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/g1IHOPControl.hpp"
  32 #include "gc/g1/g1ErgoVerbose.hpp"
  33 #include "gc/g1/g1GCPhaseTimes.hpp"
  34 #include "gc/g1/g1Log.hpp"
  35 #include "gc/g1/heapRegion.inline.hpp"
  36 #include "gc/g1/heapRegionRemSet.hpp"
  37 #include "gc/shared/gcPolicyCounters.hpp"
  38 #include "runtime/arguments.hpp"
  39 #include "runtime/java.hpp"
  40 #include "runtime/mutexLocker.hpp"
  41 #include "utilities/debug.hpp"
  42 #include "utilities/pair.hpp"
  43 
  44 // Different defaults for different number of GC threads
  45 // They were chosen by running GCOld and SPECjbb on debris with different
  46 //   numbers of GC threads and choosing them based on the results
  47 
  48 // all the same
  49 static double rs_length_diff_defaults[] = {
  50   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
  51 };
  52 
  53 static double cost_per_card_ms_defaults[] = {
  54   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
  55 };
  56 
  57 // all the same
  58 static double young_cards_per_entry_ratio_defaults[] = {
  59   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
  60 };
  61 
  62 static double cost_per_entry_ms_defaults[] = {
  63   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
  64 };
  65 
  66 static double cost_per_byte_ms_defaults[] = {
  67   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
  68 };
  69 
  70 // these should be pretty consistent
  71 static double constant_other_time_ms_defaults[] = {
  72   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
  73 };
  74 
  75 
  76 static double young_other_cost_per_region_ms_defaults[] = {
  77   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
  78 };
  79 
  80 static double non_young_other_cost_per_region_ms_defaults[] = {
  81   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
  82 };
  83 
  84 G1CollectorPolicy::G1CollectorPolicy() :
  85   _predictor(G1ConfidencePercent / 100.0),
  86   _parallel_gc_threads(ParallelGCThreads),
  87 
  88   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  89   _stop_world_start(0.0),
  90 
  91   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  92   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  93 
  94   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _prev_collection_pause_end_ms(0.0),
  96   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 105   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 106   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 107   _non_young_other_cost_per_region_ms_seq(
 108                                          new TruncatedSeq(TruncatedSeqLength)),
 109 
 110   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 111   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 112 
 113   _pause_time_target_ms((double) MaxGCPauseMillis),
 114 
 115   _recent_prev_end_times_for_all_gcs_sec(
 116                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 117 
 118   _recent_avg_pause_time_ratio(0.0),
 119   _rs_lengths_prediction(0),
 120   _max_survivor_regions(0),
 121 
 122   _eden_used_bytes_before_gc(0),
 123   _survivor_used_bytes_before_gc(0),
 124   _heap_used_bytes_before_gc(0),
 125   _metaspace_used_bytes_before_gc(0),
 126   _eden_capacity_bytes_before_gc(0),
 127   _heap_capacity_bytes_before_gc(0),
 128 
 129   _eden_cset_region_length(0),
 130   _survivor_cset_region_length(0),
 131   _old_cset_region_length(0),
 132 
 133   _collection_set(NULL),
 134   _collection_set_bytes_used_before(0),
 135 
 136   // Incremental CSet attributes
 137   _inc_cset_build_state(Inactive),
 138   _inc_cset_head(NULL),
 139   _inc_cset_tail(NULL),
 140   _inc_cset_bytes_used_before(0),
 141   _inc_cset_max_finger(NULL),
 142   _inc_cset_recorded_rs_lengths(0),
 143   _inc_cset_recorded_rs_lengths_diffs(0),
 144   _inc_cset_predicted_elapsed_time_ms(0.0),
 145   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 146 
 147   // add here any more surv rate groups
 148   _recorded_survivor_regions(0),
 149   _recorded_survivor_head(NULL),
 150   _recorded_survivor_tail(NULL),
 151   _survivors_age_table(true),
 152 
 153   _gc_overhead_perc(0.0),
 154 
 155   _last_old_allocated_bytes(0),
 156   _ihop_control(NULL),
 157   _initial_mark_to_mixed() {
 158 
 159   // SurvRateGroups below must be initialized after the predictor because they
 160   // indirectly use it through this object passed to their constructor.
 161   _short_lived_surv_rate_group =
 162     new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
 163   _survivor_surv_rate_group =
 164     new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
 165 
 166   // Set up the region size and associated fields. Given that the
 167   // policy is created before the heap, we have to set this up here,
 168   // so it's done as soon as possible.
 169 
 170   // It would have been natural to pass initial_heap_byte_size() and
 171   // max_heap_byte_size() to setup_heap_region_size() but those have
 172   // not been set up at this point since they should be aligned with
 173   // the region size. So, there is a circular dependency here. We base
 174   // the region size on the heap size, but the heap size should be
 175   // aligned with the region size. To get around this we use the
 176   // unaligned values for the heap.
 177   HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
 178   HeapRegionRemSet::setup_remset_size();
 179 
 180   G1ErgoVerbose::initialize();
 181   if (PrintAdaptiveSizePolicy) {
 182     // Currently, we only use a single switch for all the heuristics.
 183     G1ErgoVerbose::set_enabled(true);
 184     // Given that we don't currently have a verboseness level
 185     // parameter, we'll hardcode this to high. This can be easily
 186     // changed in the future.
 187     G1ErgoVerbose::set_level(ErgoHigh);
 188   } else {
 189     G1ErgoVerbose::set_enabled(false);
 190   }
 191 
 192   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 193   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 194 
 195   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 196 
 197   int index = MIN2(_parallel_gc_threads - 1, 7);
 198 
 199   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 200   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 201   _cost_scan_hcc_seq->add(0.0);
 202   _young_cards_per_entry_ratio_seq->add(
 203                                   young_cards_per_entry_ratio_defaults[index]);
 204   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 205   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 206   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 207   _young_other_cost_per_region_ms_seq->add(
 208                                young_other_cost_per_region_ms_defaults[index]);
 209   _non_young_other_cost_per_region_ms_seq->add(
 210                            non_young_other_cost_per_region_ms_defaults[index]);
 211 
 212   // Below, we might need to calculate the pause time target based on
 213   // the pause interval. When we do so we are going to give G1 maximum
 214   // flexibility and allow it to do pauses when it needs to. So, we'll
 215   // arrange that the pause interval to be pause time target + 1 to
 216   // ensure that a) the pause time target is maximized with respect to
 217   // the pause interval and b) we maintain the invariant that pause
 218   // time target < pause interval. If the user does not want this
 219   // maximum flexibility, they will have to set the pause interval
 220   // explicitly.
 221 
 222   // First make sure that, if either parameter is set, its value is
 223   // reasonable.
 224   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 225     if (MaxGCPauseMillis < 1) {
 226       vm_exit_during_initialization("MaxGCPauseMillis should be "
 227                                     "greater than 0");
 228     }
 229   }
 230   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 231     if (GCPauseIntervalMillis < 1) {
 232       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 233                                     "greater than 0");
 234     }
 235   }
 236 
 237   // Then, if the pause time target parameter was not set, set it to
 238   // the default value.
 239   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 240     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 241       // The default pause time target in G1 is 200ms
 242       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 243     } else {
 244       // We do not allow the pause interval to be set without the
 245       // pause time target
 246       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 247                                     "without setting MaxGCPauseMillis");
 248     }
 249   }
 250 
 251   // Then, if the interval parameter was not set, set it according to
 252   // the pause time target (this will also deal with the case when the
 253   // pause time target is the default value).
 254   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 255     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 256   }
 257 
 258   // Finally, make sure that the two parameters are consistent.
 259   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 260     char buffer[256];
 261     jio_snprintf(buffer, 256,
 262                  "MaxGCPauseMillis (%u) should be less than "
 263                  "GCPauseIntervalMillis (%u)",
 264                  MaxGCPauseMillis, GCPauseIntervalMillis);
 265     vm_exit_during_initialization(buffer);
 266   }
 267 
 268   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 269   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 270   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 271 
 272   // start conservatively (around 50ms is about right)
 273   _concurrent_mark_remark_times_ms->add(0.05);
 274   _concurrent_mark_cleanup_times_ms->add(0.20);
 275   _tenuring_threshold = MaxTenuringThreshold;
 276 
 277   assert(GCTimeRatio > 0,
 278          "we should have set it to a default value set_g1_gc_flags() "
 279          "if a user set it to 0");
 280   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 281 
 282   uintx reserve_perc = G1ReservePercent;
 283   // Put an artificial ceiling on this so that it's not set to a silly value.
 284   if (reserve_perc > 50) {
 285     reserve_perc = 50;
 286     warning("G1ReservePercent is set to a value that is too large, "
 287             "it's been updated to " UINTX_FORMAT, reserve_perc);
 288   }
 289   _reserve_factor = (double) reserve_perc / 100.0;
 290   // This will be set when the heap is expanded
 291   // for the first time during initialization.
