1 /*
   2  * Copyright (c) 2001, 2016, 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/concurrentMarkThread.inline.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1CollectorPolicy.hpp"
  30 #include "gc/g1/g1ConcurrentMark.hpp"
  31 #include "gc/g1/g1IHOPControl.hpp"
  32 #include "gc/g1/g1GCPhaseTimes.hpp"
  33 #include "gc/g1/heapRegion.inline.hpp"
  34 #include "gc/g1/heapRegionRemSet.hpp"
  35 #include "gc/shared/gcPolicyCounters.hpp"
  36 #include "runtime/arguments.hpp"
  37 #include "runtime/java.hpp"
  38 #include "runtime/mutexLocker.hpp"
  39 #include "utilities/debug.hpp"
  40 #include "utilities/pair.hpp"
  41 
  42 // Different defaults for different number of GC threads
  43 // They were chosen by running GCOld and SPECjbb on debris with different
  44 //   numbers of GC threads and choosing them based on the results
  45 
  46 // all the same
  47 static double rs_length_diff_defaults[] = {
  48   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
  49 };
  50 
  51 static double cost_per_card_ms_defaults[] = {
  52   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
  53 };
  54 
  55 // all the same
  56 static double young_cards_per_entry_ratio_defaults[] = {
  57   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
  58 };
  59 
  60 static double cost_per_entry_ms_defaults[] = {
  61   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
  62 };
  63 
  64 static double cost_per_byte_ms_defaults[] = {
  65   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
  66 };
  67 
  68 // these should be pretty consistent
  69 static double constant_other_time_ms_defaults[] = {
  70   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
  71 };
  72 
  73 
  74 static double young_other_cost_per_region_ms_defaults[] = {
  75   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
  76 };
  77 
  78 static double non_young_other_cost_per_region_ms_defaults[] = {
  79   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
  80 };
  81 
  82 G1CollectorPolicy::G1CollectorPolicy() :
  83   _predictor(G1ConfidencePercent / 100.0),
  84   _parallel_gc_threads(ParallelGCThreads),
  85 
  86   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  87   _stop_world_start(0.0),
  88 
  89   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  90   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  91 
  92   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  93   _prev_collection_pause_end_ms(0.0),
  94   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 105   _non_young_other_cost_per_region_ms_seq(
 106                                          new TruncatedSeq(TruncatedSeqLength)),
 107 
 108   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 109   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 110 
 111   _pause_time_target_ms((double) MaxGCPauseMillis),
 112 
 113   _recent_prev_end_times_for_all_gcs_sec(
 114                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 115 
 116   _recent_avg_pause_time_ratio(0.0),
 117   _rs_lengths_prediction(0),
 118   _max_survivor_regions(0),
 119 
 120   _eden_cset_region_length(0),
 121   _survivor_cset_region_length(0),
 122   _old_cset_region_length(0),
 123 
 124   _collection_set(NULL),
 125   _collection_set_bytes_used_before(0),
 126 
 127   // Incremental CSet attributes
 128   _inc_cset_build_state(Inactive),
 129   _inc_cset_head(NULL),
 130   _inc_cset_tail(NULL),
 131   _inc_cset_bytes_used_before(0),
 132   _inc_cset_max_finger(NULL),
 133   _inc_cset_recorded_rs_lengths(0),
 134   _inc_cset_recorded_rs_lengths_diffs(0),
 135   _inc_cset_predicted_elapsed_time_ms(0.0),
 136   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 137 
 138   // add here any more surv rate groups
 139   _recorded_survivor_regions(0),
 140   _recorded_survivor_head(NULL),
 141   _recorded_survivor_tail(NULL),
 142   _survivors_age_table(true),
 143 
 144   _gc_overhead_perc(0.0),
 145 
 146   _bytes_allocated_in_old_since_last_gc(0),
 147   _ihop_control(NULL),
 148   _initial_mark_to_mixed() {
 149 
 150   // SurvRateGroups below must be initialized after the predictor because they
 151   // indirectly use it through this object passed to their constructor.
 152   _short_lived_surv_rate_group =
 153     new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
 154   _survivor_surv_rate_group =
 155     new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
 156 
 157   // Set up the region size and associated fields. Given that the
 158   // policy is created before the heap, we have to set this up here,
 159   // so it's done as soon as possible.
 160 
 161   // It would have been natural to pass initial_heap_byte_size() and
 162   // max_heap_byte_size() to setup_heap_region_size() but those have
 163   // not been set up at this point since they should be aligned with
 164   // the region size. So, there is a circular dependency here. We base
 165   // the region size on the heap size, but the heap size should be
 166   // aligned with the region size. To get around this we use the
 167   // unaligned values for the heap.
 168   HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
 169   HeapRegionRemSet::setup_remset_size();
 170 
 171   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 172   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 173   clear_ratio_check_data();
 174 
 175   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 176 
 177   int index = MIN2(_parallel_gc_threads - 1, 7);
 178 
 179   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 180   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 181   _cost_scan_hcc_seq->add(0.0);
 182   _young_cards_per_entry_ratio_seq->add(
 183                                   young_cards_per_entry_ratio_defaults[index]);
 184   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 185   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 186   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 187   _young_other_cost_per_region_ms_seq->add(
 188                                young_other_cost_per_region_ms_defaults[index]);
 189   _non_young_other_cost_per_region_ms_seq->add(
 190                            non_young_other_cost_per_region_ms_defaults[index]);
 191 
 192   // Below, we might need to calculate the pause time target based on
 193   // the pause interval. When we do so we are going to give G1 maximum
 194   // flexibility and allow it to do pauses when it needs to. So, we'll
 195   // arrange that the pause interval to be pause time target + 1 to
 196   // ensure that a) the pause time target is maximized with respect to
 197   // the pause interval and b) we maintain the invariant that pause
 198   // time target < pause interval. If the user does not want this
 199   // maximum flexibility, they will have to set the pause interval
 200   // explicitly.
 201 
 202   // First make sure that, if either parameter is set, its value is
 203   // reasonable.
 204   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 205     if (MaxGCPauseMillis < 1) {
 206       vm_exit_during_initialization("MaxGCPauseMillis should be "
 207                                     "greater than 0");
 208     }
 209   }
 210   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 211     if (GCPauseIntervalMillis < 1) {
 212       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 213                                     "greater than 0");
 214     }
 215   }
 216 
 217   // Then, if the pause time target parameter was not set, set it to
 218   // the default value.
 219   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 220     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 221       // The default pause time target in G1 is 200ms
 222       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 223     } else {
 224       // We do not allow the pause interval to be set without the
 225       // pause time target
 226       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 227                                     "without setting MaxGCPauseMillis");
 228     }
 229   }
 230 
 231   // Then, if the interval parameter was not set, set it according to
 232   // the pause time target (this will also deal with the case when the
 233   // pause time target is the default value).
 234   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 235     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 236   }
 237 
 238   // Finally, make sure that the two parameters are consistent.
 239   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 240     char buffer[256];
 241     jio_snprintf(buffer, 256,
 242                  "MaxGCPauseMillis (%u) should be less than "
 243                  "GCPauseIntervalMillis (%u)",
 244                  MaxGCPauseMillis, GCPauseIntervalMillis);
 245     vm_exit_during_initialization(buffer);
 246   }
 247 
 248   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 249   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 250   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 251 
 252   // start conservatively (around 50ms is about right)
 253   _concurrent_mark_remark_times_ms->add(0.05);
 254   _concurrent_mark_cleanup_times_ms->add(0.20);
 255   _tenuring_threshold = MaxTenuringThreshold;
 256 
 257   assert(GCTimeRatio > 0,
 258          "we should have set it to a default value set_g1_gc_flags() "
 259          "if a user set it to 0");
 260   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 261 
 262   uintx reserve_perc = G1ReservePercent;
 263   // Put an artificial ceiling on this so that it's not set to a silly value.
 264   if (reserve_perc > 50) {
 265     reserve_perc = 50;
 266     warning("G1ReservePercent is set to a value that is too large, "
 267             "it's been updated to " UINTX_FORMAT, reserve_perc);
 268   }
 269   _reserve_factor = (double) reserve_perc / 100.0;
 270   // This will be set when the heap is expanded
 271   // for the first time during initialization.
