young_list_length()) {
 416     _young_list_fixed_length = 0;
 417   } else {
 418     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 419   }
 420   _free_regions_at_end_of_collection = _g1->num_free_regions();
 421 
 422   update_young_list_max_and_target_length();
 423   // We may immediately start allocating regions and placing them on the
 424   // collection set list. Initialize the per-collection set info
 425   start_incremental_cset_building();
 426 }
 427 
 428 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
 429   phase_times()->note_gc_start(num_active_workers);
 430 }
 431 
 432 // Create the jstat counters for the policy.
 433 void G1CollectorPolicy::initialize_gc_policy_counters() {
 434   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 435 }
 436 
 437 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 438                                          double base_time_ms,
 439                                          uint base_free_regions,
 440                                          double target_pause_time_ms) const {
 441   if (young_length >= base_free_regions) {
 442     // end condition 1: not enough space for the young regions
 443     return false;
 444   }
 445 
 446   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 447   size_t bytes_to_copy =
 448                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 449   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 450   double young_other_time_ms = predict_young_other_time_ms(young_length);
 451   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 452   if (pause_time_ms > target_pause_time_ms) {
 453     // end condition 2: prediction is over the target pause time
 454     return false;
 455   }
 456 
 457   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 458 
 459   // When copying, we will likely need more bytes free than is live in the region.
 460   // Add some safety margin to factor in the confidence of our guess, and the
 461   // natural expected waste.
 462   // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 463   // of the calculation: the lower the confidence, the more headroom.
 464   // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 465   // copying due to anticipated waste in the PLABs.
 466   double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 467   size_t expected_bytes_to_copy = safety_factor * bytes_to_copy;
 468 
 469   if (expected_bytes_to_copy > free_bytes) {
 470     // end condition 3: out-of-space
 471     return false;
 472   }
 473 
 474   // success!
 475   return true;
 476 }
 477 
 478 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 479   // re-calculate the necessary reserve
 480   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 481   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 482   // smaller than 1.0) we'll get 1.
 483   _reserve_regions = (uint) ceil(reserve_regions_d);
 484 
 485   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 486 }
 487 
 488 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 489                                                        uint base_min_length) const {
 490   uint desired_min_length = 0;
 491   if (adaptive_young_list_length()) {
 492     if (_alloc_rate_ms_seq->num() > 3) {
 493       double now_sec = os::elapsedTime();
 494       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 495       double alloc_rate_ms = predict_alloc_rate_ms();
 496       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 497     } else {
 498       // otherwise we don't have enough info to make the prediction
 499     }
 500   }
 501   desired_min_length += base_min_length;
 502   // make sure we don't go below any user-defined minimum bound
 503   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 504 }
 505 
 506 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
 507   // Here, we might want to also take into account any additional
 508   // constraints (i.e., user-defined minimum bound). Currently, we
 509   // effectively don't set this bound.
 510   return _young_gen_sizer->max_desired_young_length();
 511 }
 512 
 513 void G1CollectorPolicy::update_young_list_max_and_target_length() {
 514   update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq));
 515 }
 516 
 517 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 518   update_young_list_target_length(rs_lengths);
 519   update_max_gc_locker_expansion();
 520 }
 521 
 522 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 523   _young_list_target_length = bounded_young_list_target_length(rs_lengths);
 524 }
 525 
 526 void G1CollectorPolicy::update_young_list_target_length() {
 527   update_young_list_target_length(get_new_prediction(_rs_lengths_seq));
 528 }
 529 
 530 uint G1CollectorPolicy::bounded_young_list_target_length(size_t rs_lengths) const {
 531   // Calculate the absolute and desired min bounds.
 532 
 533   // This is how many young regions we already have (currently: the survivors).
 534   uint base_min_length = recorded_survivor_regions();
 535   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 536   // This is the absolute minimum young length. Ensure that we
 537   // will at least have one eden region available for allocation.
 538   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 539   // If we shrank the young list target it should not shrink below the current size.
 540   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 541   // Calculate the absolute and desired max bounds.
 542 
 543   // We will try our best not to "eat" into the reserve.
 544   uint absolute_max_length = 0;
 545   if (_free_regions_at_end_of_collection > _reserve_regions) {
 546     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 547   }
 548   uint desired_max_length = calculate_young_list_desired_max_length();
 549   if (desired_max_length > absolute_max_length) {
 550     desired_max_length = absolute_max_length;
 551   }
 552 
 553   uint young_list_target_length = 0;
 554   if (adaptive_young_list_length()) {
 555     if (collector_state()->gcs_are_young()) {
 556       young_list_target_length =
 557                         calculate_young_list_target_length(rs_lengths,
 558                                                            base_min_length,
 559                                                            desired_min_length,
 560                                                            desired_max_length);
 561     } else {
 562       // Don't calculate anything and let the code below bound it to
 563       // the desired_min_length, i.e., do the next GC as soon as
 564       // possible to maximize how many old regions we can add to it.
 565     }
 566   } else {
 567     // The user asked for a fixed young gen so we'll fix the young gen
 568     // whether the next GC is young or mixed.
 569     young_list_target_length = _young_list_fixed_length;
 570   }
 571 
 572   // Make sure we don't go over the desired max length, nor under the
 573   // desired min length. In case they clash, desired_min_length wins
 574   // which is why that test is second.
 575   if (young_list_target_length > desired_max_length) {
 576     young_list_target_length = desired_max_length;
 577   }
 578   if (young_list_target_length < desired_min_length) {
 579     young_list_target_length = desired_min_length;
 580   }
 581 
 582   assert(young_list_target_length > recorded_survivor_regions(),
 583          "we should be able to allocate at least one eden region");
 584   assert(young_list_target_length >= absolute_min_length, "post-condition");
 585 
 586   return young_list_target_length;
 587 }
 588 
 589 uint
 590 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 591                                                      uint base_min_length,
 592                                                      uint desired_min_length,
 593                                                      uint desired_max_length) const {
 594   assert(adaptive_young_list_length(), "pre-condition");
 595   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 596 
 597   // In case some edge-condition makes the desired max length too small...
 598   if (desired_max_length <= desired_min_length) {
 599     return desired_min_length;
 600   }
 601 
 602   // We'll adjust min_young_length and max_young_length not to include
 603   // the already allocated young regions (i.e., so they reflect the
 604   // min and max eden regions we'll allocate). The base_min_length
 605   // will be reflected in the predictions by the
 606   // survivor_regions_evac_time prediction.
 607   assert(desired_min_length > base_min_length, "invariant");
 608   uint min_young_length = desired_min_length - base_min_length;
 609   assert(desired_max_length > base_min_length, "invariant");
 610   uint max_young_length = desired_max_length - base_min_length;
 611 
 612   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 613   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 614   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 615   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 616   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 617   double base_time_ms =
 618     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 619     survivor_regions_evac_time;
 620   uint available_free_regions = _free_regions_at_end_of_collection;
 621   uint base_free_regions = 0;
 622   if (available_free_regions > _reserve_regions) {
 623     base_free_regions = available_free_regions - _reserve_regions;
 624   }
 625 
 626   // Here, we will make sure that the shortest young length that
 627   // makes sense fits within the target pause time.
 628 
 629   if (predict_will_fit(min_young_length, base_time_ms,
 630                        base_free_regions, target_pause_time_ms)) {
 631     // The shortest young length will fit into the target pause time;
 632     // we'll now check whether the absolute maximum number of young
 633     // regions will fit in the target pause time. If not, we'll do
 634     // a binary search between min_young_length and max_young_length.
