rev 9277 : imported patch 8140597-forcing-initial-mark-causes-abort-mixed-collections
rev 9278 : imported patch 8139874-after-full-gc-next-gc-is-always-young-only
rev 9279 : imported patch 8138740-start-initial-mark-right-after-mixed-gc-if-needed
rev 9281 : imported patch 8140689-skip-last-young-if-nothing-to-do-in-mixed
rev 9282 : dihop-changes
rev 9284 : imported patch 8136678-implement-adaptive-sizing-algorithm-for-IHOP
rev 9286 : imported patch 8136679-jfr-event-for-dynamic-ihop

   1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/concurrentMark.hpp"
  28 #include "gc/g1/concurrentMarkThread.inline.hpp"
  29 #include "gc/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc/g1/g1CollectorPolicy.hpp"
  31 #include "gc/g1/g1IHOPControl.hpp"
  32 #include "gc/g1/g1ErgoVerbose.hpp"
  33 #include "gc/g1/g1GCPhaseTimes.hpp"
  34 #include "gc/g1/g1Log.hpp"
  35 #include "gc/g1/heapRegion.inline.hpp"
  36 #include "gc/g1/heapRegionRemSet.hpp"
  37 #include "gc/shared/gcPolicyCounters.hpp"
  38 #include "runtime/arguments.hpp"
  39 #include "runtime/java.hpp"
  40 #include "runtime/mutexLocker.hpp"
  41 #include "utilities/debug.hpp"
  42 
  43 // Different defaults for different number of GC threads
  44 // They were chosen by running GCOld and SPECjbb on debris with different
  45 //   numbers of GC threads and choosing them based on the results
  46 
  47 // all the same
  48 static double rs_length_diff_defaults[] = {
  49   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
  50 };
  51 
  52 static double cost_per_card_ms_defaults[] = {
  53   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
  54 };
  55 
  56 // all the same
  57 static double young_cards_per_entry_ratio_defaults[] = {
  58   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
  59 };
  60 
  61 static double cost_per_entry_ms_defaults[] = {
  62   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
  63 };
  64 
  65 static double cost_per_byte_ms_defaults[] = {
  66   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
  67 };
  68 
  69 // these should be pretty consistent
  70 static double constant_other_time_ms_defaults[] = {
  71   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
  72 };
  73 
  74 
  75 static double young_other_cost_per_region_ms_defaults[] = {
  76   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
  77 };
  78 
  79 static double non_young_other_cost_per_region_ms_defaults[] = {
  80   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
  81 };
  82 
  83 G1CollectorPolicy::G1CollectorPolicy() :
  84   _predictor(G1ConfidencePercent / 100.0),
  85   _parallel_gc_threads(ParallelGCThreads),
  86 
  87   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  88   _stop_world_start(0.0),
  89 
  90   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  91   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  92 
  93   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  94   _prev_collection_pause_end_ms(0.0),
  95   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _cost_scan_hcc_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 105   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 106   _non_young_other_cost_per_region_ms_seq(
 107                                          new TruncatedSeq(TruncatedSeqLength)),
 108 
 109   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 110   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 111 
 112   _pause_time_target_ms((double) MaxGCPauseMillis),
 113 
 114   _recent_prev_end_times_for_all_gcs_sec(
 115                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 116 
 117   _recent_avg_pause_time_ratio(0.0),
 118   _rs_lengths_prediction(0),
 119   _max_survivor_regions(0),
 120 
 121   _eden_used_bytes_before_gc(0),
 122   _survivor_used_bytes_before_gc(0),
 123   _heap_used_bytes_before_gc(0),
 124   _metaspace_used_bytes_before_gc(0),
 125   _eden_capacity_bytes_before_gc(0),
 126   _heap_capacity_bytes_before_gc(0),
 127 
 128   _eden_cset_region_length(0),
 129   _survivor_cset_region_length(0),
 130   _old_cset_region_length(0),
 131 
 132   _collection_set(NULL),
 133   _collection_set_bytes_used_before(0),
 134 
 135   // Incremental CSet attributes
 136   _inc_cset_build_state(Inactive),
 137   _inc_cset_head(NULL),
 138   _inc_cset_tail(NULL),
 139   _inc_cset_bytes_used_before(0),
 140   _inc_cset_max_finger(NULL),
 141   _inc_cset_recorded_rs_lengths(0),
 142   _inc_cset_recorded_rs_lengths_diffs(0),
 143   _inc_cset_predicted_elapsed_time_ms(0.0),
 144   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 145 
 146   // add here any more surv rate groups
 147   _recorded_survivor_regions(0),
 148   _recorded_survivor_head(NULL),
 149   _recorded_survivor_tail(NULL),
 150   _survivors_age_table(true),
 151 
 152   _gc_overhead_perc(0.0),
 153 
 154   _last_old_allocated_bytes(0),
 155   _ihop_control(NULL),
 156   _initial_mark_to_mixed() {
 157 
 158   // SurvRateGroups below must be initialized after the predictor because they
 159   // indirectly use it through this object passed to their constructor.
 160   _short_lived_surv_rate_group =
 161     new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
 162   _survivor_surv_rate_group =
 163     new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
 164 
 165   // Set up the region size and associated fields. Given that the
 166   // policy is created before the heap, we have to set this up here,
 167   // so it's done as soon as possible.
 168 
 169   // It would have been natural to pass initial_heap_byte_size() and
 170   // max_heap_byte_size() to setup_heap_region_size() but those have
 171   // not been set up at this point since they should be aligned with
 172   // the region size. So, there is a circular dependency here. We base
 173   // the region size on the heap size, but the heap size should be
 174   // aligned with the region size. To get around this we use the
 175   // unaligned values for the heap.
 176   HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
 177   HeapRegionRemSet::setup_remset_size();
 178 
 179   G1ErgoVerbose::initialize();
 180   if (PrintAdaptiveSizePolicy) {
 181     // Currently, we only use a single switch for all the heuristics.
 182     G1ErgoVerbose::set_enabled(true);
 183     // Given that we don't currently have a verboseness level
 184     // parameter, we'll hardcode this to high. This can be easily
 185     // changed in the future.
 186     G1ErgoVerbose::set_level(ErgoHigh);
 187   } else {
 188     G1ErgoVerbose::set_enabled(false);
 189   }
 190 
 191   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 192   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 193 
 194   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 195 
 196   int index = MIN2(_parallel_gc_threads - 1, 7);
 197 
 198   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 199   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 200   _cost_scan_hcc_seq->add(0.0);
 201   _young_cards_per_entry_ratio_seq->add(
 202                                   young_cards_per_entry_ratio_defaults[index]);
 203   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 204   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 205   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 206   _young_other_cost_per_region_ms_seq->add(
 207                                young_other_cost_per_region_ms_defaults[index]);
 208   _non_young_other_cost_per_region_ms_seq->add(
 209                            non_young_other_cost_per_region_ms_defaults[index]);
 210 
 211   // Below, we might need to calculate the pause time target based on
 212   // the pause interval. When we do so we are going to give G1 maximum
 213   // flexibility and allow it to do pauses when it needs to. So, we'll
 214   // arrange that the pause interval to be pause time target + 1 to
 215   // ensure that a) the pause time target is maximized with respect to
 216   // the pause interval and b) we maintain the invariant that pause
 217   // time target < pause interval. If the user does not want this
 218   // maximum flexibility, they will have to set the pause interval
 219   // explicitly.
 220 
 221   // First make sure that, if either parameter is set, its value is
 222   // reasonable.
 223   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 224     if (MaxGCPauseMillis < 1) {
 225       vm_exit_during_initialization("MaxGCPauseMillis should be "
 226                                     "greater than 0");
 227     }
 228   }
 229   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 230     if (GCPauseIntervalMillis < 1) {
 231       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 232                                     "greater than 0");
 233     }
 234   }
 235 
 236   // Then, if the pause time target parameter was not set, set it to
 237   // the default value.
 238   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 239     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 240       // The default pause time target in G1 is 200ms
 241       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 242     } else {
 243       // We do not allow the pause interval to be set without the
 244       // pause time target
 245       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 246                                     "without setting MaxGCPauseMillis");
 247     }
 248   }
 249 
 250   // Then, if the interval parameter was not set, set it according to
 251   // the pause time target (this will also deal with the case when the
 252   // pause time target is the default value).
 253   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 254     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 255   }
 256 
 257   // Finally, make sure that the two parameters are consistent.
 258   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 259     char buffer[256];
 260     jio_snprintf(buffer, 256,
 261                  "MaxGCPauseMillis (%u) should be less than "
 262                  "GCPauseIntervalMillis (%u)",
 263                  MaxGCPauseMillis, GCPauseIntervalMillis);
 264     vm_exit_during_initialization(buffer);
 265   }
 266 
 267   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 268   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 269   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 270 
 271   // start conservatively (around 50ms is about right)
 272   _concurrent_mark_remark_times_ms->add(0.05);
 273   _concurrent_mark_cleanup_times_ms->add(0.20);
 274   _tenuring_threshold = MaxTenuringThreshold;
 275 
 276   assert(GCTimeRatio > 0,
 277          "we should have set it to a default value set_g1_gc_flags() "
 278          "if a user set it to 0");
 279   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 280 
 281   uintx reserve_perc = G1ReservePercent;
 282   // Put an artificial ceiling on this so that it's not set to a silly value.
 283   if (reserve_perc > 50) {
 284     reserve_perc = 50;
 285     warning("G1ReservePercent is set to a value that is too large, "
 286             "it's been updated to " UINTX_FORMAT, reserve_perc);
 287   }
 288   _reserve_factor = (double) reserve_perc / 100.0;
 289   // This will be set when the heap is expanded
 290   // for the first time during initialization.
