rev 9416 : dihop-changes
rev 9418 : imported patch erik-jmasa-review
rev 9419 : imported patch fix-evac-failure-needs-stats

   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   update_ihop_prediction(app_time_ms / 1000.0,
1213                          _last_old_allocated_bytes,
1214                          last_unrestrained_young_length * HeapRegion::GrainBytes);
1215   _last_old_allocated_bytes = 0;
1216 
1217   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1218   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1219 
1220   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1221 
1222   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1223     ergo_verbose2(ErgoTiming,
1224                   "adjust concurrent refinement thresholds",
1225                   ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1226                   ergo_format_ms("Update RS time goal")
1227                   ergo_format_ms("Scan HCC time"),
1228                   update_rs_time_goal_ms,
1229                   scan_hcc_time_ms);
1230 
1231     update_rs_time_goal_ms = 0;
1232   } else {
1233     update_rs_time_goal_ms -= scan_hcc_time_ms;
1234   }
1235   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1236                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1237                                update_rs_time_goal_ms);
1238 
1239   _collectionSetChooser->verify();
1240 }
1241 
1242 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1243   return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1244                                  G1CollectedHeap::heap()->max_capacity());
1245 }
1246 
1247 void G1CollectorPolicy::update_ihop_prediction(double mutator_time_s,
1248                                                size_t mutator_alloc_bytes,
1249                                                size_t young_gen_size) {
1250   // Always try to update IHOP prediction. Even evacuation failures give information
1251   // about e.g. whether to start IHOP earlier next time.
1252 
1253   // Avoid using really small application times that might create samples with
1254   // very high or very low values. They may be caused by e.g. back-to-back gcs.
1255   double const min_valid_time = 1e-6;
1256 
1257   bool report = false;
1258 
1259   double marking_to_mixed_time = -1.0;
1260   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1261     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1262     assert(marking_to_mixed_time > 0.0,
1263            "Initial mark to mixed time must be larger than zero but is %.3f",
1264            marking_to_mixed_time);
1265     if (marking_to_mixed_time > min_valid_time) {
1266       _ihop_control->update_marking_length(marking_to_mixed_time);
1267       report = true;
1268     }
1269   }
1270 
1271   // As an approximation for the young gc promotion rates during marking we use
1272   // all of them. In many applications there are only a few if any young gcs during
1273   // marking, which makes any prediction useless. This increases the accuracy of the
1274   // prediction.
1275   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1276     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1277     report = true;
1278   }
1279 
1280   if (report) {
1281     report_ihop_statistics();
1282   }
1283 }
1284 
1285 void G1CollectorPolicy::report_ihop_statistics() {
1286   _ihop_control->print();
1287 }
1288 
1289 #define EXT_SIZE_FORMAT "%.1f%s"
1290 #define EXT_SIZE_PARAMS(bytes)                                  \
1291   byte_size_in_proper_unit((double)(bytes)),                    \
1292   proper_unit_for_byte_size((bytes))
1293 
1294 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1295   YoungList* young_list = _g1->young_list();
1296   _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1297   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1298   _heap_capacity_bytes_before_gc = _g1->capacity();
1299   _heap_used_bytes_before_gc = _g1->used();
1300   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1301 
1302   _eden_capacity_bytes_before_gc =
1303          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1304 
1305   if (full) {
1306     _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1307   }
1308 }
1309 
1310 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1311   size_t bytes_after = _g1->used();
1312   size_t capacity = _g1->capacity();
1313 
1314   gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1315       byte_size_in_proper_unit(bytes_before),
1316       proper_unit_for_byte_size(bytes_before),
1317       byte_size_in_proper_unit(bytes_after),
1318       proper_unit_for_byte_size(bytes_after),
1319       byte_size_in_proper_unit(capacity),
1320       proper_unit_for_byte_size(capacity));
1321 }
1322 
1323 void G1CollectorPolicy::print_heap_transition() const {
1324   print_heap_transition(_heap_used_bytes_before_gc);
1325 }
1326 
1327 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1328   YoungList* young_list = _g1->young_list();
1329 
1330   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1331   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1332   size_t heap_used_bytes_after_gc = _g1->used();
1333 
1334   size_t heap_capacity_bytes_after_gc = _g1->capacity();
1335   size_t eden_capacity_bytes_after_gc =
1336     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1337 
1338   gclog_or_tty->print(
1339     "   [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1340     "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1341     "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1342     EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1343     EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1344     EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1345     EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1346     EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1347     EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1348     EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1349     EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1350     EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1351     EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1352     EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1353 
1354   if (full) {
1355     MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1356   }
1357 
1358   gclog_or_tty->cr();
1359 }
1360 
1361 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1362   phase_times()->print(pause_time_sec);
1363 }
1364 
1365 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1366                                                      double update_rs_processed_buffers,
1367                                                      double goal_ms) {
1368   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1369   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1370 
1371   if (G1UseAdaptiveConcRefinement) {
1372     const int k_gy = 3, k_gr = 6;
1373     const double inc_k = 1.1, dec_k = 0.9;
1374 
1375     int g = cg1r->green_zone();
1376     if (update_rs_time > goal_ms) {
1377       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1378     } else {
1379       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1380         g = (int)MAX2(g * inc_k, g + 1.0);
1381       }
1382     }
1383     // Change the refinement threads params
1384     cg1r->set_green_zone(g);
1385     cg1r->set_yellow_zone(g * k_gy);
1386     cg1r->set_red_zone(g * k_gr);
1387     cg1r->reinitialize_threads();
1388 
1389     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1390     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1391                                     cg1r->yellow_zone());