 635     if (predict_will_fit(max_young_length, base_time_ms,
 636                          base_free_regions, target_pause_time_ms)) {
 637       // The maximum young length will fit into the target pause time.
 638       // We are done so set min young length to the maximum length (as
 639       // the result is assumed to be returned in min_young_length).
 640       min_young_length = max_young_length;
 641     } else {
 642       // The maximum possible number of young regions will not fit within
 643       // the target pause time so we'll search for the optimal
 644       // length. The loop invariants are:
 645       //
 646       // min_young_length < max_young_length
 647       // min_young_length is known to fit into the target pause time
 648       // max_young_length is known not to fit into the target pause time
 649       //
 650       // Going into the loop we know the above hold as we've just
 651       // checked them. Every time around the loop we check whether
 652       // the middle value between min_young_length and
 653       // max_young_length fits into the target pause time. If it
 654       // does, it becomes the new min. If it doesn't, it becomes
 655       // the new max. This way we maintain the loop invariants.
 656 
 657       assert(min_young_length < max_young_length, "invariant");
 658       uint diff = (max_young_length - min_young_length) / 2;
 659       while (diff > 0) {
 660         uint young_length = min_young_length + diff;
 661         if (predict_will_fit(young_length, base_time_ms,
 662                              base_free_regions, target_pause_time_ms)) {
 663           min_young_length = young_length;
 664         } else {
 665           max_young_length = young_length;
 666         }
 667         assert(min_young_length <  max_young_length, "invariant");
 668         diff = (max_young_length - min_young_length) / 2;
 669       }
 670       // The results is min_young_length which, according to the
 671       // loop invariants, should fit within the target pause time.
 672 
 673       // These are the post-conditions of the binary search above:
 674       assert(min_young_length < max_young_length,
 675              "otherwise we should have discovered that max_young_length "
 676              "fits into the pause target and not done the binary search");
 677       assert(predict_will_fit(min_young_length, base_time_ms,
 678                               base_free_regions, target_pause_time_ms),
 679              "min_young_length, the result of the binary search, should "
 680              "fit into the pause target");
 681       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 682                                base_free_regions, target_pause_time_ms),
 683              "min_young_length, the result of the binary search, should be "
 684              "optimal, so no larger length should fit into the pause target");
 685     }
 686   } else {
 687     // Even the minimum length doesn't fit into the pause time
 688     // target, return it as the result nevertheless.
 689   }
 690   return base_min_length + min_young_length;
 691 }
 692 
 693 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
 694   double survivor_regions_evac_time = 0.0;
 695   for (HeapRegion * r = _recorded_survivor_head;
 696        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 697        r = r->get_next_young_region()) {
 698     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 699   }
 700   return survivor_regions_evac_time;
 701 }
 702 
 703 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 704   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 705 
 706   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 707   if (rs_lengths > _rs_lengths_prediction) {
 708     // add 10% to avoid having to recalculate often
 709     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 710     update_rs_lengths_prediction(rs_lengths_prediction);
 711 
 712     update_young_list_max_and_target_length(rs_lengths_prediction);
 713   }
 714 }
 715 
 716 void G1CollectorPolicy::update_rs_lengths_prediction() {
 717   update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
 718 }
 719 
 720 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
 721   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 722     _rs_lengths_prediction = prediction;
 723   }
 724 }
 725 
 726 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 727                                                bool is_tlab,
 728                                                bool* gc_overhead_limit_was_exceeded) {
 729   guarantee(false, "Not using this policy feature yet.");
 730   return NULL;
 731 }
 732 
 733 // This method controls how a collector handles one or more
 734 // of its generations being fully allocated.
 735 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 736                                                        bool is_tlab) {
 737   guarantee(false, "Not using this policy feature yet.");
 738   return NULL;
 739 }
 740 
 741 
 742 #ifndef PRODUCT
 743 bool G1CollectorPolicy::verify_young_ages() {
 744   HeapRegion* head = _g1->young_list()->first_region();
 745   return
 746     verify_young_ages(head, _short_lived_surv_rate_group);
 747   // also call verify_young_ages on any additional surv rate groups
 748 }
 749 
 750 bool
 751 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 752                                      SurvRateGroup *surv_rate_group) {
 753   guarantee( surv_rate_group != NULL, "pre-condition" );
 754 
 755   const char* name = surv_rate_group->name();
 756   bool ret = true;
 757   int prev_age = -1;
 758 
 759   for (HeapRegion* curr = head;
 760        curr != NULL;
 761        curr = curr->get_next_young_region()) {
 762     SurvRateGroup* group = curr->surv_rate_group();
 763     if (group == NULL && !curr->is_survivor()) {
 764       log_info(gc, verify)("## %s: encountered NULL surv_rate_group", name);
 765       ret = false;
 766     }
 767 
 768     if (surv_rate_group == group) {
 769       int age = curr->age_in_surv_rate_group();
 770 
 771       if (age < 0) {
 772         log_info(gc, verify)("## %s: encountered negative age", name);
 773         ret = false;
 774       }
 775 
 776       if (age <= prev_age) {
 777         log_info(gc, verify)("## %s: region ages are not strictly increasing (%d, %d)", name, age, prev_age);
 778         ret = false;
 779       }
 780       prev_age = age;
 781     }
 782   }
 783 
 784   return ret;
 785 }
 786 #endif // PRODUCT
 787 
 788 void G1CollectorPolicy::record_full_collection_start() {
 789   _full_collection_start_sec = os::elapsedTime();
 790   record_heap_size_info_at_start(true /* full */);
 791   // Release the future to-space so that it is available for compaction into.
 792   collector_state()->set_full_collection(true);
 793 }
 794 
 795 void G1CollectorPolicy::record_full_collection_end() {
 796   // Consider this like a collection pause for the purposes of allocation
 797   // since last pause.
 798   double end_sec = os::elapsedTime();
 799   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 800   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 801 
 802   _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
 803 
 804   update_recent_gc_times(end_sec, full_gc_time_ms);
 805 
 806   collector_state()->set_full_collection(false);
 807 
 808   // "Nuke" the heuristics that control the young/mixed GC
 809   // transitions and make sure we start with young GCs after the Full GC.
 810   collector_state()->set_gcs_are_young(true);
 811   collector_state()->set_last_young_gc(false);
 812   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 813   collector_state()->set_during_initial_mark_pause(false);
 814   collector_state()->set_in_marking_window(false);
 815   collector_state()->set_in_marking_window_im(false);
 816 
 817   _short_lived_surv_rate_group->start_adding_regions();
 818   // also call this on any additional surv rate groups
 819 
 820   record_survivor_regions(0, NULL, NULL);
 821 
 822   _free_regions_at_end_of_collection = _g1->num_free_regions();
 823   // Reset survivors SurvRateGroup.
 824   _survivor_surv_rate_group->reset();
 825   update_young_list_max_and_target_length();
 826   update_rs_lengths_prediction();
 827   _collectionSetChooser->clear();
 828 }
 829 
 830 void G1CollectorPolicy::record_stop_world_start() {
 831   _stop_world_start = os::elapsedTime();
 832 }
 833 
 834 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
 835   // We only need to do this here as the policy will only be applied
 836   // to the GC we're about to start. so, no point is calculating this
 837   // every time we calculate / recalculate the target young length.