 291   _reserve_regions = 0;
 292 
 293   _collectionSetChooser = new CollectionSetChooser();
 294 }
 295 
 296 G1CollectorPolicy::~G1CollectorPolicy() {
 297   if (_ihop_control != NULL) {
 298     delete _ihop_control;
 299   }
 300 }
 301 
 302 double G1CollectorPolicy::get_new_prediction(TruncatedSeq const* seq) const {
 303   return _predictor.get_new_prediction(seq);
 304 }
 305 
 306 void G1CollectorPolicy::initialize_alignments() {
 307   _space_alignment = HeapRegion::GrainBytes;
 308   size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
 309   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
 310   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 311 }
 312 
 313 void G1CollectorPolicy::initialize_flags() {
 314   if (G1HeapRegionSize != HeapRegion::GrainBytes) {
 315     FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
 316   }
 317 
 318   if (SurvivorRatio < 1) {
 319     vm_exit_during_initialization("Invalid survivor ratio specified");
 320   }
 321   CollectorPolicy::initialize_flags();
 322   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 323 }
 324 
 325 void G1CollectorPolicy::post_heap_initialize() {
 326   uintx max_regions = G1CollectedHeap::heap()->max_regions();
 327   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;
 328   if (max_young_size != MaxNewSize) {
 329     FLAG_SET_ERGO(size_t, MaxNewSize, max_young_size);
 330   }
 331 
 332   _ihop_control = create_ihop_control();
 333 }
 334 
 335 G1CollectorState* G1CollectorPolicy::collector_state() const { return _g1->collector_state(); }
 336 
 337 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),
 338         _min_desired_young_length(0), _max_desired_young_length(0) {
 339   if (FLAG_IS_CMDLINE(NewRatio)) {
 340     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 341       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 342     } else {
 343       _sizer_kind = SizerNewRatio;
 344       _adaptive_size = false;
 345       return;
 346     }
 347   }
 348 
 349   if (NewSize > MaxNewSize) {
 350     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 351       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 352               "A new max generation size of " SIZE_FORMAT "k will be used.",
 353               NewSize/K, MaxNewSize/K, NewSize/K);
 354     }
 355     MaxNewSize = NewSize;
 356   }
 357 
 358   if (FLAG_IS_CMDLINE(NewSize)) {
 359     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 360                                      1U);
 361     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 362       _max_desired_young_length =
 363                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 364                                   1U);
 365       _sizer_kind = SizerMaxAndNewSize;
 366       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 367     } else {
 368       _sizer_kind = SizerNewSizeOnly;
 369     }
 370   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 371     _max_desired_young_length =
 372                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 373                                   1U);
 374     _sizer_kind = SizerMaxNewSizeOnly;
 375   }
 376 }
 377 
 378 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 379   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 380   return MAX2(1U, default_value);
 381 }
 382 
 383 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 384   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 385   return MAX2(1U, default_value);
 386 }
 387 
 388 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {
 389   assert(number_of_heap_regions > 0, "Heap must be initialized");
 390 
 391   switch (_sizer_kind) {
 392     case SizerDefaults:
 393       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 394       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 395       break;
 396     case SizerNewSizeOnly:
 397       *max_young_length = calculate_default_max_length(number_of_heap_regions);
 398       *max_young_length = MAX2(*min_young_length, *max_young_length);
 399       break;
 400     case SizerMaxNewSizeOnly:
 401       *min_young_length = calculate_default_min_length(number_of_heap_regions);
 402       *min_young_length = MIN2(*min_young_length, *max_young_length);
 403       break;
 404     case SizerMaxAndNewSize:
 405       // Do nothing. Values set on the command line, don't update them at runtime.
 406       break;
 407     case SizerNewRatio:
 408       *min_young_length = number_of_heap_regions / (NewRatio + 1);
 409       *max_young_length = *min_young_length;
 410       break;
 411     default:
 412       ShouldNotReachHere();
 413   }
 414 
 415   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");
 416 }
 417 
 418 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {
 419   // We need to pass the desired values because recalculation may not update these
 420   // values in some cases.
 421   uint temp = _min_desired_young_length;
 422   uint result = _max_desired_young_length;
 423   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);
 424   return result;
 425 }
 426 
 427 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 428   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,
 429           &_max_desired_young_length);
 430 }
 431 
 432 void G1CollectorPolicy::init() {
 433   // Set aside an initial future to_space.
 434   _g1 = G1CollectedHeap::heap();
 435 
 436   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 437 
 438   initialize_gc_policy_counters();
 439 
 440   if (adaptive_young_list_length()) {
 441     _young_list_fixed_length = 0;
 442   } else {
 443     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 444   }
 445   _free_regions_at_end_of_collection = _g1->num_free_regions();
 446 
 447   update_young_list_max_and_target_length();
 448   // We may immediately start allocating regions and placing them on the
 449   // collection set list. Initialize the per-collection set info
 450   start_incremental_cset_building();
 451 }
 452 
 453 void G1CollectorPolicy::note_gc_start(uint num_active_workers) {
 454   phase_times()->note_gc_start(num_active_workers);
 455 }
 456 
 457 // Create the jstat counters for the policy.
 458 void G1CollectorPolicy::initialize_gc_policy_counters() {
 459   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 460 }
 461 
 462 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 463                                          double base_time_ms,
 464                                          uint base_free_regions,
 465                                          double target_pause_time_ms) const {
 466   if (young_length >= base_free_regions) {
 467     // end condition 1: not enough space for the young regions
 468     return false;
 469   }
 470 
 471   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 472   size_t bytes_to_copy =
 473                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 474   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 475   double young_other_time_ms = predict_young_other_time_ms(young_length);
 476   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 477   if (pause_time_ms > target_pause_time_ms) {
 478     // end condition 2: prediction is over the target pause time
 479     return false;
 480   }
 481 
 482   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 483   if ((2.0 /* magic */ * _predictor.sigma()) * bytes_to_copy > free_bytes) {
 484     // end condition 3: out-of-space (conservatively!)
 485     return false;
 486   }
 487 
 488   // success!
 489   return true;
 490 }
 491 
 492 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 493   // re-calculate the necessary reserve
 494   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 495   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 496   // smaller than 1.0) we'll get 1.
 497   _reserve_regions = (uint) ceil(reserve_regions_d);
 498 
 499   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 500 }
 501 
 502 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 503                                                        uint base_min_length) const {
 504   uint desired_min_length = 0;
 505   if (adaptive_young_list_length()) {
 506     if (_alloc_rate_ms_seq->num() > 3) {
 507       double now_sec = os::elapsedTime();
 508       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 509       double alloc_rate_ms = predict_alloc_rate_ms();
 510       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 511     } else {
 512       // otherwise we don't have enough info to make the prediction
 513     }
 514   }
 515   desired_min_length += base_min_length;
 516   // make sure we don't go below any user-defined minimum bound
 517   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 518 }
 519 
 520 uint G1CollectorPolicy::calculate_young_list_desired_max_length() const {
 521   // Here, we might want to also take into account any additional
 522   // constraints (i.e., user-defined minimum bound). Currently, we
 523   // effectively don't set this bound.
 524   return _young_gen_sizer->max_desired_young_length();
 525 }
 526 
 527 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t* unbounded_target_length) {
 528   update_young_list_max_and_target_length(get_new_prediction(_rs_lengths_seq), unbounded_target_length);
 529 }
 530 
 531 void G1CollectorPolicy::update_young_list_max_and_target_length(size_t rs_lengths, size_t* unbounded_target_length) {
 532   update_young_list_target_length(rs_lengths, unbounded_target_length);
 533   update_max_gc_locker_expansion();
 534 }
 535 
 536 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths, size_t* unbounded_target_length) {
 537   _young_list_target_length = bounded_young_list_target_length(rs_lengths, unbounded_target_length);
 538 }
 539 
 540 void G1CollectorPolicy::update_young_list_target_length() {
 541   update_young_list_target_length(get_new_prediction(_rs_lengths_seq));
 542 }
 543 
 544 uint G1CollectorPolicy::bounded_young_list_target_length(size_t rs_lengths, size_t* unbounded_target_length) const {
 545   // Calculate the absolute and desired min bounds.
 546 
 547   // This is how many young regions we already have (currently: the survivors).
 548   uint base_min_length = recorded_survivor_regions();
 549   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 550   // This is the absolute minimum young length. Ensure that we
 551   // will at least have one eden region available for allocation.
 552   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 553   // If we shrank the young list target it should not shrink below the current size.
 554   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 555   // Calculate the absolute and desired max bounds.
 556 
 557   uint desired_max_length = calculate_young_list_desired_max_length();
 558 
 559   uint young_list_target_length = 0;
 560   if (adaptive_young_list_length()) {
 561     if (collector_state()->gcs_are_young()) {
 562       young_list_target_length =
 563                         calculate_young_list_target_length(rs_lengths,
 564                                                            base_min_length,
 565                                                            desired_min_length,
 566                                                            desired_max_length);
 567     } else {
 568       // Don't calculate anything and let the code below bound it to
 569       // the desired_min_length, i.e., do the next GC as soon as
 570       // possible to maximize how many old regions we can add to it.
 571     }
 572   } else {
 573     // The user asked for a fixed young gen so we'll fix the young gen
 574     // whether the next GC is young or mixed.
 575     young_list_target_length = _young_list_fixed_length;
 576   }
 577 
 578   if (unbounded_target_length != NULL) {
 579     *unbounded_target_length = young_list_target_length;    
 580   }
 581   
 582   // We will try our best not to "eat" into the reserve.
 583   uint absolute_max_length = 0;
 584   if (_free_regions_at_end_of_collection > _reserve_regions) {
 585     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 586   }
 587   if (desired_max_length > absolute_max_length) {
 588     desired_max_length = absolute_max_length;
 589   }
 590 
 591   // Make sure we don't go over the desired max length, nor under the
 592   // desired min length. In case they clash, desired_min_length wins
 593   // which is why that test is second.
 594   if (young_list_target_length > desired_max_length) {
 595     young_list_target_length = desired_max_length;
 596   }
 597   if (young_list_target_length < desired_min_length) {
 598     young_list_target_length = desired_min_length;
 599   }
 600 
 601   assert(young_list_target_length > recorded_survivor_regions(),
 602          "we should be able to allocate at least one eden region");
 603   assert(young_list_target_length >= absolute_min_length, "post-condition");
 604 
 605   return young_list_target_length;
 606 }
 607 
 608 uint
 609 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 610                                                      uint base_min_length,
 611                                                      uint desired_min_length,
 612                                                      uint desired_max_length) const {
 613   assert(adaptive_young_list_length(), "pre-condition");
 614   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 615 
 616   // In case some edge-condition makes the desired max length too small...
 617   if (desired_max_length <= desired_min_length) {
 618     return desired_min_length;
 619   }
 620 
 621   // We'll adjust min_young_length and max_young_length not to include
 622   // the already allocated young regions (i.e., so they reflect the
 623   // min and max eden regions we'll allocate). The base_min_length
 624   // will be reflected in the predictions by the
 625   // survivor_regions_evac_time prediction.
 626   assert(desired_min_length > base_min_length, "invariant");
 627   uint min_young_length = desired_min_length - base_min_length;
 628   assert(desired_max_length > base_min_length, "invariant");
 629   uint max_young_length = desired_max_length - base_min_length;
 630 
 631   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 632   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 633   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 634   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 635   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 636   double base_time_ms =
 637     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 638     survivor_regions_evac_time;
 639   uint available_free_regions = _free_regions_at_end_of_collection;
 640   uint base_free_regions = 0;
 641   if (available_free_regions > _reserve_regions) {
 642     base_free_regions = available_free_regions - _reserve_regions;
 643   }
 644 
 645   // Here, we will make sure that the shortest young length that
 646   // makes sense fits within the target pause time.
 647 
 648   if (predict_will_fit(min_young_length, base_time_ms,
 649                        base_free_regions, target_pause_time_ms)) {
 650     // The shortest young length will fit into the target pause time;
 651     // we'll now check whether the absolute maximum number of young
 652     // regions will fit in the target pause time. If not, we'll do
 653     // a binary search between min_young_length and max_young_length.
 654     if (predict_will_fit(max_young_length, base_time_ms,
 655                          base_free_regions, target_pause_time_ms)) {
 656       // The maximum young length will fit into the target pause time.
 657       // We are done so set min young length to the maximum length (as
 658       // the result is assumed to be returned in min_young_length).
 659       min_young_length = max_young_length;
 660     } else {
 661       // The maximum possible number of young regions will not fit within
 662       // the target pause time so we'll search for the optimal
 663       // length. The loop invariants are:
 664       //
 665       // min_young_length < max_young_length
 666       // min_young_length is known to fit into the target pause time
 667       // max_young_length is known not to fit into the target pause time
 668       //
 669       // Going into the loop we know the above hold as we've just
 670       // checked them. Every time around the loop we check whether
 671       // the middle value between min_young_length and
 672       // max_young_length fits into the target pause time. If it
 673       // does, it becomes the new min. If it doesn't, it becomes
 674       // the new max. This way we maintain the loop invariants.