1392     // Change the barrier params
1393     dcqs.set_process_completed_threshold(processing_threshold);
1394     dcqs.set_max_completed_queue(cg1r->red_zone());
1395   }
1396 
1397   int curr_queue_size = dcqs.completed_buffers_num();
1398   if (curr_queue_size >= cg1r->yellow_zone()) {
1399     dcqs.set_completed_queue_padding(curr_queue_size);
1400   } else {
1401     dcqs.set_completed_queue_padding(0);
1402   }
1403   dcqs.notify_if_necessary();
1404 }
1405 
1406 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1407   return (size_t) get_new_prediction(_rs_length_diff_seq);
1408 }
1409 
1410 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1411   return get_new_prediction(_alloc_rate_ms_seq);
1412 }
1413 
1414 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1415   return get_new_prediction(_cost_per_card_ms_seq);
1416 }
1417 
1418 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1419   return get_new_prediction(_cost_scan_hcc_seq);
1420 }
1421 
1422 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1423   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1424 }
1425 
1426 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1427   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1428 }
1429 
1430 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1431   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1432     return predict_young_cards_per_entry_ratio();
1433   } else {
1434     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1435   }
1436 }
1437 
1438 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1439   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1440 }
1441 
1442 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1443   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1444 }
1445 
1446 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1447   if (collector_state()->gcs_are_young()) {
1448     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1449   } else {
1450     return predict_mixed_rs_scan_time_ms(card_num);
1451   }
1452 }
1453 
1454 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1455   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1456     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1457   } else {
1458     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1459   }
1460 }
1461 
1462 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1463   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1464     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1465   } else {
1466     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1467   }
1468 }
1469 
1470 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1471   if (collector_state()->during_concurrent_mark()) {
1472     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1473   } else {
1474     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1475   }
1476 }
1477 
1478 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1479   return get_new_prediction(_constant_other_time_ms_seq);
1480 }
1481 
1482 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1483   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1484 }
1485 
1486 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1487   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1488 }
1489 
1490 double G1CollectorPolicy::predict_remark_time_ms() const {
1491   return get_new_prediction(_concurrent_mark_remark_times_ms);
1492 }
1493 
1494 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1495   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1496 }
1497 
1498 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1499   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1500   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1501   double pred = get_new_prediction(seq);
1502   if (pred > 1.0) {
1503     pred = 1.0;
1504   }
1505   return pred;
1506 }
1507 
1508 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1509   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1510 }
1511 
1512 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1513   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1514 }
1515 
1516 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1517                                                        size_t scanned_cards) const {
1518   return
1519     predict_rs_update_time_ms(pending_cards) +
1520     predict_rs_scan_time_ms(scanned_cards) +
1521     predict_constant_other_time_ms();
1522 }
1523 
1524 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1525   size_t rs_length = predict_rs_length_diff();
1526   size_t card_num;
1527   if (collector_state()->gcs_are_young()) {
1528     card_num = predict_young_card_num(rs_length);
1529   } else {
1530     card_num = predict_non_young_card_num(rs_length);
1531   }
1532   return predict_base_elapsed_time_ms(pending_cards, card_num);
1533 }
1534 
1535 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1536   size_t bytes_to_copy;
1537   if (hr->is_marked())
1538     bytes_to_copy = hr->max_live_bytes();
1539   else {
1540     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1541     int age = hr->age_in_surv_rate_group();
1542     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1543     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1544   }
1545   return bytes_to_copy;
1546 }
1547 
1548 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1549                                                          bool for_young_gc) const {
1550   size_t rs_length = hr->rem_set()->occupied();
1551   size_t card_num;
1552 
1553   // Predicting the number of cards is based on which type of GC
1554   // we're predicting for.
1555   if (for_young_gc) {
1556     card_num = predict_young_card_num(rs_length);
1557   } else {
1558     card_num = predict_non_young_card_num(rs_length);
1559   }
1560   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1561 
1562   double region_elapsed_time_ms =
1563     predict_rs_scan_time_ms(card_num) +
1564     predict_object_copy_time_ms(bytes_to_copy);
1565 
1566   // The prediction of the "other" time for this region is based
1567   // upon the region type and NOT the GC type.
1568   if (hr->is_young()) {
1569     region_elapsed_time_ms += predict_young_other_time_ms(1);
1570   } else {
1571     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1572   }
1573   return region_elapsed_time_ms;
1574 }
1575 
1576 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1577                                                  uint survivor_cset_region_length) {
1578   _eden_cset_region_length     = eden_cset_region_length;
1579   _survivor_cset_region_length = survivor_cset_region_length;
1580   _old_cset_region_length      = 0;
1581 }
1582 
1583 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1584   _recorded_rs_lengths = rs_lengths;
1585 }
1586 
1587 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1588                                                double elapsed_ms) {
1589   _recent_gc_times_ms->add(elapsed_ms);
1590   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1591   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1592 }
1593 
1594 size_t G1CollectorPolicy::expansion_amount() const {
1595   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1596   double threshold = _gc_overhead_perc;
1597   if (recent_gc_overhead > threshold) {
1598     // We will double the existing space, or take
1599     // G1ExpandByPercentOfAvailable % of the available expansion
1600     // space, whichever is smaller, bounded below by a minimum
1601     // expansion (unless that's all that's left.)
