1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/concurrentMark.hpp"
  28 #include "gc/g1/concurrentMarkThread.inline.hpp"
  29 #include "gc/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc/g1/g1CollectorPolicy.hpp"
  31 #include "gc/g1/g1ErgoVerbose.hpp"
  32 #include "gc/g1/g1GCPhaseTimes.hpp"
  33 #include "gc/g1/g1Log.hpp"
  34 #include "gc/g1/heapRegion.inline.hpp"
  35 #include "gc/g1/heapRegionRemSet.hpp"
  36 #include "gc/shared/gcPolicyCounters.hpp"
  37 #include "runtime/arguments.hpp"
  38 #include "runtime/java.hpp"
  39 #include "runtime/mutexLocker.hpp"
  40 #include "utilities/debug.hpp"
  41 
  42 // Different defaults for different number of GC threads
  43 // They were chosen by running GCOld and SPECjbb on debris with different
  44 //   numbers of GC threads and choosing them based on the results
  45 
  46 // all the same
  47 static double rs_length_diff_defaults[] = {
  48   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
  49 };
  50 
  51 static double cost_per_card_ms_defaults[] = {
  52   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
  53 };
  54 
  55 // all the same
  56 static double young_cards_per_entry_ratio_defaults[] = {
  57   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
  58 };
  59 
  60 static double cost_per_entry_ms_defaults[] = {
  61   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
  62 };
  63 
  64 static double cost_per_byte_ms_defaults[] = {
  65   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
  66 };
  67 
  68 // these should be pretty consistent
  69 static double constant_other_time_ms_defaults[] = {
  70   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
  71 };
  72 
  73 
  74 static double young_other_cost_per_region_ms_defaults[] = {
  75   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
  76 };
  77 
  78 static double non_young_other_cost_per_region_ms_defaults[] = {
  79   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
  80 };
  81 
  82 G1CollectorPolicy::G1CollectorPolicy() :
  83   _predictor(G1ConfidencePercent / 100.0),
  84   _parallel_gc_threads(ParallelGCThreads),
  85 
  86   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  87   _stop_world_start(0.0),
  88 
  89   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  90   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  91 
  92   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  93   _prev_collection_pause_end_ms(0.0),
  94   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 105   _non_young_other_cost_per_region_ms_seq(
 106                                          new TruncatedSeq(TruncatedSeqLength)),
 107 
 108   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 109   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 110 
 111   _pause_time_target_ms((double) MaxGCPauseMillis),
 112 
 113   _recent_prev_end_times_for_all_gcs_sec(
 114                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 115 
 116   _recent_avg_pause_time_ratio(0.0),
 117   _rs_lengths_prediction(0),
 118   _max_survivor_regions(0),
 119 
 120   _eden_used_bytes_before_gc(0),
 121   _survivor_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   G1ErgoVerbose::initialize();
 175   if (PrintAdaptiveSizePolicy) {
 176     // Currently, we only use a single switch for all the heuristics.
 177     G1ErgoVerbose::set_enabled(true);
 178     // Given that we don't currently have a verboseness level
 179     // parameter, we'll hardcode this to high. This can be easily
 180     // changed in the future.
 181     G1ErgoVerbose::set_level(ErgoHigh);
 182   } else {
 183     G1ErgoVerbose::set_enabled(false);
 184   }
 185 
 186   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 187   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 188 
 189   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 190 
 191   int index = MIN2(_parallel_gc_threads - 1, 7);
 192 
 193   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 194   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 195   _cost_scan_hcc_seq->add(0.0);
 196   _young_cards_per_entry_ratio_seq->add(
 197                                   young_cards_per_entry_ratio_defaults[index]);
 198   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 199   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 200   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 201   _young_other_cost_per_region_ms_seq->add(
 202                                young_other_cost_per_region_ms_defaults[index]);
 203   _non_young_other_cost_per_region_ms_seq->add(
 204                            non_young_other_cost_per_region_ms_defaults[index]);
 205 
 206   // Below, we might need to calculate the pause time target based on
 207   // the pause interval. When we do so we are going to give G1 maximum
 208   // flexibility and allow it to do pauses when it needs to. So, we'll
 209   // arrange that the pause interval to be pause time target + 1 to
 210   // ensure that a) the pause time target is maximized with respect to
 211   // the pause interval and b) we maintain the invariant that pause
 212   // time target < pause interval. If the user does not want this
 213   // maximum flexibility, they will have to set the pause interval
 214   // explicitly.
 215 
 216   // First make sure that, if either parameter is set, its value is
 217   // reasonable.
 218   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 219     if (MaxGCPauseMillis < 1) {
 220       vm_exit_during_initialization("MaxGCPauseMillis should be "
 221                                     "greater than 0");
 222     }
 223   }
 224   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 225     if (GCPauseIntervalMillis < 1) {
 226       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 227                                     "greater than 0");
 228     }
 229   }
 230 
 231   // Then, if the pause time target parameter was not set, set it to
 232   // the default value.
 233   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 234     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 235       // The default pause time target in G1 is 200ms
 236       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 237     } else {
 238       // We do not allow the pause interval to be set without the
 239       // pause time target
 240       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 241                                     "without setting MaxGCPauseMillis");
 242     }
 243   }
 244 
 245   // Then, if the interval parameter was not set, set it according to
 246   // the pause time target (this will also deal with the case when the
 247   // pause time target is the default value).
 248   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 249     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 250   }
 251 
 252   // Finally, make sure that the two parameters are consistent.
 253   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 254     char buffer[256];
 255     jio_snprintf(buffer, 256,
 256                  "MaxGCPauseMillis (%u) should be less than "
 257                  "GCPauseIntervalMillis (%u)",
 258                  MaxGCPauseMillis, GCPauseIntervalMillis);
 259     vm_exit_during_initialization(buffer);
 260   }
 261 
 262   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 263   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 264   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 265 
 266   // start conservatively (around 50ms is about right)
 267   _concurrent_mark_remark_times_ms->add(0.05);
 268   _concurrent_mark_cleanup_times_ms->add(0.20);
 269   _tenuring_threshold = MaxTenuringThreshold;
 270 
 271   assert(GCTimeRatio > 0,
 272          "we should have set it to a default value set_g1_gc_flags() "
 273          "if a user set it to 0");
 274   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 275 
 276   uintx reserve_perc = G1ReservePercent;
 277   // Put an artificial ceiling on this so that it's not set to a silly value.
 278   if (reserve_perc > 50) {
 279     reserve_perc = 50;
 280     warning("G1ReservePercent is set to a value that is too large, "
 281             "it's been updated to " UINTX_FORMAT, reserve_perc);
 282   }
 283   _reserve_factor = (double) reserve_perc / 100.0;
 284   // This will be set when the heap is expanded
 285   // for the first time during initialization.
 286   _reserve_regions = 0;
 287 
 288   _collectionSetChooser = new CollectionSetChooser();
 289 }
 290 
 291 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
 292   return _predictor.get_new_prediction(seq);
 293 }
 294 
 295 void G1CollectorPolicy::initialize_alignments() {
 296   _space_alignment = HeapRegion::GrainBytes;
 297   size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
 298   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
 299   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 300 }
 301 
 302 void G1CollectorPolicy::initialize_flags() {
 303   if (G1HeapRegionSize != HeapRegion::GrainBytes) {
 304     FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
 305   }
 306 
 307   if (SurvivorRatio < 1) {
 308     vm_exit_during_initialization("Invalid survivor ratio specified");
 309   }
 310   CollectorPolicy::initialize_flags();
 311   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 312 }
 313 
 314 void G1CollectorPolicy::post_heap_initialize() {
 315   uintx max_regions = G1CollectedHeap::heap()->max_regions();
 316   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
 317   if (max_young_size != MaxNewSize) {
 318     FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
 319   }
 320 }
 321 
 322 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
 323 
 324 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
 325         _min_desired_young_length(0), _max_desired_young_length(0) {
 326   if (FLAG_IS_CMDLINE(NewRatio)) {
 327     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 328       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 329     } else {
 330       _sizer_kind = SizerNewRatio;
 331       _adaptive_size = false;
 332       return;
 333     }
 334   }
 335 
 336   if (NewSize > MaxNewSize) {
 337     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 338       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 339               "A new max generation size of " SIZE_FORMAT "k will be used.",
 340               NewSize/K, MaxNewSize/K, NewSize/K);
 341     }
 342     MaxNewSize = NewSize;
 343   }
 344 
 345   if (FLAG_IS_CMDLINE(NewSize)) {
 346     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 347                                      1U);
 348     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 349       _max_desired_young_length =
 350                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 351                                   1U);
 352       _sizer_kind = SizerMaxAndNewSize;
 353       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 354     } else {
 355       _sizer_kind = SizerNewSizeOnly;
 356     }
 357   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 358     _max_desired_young_length =
 359                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 360                                   1U);
 361     _sizer_kind = SizerMaxNewSizeOnly;
 362   }
 363 }
 364 
 365 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 366   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 367   return MAX2(1U, default_value);
 368 }
 369 
 370 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 371   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 372   return MAX2(1U, default_value);
 373 }
 374 
 375 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
 376   assert(number_of_heap_regions > 0, "Heap must be initialized");
 377 
 378   switch (_sizer_kind) {
 379     case SizerDefaults:
 380       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 381       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 382       break;
 383     case SizerNewSizeOnly:
 384       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 385       *max_young_length = MAX2(*min_young_length, *max_young_length);
 386       break;
 387     case SizerMaxNewSizeOnly:
 388       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 389       *min_young_length = MIN2(*min_young_length, *max_young_length);
 390       break;
 391     case SizerMaxAndNewSize:
 392       // Do nothing. Values set on the command line, don't update them at runtime.