 675 
 676       assert(min_young_length < max_young_length, "invariant");
 677       uint diff = (max_young_length - min_young_length) / 2;
 678       while (diff > 0) {
 679         uint young_length = min_young_length + diff;
 680         if (predict_will_fit(young_length, base_time_ms,
 681                              base_free_regions, target_pause_time_ms)) {
 682           min_young_length = young_length;
 683         } else {
 684           max_young_length = young_length;
 685         }
 686         assert(min_young_length <  max_young_length, "invariant");
 687         diff = (max_young_length - min_young_length) / 2;
 688       }
 689       // The results is min_young_length which, according to the
 690       // loop invariants, should fit within the target pause time.
 691 
 692       // These are the post-conditions of the binary search above:
 693       assert(min_young_length < max_young_length,
 694              "otherwise we should have discovered that max_young_length "
 695              "fits into the pause target and not done the binary search");
 696       assert(predict_will_fit(min_young_length, base_time_ms,
 697                               base_free_regions, target_pause_time_ms),
 698              "min_young_length, the result of the binary search, should "
 699              "fit into the pause target");
 700       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 701                                base_free_regions, target_pause_time_ms),
 702              "min_young_length, the result of the binary search, should be "
 703              "optimal, so no larger length should fit into the pause target");
 704     }
 705   } else {
 706     // Even the minimum length doesn't fit into the pause time
 707     // target, return it as the result nevertheless.
 708   }
 709   return base_min_length + min_young_length;
 710 }
 711 
 712 double G1CollectorPolicy::predict_survivor_regions_evac_time() const {
 713   double survivor_regions_evac_time = 0.0;
 714   for (HeapRegion * r = _recorded_survivor_head;
 715        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 716        r = r->get_next_young_region()) {
 717     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 718   }
 719   return survivor_regions_evac_time;
 720 }
 721 
 722 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 723   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 724 
 725   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 726   if (rs_lengths > _rs_lengths_prediction) {
 727     // add 10% to avoid having to recalculate often
 728     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 729     update_rs_lengths_prediction(rs_lengths_prediction);
 730 
 731     update_young_list_max_and_target_length(rs_lengths_prediction);
 732   }
 733 }
 734 
 735 void G1CollectorPolicy::update_rs_lengths_prediction() {
 736   update_rs_lengths_prediction(get_new_prediction(_rs_lengths_seq));
 737 }
 738 
 739 void G1CollectorPolicy::update_rs_lengths_prediction(size_t prediction) {
 740   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 741     _rs_lengths_prediction = prediction;
 742   }
 743 }
 744 
 745 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 746                                                bool is_tlab,
 747                                                bool* gc_overhead_limit_was_exceeded) {
 748   guarantee(false, "Not using this policy feature yet.");
 749   return NULL;
 750 }
 751 
 752 // This method controls how a collector handles one or more
 753 // of its generations being fully allocated.
 754 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 755                                                        bool is_tlab) {
 756   guarantee(false, "Not using this policy feature yet.");
 757   return NULL;
 758 }
 759 
 760 
 761 #ifndef PRODUCT
 762 bool G1CollectorPolicy::verify_young_ages() {
 763   HeapRegion* head = _g1->young_list()->first_region();
 764   return
 765     verify_young_ages(head, _short_lived_surv_rate_group);
 766   // also call verify_young_ages on any additional surv rate groups
 767 }
 768 
 769 bool
 770 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 771                                      SurvRateGroup *surv_rate_group) {
 772   guarantee( surv_rate_group != NULL, "pre-condition" );
 773 
 774   const char* name = surv_rate_group->name();
 775   bool ret = true;
 776   int prev_age = -1;
 777 
 778   for (HeapRegion* curr = head;
 779        curr != NULL;
 780        curr = curr->get_next_young_region()) {
 781     SurvRateGroup* group = curr->surv_rate_group();
 782     if (group == NULL && !curr->is_survivor()) {
 783       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
 784       ret = false;
 785     }
 786 
 787     if (surv_rate_group == group) {
 788       int age = curr->age_in_surv_rate_group();
 789 
 790       if (age < 0) {
 791         gclog_or_tty->print_cr("## %s: encountered negative age", name);
 792         ret = false;
 793       }
 794 
 795       if (age <= prev_age) {
 796         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
 797                                "(%d, %d)", name, age, prev_age);
 798         ret = false;
 799       }
 800       prev_age = age;
 801     }
 802   }
 803 
 804   return ret;
 805 }
 806 #endif // PRODUCT
 807 
 808 void G1CollectorPolicy::record_full_collection_start() {
 809   _full_collection_start_sec = os::elapsedTime();
 810   record_heap_size_info_at_start(true /* full */);
 811   // Release the future to-space so that it is available for compaction into.
 812   collector_state()->set_full_collection(true);
 813 }
 814 
 815 void G1CollectorPolicy::record_full_collection_end() {
 816   // Consider this like a collection pause for the purposes of allocation
 817   // since last pause.
 818   double end_sec = os::elapsedTime();
 819   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 820   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 821 
 822   _trace_old_gen_time_data.record_full_collection(full_gc_time_ms);
 823 
 824   update_recent_gc_times(end_sec, full_gc_time_ms);
 825 
 826   collector_state()->set_full_collection(false);
 827 
 828   // "Nuke" the heuristics that control the young/mixed GC
 829   // transitions and make sure we start with young GCs after the Full GC.
 830   collector_state()->set_gcs_are_young(true);
 831   collector_state()->set_last_young_gc(false);
 832   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 833   collector_state()->set_during_initial_mark_pause(false);
 834   collector_state()->set_in_marking_window(false);
 835   collector_state()->set_in_marking_window_im(false);
 836 
 837   _short_lived_surv_rate_group->start_adding_regions();
 838   // also call this on any additional surv rate groups
 839 
 840   record_survivor_regions(0, NULL, NULL);
 841 
 842   _free_regions_at_end_of_collection = _g1->num_free_regions();
 843   // Reset survivors SurvRateGroup.
 844   _survivor_surv_rate_group->reset();
 845   update_young_list_max_and_target_length();
 846   update_rs_lengths_prediction();
 847   _collectionSetChooser->clear();
 848 
 849   _last_old_allocated_bytes = 0;
 850 
 851   record_pause(FullGC, _full_collection_start_sec, end_sec);
 852 }
 853 
 854 void G1CollectorPolicy::record_stop_world_start() {
 855   _stop_world_start = os::elapsedTime();
 856 }
 857 
 858 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
 859   // We only need to do this here as the policy will only be applied
 860   // to the GC we're about to start. so, no point is calculating this
 861   // every time we calculate / recalculate the target young length.
 862   update_survivors_policy();
 863 
 864   assert(_g1->used() == _g1->recalculate_used(),
 865          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 866          _g1->used(), _g1->recalculate_used());
 867 
 868   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 869   _trace_young_gen_time_data.record_start_collection(s_w_t_ms);
 870   _stop_world_start = 0.0;
 871 
 872   record_heap_size_info_at_start(false /* full */);
 873 
 874   phase_times()->record_cur_collection_start_sec(start_time_sec);
 875   _pending_cards = _g1->pending_card_num();
 876 
 877   _collection_set_bytes_used_before = 0;
 878   _bytes_copied_during_gc = 0;
 879 
 880   collector_state()->set_last_gc_was_young(false);
 881 
 882   // do that for any other surv rate groups
 883   _short_lived_surv_rate_group->stop_adding_regions();
 884   _survivors_age_table.clear();
 885 
 886   assert( verify_young_ages(), "region age verification" );
 887 }
 888 
 889 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 890                                                    mark_init_elapsed_time_ms) {
 891   collector_state()->set_during_marking(true);
 892   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 893   collector_state()->set_during_initial_mark_pause(false);
 894   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 895 }
 896 
 897 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 898   _mark_remark_start_sec = os::elapsedTime();
 899   collector_state()->set_during_marking(false);
 900 }
 901 
 902 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 903   double end_time_sec = os::elapsedTime();
 904   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 905   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 906   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 907   _prev_collection_pause_end_ms += elapsed_time_ms;
 908 
 909   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 910 }
 911 
 912 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 913   _mark_cleanup_start_sec = os::elapsedTime();
 914 }
 915 
 916 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 917   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 918                                                               "skip last young-only gc");
 919   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 920   // We abort the marking phase.
 921   if (!should_continue_with_reclaim) {
 922     abort_time_to_mixed_tracking();
 923   }
 924   collector_state()->set_in_marking_window(false);
 925 }
 926 
 927 void G1CollectorPolicy::record_concurrent_pause() {
 928   if (_stop_world_start > 0.0) {
 929     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 930     _trace_young_gen_time_data.record_yield_time(yield_ms);
 931   }
 932 }
 933 
 934 double G1CollectorPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 935   return phase_times()->average_time_ms(phase);
 936 }
 937 
 938 double G1CollectorPolicy::young_other_time_ms() const {
 939   return phase_times()->young_cset_choice_time_ms() +
 940          phase_times()->young_free_cset_time_ms();
 941 }
 942 
 943 double G1CollectorPolicy::non_young_other_time_ms() const {
 944   return phase_times()->non_young_cset_choice_time_ms() +
 945          phase_times()->non_young_free_cset_time_ms();
 946 
 947 }
 948 
 949 double G1CollectorPolicy::other_time_ms(double pause_time_ms) const {
 950   return pause_time_ms -
 951          average_time_ms(G1GCPhaseTimes::UpdateRS) -
 952          average_time_ms(G1GCPhaseTimes::ScanRS) -
 953          average_time_ms(G1GCPhaseTimes::ObjCopy) -
 954          average_time_ms(G1GCPhaseTimes::Termination);
 955 }
 956 
 957 double G1CollectorPolicy::constant_other_time_ms(double pause_time_ms) const {
 958   return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
 959 }
 960 
 961 bool G1CollectorPolicy::about_to_start_mixed_phase() const {
 962   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 963 }
 964 
 965 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 966   if (about_to_start_mixed_phase()) {
 967     return false;
 968   }
 969 
 970   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 971 
 972   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 973   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 974   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 975 
 976   if (marking_request_bytes > marking_initiating_used_threshold) {
 977     if (collector_state()->gcs_are_young() && !collector_state()->last_young_gc()) {
 978       ergo_verbose5(ErgoConcCycles,
 979         "request concurrent cycle initiation",
 980         ergo_format_reason("occupancy higher than threshold")
 981         ergo_format_byte("occupancy")
 982         ergo_format_byte("allocation request")
 983         ergo_format_byte_perc("threshold")
 984         ergo_format_str("source"),
 985         cur_used_bytes,
 986         alloc_byte_size,
 987         marking_initiating_used_threshold,
 988         (double) marking_initiating_used_threshold / _g1->capacity() * 100,
 989         source);
 990       return true;
 991     } else {
 992       ergo_verbose5(ErgoConcCycles,
 993         "do not request concurrent cycle initiation",
 994         ergo_format_reason("still doing mixed collections")
 995         ergo_format_byte("occupancy")
 996         ergo_format_byte("allocation request")
 997         ergo_format_byte_perc("threshold")
 998         ergo_format_str("source"),
 999         cur_used_bytes,
1000         alloc_byte_size,
1001         marking_initiating_used_threshold,
1002         (double) InitiatingHeapOccupancyPercent,
1003         source);
1004     }
1005   }
1006 
1007   return false;
1008 }
1009 
1010 // Anything below that is considered to be zero
1011 #define MIN_TIMER_GRANULARITY 0.0000001
1012 
1013 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned) {
1014   double end_time_sec = os::elapsedTime();
1015   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
1016          "otherwise, the subtraction below does not make sense");
1017   size_t cur_used_bytes = _g1->used();
1018   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
1019   bool last_pause_included_initial_mark = false;
1020   bool update_stats = !_g1->evacuation_failed();
1021 
1022 #ifndef PRODUCT
1023   if (G1YoungSurvRateVerbose) {
1024     gclog_or_tty->cr();
1025     _short_lived_surv_rate_group->print();
1026     // do that for any other surv rate groups too
1027   }
1028 #endif // PRODUCT
1029 
1030   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
1031 
1032   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
1033   if (last_pause_included_initial_mark) {
1034     record_concurrent_mark_init_end(0.0);
1035   } else {
1036     maybe_start_marking();
1037   }
1038 
1039   double app_time_ms = 1.0;
1040 
1041   if (update_stats) {
1042     _trace_young_gen_time_data.record_end_collection(pause_time_ms, phase_times());
1043     // this is where we update the allocation rate of the application
1044     app_time_ms =
1045       (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
1046     if (app_time_ms < MIN_TIMER_GRANULARITY) {
1047       // This usually happens due to the timer not having the required
1048       // granularity. Some Linuxes are the usual culprits.