1602     const size_t min_expand_bytes = 1*M;
1603     size_t reserved_bytes = _g1->max_capacity();
1604     size_t committed_bytes = _g1->capacity();
1605     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1606     size_t expand_bytes;
1607     size_t expand_bytes_via_pct =
1608       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1609     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1610     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1611     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1612 
1613     ergo_verbose5(ErgoHeapSizing,
1614                   "attempt heap expansion",
1615                   ergo_format_reason("recent GC overhead higher than "
1616                                      "threshold after GC")
1617                   ergo_format_perc("recent GC overhead")
1618                   ergo_format_perc("threshold")
1619                   ergo_format_byte("uncommitted")
1620                   ergo_format_byte_perc("calculated expansion amount"),
1621                   recent_gc_overhead, threshold,
1622                   uncommitted_bytes,
1623                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1624 
1625     return expand_bytes;
1626   } else {
1627     return 0;
1628   }
1629 }
1630 
1631 void G1CollectorPolicy::print_tracing_info() const {
1632   _trace_young_gen_time_data.print();
1633   _trace_old_gen_time_data.print();
1634 }
1635 
1636 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1637 #ifndef PRODUCT
1638   _short_lived_surv_rate_group->print_surv_rate_summary();
1639   // add this call for any other surv rate groups
1640 #endif // PRODUCT
1641 }
1642 
1643 bool G1CollectorPolicy::is_young_list_full() const {
1644   uint young_list_length = _g1->young_list()->length();
1645   uint young_list_target_length = _young_list_target_length;
1646   return young_list_length >= young_list_target_length;
1647 }
1648 
1649 bool G1CollectorPolicy::can_expand_young_list() const {
1650   uint young_list_length = _g1->young_list()->length();
1651   uint young_list_max_length = _young_list_max_length;
1652   return young_list_length < young_list_max_length;
1653 }
1654 
1655 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1656   uint expansion_region_num = 0;
1657   if (GCLockerEdenExpansionPercent > 0) {
1658     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1659     double expansion_region_num_d = perc * (double) _young_list_target_length;
1660     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1661     // less than 1.0) we'll get 1.
1662     expansion_region_num = (uint) ceil(expansion_region_num_d);
1663   } else {
1664     assert(expansion_region_num == 0, "sanity");
1665   }
1666   _young_list_max_length = _young_list_target_length + expansion_region_num;
1667   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1668 }
1669 
1670 // Calculates survivor space parameters.
1671 void G1CollectorPolicy::update_survivors_policy() {
1672   double max_survivor_regions_d =
1673                  (double) _young_list_target_length / (double) SurvivorRatio;
1674   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1675   // smaller than 1.0) we'll get 1.
1676   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1677 
1678   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1679         HeapRegion::GrainWords * _max_survivor_regions, counters());
1680 }
1681 
1682 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1683   // We actually check whether we are marking here and not if we are in a
1684   // reclamation phase. This means that we will schedule a concurrent mark
1685   // even while we are still in the process of reclaiming memory.
1686   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1687   if (!during_cycle) {
1688     ergo_verbose1(ErgoConcCycles,
1689                   "request concurrent cycle initiation",
1690                   ergo_format_reason("requested by GC cause")
1691                   ergo_format_str("GC cause"),
1692                   GCCause::to_string(gc_cause));
1693     collector_state()->set_initiate_conc_mark_if_possible(true);
1694     return true;
1695   } else {
1696     ergo_verbose1(ErgoConcCycles,
1697                   "do not request concurrent cycle initiation",
1698                   ergo_format_reason("concurrent cycle already in progress")
1699                   ergo_format_str("GC cause"),
1700                   GCCause::to_string(gc_cause));
1701     return false;
1702   }
1703 }
1704 
1705 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1706   // We are about to decide on whether this pause will be an
1707   // initial-mark pause.
1708 
1709   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1710   // will set it here if we have to. However, it should be cleared by
1711   // the end of the pause (it's only set for the duration of an
1712   // initial-mark pause).
1713   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1714 
1715   if (collector_state()->initiate_conc_mark_if_possible()) {
1716     // We had noticed on a previous pause that the heap occupancy has
1717     // gone over the initiating threshold and we should start a
1718     // concurrent marking cycle. So we might initiate one.
1719 
1720     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1721       // Initiate a new initial mark only if there is no marking or reclamation going
1722       // on.
1723 
1724       collector_state()->set_during_initial_mark_pause(true);
1725       // And we can now clear initiate_conc_mark_if_possible() as
1726       // we've already acted on it.
1727       collector_state()->set_initiate_conc_mark_if_possible(false);
1728 
1729       ergo_verbose0(ErgoConcCycles,
1730                   "initiate concurrent cycle",
1731                   ergo_format_reason("concurrent cycle initiation requested"));
1732     } else {
1733       // The concurrent marking thread is still finishing up the
1734       // previous cycle. If we start one right now the two cycles
1735       // overlap. In particular, the concurrent marking thread might
1736       // be in the process of clearing the next marking bitmap (which
1737       // we will use for the next cycle if we start one). Starting a
1738       // cycle now will be bad given that parts of the marking
1739       // information might get cleared by the marking thread. And we
1740       // cannot wait for the marking thread to finish the cycle as it
1741       // periodically yields while clearing the next marking bitmap
1742       // and, if it's in a yield point, it's waiting for us to
1743       // finish. So, at this point we will not start a cycle and we'll
1744       // let the concurrent marking thread complete the last one.