 272   _reserve_regions = 0;
 273 
 274   _cset_chooser = new CollectionSetChooser();
 275 }
 276 
 277 G1CollectorPolicy::~G1CollectorPolicy() {
 278   delete _ihop_control;
 279 }
 280 
 281 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
 282   return _predictor.get_new_prediction(seq);
 283 }
 284 
 285 size_t G1CollectorPolicy::get_new_size_prediction(TruncatedSeq const* seq) const {
 286   return (size_t)get_new_prediction(seq);
 287 }
 288 
 289 void G1CollectorPolicy::initialize_alignments() {
 290   _space_alignment = HeapRegion::GrainBytes;
 291   size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
 292   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
 293   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 294 }
 295 
 296 void G1CollectorPolicy::initialize_flags() {
 297   if (G1HeapRegionSize != HeapRegion::GrainBytes) {
 298     FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
 299   }
 300 
 301   if (SurvivorRatio < 1) {
 302     vm_exit_during_initialization("Invalid survivor ratio specified");
 303   }
 304   CollectorPolicy::initialize_flags();
 305   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 306 }
 307 
 308 void G1CollectorPolicy::post_heap_initialize() {
 309   uintx max_regions = G1CollectedHeap::heap()->max_regions();
 310   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
 311   if (max_young_size != MaxNewSize) {
 312     FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
 313   }
 314 
 315   _ihop_control = create_ihop_control();
 316 }
 317 
 318 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
 319 
 320 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
 321         _min_desired_young_length(0), _max_desired_young_length(0) {
 322   if (FLAG_IS_CMDLINE(NewRatio)) {
 323     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 324       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 325     } else {
 326       _sizer_kind = SizerNewRatio;
 327       _adaptive_size = false;
 328       return;
 329     }
 330   }
 331 
 332   if (NewSize > MaxNewSize) {
 333     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 334       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 335               "A new max generation size of " SIZE_FORMAT "k will be used.",
 336               NewSize/K, MaxNewSize/K, NewSize/K);
 337     }
 338     MaxNewSize = NewSize;
 339   }
 340 
 341   if (FLAG_IS_CMDLINE(NewSize)) {
 342     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 343                                      1U);
 344     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 345       _max_desired_young_length =
 346                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 347                                   1U);
 348       _sizer_kind = SizerMaxAndNewSize;
 349       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 350     } else {
 351       _sizer_kind = SizerNewSizeOnly;
 352     }
 353   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 354     _max_desired_young_length =
 355                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 356                                   1U);
 357     _sizer_kind = SizerMaxNewSizeOnly;
 358   }
 359 }
 360 
 361 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 362   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 363   return MAX2(1U, default_value);
 364 }
 365 
 366 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 367   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 368   return MAX2(1U, default_value);
 369 }
 370 
 371 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
 372   assert(number_of_heap_regions > 0, "Heap must be initialized");
 373 
 374   switch (_sizer_kind) {
 375     case SizerDefaults:
 376       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 377       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 378       break;
 379     case SizerNewSizeOnly:
 380       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 381       *max_young_length = MAX2(*min_young_length, *max_young_length);
 382       break;
 383     case SizerMaxNewSizeOnly:
 384       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 385       *min_young_length = MIN2(*min_young_length, *max_young_length);
 386       break;
 387     case SizerMaxAndNewSize:
 388       // Do nothing. Values set on the command line, don't update them at runtime.
 389       break;
 390     case SizerNewRatio:
 391       *min_young_length = number_of_heap_regions / (NewRatio + 1);
 392       *max_young_length = *min_young_length;
 393       break;
 394     default:
 395       ShouldNotReachHere();
 396   }
 397 
 398   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
 399 }
 400 
 401 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
 402   // We need to pass the desired values because recalculation may not update these
 403   // values in some cases.
 404   uint temp = _min_desired_young_length;
 405   uint result = _max_desired_young_length;
 406   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
 407   return result;
 408 }
 409 
 410 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 411   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
 412           &_max_desired_young_length);
 413 }
 414 
 415 void G1CollectorPolicy::init() {
 416   // Set aside an initial future to_space.
 417   _g1 = G1CollectedHeap::heap();
 418 
 419   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 420 
 421   initialize_gc_policy_counters();
 422 
 423   if (adaptive_young_list_length()) {
 424     _young_list_fixed_length = 0;
 425   } else {
 426     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 427   }
 428   _free_regions_at_end_of_collection = _g1->num_free_regions();
 429 
 430   update_young_list_max_and_target_length();
 431   // We may immediately start allocating regions and placing them on the
 432   // collection set list. Initialize the per-collection set info
 433   start_incremental_cset_building();
 434 }
 435 
 436 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
 437   phase_times()->note_gc_start(num_active_workers);
 438 }
 439 
 440 // Create the jstat counters for the policy.
 441 void G1CollectorPolicy::initialize_gc_policy_counters() {
 442   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 443 }
 444 
 445 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 446                                          double base_time_ms,
 447                                          uint base_free_regions,
 448                                          double target_pause_time_ms) const {
 449   if (young_length >= base_free_regions) {
 450     // end condition 1: not enough space for the young regions
 451     return false;
 452   }
 453 
 454   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 455   size_t bytes_to_copy =
 456                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 457   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 458   double young_other_time_ms = predict_young_other_time_ms(young_length);
 459   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 460   if (pause_time_ms > target_pause_time_ms) {
 461     // end condition 2: prediction is over the target pause time
 462     return false;
 463   }
 464 
 465   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 466 
 467   // When copying, we will likely need more bytes free than is live in the region.
 468   // Add some safety margin to factor in the confidence of our guess, and the
 469   // natural expected waste.
 470   // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 471   // of the calculation: the lower the confidence, the more headroom.
 472   // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 473   // copying due to anticipated waste in the PLABs.
 474   double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 475   size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
 476 
 477   if (expected_bytes_to_copy > free_bytes) {
 478     // end condition 3: out-of-space
 479     return false;
 480   }
 481 
 482   // success!
 483   return true;
 484 }
 485 
 486 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 487   // re-calculate the necessary reserve
 488   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 489   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 490   // smaller than 1.0) we'll get 1.
 491   _reserve_regions = (uint) ceil(reserve_regions_d);
 492 
 493   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 494 }
 495 
 496 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 497                                                        uint base_min_length) const {
 498   uint desired_min_length = 0;
 499   if (adaptive_young_list_length()) {
 500     if (_alloc_rate_ms_seq->num() > 3) {
 501       double now_sec = os::elapsedTime();
 502       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 503       double alloc_rate_ms = predict_alloc_rate_ms();
 504       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 505     } else {
 506       // otherwise we don't have enough info to make the prediction
 507     }
 508   }
 509   desired_min_length += base_min_length;
 510   // make sure we don't go below any user-defined minimum bound
 511   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 512 }
 513 
 514 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
 515   // Here, we might want to also take into account any additional
 516   // constraints (i.e., user-defined minimum bound). Currently, we
 517   // effectively don't set this bound.
 518   return _young_gen_sizer->max_desired_young_length();
 519 }
 520 
 521 uint G1CollectorPolicy::update_young_list_max_and_target_length() {
 522   return update_young_list_max_and_target_length(get_new_size_prediction(_rs_lengths_seq));
 523 }
 524 
 525 uint G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 526   uint unbounded_target_length = update_young_list_target_length(rs_lengths);
 527   update_max_gc_locker_expansion();
 528   return unbounded_target_length;
 529 }
 530 
 531 uint G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 532   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
 533   _young_list_target_length = young_lengths.first;
 534   return young_lengths.second;
 535 }
 536 
 537 G1CollectorPolicy::YoungTargetLengths G1CollectorPolicy::young_list_target_lengths(size_t rs_lengths) const {
 538   YoungTargetLengths result;
 539 
 540   // Calculate the absolute and desired min bounds first.
 541 
 542   // This is how many young regions we already have (currently: the survivors).
 543   uint base_min_length = recorded_survivor_regions();
 544   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 545   // This is the absolute minimum young length. Ensure that we
 546   // will at least have one eden region available for allocation.
 547   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 548   // If we shrank the young list target it should not shrink below the current size.
 549   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 550   // Calculate the absolute and desired max bounds.
 551 
 552   uint desired_max_length = calculate_young_list_desired_max_length();
 553 
 554   uint young_list_target_length = 0;
 555   if (adaptive_young_list_length()) {
 556     if (collector_state()->gcs_are_young()) {
 557       young_list_target_length =
 558                         calculate_young_list_target_length(rs_lengths,
 559                                                            base_min_length,
 560                                                            desired_min_length,
 561                                                            desired_max_length);
 562     } else {
 563       // Don't calculate anything and let the code below bound it to
 564       // the desired_min_length, i.e., do the next GC as soon as
 565       // possible to maximize how many old regions we can add to it.
 566     }
 567   } else {
 568     // The user asked for a fixed young gen so we'll fix the young gen
 569     // whether the next GC is young or mixed.
 570     young_list_target_length = _young_list_fixed_length;
 571   }
 572 
 573   result.second = young_list_target_length;
 574 
 575   // We will try our best not to "eat" into the reserve.
 576   uint absolute_max_length = 0;
 577   if (_free_regions_at_end_of_collection > _reserve_regions) {
 578     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 579   }
 580   if (desired_max_length > absolute_max_length) {
 581     desired_max_length = absolute_max_length;
 582   }
 583 
 584   // Make sure we don't go over the desired max length, nor under the
 585   // desired min length. In case they clash, desired_min_length wins
 586   // which is why that test is second.
 587   if (young_list_target_length > desired_max_length) {
 588     young_list_target_length = desired_max_length;
 589   }
 590   if (young_list_target_length < desired_min_length) {
 591     young_list_target_length = desired_min_length;
 592   }
 593 
 594   assert(young_list_target_length > recorded_survivor_regions(),
 595          "we should be able to allocate at least one eden region");
 596   assert(young_list_target_length >= absolute_min_length, "post-condition");
 597 
 598   result.first = young_list_target_length;
 599   return result;
 600 }
 601 
 602 uint
 603 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 604                                                      uint base_min_length,
 605                                                      uint desired_min_length,
 606                                                      uint desired_max_length) const {
 607   assert(adaptive_young_list_length(), "pre-condition");
 608   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 609 
 610   // In case some edge-condition makes the desired max length too small...
 611   if (desired_max_length <= desired_min_length) {
 612     return desired_min_length;
 613   }
 614 
 615   // We'll adjust min_young_length and max_young_length not to include
 616   // the already allocated young regions (i.e., so they reflect the
 617   // min and max eden regions we'll allocate). The base_min_length
 618   // will be reflected in the predictions by the
 619   // survivor_regions_evac_time prediction.
 620   assert(desired_min_length > base_min_length, "invariant");
 621   uint min_young_length = desired_min_length - base_min_length;
 622   assert(desired_max_length > base_min_length, "invariant");
 623   uint max_young_length = desired_max_length - base_min_length;
 624 
 625   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 626   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 627   size_t pending_cards = get_new_size_prediction(_pending_cards_seq);
 628   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 629   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 630   double base_time_ms =
 631     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 632     survivor_regions_evac_time;
 633   uint available_free_regions = _free_regions_at_end_of_collection;
 634   uint base_free_regions = 0;
 635   if (available_free_regions > _reserve_regions) {
 636     base_free_regions = available_free_regions - _reserve_regions;
 637   }
 638 
 639   // Here, we will make sure that the shortest young length that
 640   // makes sense fits within the target pause time.