 838   update_survivors_policy();
 839 
 840   assert(_g1->used() == _g1->recalculate_used(),
 841          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 842          _g1->used(), _g1->recalculate_used());
 843 
 844   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 845   _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
 846   _stop_world_start = 0.0;
 847 
 848   record_heap_size_info_at_start(false /* full */);
 849 
 850   phase_times()->record_cur_collection_start_sec(start_time_sec);
 851   _pending_cards = _g1->pending_card_num();
 852 
 853   _collection_set_bytes_used_before = 0;
 854   _bytes_copied_during_gc = 0;
 855 
 856   collector_state()->set_last_gc_was_young(false);
 857 
 858   // do that for any other surv rate groups
 859   _short_lived_surv_rate_group->stop_adding_regions();
 860   _survivors_age_table.clear();
 861 
 862   assert( verify_young_ages(), "region age verification" );
 863 }
 864 
 865 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 866                                                    mark_init_elapsed_time_ms) {
 867   collector_state()->set_during_marking(true);
 868   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 869   collector_state()->set_during_initial_mark_pause(false);
 870   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 871 }
 872 
 873 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 874   _mark_remark_start_sec = os::elapsedTime();
 875   collector_state()->set_during_marking(false);
 876 }
 877 
 878 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 879   double end_time_sec = os::elapsedTime();
 880   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 881   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 882   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 883   _prev_collection_pause_end_ms += elapsed_time_ms;
 884 
 885   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec);
 886 }
 887 
 888 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 889   _mark_cleanup_start_sec = os::elapsedTime();
 890 }
 891 
 892 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 893   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 894                                                               "skip last young-only gc");
 895   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 896   collector_state()->set_in_marking_window(false);
 897 }
 898 
 899 void G1CollectorPolicy::record_concurrent_pause() {
 900   if (_stop_world_start > 0.0) {
 901     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 902     _trace_young_gen_time_data.record_yield_time(yield_ms);
 903   }
 904 }
 905 
 906 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 907   return phase_times()->average_time_ms(phase);
 908 }
 909 
 910 double G1CollectorPolicy::young_other_time_ms() const {
 911   return phase_times()->young_cset_choice_time_ms() +
 912          phase_times()->young_free_cset_time_ms();
 913 }
 914 
 915 double G1CollectorPolicy::non_young_other_time_ms() const {
 916   return phase_times()->non_young_cset_choice_time_ms() +
 917          phase_times()->non_young_free_cset_time_ms();
 918 
 919 }
 920 
 921 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
 922   return pause_time_ms -
 923          average_time_ms(G1GCPhaseTimes::UpdateRS) -
 924          average_time_ms(G1GCPhaseTimes::ScanRS) -
 925          average_time_ms(G1GCPhaseTimes::ObjCopy) -
 926          average_time_ms(G1GCPhaseTimes::Termination);
 927 }
 928 
 929 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
 930   return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
 931 }
 932 
 933 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
 934   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 935 }
 936 
 937 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 938   if (about_to_start_mixed_phase()) {
 939     return false;
 940   }
 941 
 942   size_t marking_initiating_used_threshold =
 943     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
 944   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 945   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 946 
 947   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
 948     if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
 949       log_debug(gc, ergo)("Request concurrent cycle initiation (occupancy higher than threshold)"
 950                           "occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (" UINTX_FORMAT "%%) source: %s",
 951                           cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, InitiatingHeapOccupancyPercent, source);
 952       return true;
 953     } else {
 954       log_debug(gc, ergo)("Do not request concurrent cycle initiation (still doing mixed collections)"
 955                           "occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (" UINTX_FORMAT "%%) source: %s",
 956                           cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, InitiatingHeapOccupancyPercent, source);    }
 957   }
 958 
 959   return false;
 960 }
 961 
 962 // Anything below that is considered to be zero
 963 #define MIN_TIMER_GRANULARITY 0.0000001
 964 
 965 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
 966   double end_time_sec = os::elapsedTime();
 967   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
 968          "otherwise, the subtraction below does not make sense");
 969   size_t rs_size =
 970             _cur_collection_pause_used_regions_at_start - cset_region_length();
 971   size_t cur_used_bytes = _g1->used();
 972   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 973   bool last_pause_included_initial_mark = false;
 974   bool update_stats = !_g1->evacuation_failed();
 975 
 976   NOT_PRODUCT(_short_lived_surv_rate_group->print());
 977 
 978   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
 979   if (last_pause_included_initial_mark) {
 980     record_concurrent_mark_init_end(0.0);
 981   } else {
 982     maybe_start_marking();
 983   }
 984 
 985   _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0, end_time_sec);
 986 
 987   if (update_stats) {
 988     _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
 989     // this is where we update the allocation rate of the application
 990     double app_time_ms =
 991       (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
 992     if (app_time_ms < MIN_TIMER_GRANULARITY) {
 993       // This usually happens due to the timer not having the required
 994       // granularity. Some Linuxes are the usual culprits.
 995       // We'll just set it to something (arbitrarily) small.
 996       app_time_ms = 1.0;
 997     }
 998     // We maintain the invariant that all objects allocated by mutator
 999     // threads will be allocated out of eden regions. So, we can use
1000     // the eden region number allocated since the previous GC to
1001     // calculate the application's allocate rate. The only exception
1002     // to that is humongous objects that are allocated separately. But
1003     // given that humongous object allocations do not really affect
1004     // either the pause's duration nor when the next pause will take
1005     // place we can safely ignore them here.
1006     uint regions_allocated = eden_cset_region_length();
1007     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1008     _alloc_rate_ms_seq->add(alloc_rate_ms);
1009 
1010     double interval_ms =
1011       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1012     update_recent_gc_times(end_time_sec, pause_time_ms);
1013     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1014     if (recent_avg_pause_time_ratio() < 0.0 ||
1015         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1016       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1017       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1018       if (_recent_avg_pause_time_ratio < 0.0) {
1019         _recent_avg_pause_time_ratio = 0.0;
1020       } else {
1021         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1022         _recent_avg_pause_time_ratio = 1.0;
1023       }
1024     }
1025   }
1026 
1027   bool new_in_marking_window = collector_state()->in_marking_window();
1028   bool new_in_marking_window_im = false;
1029   if (last_pause_included_initial_mark) {
1030     new_in_marking_window = true;
1031     new_in_marking_window_im = true;
1032   }
1033 
1034   if (collector_state()->last_young_gc()) {
1035     // This is supposed to to be the "last young GC" before we start
1036     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1037     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1038 
1039     if (next_gc_should_be_mixed("start mixed GCs",
1040                                 "do not start mixed GCs")) {
1041       collector_state()->set_gcs_are_young(false);
1042     }
1043 
1044     collector_state()->set_last_young_gc(false);
1045   }
1046 
1047   if (!collector_state()->last_gc_was_young()) {
1048     // This is a mixed GC. Here we decide whether to continue doing
1049     // mixed GCs or not.
