1 /*
   2  * Copyright (c) 2001, 2012, 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_implementation/g1/concurrentG1Refine.hpp"
  27 #include "gc_implementation/g1/concurrentMark.hpp"
  28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  33 #include "gc_implementation/g1/g1Log.hpp"
  34 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  35 #include "gc_implementation/shared/gcPolicyCounters.hpp"
  36 #include "runtime/arguments.hpp"
  37 #include "runtime/java.hpp"
  38 #include "runtime/mutexLocker.hpp"
  39 #include "utilities/debug.hpp"
  40 
  41 // Different defaults for different number of GC threads
  42 // They were chosen by running GCOld and SPECjbb on debris with different
  43 //   numbers of GC threads and choosing them based on the results
  44 
  45 // all the same
  46 static double rs_length_diff_defaults[] = {
  47   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
  48 };
  49 
  50 static double cost_per_card_ms_defaults[] = {
  51   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
  52 };
  53 
  54 // all the same
  55 static double young_cards_per_entry_ratio_defaults[] = {
  56   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
  57 };
  58 
  59 static double cost_per_entry_ms_defaults[] = {
  60   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
  61 };
  62 
  63 static double cost_per_byte_ms_defaults[] = {
  64   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
  65 };
  66 
  67 // these should be pretty consistent
  68 static double constant_other_time_ms_defaults[] = {
  69   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
  70 };
  71 
  72 
  73 static double young_other_cost_per_region_ms_defaults[] = {
  74   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
  75 };
  76 
  77 static double non_young_other_cost_per_region_ms_defaults[] = {
  78   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
  79 };
  80 
  81 G1CollectorPolicy::G1CollectorPolicy() :
  82   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
  83                         ? ParallelGCThreads : 1),
  84 
  85   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  86   _stop_world_start(0.0),
  87 
  88   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  89   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  90 
  91   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  92   _prev_collection_pause_end_ms(0.0),
  93   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  94   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 104   _non_young_other_cost_per_region_ms_seq(
 105                                          new TruncatedSeq(TruncatedSeqLength)),
 106 
 107   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 108   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 109 
 110   _pause_time_target_ms((double) MaxGCPauseMillis),
 111 
 112   _gcs_are_young(true),
 113 
 114   _during_marking(false),
 115   _in_marking_window(false),
 116   _in_marking_window_im(false),
 117 
 118   _recent_prev_end_times_for_all_gcs_sec(
 119                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 120 
 121   _recent_avg_pause_time_ratio(0.0),
 122 
 123   _initiate_conc_mark_if_possible(false),
 124   _during_initial_mark_pause(false),
 125   _last_young_gc(false),
 126   _last_gc_was_young(false),
 127 
 128   _eden_bytes_before_gc(0),
 129   _survivor_bytes_before_gc(0),
 130   _capacity_before_gc(0),
 131 
 132   _eden_cset_region_length(0),
 133   _survivor_cset_region_length(0),
 134   _old_cset_region_length(0),
 135 
 136   _collection_set(NULL),
 137   _collection_set_bytes_used_before(0),
 138 
 139   // Incremental CSet attributes
 140   _inc_cset_build_state(Inactive),
 141   _inc_cset_head(NULL),
 142   _inc_cset_tail(NULL),
 143   _inc_cset_bytes_used_before(0),
 144   _inc_cset_max_finger(NULL),
 145   _inc_cset_recorded_rs_lengths(0),
 146   _inc_cset_recorded_rs_lengths_diffs(0),
 147   _inc_cset_predicted_elapsed_time_ms(0.0),
 148   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 149 
 150 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 151 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 152 #endif // _MSC_VER
 153 
 154   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
 155                                                  G1YoungSurvRateNumRegionsSummary)),
 156   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
 157                                               G1YoungSurvRateNumRegionsSummary)),
 158   // add here any more surv rate groups
 159   _recorded_survivor_regions(0),
 160   _recorded_survivor_head(NULL),
 161   _recorded_survivor_tail(NULL),
 162   _survivors_age_table(true),
 163 
 164   _gc_overhead_perc(0.0) {
 165 
 166   // Set up the region size and associated fields. Given that the
 167   // policy is created before the heap, we have to set this up here,
 168   // so it's done as soon as possible.
 169   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
 170   HeapRegionRemSet::setup_remset_size();
 171 
 172   G1ErgoVerbose::initialize();
 173   if (PrintAdaptiveSizePolicy) {
 174     // Currently, we only use a single switch for all the heuristics.
 175     G1ErgoVerbose::set_enabled(true);
 176     // Given that we don't currently have a verboseness level
 177     // parameter, we'll hardcode this to high. This can be easily
 178     // changed in the future.