 641 
 642   if (predict_will_fit(min_young_length, base_time_ms,
 643                        base_free_regions, target_pause_time_ms)) {
 644     // The shortest young length will fit into the target pause time;
 645     // we'll now check whether the absolute maximum number of young
 646     // regions will fit in the target pause time. If not, we'll do
 647     // a binary search between min_young_length and max_young_length.
 648     if (predict_will_fit(max_young_length, base_time_ms,
 649                          base_free_regions, target_pause_time_ms)) {
 650       // The maximum young length will fit into the target pause time.
 651       // We are done so set min young length to the maximum length (as
 652       // the result is assumed to be returned in min_young_length).
 653       min_young_length = max_young_length;
 654     } else {
 655       // The maximum possible number of young regions will not fit within
 656       // the target pause time so we'll search for the optimal
 657       // length. The loop invariants are:
 658       //
 659       // min_young_length < max_young_length
 660       // min_young_length is known to fit into the target pause time
 661       // max_young_length is known not to fit into the target pause time
 662       //
 663       // Going into the loop we know the above hold as we've just
 664       // checked them. Every time around the loop we check whether
 665       // the middle value between min_young_length and
 666       // max_young_length fits into the target pause time. If it
 667       // does, it becomes the new min. If it doesn't, it becomes
 668       // the new max. This way we maintain the loop invariants.
 669 
 670       assert(min_young_length < max_young_length, "invariant");
 671       uint diff = (max_young_length - min_young_length) / 2;
 672       while (diff > 0) {
 673         uint young_length = min_young_length + diff;
 674         if (predict_will_fit(young_length, base_time_ms,
 675                              base_free_regions, target_pause_time_ms)) {
 676           min_young_length = young_length;
 677         } else {
 678           max_young_length = young_length;
 679         }
 680         assert(min_young_length <  max_young_length, "invariant");
 681         diff = (max_young_length - min_young_length) / 2;
 682       }
 683       // The results is min_young_length which, according to the
 684       // loop invariants, should fit within the target pause time.
 685 
 686       // These are the post-conditions of the binary search above:
 687       assert(min_young_length < max_young_length,
 688              "otherwise we should have discovered that max_young_length "
 689              "fits into the pause target and not done the binary search");
 690       assert(predict_will_fit(min_young_length, base_time_ms,
 691                               base_free_regions, target_pause_time_ms),
 692              "min_young_length, the result of the binary search, should "
 693              "fit into the pause target");
 694       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 695                                base_free_regions, target_pause_time_ms),
 696              "min_young_length, the result of the binary search, should be "
 697              "optimal, so no larger length should fit into the pause target");
 698     }
 699   } else {
 700     // Even the minimum length doesn't fit into the pause time
 701     // target, return it as the result nevertheless.
 702   }
 703   return base_min_length + min_young_length;
 704 }
 705 
 706 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
 707   double survivor_regions_evac_time = 0.0;
 708   for (HeapRegion * r = _recorded_survivor_head;
 709        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 710        r = r->get_next_young_region()) {
 711     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 712   }
 713   return survivor_regions_evac_time;
 714 }
 715 
 716 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 717   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 718 
 719   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 720   if (rs_lengths > _rs_lengths_prediction) {
 721     // add 10% to avoid having to recalculate often
 722     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 723     update_rs_lengths_prediction(rs_lengths_prediction);
 724 
 725     update_young_list_max_and_target_length(rs_lengths_prediction);
 726   }
 727 }
 728 
 729 void G1CollectorPolicy::update_rs_lengths_prediction() {
 730   update_rs_lengths_prediction(get_new_size_prediction(_rs_lengths_seq));
 731 }
 732 
 733 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
 734   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 735     _rs_lengths_prediction = prediction;
 736   }
 737 }
 738 
 739 #ifndef PRODUCT
 740 bool G1CollectorPolicy::verify_young_ages() {
 741   HeapRegion* head = _g1->young_list()->first_region();
 742   return
 743     verify_young_ages(head, _short_lived_surv_rate_group);
 744   // also call verify_young_ages on any additional surv rate groups
 745 }
 746 
 747 bool
 748 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 749                                      SurvRateGroup *surv_rate_group) {
 750   guarantee( surv_rate_group != NULL, "pre-condition" );
 751 
 752   const char* name = surv_rate_group->name();
 753   bool ret = true;
 754   int prev_age = -1;
 755 
 756   for (HeapRegion* curr = head;
 757        curr != NULL;
 758        curr = curr->get_next_young_region()) {
 759     SurvRateGroup* group = curr->surv_rate_group();
 760     if (group == NULL && !curr->is_survivor()) {
 761       log_info(gc, verify)("## %s: encountered NULL surv_rate_group", name);
 762       ret = false;
 763     }
 764 
 765     if (surv_rate_group == group) {
 766       int age = curr->age_in_surv_rate_group();
 767 
 768       if (age < 0) {
 769         log_info(gc, verify)("## %s: encountered negative age", name);
 770         ret = false;
 771       }
 772 
 773       if (age <= prev_age) {
 774         log_info(gc, verify)("## %s: region ages are not strictly increasing (%d, %d)", name, age, prev_age);
 775         ret = false;
 776       }
 777       prev_age = age;
 778     }
 779   }
 780 
 781   return ret;
 782 }
 783 #endif // PRODUCT
 784 
 785 void G1CollectorPolicy::record_full_collection_start() {
 786   _full_collection_start_sec = os::elapsedTime();
 787   // Release the future to-space so that it is available for compaction into.
 788   collector_state()->set_full_collection(true);
 789 }
 790 
 791 void G1CollectorPolicy::record_full_collection_end() {
 792   // Consider this like a collection pause for the purposes of allocation
 793   // since last pause.
 794   double end_sec = os::elapsedTime();
 795   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 796   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 797 
 798   _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
 799 
 800   update_recent_gc_times(end_sec, full_gc_time_ms);
 801 
 802   collector_state()->set_full_collection(false);
 803 
 804   // "Nuke" the heuristics that control the young/mixed GC
 805   // transitions and make sure we start with young GCs after the Full GC.
 806   collector_state()->set_gcs_are_young(true);
 807   collector_state()->set_last_young_gc(false);
 808   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 809   collector_state()->set_during_initial_mark_pause(false);
 810   collector_state()->set_in_marking_window(false);
 811   collector_state()->set_in_marking_window_im(false);
 812 
 813   _short_lived_surv_rate_group->start_adding_regions();
 814   // also call this on any additional surv rate groups
 815 
 816   record_survivor_regions(0, NULL, NULL);
 817 
 818   _free_regions_at_end_of_collection = _g1->num_free_regions();
 819   // Reset survivors SurvRateGroup.
 820   _survivor_surv_rate_group->reset();
 821   update_young_list_max_and_target_length();
 822   update_rs_lengths_prediction();
 823   cset_chooser()->clear();
 824 
 825   _bytes_allocated_in_old_since_last_gc = 0;
 826 
 827   record_pause(FullGC, _full_collection_start_sec, end_sec);
 828 }
 829 
 830 void G1CollectorPolicy::record_stop_world_start() {
 831   _stop_world_start = os::elapsedTime();
 832 }
 833 
 834 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
 835   // We only need to do this here as the policy will only be applied
 836   // to the GC we're about to start. so, no point is calculating this
 837   // every time we calculate / recalculate the target young length.
 838   update_survivors_policy();
 839 
 840   assert(_g1->used() == _g1->recalculate_used(),
 841          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 842          _g1->used(), _g1->recalculate_used());
 843 
 844   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 845   _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
 846   _stop_world_start = 0.0;
 847 
 848   phase_times()->record_cur_collection_start_sec(start_time_sec);
 849   _pending_cards = _g1->pending_card_num();
 850 
 851   _collection_set_bytes_used_before = 0;
 852   _bytes_copied_during_gc = 0;
 853 
 854   collector_state()->set_last_gc_was_young(false);
 855 
 856   // do that for any other surv rate groups
 857   _short_lived_surv_rate_group->stop_adding_regions();
 858   _survivors_age_table.clear();
 859 
 860   assert( verify_young_ages(), "region age verification" );
 861 }
 862 
 863 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 864                                                    mark_init_elapsed_time_ms) {
 865   collector_state()->set_during_marking(true);
 866   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 867   collector_state()->set_during_initial_mark_pause(false);
 868 }
 869 
 870 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 871   _mark_remark_start_sec = os::elapsedTime();
 872   collector_state()->set_during_marking(false);
 873 }
 874 
 875 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 876   double end_time_sec = os::elapsedTime();
 877   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 878   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 879   _prev_collection_pause_end_ms += elapsed_time_ms;
 880 
 881   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 882 }
 883 
 884 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 885   _mark_cleanup_start_sec = os::elapsedTime();
 886 }
 887 
 888 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 889   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 890                                                               "skip last young-only gc");
 891   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 892   // We skip the marking phase.