1050 
1051     if (!next_gc_should_be_mixed("continue mixed GCs",
1052                                  "do not continue mixed GCs")) {
1053       collector_state()->set_gcs_are_young(true);
1054 
1055       maybe_start_marking();
1056     }
1057   }
1058 
1059   _short_lived_surv_rate_group->start_adding_regions();
1060   // Do that for any other surv rate groups
1061 
1062   if (update_stats) {
1063     double cost_per_card_ms = 0.0;
1064     double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1065     if (_pending_cards > 0) {
1066       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1067       _cost_per_card_ms_seq->add(cost_per_card_ms);
1068     }
1069     _cost_scan_hcc_seq->add(cost_scan_hcc);
1070 
1071     double cost_per_entry_ms = 0.0;
1072     if (cards_scanned > 10) {
1073       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1074       if (collector_state()->last_gc_was_young()) {
1075         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1076       } else {
1077         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1078       }
1079     }
1080 
1081     if (_max_rs_lengths > 0) {
1082       double cards_per_entry_ratio =
1083         (double) cards_scanned / (double) _max_rs_lengths;
1084       if (collector_state()->last_gc_was_young()) {
1085         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1086       } else {
1087         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1088       }
1089     }
1090 
1091     // This is defensive. For a while _max_rs_lengths could get
1092     // smaller than _recorded_rs_lengths which was causing
1093     // rs_length_diff to get very large and mess up the RSet length
1094     // predictions. The reason was unsafe concurrent updates to the
1095     // _inc_cset_recorded_rs_lengths field which the code below guards
1096     // against (see CR 7118202). This bug has now been fixed (see CR
1097     // 7119027). However, I'm still worried that
1098     // _inc_cset_recorded_rs_lengths might still end up somewhat
1099     // inaccurate. The concurrent refinement thread calculates an
1100     // RSet's length concurrently with other CR threads updating it
1101     // which might cause it to calculate the length incorrectly (if,
1102     // say, it's in mid-coarsening). So I'll leave in the defensive
1103     // conditional below just in case.
1104     size_t rs_length_diff = 0;
1105     if (_max_rs_lengths > _recorded_rs_lengths) {
1106       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1107     }
1108     _rs_length_diff_seq->add((double) rs_length_diff);
1109 
1110     size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1111     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1112     double cost_per_byte_ms = 0.0;
1113 
1114     if (copied_bytes > 0) {
1115       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1116       if (collector_state()->in_marking_window()) {
1117         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1118       } else {
1119         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1120       }
1121     }
1122 
1123     if (young_cset_region_length() > 0) {
1124       _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1125                                                young_cset_region_length());
1126     }
1127 
1128     if (old_cset_region_length() > 0) {
1129       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1130                                                    old_cset_region_length());
1131     }
1132 
1133     _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1134 
1135     _pending_cards_seq->add((double) _pending_cards);
1136     _rs_lengths_seq->add((double) _max_rs_lengths);
1137   }
1138 
1139   collector_state()->set_in_marking_window(new_in_marking_window);
1140   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1141   _free_regions_at_end_of_collection = _g1->num_free_regions();
1142   update_young_list_max_and_target_length();
1143   update_rs_lengths_prediction();
1144 
1145   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1146   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1147 
1148   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1149 
1150   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1151     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
1152                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
1153                                 update_rs_time_goal_ms, scan_hcc_time_ms);
1154 
1155     update_rs_time_goal_ms = 0;
1156   } else {
1157     update_rs_time_goal_ms -= scan_hcc_time_ms;
1158   }
1159   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1160                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1161                                update_rs_time_goal_ms);
1162 
1163   _collectionSetChooser->verify();
1164 }
1165 
1166 #define EXT_SIZE_FORMAT "%.1f%s"
1167 #define EXT_SIZE_PARAMS(bytes)                                  \
1168   byte_size_in_proper_unit((double)(bytes)),                    \
1169   proper_unit_for_byte_size((bytes))
1170 
1171 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1172   YoungList* young_list = _g1->young_list();
1173   _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1174   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1175   _heap_capacity_bytes_before_gc = _g1->capacity();
1176   _heap_used_bytes_before_gc = _g1->used();
1177   _old_used_bytes_before_gc = _heap_used_bytes_before_gc - _survivor_used_bytes_before_gc - _eden_used_bytes_before_gc;
1178   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1179 
1180   _eden_capacity_bytes_before_gc =
1181          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1182 
1183   _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1184 }
1185 
1186 void G1CollectorPolicy::print_detailed_heap_transition() const {
1187   YoungList* young_list = _g1->young_list();
1188 
1189   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1190   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1191   size_t old_used_bytes_after_gc = _g1->used() - eden_used_bytes_after_gc - survivor_used_bytes_after_gc;
1192 
1193   size_t heap_capacity_bytes_after_gc = _g1->capacity();
1194   size_t eden_capacity_bytes_after_gc =
1195     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1196   size_t survivor_capacity_bytes_after_gc = _max_survivor_regions * HeapRegion::GrainBytes;
1197 
1198   log_info(gc, heap)("Eden: " SIZE_FORMAT "K->" SIZE_FORMAT "K("  SIZE_FORMAT "K)",
1199       _eden_used_bytes_before_gc / K, eden_used_bytes_after_gc /K, eden_capacity_bytes_after_gc /K);
1200 
1201   log_info(gc, heap)("Survivor: " SIZE_FORMAT "K->" SIZE_FORMAT "K("  SIZE_FORMAT "K)",
1202       _survivor_used_bytes_before_gc / K, survivor_used_bytes_after_gc /K, survivor_capacity_bytes_after_gc /K);
1203 
1204   log_info(gc, heap)("Old: " SIZE_FORMAT "K->" SIZE_FORMAT "K("  SIZE_FORMAT "K)",
1205       _old_used_bytes_before_gc / K, old_used_bytes_after_gc /K, heap_capacity_bytes_after_gc /K);
1206 
1207   MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1208 }
1209 
1210 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1211   phase_times()->print(pause_time_sec);
1212 }
1213 
1214 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1215                                                      double update_rs_processed_buffers,
1216                                                      double goal_ms) {
1217   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1218   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1219 
1220   if (G1UseAdaptiveConcRefinement) {
1221     const int k_gy = 3, k_gr = 6;
1222     const double inc_k = 1.1, dec_k = 0.9;
1223 
1224     int g = cg1r->green_zone();
1225     if (update_rs_time > goal_ms) {
1226       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1227     } else {
1228       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1229         g = (int)MAX2(g * inc_k, g + 1.0);
1230       }
1231     }
1232     // Change the refinement threads params
1233     cg1r->set_green_zone(g);
1234     cg1r->set_yellow_zone(g * k_gy);
1235     cg1r->set_red_zone(g * k_gr);
1236     cg1r->reinitialize_threads();
1237 
1238     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1239     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1240                                     cg1r->yellow_zone());
1241     // Change the barrier params
1242     dcqs.set_process_completed_threshold(processing_threshold);
1243     dcqs.set_max_completed_queue(cg1r->red_zone());
1244   }
1245 
1246   int curr_queue_size = dcqs.completed_buffers_num();
1247   if (curr_queue_size >= cg1r->yellow_zone()) {
1248     dcqs.set_completed_queue_padding(curr_queue_size);
1249   } else {
1250     dcqs.set_completed_queue_padding(0);
1251   }
1252   dcqs.notify_if_necessary();
1253 }
1254 
1255 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1256   return (size_t) get_new_prediction(_rs_length_diff_seq);
1257 }
1258 
1259 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1260   return get_new_prediction(_alloc_rate_ms_seq);
1261 }
1262 
1263 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1264   return get_new_prediction(_cost_per_card_ms_seq);
1265 }
1266 
1267 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1268   return get_new_prediction(_cost_scan_hcc_seq);
1269 }
1270 
1271 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1272   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1273 }
1274 
1275 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1276   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1277 }
1278 
1279 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1280   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1281     return predict_young_cards_per_entry_ratio();
1282   } else {
1283     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1284   }
1285 }
1286 
1287 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1288   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1289 }
1290 