 393       break;
 394     case SizerNewRatio:
 395       *min_young_length = number_of_heap_regions / (NewRatio + 1);
 396       *max_young_length = *min_young_length;
 397       break;
 398     default:
 399       ShouldNotReachHere();
 400   }
 401 
 402   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
 403 }
 404 
 405 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
 406   // We need to pass the desired values because recalculation may not update these
 407   // values in some cases.
 408   uint temp = _min_desired_young_length;
 409   uint result = _max_desired_young_length;
 410   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
 411   return result;
 412 }
 413 
 414 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 415   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
 416           &_max_desired_young_length);
 417 }
 418 
 419 void G1CollectorPolicy::init() {
 420   // Set aside an initial future to_space.
 421   _g1 = G1CollectedHeap::heap();
 422 
 423   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 424 
 425   initialize_gc_policy_counters();
 426 
 427   if (adaptive_young_list_length()) {
 428     _young_list_fixed_length = 0;
 429   } else {
 430     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 431   }
 432   _free_regions_at_end_of_collection = _g1->num_free_regions();
 433 
 434   update_young_list_max_and_target_length();
 435   // We may immediately start allocating regions and placing them on the
 436   // collection set list. Initialize the per-collection set info
 437   start_incremental_cset_building();
 438 }
 439 
 440 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
 441   phase_times()->note_gc_start(num_active_workers);
 442 }
 443 
 444 // Create the jstat counters for the policy.
 445 void G1CollectorPolicy::initialize_gc_policy_counters() {
 446   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 447 }
 448 
 449 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 450                                          double base_time_ms,
 451                                          uint base_free_regions,
 452                                          double target_pause_time_ms) const {
 453   if (young_length >= base_free_regions) {
 454     // end condition 1: not enough space for the young regions
 455     return false;
 456   }
 457 
 458   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 459   size_t bytes_to_copy =
 460                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 461   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 462   double young_other_time_ms = predict_young_other_time_ms(young_length);
 463   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 464   if (pause_time_ms > target_pause_time_ms) {
 465     // end condition 2: prediction is over the target pause time
 466     return false;
 467   }
 468 
 469   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 470   if ((2.0 /* magic */ * _predictor.sigma()) * bytes_to_copy > free_bytes) {
 471     // end condition 3: out-of-space (conservatively!)
 472     return false;
 473   }
 474 
 475   // success!
 476   return true;
 477 }
 478 
 479 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 480   // re-calculate the necessary reserve
 481   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 482   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 483   // smaller than 1.0) we'll get 1.
 484   _reserve_regions = (uint) ceil(reserve_regions_d);
 485 
 486   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 487 }
 488 
 489 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 490                                                        uint base_min_length) const {
 491   uint desired_min_length = 0;
 492   if (adaptive_young_list_length()) {
 493     if (_alloc_rate_ms_seq->num() > 3) {
 494       double now_sec = os::elapsedTime();
 495       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 496       double alloc_rate_ms = predict_alloc_rate_ms();
 497       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 498     } else {
 499       // otherwise we don't have enough info to make the prediction
 500     }
 501   }
 502   desired_min_length += base_min_length;
 503   // make sure we don't go below any user-defined minimum bound
 504   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 505 }
 506 
 507 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
 508   // Here, we might want to also take into account any additional
 509   // constraints (i.e., user-defined minimum bound). Currently, we
 510   // effectively don't set this bound.
 511   return _young_gen_sizer->max_desired_young_length();
 512 }
 513 
 514 void G1CollectorPolicy::update_young_list_max_and_target_length() {
 515   update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq));
 516 }
 517 
 518 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 519   update_young_list_target_length(rs_lengths);
 520   update_max_gc_locker_expansion();
 521 }
 522 
 523 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 524   _young_list_target_length = bounded_young_list_target_length(rs_lengths);
 525 }
 526 
 527 void G1CollectorPolicy::update_young_list_target_length() {
 528   update_young_list_target_length(get_new_prediction(_rs_lengths_seq));
 529 }
 530 
 531 uint G1CollectorPolicy::bounded_young_list_target_length(size_t rs_lengths) const {
 532   // Calculate the absolute and desired min bounds.
 533 
 534   // This is how many young regions we already have (currently: the survivors).
 535   uint base_min_length = recorded_survivor_regions();
 536   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 537   // This is the absolute minimum young length. Ensure that we
 538   // will at least have one eden region available for allocation.
 539   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 540   // If we shrank the young list target it should not shrink below the current size.
 541   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 542   // Calculate the absolute and desired max bounds.
 543 
 544   // We will try our best not to "eat" into the reserve.
 545   uint absolute_max_length = 0;
 546   if (_free_regions_at_end_of_collection > _reserve_regions) {
 547     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 548   }
 549   uint desired_max_length = calculate_young_list_desired_max_length();
 550   if (desired_max_length > absolute_max_length) {
 551     desired_max_length = absolute_max_length;
 552   }
 553 
 554   uint young_list_target_length = 0;
 555   if (adaptive_young_list_length()) {
 556     if (collector_state()->gcs_are_young()) {
 557       young_list_target_length =
 558                         calculate_young_list_target_length(rs_lengths,
 559                                                            base_min_length,
 560                                                            desired_min_length,
 561                                                            desired_max_length);
 562     } else {
 563       // Don't calculate anything and let the code below bound it to
 564       // the desired_min_length, i.e., do the next GC as soon as
 565       // possible to maximize how many old regions we can add to it.
 566     }
 567   } else {
 568     // The user asked for a fixed young gen so we'll fix the young gen
 569     // whether the next GC is young or mixed.
 570     young_list_target_length = _young_list_fixed_length;
 571   }
 572 
 573   // Make sure we don't go over the desired max length, nor under the
 574   // desired min length. In case they clash, desired_min_length wins
 575   // which is why that test is second.
 576   if (young_list_target_length > desired_max_length) {
 577     young_list_target_length = desired_max_length;
 578   }
 579   if (young_list_target_length < desired_min_length) {
 580     young_list_target_length = desired_min_length;
 581   }
 582 
 583   assert(young_list_target_length > recorded_survivor_regions(),
 584          "we should be able to allocate at least one eden region");
 585   assert(young_list_target_length >= absolute_min_length, "post-condition");
 586 
 587   return young_list_target_length;
 588 }
 589 
 590 uint
 591 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 592                                                      uint base_min_length,
 593                                                      uint desired_min_length,
 594                                                      uint desired_max_length) const {
 595   assert(adaptive_young_list_length(), "pre-condition");
 596   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 597 
 598   // In case some edge-condition makes the desired max length too small...
 599   if (desired_max_length <= desired_min_length) {
 600     return desired_min_length;
 601   }
 602 
 603   // We'll adjust min_young_length and max_young_length not to include
 604   // the already allocated young regions (i.e., so they reflect the
 605   // min and max eden regions we'll allocate). The base_min_length
 606   // will be reflected in the predictions by the
 607   // survivor_regions_evac_time prediction.
 608   assert(desired_min_length > base_min_length, "invariant");
 609   uint min_young_length = desired_min_length - base_min_length;
 610   assert(desired_max_length > base_min_length, "invariant");
 611   uint max_young_length = desired_max_length - base_min_length;
 612 
 613   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 614   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 615   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 616   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 617   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 618   double base_time_ms =
 619     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 620     survivor_regions_evac_time;
 621   uint available_free_regions = _free_regions_at_end_of_collection;
 622   uint base_free_regions = 0;
 623   if (available_free_regions > _reserve_regions) {
 624     base_free_regions = available_free_regions - _reserve_regions;
 625   }
 626 
 627   // Here, we will make sure that the shortest young length that
 628   // makes sense fits within the target pause time.
 629 
 630   if (predict_will_fit(min_young_length, base_time_ms,
 631                        base_free_regions, target_pause_time_ms)) {
 632     // The shortest young length will fit into the target pause time;
 633     // we'll now check whether the absolute maximum number of young
 634     // regions will fit in the target pause time. If not, we'll do
 635     // a binary search between min_young_length and max_young_length.
 636     if (predict_will_fit(max_young_length, base_time_ms,
 637                          base_free_regions, target_pause_time_ms)) {
 638       // The maximum young length will fit into the target pause time.
 639       // We are done so set min young length to the maximum length (as
 640       // the result is assumed to be returned in min_young_length).
 641       min_young_length = max_young_length;
 642     } else {
 643       // The maximum possible number of young regions will not fit within
 644       // the target pause time so we'll search for the optimal
 645       // length. The loop invariants are:
 646       //
 647       // min_young_length < max_young_length
 648       // min_young_length is known to fit into the target pause time
 649       // max_young_length is known not to fit into the target pause time
 650       //
 651       // Going into the loop we know the above hold as we've just
 652       // checked them. Every time around the loop we check whether
 653       // the middle value between min_young_length and
 654       // max_young_length fits into the target pause time. If it
 655       // does, it becomes the new min. If it doesn't, it becomes
 656       // the new max. This way we maintain the loop invariants.