 893   if (!should_continue_with_reclaim) {
 894     abort_time_to_mixed_tracking();
 895   }
 896   collector_state()->set_in_marking_window(false);
 897 }
 898 
 899 void G1CollectorPolicy::record_concurrent_pause() {
 900   if (_stop_world_start > 0.0) {
 901     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 902     _trace_young_gen_time_data.record_yield_time(yield_ms);
 903   }
 904 }
 905 
 906 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 907   return phase_times()->average_time_ms(phase);
 908 }
 909 
 910 double G1CollectorPolicy::young_other_time_ms() const {
 911   return phase_times()->young_cset_choice_time_ms() +
 912          phase_times()->young_free_cset_time_ms();
 913 }
 914 
 915 double G1CollectorPolicy::non_young_other_time_ms() const {
 916   return phase_times()->non_young_cset_choice_time_ms() +
 917          phase_times()->non_young_free_cset_time_ms();
 918 
 919 }
 920 
 921 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
 922   return pause_time_ms -
 923          average_time_ms(G1GCPhaseTimes::UpdateRS) -
 924          average_time_ms(G1GCPhaseTimes::ScanRS) -
 925          average_time_ms(G1GCPhaseTimes::ObjCopy) -
 926          average_time_ms(G1GCPhaseTimes::Termination);
 927 }
 928 
 929 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
 930   return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
 931 }
 932 
 933 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
 934   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 935 }
 936 
 937 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 938   if (about_to_start_mixed_phase()) {
 939     return false;
 940   }
 941 
 942   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 943 
 944   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 945   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 946   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 947 
 948   bool result = false;
 949   if (marking_request_bytes > marking_initiating_used_threshold) {
 950     result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
 951     log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
 952                               result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
 953                               cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
 954   }
 955 
 956   return result;
 957 }
 958 
 959 // Anything below that is considered to be zero
 960 #define MIN_TIMER_GRANULARITY 0.0000001
 961 
 962 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
 963   double end_time_sec = os::elapsedTime();
 964 
 965   size_t cur_used_bytes = _g1->used();
 966   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 967   bool last_pause_included_initial_mark = false;
 968   bool update_stats = !_g1->evacuation_failed();
 969 
 970   NOT_PRODUCT(_short_lived_surv_rate_group->print());
 971 
 972   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
 973 
 974   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
 975   if (last_pause_included_initial_mark) {
 976     record_concurrent_mark_init_end(0.0);
 977   } else {
 978     maybe_start_marking();
 979   }
 980 
 981   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
 982   if (app_time_ms < MIN_TIMER_GRANULARITY) {
 983     // This usually happens due to the timer not having the required
 984     // granularity. Some Linuxes are the usual culprits.
 985     // We'll just set it to something (arbitrarily) small.
 986     app_time_ms = 1.0;
 987   }
 988 
 989   if (update_stats) {
 990     _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
 991     // We maintain the invariant that all objects allocated by mutator
 992     // threads will be allocated out of eden regions. So, we can use
 993     // the eden region number allocated since the previous GC to
 994     // calculate the application's allocate rate. The only exception
 995     // to that is humongous objects that are allocated separately. But
 996     // given that humongous object allocations do not really affect
 997     // either the pause's duration nor when the next pause will take
 998     // place we can safely ignore them here.
 999     uint regions_allocated = eden_cset_region_length();
1000     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1001     _alloc_rate_ms_seq->add(alloc_rate_ms);
1002 
1003     double interval_ms =
1004       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1005     update_recent_gc_times(end_time_sec, pause_time_ms);
1006     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1007     if (recent_avg_pause_time_ratio() < 0.0 ||
1008         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1009       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1010       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1011       if (_recent_avg_pause_time_ratio < 0.0) {
1012         _recent_avg_pause_time_ratio = 0.0;
1013       } else {
1014         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1015         _recent_avg_pause_time_ratio = 1.0;
1016       }
1017     }
1018 
1019     // Compute the ratio of just this last pause time to the entire time range stored
1020     // in the vectors. Comparing this pause to the entire range, rather than only the
1021     // most recent interval, has the effect of smoothing over a possible transient 'burst'
1022     // of more frequent pauses that don't really reflect a change in heap occupancy.
1023     // This reduces the likelihood of a needless heap expansion being triggered.
1024     _last_pause_time_ratio =
1025       (pause_time_ms * _recent_prev_end_times_for_all_gcs_sec->num()) / interval_ms;
1026   }
1027 
1028   bool new_in_marking_window = collector_state()->in_marking_window();
1029   bool new_in_marking_window_im = false;
1030   if (last_pause_included_initial_mark) {
1031     new_in_marking_window = true;
1032     new_in_marking_window_im = true;
1033   }
1034 
1035   if (collector_state()->last_young_gc()) {
1036     // This is supposed to to be the "last young GC" before we start
1037     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1038     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1039 
1040     if (next_gc_should_be_mixed("start mixed GCs",
1041                                 "do not start mixed GCs")) {
1042       collector_state()->set_gcs_are_young(false);
1043     } else {
1044       // We aborted the mixed GC phase early.
1045       abort_time_to_mixed_tracking();
1046     }
1047 
1048     collector_state()->set_last_young_gc(false);
1049   }
1050 
1051   if (!collector_state()->last_gc_was_young()) {
1052     // This is a mixed GC. Here we decide whether to continue doing
1053     // mixed GCs or not.
1054     if (!next_gc_should_be_mixed("continue mixed GCs",
1055                                  "do not continue mixed GCs")) {
1056       collector_state()->set_gcs_are_young(true);
1057 
1058       maybe_start_marking();
1059     }
1060   }
1061 
1062   _short_lived_surv_rate_group->start_adding_regions();
1063   // Do that for any other surv rate groups
1064 
1065   if (update_stats) {
1066     double cost_per_card_ms = 0.0;
1067     double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1068     if (_pending_cards > 0) {
1069       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1070       _cost_per_card_ms_seq->add(cost_per_card_ms);
1071     }
1072     _cost_scan_hcc_seq->add(cost_scan_hcc);
1073 
1074     double cost_per_entry_ms = 0.0;
1075     if (cards_scanned > 10) {
1076       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1077       if (collector_state()->last_gc_was_young()) {
1078         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1079       } else {
1080         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1081       }
1082     }
1083 
1084     if (_max_rs_lengths > 0) {
1085       double cards_per_entry_ratio =
1086         (double) cards_scanned / (double) _max_rs_lengths;
1087       if (collector_state()->last_gc_was_young()) {
1088         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1089       } else {
1090         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1091       }
1092     }
1093 
1094     // This is defensive. For a while _max_rs_lengths could get
1095     // smaller than _recorded_rs_lengths which was causing
1096     // rs_length_diff to get very large and mess up the RSet length
1097     // predictions. The reason was unsafe concurrent updates to the
1098     // _inc_cset_recorded_rs_lengths field which the code below guards
1099     // against (see CR 7118202). This bug has now been fixed (see CR
1100     // 7119027). However, I'm still worried that
1101     // _inc_cset_recorded_rs_lengths might still end up somewhat
1102     // inaccurate. The concurrent refinement thread calculates an
1103     // RSet's length concurrently with other CR threads updating it
1104     // which might cause it to calculate the length incorrectly (if,
1105     // say, it's in mid-coarsening). So I'll leave in the defensive
1106     // conditional below just in case.
1107     size_t rs_length_diff = 0;
1108     if (_max_rs_lengths > _recorded_rs_lengths) {
1109       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1110     }
1111     _rs_length_diff_seq->add((double) rs_length_diff);
1112 
1113     size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
1114     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1115     double cost_per_byte_ms = 0.0;
1116 
1117     if (copied_bytes > 0) {
1118       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1119       if (collector_state()->in_marking_window()) {
1120         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1121       } else {
1122         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1123       }
1124     }
1125 
1126     if (young_cset_region_length() > 0) {
1127       _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1128                                                young_cset_region_length());
1129     }
1130 
1131     if (old_cset_region_length() > 0) {
1132       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1133                                                    old_cset_region_length());
1134     }
1135 
1136     _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1137 
1138     _pending_cards_seq->add((double) _pending_cards);
1139     _rs_lengths_seq->add((double) _max_rs_lengths);
1140   }
1141 
1142   collector_state()->set_in_marking_window(new_in_marking_window);
1143   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1144   _free_regions_at_end_of_collection = _g1->num_free_regions();
1145   // IHOP control wants to know the expected young gen length if it were not
1146   // restrained by the heap reserve. Using the actual length would make the
1147   // prediction too small and the limit the young gen every time we get to the
1148   // predicted target occupancy.
1149   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
1150   update_rs_lengths_prediction();
1151 
1152   update_ihop_prediction(app_time_ms / 1000.0,
1153                          _bytes_allocated_in_old_since_last_gc,
1154                          last_unrestrained_young_length * HeapRegion::GrainBytes);
1155   _bytes_allocated_in_old_since_last_gc = 0;
1156 
1157   _ihop_control->send_trace_event(_g1->gc_tracer_stw());
1158 
1159   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1160   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1161 
1162   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1163 
1164   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1165     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
1166                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
1167                                 update_rs_time_goal_ms, scan_hcc_time_ms);
1168 
1169     update_rs_time_goal_ms = 0;
1170   } else {
1171     update_rs_time_goal_ms -= scan_hcc_time_ms;
1172   }
1173   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1174                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1175                                update_rs_time_goal_ms);
1176 
1177   cset_chooser()->verify();
1178 }
1179 
1180 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1181   if (G1UseAdaptiveIHOP) {
1182     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1183                                      G1CollectedHeap::heap()->max_capacity(),
1184                                      &_predictor,
1185                                      G1ReservePercent,
1186                                      G1HeapWastePercent);
1187   } else {
1188     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1189                                    G1CollectedHeap::heap()->max_capacity());
1190   }
1191 }
1192 
1193 void G1CollectorPolicy::update_ihop_prediction(double mutator_time_s,
1194                                                size_t mutator_alloc_bytes,
1195                                                size_t young_gen_size) {
1196   // Always try to update IHOP prediction. Even evacuation failures give information
1197   // about e.g. whether to start IHOP earlier next time.
1198 
1199   // Avoid using really small application times that might create samples with
1200   // very high or very low values. They may be caused by e.g. back-to-back gcs.