1291 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1292   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1293 }
1294 
1295 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1296   if (collector_state()->gcs_are_young()) {
1297     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1298   } else {
1299     return predict_mixed_rs_scan_time_ms(card_num);
1300   }
1301 }
1302 
1303 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1304   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1305     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1306   } else {
1307     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1308   }
1309 }
1310 
1311 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1312   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1313     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1314   } else {
1315     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1316   }
1317 }
1318 
1319 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1320   if (collector_state()->during_concurrent_mark()) {
1321     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1322   } else {
1323     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1324   }
1325 }
1326 
1327 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1328   return get_new_prediction(_constant_other_time_ms_seq);
1329 }
1330 
1331 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1332   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1333 }
1334 
1335 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1336   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1337 }
1338 
1339 double G1CollectorPolicy::predict_remark_time_ms() const {
1340   return get_new_prediction(_concurrent_mark_remark_times_ms);
1341 }
1342 
1343 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1344   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1345 }
1346 
1347 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1348   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1349   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1350   double pred = get_new_prediction(seq);
1351   if (pred > 1.0) {
1352     pred = 1.0;
1353   }
1354   return pred;
1355 }
1356 
1357 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1358   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1359 }
1360 
1361 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1362   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1363 }
1364 
1365 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1366                                                        size_t scanned_cards) const {
1367   return
1368     predict_rs_update_time_ms(pending_cards) +
1369     predict_rs_scan_time_ms(scanned_cards) +
1370     predict_constant_other_time_ms();
1371 }
1372 
1373 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1374   size_t rs_length = predict_rs_length_diff();
1375   size_t card_num;
1376   if (collector_state()->gcs_are_young()) {
1377     card_num = predict_young_card_num(rs_length);
1378   } else {
1379     card_num = predict_non_young_card_num(rs_length);
1380   }
1381   return predict_base_elapsed_time_ms(pending_cards, card_num);
1382 }
1383 
1384 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1385   size_t bytes_to_copy;
1386   if (hr->is_marked())
1387     bytes_to_copy = hr->max_live_bytes();
1388   else {
1389     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1390     int age = hr->age_in_surv_rate_group();
1391     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1392     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1393   }
1394   return bytes_to_copy;
1395 }
1396 
1397 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1398                                                          bool for_young_gc) const {
1399   size_t rs_length = hr->rem_set()->occupied();
1400   size_t card_num;
1401 
1402   // Predicting the number of cards is based on which type of GC
1403   // we're predicting for.
1404   if (for_young_gc) {
1405     card_num = predict_young_card_num(rs_length);
1406   } else {
1407     card_num = predict_non_young_card_num(rs_length);
1408   }
1409   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1410 
1411   double region_elapsed_time_ms =
1412     predict_rs_scan_time_ms(card_num) +
1413     predict_object_copy_time_ms(bytes_to_copy);
1414 
1415   // The prediction of the "other" time for this region is based
1416   // upon the region type and NOT the GC type.
1417   if (hr->is_young()) {
1418     region_elapsed_time_ms += predict_young_other_time_ms(1);
1419   } else {
1420     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1421   }
1422   return region_elapsed_time_ms;
1423 }
1424 
1425 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1426                                                  uint survivor_cset_region_length) {
1427   _eden_cset_region_length     = eden_cset_region_length;
1428   _survivor_cset_region_length = survivor_cset_region_length;
1429   _old_cset_region_length      = 0;
1430 }
1431 
1432 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1433   _recorded_rs_lengths = rs_lengths;
1434 }
1435 
1436 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1437                                                double elapsed_ms) {
1438   _recent_gc_times_ms->add(elapsed_ms);
1439   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1440   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1441 }
1442 
1443 size_t G1CollectorPolicy::expansion_amount() const {
1444   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1445   double threshold = _gc_overhead_perc;
1446   if (recent_gc_overhead > threshold) {
1447     // We will double the existing space, or take
1448     // G1ExpandByPercentOfAvailable % of the available expansion
1449     // space, whichever is smaller, bounded below by a minimum
1450     // expansion (unless that's all that's left.)
1451     const size_t min_expand_bytes = 1*M;
1452     size_t reserved_bytes = _g1->max_capacity();
1453     size_t committed_bytes = _g1->capacity();
1454     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1455     size_t expand_bytes;
1456     size_t expand_bytes_via_pct =
1457       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1458     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1459     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1460     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1461 
1462     log_debug(gc, ergo, heap)("Attempt heap expansion (recent GC overhead higher than threshold after GC) "
1463                               "recent GC overhead: %1.2f %% threshold: %1.2f %% uncommitted: " SIZE_FORMAT "B calculated expansion amount: " SIZE_FORMAT "B (" INTX_FORMAT "%%)",
1464                               recent_gc_overhead, threshold, uncommitted_bytes, expand_bytes_via_pct, G1ExpandByPercentOfAvailable);
1465 
1466     return expand_bytes;
1467   } else {
1468     return 0;
1469   }
1470 }
1471 
1472 void G1CollectorPolicy::print_tracing_info() const {
1473   _trace_young_gen_time_data.print();
1474   _trace_old_gen_time_data.print();
1475 }
1476 
1477 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1478 #ifndef PRODUCT
1479   _short_lived_surv_rate_group->print_surv_rate_summary();
1480   // add this call for any other surv rate groups
1481 #endif // PRODUCT
1482 }
1483 
1484 bool G1CollectorPolicy::is_young_list_full() const {
1485   uint young_list_length = _g1->young_list()->length();
1486   uint young_list_target_length = _young_list_target_length;
1487   return young_list_length >= young_list_target_length;
1488 }
1489 
1490 bool G1CollectorPolicy::can_expand_young_list() const {
1491   uint young_list_length = _g1->young_list()->length();
1492   uint young_list_max_length = _young_list_max_length;
1493   return young_list_length < young_list_max_length;
1494 }
1495 
1496 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1497   uint expansion_region_num = 0;
1498   if (GCLockerEdenExpansionPercent > 0) {
1499     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1500     double expansion_region_num_d = perc * (double) _young_list_target_length;
1501     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1502     // less than 1.0) we'll get 1.
1503     expansion_region_num = (uint) ceil(expansion_region_num_d);
1504   } else {
1505     assert(expansion_region_num == 0, "sanity");
1506   }
1507   _young_list_max_length = _young_list_target_length + expansion_region_num;
1508   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1509 }
1510 
1511 // Calculates survivor space parameters.
1512 void G1CollectorPolicy::update_survivors_policy() {
1513   double max_survivor_regions_d =
1514                  (double) _young_list_target_length / (double) SurvivorRatio;
1515   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1516   // smaller than 1.0) we'll get 1.
1517   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1518 
1519   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1520         HeapRegion::GrainWords * _max_survivor_regions, counters());
1521 }
1522 
1523 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1524   // We actually check whether we are marking here and not if we are in a
1525   // reclamation phase. This means that we will schedule a concurrent mark
1526   // even while we are still in the process of reclaiming memory.
1527   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1528   if (!during_cycle) {
1529     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
1530     collector_state()->set_initiate_conc_mark_if_possible(true);
1531     return true;
1532   } else {
1533     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
1534     return false;
1535   }
1536 }
1537 
1538 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1539   // We are about to decide on whether this pause will be an
1540   // initial-mark pause.
1541 
1542   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1543   // will set it here if we have to. However, it should be cleared by
1544   // the end of the pause (it's only set for the duration of an
1545   // initial-mark pause).