 657 
 658       assert(min_young_length < max_young_length, "invariant");
 659       uint diff = (max_young_length - min_young_length) / 2;
 660       while (diff > 0) {
 661         uint young_length = min_young_length + diff;
 662         if (predict_will_fit(young_length, base_time_ms,
 663                              base_free_regions, target_pause_time_ms)) {
 664           min_young_length = young_length;
 665         } else {
 666           max_young_length = young_length;
 667         }
 668         assert(min_young_length <  max_young_length, "invariant");
 669         diff = (max_young_length - min_young_length) / 2;
 670       }
 671       // The results is min_young_length which, according to the
 672       // loop invariants, should fit within the target pause time.
 673 
 674       // These are the post-conditions of the binary search above:
 675       assert(min_young_length < max_young_length,
 676              "otherwise we should have discovered that max_young_length "
 677              "fits into the pause target and not done the binary search");
 678       assert(predict_will_fit(min_young_length, base_time_ms,
 679                               base_free_regions, target_pause_time_ms),
 680              "min_young_length, the result of the binary search, should "
 681              "fit into the pause target");
 682       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 683                                base_free_regions, target_pause_time_ms),
 684              "min_young_length, the result of the binary search, should be "
 685              "optimal, so no larger length should fit into the pause target");
 686     }
 687   } else {
 688     // Even the minimum length doesn't fit into the pause time
 689     // target, return it as the result nevertheless.
 690   }
 691   return base_min_length + min_young_length;
 692 }
 693 
 694 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
 695   double survivor_regions_evac_time = 0.0;
 696   for (HeapRegion * r = _recorded_survivor_head;
 697        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 698        r = r->get_next_young_region()) {
 699     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 700   }
 701   return survivor_regions_evac_time;
 702 }
 703 
 704 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 705   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 706 
 707   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 708   if (rs_lengths > _rs_lengths_prediction) {
 709     // add 10% to avoid having to recalculate often
 710     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 711     update_rs_lengths_prediction(rs_lengths_prediction);
 712 
 713     update_young_list_max_and_target_length(rs_lengths_prediction);
 714   }
 715 }
 716 
 717 void G1CollectorPolicy::update_rs_lengths_prediction() {
 718   update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
 719 }
 720 
 721 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
 722   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 723     _rs_lengths_prediction = prediction;
 724   }
 725 }
 726 
 727 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 728                                                bool is_tlab,
 729                                                bool* gc_overhead_limit_was_exceeded) {
 730   guarantee(false, "Not using this policy feature yet.");
 731   return NULL;
 732 }
 733 
 734 // This method controls how a collector handles one or more
 735 // of its generations being fully allocated.
 736 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 737                                                        bool is_tlab) {
 738   guarantee(false, "Not using this policy feature yet.");
 739   return NULL;
 740 }
 741 
 742 
 743 #ifndef PRODUCT
 744 bool G1CollectorPolicy::verify_young_ages() {
 745   HeapRegion* head = _g1->young_list()->first_region();
 746   return
 747     verify_young_ages(head, _short_lived_surv_rate_group);
 748   // also call verify_young_ages on any additional surv rate groups
 749 }
 750 
 751 bool
 752 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 753                                      SurvRateGroup *surv_rate_group) {
 754   guarantee( surv_rate_group != NULL, "pre-condition" );
 755 
 756   const char* name = surv_rate_group->name();
 757   bool ret = true;
 758   int prev_age = -1;
 759 
 760   for (HeapRegion* curr = head;
 761        curr != NULL;
 762        curr = curr->get_next_young_region()) {
 763     SurvRateGroup* group = curr->surv_rate_group();
 764     if (group == NULL && !curr->is_survivor()) {
 765       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
 766       ret = false;
 767     }
 768 
 769     if (surv_rate_group == group) {
 770       int age = curr->age_in_surv_rate_group();
 771 
 772       if (age < 0) {
 773         gclog_or_tty->print_cr("## %s: encountered negative age", name);
 774         ret = false;
 775       }
 776 
 777       if (age <= prev_age) {
 778         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
 779                                "(%d, %d)", name, age, prev_age);
 780         ret = false;
 781       }
 782       prev_age = age;
 783     }
 784   }
 785 
 786   return ret;
 787 }
 788 #endif // PRODUCT
 789 
 790 void G1CollectorPolicy::record_full_collection_start() {
 791   _full_collection_start_sec = os::elapsedTime();
 792   record_heap_size_info_at_start(true /* full */);
 793   // Release the future to-space so that it is available for compaction into.
 794   collector_state()->set_full_collection(true);
 795 }
 796 
 797 void G1CollectorPolicy::record_full_collection_end() {
 798   // Consider this like a collection pause for the purposes of allocation
 799   // since last pause.
 800   double end_sec = os::elapsedTime();
 801   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 802   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 803 
 804   _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
 805 
 806   update_recent_gc_times(end_sec, full_gc_time_ms);
 807 
 808   collector_state()->set_full_collection(false);
 809 
 810   // "Nuke" the heuristics that control the young/mixed GC
 811   // transitions and make sure we start with young GCs after the Full GC.
 812   collector_state()->set_gcs_are_young(true);
 813   collector_state()->set_last_young_gc(false);
 814   collector_state()->set_initiate_conc_mark_if_possible(false);
 815   collector_state()->set_during_initial_mark_pause(false);
 816   collector_state()->set_in_marking_window(false);
 817   collector_state()->set_in_marking_window_im(false);
 818 
 819   _short_lived_surv_rate_group->start_adding_regions();
 820   // also call this on any additional surv rate groups
 821 
 822   record_survivor_regions(0, NULL, NULL);
 823 
 824   _free_regions_at_end_of_collection = _g1->num_free_regions();
 825   // Reset survivors SurvRateGroup.
 826   _survivor_surv_rate_group->reset();
 827   update_young_list_max_and_target_length();
 828   update_rs_lengths_prediction();
 829   _collectionSetChooser->clear();
 830 }
 831 
 832 void G1CollectorPolicy::record_stop_world_start() {
 833   _stop_world_start = os::elapsedTime();
 834 }
 835 
 836 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
 837   // We only need to do this here as the policy will only be applied
 838   // to the GC we're about to start. so, no point is calculating this
 839   // every time we calculate / recalculate the target young length.
 840   update_survivors_policy();
 841 
 842   assert(_g1->used() == _g1->recalculate_used(),
 843          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 844          _g1->used(), _g1->recalculate_used());
 845 
 846   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 847   _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
 848   _stop_world_start = 0.0;
 849 
 850   record_heap_size_info_at_start(false /* full */);
 851 
 852   phase_times()->record_cur_collection_start_sec(start_time_sec);
 853   _pending_cards = _g1->pending_card_num();
 854 
 855   _collection_set_bytes_used_before = 0;
 856   _bytes_copied_during_gc = 0;
 857 
 858   collector_state()->set_last_gc_was_young(false);
 859 
 860   // do that for any other surv rate groups
 861   _short_lived_surv_rate_group->stop_adding_regions();
 862   _survivors_age_table.clear();
 863 
 864   assert( verify_young_ages(), "region age verification" );
 865 }
 866 
 867 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 868                                                    mark_init_elapsed_time_ms) {
 869   collector_state()->set_during_marking(true);
 870   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 871   collector_state()->set_during_initial_mark_pause(false);
 872   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 873 }
 874 
 875 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 876   _mark_remark_start_sec = os::elapsedTime();
 877   collector_state()->set_during_marking(false);
 878 }
 879 
 880 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 881   double end_time_sec = os::elapsedTime();
 882   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 883   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 884   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 885   _prev_collection_pause_end_ms += elapsed_time_ms;
 886 
 887   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec);
 888 }
 889 
 890 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 891   _mark_cleanup_start_sec = os::elapsedTime();
 892 }
 893 
 894 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 895   collector_state()->set_last_young_gc(true);
 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::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 934   if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
 935     return false;
 936   }
 937 
 938   size_t marking_initiating_used_threshold =
 939     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
 940   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 941   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 942 
 943   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
 944     if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
 945       ergo_verbose5(ErgoConcCycles,
 946         "request concurrent cycle initiation",
 947         ergo_format_reason("occupancy higher than threshold")
 948         ergo_format_byte("occupancy")
 949         ergo_format_byte("allocation request")
 950         ergo_format_byte_perc("threshold")
 951         ergo_format_str("source"),
 952         cur_used_bytes,
 953         alloc_byte_size,
 954         marking_initiating_used_threshold,
 955         (double) InitiatingHeapOccupancyPercent,
 956         source);
 957       return true;
 958     } else {
 959       ergo_verbose5(ErgoConcCycles,
 960         "do not request concurrent cycle initiation",
 961         ergo_format_reason("still doing mixed collections")
 962         ergo_format_byte("occupancy")
 963         ergo_format_byte("allocation request")
 964         ergo_format_byte_perc("threshold")
 965         ergo_format_str("source"),
 966         cur_used_bytes,
 967         alloc_byte_size,
 968         marking_initiating_used_threshold,
 969         (double) InitiatingHeapOccupancyPercent,
 970         source);
 971     }
 972   }
 973 
 974   return false;
 975 }
 976 
 977 // Anything below that is considered to be zero
 978 #define MIN_TIMER_GRANULARITY 0.0000001
 979 
 980 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
 981   double end_time_sec = os::elapsedTime();
 982   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
 983          "otherwise, the subtraction below does not make sense");
 984   size_t rs_size =
 985             _cur_collection_pause_used_regions_at_start - cset_region_length();
 986   size_t cur_used_bytes = _g1->used();
 987   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 988   bool last_pause_included_initial_mark = false;
 989   bool update_stats = !_g1->evacuation_failed();
 990 
 991 #ifndef PRODUCT
 992   if (G1YoungSurvRateVerbose) {
 993     gclog_or_tty->cr();
 994     _short_lived_surv_rate_group->print();
 995     // do that for any other surv rate groups too
 996   }
 997 #endif // PRODUCT
 998 
 999   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1000   if (last_pause_included_initial_mark) {
1001     record_concurrent_mark_init_end(0.0);
1002   } else if (need_to_start_conc_mark("end of GC")) {
1003     // Note: this might have already been set, if during the last
1004     // pause we decided to start a cycle but at the beginning of
1005     // this pause we decided to postpone it. That's OK.