1201   double const min_valid_time = 1e-6;
1202 
1203   bool report = false;
1204 
1205   double marking_to_mixed_time = -1.0;
1206   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1207     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1208     assert(marking_to_mixed_time > 0.0,
1209            "Initial mark to mixed time must be larger than zero but is %.3f",
1210            marking_to_mixed_time);
1211     if (marking_to_mixed_time > min_valid_time) {
1212       _ihop_control->update_marking_length(marking_to_mixed_time);
1213       report = true;
1214     }
1215   }
1216 
1217   // As an approximation for the young gc promotion rates during marking we use
1218   // all of them. In many applications there are only a few if any young gcs during
1219   // marking, which makes any prediction useless. This increases the accuracy of the
1220   // prediction.
1221   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1222     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1223     report = true;
1224   }
1225 
1226   if (report) {
1227     report_ihop_statistics();
1228   }
1229 }
1230 
1231 void G1CollectorPolicy::report_ihop_statistics() {
1232   _ihop_control->print();
1233 }
1234 
1235 void G1CollectorPolicy::print_phases() {
1236   phase_times()->print();
1237 }
1238 
1239 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1240                                                      double update_rs_processed_buffers,
1241                                                      double goal_ms) {
1242   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1243   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1244 
1245   if (G1UseAdaptiveConcRefinement) {
1246     const int k_gy = 3, k_gr = 6;
1247     const double inc_k = 1.1, dec_k = 0.9;
1248 
1249     int g = cg1r->green_zone();
1250     if (update_rs_time > goal_ms) {
1251       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1252     } else {
1253       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1254         g = (int)MAX2(g * inc_k, g + 1.0);
1255       }
1256     }
1257     // Change the refinement threads params
1258     cg1r->set_green_zone(g);
1259     cg1r->set_yellow_zone(g * k_gy);
1260     cg1r->set_red_zone(g * k_gr);
1261     cg1r->reinitialize_threads();
1262 
1263     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1264     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1265                                     cg1r->yellow_zone());
1266     // Change the barrier params
1267     dcqs.set_process_completed_threshold(processing_threshold);
1268     dcqs.set_max_completed_queue(cg1r->red_zone());
1269   }
1270 
1271   int curr_queue_size = dcqs.completed_buffers_num();
1272   if (curr_queue_size >= cg1r->yellow_zone()) {
1273     dcqs.set_completed_queue_padding(curr_queue_size);
1274   } else {
1275     dcqs.set_completed_queue_padding(0);
1276   }
1277   dcqs.notify_if_necessary();
1278 }
1279 
1280 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1281   return get_new_size_prediction(_rs_length_diff_seq);
1282 }
1283 
1284 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1285   return get_new_prediction(_alloc_rate_ms_seq);
1286 }
1287 
1288 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1289   return get_new_prediction(_cost_per_card_ms_seq);
1290 }
1291 
1292 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1293   return get_new_prediction(_cost_scan_hcc_seq);
1294 }
1295 
1296 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1297   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1298 }
1299 
1300 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1301   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1302 }
1303 
1304 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1305   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1306     return predict_young_cards_per_entry_ratio();
1307   } else {
1308     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1309   }
1310 }
1311 
1312 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1313   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1314 }
1315 
1316 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1317   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1318 }
1319 
1320 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1321   if (collector_state()->gcs_are_young()) {
1322     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1323   } else {
1324     return predict_mixed_rs_scan_time_ms(card_num);
1325   }
1326 }
1327 
1328 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1329   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1330     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1331   } else {
1332     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1333   }
1334 }
1335 
1336 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1337   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1338     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1339   } else {
1340     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1341   }
1342 }
1343 
1344 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1345   if (collector_state()->during_concurrent_mark()) {
1346     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1347   } else {
1348     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1349   }
1350 }
1351 
1352 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1353   return get_new_prediction(_constant_other_time_ms_seq);
1354 }
1355 
1356 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1357   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1358 }
1359 
1360 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1361   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1362 }
1363 
1364 double G1CollectorPolicy::predict_remark_time_ms() const {
1365   return get_new_prediction(_concurrent_mark_remark_times_ms);
1366 }
1367 
1368 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1369   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1370 }
1371 
1372 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1373   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1374   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1375   double pred = get_new_prediction(seq);
1376   if (pred > 1.0) {
1377     pred = 1.0;
1378   }
1379   return pred;
1380 }
1381 
1382 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1383   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1384 }
1385 
1386 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1387   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1388 }
1389 
1390 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1391                                                        size_t scanned_cards) const {
1392   return
1393     predict_rs_update_time_ms(pending_cards) +
1394     predict_rs_scan_time_ms(scanned_cards) +
1395     predict_constant_other_time_ms();
1396 }
1397 
1398 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1399   size_t rs_length = predict_rs_length_diff();
1400   size_t card_num;
1401   if (collector_state()->gcs_are_young()) {
1402     card_num = predict_young_card_num(rs_length);
1403   } else {
1404     card_num = predict_non_young_card_num(rs_length);
1405   }
1406   return predict_base_elapsed_time_ms(pending_cards, card_num);
1407 }
1408 
1409 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1410   size_t bytes_to_copy;
1411   if (hr->is_marked())
1412     bytes_to_copy = hr->max_live_bytes();
1413   else {
1414     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1415     int age = hr->age_in_surv_rate_group();
1416     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1417     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1418   }
1419   return bytes_to_copy;
1420 }
1421 
1422 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1423                                                          bool for_young_gc) const {
1424   size_t rs_length = hr->rem_set()->occupied();
1425   size_t card_num;
1426 
1427   // Predicting the number of cards is based on which type of GC
1428   // we're predicting for.
1429   if (for_young_gc) {
1430     card_num = predict_young_card_num(rs_length);
1431   } else {
1432     card_num = predict_non_young_card_num(rs_length);
1433   }
1434   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1435 
1436   double region_elapsed_time_ms =
1437     predict_rs_scan_time_ms(card_num) +
1438     predict_object_copy_time_ms(bytes_to_copy);
1439 
1440   // The prediction of the "other" time for this region is based
1441   // upon the region type and NOT the GC type.
1442   if (hr->is_young()) {
1443     region_elapsed_time_ms += predict_young_other_time_ms(1);
1444   } else {
1445     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1446   }
1447   return region_elapsed_time_ms;
1448 }
1449 
1450 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1451                                                  uint survivor_cset_region_length) {
1452   _eden_cset_region_length     = eden_cset_region_length;
1453   _survivor_cset_region_length = survivor_cset_region_length;
1454   _old_cset_region_length      = 0;
1455 }
1456 
1457 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1458   _recorded_rs_lengths = rs_lengths;
1459 }
1460 
1461 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1462                                                double elapsed_ms) {
1463   _recent_gc_times_ms->add(elapsed_ms);
1464   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1465   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1466 }
1467 
1468 void G1CollectorPolicy::clear_ratio_check_data() {
1469   _ratio_over_threshold_count = 0;
1470   _ratio_over_threshold_sum = 0.0;
1471   _pauses_since_start = 0;
1472 }
1473 
1474 size_t G1CollectorPolicy::expansion_amount() {
1475   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1476   double last_gc_overhead = _last_pause_time_ratio * 100.0;
1477   double threshold = _gc_overhead_perc;
1478   size_t expand_bytes = 0;
1479 
1480   // If the heap is at less than half its maximum size, scale the threshold down,
1481   // to a limit of 1. Thus the smaller the heap is, the more likely it is to expand,
1482   // though the scaling code will likely keep the increase small.
1483   if (_g1->capacity() <= _g1->max_capacity() / 2) {
1484     threshold *= (double)_g1->capacity() / (double)(_g1->max_capacity() / 2);
1485     threshold = MAX2(threshold, 1.0);
1486   }
1487 
1488   // If the last GC time ratio is over the threshold, increment the count of
1489   // times it has been exceeded, and add this ratio to the sum of exceeded
1490   // ratios.
1491   if (last_gc_overhead > threshold) {
1492     _ratio_over_threshold_count++;
1493     _ratio_over_threshold_sum += last_gc_overhead;
1494   }
1495 
1496   // Check if we've had enough GC time ratio checks that were over the
1497   // threshold to trigger an expansion. We'll also expand if we've
1498   // reached the end of the history buffer and the average of all entries
1499   // is still over the threshold. This indicates a smaller number of GCs were
1500   // long enough to make the average exceed the threshold.
1501   bool filled_history_buffer = _pauses_since_start == NumPrevPausesForHeuristics;
1502   if ((_ratio_over_threshold_count == MinOverThresholdForGrowth) ||
1503       (filled_history_buffer && (recent_gc_overhead > threshold))) {
1504     size_t min_expand_bytes = HeapRegion::GrainBytes;
1505     size_t reserved_bytes = _g1->max_capacity();
1506     size_t committed_bytes = _g1->capacity();
1507     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1508     size_t expand_bytes_via_pct =
1509       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1510     double scale_factor = 1.0;
1511 
1512     // If the current size is less than 1/4 of the Initial heap size, expand
1513     // by half of the delta between the current and Initial sizes. IE, grow
1514     // back quickly.
1515     //
1516     // Otherwise, take the current size, or G1ExpandByPercentOfAvailable % of
1517     // the available expansion space, whichever is smaller, as the base
1518     // expansion size. Then possibly scale this size according to how much the
1519     // threshold has (on average) been exceeded by. If the delta is small
1520     // (less than the StartScaleDownAt value), scale the size down linearly, but
1521     // not by less than MinScaleDownFactor. If the delta is large (greater than
1522     // the StartScaleUpAt value), scale up, but adding no more than MaxScaleUpFactor
1523     // times the base size. The scaling will be linear in the range from
1524     // StartScaleUpAt to (StartScaleUpAt + ScaleUpRange). In other words,
1525     // ScaleUpRange sets the rate of scaling up.