1745       ergo_verbose0(ErgoConcCycles,
1746                     "do not initiate concurrent cycle",
1747                     ergo_format_reason("concurrent cycle already in progress"));
1748     }
1749   }
1750 }
1751 
1752 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1753   G1CollectedHeap* _g1h;
1754   CSetChooserParUpdater _cset_updater;
1755 
1756 public:
1757   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1758                            uint chunk_size) :
1759     _g1h(G1CollectedHeap::heap()),
1760     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1761 
1762   bool doHeapRegion(HeapRegion* r) {
1763     // Do we have any marking information for this region?
1764     if (r->is_marked()) {
1765       // We will skip any region that's currently used as an old GC
1766       // alloc region (we should not consider those for collection
1767       // before we fill them up).
1768       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1769         _cset_updater.add_region(r);
1770       }
1771     }
1772     return false;
1773   }
1774 };
1775 
1776 class ParKnownGarbageTask: public AbstractGangTask {
1777   CollectionSetChooser* _hrSorted;
1778   uint _chunk_size;
1779   G1CollectedHeap* _g1;
1780   HeapRegionClaimer _hrclaimer;
1781 
1782 public:
1783   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1784       AbstractGangTask("ParKnownGarbageTask"),
1785       _hrSorted(hrSorted), _chunk_size(chunk_size),
1786       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1787 
1788   void work(uint worker_id) {
1789     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1790     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1791   }
1792 };
1793 
1794 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1795   assert(n_workers > 0, "Active gc workers should be greater than 0");
1796   const uint overpartition_factor = 4;
1797   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1798   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1799 }
1800 
1801 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {

1802   _collectionSetChooser->clear();
1803 
1804   WorkGang* workers = _g1->workers();
1805   uint n_workers = workers->active_workers();
1806 
1807   uint n_regions = _g1->num_regions();
1808   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1809   _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1810   ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1811   workers->run_task(&par_known_garbage_task);
1812 
1813   _collectionSetChooser->sort_regions();
1814 
1815   double end_sec = os::elapsedTime();
1816   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1817   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1818   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1819   _prev_collection_pause_end_ms += elapsed_time_ms;
1820 
1821   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1822 }
1823 
1824 // Add the heap region at the head of the non-incremental collection set
1825 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1826   assert(_inc_cset_build_state == Active, "Precondition");
1827   assert(hr->is_old(), "the region should be old");
1828 
1829   assert(!hr->in_collection_set(), "should not already be in the CSet");
1830   _g1->register_old_region_with_cset(hr);
1831   hr->set_next_in_collection_set(_collection_set);
1832   _collection_set = hr;
1833   _collection_set_bytes_used_before += hr->used();
1834   size_t rs_length = hr->rem_set()->occupied();
1835   _recorded_rs_lengths += rs_length;
1836   _old_cset_region_length += 1;
1837 }
1838 
1839 // Initialize the per-collection-set information
1840 void G1CollectorPolicy::start_incremental_cset_building() {
1841   assert(_inc_cset_build_state == Inactive, "Precondition");
1842 
1843   _inc_cset_head = NULL;
1844   _inc_cset_tail = NULL;
1845   _inc_cset_bytes_used_before = 0;
1846 
1847   _inc_cset_max_finger = 0;
1848   _inc_cset_recorded_rs_lengths = 0;
1849   _inc_cset_recorded_rs_lengths_diffs = 0;
1850   _inc_cset_predicted_elapsed_time_ms = 0.0;
1851   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1852   _inc_cset_build_state = Active;
1853 }
1854 
1855 void G1CollectorPolicy::finalize_incremental_cset_building() {
1856   assert(_inc_cset_build_state == Active, "Precondition");
1857   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1858 
1859   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1860   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1861   // that adds a new region to the CSet. Further updates by the
1862   // concurrent refinement thread that samples the young RSet lengths
1863   // are accumulated in the *_diffs fields. Here we add the diffs to
1864   // the "main" fields.
1865 
1866   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1867     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1868   } else {
1869     // This is defensive. The diff should in theory be always positive
1870     // as RSets can only grow between GCs. However, given that we
1871     // sample their size concurrently with other threads updating them
1872     // it's possible that we might get the wrong size back, which
1873     // could make the calculations somewhat inaccurate.
1874     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1875     if (_inc_cset_recorded_rs_lengths >= diffs) {
1876       _inc_cset_recorded_rs_lengths -= diffs;
1877     } else {
1878       _inc_cset_recorded_rs_lengths = 0;
1879     }
1880   }
1881   _inc_cset_predicted_elapsed_time_ms +=
1882                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1883 
1884   _inc_cset_recorded_rs_lengths_diffs = 0;
1885   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1886 }
1887 
1888 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1889   // This routine is used when:
1890   // * adding survivor regions to the incremental cset at the end of an
1891   //   evacuation pause,
1892   // * adding the current allocation region to the incremental cset
1893   //   when it is retired, and
1894   // * updating existing policy information for a region in the
1895   //   incremental cset via young list RSet sampling.