 292   _reserve_regions = 0;
 293 
 294   _collectionSetChooser = new CollectionSetChooser();
 295 }
 296 
 297 G1CollectorPolicy::~G1CollectorPolicy() {
 298   delete _ihop_control;
 299 }
 300 
 301 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
 302   return _predictor.get_new_prediction(seq);
 303 }
 304 
 305 void G1CollectorPolicy::initialize_alignments() {
 306   _space_alignment = HeapRegion::GrainBytes;
 307   size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
 308   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
 309   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 310 }
 311 
 312 void G1CollectorPolicy::initialize_flags() {
 313   if (G1HeapRegionSize != HeapRegion::GrainBytes) {
 314     FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
 315   }
 316 
 317   if (SurvivorRatio < 1) {
 318     vm_exit_during_initialization("Invalid survivor ratio specified");
 319   }
 320   CollectorPolicy::initialize_flags();
 321   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 322 }
 323 
 324 void G1CollectorPolicy::post_heap_initialize() {
 325   uintx max_regions = G1CollectedHeap::heap()->max_regions();
 326   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
 327   if (max_young_size != MaxNewSize) {
 328     FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
 329   }
 330 
 331   _ihop_control = create_ihop_control();
 332 }
 333 
 334 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
 335 
 336 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
 337         _min_desired_young_length(0), _max_desired_young_length(0) {
 338   if (FLAG_IS_CMDLINE(NewRatio)) {
 339     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 340       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 341     } else {
 342       _sizer_kind = SizerNewRatio;
 343       _adaptive_size = false;
 344       return;
 345     }
 346   }
 347 
 348   if (NewSize > MaxNewSize) {
 349     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 350       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 351               "A new max generation size of " SIZE_FORMAT "k will be used.",
 352               NewSize/K, MaxNewSize/K, NewSize/K);
 353     }
 354     MaxNewSize = NewSize;
 355   }
 356 
 357   if (FLAG_IS_CMDLINE(NewSize)) {
 358     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 359                                      1U);
 360     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 361       _max_desired_young_length =
 362                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 363                                   1U);
 364       _sizer_kind = SizerMaxAndNewSize;
 365       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 366     } else {
 367       _sizer_kind = SizerNewSizeOnly;
 368     }
 369   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 370     _max_desired_young_length =
 371                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 372                                   1U);
 373     _sizer_kind = SizerMaxNewSizeOnly;
 374   }
 375 }
 376 
 377 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 378   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 379   return MAX2(1U, default_value);
 380 }
 381 
 382 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 383   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 384   return MAX2(1U, default_value);
 385 }
 386 
 387 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
 388   assert(number_of_heap_regions > 0, "Heap must be initialized");
 389 
 390   switch (_sizer_kind) {
 391     case SizerDefaults:
 392       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 393       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 394       break;
 395     case SizerNewSizeOnly:
 396       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 397       *max_young_length = MAX2(*min_young_length, *max_young_length);
 398       break;
 399     case SizerMaxNewSizeOnly:
 400       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 401       *min_young_length = MIN2(*min_young_length, *max_young_length);
 402       break;
 403     case SizerMaxAndNewSize:
 404       // Do nothing. Values set on the command line, don't update them at runtime.
 405       break;
 406     case SizerNewRatio:
 407       *min_young_length = number_of_heap_regions / (NewRatio + 1);
 408       *max_young_length = *min_young_length;
 409       break;
 410     default:
 411       ShouldNotReachHere();
 412   }
 413 
 414   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
 415 }
 416 
 417 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
 418   // We need to pass the desired values because recalculation may not update these
 419   // values in some cases.
 420   uint temp = _min_desired_young_length;
 421   uint result = _max_desired_young_length;
 422   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
 423   return result;
 424 }
 425 
 426 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 427   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
 428           &_max_desired_young_length);
 429 }
 430 
 431 void G1CollectorPolicy::init() {
 432   // Set aside an initial future to_space.
 433   _g1 = G1CollectedHeap::heap();
 434 
 435   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 436 
 437   initialize_gc_policy_counters();
 438 
 439   if (adaptive_young_list_length()) {
 440     _young_list_fixed_length = 0;
 441   } else {
 442     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 443   }
 444   _free_regions_at_end_of_collection = _g1->num_free_regions();
 445 
 446   update_young_list_max_and_target_length();
 447   // We may immediately start allocating regions and placing them on the
 448   // collection set list. Initialize the per-collection set info
 449   start_incremental_cset_building();
 450 }
 451 
 452 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
 453   phase_times()->note_gc_start(num_active_workers);
 454 }
 455 
 456 // Create the jstat counters for the policy.
 457 void G1CollectorPolicy::initialize_gc_policy_counters() {
 458   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 459 }
 460 
 461 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 462                                          double base_time_ms,
 463                                          uint base_free_regions,
 464                                          double target_pause_time_ms) const {
 465   if (young_length >= base_free_regions) {
 466     // end condition 1: not enough space for the young regions
 467     return false;
 468   }
 469 
 470   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 471   size_t bytes_to_copy =
 472                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 473   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 474   double young_other_time_ms = predict_young_other_time_ms(young_length);
 475   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 476   if (pause_time_ms > target_pause_time_ms) {
 477     // end condition 2: prediction is over the target pause time
 478     return false;
 479   }
 480 
 481   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 482 
 483   // When copying, we will likely need more bytes free than is live in the region.
 484   // Add some safety margin to factor in the confidence of our guess, and the
 485   // natural expected waste.
 486   // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 487   // of the calculation: the lower the confidence, the more headroom.
 488   // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 489   // copying due to anticipated waste in the PLABs.
 490   double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 491   size_t expected_bytes_to_copy = safety_factor * bytes_to_copy;
 492 
 493   if (expected_bytes_to_copy > free_bytes) {
 494     // end condition 3: out-of-space
 495     return false;
 496   }
 497 
 498   // success!
 499   return true;
 500 }
 501 
 502 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 503   // re-calculate the necessary reserve
 504   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 505   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 506   // smaller than 1.0) we'll get 1.
 507   _reserve_regions = (uint) ceil(reserve_regions_d);
 508 
 509   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 510 }
 511 
 512 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 513                                                        uint base_min_length) const {
 514   uint desired_min_length = 0;
 515   if (adaptive_young_list_length()) {
 516     if (_alloc_rate_ms_seq->num() > 3) {
 517       double now_sec = os::elapsedTime();
 518       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 519       double alloc_rate_ms = predict_alloc_rate_ms();
 520       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 521     } else {
 522       // otherwise we don't have enough info to make the prediction
 523     }
 524   }
 525   desired_min_length += base_min_length;
 526   // make sure we don't go below any user-defined minimum bound
 527   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 528 }
 529 
 530 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
 531   // Here, we might want to also take into account any additional
 532   // constraints (i.e., user-defined minimum bound). Currently, we
 533   // effectively don't set this bound.
 534   return _young_gen_sizer->max_desired_young_length();
 535 }
 536 
 537 uint G1CollectorPolicy::update_young_list_max_and_target_length() {
 538   return update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq));
 539 }
 540 
 541 uint G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 542   uint unbounded_target_length = update_young_list_target_length(rs_lengths);
 543   update_max_gc_locker_expansion();
 544   return unbounded_target_length;
 545 }
 546 
 547 uint G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 548   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
 549   _young_list_target_length = young_lengths.first;
 550   return young_lengths.second;
 551 }
 552 
 553 G1CollectorPolicy::YoungTargetLengths G1CollectorPolicy::young_list_target_lengths(size_t rs_lengths) const {
 554   YoungTargetLengths result;
 555 
 556   // Calculate the absolute and desired min bounds first.
 557 
 558   // This is how many young regions we already have (currently: the survivors).
 559   uint base_min_length = recorded_survivor_regions();
 560   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 561   // This is the absolute minimum young length. Ensure that we
 562   // will at least have one eden region available for allocation.
 563   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 564   // If we shrank the young list target it should not shrink below the current size.
 565   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 566   // Calculate the absolute and desired max bounds.
 567 
 568   uint desired_max_length = calculate_young_list_desired_max_length();
 569 
 570   uint young_list_target_length = 0;
 571   if (adaptive_young_list_length()) {
 572     if (collector_state()->gcs_are_young()) {
 573       young_list_target_length =
 574                         calculate_young_list_target_length(rs_lengths,
 575                                                            base_min_length,
 576                                                            desired_min_length,
 577                                                            desired_max_length);
 578     } else {
 579       // Don't calculate anything and let the code below bound it to
 580       // the desired_min_length, i.e., do the next GC as soon as
 581       // possible to maximize how many old regions we can add to it.
 582     }
 583   } else {
 584     // The user asked for a fixed young gen so we'll fix the young gen
 585     // whether the next GC is young or mixed.
 586     young_list_target_length = _young_list_fixed_length;
 587   }
 588 
 589   result.second = young_list_target_length;
 590   
 591   // We will try our best not to "eat" into the reserve.
 592   uint absolute_max_length = 0;
 593   if (_free_regions_at_end_of_collection > _reserve_regions) {
 594     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 595   }
 596   if (desired_max_length > absolute_max_length) {
 597     desired_max_length = absolute_max_length;
 598   }
 599 
 600   // Make sure we don't go over the desired max length, nor under the
 601   // desired min length. In case they clash, desired_min_length wins
 602   // which is why that test is second.
 603   if (young_list_target_length > desired_max_length) {
 604     young_list_target_length = desired_max_length;
 605   }
 606   if (young_list_target_length < desired_min_length) {
 607     young_list_target_length = desired_min_length;
 608   }
 609 
 610   assert(young_list_target_length > recorded_survivor_regions(),
 611          "we should be able to allocate at least one eden region");
 612   assert(young_list_target_length >= absolute_min_length, "post-condition");
 613 
 614   result.first = young_list_target_length;
 615   return result;
 616 }
 617 
 618 uint
 619 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 620                                                      uint base_min_length,
 621                                                      uint desired_min_length,
 622                                                      uint desired_max_length) const {
 623   assert(adaptive_young_list_length(), "pre-condition");
 624   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 625 
 626   // In case some edge-condition makes the desired max length too small...
 627   if (desired_max_length <= desired_min_length) {
 628     return desired_min_length;
 629   }
 630 
 631   // We'll adjust min_young_length and max_young_length not to include
 632   // the already allocated young regions (i.e., so they reflect the
 633   // min and max eden regions we'll allocate). The base_min_length
 634   // will be reflected in the predictions by the
 635   // survivor_regions_evac_time prediction.
 636   assert(desired_min_length > base_min_length, "invariant");
 637   uint min_young_length = desired_min_length - base_min_length;
 638   assert(desired_max_length > base_min_length, "invariant");
 639   uint max_young_length = desired_max_length - base_min_length;
 640 
 641   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 642   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 643   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 644   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 645   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 646   double base_time_ms =
 647     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 648     survivor_regions_evac_time;
 649   uint available_free_regions = _free_regions_at_end_of_collection;
 650   uint base_free_regions = 0;
 651   if (available_free_regions > _reserve_regions) {
 652     base_free_regions = available_free_regions - _reserve_regions;
 653   }
 654 
 655   // Here, we will make sure that the shortest young length that
 656   // makes sense fits within the target pause time.