1546   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1547 
1548   if (collector_state()->initiate_conc_mark_if_possible()) {
1549     // We had noticed on a previous pause that the heap occupancy has
1550     // gone over the initiating threshold and we should start a
1551     // concurrent marking cycle. So we might initiate one.
1552 
1553     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1554       // Initiate a new initial mark only if there is no marking or reclamation going
1555       // on.
1556 
1557       collector_state()->set_during_initial_mark_pause(true);
1558       // And we can now clear initiate_conc_mark_if_possible() as
1559       // we've already acted on it.
1560       collector_state()->set_initiate_conc_mark_if_possible(false);
1561 
1562       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
1563     } else {
1564       // The concurrent marking thread is still finishing up the
1565       // previous cycle. If we start one right now the two cycles
1566       // overlap. In particular, the concurrent marking thread might
1567       // be in the process of clearing the next marking bitmap (which
1568       // we will use for the next cycle if we start one). Starting a
1569       // cycle now will be bad given that parts of the marking
1570       // information might get cleared by the marking thread. And we
1571       // cannot wait for the marking thread to finish the cycle as it
1572       // periodically yields while clearing the next marking bitmap
1573       // and, if it's in a yield point, it's waiting for us to
1574       // finish. So, at this point we will not start a cycle and we'll
1575       // let the concurrent marking thread complete the last one.
1576       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
1577     }
1578   }
1579 }
1580 
1581 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1582   G1CollectedHeap* _g1h;
1583   CSetChooserParUpdater _cset_updater;
1584 
1585 public:
1586   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1587                            uint chunk_size) :
1588     _g1h(G1CollectedHeap::heap()),
1589     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1590 
1591   bool doHeapRegion(HeapRegion* r) {
1592     // Do we have any marking information for this region?
1593     if (r->is_marked()) {
1594       // We will skip any region that's currently used as an old GC
1595       // alloc region (we should not consider those for collection
1596       // before we fill them up).
1597       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1598         _cset_updater.add_region(r);
1599       }
1600     }
1601     return false;
1602   }
1603 };
1604 
1605 class ParKnownGarbageTask: public AbstractGangTask {
1606   CollectionSetChooser* _hrSorted;
1607   uint _chunk_size;
1608   G1CollectedHeap* _g1;
1609   HeapRegionClaimer _hrclaimer;
1610 
1611 public:
1612   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1613       AbstractGangTask("ParKnownGarbageTask"),
1614       _hrSorted(hrSorted), _chunk_size(chunk_size),
1615       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1616 
1617   void work(uint worker_id) {
1618     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1619     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1620   }
1621 };
1622 
1623 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1624   assert(n_workers > 0, "Active gc workers should be greater than 0");
1625   const uint overpartition_factor = 4;
1626   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1627   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1628 }
1629 
1630 void
1631 G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1632   _collectionSetChooser->clear();
1633 
1634   WorkGang* workers = _g1->workers();
1635   uint n_workers = workers->active_workers();
1636 
1637   uint n_regions = _g1->num_regions();
1638   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1639   _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1640   ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1641   workers->run_task(&par_known_garbage_task);
1642 
1643   _collectionSetChooser->sort_regions();
1644 
1645   double end_sec = os::elapsedTime();
1646   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1647   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1648   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1649   _prev_collection_pause_end_ms += elapsed_time_ms;
1650   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec);
1651 }
1652 
1653 // Add the heap region at the head of the non-incremental collection set
1654 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1655   assert(_inc_cset_build_state == Active, "Precondition");
1656   assert(hr->is_old(), "the region should be old");
1657 
1658   assert(!hr->in_collection_set(), "should not already be in the CSet");
1659   _g1->register_old_region_with_cset(hr);
1660   hr->set_next_in_collection_set(_collection_set);
1661   _collection_set = hr;
1662   _collection_set_bytes_used_before += hr->used();
1663   size_t rs_length = hr->rem_set()->occupied();
1664   _recorded_rs_lengths += rs_length;
1665   _old_cset_region_length += 1;
1666 }
1667 
1668 // Initialize the per-collection-set information
1669 void G1CollectorPolicy::start_incremental_cset_building() {
1670   assert(_inc_cset_build_state == Inactive, "Precondition");
1671 
1672   _inc_cset_head = NULL;
1673   _inc_cset_tail = NULL;
1674   _inc_cset_bytes_used_before = 0;
1675 
1676   _inc_cset_max_finger = 0;
1677   _inc_cset_recorded_rs_lengths = 0;
1678   _inc_cset_recorded_rs_lengths_diffs = 0;
1679   _inc_cset_predicted_elapsed_time_ms = 0.0;
1680   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1681   _inc_cset_build_state = Active;
1682 }
1683 
1684 void G1CollectorPolicy::finalize_incremental_cset_building() {
1685   assert(_inc_cset_build_state == Active, "Precondition");
1686   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1687 
1688   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1689   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1690   // that adds a new region to the CSet. Further updates by the
1691   // concurrent refinement thread that samples the young RSet lengths
1692   // are accumulated in the *_diffs fields. Here we add the diffs to
1693   // the "main" fields.
1694 
1695   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1696     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1697   } else {
1698     // This is defensive. The diff should in theory be always positive
1699     // as RSets can only grow between GCs. However, given that we
1700     // sample their size concurrently with other threads updating them
1701     // it's possible that we might get the wrong size back, which
1702     // could make the calculations somewhat inaccurate.
1703     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1704     if (_inc_cset_recorded_rs_lengths >= diffs) {
1705       _inc_cset_recorded_rs_lengths -= diffs;
1706     } else {
1707       _inc_cset_recorded_rs_lengths = 0;
1708     }
1709   }
1710   _inc_cset_predicted_elapsed_time_ms +=
1711                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1712 
1713   _inc_cset_recorded_rs_lengths_diffs = 0;
1714   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1715 }
1716 
1717 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1718   // This routine is used when:
1719   // * adding survivor regions to the incremental cset at the end of an
1720   //   evacuation pause,
1721   // * adding the current allocation region to the incremental cset
1722   //   when it is retired, and
1723   // * updating existing policy information for a region in the
1724   //   incremental cset via young list RSet sampling.
1725   // Therefore this routine may be called at a safepoint by the
1726   // VM thread, or in-between safepoints by mutator threads (when
1727   // retiring the current allocation region) or a concurrent
1728   // refine thread (RSet sampling).
1729 
1730   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1731   size_t used_bytes = hr->used();
1732   _inc_cset_recorded_rs_lengths += rs_length;
1733   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1734   _inc_cset_bytes_used_before += used_bytes;
1735 
1736   // Cache the values we have added to the aggregated information
1737   // in the heap region in case we have to remove this region from
1738   // the incremental collection set, or it is updated by the
1739   // rset sampling code
1740   hr->set_recorded_rs_length(rs_length);
1741   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1742 }
1743 
1744 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1745                                                      size_t new_rs_length) {
1746   // Update the CSet information that is dependent on the new RS length
1747   assert(hr->is_young(), "Precondition");
1748   assert(!SafepointSynchronize::is_at_safepoint(),
1749                                                "should not be at a safepoint");
1750 
1751   // We could have updated _inc_cset_recorded_rs_lengths and
1752   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1753   // that atomically, as this code is executed by a concurrent
1754   // refinement thread, potentially concurrently with a mutator thread
1755   // allocating a new region and also updating the same fields. To
1756   // avoid the atomic operations we accumulate these updates on two
1757   // separate fields (*_diffs) and we'll just add them to the "main"
1758   // fields at the start of a GC.