1896   // Therefore this routine may be called at a safepoint by the
1897   // VM thread, or in-between safepoints by mutator threads (when
1898   // retiring the current allocation region) or a concurrent
1899   // refine thread (RSet sampling).
1900 
1901   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1902   size_t used_bytes = hr->used();
1903   _inc_cset_recorded_rs_lengths += rs_length;
1904   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1905   _inc_cset_bytes_used_before += used_bytes;
1906 
1907   // Cache the values we have added to the aggregated information
1908   // in the heap region in case we have to remove this region from
1909   // the incremental collection set, or it is updated by the
1910   // rset sampling code
1911   hr->set_recorded_rs_length(rs_length);
1912   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1913 }
1914 
1915 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1916                                                      size_t new_rs_length) {
1917   // Update the CSet information that is dependent on the new RS length
1918   assert(hr->is_young(), "Precondition");
1919   assert(!SafepointSynchronize::is_at_safepoint(),
1920                                                "should not be at a safepoint");
1921 
1922   // We could have updated _inc_cset_recorded_rs_lengths and
1923   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1924   // that atomically, as this code is executed by a concurrent
1925   // refinement thread, potentially concurrently with a mutator thread
1926   // allocating a new region and also updating the same fields. To
1927   // avoid the atomic operations we accumulate these updates on two
1928   // separate fields (*_diffs) and we'll just add them to the "main"
1929   // fields at the start of a GC.
1930 
1931   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1932   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1933   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1934 
1935   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1936   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1937   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1938   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1939 
1940   hr->set_recorded_rs_length(new_rs_length);
1941   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1942 }
1943 
1944 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1945   assert(hr->is_young(), "invariant");
1946   assert(hr->young_index_in_cset() > -1, "should have already been set");
1947   assert(_inc_cset_build_state == Active, "Precondition");
1948 
1949   // We need to clear and set the cached recorded/cached collection set
1950   // information in the heap region here (before the region gets added
1951   // to the collection set). An individual heap region's cached values
1952   // are calculated, aggregated with the policy collection set info,
1953   // and cached in the heap region here (initially) and (subsequently)
1954   // by the Young List sampling code.
1955 
1956   size_t rs_length = hr->rem_set()->occupied();
1957   add_to_incremental_cset_info(hr, rs_length);
1958 
1959   HeapWord* hr_end = hr->end();
1960   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1961 
1962   assert(!hr->in_collection_set(), "invariant");
1963   _g1->register_young_region_with_cset(hr);
1964   assert(hr->next_in_collection_set() == NULL, "invariant");
1965 }
1966 
1967 // Add the region at the RHS of the incremental cset
1968 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1969   // We should only ever be appending survivors at the end of a pause
1970   assert(hr->is_survivor(), "Logic");
1971 
1972   // Do the 'common' stuff
1973   add_region_to_incremental_cset_common(hr);
1974 
1975   // Now add the region at the right hand side
1976   if (_inc_cset_tail == NULL) {
1977     assert(_inc_cset_head == NULL, "invariant");
1978     _inc_cset_head = hr;
1979   } else {
1980     _inc_cset_tail->set_next_in_collection_set(hr);
1981   }
1982   _inc_cset_tail = hr;
1983 }
1984 
1985 // Add the region to the LHS of the incremental cset
1986 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1987   // Survivors should be added to the RHS at the end of a pause
1988   assert(hr->is_eden(), "Logic");
1989 
1990   // Do the 'common' stuff
1991   add_region_to_incremental_cset_common(hr);
1992 
1993   // Add the region at the left hand side
1994   hr->set_next_in_collection_set(_inc_cset_head);
1995   if (_inc_cset_head == NULL) {
1996     assert(_inc_cset_tail == NULL, "Invariant");
1997     _inc_cset_tail = hr;
1998   }
1999   _inc_cset_head = hr;
2000 }
2001 
2002 #ifndef PRODUCT
2003 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2004   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2005 
2006   st->print_cr("\nCollection_set:");
2007   HeapRegion* csr = list_head;
2008   while (csr != NULL) {
2009     HeapRegion* next = csr->next_in_collection_set();
2010     assert(csr->in_collection_set(), "bad CS");
2011     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2012                  HR_FORMAT_PARAMS(csr),
2013                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2014                  csr->age_in_surv_rate_group_cond());
2015     csr = next;
2016   }
2017 }
2018 #endif // !PRODUCT
2019 
2020 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2021   // Returns the given amount of reclaimable bytes (that represents
2022   // the amount of reclaimable space still to be collected) as a
2023   // percentage of the current heap capacity.
2024   size_t capacity_bytes = _g1->capacity();
2025   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2026 }
2027 
2028 void G1CollectorPolicy::maybe_start_marking() {
2029   if (need_to_start_conc_mark("end of GC")) {
2030     // Note: this might have already been set, if during the last
2031     // pause we decided to start a cycle but at the beginning of
2032     // this pause we decided to postpone it. That's OK.