 657 
 658   if (predict_will_fit(min_young_length, base_time_ms,
 659                        base_free_regions, target_pause_time_ms)) {
 660     // The shortest young length will fit into the target pause time;
 661     // we'll now check whether the absolute maximum number of young
 662     // regions will fit in the target pause time. If not, we'll do
 663     // a binary search between min_young_length and max_young_length.
 664     if (predict_will_fit(max_young_length, base_time_ms,
 665                          base_free_regions, target_pause_time_ms)) {
 666       // The maximum young length will fit into the target pause time.
 667       // We are done so set min young length to the maximum length (as
 668       // the result is assumed to be returned in min_young_length).
 669       min_young_length = max_young_length;
 670     } else {
 671       // The maximum possible number of young regions will not fit within
 672       // the target pause time so we'll search for the optimal
 673       // length. The loop invariants are:
 674       //
 675       // min_young_length < max_young_length
 676       // min_young_length is known to fit into the target pause time
 677       // max_young_length is known not to fit into the target pause time
 678       //
 679       // Going into the loop we know the above hold as we've just
 680       // checked them. Every time around the loop we check whether
 681       // the middle value between min_young_length and
 682       // max_young_length fits into the target pause time. If it
 683       // does, it becomes the new min. If it doesn't, it becomes
 684       // the new max. This way we maintain the loop invariants.
 685 
 686       assert(min_young_length < max_young_length, "invariant");
 687       uint diff = (max_young_length - min_young_length) / 2;
 688       while (diff > 0) {
 689         uint young_length = min_young_length + diff;
 690         if (predict_will_fit(young_length, base_time_ms,
 691                              base_free_regions, target_pause_time_ms)) {
 692           min_young_length = young_length;
 693         } else {
 694           max_young_length = young_length;
 695         }
 696         assert(min_young_length <  max_young_length, "invariant");
 697         diff = (max_young_length - min_young_length) / 2;
 698       }
 699       // The results is min_young_length which, according to the
 700       // loop invariants, should fit within the target pause time.
 701 
 702       // These are the post-conditions of the binary search above:
 703       assert(min_young_length < max_young_length,
 704              "otherwise we should have discovered that max_young_length "
 705              "fits into the pause target and not done the binary search");
 706       assert(predict_will_fit(min_young_length, base_time_ms,
 707                               base_free_regions, target_pause_time_ms),
 708              "min_young_length, the result of the binary search, should "
 709              "fit into the pause target");
 710       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 711                                base_free_regions, target_pause_time_ms),
 712              "min_young_length, the result of the binary search, should be "
 713              "optimal, so no larger length should fit into the pause target");
 714     }
 715   } else {
 716     // Even the minimum length doesn't fit into the pause time
 717     // target, return it as the result nevertheless.
 718   }
 719   return base_min_length + min_young_length;
 720 }
 721 
 722 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
 723   double survivor_regions_evac_time = 0.0;
 724   for (HeapRegion * r = _recorded_survivor_head;
 725        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 726        r = r->get_next_young_region()) {
 727     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 728   }
 729   return survivor_regions_evac_time;
 730 }
 731 
 732 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 733   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 734 
 735   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 736   if (rs_lengths > _rs_lengths_prediction) {
 737     // add 10% to avoid having to recalculate often
 738     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 739     update_rs_lengths_prediction(rs_lengths_prediction);
 740 
 741     update_young_list_max_and_target_length(rs_lengths_prediction);
 742   }
 743 }
 744 
 745 void G1CollectorPolicy::update_rs_lengths_prediction() {
 746   update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
 747 }
 748 
 749 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
 750   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 751     _rs_lengths_prediction = prediction;
 752   }
 753 }
 754 
 755 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 756                                                bool is_tlab,
 757                                                bool* gc_overhead_limit_was_exceeded) {
 758   guarantee(false, "Not using this policy feature yet.");
 759   return NULL;
 760 }
 761 
 762 // This method controls how a collector handles one or more
 763 // of its generations being fully allocated.
 764 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 765                                                        bool is_tlab) {
 766   guarantee(false, "Not using this policy feature yet.");
 767   return NULL;
 768 }
 769 
 770 
 771 #ifndef PRODUCT
 772 bool G1CollectorPolicy::verify_young_ages() {
 773   HeapRegion* head = _g1->young_list()->first_region();
 774   return
 775     verify_young_ages(head, _short_lived_surv_rate_group);
 776   // also call verify_young_ages on any additional surv rate groups
 777 }
 778 
 779 bool
 780 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 781                                      SurvRateGroup *surv_rate_group) {
 782   guarantee( surv_rate_group != NULL, "pre-condition" );
 783 
 784   const char* name = surv_rate_group->name();
 785   bool ret = true;
 786   int prev_age = -1;
 787 
 788   for (HeapRegion* curr = head;
 789        curr != NULL;
 790        curr = curr->get_next_young_region()) {
 791     SurvRateGroup* group = curr->surv_rate_group();
 792     if (group == NULL && !curr->is_survivor()) {
 793       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
 794       ret = false;
 795     }
 796 
 797     if (surv_rate_group == group) {
 798       int age = curr->age_in_surv_rate_group();
 799 
 800       if (age < 0) {
 801         gclog_or_tty->print_cr("## %s: encountered negative age", name);
 802         ret = false;
 803       }
 804 
 805       if (age <= prev_age) {
 806         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
 807                                "(%d, %d)", name, age, prev_age);
 808         ret = false;
 809       }
 810       prev_age = age;
 811     }
 812   }
 813 
 814   return ret;
 815 }
 816 #endif // PRODUCT
 817 
 818 void G1CollectorPolicy::record_full_collection_start() {
 819   _full_collection_start_sec = os::elapsedTime();
 820   record_heap_size_info_at_start(true /* full */);
 821   // Release the future to-space so that it is available for compaction into.
 822   collector_state()->set_full_collection(true);
 823 }
 824 
 825 void G1CollectorPolicy::record_full_collection_end() {
 826   // Consider this like a collection pause for the purposes of allocation
 827   // since last pause.
 828   double end_sec = os::elapsedTime();
 829   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 830   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 831 
 832   _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
 833 
 834   update_recent_gc_times(end_sec, full_gc_time_ms);
 835 
 836   collector_state()->set_full_collection(false);
 837 
 838   // "Nuke" the heuristics that control the young/mixed GC
 839   // transitions and make sure we start with young GCs after the Full GC.
 840   collector_state()->set_gcs_are_young(true);
 841   collector_state()->set_last_young_gc(false);
 842   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 843   collector_state()->set_during_initial_mark_pause(false);
 844   collector_state()->set_in_marking_window(false);
 845   collector_state()->set_in_marking_window_im(false);
 846 
 847   _short_lived_surv_rate_group->start_adding_regions();
 848   // also call this on any additional surv rate groups
 849 
 850   record_survivor_regions(0, NULL, NULL);
 851 
 852   _free_regions_at_end_of_collection = _g1->num_free_regions();
 853   // Reset survivors SurvRateGroup.
 854   _survivor_surv_rate_group->reset();
 855   update_young_list_max_and_target_length();
 856   update_rs_lengths_prediction();
 857   _collectionSetChooser->clear();
 858 
 859   _last_old_allocated_bytes = 0;
 860 
 861   record_pause(FullGC, _full_collection_start_sec, end_sec);
 862 }
 863 
 864 void G1CollectorPolicy::record_stop_world_start() {
 865   _stop_world_start = os::elapsedTime();
 866 }
 867 
 868 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
 869   // We only need to do this here as the policy will only be applied
 870   // to the GC we're about to start. so, no point is calculating this
 871   // every time we calculate / recalculate the target young length.
 872   update_survivors_policy();
 873 
 874   assert(_g1->used() == _g1->recalculate_used(),
 875          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 876          _g1->used(), _g1->recalculate_used());
 877 
 878   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 879   _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
 880   _stop_world_start = 0.0;
 881 
 882   record_heap_size_info_at_start(false /* full */);
 883 
 884   phase_times()->record_cur_collection_start_sec(start_time_sec);
 885   _pending_cards = _g1->pending_card_num();
 886 
 887   _collection_set_bytes_used_before = 0;
 888   _bytes_copied_during_gc = 0;
 889 
 890   collector_state()->set_last_gc_was_young(false);
 891 
 892   // do that for any other surv rate groups
 893   _short_lived_surv_rate_group->stop_adding_regions();
 894   _survivors_age_table.clear();
 895 
 896   assert( verify_young_ages(), "region age verification" );
 897 }
 898 
 899 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 900                                                    mark_init_elapsed_time_ms) {
 901   collector_state()->set_during_marking(true);
 902   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 903   collector_state()->set_during_initial_mark_pause(false);
 904   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 905 }
 906 
 907 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 908   _mark_remark_start_sec = os::elapsedTime();
 909   collector_state()->set_during_marking(false);
 910 }
 911 
 912 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 913   double end_time_sec = os::elapsedTime();
 914   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 915   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 916   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 917   _prev_collection_pause_end_ms += elapsed_time_ms;
 918 
 919   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 920 }
 921 
 922 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 923   _mark_cleanup_start_sec = os::elapsedTime();
 924 }
 925 
 926 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 927   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 928                                                               "skip last young-only gc");
 929   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 930   // We skip the marking phase.