1049       // We'll just set it to something (arbitrarily) small.
1050       app_time_ms = 1.0;
1051     }
1052     // We maintain the invariant that all objects allocated by mutator
1053     // threads will be allocated out of eden regions. So, we can use
1054     // the eden region number allocated since the previous GC to
1055     // calculate the application's allocate rate. The only exception
1056     // to that is humongous objects that are allocated separately. But
1057     // given that humongous object allocations do not really affect
1058     // either the pause's duration nor when the next pause will take
1059     // place we can safely ignore them here.
1060     uint regions_allocated = eden_cset_region_length();
1061     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
1062     _alloc_rate_ms_seq->add(alloc_rate_ms);
1063 
1064     double interval_ms =
1065       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
1066     update_recent_gc_times(end_time_sec, pause_time_ms);
1067     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
1068     if (recent_avg_pause_time_ratio() < 0.0 ||
1069         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
1070 #ifndef PRODUCT
1071       // Dump info to allow post-facto debugging
1072       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
1073       gclog_or_tty->print_cr("-------------------------------------------");
1074       gclog_or_tty->print_cr("Recent GC Times (ms):");
1075       _recent_gc_times_ms->dump();
1076       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
1077       _recent_prev_end_times_for_all_gcs_sec->dump();
1078       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
1079                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
1080       // In debug mode, terminate the JVM if the user wants to debug at this point.
1081       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1082 #endif  // !PRODUCT
1083       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1084       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1085       if (_recent_avg_pause_time_ratio < 0.0) {
1086         _recent_avg_pause_time_ratio = 0.0;
1087       } else {
1088         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1089         _recent_avg_pause_time_ratio = 1.0;
1090       }
1091     }
1092   }
1093 
1094   bool new_in_marking_window = collector_state()->in_marking_window();
1095   bool new_in_marking_window_im = false;
1096   if (last_pause_included_initial_mark) {
1097     new_in_marking_window = true;
1098     new_in_marking_window_im = true;
1099   }
1100 
1101   if (collector_state()->last_young_gc()) {
1102     // This is supposed to to be the "last young GC" before we start
1103     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1104     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
1105 
1106     if (next_gc_should_be_mixed("start mixed GCs",
1107                                 "do not start mixed GCs")) {
1108       collector_state()->set_gcs_are_young(false);
1109     } else {
1110       // We aborted the mixed GC phase early.
1111       abort_time_to_mixed_tracking();
1112     }
1113 
1114     collector_state()->set_last_young_gc(false);
1115   }
1116 
1117   if (!collector_state()->last_gc_was_young()) {
1118     // This is a mixed GC. Here we decide whether to continue doing
1119     // mixed GCs or not.
1120     if (!next_gc_should_be_mixed("continue mixed GCs",
1121                                  "do not continue mixed GCs")) {
1122       collector_state()->set_gcs_are_young(true);
1123 
1124       maybe_start_marking();
1125     }
1126   }
1127 
1128   _short_lived_surv_rate_group->start_adding_regions();
1129   // Do that for any other surv rate groups
1130 
1131   if (update_stats) {
1132     double cost_per_card_ms = 0.0;
1133     double cost_scan_hcc = average_time_ms(G1GCPhaseTimes::ScanHCC);
1134     if (_pending_cards > 0) {
1135       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - cost_scan_hcc) / (double) _pending_cards;
1136       _cost_per_card_ms_seq->add(cost_per_card_ms);
1137     }
1138     _cost_scan_hcc_seq->add(cost_scan_hcc);
1139 
1140     double cost_per_entry_ms = 0.0;
1141     if (cards_scanned > 10) {
1142       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
1143       if (collector_state()->last_gc_was_young()) {
1144         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1145       } else {
1146         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1147       }
1148     }
1149 
1150     if (_max_rs_lengths > 0) {
1151       double cards_per_entry_ratio =
1152         (double) cards_scanned / (double) _max_rs_lengths;
1153       if (collector_state()->last_gc_was_young()) {
1154         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1155       } else {
1156         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1157       }
1158     }
1159 
1160     // This is defensive. For a while _max_rs_lengths could get
1161     // smaller than _recorded_rs_lengths which was causing
1162     // rs_length_diff to get very large and mess up the RSet length
1163     // predictions. The reason was unsafe concurrent updates to the
1164     // _inc_cset_recorded_rs_lengths field which the code below guards
1165     // against (see CR 7118202). This bug has now been fixed (see CR
1166     // 7119027). However, I'm still worried that
1167     // _inc_cset_recorded_rs_lengths might still end up somewhat
1168     // inaccurate. The concurrent refinement thread calculates an
1169     // RSet's length concurrently with other CR threads updating it
1170     // which might cause it to calculate the length incorrectly (if,
1171     // say, it's in mid-coarsening). So I'll leave in the defensive
1172     // conditional below just in case.
1173     size_t rs_length_diff = 0;
1174     if (_max_rs_lengths > _recorded_rs_lengths) {
1175       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1176     }
1177     _rs_length_diff_seq->add((double) rs_length_diff);
1178 
1179     size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;
1180     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;
1181     double cost_per_byte_ms = 0.0;
1182 
1183     if (copied_bytes > 0) {
1184       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
1185       if (collector_state()->in_marking_window()) {
1186         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1187       } else {
1188         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1189       }
1190     }
1191 
1192     if (young_cset_region_length() > 0) {
1193       _young_other_cost_per_region_ms_seq->add(young_other_time_ms() /
1194                                                young_cset_region_length());
1195     }
1196 
1197     if (old_cset_region_length() > 0) {
1198       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms() /
1199                                                    old_cset_region_length());
1200     }
1201 
1202     _constant_other_time_ms_seq->add(constant_other_time_ms(pause_time_ms));
1203 
1204     _pending_cards_seq->add((double) _pending_cards);
1205     _rs_lengths_seq->add((double) _max_rs_lengths);
1206   }
1207 
1208   collector_state()->set_in_marking_window(new_in_marking_window);
1209   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
1210   _free_regions_at_end_of_collection = _g1->num_free_regions();
1211   // IHOP control wants to know the expected young gen length if it were not
1212   // restrained by the heap reserve. Using the actual length would make the
1213   // prediction too small and the limit the young gen every time we get to the
1214   // predicted target occupancy.
1215   size_t last_unrestrained_young_length = 0;
1216   update_young_list_max_and_target_length(&last_unrestrained_young_length);
1217   update_rs_lengths_prediction();
1218 
1219   double marking_to_mixed_time = -1.0;
1220   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
1221     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
1222     assert(marking_to_mixed_time > 0.0,
1223            "Initial mark to mixed time must be larger than zero but is %.3f",
1224            marking_to_mixed_time);
1225   }
1226   // Only update IHOP information on regular GCs.
1227   if (update_stats) {
1228     update_ihop_statistics(marking_to_mixed_time,
1229                            app_time_ms / 1000.0,
1230                            _last_old_allocated_bytes,
1231                            last_unrestrained_young_length * HeapRegion::GrainBytes);
1232   }
1233   _last_old_allocated_bytes = 0;
1234 
1235   _ihop_control->send_jfr_event(_g1->gc_tracer_stw());
1236 
1237   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1238   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1239 
1240   double scan_hcc_time_ms = average_time_ms(G1GCPhaseTimes::ScanHCC);
1241 
1242   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
1243     ergo_verbose2(ErgoTiming,
1244                   "adjust concurrent refinement thresholds",
1245                   ergo_format_reason("Scanning the HCC expected to take longer than Update RS time goal")
1246                   ergo_format_ms("Update RS time goal")
1247                   ergo_format_ms("Scan HCC time"),
1248                   update_rs_time_goal_ms,
1249                   scan_hcc_time_ms);
1250 
1251     update_rs_time_goal_ms = 0;
1252   } else {
1253     update_rs_time_goal_ms -= scan_hcc_time_ms;
1254   }
1255   adjust_concurrent_refinement(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
1256                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
1257                                update_rs_time_goal_ms);
1258 
1259   _collectionSetChooser->verify();
1260 }
1261 
1262 G1IHOPControl* G1CollectorPolicy::create_ihop_control() const {
1263   if (G1UseAdaptiveIHOP) {
1264     // The target occupancy is the total heap occupancy we want to hit. First, we
1265     // want to avoid eating into the reserve intended for young GC (to avoid unnecessary
1266     // throughput loss). Additionally G1 is free to not clean out up to
1267     // G1HeapWastePercent of heap, that space also cannot be used for allocation
1268     // while marking.
1269     size_t safe_heap_percentage = (size_t) (G1ReservePercent + G1HeapWastePercent);
1270     size_t target_occupancy = 0;
1271 
1272     if (safe_heap_percentage < 100) {
1273       target_occupancy = G1CollectedHeap::heap()->max_capacity() * (100.0 - safe_heap_percentage) / 100.0;
1274     }
1275     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
1276                                      target_occupancy,
1277                                      &_predictor);
1278   } else {
1279     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent,
1280                                    G1CollectedHeap::heap()->max_capacity());
1281   }
1282 }
1283 
1284 void G1CollectorPolicy::update_ihop_statistics(double marking_time,
1285                                                double mutator_time_s,
1286                                                size_t mutator_alloc_bytes,
1287                                                size_t young_gen_size) {
1288   bool report = false;
1289 
1290   // To avoid using really small times that may be caused by e.g. back-to-back gcs
1291   // we filter them out.