1006     collector_state()->set_initiate_conc_mark_if_possible(true);
1007   }
1008 
1009   _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0, end_time_sec);
1010 
1011   if (update_stats) {
1012     _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1013     // this is where we update the allocation rate of the application
1014     double app_time_ms =
1015       (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1016     if (app_time_ms < MIN_TIMER_GRANULARITY) {
1017       // This usually happens due to the timer not having the required
1018       // granularity. Some Linuxes are the usual culprits.
1019       // We'll just set it to something (arbitrarily) small.
1020       app_time_ms = 1.0;
1021     }
1022     // We maintain the invariant that all objects allocated by mutator
1023     // threads will be allocated out of eden regions. So, we can use
1024     // the eden region number allocated since the previous GC to
1025     // calculate the application's allocate rate. The only exception
1026     // to that is humongous objects that are allocated separately. But
1027     // given that humongous object allocations do not really affect
1028     // either the pause's duration nor when the next pause will take
1029     // place we can safely ignore them here.
1030     uint regions_allocated = eden_cset_region_length();
1031     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1032     _alloc_rate_ms_seq->add(alloc_rate_ms);
1033 
1034     double interval_ms =
1035       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1036     update_recent_gc_times(end_time_sec, pause_time_ms);
1037     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1038     if (recent_avg_pause_time_ratio() < 0.0 ||
1039         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1040 #ifndef PRODUCT
1041       // Dump info to allow post-facto debugging
1042       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1043       gclog_or_tty->print_cr("-------------------------------------------");
1044       gclog_or_tty->print_cr("Recent GC Times (ms):");
1045       _recent_gc_times_ms->dump();
1046       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1047       _recent_prev_end_times_for_all_gcs_sec->dump();
1048       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1049                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1050       // In debug mode, terminate the JVM if the user wants to debug at this point.
1051       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1052 #endif  // !PRODUCT
1053       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1054       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1055       if (_recent_avg_pause_time_ratio < 0.0) {
1056         _recent_avg_pause_time_ratio = 0.0;
1057       } else {
1058         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1059         _recent_avg_pause_time_ratio = 1.0;
1060       }
1061     }
1062   }
1063 
1064   bool new_in_marking_window = collector_state()->in_marking_window();
1065   bool new_in_marking_window_im = false;
1066   if (last_pause_included_initial_mark) {
1067     new_in_marking_window = true;
1068     new_in_marking_window_im = true;
1069   }
1070 
1071   if (collector_state()->last_young_gc()) {
1072     // This is supposed to to be the "last young GC" before we start
1073     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1074 
1075     if (!last_pause_included_initial_mark) {
1076       if (next_gc_should_be_mixed("start mixed GCs",
1077                                   "do not start mixed GCs")) {
1078         collector_state()->set_gcs_are_young(false);
1079       }
1080     } else {
1081       ergo_verbose0(ErgoMixedGCs,
1082                     "do not start mixed GCs",
1083                     ergo_format_reason("concurrent cycle is about to start"));
1084     }
1085     collector_state()->set_last_young_gc(false);
1086   }
1087 
1088   if (!collector_state()->last_gc_was_young()) {
1089     // This is a mixed GC. Here we decide whether to continue doing
1090     // mixed GCs or not.
1091 
1092     if (!next_gc_should_be_mixed("continue mixed GCs",
1093                                  "do not continue mixed GCs")) {
1094       collector_state()->set_gcs_are_young(true);
1095     }
1096   }
1097 
1098   _short_lived_surv_rate_group->start_adding_regions();
1099   // Do that for any other surv rate groups
1100 
1101   if (update_stats) {
1102     double cost_per_card_ms = 0.0;
1103     double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1104     if (_pending_cards > 0) {
1105       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1106       _cost_per_card_ms_seq->add(cost_per_card_ms);
1107     }
1108     _cost_scan_hcc_seq->add(cost_scan_hcc);
1109 
1110     double cost_per_entry_ms = 0.0;
1111     if (cards_scanned > 10) {
1112       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1113       if (collector_state()->last_gc_was_young()) {
1114         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1115       } else {
1116         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1117       }
1118     }
1119 
1120     if (_max_rs_lengths > 0) {
1121       double cards_per_entry_ratio =
1122         (double) cards_scanned / (double) _max_rs_lengths;
1123       if (collector_state()->last_gc_was_young()) {
1124         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1125       } else {
1126         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1127       }
1128     }
1129 
1130     // This is defensive. For a while _max_rs_lengths could get
1131     // smaller than _recorded_rs_lengths which was causing
1132     // rs_length_diff to get very large and mess up the RSet length
1133     // predictions. The reason was unsafe concurrent updates to the
1134     // _inc_cset_recorded_rs_lengths field which the code below guards
1135     // against (see CR 7118202). This bug has now been fixed (see CR
1136     // 7119027). However, I'm still worried that
1137     // _inc_cset_recorded_rs_lengths might still end up somewhat
1138     // inaccurate. The concurrent refinement thread calculates an
1139     // RSet's length concurrently with other CR threads updating it
1140     // which might cause it to calculate the length incorrectly (if,
1141     // say, it's in mid-coarsening). So I'll leave in the defensive
1142     // conditional below just in case.