2033     collector_state()->set_initiate_conc_mark_if_possible(true);
2034   }
2035 }
2036 
2037 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2038   assert(!collector_state()->full_collection(), "must be");
2039   if (collector_state()->during_initial_mark_pause()) {
2040     assert(collector_state()->last_gc_was_young(), "must be");
2041     assert(!collector_state()->last_young_gc(), "must be");
2042     return InitialMarkGC;
2043   } else if (collector_state()->last_young_gc()) {
2044     assert(!collector_state()->during_initial_mark_pause(), "must be");
2045     assert(collector_state()->last_gc_was_young(), "must be");   
2046     return LastYoungGC;
2047   } else if (!collector_state()->last_gc_was_young()) {
2048     assert(!collector_state()->during_initial_mark_pause(), "must be");
2049     assert(!collector_state()->last_young_gc(), "must be");
2050     return MixedGC;
2051   } else {
2052     assert(collector_state()->last_gc_was_young(), "must be");
2053     assert(!collector_state()->during_initial_mark_pause(), "must be");
2054     assert(!collector_state()->last_young_gc(), "must be");
2055     return YoungOnlyGC;
2056   }
2057 }
2058 
2059 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2060   // Manage the MMU tracker. For some reason it ignores Full GCs.
2061   if (kind != FullGC) {
2062     _mmu_tracker->add_pause(start, end);
2063   }
2064   // Manage the mutator time tracking from initial mark to first mixed gc.
2065   switch (kind) {
2066     case FullGC:
2067       abort_time_to_mixed_tracking();
2068       break;
2069     case Cleanup:
2070     case Remark:
2071     case YoungOnlyGC:
2072     case LastYoungGC:
2073       _initial_mark_to_mixed.add_pause(end - start);
2074       break;
2075     case InitialMarkGC:
2076       _initial_mark_to_mixed.record_initial_mark_end(end);
2077       break;
2078     case MixedGC:
2079       _initial_mark_to_mixed.record_mixed_gc_start(start);
2080       break;
2081     default:
2082       ShouldNotReachHere();
2083   }
2084 }
2085 
2086 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2087   _initial_mark_to_mixed.reset();
2088 }
2089 
2090 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2091                                                 const char* false_action_str) const {
2092   CollectionSetChooser* cset_chooser = _collectionSetChooser;
2093   if (cset_chooser->is_empty()) {
2094     ergo_verbose0(ErgoMixedGCs,
2095                   false_action_str,
2096                   ergo_format_reason("candidate old regions not available"));
2097     return false;
2098   }
2099 
2100   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2101   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2102   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2103   double threshold = (double) G1HeapWastePercent;
2104   if (reclaimable_perc <= threshold) {
2105     ergo_verbose4(ErgoMixedGCs,
2106               false_action_str,
2107               ergo_format_reason("reclaimable percentage not over threshold")
2108               ergo_format_region("candidate old regions")
2109               ergo_format_byte_perc("reclaimable")
2110               ergo_format_perc("threshold"),
2111               cset_chooser->remaining_regions(),
2112               reclaimable_bytes,
2113               reclaimable_perc, threshold);
2114     return false;
2115   }
2116 
2117   ergo_verbose4(ErgoMixedGCs,
2118                 true_action_str,
2119                 ergo_format_reason("candidate old regions available")
2120                 ergo_format_region("candidate old regions")
2121                 ergo_format_byte_perc("reclaimable")
2122                 ergo_format_perc("threshold"),
2123                 cset_chooser->remaining_regions(),
2124                 reclaimable_bytes,
2125                 reclaimable_perc, threshold);
2126   return true;
2127 }
2128 
2129 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2130   // The min old CSet region bound is based on the maximum desired
2131   // number of mixed GCs after a cycle. I.e., even if some old regions
2132   // look expensive, we should add them to the CSet anyway to make
2133   // sure we go through the available old regions in no more than the
2134   // maximum desired number of mixed GCs.
2135   //
2136   // The calculation is based on the number of marked regions we added
2137   // to the CSet chooser in the first place, not how many remain, so
2138   // that the result is the same during all mixed GCs that follow a cycle.
2139 
2140   const size_t region_num = (size_t) _collectionSetChooser->length();
2141   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2142   size_t result = region_num / gc_num;
2143   // emulate ceiling
2144   if (result * gc_num < region_num) {
2145     result += 1;
2146   }
2147   return (uint) result;
2148 }
2149 
2150 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2151   // The max old CSet region bound is based on the threshold expressed
2152   // as a percentage of the heap size. I.e., it should bound the
2153   // number of old regions added to the CSet irrespective of how many
2154   // of them are available.
2155 
2156   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2157   const size_t region_num = g1h->num_regions();
2158   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2159   size_t result = region_num * perc / 100;
2160   // emulate ceiling
2161   if (100 * result < region_num * perc) {
2162     result += 1;
2163   }
2164   return (uint) result;
2165 }
2166 
2167 
2168 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2169   double young_start_time_sec = os::elapsedTime();
2170 
2171   YoungList* young_list = _g1->young_list();
2172   finalize_incremental_cset_building();
2173 
2174   guarantee(target_pause_time_ms > 0.0,
2175             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2176   guarantee(_collection_set == NULL, "Precondition");
2177 
2178   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2179   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2180 
2181   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2182                 "start choosing CSet",
2183                 ergo_format_size("_pending_cards")
2184                 ergo_format_ms("predicted base time")
2185                 ergo_format_ms("remaining time")
2186                 ergo_format_ms("target pause time"),
2187                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2188 
2189   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2190 
2191   if (collector_state()->last_gc_was_young()) {
2192     _trace_young_gen_time_data.increment_young_collection_count();
2193   } else {
2194     _trace_young_gen_time_data.increment_mixed_collection_count();
2195   }
2196 
2197   // The young list is laid with the survivor regions from the previous
2198   // pause are appended to the RHS of the young list, i.e.