1526     if (committed_bytes < InitialHeapSize / 4) {
1527       expand_bytes = (InitialHeapSize - committed_bytes) / 2;
1528     } else {
1529       double const MinScaleDownFactor = 0.2;
1530       double const MaxScaleUpFactor = 2;
1531       double const StartScaleDownAt = _gc_overhead_perc;
1532       double const StartScaleUpAt = _gc_overhead_perc * 1.5;
1533       double const ScaleUpRange = _gc_overhead_perc * 2.0;
1534 
1535       double ratio_delta;
1536       if (filled_history_buffer) {
1537         ratio_delta = recent_gc_overhead - threshold;
1538       } else {
1539         ratio_delta = (_ratio_over_threshold_sum/_ratio_over_threshold_count) - threshold;
1540       }
1541 
1542       expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1543       if (ratio_delta < StartScaleDownAt) {
1544         scale_factor = ratio_delta / StartScaleDownAt;
1545         scale_factor = MAX2(scale_factor, MinScaleDownFactor);
1546       } else if (ratio_delta > StartScaleUpAt) {
1547         scale_factor = 1 + ((ratio_delta - StartScaleUpAt) / ScaleUpRange);
1548         scale_factor = MIN2(scale_factor, MaxScaleUpFactor);
1549       }
1550     }
1551 
1552     log_debug(gc, ergo, heap)("Attempt heap expansion (recent GC overhead higher than threshold after GC) "
1553                               "recent GC overhead: %1.2f %% threshold: %1.2f %% uncommitted: " SIZE_FORMAT "B base expansion amount and scale: " SIZE_FORMAT "B (%1.2f%%)",
1554                               recent_gc_overhead, threshold, uncommitted_bytes, expand_bytes, scale_factor * 100);
1555 
1556     expand_bytes = static_cast<size_t>(expand_bytes * scale_factor);
1557 
1558     // Ensure the expansion size is at least the minimum growth amount
1559     // and at most the remaining uncommitted byte size.
1560     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1561     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1562 
1563     clear_ratio_check_data();
1564   } else {
1565     // An expansion was not triggered. If we've started counting, increment
1566     // the number of checks we've made in the current window.  If we've
1567     // reached the end of the window without resizing, clear the counters to
1568     // start again the next time we see a ratio above the threshold.
1569     if (_ratio_over_threshold_count > 0) {
1570       _pauses_since_start++;
1571       if (_pauses_since_start > NumPrevPausesForHeuristics) {
1572         clear_ratio_check_data();
1573       }
1574     }
1575   }
1576 
1577   return expand_bytes;
1578 }
1579 
1580 void G1CollectorPolicy::print_tracing_info() const {
1581   _trace_young_gen_time_data.print();
1582   _trace_old_gen_time_data.print();
1583 }
1584 
1585 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1586 #ifndef PRODUCT
1587   _short_lived_surv_rate_group->print_surv_rate_summary();
1588   // add this call for any other surv rate groups
1589 #endif // PRODUCT
1590 }
1591 
1592 bool G1CollectorPolicy::is_young_list_full() const {
1593   uint young_list_length = _g1->young_list()->length();
1594   uint young_list_target_length = _young_list_target_length;
1595   return young_list_length >= young_list_target_length;
1596 }
1597 
1598 bool G1CollectorPolicy::can_expand_young_list() const {
1599   uint young_list_length = _g1->young_list()->length();
1600   uint young_list_max_length = _young_list_max_length;
1601   return young_list_length < young_list_max_length;
1602 }
1603 
1604 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1605   uint expansion_region_num = 0;
1606   if (GCLockerEdenExpansionPercent > 0) {
1607     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1608     double expansion_region_num_d = perc * (double) _young_list_target_length;
1609     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1610     // less than 1.0) we'll get 1.
1611     expansion_region_num = (uint) ceil(expansion_region_num_d);
1612   } else {
1613     assert(expansion_region_num == 0, "sanity");
1614   }
1615   _young_list_max_length = _young_list_target_length + expansion_region_num;
1616   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1617 }
1618 
1619 // Calculates survivor space parameters.
1620 void G1CollectorPolicy::update_survivors_policy() {
1621   double max_survivor_regions_d =
1622                  (double) _young_list_target_length / (double) SurvivorRatio;
1623   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1624   // smaller than 1.0) we'll get 1.
1625   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1626 
1627   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1628         HeapRegion::GrainWords * _max_survivor_regions, counters());
1629 }
1630 
1631 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1632   // We actually check whether we are marking here and not if we are in a
1633   // reclamation phase. This means that we will schedule a concurrent mark
1634   // even while we are still in the process of reclaiming memory.
1635   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1636   if (!during_cycle) {
1637     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
1638     collector_state()->set_initiate_conc_mark_if_possible(true);
1639     return true;
1640   } else {
1641     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
1642     return false;
1643   }
1644 }
1645 
1646 void G1CollectorPolicy::initiate_conc_mark() {
1647   collector_state()->set_during_initial_mark_pause(true);
1648   collector_state()->set_initiate_conc_mark_if_possible(false);
1649 }
1650 
1651 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1652   // We are about to decide on whether this pause will be an
1653   // initial-mark pause.
1654 
1655   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1656   // will set it here if we have to. However, it should be cleared by
1657   // the end of the pause (it's only set for the duration of an
1658   // initial-mark pause).
1659   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1660 
1661   if (collector_state()->initiate_conc_mark_if_possible()) {
1662     // We had noticed on a previous pause that the heap occupancy has
1663     // gone over the initiating threshold and we should start a
1664     // concurrent marking cycle. So we might initiate one.
1665 
1666     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1667       // Initiate a new initial mark if there is no marking or reclamation going on.
1668       initiate_conc_mark();
1669       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
1670     } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
1671       // Initiate a user requested initial mark. An initial mark must be young only
1672       // GC, so the collector state must be updated to reflect this.
1673       collector_state()->set_gcs_are_young(true);
1674       collector_state()->set_last_young_gc(false);
1675 
1676       abort_time_to_mixed_tracking();
1677       initiate_conc_mark();
1678       log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
1679     } else {
1680       // The concurrent marking thread is still finishing up the
1681       // previous cycle. If we start one right now the two cycles
1682       // overlap. In particular, the concurrent marking thread might
1683       // be in the process of clearing the next marking bitmap (which
1684       // we will use for the next cycle if we start one). Starting a
1685       // cycle now will be bad given that parts of the marking
1686       // information might get cleared by the marking thread. And we
1687       // cannot wait for the marking thread to finish the cycle as it
1688       // periodically yields while clearing the next marking bitmap
1689       // and, if it's in a yield point, it's waiting for us to
1690       // finish. So, at this point we will not start a cycle and we'll
1691       // let the concurrent marking thread complete the last one.
1692       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
1693     }
1694   }
1695 }
1696 
1697 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1698   G1CollectedHeap* _g1h;
1699   CSetChooserParUpdater _cset_updater;
1700 
1701 public:
1702   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1703                            uint chunk_size) :
1704     _g1h(G1CollectedHeap::heap()),
1705     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1706 
1707   bool doHeapRegion(HeapRegion* r) {
1708     // Do we have any marking information for this region?
1709     if (r->is_marked()) {
1710       // We will skip any region that's currently used as an old GC
1711       // alloc region (we should not consider those for collection
1712       // before we fill them up).
1713       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1714         _cset_updater.add_region(r);
1715       }
1716     }
1717     return false;
1718   }
1719 };
1720 
1721 class ParKnownGarbageTask: public AbstractGangTask {
1722   CollectionSetChooser* _hrSorted;
1723   uint _chunk_size;
1724   G1CollectedHeap* _g1;
1725   HeapRegionClaimer _hrclaimer;
1726 
1727 public:
1728   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1729       AbstractGangTask("ParKnownGarbageTask"),
1730       _hrSorted(hrSorted), _chunk_size(chunk_size),
1731       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1732 
1733   void work(uint worker_id) {
1734     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1735     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1736   }
1737 };
1738 
1739 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1740   assert(n_workers > 0, "Active gc workers should be greater than 0");
1741   const uint overpartition_factor = 4;
1742   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1743   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1744 }
1745 
1746 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1747   cset_chooser()->clear();
1748 
1749   WorkGang* workers = _g1->workers();
1750   uint n_workers = workers->active_workers();
1751 
1752   uint n_regions = _g1->num_regions();
1753   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1754   cset_chooser()->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1755   ParKnownGarbageTask par_known_garbage_task(cset_chooser(), chunk_size, n_workers);
1756   workers->run_task(&par_known_garbage_task);
1757 
1758   cset_chooser()->sort_regions();
1759 
1760   double end_sec = os::elapsedTime();
1761   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1762   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1763   _prev_collection_pause_end_ms += elapsed_time_ms;
1764 
1765   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1766 }
1767 
1768 // Add the heap region at the head of the non-incremental collection set
1769 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1770   assert(_inc_cset_build_state == Active, "Precondition");
1771   assert(hr->is_old(), "the region should be old");
1772 
1773   assert(!hr->in_collection_set(), "should not already be in the CSet");
1774   _g1->register_old_region_with_cset(hr);
1775   hr->set_next_in_collection_set(_collection_set);
1776   _collection_set = hr;
1777   _collection_set_bytes_used_before += hr->used();
1778   size_t rs_length = hr->rem_set()->occupied();
1779   _recorded_rs_lengths += rs_length;
1780   _old_cset_region_length += 1;
1781 }
1782 
1783 // Initialize the per-collection-set information
1784 void G1CollectorPolicy::start_incremental_cset_building() {
1785   assert(_inc_cset_build_state == Inactive, "Precondition");
1786 
1787   _inc_cset_head = NULL;
1788   _inc_cset_tail = NULL;
1789   _inc_cset_bytes_used_before = 0;
1790 
1791   _inc_cset_max_finger = 0;
1792   _inc_cset_recorded_rs_lengths = 0;
1793   _inc_cset_recorded_rs_lengths_diffs = 0;
1794   _inc_cset_predicted_elapsed_time_ms = 0.0;
1795   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1796   _inc_cset_build_state = Active;
1797 }
1798 
1799 void G1CollectorPolicy::finalize_incremental_cset_building() {
1800   assert(_inc_cset_build_state == Active, "Precondition");
1801   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1802 
1803   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1804   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1805   // that adds a new region to the CSet. Further updates by the
1806   // concurrent refinement thread that samples the young RSet lengths
1807   // are accumulated in the *_diffs fields. Here we add the diffs to
1808   // the "main" fields.