1143     size_t rs_length_diff = 0;
1144     if (_max_rs_lengths > _recorded_rs_lengths) {
1145       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1146     }
1147     _rs_length_diff_seq->add((double) rs_length_diff);
1148 
1149     size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1150     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1151     double cost_per_byte_ms = 0.0;
1152 
1153     if (copied_bytes > 0) {
1154       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1155       if (collector_state()->in_marking_window()) {
1156         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1157       } else {
1158         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1159       }
1160     }
1161 
1162     if (young_cset_region_length() > 0) {
1163       _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1164                                                young_cset_region_length());
1165     }
1166 
1167     if (old_cset_region_length() > 0) {
1168       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1169                                                    old_cset_region_length());
1170     }
1171 
1172     _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1173 
1174     _pending_cards_seq->add((double) _pending_cards);
1175     _rs_lengths_seq->add((double) _max_rs_lengths);
1176   }
1177 
1178   collector_state()->set_in_marking_window(new_in_marking_window);
1179   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1180   _free_regions_at_end_of_collection = _g1->num_free_regions();
1181   update_young_list_max_and_target_length();
1182   update_rs_lengths_prediction();
1183 
1184   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1185   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1186 
1187   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1188 
1189   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1190     ergo_verbose2(ErgoTiming,
1191                   "adjust concurrent refinement thresholds",
1192                   ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1193                   ergo_format_ms("Update RS time goal")
1194                   ergo_format_ms("Scan HCC time"),
1195                   update_rs_time_goal_ms,
1196                   scan_hcc_time_ms);
1197 
1198     update_rs_time_goal_ms = 0;
1199   } else {
1200     update_rs_time_goal_ms -= scan_hcc_time_ms;
1201   }
1202   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1203                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1204                                update_rs_time_goal_ms);
1205 
1206   _collectionSetChooser->verify();
1207 }
1208 
1209 #define EXT_SIZE_FORMAT "%.1f%s"
1210 #define EXT_SIZE_PARAMS(bytes)                                  \
1211   byte_size_in_proper_unit((double)(bytes)),                    \
1212   proper_unit_for_byte_size((bytes))
1213 
1214 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1215   YoungList* young_list = _g1->young_list();
1216   _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1217   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1218   _heap_capacity_bytes_before_gc = _g1->capacity();
1219   _heap_used_bytes_before_gc = _g1->used();
1220   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1221 
1222   _eden_capacity_bytes_before_gc =
1223          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1224 
1225   if (full) {
1226     _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1227   }
1228 }
1229 
1230 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1231   size_t bytes_after = _g1->used();
1232   size_t capacity = _g1->capacity();
1233 
1234   gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1235       byte_size_in_proper_unit(bytes_before),
1236       proper_unit_for_byte_size(bytes_before),
1237       byte_size_in_proper_unit(bytes_after),
1238       proper_unit_for_byte_size(bytes_after),
1239       byte_size_in_proper_unit(capacity),
1240       proper_unit_for_byte_size(capacity));
1241 }
1242 
1243 void G1CollectorPolicy::print_heap_transition() const {
1244   print_heap_transition(_heap_used_bytes_before_gc);
1245 }
1246 
1247 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1248   YoungList* young_list = _g1->young_list();
1249 
1250   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1251   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1252   size_t heap_used_bytes_after_gc = _g1->used();
1253 
1254   size_t heap_capacity_bytes_after_gc = _g1->capacity();
1255   size_t eden_capacity_bytes_after_gc =
1256     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1257 
1258   gclog_or_tty->print(
1259     "   [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1260     "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1261     "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1262     EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1263     EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1264     EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1265     EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1266     EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1267     EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1268     EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1269     EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1270     EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1271     EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1272     EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1273 
1274   if (full) {
1275     MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1276   }
1277 
1278   gclog_or_tty->cr();
1279 }
1280 
1281 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1282   phase_times()->print(pause_time_sec);
1283 }
1284 
1285 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1286                                                      double update_rs_processed_buffers,
1287                                                      double goal_ms) {
1288   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1289   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1290 
1291   if (G1UseAdaptiveConcRefinement) {
1292     const int k_gy = 3, k_gr = 6;
1293     const double inc_k = 1.1, dec_k = 0.9;
1294 
1295     int g = cg1r->green_zone();
1296     if (update_rs_time > goal_ms) {
1297       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1298     } else {
1299       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1300         g = (int)MAX2(g * inc_k, g + 1.0);
1301       }
1302     }
1303     // Change the refinement threads params
1304     cg1r->set_green_zone(g);
1305     cg1r->set_yellow_zone(g * k_gy);
1306     cg1r->set_red_zone(g * k_gr);
1307     cg1r->reinitialize_threads();
1308 
1309     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1310     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1311                                     cg1r->yellow_zone());
1312     // Change the barrier params
1313     dcqs.set_process_completed_threshold(processing_threshold);
1314     dcqs.set_max_completed_queue(cg1r->red_zone());
1315   }
1316 
1317   int curr_queue_size = dcqs.completed_buffers_num();
1318   if (curr_queue_size >= cg1r->yellow_zone()) {
1319     dcqs.set_completed_queue_padding(curr_queue_size);
1320   } else {
1321     dcqs.set_completed_queue_padding(0);
1322   }
1323   dcqs.notify_if_necessary();
1324 }
1325 
1326 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1327   return (size_t) get_new_prediction(_rs_length_diff_seq);
1328 }
1329 
1330 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1331   return get_new_prediction(_alloc_rate_ms_seq);
1332 }
1333 
1334 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1335   return get_new_prediction(_cost_per_card_ms_seq);
1336 }
1337 
1338 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1339   return get_new_prediction(_cost_scan_hcc_seq);
1340 }
1341 
1342 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1343   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1344 }
1345 
1346 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1347   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1348 }
1349 
1350 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1351   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1352     return predict_young_cards_per_entry_ratio();
1353   } else {
1354     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1355   }
1356 }
1357 
1358 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1359   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1360 }
1361 
1362 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1363   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1364 }
1365 
1366 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1367   if (collector_state()->gcs_are_young()) {
1368     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1369   } else {
1370     return predict_mixed_rs_scan_time_ms(card_num);
1371   }
1372 }
1373 
1374 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1375   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1376     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1377   } else {
1378     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1379   }
1380 }
1381 
1382 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1383   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1384     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1385   } else {
1386     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1387   }
1388 }
1389 
1390 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1391   if (collector_state()->during_concurrent_mark()) {
1392     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1393   } else {
1394     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1395   }
1396 }
1397 
1398 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1399   return get_new_prediction(_constant_other_time_ms_seq);
1400 }
1401 
1402 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1403   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1404 }
1405 
1406 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1407   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1408 }
1409 
1410 double G1CollectorPolicy::predict_remark_time_ms() const {
1411   return get_new_prediction(_concurrent_mark_remark_times_ms);
1412 }
1413 
1414 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1415   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1416 }
1417 
1418 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1419   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1420   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1421   double pred = get_new_prediction(seq);
1422   if (pred > 1.0) {
1423     pred = 1.0;
1424   }
1425   return pred;
1426 }
1427 
1428 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1429   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1430 }
1431 
1432 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1433   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1434 }
1435 
1436 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1437                                                        size_t scanned_cards) const {
1438   return
1439     predict_rs_update_time_ms(pending_cards) +
1440     predict_rs_scan_time_ms(scanned_cards) +
1441     predict_constant_other_time_ms();
1442 }
1443 
1444 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1445   size_t rs_length = predict_rs_length_diff();
1446   size_t card_num;
1447   if (collector_state()->gcs_are_young()) {
1448     card_num = predict_young_card_num(rs_length);
1449   } else {
1450     card_num = predict_non_young_card_num(rs_length);
1451   }
1452   return predict_base_elapsed_time_ms(pending_cards, card_num);
1453 }
1454 
1455 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1456   size_t bytes_to_copy;
1457   if (hr->is_marked())
1458     bytes_to_copy = hr->max_live_bytes();
1459   else {
1460     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1461     int age = hr->age_in_surv_rate_group();
1462     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1463     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1464   }
1465   return bytes_to_copy;
1466 }
1467 
1468 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1469                                                          bool for_young_gc) const {
1470   size_t rs_length = hr->rem_set()->occupied();
1471   size_t card_num;
1472 
1473   // Predicting the number of cards is based on which type of GC
1474   // we're predicting for.
1475   if (for_young_gc) {
1476     card_num = predict_young_card_num(rs_length);
1477   } else {
1478     card_num = predict_non_young_card_num(rs_length);
1479   }
1480   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1481 
1482   double region_elapsed_time_ms =
1483     predict_rs_scan_time_ms(card_num) +
1484     predict_object_copy_time_ms(bytes_to_copy);
1485 
1486   // The prediction of the "other" time for this region is based
1487   // upon the region type and NOT the GC type.
1488   if (hr->is_young()) {
1489     region_elapsed_time_ms += predict_young_other_time_ms(1);
1490   } else {
1491     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1492   }
1493   return region_elapsed_time_ms;
1494 }
1495 
1496 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1497                                                  uint survivor_cset_region_length) {
1498   _eden_cset_region_length     = eden_cset_region_length;
1499   _survivor_cset_region_length = survivor_cset_region_length;
1500   _old_cset_region_length      = 0;
1501 }
1502 
1503 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1504   _recorded_rs_lengths = rs_lengths;
1505 }
1506 
1507 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1508                                                double elapsed_ms) {
1509   _recent_gc_times_ms->add(elapsed_ms);
1510   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1511   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1512 }
1513 
1514 size_t G1CollectorPolicy::expansion_amount() const {
1515   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1516   double threshold = _gc_overhead_perc;
1517   if (recent_gc_overhead > threshold) {
1518     // We will double the existing space, or take
1519     // G1ExpandByPercentOfAvailable % of the available expansion
1520     // space, whichever is smaller, bounded below by a minimum
1521     // expansion (unless that's all that's left.)
1522     const size_t min_expand_bytes = 1*M;
1523     size_t reserved_bytes = _g1->max_capacity();
1524     size_t committed_bytes = _g1->capacity();
1525     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1526     size_t expand_bytes;
1527     size_t expand_bytes_via_pct =
1528       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1529     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1530     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1531     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1532 
1533     ergo_verbose5(ErgoHeapSizing,
1534                   "attempt heap expansion",
1535                   ergo_format_reason("recent GC overhead higher than "
1536                                      "threshold after GC")
1537                   ergo_format_perc("recent GC overhead")
1538                   ergo_format_perc("threshold")
1539                   ergo_format_byte("uncommitted")
1540                   ergo_format_byte_perc("calculated expansion amount"),
1541                   recent_gc_overhead, threshold,
1542                   uncommitted_bytes,
1543                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1544 
1545     return expand_bytes;
1546   } else {
1547     return 0;
1548   }
1549 }
1550 
1551 void G1CollectorPolicy::print_tracing_info() const {
1552   _trace_young_gen_time_data.print();
1553   _trace_old_gen_time_data.print();
1554 }
1555 
1556 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1557 #ifndef PRODUCT
1558   _short_lived_surv_rate_group->print_surv_rate_summary();
1559   // add this call for any other surv rate groups
1560 #endif // PRODUCT
1561 }
1562 
1563 bool G1CollectorPolicy::is_young_list_full() const {
1564   uint young_list_length = _g1->young_list()->length();
1565   uint young_list_target_length = _young_list_target_length;
1566   return young_list_length >= young_list_target_length;
1567 }
1568 
1569 bool G1CollectorPolicy::can_expand_young_list() const {
1570   uint young_list_length = _g1->young_list()->length();
1571   uint young_list_max_length = _young_list_max_length;
1572   return young_list_length < young_list_max_length;
1573 }
1574 
1575 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1576   uint expansion_region_num = 0;
1577   if (GCLockerEdenExpansionPercent > 0) {
1578     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1579     double expansion_region_num_d = perc * (double) _young_list_target_length;
1580     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1581     // less than 1.0) we'll get 1.