1292   double const min_valid_time = 1e-6;
1293 
1294   if (marking_time > min_valid_time) {
1295     _ihop_control->update_time_to_mixed(marking_time);
1296     report = true;
1297   }
1298 
1299   // As an approximation for the young gc promotion rates during marking we use
1300   // all of them. In many applications there are only a few if any young gcs during
1301   // marking, which makes any prediction useless. This increases the accuracy of the
1302   // prediction.
1303   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
1304     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
1305     report = true;
1306   }
1307 
1308   if (report) {
1309     report_ihop_statistics();
1310   }
1311 }
1312 
1313 void G1CollectorPolicy::report_ihop_statistics() {
1314   _ihop_control->print();
1315 }
1316 
1317 #define EXT_SIZE_FORMAT "%.1f%s"
1318 #define EXT_SIZE_PARAMS(bytes)                                  \
1319   byte_size_in_proper_unit((double)(bytes)),                    \
1320   proper_unit_for_byte_size((bytes))
1321 
1322 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {
1323   YoungList* young_list = _g1->young_list();
1324   _eden_used_bytes_before_gc = young_list->eden_used_bytes();
1325   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
1326   _heap_capacity_bytes_before_gc = _g1->capacity();
1327   _heap_used_bytes_before_gc = _g1->used();
1328   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
1329 
1330   _eden_capacity_bytes_before_gc =
1331          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
1332 
1333   if (full) {
1334     _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();
1335   }
1336 }
1337 
1338 void G1CollectorPolicy::print_heap_transition(size_t bytes_before) const {
1339   size_t bytes_after = _g1->used();
1340   size_t capacity = _g1->capacity();
1341 
1342   gclog_or_tty->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
1343       byte_size_in_proper_unit(bytes_before),
1344       proper_unit_for_byte_size(bytes_before),
1345       byte_size_in_proper_unit(bytes_after),
1346       proper_unit_for_byte_size(bytes_after),
1347       byte_size_in_proper_unit(capacity),
1348       proper_unit_for_byte_size(capacity));
1349 }
1350 
1351 void G1CollectorPolicy::print_heap_transition() const {
1352   print_heap_transition(_heap_used_bytes_before_gc);
1353 }
1354 
1355 void G1CollectorPolicy::print_detailed_heap_transition(bool full) const {
1356   YoungList* young_list = _g1->young_list();
1357 
1358   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();
1359   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();
1360   size_t heap_used_bytes_after_gc = _g1->used();
1361 
1362   size_t heap_capacity_bytes_after_gc = _g1->capacity();
1363   size_t eden_capacity_bytes_after_gc =
1364     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;
1365 
1366   gclog_or_tty->print(
1367     "   [Eden: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->" EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ") "
1368     "Survivors: " EXT_SIZE_FORMAT "->" EXT_SIZE_FORMAT " "
1369     "Heap: " EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")->"
1370     EXT_SIZE_FORMAT "(" EXT_SIZE_FORMAT ")]",
1371     EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),
1372     EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),
1373     EXT_SIZE_PARAMS(eden_used_bytes_after_gc),
1374     EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),
1375     EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),
1376     EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),
1377     EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),
1378     EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),
1379     EXT_SIZE_PARAMS(heap_used_bytes_after_gc),
1380     EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));
1381 
1382   if (full) {
1383     MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);
1384   }
1385 
1386   gclog_or_tty->cr();
1387 }
1388 
1389 void G1CollectorPolicy::print_phases(double pause_time_sec) {
1390   phase_times()->print(pause_time_sec);
1391 }
1392 
1393 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1394                                                      double update_rs_processed_buffers,
1395                                                      double goal_ms) {
1396   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1397   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1398 
1399   if (G1UseAdaptiveConcRefinement) {
1400     const int k_gy = 3, k_gr = 6;
1401     const double inc_k = 1.1, dec_k = 0.9;
1402 
1403     int g = cg1r->green_zone();
1404     if (update_rs_time > goal_ms) {
1405       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1406     } else {
1407       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1408         g = (int)MAX2(g * inc_k, g + 1.0);
1409       }
1410     }
1411     // Change the refinement threads params
1412     cg1r->set_green_zone(g);
1413     cg1r->set_yellow_zone(g * k_gy);
1414     cg1r->set_red_zone(g * k_gr);
1415     cg1r->reinitialize_threads();
1416 
1417     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * _predictor.sigma()), 1);
1418     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1419                                     cg1r->yellow_zone());
1420     // Change the barrier params
1421     dcqs.set_process_completed_threshold(processing_threshold);
1422     dcqs.set_max_completed_queue(cg1r->red_zone());
1423   }
1424 
1425   int curr_queue_size = dcqs.completed_buffers_num();
1426   if (curr_queue_size >= cg1r->yellow_zone()) {
1427     dcqs.set_completed_queue_padding(curr_queue_size);
1428   } else {
1429     dcqs.set_completed_queue_padding(0);
1430   }
1431   dcqs.notify_if_necessary();
1432 }
1433 
1434 size_t G1CollectorPolicy::predict_rs_length_diff() const {
1435   return (size_t) get_new_prediction(_rs_length_diff_seq);
1436 }
1437 
1438 double G1CollectorPolicy::predict_alloc_rate_ms() const {
1439   return get_new_prediction(_alloc_rate_ms_seq);
1440 }
1441 
1442 double G1CollectorPolicy::predict_cost_per_card_ms() const {
1443   return get_new_prediction(_cost_per_card_ms_seq);
1444 }
1445 
1446 double G1CollectorPolicy::predict_scan_hcc_ms() const {
1447   return get_new_prediction(_cost_scan_hcc_seq);
1448 }
1449 
1450 double G1CollectorPolicy::predict_rs_update_time_ms(size_t pending_cards) const {
1451   return pending_cards * predict_cost_per_card_ms() + predict_scan_hcc_ms();
1452 }
1453 
1454 double G1CollectorPolicy::predict_young_cards_per_entry_ratio() const {
1455   return get_new_prediction(_young_cards_per_entry_ratio_seq);
1456 }
1457 
1458 double G1CollectorPolicy::predict_mixed_cards_per_entry_ratio() const {
1459   if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
1460     return predict_young_cards_per_entry_ratio();
1461   } else {
1462     return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
1463   }
1464 }
1465 
1466 size_t G1CollectorPolicy::predict_young_card_num(size_t rs_length) const {
1467   return (size_t) (rs_length * predict_young_cards_per_entry_ratio());
1468 }
1469 
1470 size_t G1CollectorPolicy::predict_non_young_card_num(size_t rs_length) const {
1471   return (size_t)(rs_length * predict_mixed_cards_per_entry_ratio());
1472 }
1473 
1474 double G1CollectorPolicy::predict_rs_scan_time_ms(size_t card_num) const {
1475   if (collector_state()->gcs_are_young()) {
1476     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1477   } else {
1478     return predict_mixed_rs_scan_time_ms(card_num);
1479   }
1480 }
1481 
1482 double G1CollectorPolicy::predict_mixed_rs_scan_time_ms(size_t card_num) const {
1483   if (_mixed_cost_per_entry_ms_seq->num() < 3) {
1484     return card_num * get_new_prediction(_cost_per_entry_ms_seq);
1485   } else {
1486     return card_num * get_new_prediction(_mixed_cost_per_entry_ms_seq);
1487   }
1488 }
1489 
1490 double G1CollectorPolicy::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
1491   if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
1492     return (1.1 * bytes_to_copy) * get_new_prediction(_cost_per_byte_ms_seq);
1493   } else {
1494     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);
1495   }
1496 }
1497 
1498 double G1CollectorPolicy::predict_object_copy_time_ms(size_t bytes_to_copy) const {
1499   if (collector_state()->during_concurrent_mark()) {
1500     return predict_object_copy_time_ms_during_cm(bytes_to_copy);
1501   } else {
1502     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_seq);
1503   }
1504 }
1505 
1506 double G1CollectorPolicy::predict_constant_other_time_ms() const {
1507   return get_new_prediction(_constant_other_time_ms_seq);
1508 }
1509 
1510 double G1CollectorPolicy::predict_young_other_time_ms(size_t young_num) const {
1511   return young_num * get_new_prediction(_young_other_cost_per_region_ms_seq);
1512 }
1513 
1514 double G1CollectorPolicy::predict_non_young_other_time_ms(size_t non_young_num) const {
1515   return non_young_num * get_new_prediction(_non_young_other_cost_per_region_ms_seq);
1516 }
1517 
1518 double G1CollectorPolicy::predict_remark_time_ms() const {
1519   return get_new_prediction(_concurrent_mark_remark_times_ms);
1520 }
1521 
1522 double G1CollectorPolicy::predict_cleanup_time_ms() const {
1523   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
1524 }
1525 
1526 double G1CollectorPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
1527   TruncatedSeq* seq = surv_rate_group->get_seq(age);
1528   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
1529   double pred = get_new_prediction(seq);
1530   if (pred > 1.0) {
1531     pred = 1.0;
1532   }
1533   return pred;
1534 }
1535 
1536 double G1CollectorPolicy::predict_yg_surv_rate(int age) const {
1537   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
1538 }
1539 
1540 double G1CollectorPolicy::accum_yg_surv_rate_pred(int age) const {
1541   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
1542 }
1543 
1544 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1545                                                        size_t scanned_cards) const {
1546   return
1547     predict_rs_update_time_ms(pending_cards) +
1548     predict_rs_scan_time_ms(scanned_cards) +
1549     predict_constant_other_time_ms();
1550 }
1551 
1552 double G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
1553   size_t rs_length = predict_rs_length_diff();
1554   size_t card_num;
1555   if (collector_state()->gcs_are_young()) {
1556     card_num = predict_young_card_num(rs_length);
1557   } else {
1558     card_num = predict_non_young_card_num(rs_length);
1559   }
1560   return predict_base_elapsed_time_ms(pending_cards, card_num);
1561 }
1562 
1563 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
1564   size_t bytes_to_copy;
1565   if (hr->is_marked())
1566     bytes_to_copy = hr->max_live_bytes();
1567   else {
1568     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1569     int age = hr->age_in_surv_rate_group();
1570     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1571     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
1572   }
1573   return bytes_to_copy;
1574 }
1575 
1576 double G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1577                                                          bool for_young_gc) const {
1578   size_t rs_length = hr->rem_set()->occupied();
1579   size_t card_num;
1580 
1581   // Predicting the number of cards is based on which type of GC
1582   // we're predicting for.
1583   if (for_young_gc) {
1584     card_num = predict_young_card_num(rs_length);
1585   } else {
1586     card_num = predict_non_young_card_num(rs_length);
1587   }
1588   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1589 
1590   double region_elapsed_time_ms =
1591     predict_rs_scan_time_ms(card_num) +
1592     predict_object_copy_time_ms(bytes_to_copy);
1593 
1594   // The prediction of the "other" time for this region is based
1595   // upon the region type and NOT the GC type.
1596   if (hr->is_young()) {
1597     region_elapsed_time_ms += predict_young_other_time_ms(1);
1598   } else {
1599     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1600   }
1601   return region_elapsed_time_ms;
1602 }
1603 
1604 void G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1605                                                  uint survivor_cset_region_length) {
1606   _eden_cset_region_length     = eden_cset_region_length;
1607   _survivor_cset_region_length = survivor_cset_region_length;
1608   _old_cset_region_length      = 0;
1609 }
1610 
1611 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1612   _recorded_rs_lengths = rs_lengths;
1613 }
1614 
1615 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1616                                                double elapsed_ms) {
1617   _recent_gc_times_ms->add(elapsed_ms);
1618   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1619   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1620 }
1621 
1622 size_t G1CollectorPolicy::expansion_amount() const {
1623   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1624   double threshold = _gc_overhead_perc;
1625   if (recent_gc_overhead > threshold) {
1626     // We will double the existing space, or take
1627     // G1ExpandByPercentOfAvailable % of the available expansion
1628     // space, whichever is smaller, bounded below by a minimum
1629     // expansion (unless that's all that's left.)