 931   if (!should_continue_with_reclaim) {
 932     abort_time_to_mixed_tracking();
 933   }
 934   collector_state()->set_in_marking_window(false);
 935 }
 936 
 937 void G1CollectorPolicy::record_concurrent_pause() {
 938   if (_stop_world_start > 0.0) {
 939     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 940     _trace_young_gen_time_data.record_yield_time(yield_ms);
 941   }
 942 }
 943 
 944 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 945   return phase_times()->average_time_ms(phase);
 946 }
 947 
 948 double G1CollectorPolicy::young_other_time_ms() const {
 949   return phase_times()->young_cset_choice_time_ms() +
 950          phase_times()->young_free_cset_time_ms();
 951 }
 952 
 953 double G1CollectorPolicy::non_young_other_time_ms() const {
 954   return phase_times()->non_young_cset_choice_time_ms() +
 955          phase_times()->non_young_free_cset_time_ms();
 956 
 957 }
 958 
 959 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
 960   return pause_time_ms -
 961          average_time_ms(G1GCPhaseTimes::UpdateRS) -
 962          average_time_ms(G1GCPhaseTimes::ScanRS) -
 963          average_time_ms(G1GCPhaseTimes::ObjCopy) -
 964          average_time_ms(G1GCPhaseTimes::Termination);
 965 }
 966 
 967 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
 968   return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
 969 }
 970 
 971 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
 972   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 973 }
 974 
 975 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 976   if (about_to_start_mixed_phase()) {
 977     return false;
 978   }
 979 
 980   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 981 
 982   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 983   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 984   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 985 
 986   if (marking_request_bytes > marking_initiating_used_threshold) {
 987     if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
 988       ergo_verbose5(ErgoConcCycles,
 989         "request concurrent cycle initiation",
 990         ergo_format_reason("occupancy higher than threshold")
 991         ergo_format_byte("occupancy")
 992         ergo_format_byte("allocation request")
 993         ergo_format_byte_perc("threshold")
 994         ergo_format_str("source"),
 995         cur_used_bytes,
 996         alloc_byte_size,
 997         marking_initiating_used_threshold,
 998         (double) marking_initiating_used_threshold / _g1->capacity() * 100,
 999         source);
1000       return true;
1001     } else {
1002       ergo_verbose5(ErgoConcCycles,
1003         "do not request concurrent cycle initiation",
1004         ergo_format_reason("still doing mixed collections")
1005         ergo_format_byte("occupancy")
1006         ergo_format_byte("allocation request")
1007         ergo_format_byte_perc("threshold")
1008         ergo_format_str("source"),
1009         cur_used_bytes,
1010         alloc_byte_size,
1011         marking_initiating_used_threshold,
1012         (double) InitiatingHeapOccupancyPercent,
1013         source);
1014     }
1015   }
1016 
1017   return false;
1018 }
1019 
1020 // Anything below that is considered to be zero
1021 #define MIN_TIMER_GRANULARITY 0.0000001
1022 
1023 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
1024   double end_time_sec = os::elapsedTime();
1025   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1026          "otherwise, the subtraction below does not make sense");
1027   size_t cur_used_bytes = _g1->used();
1028   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1029   bool last_pause_included_initial_mark = false;
1030   bool update_stats = !_g1->evacuation_failed();
1031 
1032 #ifndef PRODUCT
1033   if (G1YoungSurvRateVerbose) {
1034     gclog_or_tty->cr();
1035     _short_lived_surv_rate_group->print();
1036     // do that for any other surv rate groups too
1037   }
1038 #endif // PRODUCT
1039 
1040   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
1041 
1042   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1043   if (last_pause_included_initial_mark) {
1044     record_concurrent_mark_init_end(0.0);
1045   } else {
1046     maybe_start_marking();
1047   }
1048 
1049   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1050   if (app_time_ms < MIN_TIMER_GRANULARITY) {
1051     // This usually happens due to the timer not having the required
1052     // granularity. Some Linuxes are the usual culprits.
1053     // We'll just set it to something (arbitrarily) small.
1054     app_time_ms = 1.0;
1055   }
1056 
1057   if (update_stats) {
1058     _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1059     // We maintain the invariant that all objects allocated by mutator
1060     // threads will be allocated out of eden regions. So, we can use
1061     // the eden region number allocated since the previous GC to
1062     // calculate the application's allocate rate. The only exception
1063     // to that is humongous objects that are allocated separately. But
1064     // given that humongous object allocations do not really affect
1065     // either the pause's duration nor when the next pause will take
1066     // place we can safely ignore them here.
1067     uint regions_allocated = eden_cset_region_length();
1068     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1069     _alloc_rate_ms_seq->add(alloc_rate_ms);
1070 
1071     double interval_ms =
1072       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1073     update_recent_gc_times(end_time_sec, pause_time_ms);
1074     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1075     if (recent_avg_pause_time_ratio() < 0.0 ||
1076         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1077       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1078       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1079       if (_recent_avg_pause_time_ratio < 0.0) {
1080         _recent_avg_pause_time_ratio = 0.0;
1081       } else {
1082         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1083         _recent_avg_pause_time_ratio = 1.0;
1084       }
1085     }
1086   }
1087 
1088   bool new_in_marking_window = collector_state()->in_marking_window();
1089   bool new_in_marking_window_im = false;
1090   if (last_pause_included_initial_mark) {
1091     new_in_marking_window = true;
1092     new_in_marking_window_im = true;
1093   }
1094 
1095   if (collector_state()->last_young_gc()) {
1096     // This is supposed to to be the "last young GC" before we start
1097     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1098     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1099 
1100     if (next_gc_should_be_mixed("start mixed GCs",
1101                                 "do not start mixed GCs")) {
1102       collector_state()->set_gcs_are_young(false);
1103     } else {
1104       // We aborted the mixed GC phase early.
1105       abort_time_to_mixed_tracking();
1106     }
1107 
1108     collector_state()->set_last_young_gc(false);
1109   }
1110 
1111   if (!collector_state()->last_gc_was_young()) {
1112     // This is a mixed GC. Here we decide whether to continue doing
1113     // mixed GCs or not.
1114     if (!next_gc_should_be_mixed("continue mixed GCs",
1115                                  "do not continue mixed GCs")) {
1116       collector_state()->set_gcs_are_young(true);
1117 
1118       maybe_start_marking();
1119     }
1120   }
1121 
1122   _short_lived_surv_rate_group->start_adding_regions();
1123   // Do that for any other surv rate groups
1124 
1125   if (update_stats) {
1126     double cost_per_card_ms = 0.0;
1127     double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1128     if (_pending_cards > 0) {
1129       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1130       _cost_per_card_ms_seq->add(cost_per_card_ms);
1131     }
1132     _cost_scan_hcc_seq->add(cost_scan_hcc);
1133 
1134     double cost_per_entry_ms = 0.0;
1135     if (cards_scanned > 10) {
1136       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1137       if (collector_state()->last_gc_was_young()) {
1138         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1139       } else {
1140         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1141       }
1142     }
1143 
1144     if (_max_rs_lengths > 0) {
1145       double cards_per_entry_ratio =
1146         (double) cards_scanned / (double) _max_rs_lengths;
1147       if (collector_state()->last_gc_was_young()) {
1148         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1149       } else {
1150         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1151       }
1152     }
1153 
1154     // This is defensive. For a while _max_rs_lengths could get
1155     // smaller than _recorded_rs_lengths which was causing
1156     // rs_length_diff to get very large and mess up the RSet length
1157     // predictions. The reason was unsafe concurrent updates to the
1158     // _inc_cset_recorded_rs_lengths field which the code below guards
1159     // against (see CR 7118202). This bug has now been fixed (see CR
1160     // 7119027). However, I'm still worried that
1161     // _inc_cset_recorded_rs_lengths might still end up somewhat
1162     // inaccurate. The concurrent refinement thread calculates an
1163     // RSet's length concurrently with other CR threads updating it
1164     // which might cause it to calculate the length incorrectly (if,
1165     // say, it's in mid-coarsening). So I'll leave in the defensive
1166     // conditional below just in case.
1167     size_t rs_length_diff = 0;
1168     if (_max_rs_lengths > _recorded_rs_lengths) {
1169       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1170     }
1171     _rs_length_diff_seq->add((double) rs_length_diff);
1172 
1173     size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1174     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1175     double cost_per_byte_ms = 0.0;
1176 
1177     if (copied_bytes > 0) {
1178       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1179       if (collector_state()->in_marking_window()) {
1180         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1181       } else {
1182         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1183       }
1184     }
1185 
1186     if (young_cset_region_length() > 0) {
1187       _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1188                                                young_cset_region_length());
1189     }
1190 
1191     if (old_cset_region_length() > 0) {
1192       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1193                                                    old_cset_region_length());
1194     }
1195 
1196     _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1197 
1198     _pending_cards_seq->add((double) _pending_cards);
1199     _rs_lengths_seq->add((double) _max_rs_lengths);
1200   }
1201 
1202   collector_state()->set_in_marking_window(new_in_marking_window);
1203   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1204   _free_regions_at_end_of_collection = _g1->num_free_regions();
1205   // IHOP control wants to know the expected young gen length if it were not
1206   // restrained by the heap reserve. Using the actual length would make the
1207   // prediction too small and the limit the young gen every time we get to the
1208   // predicted target occupancy.
1209   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
1210   update_rs_lengths_prediction();
1211 
1212   // Only update IHOP information on regular GCs.
1213   if (update_stats) {
1214     double marking_to_mixed_time = -1.0;
1215     if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1216       marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1217       assert(marking_to_mixed_time > 0.0,
1218              "Initial mark to mixed time must be larger than zero but is %.3f",
1219              marking_to_mixed_time);
1220     }
1221 
1222     update_ihop_statistics(marking_to_mixed_time,
1223                            app_time_ms / 1000.0,
1224                            _last_old_allocated_bytes,
1225                            last_unrestrained_young_length * HeapRegion::GrainBytes);
1226   }
1227   _last_old_allocated_bytes = 0;
1228 
1229   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1230   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1231 
1232   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1233 
1234   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1235     ergo_verbose2(ErgoTiming,
1236                   "adjust concurrent refinement thresholds",
1237                   ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1238                   ergo_format_ms("Update RS time goal")
1239                   ergo_format_ms("Scan HCC time"),
1240                   update_rs_time_goal_ms,
1241                   scan_hcc_time_ms);
1242 
1243     update_rs_time_goal_ms = 0;
1244   } else {
1245     update_rs_time_goal_ms -= scan_hcc_time_ms;
1246   }
1247   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1248                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1249                                update_rs_time_goal_ms);
1250 
1251   _collectionSetChooser->verify();
1252 }
1253 
1254 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1255   return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1256                                  G1CollectedHeap::heap()->max_capacity());
1257 }
1258 
1259 void G1CollectorPolicy::update_ihop_statistics(double marking_time,
1260                                                double mutator_time_s,
1261                                                size_t mutator_alloc_bytes,
1262                                                size_t young_gen_size) {
1263   bool report = false;
1264 
1265   // To avoid using really small times that may be caused by e.g. back-to-back gcs
1266   // we filter them out.