1582     expansion_region_num = (uint) ceil(expansion_region_num_d);
1583   } else {
1584     assert(expansion_region_num == 0, "sanity");
1585   }
1586   _young_list_max_length = _young_list_target_length + expansion_region_num;
1587   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1588 }
1589 
1590 // Calculates survivor space parameters.
1591 void G1CollectorPolicy::update_survivors_policy() {
1592   double max_survivor_regions_d =
1593                  (double) _young_list_target_length / (double) SurvivorRatio;
1594   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1595   // smaller than 1.0) we'll get 1.
1596   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1597 
1598   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1599         HeapRegion::GrainWords * _max_survivor_regions, counters());
1600 }
1601 
1602 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1603                                                      GCCause::Cause gc_cause) {
1604   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1605   if (!during_cycle) {
1606     ergo_verbose1(ErgoConcCycles,
1607                   "request concurrent cycle initiation",
1608                   ergo_format_reason("requested by GC cause")
1609                   ergo_format_str("GC cause"),
1610                   GCCause::to_string(gc_cause));
1611     collector_state()->set_initiate_conc_mark_if_possible(true);
1612     return true;
1613   } else {
1614     ergo_verbose1(ErgoConcCycles,
1615                   "do not request concurrent cycle initiation",
1616                   ergo_format_reason("concurrent cycle already in progress")
1617                   ergo_format_str("GC cause"),
1618                   GCCause::to_string(gc_cause));
1619     return false;
1620   }
1621 }
1622 
1623 void
1624 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1625   // We are about to decide on whether this pause will be an
1626   // initial-mark pause.
1627 
1628   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1629   // will set it here if we have to. However, it should be cleared by
1630   // the end of the pause (it's only set for the duration of an
1631   // initial-mark pause).
1632   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1633 
1634   if (collector_state()->initiate_conc_mark_if_possible()) {
1635     // We had noticed on a previous pause that the heap occupancy has
1636     // gone over the initiating threshold and we should start a
1637     // concurrent marking cycle. So we might initiate one.
1638 
1639     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1640     if (!during_cycle) {
1641       // The concurrent marking thread is not "during a cycle", i.e.,
1642       // it has completed the last one. So we can go ahead and
1643       // initiate a new cycle.
1644 
1645       collector_state()->set_during_initial_mark_pause(true);
1646       // We do not allow mixed GCs during marking.
1647       if (!collector_state()->gcs_are_young()) {
1648         collector_state()->set_gcs_are_young(true);
1649         ergo_verbose0(ErgoMixedGCs,
1650                       "end mixed GCs",
1651                       ergo_format_reason("concurrent cycle is about to start"));
1652       }
1653 
1654       // And we can now clear initiate_conc_mark_if_possible() as
1655       // we've already acted on it.
1656       collector_state()->set_initiate_conc_mark_if_possible(false);
1657 
1658       ergo_verbose0(ErgoConcCycles,
1659                   "initiate concurrent cycle",
1660                   ergo_format_reason("concurrent cycle initiation requested"));
1661     } else {
1662       // The concurrent marking thread is still finishing up the
1663       // previous cycle. If we start one right now the two cycles
1664       // overlap. In particular, the concurrent marking thread might
1665       // be in the process of clearing the next marking bitmap (which
1666       // we will use for the next cycle if we start one). Starting a
1667       // cycle now will be bad given that parts of the marking
1668       // information might get cleared by the marking thread. And we
1669       // cannot wait for the marking thread to finish the cycle as it
1670       // periodically yields while clearing the next marking bitmap
1671       // and, if it's in a yield point, it's waiting for us to
1672       // finish. So, at this point we will not start a cycle and we'll
1673       // let the concurrent marking thread complete the last one.
1674       ergo_verbose0(ErgoConcCycles,
1675                     "do not initiate concurrent cycle",
1676                     ergo_format_reason("concurrent cycle already in progress"));
1677     }
1678   }
1679 }
1680 
1681 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1682   G1CollectedHeap* _g1h;
1683   CSetChooserParUpdater _cset_updater;
1684 
1685 public:
1686   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1687                            uint chunk_size) :
1688     _g1h(G1CollectedHeap::heap()),
1689     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1690 
1691   bool doHeapRegion(HeapRegion* r) {
1692     // Do we have any marking information for this region?
1693     if (r->is_marked()) {
1694       // We will skip any region that's currently used as an old GC
1695       // alloc region (we should not consider those for collection
1696       // before we fill them up).
1697       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1698         _cset_updater.add_region(r);
1699       }
1700     }
1701     return false;
1702   }
1703 };
1704 
1705 class ParKnownGarbageTask: public AbstractGangTask {
1706   CollectionSetChooser* _hrSorted;
1707   uint _chunk_size;
1708   G1CollectedHeap* _g1;
1709   HeapRegionClaimer _hrclaimer;
1710 
1711 public:
1712   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1713       AbstractGangTask("ParKnownGarbageTask"),
1714       _hrSorted(hrSorted), _chunk_size(chunk_size),
1715       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1716 
1717   void work(uint worker_id) {
1718     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1719     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1720   }
1721 };
1722 
1723 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1724   assert(n_workers > 0, "Active gc workers should be greater than 0");
1725   const uint overpartition_factor = 4;
1726   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1727   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1728 }
1729 
1730 void
1731 G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1732   _collectionSetChooser->clear();
1733 
1734   WorkGang* workers = _g1->workers();
1735   uint n_workers = workers->active_workers();
1736 
1737   uint n_regions = _g1->num_regions();
1738   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1739   _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1740   ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1741   workers->run_task(&par_known_garbage_task);
1742 
1743   _collectionSetChooser->sort_regions();
1744 
1745   double end_sec = os::elapsedTime();
1746   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1747   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1748   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1749   _prev_collection_pause_end_ms += elapsed_time_ms;
1750   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec);
1751 }
1752 
1753 // Add the heap region at the head of the non-incremental collection set
1754 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1755   assert(_inc_cset_build_state == Active, "Precondition");
1756   assert(hr->is_old(), "the region should be old");
1757 
1758   assert(!hr->in_collection_set(), "should not already be in the CSet");
1759   _g1->register_old_region_with_cset(hr);
1760   hr->set_next_in_collection_set(_collection_set);
1761   _collection_set = hr;
1762   _collection_set_bytes_used_before += hr->used();
1763   size_t rs_length = hr->rem_set()->occupied();
1764   _recorded_rs_lengths += rs_length;
1765   _old_cset_region_length += 1;
1766 }
1767 
1768 // Initialize the per-collection-set information
1769 void G1CollectorPolicy::start_incremental_cset_building() {
1770   assert(_inc_cset_build_state == Inactive, "Precondition");
1771 
1772   _inc_cset_head = NULL;
1773   _inc_cset_tail = NULL;
1774   _inc_cset_bytes_used_before = 0;
1775 
1776   _inc_cset_max_finger = 0;
1777   _inc_cset_recorded_rs_lengths = 0;
1778   _inc_cset_recorded_rs_lengths_diffs = 0;
1779   _inc_cset_predicted_elapsed_time_ms = 0.0;
1780   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1781   _inc_cset_build_state = Active;
1782 }
1783 
1784 void G1CollectorPolicy::finalize_incremental_cset_building() {
1785   assert(_inc_cset_build_state == Active, "Precondition");
1786   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1787 
1788   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1789   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1790   // that adds a new region to the CSet. Further updates by the
1791   // concurrent refinement thread that samples the young RSet lengths
1792   // are accumulated in the *_diffs fields. Here we add the diffs to
1793   // the "main" fields.
1794 
1795   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1796     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1797   } else {
1798     // This is defensive. The diff should in theory be always positive
1799     // as RSets can only grow between GCs. However, given that we
1800     // sample their size concurrently with other threads updating them
1801     // it's possible that we might get the wrong size back, which
1802     // could make the calculations somewhat inaccurate.
1803     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1804     if (_inc_cset_recorded_rs_lengths >= diffs) {
1805       _inc_cset_recorded_rs_lengths -= diffs;
1806     } else {
1807       _inc_cset_recorded_rs_lengths = 0;
1808     }
1809   }
1810   _inc_cset_predicted_elapsed_time_ms +=
1811                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1812 
1813   _inc_cset_recorded_rs_lengths_diffs = 0;
1814   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1815 }
1816 
1817 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1818   // This routine is used when:
1819   // * adding survivor regions to the incremental cset at the end of an
1820   //   evacuation pause,
1821   // * adding the current allocation region to the incremental cset
1822   //   when it is retired, and
1823   // * updating existing policy information for a region in the
1824   //   incremental cset via young list RSet sampling.
1825   // Therefore this routine may be called at a safepoint by the
1826   // VM thread, or in-between safepoints by mutator threads (when
1827   // retiring the current allocation region) or a concurrent
1828   // refine thread (RSet sampling).