1630     const size_t min_expand_bytes = 1*M;
1631     size_t reserved_bytes = _g1->max_capacity();
1632     size_t committed_bytes = _g1->capacity();
1633     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1634     size_t expand_bytes;
1635     size_t expand_bytes_via_pct =
1636       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1637     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1638     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1639     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1640 
1641     ergo_verbose5(ErgoHeapSizing,
1642                   "attempt heap expansion",
1643                   ergo_format_reason("recent GC overhead higher than "
1644                                      "threshold after GC")
1645                   ergo_format_perc("recent GC overhead")
1646                   ergo_format_perc("threshold")
1647                   ergo_format_byte("uncommitted")
1648                   ergo_format_byte_perc("calculated expansion amount"),
1649                   recent_gc_overhead, threshold,
1650                   uncommitted_bytes,
1651                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1652 
1653     return expand_bytes;
1654   } else {
1655     return 0;
1656   }
1657 }
1658 
1659 void G1CollectorPolicy::print_tracing_info() const {
1660   _trace_young_gen_time_data.print();
1661   _trace_old_gen_time_data.print();
1662 }
1663 
1664 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1665 #ifndef PRODUCT
1666   _short_lived_surv_rate_group->print_surv_rate_summary();
1667   // add this call for any other surv rate groups
1668 #endif // PRODUCT
1669 }
1670 
1671 bool G1CollectorPolicy::is_young_list_full() const {
1672   uint young_list_length = _g1->young_list()->length();
1673   uint young_list_target_length = _young_list_target_length;
1674   return young_list_length >= young_list_target_length;
1675 }
1676 
1677 bool G1CollectorPolicy::can_expand_young_list() const {
1678   uint young_list_length = _g1->young_list()->length();
1679   uint young_list_max_length = _young_list_max_length;
1680   return young_list_length < young_list_max_length;
1681 }
1682 
1683 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1684   uint expansion_region_num = 0;
1685   if (GCLockerEdenExpansionPercent > 0) {
1686     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1687     double expansion_region_num_d = perc * (double) _young_list_target_length;
1688     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1689     // less than 1.0) we'll get 1.
1690     expansion_region_num = (uint) ceil(expansion_region_num_d);
1691   } else {
1692     assert(expansion_region_num == 0, "sanity");
1693   }
1694   _young_list_max_length = _young_list_target_length + expansion_region_num;
1695   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1696 }
1697 
1698 // Calculates survivor space parameters.
1699 void G1CollectorPolicy::update_survivors_policy() {
1700   double max_survivor_regions_d =
1701                  (double) _young_list_target_length / (double) SurvivorRatio;
1702   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1703   // smaller than 1.0) we'll get 1.
1704   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1705 
1706   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1707         HeapRegion::GrainWords * _max_survivor_regions, counters());
1708 }
1709 
1710 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
1711   // We actually check whether we are marking here and not if we are in a
1712   // reclamation phase. This means that we will schedule a concurrent mark
1713   // even while we are still in the process of reclaiming memory.
1714   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1715   if (!during_cycle) {
1716     ergo_verbose1(ErgoConcCycles,
1717                   "request concurrent cycle initiation",
1718                   ergo_format_reason("requested by GC cause")
1719                   ergo_format_str("GC cause"),
1720                   GCCause::to_string(gc_cause));
1721     collector_state()->set_initiate_conc_mark_if_possible(true);
1722     return true;
1723   } else {
1724     ergo_verbose1(ErgoConcCycles,
1725                   "do not request concurrent cycle initiation",
1726                   ergo_format_reason("concurrent cycle already in progress")
1727                   ergo_format_str("GC cause"),
1728                   GCCause::to_string(gc_cause));
1729     return false;
1730   }
1731 }
1732 
1733 void G1CollectorPolicy::decide_on_conc_mark_initiation() {
1734   // We are about to decide on whether this pause will be an
1735   // initial-mark pause.
1736 
1737   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1738   // will set it here if we have to. However, it should be cleared by
1739   // the end of the pause (it's only set for the duration of an
1740   // initial-mark pause).
1741   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1742 
1743   if (collector_state()->initiate_conc_mark_if_possible()) {
1744     // We had noticed on a previous pause that the heap occupancy has
1745     // gone over the initiating threshold and we should start a
1746     // concurrent marking cycle. So we might initiate one.
1747 
1748     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1749       // Initiate a new initial mark only if there is no marking or reclamation going
1750       // on.
1751 
1752       collector_state()->set_during_initial_mark_pause(true);
1753       // And we can now clear initiate_conc_mark_if_possible() as
1754       // we've already acted on it.
1755       collector_state()->set_initiate_conc_mark_if_possible(false);
1756 
1757       ergo_verbose0(ErgoConcCycles,
1758                   "initiate concurrent cycle",
1759                   ergo_format_reason("concurrent cycle initiation requested"));
1760     } else {
1761       // The concurrent marking thread is still finishing up the
1762       // previous cycle. If we start one right now the two cycles
1763       // overlap. In particular, the concurrent marking thread might
1764       // be in the process of clearing the next marking bitmap (which
1765       // we will use for the next cycle if we start one). Starting a
1766       // cycle now will be bad given that parts of the marking
1767       // information might get cleared by the marking thread. And we
1768       // cannot wait for the marking thread to finish the cycle as it
1769       // periodically yields while clearing the next marking bitmap
1770       // and, if it's in a yield point, it's waiting for us to
1771       // finish. So, at this point we will not start a cycle and we'll
1772       // let the concurrent marking thread complete the last one.
1773       ergo_verbose0(ErgoConcCycles,
1774                     "do not initiate concurrent cycle",
1775                     ergo_format_reason("concurrent cycle already in progress"));
1776     }
1777   }
1778 }
1779 
1780 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1781   G1CollectedHeap* _g1h;
1782   CSetChooserParUpdater _cset_updater;
1783 
1784 public:
1785   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1786                            uint chunk_size) :
1787     _g1h(G1CollectedHeap::heap()),
1788     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1789 
1790   bool doHeapRegion(HeapRegion* r) {
1791     // Do we have any marking information for this region?
1792     if (r->is_marked()) {
1793       // We will skip any region that's currently used as an old GC
1794       // alloc region (we should not consider those for collection
1795       // before we fill them up).
1796       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1797         _cset_updater.add_region(r);
1798       }
1799     }
1800     return false;
1801   }
1802 };
1803 
1804 class ParKnownGarbageTask: public AbstractGangTask {
1805   CollectionSetChooser* _hrSorted;
1806   uint _chunk_size;
1807   G1CollectedHeap* _g1;
1808   HeapRegionClaimer _hrclaimer;
1809 
1810 public:
1811   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size, uint n_workers) :
1812       AbstractGangTask("ParKnownGarbageTask"),
1813       _hrSorted(hrSorted), _chunk_size(chunk_size),
1814       _g1(G1CollectedHeap::heap()), _hrclaimer(n_workers) {}
1815 
1816   void work(uint worker_id) {
1817     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1818     _g1->heap_region_par_iterate(&parKnownGarbageCl, worker_id, &_hrclaimer);
1819   }
1820 };
1821 
1822 uint G1CollectorPolicy::calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const {
1823   assert(n_workers > 0, "Active gc workers should be greater than 0");
1824   const uint overpartition_factor = 4;
1825   const uint min_chunk_size = MAX2(n_regions / n_workers, 1U);
1826   return MAX2(n_regions / (n_workers * overpartition_factor), min_chunk_size);
1827 }
1828 
1829 void G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
1830   _collectionSetChooser->clear();
1831 
1832   WorkGang* workers = _g1->workers();
1833   uint n_workers = workers->active_workers();
1834 
1835   uint n_regions = _g1->num_regions();
1836   uint chunk_size = calculate_parallel_work_chunk_size(n_workers, n_regions);
1837   _collectionSetChooser->prepare_for_par_region_addition(n_workers, n_regions, chunk_size);
1838   ParKnownGarbageTask par_known_garbage_task(_collectionSetChooser, chunk_size, n_workers);
1839   workers->run_task(&par_known_garbage_task);
1840 
1841   _collectionSetChooser->sort_regions();
1842 
1843   double end_sec = os::elapsedTime();
1844   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1845   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1846   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1847   _prev_collection_pause_end_ms += elapsed_time_ms;
1848 
1849   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1850 }
1851 
1852 // Add the heap region at the head of the non-incremental collection set
1853 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1854   assert(_inc_cset_build_state == Active, "Precondition");
1855   assert(hr->is_old(), "the region should be old");
1856 
1857   assert(!hr->in_collection_set(), "should not already be in the CSet");
1858   _g1->register_old_region_with_cset(hr);
1859   hr->set_next_in_collection_set(_collection_set);
1860   _collection_set = hr;
1861   _collection_set_bytes_used_before += hr->used();
1862   size_t rs_length = hr->rem_set()->occupied();
1863   _recorded_rs_lengths += rs_length;
1864   _old_cset_region_length += 1;
1865 }
1866 
1867 // Initialize the per-collection-set information
1868 void G1CollectorPolicy::start_incremental_cset_building() {
1869   assert(_inc_cset_build_state == Inactive, "Precondition");
1870 
1871   _inc_cset_head = NULL;
1872   _inc_cset_tail = NULL;
1873   _inc_cset_bytes_used_before = 0;
1874 
1875   _inc_cset_max_finger = 0;
1876   _inc_cset_recorded_rs_lengths = 0;
1877   _inc_cset_recorded_rs_lengths_diffs = 0;
1878   _inc_cset_predicted_elapsed_time_ms = 0.0;
1879   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1880   _inc_cset_build_state = Active;
1881 }
1882 
1883 void G1CollectorPolicy::finalize_incremental_cset_building() {
1884   assert(_inc_cset_build_state == Active, "Precondition");
1885   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1886 
1887   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1888   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1889   // that adds a new region to the CSet. Further updates by the
1890   // concurrent refinement thread that samples the young RSet lengths
1891   // are accumulated in the *_diffs fields. Here we add the diffs to
1892   // the "main" fields.
1893 
1894   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1895     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1896   } else {
1897     // This is defensive. The diff should in theory be always positive
1898     // as RSets can only grow between GCs. However, given that we
1899     // sample their size concurrently with other threads updating them
1900     // it's possible that we might get the wrong size back, which
1901     // could make the calculations somewhat inaccurate.
1902     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1903     if (_inc_cset_recorded_rs_lengths >= diffs) {
1904       _inc_cset_recorded_rs_lengths -= diffs;
1905     } else {
1906       _inc_cset_recorded_rs_lengths = 0;
1907     }
1908   }
1909   _inc_cset_predicted_elapsed_time_ms +=
1910                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1911 
1912   _inc_cset_recorded_rs_lengths_diffs = 0;
1913   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1914 }
1915 
1916 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1917   // This routine is used when:
1918   // * adding survivor regions to the incremental cset at the end of an
1919   //   evacuation pause,
1920   // * adding the current allocation region to the incremental cset
1921   //   when it is retired, and
1922   // * updating existing policy information for a region in the
1923   //   incremental cset via young list RSet sampling.