1267   double const min_valid_time = 1e-6;
1268 
1269   if (marking_time > min_valid_time) {
1270     _ihop_control->update_marking_length(marking_time);
1271     report = true;
1272   }
1273 
1274   // As an approximation for the young gc promotion rates during marking we use
1275   // all of them. In many applications there are only a few if any young gcs during
1276   // marking, which makes any prediction useless. This increases the accuracy of the
1277   // prediction.
1278   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1279     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1280     report = true;
1281   }
1282 
1283   if (report) {
1284     report_ihop_statistics();
1285   }
1286 }
1287 
1288 void G1CollectorPolicy::report_ihop_statistics() {
1289   _ihop_control->print();
1290 }
1291 
1292 #define EXT_SIZE_FORMAT "%.1f%s"
1293 #define EXT_SIZE_PARAMS(bytes)                                  \
1294   byte_size_in_proper_unit((double)(bytes)),                    \
1295   proper_unit_for_byte_size((bytes))
1296 
1297 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1298   YoungList* young_list = _g1->young_list();
1299   _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1300   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1301   _heap_capacity_bytes_before_gc = _g1->capacity();
1302   _heap_used_bytes_before_gc = _g1->used();
1303   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1304 
1305   _eden_capacity_bytes_before_gc =
1306          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1307 
1308   if (full) {
1309     _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1310   }
1311 }
1312 
1313 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1314   size_t bytes_after = _g1->used();
1315   size_t capacity = _g1->capacity();
1316 
1317   gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1318       byte_size_in_proper_unit(bytes_before),
1319       proper_unit_for_byte_size(bytes_before),
1320       byte_size_in_proper_unit(bytes_after),
1321       proper_unit_for_byte_size(bytes_after),
1322       byte_size_in_proper_unit(capacity),
1323       proper_unit_for_byte_size(capacity));
1324 }
1325 
1326 void G1CollectorPolicy::print_heap_transition() const {
1327   print_heap_transition(_heap_used_bytes_before_gc);
1328 }
1329 
1330 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1331   YoungList* young_list = _g1->young_list();
1332 
1333   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1334   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1335   size_t heap_used_bytes_after_gc = _g1->used();
1336 
1337   size_t heap_capacity_bytes_after_gc = _g1->capacity();
1338   size_t eden_capacity_bytes_after_gc =
1339     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1340 
1341   gclog_or_tty->print(
1342     "   [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1343     "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1344     "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1345     EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1346     EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1347     EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1348     EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1349     EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1350     EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1351     EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1352     EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1353     EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1354     EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1355     EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1356 
1357   if (full) {
1358     MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1359   }
1360 
1361   gclog_or_tty->cr();
1362 }
1363 
1364 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1365   phase_times()->print(pause_time_sec);
1366 }
1367 
1368 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1369                                                      double update_rs_processed_buffers,
1370                                                      double goal_ms) {
1371   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1372   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1373 
1374   if (G1UseAdaptiveConcRefinement) {
1375     const int k_gy = 3, k_gr = 6;
1376     const double inc_k = 1.1, dec_k = 0.9;
1377 
1378     int g = cg1r->green_zone();
1379     if (update_rs_time > goal_ms) {
1380       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1381     } else {
1382       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1383         g = (int)MAX2(g * inc_k, g + 1.0);
1384       }
1385     }
1386     // Change the refinement threads params
1387     cg1r->set_green_zone(g);
1388     cg1r->set_yellow_zone(g * k_gy);
1389     cg1r->set_red_zone(g * k_gr);
1390     cg1r->reinitialize_threads();
1391 
1392     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1393     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1394                                     cg1r->yellow_zone());
1395     // Change the barrier params
1396     dcqs.set_process_completed_threshold(processing_threshold);
1397     dcqs.set_max_completed_queue(cg1r->red_zone());
1398   }
1399 
1400   int curr_queue_size = dcqs.completed_buffers_num();
1401   if (curr_queue_size >= cg1r->yellow_zone()) {
1402     dcqs.set_completed_queue_padding(curr_queue_size);
1403   } else {
1404     dcqs.set_completed_queue_padding(0);
1405   }
1406   dcqs.notify_if_necessary();
1407 }
1408 
1409 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1410   return (size_t) get_new_prediction(_rs_length_diff_seq);
1411 }
1412 
1413 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1414   return get_new_prediction(_alloc_rate_ms_seq);
1415 }
1416 
1417 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1418   return get_new_prediction(_cost_per_card_ms_seq);
1419 }
1420 
1421 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1422   return get_new_prediction(_cost_scan_hcc_seq);
1423 }
1424 
1425 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1426   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1427 }
1428 
1429 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1430   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1431 }
1432 
1433 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1434   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1435     return predict_young_cards_per_entry_ratio();
1436   } else {
1437     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1438   }
1439 }
1440 
1441 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1442   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1443 }
1444 
1445 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1446   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1447 }
1448 
1449 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1450   if (collector_state()->gcs_are_young()) {
1451     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1452   } else {
1453     return predict_mixed_rs_scan_time_ms(card_num);
1454   }
1455 }
1456 
1457 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1458   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1459     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1460   } else {
1461     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1462   }
1463 }
1464 
1465 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1466   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1467     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1468   } else {
1469     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1470   }
1471 }
1472 
1473 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1474   if (collector_state()->during_concurrent_mark()) {
1475     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1476   } else {
1477     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1478   }
1479 }
1480 
1481 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1482   return get_new_prediction(_constant_other_time_ms_seq);
1483 }
1484 
1485 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1486   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1487 }
1488 
1489 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1490   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1491 }
1492 
1493 double G1CollectorPolicy::predict_remark_time_ms() const {
1494   return get_new_prediction(_concurrent_mark_remark_times_ms);
1495 }
1496 
1497 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1498   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1499 }
1500 
1501 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1502   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1503   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1504   double pred = get_new_prediction(seq);
1505   if (pred > 1.0) {
1506     pred = 1.0;
1507   }
1508   return pred;
1509 }
1510 
1511 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1512   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1513 }
1514 
1515 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1516   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1517 }
1518 
1519 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1520                                                        size_t scanned_cards) const {
1521   return
1522     predict_rs_update_time_ms(pending_cards) +
1523     predict_rs_scan_time_ms(scanned_cards) +
1524     predict_constant_other_time_ms();
1525 }
1526 
1527 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1528   size_t rs_length = predict_rs_length_diff();
1529   size_t card_num;
1530   if (collector_state()->gcs_are_young()) {
1531     card_num = predict_young_card_num(rs_length);
1532   } else {
1533     card_num = predict_non_young_card_num(rs_length);
1534   }
1535   return predict_base_elapsed_time_ms(pending_cards, card_num);
1536 }
1537 
1538 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1539   size_t bytes_to_copy;
1540   if (hr->is_marked())
1541     bytes_to_copy = hr->max_live_bytes();
1542   else {
1543     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1544     int age = hr->age_in_surv_rate_group();
1545     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1546     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1547   }
1548   return bytes_to_copy;
1549 }
1550 
1551 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1552                                                          bool for_young_gc) const {
1553   size_t rs_length = hr->rem_set()->occupied();
1554   size_t card_num;
1555 
1556   // Predicting the number of cards is based on which type of GC
1557   // we're predicting for.
1558   if (for_young_gc) {
1559     card_num = predict_young_card_num(rs_length);
1560   } else {
1561     card_num = predict_non_young_card_num(rs_length);
1562   }
1563   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1564 
1565   double region_elapsed_time_ms =
1566     predict_rs_scan_time_ms(card_num) +
1567     predict_object_copy_time_ms(bytes_to_copy);
1568 
1569   // The prediction of the "other" time for this region is based
1570   // upon the region type and NOT the GC type.
1571   if (hr->is_young()) {
1572     region_elapsed_time_ms += predict_young_other_time_ms(1);
1573   } else {
1574     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1575   }
1576   return region_elapsed_time_ms;
1577 }
1578 
1579 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1580                                                  uint survivor_cset_region_length) {
1581   _eden_cset_region_length     = eden_cset_region_length;
1582   _survivor_cset_region_length = survivor_cset_region_length;
1583   _old_cset_region_length      = 0;
1584 }
1585 
1586 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1587   _recorded_rs_lengths = rs_lengths;
1588 }
1589 
1590 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1591                                                double elapsed_ms) {
1592   _recent_gc_times_ms->add(elapsed_ms);
1593   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1594   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1595 }
1596 
1597 size_t G1CollectorPolicy::expansion_amount() const {
1598   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1599   double threshold = _gc_overhead_perc;
1600   if (recent_gc_overhead > threshold) {
1601     // We will double the existing space, or take
1602     // G1ExpandByPercentOfAvailable % of the available expansion
1603     // space, whichever is smaller, bounded below by a minimum
1604     // expansion (unless that's all that's left.)
1605     const size_t min_expand_bytes = 1*M;
1606     size_t reserved_bytes = _g1->max_capacity();
1607     size_t committed_bytes = _g1->capacity();
1608     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1609     size_t expand_bytes;
1610     size_t expand_bytes_via_pct =
1611       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1612     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1613     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1614     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1615 
1616     ergo_verbose5(ErgoHeapSizing,
1617                   "attempt heap expansion",
1618                   ergo_format_reason("recent GC overhead higher than "
1619                                      "threshold after GC")
1620                   ergo_format_perc("recent GC overhead")
1621                   ergo_format_perc("threshold")
1622                   ergo_format_byte("uncommitted")
1623                   ergo_format_byte_perc("calculated expansion amount"),
1624                   recent_gc_overhead, threshold,
1625                   uncommitted_bytes,
1626                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1627 
1628     return expand_bytes;
1629   } else {
1630     return 0;
1631   }
1632 }
1633 
1634 void G1CollectorPolicy::print_tracing_info() const {
1635   _trace_young_gen_time_data.print();
1636   _trace_old_gen_time_data.print();
1637 }
1638 
1639 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1640 #ifndef PRODUCT
1641   _short_lived_surv_rate_group->print_surv_rate_summary();
1642   // add this call for any other surv rate groups
1643 #endif // PRODUCT
1644 }
1645 
1646 bool G1CollectorPolicy::is_young_list_full() const {
1647   uint young_list_length = _g1->young_list()->length();
1648   uint young_list_target_length = _young_list_target_length;
1649   return young_list_length >= young_list_target_length;
1650 }
1651 
1652 bool G1CollectorPolicy::can_expand_young_list() const {
1653   uint young_list_length = _g1->young_list()->length();
1654   uint young_list_max_length = _young_list_max_length;
1655   return young_list_length < young_list_max_length;
1656 }
1657 
1658 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1659   uint expansion_region_num = 0;
1660   if (GCLockerEdenExpansionPercent > 0) {
1661     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1662     double expansion_region_num_d = perc * (double) _young_list_target_length;
1663     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1664     // less than 1.0) we'll get 1.