1759 
1760   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1761   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1762   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1763 
1764   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1765   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1766   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1767   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1768 
1769   hr->set_recorded_rs_length(new_rs_length);
1770   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1771 }
1772 
1773 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1774   assert(hr->is_young(), "invariant");
1775   assert(hr->young_index_in_cset() > -1, "should have already been set");
1776   assert(_inc_cset_build_state == Active, "Precondition");
1777 
1778   // We need to clear and set the cached recorded/cached collection set
1779   // information in the heap region here (before the region gets added
1780   // to the collection set). An individual heap region's cached values
1781   // are calculated, aggregated with the policy collection set info,
1782   // and cached in the heap region here (initially) and (subsequently)
1783   // by the Young List sampling code.
1784 
1785   size_t rs_length = hr->rem_set()->occupied();
1786   add_to_incremental_cset_info(hr, rs_length);
1787 
1788   HeapWord* hr_end = hr->end();
1789   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1790 
1791   assert(!hr->in_collection_set(), "invariant");
1792   _g1->register_young_region_with_cset(hr);
1793   assert(hr->next_in_collection_set() == NULL, "invariant");
1794 }
1795 
1796 // Add the region at the RHS of the incremental cset
1797 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1798   // We should only ever be appending survivors at the end of a pause
1799   assert(hr->is_survivor(), "Logic");
1800 
1801   // Do the 'common' stuff
1802   add_region_to_incremental_cset_common(hr);
1803 
1804   // Now add the region at the right hand side
1805   if (_inc_cset_tail == NULL) {
1806     assert(_inc_cset_head == NULL, "invariant");
1807     _inc_cset_head = hr;
1808   } else {
1809     _inc_cset_tail->set_next_in_collection_set(hr);
1810   }
1811   _inc_cset_tail = hr;
1812 }
1813 
1814 // Add the region to the LHS of the incremental cset
1815 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1816   // Survivors should be added to the RHS at the end of a pause
1817   assert(hr->is_eden(), "Logic");
1818 
1819   // Do the 'common' stuff
1820   add_region_to_incremental_cset_common(hr);
1821 
1822   // Add the region at the left hand side
1823   hr->set_next_in_collection_set(_inc_cset_head);
1824   if (_inc_cset_head == NULL) {
1825     assert(_inc_cset_tail == NULL, "Invariant");
1826     _inc_cset_tail = hr;
1827   }
1828   _inc_cset_head = hr;
1829 }
1830 
1831 #ifndef PRODUCT
1832 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1833   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1834 
1835   st->print_cr("\nCollection_set:");
1836   HeapRegion* csr = list_head;
1837   while (csr != NULL) {
1838     HeapRegion* next = csr->next_in_collection_set();
1839     assert(csr->in_collection_set(), "bad CS");
1840     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
1841                  HR_FORMAT_PARAMS(csr),
1842                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
1843                  csr->age_in_surv_rate_group_cond());
1844     csr = next;
1845   }
1846 }
1847 #endif // !PRODUCT
1848 
1849 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
1850   // Returns the given amount of reclaimable bytes (that represents
1851   // the amount of reclaimable space still to be collected) as a
1852   // percentage of the current heap capacity.
1853   size_t capacity_bytes = _g1->capacity();
1854   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1855 }
1856 
1857 void G1CollectorPolicy::maybe_start_marking() {
1858   if (need_to_start_conc_mark("end of GC")) {
1859     // Note: this might have already been set, if during the last
1860     // pause we decided to start a cycle but at the beginning of
1861     // this pause we decided to postpone it. That's OK.
1862     collector_state()->set_initiate_conc_mark_if_possible(true);
1863   }
1864 }
1865 
1866 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1867                                                 const char* false_action_str) const {
1868   CollectionSetChooser* cset_chooser = _collectionSetChooser;
1869   if (cset_chooser->is_empty()) {
1870     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
1871     return false;
1872   }
1873 
1874   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1875   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1876   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1877   double threshold = (double) G1HeapWastePercent;
1878   if (reclaimable_perc <= threshold) {
1879     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1880                         false_action_str, cset_chooser->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1881     return false;
1882   }
1883 
1884   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1885                       true_action_str, cset_chooser->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1886   return true;
1887 }
1888 
1889 uint G1CollectorPolicy::calc_min_old_cset_length() const {
1890   // The min old CSet region bound is based on the maximum desired
1891   // number of mixed GCs after a cycle. I.e., even if some old regions
1892   // look expensive, we should add them to the CSet anyway to make
1893   // sure we go through the available old regions in no more than the
1894   // maximum desired number of mixed GCs.
1895   //
1896   // The calculation is based on the number of marked regions we added
1897   // to the CSet chooser in the first place, not how many remain, so
1898   // that the result is the same during all mixed GCs that follow a cycle.
1899 
1900   const size_t region_num = (size_t) _collectionSetChooser->length();
1901   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1902   size_t result = region_num / gc_num;
1903   // emulate ceiling
1904   if (result * gc_num < region_num) {
1905     result += 1;
1906   }
1907   return (uint) result;
1908 }
1909 
1910 uint G1CollectorPolicy::calc_max_old_cset_length() const {
1911   // The max old CSet region bound is based on the threshold expressed
1912   // as a percentage of the heap size. I.e., it should bound the
1913   // number of old regions added to the CSet irrespective of how many
1914   // of them are available.
1915 
1916   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
1917   const size_t region_num = g1h->num_regions();
1918   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1919   size_t result = region_num * perc / 100;
1920   // emulate ceiling
1921   if (100 * result < region_num * perc) {
1922     result += 1;
1923   }
1924   return (uint) result;
1925 }
1926 
1927 
1928 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
1929   double young_start_time_sec = os::elapsedTime();
1930 
1931   YoungList* young_list = _g1->young_list();
1932   finalize_incremental_cset_building();
1933 
1934   guarantee(target_pause_time_ms > 0.0,
1935             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
1936   guarantee(_collection_set == NULL, "Precondition");
1937 
1938   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1939   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1940 
1941   log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
1942                             _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1943 
1944   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
1945 
1946   if (collector_state()->last_gc_was_young()) {
1947     _trace_young_gen_time_data.increment_young_collection_count();
1948   } else {
1949     _trace_young_gen_time_data.increment_mixed_collection_count();
1950   }
1951 
1952   // The young list is laid with the survivor regions from the previous
1953   // pause are appended to the RHS of the young list, i.e.
1954   //   [Newly Young Regions ++ Survivors from last pause].
1955 
1956   uint survivor_region_length = young_list->survivor_length();
1957   uint eden_region_length = young_list->eden_length();
1958   init_cset_region_lengths(eden_region_length, survivor_region_length);
1959 
1960   HeapRegion* hr = young_list->first_survivor_region();
1961   while (hr != NULL) {
1962     assert(hr->is_survivor(), "badly formed young list");
1963     // There is a convention that all the young regions in the CSet
1964     // are tagged as "eden", so we do this for the survivors here. We
1965     // use the special set_eden_pre_gc() as it doesn't check that the
1966     // region is free (which is not the case here).
1967     hr->set_eden_pre_gc();
1968     hr = hr->get_next_young_region();
1969   }
1970 
1971   // Clear the fields that point to the survivor list - they are all young now.