1809 
1810   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1811     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1812   } else {
1813     // This is defensive. The diff should in theory be always positive
1814     // as RSets can only grow between GCs. However, given that we
1815     // sample their size concurrently with other threads updating them
1816     // it's possible that we might get the wrong size back, which
1817     // could make the calculations somewhat inaccurate.
1818     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1819     if (_inc_cset_recorded_rs_lengths >= diffs) {
1820       _inc_cset_recorded_rs_lengths -= diffs;
1821     } else {
1822       _inc_cset_recorded_rs_lengths = 0;
1823     }
1824   }
1825   _inc_cset_predicted_elapsed_time_ms +=
1826                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1827 
1828   _inc_cset_recorded_rs_lengths_diffs = 0;
1829   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1830 }
1831 
1832 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1833   // This routine is used when:
1834   // * adding survivor regions to the incremental cset at the end of an
1835   //   evacuation pause,
1836   // * adding the current allocation region to the incremental cset
1837   //   when it is retired, and
1838   // * updating existing policy information for a region in the
1839   //   incremental cset via young list RSet sampling.
1840   // Therefore this routine may be called at a safepoint by the
1841   // VM thread, or in-between safepoints by mutator threads (when
1842   // retiring the current allocation region) or a concurrent
1843   // refine thread (RSet sampling).
1844 
1845   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1846   size_t used_bytes = hr->used();
1847   _inc_cset_recorded_rs_lengths += rs_length;
1848   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1849   _inc_cset_bytes_used_before += used_bytes;
1850 
1851   // Cache the values we have added to the aggregated information
1852   // in the heap region in case we have to remove this region from
1853   // the incremental collection set, or it is updated by the
1854   // rset sampling code
1855   hr->set_recorded_rs_length(rs_length);
1856   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1857 }
1858 
1859 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1860                                                      size_t new_rs_length) {
1861   // Update the CSet information that is dependent on the new RS length
1862   assert(hr->is_young(), "Precondition");
1863   assert(!SafepointSynchronize::is_at_safepoint(),
1864                                                "should not be at a safepoint");
1865 
1866   // We could have updated _inc_cset_recorded_rs_lengths and
1867   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1868   // that atomically, as this code is executed by a concurrent
1869   // refinement thread, potentially concurrently with a mutator thread
1870   // allocating a new region and also updating the same fields. To
1871   // avoid the atomic operations we accumulate these updates on two
1872   // separate fields (*_diffs) and we'll just add them to the "main"
1873   // fields at the start of a GC.
1874 
1875   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1876   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1877   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1878 
1879   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1880   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1881   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1882   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1883 
1884   hr->set_recorded_rs_length(new_rs_length);
1885   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1886 }
1887 
1888 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1889   assert(hr->is_young(), "invariant");
1890   assert(hr->young_index_in_cset() > -1, "should have already been set");
1891   assert(_inc_cset_build_state == Active, "Precondition");
1892 
1893   // We need to clear and set the cached recorded/cached collection set
1894   // information in the heap region here (before the region gets added
1895   // to the collection set). An individual heap region's cached values
1896   // are calculated, aggregated with the policy collection set info,
1897   // and cached in the heap region here (initially) and (subsequently)
1898   // by the Young List sampling code.
1899 
1900   size_t rs_length = hr->rem_set()->occupied();
1901   add_to_incremental_cset_info(hr, rs_length);
1902 
1903   HeapWord* hr_end = hr->end();
1904   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1905 
1906   assert(!hr->in_collection_set(), "invariant");
1907   _g1->register_young_region_with_cset(hr);
1908   assert(hr->next_in_collection_set() == NULL, "invariant");
1909 }
1910 
1911 // Add the region at the RHS of the incremental cset
1912 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1913   // We should only ever be appending survivors at the end of a pause
1914   assert(hr->is_survivor(), "Logic");
1915 
1916   // Do the 'common' stuff
1917   add_region_to_incremental_cset_common(hr);
1918 
1919   // Now add the region at the right hand side
1920   if (_inc_cset_tail == NULL) {
1921     assert(_inc_cset_head == NULL, "invariant");
1922     _inc_cset_head = hr;
1923   } else {
1924     _inc_cset_tail->set_next_in_collection_set(hr);
1925   }
1926   _inc_cset_tail = hr;
1927 }
1928 
1929 // Add the region to the LHS of the incremental cset
1930 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1931   // Survivors should be added to the RHS at the end of a pause
1932   assert(hr->is_eden(), "Logic");
1933 
1934   // Do the 'common' stuff
1935   add_region_to_incremental_cset_common(hr);
1936 
1937   // Add the region at the left hand side
1938   hr->set_next_in_collection_set(_inc_cset_head);
1939   if (_inc_cset_head == NULL) {
1940     assert(_inc_cset_tail == NULL, "Invariant");
1941     _inc_cset_tail = hr;
1942   }
1943   _inc_cset_head = hr;
1944 }
1945 
1946 #ifndef PRODUCT
1947 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1948   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1949 
1950   st->print_cr("\nCollection_set:");
1951   HeapRegion* csr = list_head;
1952   while (csr != NULL) {
1953     HeapRegion* next = csr->next_in_collection_set();
1954     assert(csr->in_collection_set(), "bad CS");
1955     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
1956                  HR_FORMAT_PARAMS(csr),
1957                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
1958                  csr->age_in_surv_rate_group_cond());
1959     csr = next;
1960   }
1961 }
1962 #endif // !PRODUCT
1963 
1964 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
1965   // Returns the given amount of reclaimable bytes (that represents
1966   // the amount of reclaimable space still to be collected) as a
1967   // percentage of the current heap capacity.
1968   size_t capacity_bytes = _g1->capacity();
1969   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1970 }
1971 
1972 void G1CollectorPolicy::maybe_start_marking() {
1973   if (need_to_start_conc_mark("end of GC")) {
1974     // Note: this might have already been set, if during the last
1975     // pause we decided to start a cycle but at the beginning of
1976     // this pause we decided to postpone it. That's OK.
1977     collector_state()->set_initiate_conc_mark_if_possible(true);
1978   }
1979 }
1980 
1981 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
1982   assert(!collector_state()->full_collection(), "must be");
1983   if (collector_state()->during_initial_mark_pause()) {
1984     assert(collector_state()->last_gc_was_young(), "must be");
1985     assert(!collector_state()->last_young_gc(), "must be");
1986     return InitialMarkGC;
1987   } else if (collector_state()->last_young_gc()) {
1988     assert(!collector_state()->during_initial_mark_pause(), "must be");
1989     assert(collector_state()->last_gc_was_young(), "must be");
1990     return LastYoungGC;
1991   } else if (!collector_state()->last_gc_was_young()) {
1992     assert(!collector_state()->during_initial_mark_pause(), "must be");
1993     assert(!collector_state()->last_young_gc(), "must be");
1994     return MixedGC;
1995   } else {
1996     assert(collector_state()->last_gc_was_young(), "must be");
1997     assert(!collector_state()->during_initial_mark_pause(), "must be");
1998     assert(!collector_state()->last_young_gc(), "must be");
1999     return YoungOnlyGC;
2000   }
2001 }
2002 
2003 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2004   // Manage the MMU tracker. For some reason it ignores Full GCs.
2005   if (kind != FullGC) {
2006     _mmu_tracker->add_pause(start, end);
2007   }
2008   // Manage the mutator time tracking from initial mark to first mixed gc.
2009   switch (kind) {
2010     case FullGC:
2011       abort_time_to_mixed_tracking();
2012       break;
2013     case Cleanup:
2014     case Remark:
2015     case YoungOnlyGC:
2016     case LastYoungGC:
2017       _initial_mark_to_mixed.add_pause(end - start);
2018       break;
2019     case InitialMarkGC:
2020       _initial_mark_to_mixed.record_initial_mark_end(end);
2021       break;
2022     case MixedGC:
2023       _initial_mark_to_mixed.record_mixed_gc_start(start);
2024       break;
2025     default:
2026       ShouldNotReachHere();
2027   }
2028 }
2029 
2030 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2031   _initial_mark_to_mixed.reset();
2032 }
2033 
2034 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2035                                                 const char* false_action_str) const {
2036   if (cset_chooser()->is_empty()) {
2037     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
2038     return false;
2039   }
2040 
2041   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2042   size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2043   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2044   double threshold = (double) G1HeapWastePercent;
2045   if (reclaimable_perc <= threshold) {
2046     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
2047                         false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2048     return false;
2049   }
2050   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
2051                       true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2052   return true;
2053 }
2054 
2055 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2056   // The min old CSet region bound is based on the maximum desired
2057   // number of mixed GCs after a cycle. I.e., even if some old regions
2058   // look expensive, we should add them to the CSet anyway to make
2059   // sure we go through the available old regions in no more than the
2060   // maximum desired number of mixed GCs.
2061   //
2062   // The calculation is based on the number of marked regions we added
2063   // to the CSet chooser in the first place, not how many remain, so
2064   // that the result is the same during all mixed GCs that follow a cycle.