1665     expansion_region_num = (uint) ceil(expansion_region_num_d);
1666   } else {
1667     assert(expansion_region_num == 0, "sanity");
1668   }
1669   _young_list_max_length = _young_list_target_length + expansion_region_num;
1670   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1671 }
1672 
1673 // Calculates survivor space parameters.
1674 void G1CollectorPolicy::update_survivors_policy() {
1675   double max_survivor_regions_d =
1676                  (double) _young_list_target_length / (double) SurvivorRatio;
1677   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1678   // smaller than 1.0) we'll get 1.
1679   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1680 
1681   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1682         HeapRegion::GrainWords * _max_survivor_regions, counters());
1683 }
1684 
1685 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1686   // We actually check whether we are marking here and not if we are in a
1687   // reclamation phase. This means that we will schedule a concurrent mark
1688   // even while we are still in the process of reclaiming memory.
1689   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1690   if (!during_cycle) {
1691     ergo_verbose1(ErgoConcCycles,
1692                   "request concurrent cycle initiation",
1693                   ergo_format_reason("requested by GC cause")
1694                   ergo_format_str("GC cause"),
1695                   GCCause::to_string(gc_cause));
1696     collector_state()->set_initiate_conc_mark_if_possible(true);
1697     return true;
1698   } else {
1699     ergo_verbose1(ErgoConcCycles,
1700                   "do not request concurrent cycle initiation",
1701                   ergo_format_reason("concurrent cycle already in progress")
1702                   ergo_format_str("GC cause"),
1703                   GCCause::to_string(gc_cause));
1704     return false;
1705   }
1706 }
1707 
1708 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1709   // We are about to decide on whether this pause will be an
1710   // initial-mark pause.
1711 
1712   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1713   // will set it here if we have to. However, it should be cleared by
1714   // the end of the pause (it's only set for the duration of an
1715   // initial-mark pause).
1716   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1717 
1718   if (collector_state()->initiate_conc_mark_if_possible()) {
1719     // We had noticed on a previous pause that the heap occupancy has
1720     // gone over the initiating threshold and we should start a
1721     // concurrent marking cycle. So we might initiate one.
1722 
1723     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1724       // Initiate a new initial mark only if there is no marking or reclamation going
1725       // on.
1726 
1727       collector_state()->set_during_initial_mark_pause(true);
1728       // And we can now clear initiate_conc_mark_if_possible() as
1729       // we've already acted on it.
1730       collector_state()->set_initiate_conc_mark_if_possible(false);
1731 
1732       ergo_verbose0(ErgoConcCycles,
1733                   "initiate concurrent cycle",
1734                   ergo_format_reason("concurrent cycle initiation requested"));
1735     } else {
1736       // The concurrent marking thread is still finishing up the
1737       // previous cycle. If we start one right now the two cycles
1738       // overlap. In particular, the concurrent marking thread might
1739       // be in the process of clearing the next marking bitmap (which
1740       // we will use for the next cycle if we start one). Starting a
1741       // cycle now will be bad given that parts of the marking
1742       // information might get cleared by the marking thread. And we
1743       // cannot wait for the marking thread to finish the cycle as it
1744       // periodically yields while clearing the next marking bitmap
1745       // and, if it's in a yield point, it's waiting for us to
1746       // finish. So, at this point we will not start a cycle and we'll
1747       // let the concurrent marking thread complete the last one.
1748       ergo_verbose0(ErgoConcCycles,
1749                     "do not initiate concurrent cycle",
1750                     ergo_format_reason("concurrent cycle already in progress"));
1751     }
1752   }
1753 }
1754 
1755 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1756   G1CollectedHeap* _g1h;
1757   CSetChooserParUpdater _cset_updater;
1758 
1759 public:
1760   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1761                            uint chunk_size) :
1762     _g1h(G1CollectedHeap::heap()),
1763     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1764 
1765   bool doHeapRegion(HeapRegion* r) {
1766     // Do we have any marking information for this region?
1767     if (r->is_marked()) {
1768       // We will skip any region that's currently used as an old GC
1769       // alloc region (we should not consider those for collection
1770       // before we fill them up).
1771       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1772         _cset_updater.add_region(r);
1773       }
1774     }
1775     return false;
1776   }
1777 };
1778 
1779 class ParKnownGarbageTask: public AbstractGangTask {
1780   CollectionSetChooser* _hrSorted;
1781   uint _chunk_size;
1782   G1CollectedHeap* _g1;
1783   HeapRegionClaimer _hrclaimer;
1784 
1785 public:
1786   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1787       AbstractGangTask("ParKnownGarbageTask"),
1788       _hrSorted(hrSorted), _chunk_size(chunk_size),
1789       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1790 
1791   void work(uint worker_id) {
1792     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1793     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1794   }
1795 };
1796 
1797 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1798   assert(n_workers > 0, "Active gc workers should be greater than 0");
1799   const uint overpartition_factor = 4;
1800   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1801   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1802 }
1803 
1804 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1805   _collectionSetChooser->clear();
1806 
1807   WorkGang* workers = _g1->workers();
1808   uint n_workers = workers->active_workers();
1809 
1810   uint n_regions = _g1->num_regions();
1811   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1812   _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1813   ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1814   workers->run_task(&par_known_garbage_task);
1815 
1816   _collectionSetChooser->sort_regions();
1817 
1818   double end_sec = os::elapsedTime();
1819   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1820   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1821   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1822   _prev_collection_pause_end_ms += elapsed_time_ms;
1823 
1824   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1825 }
1826 
1827 // Add the heap region at the head of the non-incremental collection set
1828 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1829   assert(_inc_cset_build_state == Active, "Precondition");
1830   assert(hr->is_old(), "the region should be old");
1831 
1832   assert(!hr->in_collection_set(), "should not already be in the CSet");
1833   _g1->register_old_region_with_cset(hr);
1834   hr->set_next_in_collection_set(_collection_set);
1835   _collection_set = hr;
1836   _collection_set_bytes_used_before += hr->used();
1837   size_t rs_length = hr->rem_set()->occupied();
1838   _recorded_rs_lengths += rs_length;
1839   _old_cset_region_length += 1;
1840 }
1841 
1842 // Initialize the per-collection-set information
1843 void G1CollectorPolicy::start_incremental_cset_building() {
1844   assert(_inc_cset_build_state == Inactive, "Precondition");
1845 
1846   _inc_cset_head = NULL;
1847   _inc_cset_tail = NULL;
1848   _inc_cset_bytes_used_before = 0;
1849 
1850   _inc_cset_max_finger = 0;
1851   _inc_cset_recorded_rs_lengths = 0;
1852   _inc_cset_recorded_rs_lengths_diffs = 0;
1853   _inc_cset_predicted_elapsed_time_ms = 0.0;
1854   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1855   _inc_cset_build_state = Active;
1856 }
1857 
1858 void G1CollectorPolicy::finalize_incremental_cset_building() {
1859   assert(_inc_cset_build_state == Active, "Precondition");
1860   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1861 
1862   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1863   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1864   // that adds a new region to the CSet. Further updates by the
1865   // concurrent refinement thread that samples the young RSet lengths
1866   // are accumulated in the *_diffs fields. Here we add the diffs to
1867   // the "main" fields.
1868 
1869   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1870     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1871   } else {
1872     // This is defensive. The diff should in theory be always positive
1873     // as RSets can only grow between GCs. However, given that we
1874     // sample their size concurrently with other threads updating them
1875     // it's possible that we might get the wrong size back, which
1876     // could make the calculations somewhat inaccurate.
1877     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1878     if (_inc_cset_recorded_rs_lengths >= diffs) {
1879       _inc_cset_recorded_rs_lengths -= diffs;
1880     } else {
1881       _inc_cset_recorded_rs_lengths = 0;
1882     }
1883   }
1884   _inc_cset_predicted_elapsed_time_ms +=
1885                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1886 
1887   _inc_cset_recorded_rs_lengths_diffs = 0;
1888   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1889 }
1890 
1891 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1892   // This routine is used when:
1893   // * adding survivor regions to the incremental cset at the end of an
1894   //   evacuation pause,
1895   // * adding the current allocation region to the incremental cset
1896   //   when it is retired, and
1897   // * updating existing policy information for a region in the
1898   //   incremental cset via young list RSet sampling.
1899   // Therefore this routine may be called at a safepoint by the
1900   // VM thread, or in-between safepoints by mutator threads (when
1901   // retiring the current allocation region) or a concurrent
1902   // refine thread (RSet sampling).
1903 
1904   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1905   size_t used_bytes = hr->used();
1906   _inc_cset_recorded_rs_lengths += rs_length;
1907   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1908   _inc_cset_bytes_used_before += used_bytes;
1909 
1910   // Cache the values we have added to the aggregated information
1911   // in the heap region in case we have to remove this region from
1912   // the incremental collection set, or it is updated by the
1913   // rset sampling code
1914   hr->set_recorded_rs_length(rs_length);
1915   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1916 }
1917 
1918 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1919                                                      size_t new_rs_length) {
1920   // Update the CSet information that is dependent on the new RS length
1921   assert(hr->is_young(), "Precondition");
1922   assert(!SafepointSynchronize::is_at_safepoint(),
1923                                                "should not be at a safepoint");
1924 
1925   // We could have updated _inc_cset_recorded_rs_lengths and
1926   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1927   // that atomically, as this code is executed by a concurrent
1928   // refinement thread, potentially concurrently with a mutator thread
1929   // allocating a new region and also updating the same fields. To
1930   // avoid the atomic operations we accumulate these updates on two
1931   // separate fields (*_diffs) and we'll just add them to the "main"
1932   // fields at the start of a GC.