1924   // Therefore this routine may be called at a safepoint by the
1925   // VM thread, or in-between safepoints by mutator threads (when
1926   // retiring the current allocation region) or a concurrent
1927   // refine thread (RSet sampling).
1928 
1929   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1930   size_t used_bytes = hr->used();
1931   _inc_cset_recorded_rs_lengths += rs_length;
1932   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1933   _inc_cset_bytes_used_before += used_bytes;
1934 
1935   // Cache the values we have added to the aggregated information
1936   // in the heap region in case we have to remove this region from
1937   // the incremental collection set, or it is updated by the
1938   // rset sampling code
1939   hr->set_recorded_rs_length(rs_length);
1940   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1941 }
1942 
1943 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1944                                                      size_t new_rs_length) {
1945   // Update the CSet information that is dependent on the new RS length
1946   assert(hr->is_young(), "Precondition");
1947   assert(!SafepointSynchronize::is_at_safepoint(),
1948                                                "should not be at a safepoint");
1949 
1950   // We could have updated _inc_cset_recorded_rs_lengths and
1951   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1952   // that atomically, as this code is executed by a concurrent
1953   // refinement thread, potentially concurrently with a mutator thread
1954   // allocating a new region and also updating the same fields. To
1955   // avoid the atomic operations we accumulate these updates on two
1956   // separate fields (*_diffs) and we'll just add them to the "main"
1957   // fields at the start of a GC.
1958 
1959   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1960   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1961   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1962 
1963   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1964   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
1965   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1966   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1967 
1968   hr->set_recorded_rs_length(new_rs_length);
1969   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1970 }
1971 
1972 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1973   assert(hr->is_young(), "invariant");
1974   assert(hr->young_index_in_cset() > -1, "should have already been set");
1975   assert(_inc_cset_build_state == Active, "Precondition");
1976 
1977   // We need to clear and set the cached recorded/cached collection set
1978   // information in the heap region here (before the region gets added
1979   // to the collection set). An individual heap region's cached values
1980   // are calculated, aggregated with the policy collection set info,
1981   // and cached in the heap region here (initially) and (subsequently)
1982   // by the Young List sampling code.
1983 
1984   size_t rs_length = hr->rem_set()->occupied();
1985   add_to_incremental_cset_info(hr, rs_length);
1986 
1987   HeapWord* hr_end = hr->end();
1988   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1989 
1990   assert(!hr->in_collection_set(), "invariant");
1991   _g1->register_young_region_with_cset(hr);
1992   assert(hr->next_in_collection_set() == NULL, "invariant");
1993 }
1994 
1995 // Add the region at the RHS of the incremental cset
1996 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1997   // We should only ever be appending survivors at the end of a pause
1998   assert(hr->is_survivor(), "Logic");
1999 
2000   // Do the 'common' stuff
2001   add_region_to_incremental_cset_common(hr);
2002 
2003   // Now add the region at the right hand side
2004   if (_inc_cset_tail == NULL) {
2005     assert(_inc_cset_head == NULL, "invariant");
2006     _inc_cset_head = hr;
2007   } else {
2008     _inc_cset_tail->set_next_in_collection_set(hr);
2009   }
2010   _inc_cset_tail = hr;
2011 }
2012 
2013 // Add the region to the LHS of the incremental cset
2014 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
2015   // Survivors should be added to the RHS at the end of a pause
2016   assert(hr->is_eden(), "Logic");
2017 
2018   // Do the 'common' stuff
2019   add_region_to_incremental_cset_common(hr);
2020 
2021   // Add the region at the left hand side
2022   hr->set_next_in_collection_set(_inc_cset_head);
2023   if (_inc_cset_head == NULL) {
2024     assert(_inc_cset_tail == NULL, "Invariant");
2025     _inc_cset_tail = hr;
2026   }
2027   _inc_cset_head = hr;
2028 }
2029 
2030 #ifndef PRODUCT
2031 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
2032   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
2033 
2034   st->print_cr("\nCollection_set:");
2035   HeapRegion* csr = list_head;
2036   while (csr != NULL) {
2037     HeapRegion* next = csr->next_in_collection_set();
2038     assert(csr->in_collection_set(), "bad CS");
2039     st->print_cr("  " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
2040                  HR_FORMAT_PARAMS(csr),
2041                  p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
2042                  csr->age_in_surv_rate_group_cond());
2043     csr = next;
2044   }
2045 }
2046 #endif // !PRODUCT
2047 
2048 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
2049   // Returns the given amount of reclaimable bytes (that represents
2050   // the amount of reclaimable space still to be collected) as a
2051   // percentage of the current heap capacity.
2052   size_t capacity_bytes = _g1->capacity();
2053   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
2054 }
2055 
2056 void G1CollectorPolicy::maybe_start_marking() {
2057   if (need_to_start_conc_mark("end of GC")) {
2058     // Note: this might have already been set, if during the last
2059     // pause we decided to start a cycle but at the beginning of
2060     // this pause we decided to postpone it. That's OK.
2061     collector_state()->set_initiate_conc_mark_if_possible(true);
2062   }  
2063 }
2064 
2065 G1CollectorPolicy::PauseKind G1CollectorPolicy::young_gc_pause_kind() const {
2066   assert(!collector_state()->full_collection(), "must be");
2067   if (collector_state()->during_initial_mark_pause()) {
2068     assert(collector_state()->last_gc_was_young(), "must be");
2069     assert(!collector_state()->last_young_gc(), "must be");
2070     return InitialMarkGC;
2071   } else if (collector_state()->last_young_gc()) {
2072     assert(!collector_state()->during_initial_mark_pause(), "must be");
2073     assert(collector_state()->last_gc_was_young(), "must be");   
2074     return LastYoungGC;
2075   } else if (!collector_state()->last_gc_was_young()) {
2076     assert(!collector_state()->during_initial_mark_pause(), "must be");
2077     assert(!collector_state()->last_young_gc(), "must be");
2078     return MixedGC;
2079   } else {
2080     assert(collector_state()->last_gc_was_young(), "must be");
2081     assert(!collector_state()->during_initial_mark_pause(), "must be");
2082     assert(!collector_state()->last_young_gc(), "must be");
2083     return YoungOnlyGC;
2084   }
2085 }
2086 
2087 void G1CollectorPolicy::record_pause(PauseKind kind, double start, double end) {
2088   // Manage the MMU tracker. For some reason it ignores Full GCs.
2089   if (kind != FullGC) {
2090     _mmu_tracker->add_pause(start, end);
2091   }
2092   // Manage the mutator time tracking from initial mark to first mixed gc.
2093   switch (kind) {
2094     case FullGC:
2095       abort_time_to_mixed_tracking();
2096       break;
2097     case Cleanup:
2098     case Remark:
2099     case YoungOnlyGC:
2100     case LastYoungGC:
2101       _initial_mark_to_mixed.add_pause(end - start);
2102       break;
2103     case InitialMarkGC:
2104       _initial_mark_to_mixed.record_initial_mark_end(end);
2105       break;
2106     case MixedGC:
2107       _initial_mark_to_mixed.record_mixed_gc_start(start);
2108       break;
2109     default:
2110       ShouldNotReachHere();
2111   }
2112 }
2113 
2114 void G1CollectorPolicy::abort_time_to_mixed_tracking() {
2115   _initial_mark_to_mixed.reset();
2116 }
2117 
2118 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
2119                                                 const char* false_action_str) const {
2120   CollectionSetChooser* cset_chooser = _collectionSetChooser;
2121   if (cset_chooser->is_empty()) {
2122     ergo_verbose0(ErgoMixedGCs,
2123                   false_action_str,
2124                   ergo_format_reason("candidate old regions not available"));
2125     return false;
2126   }
2127 
2128   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
2129   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2130   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2131   double threshold = (double) G1HeapWastePercent;
2132   if (reclaimable_perc <= threshold) {
2133     ergo_verbose4(ErgoMixedGCs,
2134               false_action_str,
2135               ergo_format_reason("reclaimable percentage not over threshold")
2136               ergo_format_region("candidate old regions")
2137               ergo_format_byte_perc("reclaimable")
2138               ergo_format_perc("threshold"),
2139               cset_chooser->remaining_regions(),
2140               reclaimable_bytes,
2141               reclaimable_perc, threshold);
2142     return false;
2143   }
2144 
2145   ergo_verbose4(ErgoMixedGCs,
2146                 true_action_str,
2147                 ergo_format_reason("candidate old regions available")
2148                 ergo_format_region("candidate old regions")
2149                 ergo_format_byte_perc("reclaimable")
2150                 ergo_format_perc("threshold"),
2151                 cset_chooser->remaining_regions(),
2152                 reclaimable_bytes,
2153                 reclaimable_perc, threshold);
2154   return true;
2155 }
2156 
2157 uint G1CollectorPolicy::calc_min_old_cset_length() const {
2158   // The min old CSet region bound is based on the maximum desired
2159   // number of mixed GCs after a cycle. I.e., even if some old regions
2160   // look expensive, we should add them to the CSet anyway to make
2161   // sure we go through the available old regions in no more than the
2162   // maximum desired number of mixed GCs.
2163   //
2164   // The calculation is based on the number of marked regions we added
2165   // to the CSet chooser in the first place, not how many remain, so
2166   // that the result is the same during all mixed GCs that follow a cycle.
2167 
2168   const size_t region_num = (size_t) _collectionSetChooser->length();
2169   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
2170   size_t result = region_num / gc_num;
2171   // emulate ceiling
2172   if (result * gc_num < region_num) {
2173     result += 1;
2174   }
2175   return (uint) result;
2176 }
2177 
2178 uint G1CollectorPolicy::calc_max_old_cset_length() const {
2179   // The max old CSet region bound is based on the threshold expressed
2180   // as a percentage of the heap size. I.e., it should bound the
2181   // number of old regions added to the CSet irrespective of how many
2182   // of them are available.
2183 
2184   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
2185   const size_t region_num = g1h->num_regions();
2186   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
2187   size_t result = region_num * perc / 100;
2188   // emulate ceiling
2189   if (100 * result < region_num * perc) {
2190     result += 1;
2191   }
2192   return (uint) result;
2193 }
2194 
2195 
2196 double G1CollectorPolicy::finalize_young_cset_part(double target_pause_time_ms) {
2197   double young_start_time_sec = os::elapsedTime();
2198 
2199   YoungList* young_list = _g1->young_list();
2200   finalize_incremental_cset_building();
2201 
2202   guarantee(target_pause_time_ms > 0.0,
2203             "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
2204   guarantee(_collection_set == NULL, "Precondition");
2205 
2206   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
2207   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
2208 
2209   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2210                 "start choosing CSet",
2211                 ergo_format_size("_pending_cards")
2212                 ergo_format_ms("predicted base time")
2213                 ergo_format_ms("remaining time")
2214                 ergo_format_ms("target pause time"),
2215                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
2216 
2217   collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
2218 
2219   if (collector_state()->last_gc_was_young()) {
2220     _trace_young_gen_time_data.increment_young_collection_count();
2221   } else {
2222     _trace_young_gen_time_data.increment_mixed_collection_count();
2223   }
2224 
2225   // The young list is laid with the survivor regions from the previous
2226   // pause are appended to the RHS of the young list, i.e.