1829 
1830   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1831   size_t used_bytes = hr->used();
1832   _inc_cset_recorded_rs_lengths += rs_length;
1833   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1834   _inc_cset_bytes_used_before += used_bytes;
1835 
1836   // Cache the values we have added to the aggregated information
1837   // in the heap region in case we have to remove this region from
1838   // the incremental collection set, or it is updated by the
1839   // rset sampling code
1840   hr->set_recorded_rs_length(rs_length);
1841   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1842 }
1843 
1844 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1845                                                      size_t new_rs_length) {
1846   // Update the CSet information that is dependent on the new RS length
1847   assert(hr->is_young(), "Precondition");
1848   assert(!SafepointSynchronize::is_at_safepoint(),
1849                                                "should not be at a safepoint");
1850 
1851   // We could have updated _inc_cset_recorded_rs_lengths and
1852   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1853   // that atomically, as this code is executed by a concurrent
1854   // refinement thread, potentially concurrently with a mutator thread
1855   // allocating a new region and also updating the same fields. To
1856   // avoid the atomic operations we accumulate these updates on two
1857   // separate fields (*_diffs) and we'll just add them to the "main"
1858   // fields at the start of a GC.
1859 
1860   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1861   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1862   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1863 
1864   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1865   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1866   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1867   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1868 
1869   hr->set_recorded_rs_length(new_rs_length);
1870   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1871 }
1872 
1873 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1874   assert(hr->is_young(), "invariant");
1875   assert(hr->young_index_in_cset() > -1, "should have already been set");
1876   assert(_inc_cset_build_state == Active, "Precondition");
1877 
1878   // We need to clear and set the cached recorded/cached collection set
1879   // information in the heap region here (before the region gets added
1880   // to the collection set). An individual heap region's cached values
1881   // are calculated, aggregated with the policy collection set info,
1882   // and cached in the heap region here (initially) and (subsequently)
1883   // by the Young List sampling code.
1884 
1885   size_t rs_length = hr->rem_set()->occupied();
1886   add_to_incremental_cset_info(hr, rs_length);
1887 
1888   HeapWord* hr_end = hr->end();
1889   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1890 
1891   assert(!hr->in_collection_set(), "invariant");
1892   _g1->register_young_region_with_cset(hr);
1893   assert(hr->next_in_collection_set() == NULL, "invariant");
1894 }
1895 
1896 // Add the region at the RHS of the incremental cset
1897 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1898   // We should only ever be appending survivors at the end of a pause
1899   assert(hr->is_survivor(), "Logic");
1900 
1901   // Do the 'common' stuff
1902   add_region_to_incremental_cset_common(hr);
1903 
1904   // Now add the region at the right hand side
1905   if (_inc_cset_tail == NULL) {
1906     assert(_inc_cset_head == NULL, "invariant");
1907     _inc_cset_head = hr;
1908   } else {
1909     _inc_cset_tail->set_next_in_collection_set(hr);
1910   }
1911   _inc_cset_tail = hr;
1912 }
1913 
1914 // Add the region to the LHS of the incremental cset
1915 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1916   // Survivors should be added to the RHS at the end of a pause
1917   assert(hr->is_eden(), "Logic");
1918 
1919   // Do the 'common' stuff
1920   add_region_to_incremental_cset_common(hr);
1921 
1922   // Add the region at the left hand side
1923   hr->set_next_in_collection_set(_inc_cset_head);
1924   if (_inc_cset_head == NULL) {
1925     assert(_inc_cset_tail == NULL, "Invariant");
1926     _inc_cset_tail = hr;
1927   }
1928   _inc_cset_head = hr;
1929 }
1930 
1931 #ifndef PRODUCT
1932 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1933   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1934 
1935   st->print_cr("\nCollection_set:");
1936   HeapRegion* csr = list_head;
1937   while (csr != NULL) {
1938     HeapRegion* next = csr->next_in_collection_set();
1939     assert(csr->in_collection_set(), "bad CS");
1940     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
1941                  HR_FORMAT_PARAMS(csr),
1942                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
1943                  csr->age_in_surv_rate_group_cond());
1944     csr = next;
1945   }
1946 }
1947 #endif // !PRODUCT
1948 
1949 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
1950   // Returns the given amount of reclaimable bytes (that represents
1951   // the amount of reclaimable space still to be collected) as a
1952   // percentage of the current heap capacity.
1953   size_t capacity_bytes = _g1->capacity();
1954   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1955 }
1956 
1957 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1958                                                 const char* false_action_str) const {
1959   CollectionSetChooser* cset_chooser = _collectionSetChooser;
1960   if (cset_chooser->is_empty()) {
1961     ergo_verbose0(ErgoMixedGCs,
1962                   false_action_str,
1963                   ergo_format_reason("candidate old regions not available"));
1964     return false;
1965   }
1966 
1967   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1968   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1969   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1970   double threshold = (double) G1HeapWastePercent;
1971   if (reclaimable_perc <= threshold) {
1972     ergo_verbose4(ErgoMixedGCs,
1973               false_action_str,
1974               ergo_format_reason("reclaimable percentage not over threshold")
1975               ergo_format_region("candidate old regions")
1976               ergo_format_byte_perc("reclaimable")
1977               ergo_format_perc("threshold"),
1978               cset_chooser->remaining_regions(),
1979               reclaimable_bytes,
1980               reclaimable_perc, threshold);
1981     return false;
1982   }
1983 
1984   ergo_verbose4(ErgoMixedGCs,
1985                 true_action_str,
1986                 ergo_format_reason("candidate old regions available")
1987                 ergo_format_region("candidate old regions")
1988                 ergo_format_byte_perc("reclaimable")
1989                 ergo_format_perc("threshold"),
1990                 cset_chooser->remaining_regions(),
1991                 reclaimable_bytes,
1992                 reclaimable_perc, threshold);
1993   return true;
1994 }
1995 
1996 uint G1CollectorPolicy::calc_min_old_cset_length() const {
1997   // The min old CSet region bound is based on the maximum desired
1998   // number of mixed GCs after a cycle. I.e., even if some old regions
1999   // look expensive, we should add them to the CSet anyway to make
2000   // sure we go through the available old regions in no more than the
2001   // maximum desired number of mixed GCs.
2002   //
2003   // The calculation is based on the number of marked regions we added
2004   // to the CSet chooser in the first place, not how many remain, so
2005   // that the result is the same during all mixed GCs that follow a cycle.
2006 
2007   const size_t region_num = (size_t) _collectionSetChooser->length();
2008   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2009   size_t result = region_num / gc_num;
2010   // emulate ceiling
2011   if (result * gc_num < region_num) {
2012     result += 1;
2013   }
2014   return (uint) result;
2015 }
2016 
2017 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2018   // The max old CSet region bound is based on the threshold expressed
2019   // as a percentage of the heap size. I.e., it should bound the
2020   // number of old regions added to the CSet irrespective of how many
2021   // of them are available.
2022 
2023   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2024   const size_t region_num = g1h->num_regions();
2025   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2026   size_t result = region_num * perc / 100;
2027   // emulate ceiling
2028   if (100 * result < region_num * perc) {
2029     result += 1;
2030   }
2031   return (uint) result;
2032 }
2033 
2034 
2035 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2036   double young_start_time_sec = os::elapsedTime();
2037 
2038   YoungList* young_list = _g1->young_list();
2039   finalize_incremental_cset_building();
2040 
2041   guarantee(target_pause_time_ms > 0.0,
2042             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2043   guarantee(_collection_set == NULL, "Precondition");
2044 
2045   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2046   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2047 
2048   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2049                 "start choosing CSet",
2050                 ergo_format_size("_pending_cards")
2051                 ergo_format_ms("predicted base time")
2052                 ergo_format_ms("remaining time")
2053                 ergo_format_ms("target pause time"),
2054                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2055 
2056   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2057 
2058   if (collector_state()->last_gc_was_young()) {
2059     _trace_young_gen_time_data.increment_young_collection_count();
2060   } else {
2061     _trace_young_gen_time_data.increment_mixed_collection_count();
2062   }
2063 
2064   // The young list is laid with the survivor regions from the previous
2065   // pause are appended to the RHS of the young list, i.e.
2066   //   [Newly Young Regions ++ Survivors from last pause].
2067 
2068   uint survivor_region_length = young_list->survivor_length();
2069   uint eden_region_length = young_list->eden_length();
2070   init_cset_region_lengths(eden_region_length, survivor_region_length);
2071 
2072   HeapRegion* hr = young_list->first_survivor_region();
2073   while (hr != NULL) {
2074     assert(hr->is_survivor(), "badly formed young list");
2075     // There is a convention that all the young regions in the CSet
2076     // are tagged as "eden", so we do this for the survivors here. We
2077     // use the special set_eden_pre_gc() as it doesn't check that the
2078     // region is free (which is not the case here).
2079     hr->set_eden_pre_gc();
2080     hr = hr->get_next_young_region();
2081   }
2082 
2083   // Clear the fields that point to the survivor list - they are all young now.