1933 
1934   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1935   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1936   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1937 
1938   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1939   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1940   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1941   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1942 
1943   hr->set_recorded_rs_length(new_rs_length);
1944   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1945 }
1946 
1947 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1948   assert(hr->is_young(), "invariant");
1949   assert(hr->young_index_in_cset() > -1, "should have already been set");
1950   assert(_inc_cset_build_state == Active, "Precondition");
1951 
1952   // We need to clear and set the cached recorded/cached collection set
1953   // information in the heap region here (before the region gets added
1954   // to the collection set). An individual heap region's cached values
1955   // are calculated, aggregated with the policy collection set info,
1956   // and cached in the heap region here (initially) and (subsequently)
1957   // by the Young List sampling code.
1958 
1959   size_t rs_length = hr->rem_set()->occupied();
1960   add_to_incremental_cset_info(hr, rs_length);
1961 
1962   HeapWord* hr_end = hr->end();
1963   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1964 
1965   assert(!hr->in_collection_set(), "invariant");
1966   _g1->register_young_region_with_cset(hr);
1967   assert(hr->next_in_collection_set() == NULL, "invariant");
1968 }
1969 
1970 // Add the region at the RHS of the incremental cset
1971 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1972   // We should only ever be appending survivors at the end of a pause
1973   assert(hr->is_survivor(), "Logic");
1974 
1975   // Do the 'common' stuff
1976   add_region_to_incremental_cset_common(hr);
1977 
1978   // Now add the region at the right hand side
1979   if (_inc_cset_tail == NULL) {
1980     assert(_inc_cset_head == NULL, "invariant");
1981     _inc_cset_head = hr;
1982   } else {
1983     _inc_cset_tail->set_next_in_collection_set(hr);
1984   }
1985   _inc_cset_tail = hr;
1986 }
1987 
1988 // Add the region to the LHS of the incremental cset
1989 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1990   // Survivors should be added to the RHS at the end of a pause
1991   assert(hr->is_eden(), "Logic");
1992 
1993   // Do the 'common' stuff
1994   add_region_to_incremental_cset_common(hr);
1995 
1996   // Add the region at the left hand side
1997   hr->set_next_in_collection_set(_inc_cset_head);
1998   if (_inc_cset_head == NULL) {
1999     assert(_inc_cset_tail == NULL, "Invariant");
2000     _inc_cset_tail = hr;
2001   }
2002   _inc_cset_head = hr;
2003 }
2004 
2005 #ifndef PRODUCT
2006 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2007   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2008 
2009   st->print_cr("\nCollection_set:");
2010   HeapRegion* csr = list_head;
2011   while (csr != NULL) {
2012     HeapRegion* next = csr->next_in_collection_set();
2013     assert(csr->in_collection_set(), "bad CS");
2014     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2015                  HR_FORMAT_PARAMS(csr),
2016                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2017                  csr->age_in_surv_rate_group_cond());
2018     csr = next;
2019   }
2020 }
2021 #endif // !PRODUCT
2022 
2023 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2024   // Returns the given amount of reclaimable bytes (that represents
2025   // the amount of reclaimable space still to be collected) as a
2026   // percentage of the current heap capacity.
2027   size_t capacity_bytes = _g1->capacity();
2028   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2029 }
2030 
2031 void G1CollectorPolicy::maybe_start_marking() {
2032   if (need_to_start_conc_mark("end of GC")) {
2033     // Note: this might have already been set, if during the last
2034     // pause we decided to start a cycle but at the beginning of
2035     // this pause we decided to postpone it. That's OK.
2036     collector_state()->set_initiate_conc_mark_if_possible(true);
2037   }
2038 }
2039 
2040 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2041   assert(!collector_state()->full_collection(), "must be");
2042   if (collector_state()->during_initial_mark_pause()) {
2043     assert(collector_state()->last_gc_was_young(), "must be");
2044     assert(!collector_state()->last_young_gc(), "must be");
2045     return InitialMarkGC;
2046   } else if (collector_state()->last_young_gc()) {
2047     assert(!collector_state()->during_initial_mark_pause(), "must be");
2048     assert(collector_state()->last_gc_was_young(), "must be");   
2049     return LastYoungGC;
2050   } else if (!collector_state()->last_gc_was_young()) {
2051     assert(!collector_state()->during_initial_mark_pause(), "must be");
2052     assert(!collector_state()->last_young_gc(), "must be");
2053     return MixedGC;
2054   } else {
2055     assert(collector_state()->last_gc_was_young(), "must be");
2056     assert(!collector_state()->during_initial_mark_pause(), "must be");
2057     assert(!collector_state()->last_young_gc(), "must be");
2058     return YoungOnlyGC;
2059   }
2060 }
2061 
2062 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2063   // Manage the MMU tracker. For some reason it ignores Full GCs.
2064   if (kind != FullGC) {
2065     _mmu_tracker->add_pause(start, end);
2066   }
2067   // Manage the mutator time tracking from initial mark to first mixed gc.
2068   switch (kind) {
2069     case FullGC:
2070       abort_time_to_mixed_tracking();
2071       break;
2072     case Cleanup:
2073     case Remark:
2074     case YoungOnlyGC:
2075     case LastYoungGC:
2076       _initial_mark_to_mixed.add_pause(end - start);
2077       break;
2078     case InitialMarkGC:
2079       _initial_mark_to_mixed.record_initial_mark_end(end);
2080       break;
2081     case MixedGC:
2082       _initial_mark_to_mixed.record_mixed_gc_start(start);
2083       break;
2084     default:
2085       ShouldNotReachHere();
2086   }
2087 }
2088 
2089 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2090   _initial_mark_to_mixed.reset();
2091 }
2092 
2093 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2094                                                 const char* false_action_str) const {
2095   CollectionSetChooser* cset_chooser = _collectionSetChooser;
2096   if (cset_chooser->is_empty()) {
2097     ergo_verbose0(ErgoMixedGCs,
2098                   false_action_str,
2099                   ergo_format_reason("candidate old regions not available"));
2100     return false;
2101   }
2102 
2103   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2104   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2105   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2106   double threshold = (double) G1HeapWastePercent;
2107   if (reclaimable_perc <= threshold) {
2108     ergo_verbose4(ErgoMixedGCs,
2109               false_action_str,
2110               ergo_format_reason("reclaimable percentage not over threshold")
2111               ergo_format_region("candidate old regions")
2112               ergo_format_byte_perc("reclaimable")
2113               ergo_format_perc("threshold"),
2114               cset_chooser->remaining_regions(),
2115               reclaimable_bytes,
2116               reclaimable_perc, threshold);
2117     return false;
2118   }
2119 
2120   ergo_verbose4(ErgoMixedGCs,
2121                 true_action_str,
2122                 ergo_format_reason("candidate old regions available")
2123                 ergo_format_region("candidate old regions")
2124                 ergo_format_byte_perc("reclaimable")
2125                 ergo_format_perc("threshold"),
2126                 cset_chooser->remaining_regions(),
2127                 reclaimable_bytes,
2128                 reclaimable_perc, threshold);
2129   return true;
2130 }
2131 
2132 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2133   // The min old CSet region bound is based on the maximum desired
2134   // number of mixed GCs after a cycle. I.e., even if some old regions
2135   // look expensive, we should add them to the CSet anyway to make
2136   // sure we go through the available old regions in no more than the
2137   // maximum desired number of mixed GCs.
2138   //
2139   // The calculation is based on the number of marked regions we added
2140   // to the CSet chooser in the first place, not how many remain, so
2141   // that the result is the same during all mixed GCs that follow a cycle.
2142 
2143   const size_t region_num = (size_t) _collectionSetChooser->length();
2144   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2145   size_t result = region_num / gc_num;
2146   // emulate ceiling
2147   if (result * gc_num < region_num) {
2148     result += 1;
2149   }
2150   return (uint) result;
2151 }
2152 
2153 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2154   // The max old CSet region bound is based on the threshold expressed
2155   // as a percentage of the heap size. I.e., it should bound the
2156   // number of old regions added to the CSet irrespective of how many
2157   // of them are available.
2158 
2159   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2160   const size_t region_num = g1h->num_regions();
2161   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2162   size_t result = region_num * perc / 100;
2163   // emulate ceiling
2164   if (100 * result < region_num * perc) {
2165     result += 1;
2166   }
2167   return (uint) result;
2168 }
2169 
2170 
2171 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2172   double young_start_time_sec = os::elapsedTime();
2173 
2174   YoungList* young_list = _g1->young_list();
2175   finalize_incremental_cset_building();
2176 
2177   guarantee(target_pause_time_ms > 0.0,
2178             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2179   guarantee(_collection_set == NULL, "Precondition");
2180 
2181   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2182   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2183 
2184   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2185                 "start choosing CSet",
2186                 ergo_format_size("_pending_cards")
2187                 ergo_format_ms("predicted base time")
2188                 ergo_format_ms("remaining time")
2189                 ergo_format_ms("target pause time"),
2190                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2191 
2192   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2193 
2194   if (collector_state()->last_gc_was_young()) {
2195     _trace_young_gen_time_data.increment_young_collection_count();
2196   } else {
2197     _trace_young_gen_time_data.increment_mixed_collection_count();
2198   }
2199 
2200   // The young list is laid with the survivor regions from the previous
2201   // pause are appended to the RHS of the young list, i.e.
2202   //   [Newly Young Regions ++ Survivors from last pause].