1972   young_list->clear_survivors();
1973 
1974   _collection_set = _inc_cset_head;
1975   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1976   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1977 
1978   log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
1979                             eden_region_length, survivor_region_length, _inc_cset_predicted_elapsed_time_ms, target_pause_time_ms);
1980 
1981   // The number of recorded young regions is the incremental
1982   // collection set's current size
1983   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1984 
1985   double young_end_time_sec = os::elapsedTime();
1986   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1987 
1988   return time_remaining_ms;
1989 }
1990 
1991 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
1992   double non_young_start_time_sec = os::elapsedTime();
1993   double predicted_old_time_ms = 0.0;
1994 
1995 
1996   if (!collector_state()->gcs_are_young()) {
1997     CollectionSetChooser* cset_chooser = _collectionSetChooser;
1998     cset_chooser->verify();
1999     const uint min_old_cset_length = calc_min_old_cset_length();
2000     const uint max_old_cset_length = calc_max_old_cset_length();
2001 
2002     uint expensive_region_num = 0;
2003     bool check_time_remaining = adaptive_young_list_length();
2004 
2005     HeapRegion* hr = cset_chooser->peek();
2006     while (hr != NULL) {
2007       if (old_cset_region_length() >= max_old_cset_length) {
2008         // Added maximum number of old regions to the CSet.
2009         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). old %u regions, max %u regions",
2010                                   old_cset_region_length(), max_old_cset_length);
2011         break;
2012       }
2013 
2014 
2015       // Stop adding regions if the remaining reclaimable space is
2016       // not above G1HeapWastePercent.
2017       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2018       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2019       double threshold = (double) G1HeapWastePercent;
2020       if (reclaimable_perc <= threshold) {
2021         // We've added enough old regions that the amount of uncollected
2022         // reclaimable space is at or below the waste threshold. Stop
2023         // adding old regions to the CSet.
2024         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). "
2025                                   "old %u regions, max %u regions, reclaimable: " SIZE_FORMAT "B (%1.2f%%) threshold: " UINTX_FORMAT "%%",
2026                                   old_cset_region_length(), max_old_cset_length, reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2027         break;
2028       }
2029 
2030       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2031       if (check_time_remaining) {
2032         if (predicted_time_ms > time_remaining_ms) {
2033           // Too expensive for the current CSet.
2034 
2035           if (old_cset_region_length() >= min_old_cset_length) {
2036             // We have added the minimum number of old regions to the CSet,
2037             // we are done with this CSet.
2038             log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high). "
2039                                       "predicted time: %1.2fms, remaining time: %1.2fms old %u regions, min %u regions",
2040                                       predicted_time_ms, time_remaining_ms, old_cset_region_length(), min_old_cset_length);
2041             break;
2042           }
2043 
2044           // We'll add it anyway given that we haven't reached the
2045           // minimum number of old regions.
2046           expensive_region_num += 1;
2047         }
2048       } else {
2049         if (old_cset_region_length() >= min_old_cset_length) {
2050           // In the non-auto-tuning case, we'll finish adding regions
2051           // to the CSet if we reach the minimum.
2052 
2053           log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min). old %u regions, min %u regions",
2054                                     old_cset_region_length(), min_old_cset_length);
2055           break;
2056         }
2057       }
2058 
2059       // We will add this region to the CSet.
2060       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2061       predicted_old_time_ms += predicted_time_ms;
2062       cset_chooser->pop(); // already have region via peek()
2063       _g1->old_set_remove(hr);
2064       add_old_region_to_cset(hr);
2065 
2066       hr = cset_chooser->peek();
2067     }
2068     if (hr == NULL) {
2069       log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)");
2070     }
2071 
2072     if (expensive_region_num > 0) {
2073       // We print the information once here at the end, predicated on
2074       // whether we added any apparently expensive regions or not, to
2075       // avoid generating output per region.
2076       log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
2077                                 "old %u regions, expensive: %u regions, min %u regions, remaining time: %1.2fms",
2078                                 old_cset_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
2079     }
2080 
2081     cset_chooser->verify();
2082   }
2083 
2084   stop_incremental_cset_building();
2085 
2086   log_debug(gc, ergo, cset)("Finish choosing CSet. old %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
2087                             old_cset_region_length(), predicted_old_time_ms, time_remaining_ms);
2088 
2089   double non_young_end_time_sec = os::elapsedTime();
2090   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2091 }
2092 
2093 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2094   if(TraceYoungGenTime) {
2095     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2096   }
2097 }
2098 
2099 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2100   if(TraceYoungGenTime) {
2101     _all_yield_times_ms.add(yield_time_ms);
2102   }
2103 }
2104 
2105 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2106   if(TraceYoungGenTime) {
2107     _total.add(pause_time_ms);
2108     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2109     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2110     _parallel.add(phase_times->cur_collection_par_time_ms());
2111     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2112     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2113     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2114     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2115     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2116     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2117 
2118     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2119       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2120       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2121       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2122       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2123       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2124 
2125     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2126     _parallel_other.add(parallel_other_time);
2127     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2128   }
2129 }
2130 
2131 void TraceYoungGenTimeData::increment_young_collection_count() {
2132   if(TraceYoungGenTime) {
2133     ++_young_pause_num;
2134   }
2135 }
2136 
2137 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2138   if(TraceYoungGenTime) {
2139     ++_mixed_pause_num;
2140   }
2141 }
2142 
2143 void TraceYoungGenTimeData::print_summary(const char* str,
2144                                           const NumberSeq* seq) const {
2145   double sum = seq->sum();
2146   tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2147                 str, sum / 1000.0, seq->avg());
2148 }
2149 
2150 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2151                                              const NumberSeq* seq) const {
2152   print_summary(str, seq);
2153   tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2154                 "(num", seq->num(), seq->sd(), seq->maximum());
2155 }
2156 
2157 void TraceYoungGenTimeData::print() const {
2158   if (!TraceYoungGenTime) {
2159     return;
2160   }
2161 
2162   tty->print_cr("ALL PAUSES");
2163   print_summary_sd("   Total", &_total);
2164   tty->cr();
2165   tty->cr();
2166   tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2167   tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2168   tty->cr();
2169 
2170   tty->print_cr("EVACUATION PAUSES");
2171 
2172   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2173     tty->print_cr("none");
2174   } else {
2175     print_summary_sd("   Evacuation Pauses", &_total);
2176     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2177     print_summary("      Parallel Time", &_parallel);
2178     print_summary("         Ext Root Scanning", &_ext_root_scan);
2179     print_summary("         SATB Filtering", &_satb_filtering);
2180     print_summary("         Update RS", &_update_rs);
2181     print_summary("         Scan RS", &_scan_rs);
2182     print_summary("         Object Copy", &_obj_copy);
2183     print_summary("         Termination", &_termination);
2184     print_summary("         Parallel Other", &_parallel_other);
2185     print_summary("      Clear CT", &_clear_ct);
2186     print_summary("      Other", &_other);
2187   }
2188   tty->cr();
2189 
2190   tty->print_cr("MISC");
2191   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2192   print_summary_sd("   Yields", &_all_yield_times_ms);
2193 }
2194 
2195 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2196   if (TraceOldGenTime) {
2197     _all_full_gc_times.add(full_gc_time_ms);
2198   }
2199 }
2200 
2201 void TraceOldGenTimeData::print() const {
2202   if (!TraceOldGenTime) {
2203     return;
2204   }
2205 
2206   if (_all_full_gc_times.num() > 0) {
2207     tty->print("\n%4d full_gcs: total time = %8.2f s",
2208       _all_full_gc_times.num(),
2209       _all_full_gc_times.sum() / 1000.0);
2210     tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2211     tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2212       _all_full_gc_times.sd(),
2213       _all_full_gc_times.maximum());
2214   }
2215 }