2199   //   [Newly Young Regions ++ Survivors from last pause].
2200 
2201   uint survivor_region_length = young_list->survivor_length();
2202   uint eden_region_length = young_list->eden_length();
2203   init_cset_region_lengths(eden_region_length, survivor_region_length);
2204 
2205   HeapRegion* hr = young_list->first_survivor_region();
2206   while (hr != NULL) {
2207     assert(hr->is_survivor(), "badly formed young list");
2208     // There is a convention that all the young regions in the CSet
2209     // are tagged as "eden", so we do this for the survivors here. We
2210     // use the special set_eden_pre_gc() as it doesn't check that the
2211     // region is free (which is not the case here).
2212     hr->set_eden_pre_gc();
2213     hr = hr->get_next_young_region();
2214   }
2215 
2216   // Clear the fields that point to the survivor list - they are all young now.
2217   young_list->clear_survivors();
2218 
2219   _collection_set = _inc_cset_head;
2220   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2221   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2222 
2223   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2224                 "add young regions to CSet",
2225                 ergo_format_region("eden")
2226                 ergo_format_region("survivors")
2227                 ergo_format_ms("predicted young region time")
2228                 ergo_format_ms("target pause time"),
2229                 eden_region_length, survivor_region_length,
2230                 _inc_cset_predicted_elapsed_time_ms,
2231                 target_pause_time_ms);
2232 
2233   // The number of recorded young regions is the incremental
2234   // collection set's current size
2235   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2236 
2237   double young_end_time_sec = os::elapsedTime();
2238   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2239 
2240   return time_remaining_ms;
2241 }
2242 
2243 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2244   double non_young_start_time_sec = os::elapsedTime();
2245   double predicted_old_time_ms = 0.0;
2246 
2247 
2248   if (!collector_state()->gcs_are_young()) {
2249     CollectionSetChooser* cset_chooser = _collectionSetChooser;
2250     cset_chooser->verify();
2251     const uint min_old_cset_length = calc_min_old_cset_length();
2252     const uint max_old_cset_length = calc_max_old_cset_length();
2253 
2254     uint expensive_region_num = 0;
2255     bool check_time_remaining = adaptive_young_list_length();
2256 
2257     HeapRegion* hr = cset_chooser->peek();
2258     while (hr != NULL) {
2259       if (old_cset_region_length() >= max_old_cset_length) {
2260         // Added maximum number of old regions to the CSet.
2261         ergo_verbose2(ErgoCSetConstruction,
2262                       "finish adding old regions to CSet",
2263                       ergo_format_reason("old CSet region num reached max")
2264                       ergo_format_region("old")
2265                       ergo_format_region("max"),
2266                       old_cset_region_length(), max_old_cset_length);
2267         break;
2268       }
2269 
2270 
2271       // Stop adding regions if the remaining reclaimable space is
2272       // not above G1HeapWastePercent.
2273       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2274       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2275       double threshold = (double) G1HeapWastePercent;
2276       if (reclaimable_perc <= threshold) {
2277         // We've added enough old regions that the amount of uncollected
2278         // reclaimable space is at or below the waste threshold. Stop
2279         // adding old regions to the CSet.
2280         ergo_verbose5(ErgoCSetConstruction,
2281                       "finish adding old regions to CSet",
2282                       ergo_format_reason("reclaimable percentage not over threshold")
2283                       ergo_format_region("old")
2284                       ergo_format_region("max")
2285                       ergo_format_byte_perc("reclaimable")
2286                       ergo_format_perc("threshold"),
2287                       old_cset_region_length(),
2288                       max_old_cset_length,
2289                       reclaimable_bytes,
2290                       reclaimable_perc, threshold);
2291         break;
2292       }
2293 
2294       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2295       if (check_time_remaining) {
2296         if (predicted_time_ms > time_remaining_ms) {
2297           // Too expensive for the current CSet.
2298 
2299           if (old_cset_region_length() >= min_old_cset_length) {
2300             // We have added the minimum number of old regions to the CSet,
2301             // we are done with this CSet.
2302             ergo_verbose4(ErgoCSetConstruction,
2303                           "finish adding old regions to CSet",
2304                           ergo_format_reason("predicted time is too high")
2305                           ergo_format_ms("predicted time")
2306                           ergo_format_ms("remaining time")
2307                           ergo_format_region("old")
2308                           ergo_format_region("min"),
2309                           predicted_time_ms, time_remaining_ms,
2310                           old_cset_region_length(), min_old_cset_length);
2311             break;
2312           }
2313 
2314           // We'll add it anyway given that we haven't reached the
2315           // minimum number of old regions.
2316           expensive_region_num += 1;
2317         }
2318       } else {
2319         if (old_cset_region_length() >= min_old_cset_length) {
2320           // In the non-auto-tuning case, we'll finish adding regions
2321           // to the CSet if we reach the minimum.
2322           ergo_verbose2(ErgoCSetConstruction,
2323                         "finish adding old regions to CSet",
2324                         ergo_format_reason("old CSet region num reached min")
2325                         ergo_format_region("old")
2326                         ergo_format_region("min"),
2327                         old_cset_region_length(), min_old_cset_length);
2328           break;
2329         }
2330       }
2331 
2332       // We will add this region to the CSet.