2203 
2204   uint survivor_region_length = young_list->survivor_length();
2205   uint eden_region_length = young_list->eden_length();
2206   init_cset_region_lengths(eden_region_length, survivor_region_length);
2207 
2208   HeapRegion* hr = young_list->first_survivor_region();
2209   while (hr != NULL) {
2210     assert(hr->is_survivor(), "badly formed young list");
2211     // There is a convention that all the young regions in the CSet
2212     // are tagged as "eden", so we do this for the survivors here. We
2213     // use the special set_eden_pre_gc() as it doesn't check that the
2214     // region is free (which is not the case here).
2215     hr->set_eden_pre_gc();
2216     hr = hr->get_next_young_region();
2217   }
2218 
2219   // Clear the fields that point to the survivor list - they are all young now.
2220   young_list->clear_survivors();
2221 
2222   _collection_set = _inc_cset_head;
2223   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2224   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2225 
2226   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2227                 "add young regions to CSet",
2228                 ergo_format_region("eden")
2229                 ergo_format_region("survivors")
2230                 ergo_format_ms("predicted young region time")
2231                 ergo_format_ms("target pause time"),
2232                 eden_region_length, survivor_region_length,
2233                 _inc_cset_predicted_elapsed_time_ms,
2234                 target_pause_time_ms);
2235 
2236   // The number of recorded young regions is the incremental
2237   // collection set's current size
2238   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2239 
2240   double young_end_time_sec = os::elapsedTime();
2241   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2242 
2243   return time_remaining_ms;
2244 }
2245 
2246 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2247   double non_young_start_time_sec = os::elapsedTime();
2248   double predicted_old_time_ms = 0.0;
2249 
2250 
2251   if (!collector_state()->gcs_are_young()) {
2252     CollectionSetChooser* cset_chooser = _collectionSetChooser;
2253     cset_chooser->verify();
2254     const uint min_old_cset_length = calc_min_old_cset_length();
2255     const uint max_old_cset_length = calc_max_old_cset_length();
2256 
2257     uint expensive_region_num = 0;
2258     bool check_time_remaining = adaptive_young_list_length();
2259 
2260     HeapRegion* hr = cset_chooser->peek();
2261     while (hr != NULL) {
2262       if (old_cset_region_length() >= max_old_cset_length) {
2263         // Added maximum number of old regions to the CSet.
2264         ergo_verbose2(ErgoCSetConstruction,
2265                       "finish adding old regions to CSet",
2266                       ergo_format_reason("old CSet region num reached max")
2267                       ergo_format_region("old")
2268                       ergo_format_region("max"),
2269                       old_cset_region_length(), max_old_cset_length);
2270         break;
2271       }
2272 
2273 
2274       // Stop adding regions if the remaining reclaimable space is
2275       // not above G1HeapWastePercent.
2276       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2277       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2278       double threshold = (double) G1HeapWastePercent;
2279       if (reclaimable_perc <= threshold) {
2280         // We've added enough old regions that the amount of uncollected
2281         // reclaimable space is at or below the waste threshold. Stop
2282         // adding old regions to the CSet.
2283         ergo_verbose5(ErgoCSetConstruction,
2284                       "finish adding old regions to CSet",
2285                       ergo_format_reason("reclaimable percentage not over threshold")
2286                       ergo_format_region("old")
2287                       ergo_format_region("max")
2288                       ergo_format_byte_perc("reclaimable")
2289                       ergo_format_perc("threshold"),
2290                       old_cset_region_length(),
2291                       max_old_cset_length,
2292                       reclaimable_bytes,
2293                       reclaimable_perc, threshold);
2294         break;
2295       }
2296 
2297       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2298       if (check_time_remaining) {
2299         if (predicted_time_ms > time_remaining_ms) {
2300           // Too expensive for the current CSet.
2301 
2302           if (old_cset_region_length() >= min_old_cset_length) {
2303             // We have added the minimum number of old regions to the CSet,
2304             // we are done with this CSet.
2305             ergo_verbose4(ErgoCSetConstruction,
2306                           "finish adding old regions to CSet",
2307                           ergo_format_reason("predicted time is too high")
2308                           ergo_format_ms("predicted time")
2309                           ergo_format_ms("remaining time")
2310                           ergo_format_region("old")
2311                           ergo_format_region("min"),
2312                           predicted_time_ms, time_remaining_ms,
2313                           old_cset_region_length(), min_old_cset_length);
2314             break;
2315           }
2316 
2317           // We'll add it anyway given that we haven't reached the
2318           // minimum number of old regions.
2319           expensive_region_num += 1;
2320         }
2321       } else {
2322         if (old_cset_region_length() >= min_old_cset_length) {
2323           // In the non-auto-tuning case, we'll finish adding regions
2324           // to the CSet if we reach the minimum.
2325           ergo_verbose2(ErgoCSetConstruction,
2326                         "finish adding old regions to CSet",
2327                         ergo_format_reason("old CSet region num reached min")
2328                         ergo_format_region("old")
2329                         ergo_format_region("min"),
2330                         old_cset_region_length(), min_old_cset_length);
2331           break;
2332         }
2333       }
2334 
2335       // We will add this region to the CSet.
2336       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2337       predicted_old_time_ms += predicted_time_ms;
2338       cset_chooser->pop(); // already have region via peek()
2339       _g1->old_set_remove(hr);
2340       add_old_region_to_cset(hr);
2341 
2342       hr = cset_chooser->peek();
2343     }
2344     if (hr == NULL) {
2345       ergo_verbose0(ErgoCSetConstruction,
2346                     "finish adding old regions to CSet",
2347                     ergo_format_reason("candidate old regions not available"));
2348     }
2349 
2350     if (expensive_region_num > 0) {
2351       // We print the information once here at the end, predicated on
2352       // whether we added any apparently expensive regions or not, to
2353       // avoid generating output per region.
2354       ergo_verbose4(ErgoCSetConstruction,
2355                     "added expensive regions to CSet",
2356                     ergo_format_reason("old CSet region num not reached min")
2357                     ergo_format_region("old")
2358                     ergo_format_region("expensive")
2359                     ergo_format_region("min")
2360                     ergo_format_ms("remaining time"),
2361                     old_cset_region_length(),
2362                     expensive_region_num,
2363                     min_old_cset_length,
2364                     time_remaining_ms);
2365     }
2366 
2367     cset_chooser->verify();
2368   }
2369 
2370   stop_incremental_cset_building();
2371 
2372   ergo_verbose3(ErgoCSetConstruction,
2373                 "finish choosing CSet",
2374                 ergo_format_region("old")
2375                 ergo_format_ms("predicted old region time")
2376                 ergo_format_ms("time remaining"),
2377                 old_cset_region_length(),
2378                 predicted_old_time_ms, time_remaining_ms);
2379 
2380   double non_young_end_time_sec = os::elapsedTime();
2381   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2382 }
2383 
2384 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2385   if(TraceYoungGenTime) {
2386     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2387   }
2388 }
2389 
2390 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2391   if(TraceYoungGenTime) {
2392     _all_yield_times_ms.add(yield_time_ms);
2393   }
2394 }
2395 
2396 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2397   if(TraceYoungGenTime) {
2398     _total.add(pause_time_ms);
2399     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2400     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2401     _parallel.add(phase_times->cur_collection_par_time_ms());
2402     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2403     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2404     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2405     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2406     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2407     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2408 
2409     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2410       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2411       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2412       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2413       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2414       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2415 
2416     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2417     _parallel_other.add(parallel_other_time);
2418     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2419   }
2420 }
2421 
2422 void TraceYoungGenTimeData::increment_young_collection_count() {
2423   if(TraceYoungGenTime) {
2424     ++_young_pause_num;
2425   }
2426 }
2427 
2428 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2429   if(TraceYoungGenTime) {
2430     ++_mixed_pause_num;
2431   }
2432 }
2433 
2434 void TraceYoungGenTimeData::print_summary(const char* str,
2435                                           const NumberSeq* seq) const {
2436   double sum = seq->sum();
2437   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2438                 str, sum / 1000.0, seq->avg());
2439 }
2440 
2441 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2442                                              const NumberSeq* seq) const {
2443   print_summary(str, seq);
2444   gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2445                 "(num", seq->num(), seq->sd(), seq->maximum());
2446 }
2447 
2448 void TraceYoungGenTimeData::print() const {
2449   if (!TraceYoungGenTime) {
2450     return;
2451   }
2452 
2453   gclog_or_tty->print_cr("ALL PAUSES");
2454   print_summary_sd("   Total", &_total);
2455   gclog_or_tty->cr();
2456   gclog_or_tty->cr();
2457   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2458   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2459   gclog_or_tty->cr();
2460 
2461   gclog_or_tty->print_cr("EVACUATION PAUSES");
2462 
2463   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2464     gclog_or_tty->print_cr("none");
2465   } else {
2466     print_summary_sd("   Evacuation Pauses", &_total);
2467     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2468     print_summary("      Parallel Time", &_parallel);
2469     print_summary("         Ext Root Scanning", &_ext_root_scan);
2470     print_summary("         SATB Filtering", &_satb_filtering);
2471     print_summary("         Update RS", &_update_rs);
2472     print_summary("         Scan RS", &_scan_rs);
2473     print_summary("         Object Copy", &_obj_copy);
2474     print_summary("         Termination", &_termination);
2475     print_summary("         Parallel Other", &_parallel_other);
2476     print_summary("      Clear CT", &_clear_ct);
2477     print_summary("      Other", &_other);
2478   }
2479   gclog_or_tty->cr();
2480 
2481   gclog_or_tty->print_cr("MISC");
2482   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2483   print_summary_sd("   Yields", &_all_yield_times_ms);
2484 }
2485 
2486 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2487   if (TraceOldGenTime) {
2488     _all_full_gc_times.add(full_gc_time_ms);
2489   }
2490 }
2491 
2492 void TraceOldGenTimeData::print() const {
2493   if (!TraceOldGenTime) {
2494     return;
2495   }
2496 
2497   if (_all_full_gc_times.num() > 0) {
2498     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2499       _all_full_gc_times.num(),
2500       _all_full_gc_times.sum() / 1000.0);
2501     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2502     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2503       _all_full_gc_times.sd(),
2504       _all_full_gc_times.maximum());
2505   }
2506 }