2084   young_list->clear_survivors();
2085 
2086   _collection_set = _inc_cset_head;
2087   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2088   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2089 
2090   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2091                 "add young regions to CSet",
2092                 ergo_format_region("eden")
2093                 ergo_format_region("survivors")
2094                 ergo_format_ms("predicted young region time")
2095                 ergo_format_ms("target pause time"),
2096                 eden_region_length, survivor_region_length,
2097                 _inc_cset_predicted_elapsed_time_ms,
2098                 target_pause_time_ms);
2099 
2100   // The number of recorded young regions is the incremental
2101   // collection set's current size
2102   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2103 
2104   double young_end_time_sec = os::elapsedTime();
2105   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2106 
2107   return time_remaining_ms;
2108 }
2109 
2110 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2111   double non_young_start_time_sec = os::elapsedTime();
2112   double predicted_old_time_ms = 0.0;
2113 
2114 
2115   if (!collector_state()->gcs_are_young()) {
2116     CollectionSetChooser* cset_chooser = _collectionSetChooser;
2117     cset_chooser->verify();
2118     const uint min_old_cset_length = calc_min_old_cset_length();
2119     const uint max_old_cset_length = calc_max_old_cset_length();
2120 
2121     uint expensive_region_num = 0;
2122     bool check_time_remaining = adaptive_young_list_length();
2123 
2124     HeapRegion* hr = cset_chooser->peek();
2125     while (hr != NULL) {
2126       if (old_cset_region_length() >= max_old_cset_length) {
2127         // Added maximum number of old regions to the CSet.
2128         ergo_verbose2(ErgoCSetConstruction,
2129                       "finish adding old regions to CSet",
2130                       ergo_format_reason("old CSet region num reached max")
2131                       ergo_format_region("old")
2132                       ergo_format_region("max"),
2133                       old_cset_region_length(), max_old_cset_length);
2134         break;
2135       }
2136 
2137 
2138       // Stop adding regions if the remaining reclaimable space is
2139       // not above G1HeapWastePercent.
2140       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2141       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2142       double threshold = (double) G1HeapWastePercent;
2143       if (reclaimable_perc <= threshold) {
2144         // We've added enough old regions that the amount of uncollected
2145         // reclaimable space is at or below the waste threshold. Stop
2146         // adding old regions to the CSet.
2147         ergo_verbose5(ErgoCSetConstruction,
2148                       "finish adding old regions to CSet",
2149                       ergo_format_reason("reclaimable percentage not over threshold")
2150                       ergo_format_region("old")
2151                       ergo_format_region("max")
2152                       ergo_format_byte_perc("reclaimable")
2153                       ergo_format_perc("threshold"),
2154                       old_cset_region_length(),
2155                       max_old_cset_length,
2156                       reclaimable_bytes,
2157                       reclaimable_perc, threshold);
2158         break;
2159       }
2160 
2161       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2162       if (check_time_remaining) {
2163         if (predicted_time_ms > time_remaining_ms) {
2164           // Too expensive for the current CSet.
2165 
2166           if (old_cset_region_length() >= min_old_cset_length) {
2167             // We have added the minimum number of old regions to the CSet,
2168             // we are done with this CSet.
2169             ergo_verbose4(ErgoCSetConstruction,
2170                           "finish adding old regions to CSet",
2171                           ergo_format_reason("predicted time is too high")
2172                           ergo_format_ms("predicted time")
2173                           ergo_format_ms("remaining time")
2174                           ergo_format_region("old")
2175                           ergo_format_region("min"),
2176                           predicted_time_ms, time_remaining_ms,
2177                           old_cset_region_length(), min_old_cset_length);
2178             break;
2179           }
2180 
2181           // We'll add it anyway given that we haven't reached the
2182           // minimum number of old regions.
2183           expensive_region_num += 1;
2184         }
2185       } else {
2186         if (old_cset_region_length() >= min_old_cset_length) {
2187           // In the non-auto-tuning case, we'll finish adding regions
2188           // to the CSet if we reach the minimum.
2189           ergo_verbose2(ErgoCSetConstruction,
2190                         "finish adding old regions to CSet",
2191                         ergo_format_reason("old CSet region num reached min")
2192                         ergo_format_region("old")
2193                         ergo_format_region("min"),
2194                         old_cset_region_length(), min_old_cset_length);
2195           break;
2196         }
2197       }
2198 
2199       // We will add this region to the CSet.
2200       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2201       predicted_old_time_ms += predicted_time_ms;
2202       cset_chooser->pop(); // already have region via peek()
2203       _g1->old_set_remove(hr);
2204       add_old_region_to_cset(hr);
2205 
2206       hr = cset_chooser->peek();
2207     }
2208     if (hr == NULL) {
2209       ergo_verbose0(ErgoCSetConstruction,
2210                     "finish adding old regions to CSet",
2211                     ergo_format_reason("candidate old regions not available"));
2212     }
2213 
2214     if (expensive_region_num > 0) {
2215       // We print the information once here at the end, predicated on
2216       // whether we added any apparently expensive regions or not, to
2217       // avoid generating output per region.
2218       ergo_verbose4(ErgoCSetConstruction,
2219                     "added expensive regions to CSet",
2220                     ergo_format_reason("old CSet region num not reached min")
2221                     ergo_format_region("old")
2222                     ergo_format_region("expensive")
2223                     ergo_format_region("min")
2224                     ergo_format_ms("remaining time"),
2225                     old_cset_region_length(),
2226                     expensive_region_num,
2227                     min_old_cset_length,
2228                     time_remaining_ms);
2229     }
2230 
2231     cset_chooser->verify();
2232   }
2233 
2234   stop_incremental_cset_building();
2235 
2236   ergo_verbose3(ErgoCSetConstruction,
2237                 "finish choosing CSet",
2238                 ergo_format_region("old")
2239                 ergo_format_ms("predicted old region time")
2240                 ergo_format_ms("time remaining"),
2241                 old_cset_region_length(),
2242                 predicted_old_time_ms, time_remaining_ms);
2243 
2244   double non_young_end_time_sec = os::elapsedTime();
2245   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2246 }
2247 
2248 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2249   if(TraceYoungGenTime) {
2250     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2251   }
2252 }
2253 
2254 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2255   if(TraceYoungGenTime) {
2256     _all_yield_times_ms.add(yield_time_ms);
2257   }
2258 }
2259 
2260 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2261   if(TraceYoungGenTime) {
2262     _total.add(pause_time_ms);
2263     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2264     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2265     _parallel.add(phase_times->cur_collection_par_time_ms());
2266     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2267     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2268     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2269     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2270     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2271     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2272 
2273     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2274       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2275       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2276       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2277       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2278       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2279 
2280     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2281     _parallel_other.add(parallel_other_time);
2282     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2283   }
2284 }
2285 
2286 void TraceYoungGenTimeData::increment_young_collection_count() {
2287   if(TraceYoungGenTime) {
2288     ++_young_pause_num;
2289   }
2290 }
2291 
2292 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2293   if(TraceYoungGenTime) {
2294     ++_mixed_pause_num;
2295   }
2296 }
2297 
2298 void TraceYoungGenTimeData::print_summary(const char* str,
2299                                           const NumberSeq* seq) const {
2300   double sum = seq->sum();
2301   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2302                 str, sum / 1000.0, seq->avg());
2303 }
2304 
2305 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2306                                              const NumberSeq* seq) const {
2307   print_summary(str, seq);
2308   gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2309                 "(num", seq->num(), seq->sd(), seq->maximum());
2310 }
2311 
2312 void TraceYoungGenTimeData::print() const {
2313   if (!TraceYoungGenTime) {
2314     return;
2315   }
2316 
2317   gclog_or_tty->print_cr("ALL PAUSES");
2318   print_summary_sd("   Total", &_total);
2319   gclog_or_tty->cr();
2320   gclog_or_tty->cr();
2321   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2322   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2323   gclog_or_tty->cr();
2324 
2325   gclog_or_tty->print_cr("EVACUATION PAUSES");
2326 
2327   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2328     gclog_or_tty->print_cr("none");
2329   } else {
2330     print_summary_sd("   Evacuation Pauses", &_total);
2331     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2332     print_summary("      Parallel Time", &_parallel);
2333     print_summary("         Ext Root Scanning", &_ext_root_scan);
2334     print_summary("         SATB Filtering", &_satb_filtering);
2335     print_summary("         Update RS", &_update_rs);
2336     print_summary("         Scan RS", &_scan_rs);
2337     print_summary("         Object Copy", &_obj_copy);
2338     print_summary("         Termination", &_termination);
2339     print_summary("         Parallel Other", &_parallel_other);
2340     print_summary("      Clear CT", &_clear_ct);
2341     print_summary("      Other", &_other);
2342   }
2343   gclog_or_tty->cr();
2344 
2345   gclog_or_tty->print_cr("MISC");
2346   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2347   print_summary_sd("   Yields", &_all_yield_times_ms);
2348 }
2349 
2350 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2351   if (TraceOldGenTime) {
2352     _all_full_gc_times.add(full_gc_time_ms);
2353   }
2354 }
2355 
2356 void TraceOldGenTimeData::print() const {
2357   if (!TraceOldGenTime) {
2358     return;
2359   }
2360 
2361   if (_all_full_gc_times.num() > 0) {
2362     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2363       _all_full_gc_times.num(),
2364       _all_full_gc_times.sum() / 1000.0);
2365     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2366     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2367       _all_full_gc_times.sd(),
2368       _all_full_gc_times.maximum());
2369   }
2370 }