2227   //   [Newly Young Regions ++ Survivors from last pause].
2228 
2229   uint survivor_region_length = young_list->survivor_length();
2230   uint eden_region_length = young_list->eden_length();
2231   init_cset_region_lengths(eden_region_length, survivor_region_length);
2232 
2233   HeapRegion* hr = young_list->first_survivor_region();
2234   while (hr != NULL) {
2235     assert(hr->is_survivor(), "badly formed young list");
2236     // There is a convention that all the young regions in the CSet
2237     // are tagged as "eden", so we do this for the survivors here. We
2238     // use the special set_eden_pre_gc() as it doesn't check that the
2239     // region is free (which is not the case here).
2240     hr->set_eden_pre_gc();
2241     hr = hr->get_next_young_region();
2242   }
2243 
2244   // Clear the fields that point to the survivor list - they are all young now.
2245   young_list->clear_survivors();
2246 
2247   _collection_set = _inc_cset_head;
2248   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
2249   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
2250 
2251   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
2252                 "add young regions to CSet",
2253                 ergo_format_region("eden")
2254                 ergo_format_region("survivors")
2255                 ergo_format_ms("predicted young region time")
2256                 ergo_format_ms("target pause time"),
2257                 eden_region_length, survivor_region_length,
2258                 _inc_cset_predicted_elapsed_time_ms,
2259                 target_pause_time_ms);
2260 
2261   // The number of recorded young regions is the incremental
2262   // collection set's current size
2263   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
2264 
2265   double young_end_time_sec = os::elapsedTime();
2266   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
2267 
2268   return time_remaining_ms;
2269 }
2270 
2271 void G1CollectorPolicy::finalize_old_cset_part(double time_remaining_ms) {
2272   double non_young_start_time_sec = os::elapsedTime();
2273   double predicted_old_time_ms = 0.0;
2274 
2275 
2276   if (!collector_state()->gcs_are_young()) {
2277     CollectionSetChooser* cset_chooser = _collectionSetChooser;
2278     cset_chooser->verify();
2279     const uint min_old_cset_length = calc_min_old_cset_length();
2280     const uint max_old_cset_length = calc_max_old_cset_length();
2281 
2282     uint expensive_region_num = 0;
2283     bool check_time_remaining = adaptive_young_list_length();
2284 
2285     HeapRegion* hr = cset_chooser->peek();
2286     while (hr != NULL) {
2287       if (old_cset_region_length() >= max_old_cset_length) {
2288         // Added maximum number of old regions to the CSet.
2289         ergo_verbose2(ErgoCSetConstruction,
2290                       "finish adding old regions to CSet",
2291                       ergo_format_reason("old CSet region num reached max")
2292                       ergo_format_region("old")
2293                       ergo_format_region("max"),
2294                       old_cset_region_length(), max_old_cset_length);
2295         break;
2296       }
2297 
2298 
2299       // Stop adding regions if the remaining reclaimable space is
2300       // not above G1HeapWastePercent.
2301       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
2302       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
2303       double threshold = (double) G1HeapWastePercent;
2304       if (reclaimable_perc <= threshold) {
2305         // We've added enough old regions that the amount of uncollected
2306         // reclaimable space is at or below the waste threshold. Stop
2307         // adding old regions to the CSet.
2308         ergo_verbose5(ErgoCSetConstruction,
2309                       "finish adding old regions to CSet",
2310                       ergo_format_reason("reclaimable percentage not over threshold")
2311                       ergo_format_region("old")
2312                       ergo_format_region("max")
2313                       ergo_format_byte_perc("reclaimable")
2314                       ergo_format_perc("threshold"),
2315                       old_cset_region_length(),
2316                       max_old_cset_length,
2317                       reclaimable_bytes,
2318                       reclaimable_perc, threshold);
2319         break;
2320       }
2321 
2322       double predicted_time_ms = predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
2323       if (check_time_remaining) {
2324         if (predicted_time_ms > time_remaining_ms) {
2325           // Too expensive for the current CSet.
2326 
2327           if (old_cset_region_length() >= min_old_cset_length) {
2328             // We have added the minimum number of old regions to the CSet,
2329             // we are done with this CSet.
2330             ergo_verbose4(ErgoCSetConstruction,
2331                           "finish adding old regions to CSet",
2332                           ergo_format_reason("predicted time is too high")
2333                           ergo_format_ms("predicted time")
2334                           ergo_format_ms("remaining time")
2335                           ergo_format_region("old")
2336                           ergo_format_region("min"),
2337                           predicted_time_ms, time_remaining_ms,
2338                           old_cset_region_length(), min_old_cset_length);
2339             break;
2340           }
2341 
2342           // We'll add it anyway given that we haven't reached the
2343           // minimum number of old regions.
2344           expensive_region_num += 1;
2345         }
2346       } else {
2347         if (old_cset_region_length() >= min_old_cset_length) {
2348           // In the non-auto-tuning case, we'll finish adding regions
2349           // to the CSet if we reach the minimum.
2350           ergo_verbose2(ErgoCSetConstruction,
2351                         "finish adding old regions to CSet",
2352                         ergo_format_reason("old CSet region num reached min")
2353                         ergo_format_region("old")
2354                         ergo_format_region("min"),
2355                         old_cset_region_length(), min_old_cset_length);
2356           break;
2357         }
2358       }
2359 
2360       // We will add this region to the CSet.
2361       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
2362       predicted_old_time_ms += predicted_time_ms;
2363       cset_chooser->pop(); // already have region via peek()
2364       _g1->old_set_remove(hr);
2365       add_old_region_to_cset(hr);
2366 
2367       hr = cset_chooser->peek();
2368     }
2369     if (hr == NULL) {
2370       ergo_verbose0(ErgoCSetConstruction,
2371                     "finish adding old regions to CSet",
2372                     ergo_format_reason("candidate old regions not available"));
2373     }
2374 
2375     if (expensive_region_num > 0) {
2376       // We print the information once here at the end, predicated on
2377       // whether we added any apparently expensive regions or not, to
2378       // avoid generating output per region.
2379       ergo_verbose4(ErgoCSetConstruction,
2380                     "added expensive regions to CSet",
2381                     ergo_format_reason("old CSet region num not reached min")
2382                     ergo_format_region("old")
2383                     ergo_format_region("expensive")
2384                     ergo_format_region("min")
2385                     ergo_format_ms("remaining time"),
2386                     old_cset_region_length(),
2387                     expensive_region_num,
2388                     min_old_cset_length,
2389                     time_remaining_ms);
2390     }
2391 
2392     cset_chooser->verify();
2393   }
2394 
2395   stop_incremental_cset_building();
2396 
2397   ergo_verbose3(ErgoCSetConstruction,
2398                 "finish choosing CSet",
2399                 ergo_format_region("old")
2400                 ergo_format_ms("predicted old region time")
2401                 ergo_format_ms("time remaining"),
2402                 old_cset_region_length(),
2403                 predicted_old_time_ms, time_remaining_ms);
2404 
2405   double non_young_end_time_sec = os::elapsedTime();
2406   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2407 }
2408 
2409 void TraceYoungGenTimeData::record_start_collection(double time_to_stop_the_world_ms) {
2410   if(TraceYoungGenTime) {
2411     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2412   }
2413 }
2414 
2415 void TraceYoungGenTimeData::record_yield_time(double yield_time_ms) {
2416   if(TraceYoungGenTime) {
2417     _all_yield_times_ms.add(yield_time_ms);
2418   }
2419 }
2420 
2421 void TraceYoungGenTimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2422   if(TraceYoungGenTime) {
2423     _total.add(pause_time_ms);
2424     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2425     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2426     _parallel.add(phase_times->cur_collection_par_time_ms());
2427     _ext_root_scan.add(phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan));
2428     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
2429     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
2430     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
2431     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
2432     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
2433 
2434     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
2435       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
2436       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
2437       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
2438       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
2439       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
2440 
2441     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2442     _parallel_other.add(parallel_other_time);
2443     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2444   }
2445 }
2446 
2447 void TraceYoungGenTimeData::increment_young_collection_count() {
2448   if(TraceYoungGenTime) {
2449     ++_young_pause_num;
2450   }
2451 }
2452 
2453 void TraceYoungGenTimeData::increment_mixed_collection_count() {
2454   if(TraceYoungGenTime) {
2455     ++_mixed_pause_num;
2456   }
2457 }
2458 
2459 void TraceYoungGenTimeData::print_summary(const char* str,
2460                                           const NumberSeq* seq) const {
2461   double sum = seq->sum();
2462   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2463                 str, sum / 1000.0, seq->avg());
2464 }
2465 
2466 void TraceYoungGenTimeData::print_summary_sd(const char* str,
2467                                              const NumberSeq* seq) const {
2468   print_summary(str, seq);
2469   gclog_or_tty->print_cr("%45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2470                 "(num", seq->num(), seq->sd(), seq->maximum());
2471 }
2472 
2473 void TraceYoungGenTimeData::print() const {
2474   if (!TraceYoungGenTime) {
2475     return;
2476   }
2477 
2478   gclog_or_tty->print_cr("ALL PAUSES");
2479   print_summary_sd("   Total", &_total);
2480   gclog_or_tty->cr();
2481   gclog_or_tty->cr();
2482   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2483   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2484   gclog_or_tty->cr();
2485 
2486   gclog_or_tty->print_cr("EVACUATION PAUSES");
2487 
2488   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2489     gclog_or_tty->print_cr("none");
2490   } else {
2491     print_summary_sd("   Evacuation Pauses", &_total);
2492     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2493     print_summary("      Parallel Time", &_parallel);
2494     print_summary("         Ext Root Scanning", &_ext_root_scan);
2495     print_summary("         SATB Filtering", &_satb_filtering);
2496     print_summary("         Update RS", &_update_rs);
2497     print_summary("         Scan RS", &_scan_rs);
2498     print_summary("         Object Copy", &_obj_copy);
2499     print_summary("         Termination", &_termination);
2500     print_summary("         Parallel Other", &_parallel_other);
2501     print_summary("      Clear CT", &_clear_ct);
2502     print_summary("      Other", &_other);
2503   }
2504   gclog_or_tty->cr();
2505 
2506   gclog_or_tty->print_cr("MISC");
2507   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2508   print_summary_sd("   Yields", &_all_yield_times_ms);
2509 }
2510 
2511 void TraceOldGenTimeData::record_full_collection(double full_gc_time_ms) {
2512   if (TraceOldGenTime) {
2513     _all_full_gc_times.add(full_gc_time_ms);
2514   }
2515 }
2516 
2517 void TraceOldGenTimeData::print() const {
2518   if (!TraceOldGenTime) {
2519     return;
2520   }
2521 
2522   if (_all_full_gc_times.num() > 0) {
2523     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2524       _all_full_gc_times.num(),
2525       _all_full_gc_times.sum() / 1000.0);
2526     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2527     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2528       _all_full_gc_times.sd(),
2529       _all_full_gc_times.maximum());
2530   }
2531 }
--- EOF ---