2333       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2334       predicted_old_time_ms += predicted_time_ms;
2335       cset_chooser->pop(); // already have region via peek()
2336       _g1->old_set_remove(hr);
2337       add_old_region_to_cset(hr);
2338 
2339       hr = cset_chooser->peek();
2340     }
2341     if (hr == NULL) {
2342       ergo_verbose0(ErgoCSetConstruction,
2343                     "finish adding old regions to CSet",
2344                     ergo_format_reason("candidate old regions not available"));
2345     }
2346 
2347     if (expensive_region_num > 0) {
2348       // We print the information once here at the end, predicated on
2349       // whether we added any apparently expensive regions or not, to
2350       // avoid generating output per region.
2351       ergo_verbose4(ErgoCSetConstruction,
2352                     "added expensive regions to CSet",
2353                     ergo_format_reason("old CSet region num not reached min")
2354                     ergo_format_region("old")
2355                     ergo_format_region("expensive")
2356                     ergo_format_region("min")
2357                     ergo_format_ms("remaining time"),
2358                     old_cset_region_length(),
2359                     expensive_region_num,
2360                     min_old_cset_length,
2361                     time_remaining_ms);
2362     }
2363 
2364     cset_chooser->verify();
2365   }
2366 
2367   stop_incremental_cset_building();
2368 
2369   ergo_verbose3(ErgoCSetConstruction,
2370                 "finish choosing CSet",
2371                 ergo_format_region("old")
2372                 ergo_format_ms("predicted old region time")
2373                 ergo_format_ms("time remaining"),
2374                 old_cset_region_length(),
2375                 predicted_old_time_ms, time_remaining_ms);
2376 
2377   double non_young_end_time_sec = os::elapsedTime();
2378   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2379 }
2380 
2381 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2382   if(TraceYoungGenTime) {
2383     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2384   }
2385 }
2386 
2387 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2388   if(TraceYoungGenTime) {
2389     _all_yield_times_ms.add(yield_time_ms);
2390   }
2391 }
2392 
2393 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2394   if(TraceYoungGenTime) {
2395     _total.add(pause_time_ms);
2396     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2397     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2398     _parallel.add(phase_times->cur_collection_par_time_ms());
2399     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2400     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2401     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2402     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2403     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2404     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2405 
2406     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2407       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2408       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2409       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2410       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2411       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2412 
2413     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2414     _parallel_other.add(parallel_other_time);
2415     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2416   }
2417 }
2418 
2419 void TraceYoungGenTimeData::increment_young_collection_count() {
2420   if(TraceYoungGenTime) {
2421     ++_young_pause_num;
2422   }
2423 }
2424 
2425 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2426   if(TraceYoungGenTime) {
2427     ++_mixed_pause_num;
2428   }
2429 }
2430 
2431 void TraceYoungGenTimeData::print_summary(const char* str,
2432                                           const NumberSeq* seq) const {
2433   double sum = seq->sum();
2434   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2435                 str, sum / 1000.0, seq->avg());
2436 }
2437 
2438 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2439                                              const NumberSeq* seq) const {
2440   print_summary(str, seq);
2441   gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2442                 "(num", seq->num(), seq->sd(), seq->maximum());
2443 }
2444 
2445 void TraceYoungGenTimeData::print() const {
2446   if (!TraceYoungGenTime) {
2447     return;
2448   }
2449 
2450   gclog_or_tty->print_cr("ALL PAUSES");
2451   print_summary_sd("   Total", &_total);
2452   gclog_or_tty->cr();
2453   gclog_or_tty->cr();
2454   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2455   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2456   gclog_or_tty->cr();
2457 
2458   gclog_or_tty->print_cr("EVACUATION PAUSES");
2459 
2460   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2461     gclog_or_tty->print_cr("none");
2462   } else {
2463     print_summary_sd("   Evacuation Pauses", &_total);
2464     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2465     print_summary("      Parallel Time", &_parallel);
2466     print_summary("         Ext Root Scanning", &_ext_root_scan);
2467     print_summary("         SATB Filtering", &_satb_filtering);
2468     print_summary("         Update RS", &_update_rs);
2469     print_summary("         Scan RS", &_scan_rs);
2470     print_summary("         Object Copy", &_obj_copy);
2471     print_summary("         Termination", &_termination);
2472     print_summary("         Parallel Other", &_parallel_other);
2473     print_summary("      Clear CT", &_clear_ct);
2474     print_summary("      Other", &_other);
2475   }
2476   gclog_or_tty->cr();
2477 
2478   gclog_or_tty->print_cr("MISC");
2479   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2480   print_summary_sd("   Yields", &_all_yield_times_ms);
2481 }
2482 
2483 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2484   if (TraceOldGenTime) {
2485     _all_full_gc_times.add(full_gc_time_ms);
2486   }
2487 }
2488 
2489 void TraceOldGenTimeData::print() const {
2490   if (!TraceOldGenTime) {
2491     return;
2492   }
2493 
2494   if (_all_full_gc_times.num() > 0) {
2495     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2496       _all_full_gc_times.num(),
2497       _all_full_gc_times.sum() / 1000.0);
2498     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2499     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2500       _all_full_gc_times.sd(),
2501       _all_full_gc_times.maximum());
2502   }
2503 }
--- EOF ---