2065 
2066   const size_t region_num = (size_t) cset_chooser()->length();
2067   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2068   size_t result = region_num / gc_num;
2069   // emulate ceiling
2070   if (result * gc_num < region_num) {
2071     result += 1;
2072   }
2073   return (uint) result;
2074 }
2075 
2076 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2077   // The max old CSet region bound is based on the threshold expressed
2078   // as a percentage of the heap size. I.e., it should bound the
2079   // number of old regions added to the CSet irrespective of how many
2080   // of them are available.
2081 
2082   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2083   const size_t region_num = g1h->num_regions();
2084   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2085   size_t result = region_num * perc / 100;
2086   // emulate ceiling
2087   if (100 * result < region_num * perc) {
2088     result += 1;
2089   }
2090   return (uint) result;
2091 }
2092 
2093 
2094 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2095   double young_start_time_sec = os::elapsedTime();
2096 
2097   YoungList* young_list = _g1->young_list();
2098   finalize_incremental_cset_building();
2099 
2100   guarantee(target_pause_time_ms > 0.0,
2101             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2102   guarantee(_collection_set == NULL, "Precondition");
2103 
2104   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2105   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2106 
2107   log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
2108                             _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2109 
2110   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2111 
2112   if (collector_state()->last_gc_was_young()) {
2113     _trace_young_gen_time_data.increment_young_collection_count();
2114   } else {
2115     _trace_young_gen_time_data.increment_mixed_collection_count();
2116   }
2117 
2118   // The young list is laid with the survivor regions from the previous
2119   // pause are appended to the RHS of the young list, i.e.
2120   //   [Newly Young Regions ++ Survivors from last pause].
2121 
2122   uint survivor_region_length = young_list->survivor_length();
2123   uint eden_region_length = young_list->eden_length();
2124   init_cset_region_lengths(eden_region_length, survivor_region_length);
2125 
2126   HeapRegion* hr = young_list->first_survivor_region();
2127   while (hr != NULL) {
2128     assert(hr->is_survivor(), "badly formed young list");
2129     // There is a convention that all the young regions in the CSet
2130     // are tagged as "eden", so we do this for the survivors here. We
2131     // use the special set_eden_pre_gc() as it doesn't check that the
2132     // region is free (which is not the case here).
2133     hr->set_eden_pre_gc();
2134     hr = hr->get_next_young_region();
2135   }
2136 
2137   // Clear the fields that point to the survivor list - they are all young now.
2138   young_list->clear_survivors();
2139 
2140   _collection_set = _inc_cset_head;
2141   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2142   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2143 
2144   log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
2145                             eden_region_length, survivor_region_length, _inc_cset_predicted_elapsed_time_ms, target_pause_time_ms);
2146 
2147   // The number of recorded young regions is the incremental
2148   // collection set's current size
2149   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2150 
2151   double young_end_time_sec = os::elapsedTime();
2152   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2153 
2154   return time_remaining_ms;
2155 }
2156 
2157 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2158   double non_young_start_time_sec = os::elapsedTime();
2159   double predicted_old_time_ms = 0.0;
2160 
2161 
2162   if (!collector_state()->gcs_are_young()) {
2163     cset_chooser()->verify();
2164     const uint min_old_cset_length = calc_min_old_cset_length();
2165     const uint max_old_cset_length = calc_max_old_cset_length();
2166 
2167     uint expensive_region_num = 0;
2168     bool check_time_remaining = adaptive_young_list_length();
2169 
2170     HeapRegion* hr = cset_chooser()->peek();
2171     while (hr != NULL) {
2172       if (old_cset_region_length() >= max_old_cset_length) {
2173         // Added maximum number of old regions to the CSet.
2174         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). old %u regions, max %u regions",
2175                                   old_cset_region_length(), max_old_cset_length);
2176         break;
2177       }
2178 
2179 
2180       // Stop adding regions if the remaining reclaimable space is
2181       // not above G1HeapWastePercent.
2182       size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
2183       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2184       double threshold = (double) G1HeapWastePercent;
2185       if (reclaimable_perc <= threshold) {
2186         // We've added enough old regions that the amount of uncollected
2187         // reclaimable space is at or below the waste threshold. Stop
2188         // adding old regions to the CSet.
2189         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). "
2190                                   "old %u regions, max %u regions, reclaimable: " SIZE_FORMAT "B (%1.2f%%) threshold: " UINTX_FORMAT "%%",
2191                                   old_cset_region_length(), max_old_cset_length, reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
2192         break;
2193       }
2194 
2195       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2196       if (check_time_remaining) {
2197         if (predicted_time_ms > time_remaining_ms) {
2198           // Too expensive for the current CSet.
2199 
2200           if (old_cset_region_length() >= min_old_cset_length) {
2201             // We have added the minimum number of old regions to the CSet,
2202             // we are done with this CSet.
2203             log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high). "
2204                                       "predicted time: %1.2fms, remaining time: %1.2fms old %u regions, min %u regions",
2205                                       predicted_time_ms, time_remaining_ms, old_cset_region_length(), min_old_cset_length);
2206             break;
2207           }
2208 
2209           // We'll add it anyway given that we haven't reached the
2210           // minimum number of old regions.
2211           expensive_region_num += 1;
2212         }
2213       } else {
2214         if (old_cset_region_length() >= min_old_cset_length) {
2215           // In the non-auto-tuning case, we'll finish adding regions
2216           // to the CSet if we reach the minimum.
2217 
2218           log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min). old %u regions, min %u regions",
2219                                     old_cset_region_length(), min_old_cset_length);
2220           break;
2221         }
2222       }
2223 
2224       // We will add this region to the CSet.
2225       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2226       predicted_old_time_ms += predicted_time_ms;
2227       cset_chooser()->pop(); // already have region via peek()
2228       _g1->old_set_remove(hr);
2229       add_old_region_to_cset(hr);
2230 
2231       hr = cset_chooser()->peek();
2232     }
2233     if (hr == NULL) {
2234       log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)");
2235     }
2236 
2237     if (expensive_region_num > 0) {
2238       // We print the information once here at the end, predicated on
2239       // whether we added any apparently expensive regions or not, to
2240       // avoid generating output per region.
2241       log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
2242                                 "old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms",
2243                                 old_cset_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
2244     }
2245 
2246     cset_chooser()->verify();
2247   }
2248 
2249   stop_incremental_cset_building();
2250 
2251   log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
2252                             old_cset_region_length(), predicted_old_time_ms, time_remaining_ms);
2253 
2254   double non_young_end_time_sec = os::elapsedTime();
2255   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2256 }
2257 
2258 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2259   if(TraceYoungGenTime) {
2260     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2261   }
2262 }
2263 
2264 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2265   if(TraceYoungGenTime) {
2266     _all_yield_times_ms.add(yield_time_ms);
2267   }
2268 }
2269 
2270 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2271   if(TraceYoungGenTime) {
2272     _total.add(pause_time_ms);
2273     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2274     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2275     _parallel.add(phase_times->cur_collection_par_time_ms());
2276     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2277     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2278     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2279     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2280     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2281     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2282 
2283     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2284       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2285       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2286       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2287       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2288       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2289 
2290     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2291     _parallel_other.add(parallel_other_time);
2292     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2293   }
2294 }
2295 
2296 void TraceYoungGenTimeData::increment_young_collection_count() {
2297   if(TraceYoungGenTime) {
2298     ++_young_pause_num;
2299   }
2300 }
2301 
2302 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2303   if(TraceYoungGenTime) {
2304     ++_mixed_pause_num;
2305   }
2306 }
2307 
2308 void TraceYoungGenTimeData::print_summary(const char* str,
2309                                           const NumberSeq* seq) const {
2310   double sum = seq->sum();
2311   tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2312                 str, sum / 1000.0, seq->avg());
2313 }
2314 
2315 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2316                                              const NumberSeq* seq) const {
2317   print_summary(str, seq);
2318   tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2319                 "(num", seq->num(), seq->sd(), seq->maximum());
2320 }
2321 
2322 void TraceYoungGenTimeData::print() const {
2323   if (!TraceYoungGenTime) {
2324     return;
2325   }
2326 
2327   tty->print_cr("ALL PAUSES");
2328   print_summary_sd("   Total", &_total);
2329   tty->cr();
2330   tty->cr();
2331   tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2332   tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2333   tty->cr();
2334 
2335   tty->print_cr("EVACUATION PAUSES");
2336 
2337   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2338     tty->print_cr("none");
2339   } else {
2340     print_summary_sd("   Evacuation Pauses", &_total);
2341     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2342     print_summary("      Parallel Time", &_parallel);
2343     print_summary("         Ext Root Scanning", &_ext_root_scan);
2344     print_summary("         SATB Filtering", &_satb_filtering);
2345     print_summary("         Update RS", &_update_rs);
2346     print_summary("         Scan RS", &_scan_rs);
2347     print_summary("         Object Copy", &_obj_copy);
2348     print_summary("         Termination", &_termination);
2349     print_summary("         Parallel Other", &_parallel_other);
2350     print_summary("      Clear CT", &_clear_ct);
2351     print_summary("      Other", &_other);
2352   }
2353   tty->cr();
2354 
2355   tty->print_cr("MISC");
2356   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2357   print_summary_sd("   Yields", &_all_yield_times_ms);
2358 }
2359 
2360 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2361   if (TraceOldGenTime) {
2362     _all_full_gc_times.add(full_gc_time_ms);
2363   }
2364 }
2365 
2366 void TraceOldGenTimeData::print() const {
2367   if (!TraceOldGenTime) {
2368     return;
2369   }
2370 
2371   if (_all_full_gc_times.num() > 0) {
2372     tty->print("\n%4d full_gcs: total time = %8.2f s",
2373       _all_full_gc_times.num(),
2374       _all_full_gc_times.sum() / 1000.0);
2375     tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2376     tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2377       _all_full_gc_times.sd(),
2378       _all_full_gc_times.maximum());
2379   }
2380 }
--- EOF ---