 179     G1ErgoVerbose::set_level(ErgoHigh);
 180   } else {
 181     G1ErgoVerbose::set_enabled(false);
 182   }
 183 
 184   // Verify PLAB sizes
 185   const size_t region_size = HeapRegion::GrainWords;
 186   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
 187     char buffer[128];
 188     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
 189                  OldPLABSize > region_size ? "Old" : "Young", region_size);
 190     vm_exit_during_initialization(buffer);
 191   }
 192 
 193   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 194   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 195 
 196   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 197 
 198   int index = MIN2(_parallel_gc_threads - 1, 7);
 199 
 200   _pending_card_diff_seq->add(0.0);
 201   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 202   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 203   _young_cards_per_entry_ratio_seq->add(
 204                                   young_cards_per_entry_ratio_defaults[index]);
 205   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 206   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 207   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 208   _young_other_cost_per_region_ms_seq->add(
 209                                young_other_cost_per_region_ms_defaults[index]);
 210   _non_young_other_cost_per_region_ms_seq->add(
 211                            non_young_other_cost_per_region_ms_defaults[index]);
 212 
 213   // Below, we might need to calculate the pause time target based on
 214   // the pause interval. When we do so we are going to give G1 maximum
 215   // flexibility and allow it to do pauses when it needs to. So, we'll
 216   // arrange that the pause interval to be pause time target + 1 to
 217   // ensure that a) the pause time target is maximized with respect to
 218   // the pause interval and b) we maintain the invariant that pause
 219   // time target < pause interval. If the user does not want this
 220   // maximum flexibility, they will have to set the pause interval
 221   // explicitly.
 222 
 223   // First make sure that, if either parameter is set, its value is
 224   // reasonable.
 225   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 226     if (MaxGCPauseMillis < 1) {
 227       vm_exit_during_initialization("MaxGCPauseMillis should be "
 228                                     "greater than 0");
 229     }
 230   }
 231   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 232     if (GCPauseIntervalMillis < 1) {
 233       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 234                                     "greater than 0");
 235     }
 236   }
 237 
 238   // Then, if the pause time target parameter was not set, set it to
 239   // the default value.
 240   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 241     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 242       // The default pause time target in G1 is 200ms
 243       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 244     } else {
 245       // We do not allow the pause interval to be set without the
 246       // pause time target
 247       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 248                                     "without setting MaxGCPauseMillis");
 249     }
 250   }
 251 
 252   // Then, if the interval parameter was not set, set it according to
 253   // the pause time target (this will also deal with the case when the
 254   // pause time target is the default value).
 255   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 256     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 257   }
 258 
 259   // Finally, make sure that the two parameters are consistent.
 260   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 261     char buffer[256];
 262     jio_snprintf(buffer, 256,
 263                  "MaxGCPauseMillis (%u) should be less than "
 264                  "GCPauseIntervalMillis (%u)",
 265                  MaxGCPauseMillis, GCPauseIntervalMillis);
 266     vm_exit_during_initialization(buffer);
 267   }
 268 
 269   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 270   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 271   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 272   _sigma = (double) G1ConfidencePercent / 100.0;
 273 
 274   // start conservatively (around 50ms is about right)
 275   _concurrent_mark_remark_times_ms->add(0.05);
 276   _concurrent_mark_cleanup_times_ms->add(0.20);
 277   _tenuring_threshold = MaxTenuringThreshold;
 278   // _max_survivor_regions will be calculated by
 279   // update_young_list_target_length() during initialization.
 280   _max_survivor_regions = 0;
 281 
 282   assert(GCTimeRatio > 0,
 283          "we should have set it to a default value set_g1_gc_flags() "
 284          "if a user set it to 0");
 285   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 286 
 287   uintx reserve_perc = G1ReservePercent;
 288   // Put an artificial ceiling on this so that it's not set to a silly value.
 289   if (reserve_perc > 50) {
 290     reserve_perc = 50;
 291     warning("G1ReservePercent is set to a value that is too large, "
 292             "it's been updated to %u", reserve_perc);
 293   }
 294   _reserve_factor = (double) reserve_perc / 100.0;
 295   // This will be set when the heap is expanded
 296   // for the first time during initialization.
 297   _reserve_regions = 0;
 298 
 299   initialize_all();
 300   _collectionSetChooser = new CollectionSetChooser();
 301   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 302 }
 303 
 304 void G1CollectorPolicy::initialize_flags() {
 305   set_min_alignment(HeapRegion::GrainBytes);
 306   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
 307   if (SurvivorRatio < 1) {
 308     vm_exit_during_initialization("Invalid survivor ratio specified");
 309   }
 310   CollectorPolicy::initialize_flags();
 311 }
 312 
 313 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
 314   assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");
 315   assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");
 316   assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");
 317 
 318   if (FLAG_IS_CMDLINE(NewRatio)) {
 319     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 320       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 321     } else {
 322       _sizer_kind = SizerNewRatio;
 323       _adaptive_size = false;
 324       return;
 325     }
 326   }
 327 
 328   if (FLAG_IS_CMDLINE(NewSize)) {
 329     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 330                                      1U);
 331     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 332       _max_desired_young_length =
 333                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 334                                   1U);
 335       _sizer_kind = SizerMaxAndNewSize;
 336       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 337     } else {
 338       _sizer_kind = SizerNewSizeOnly;
 339     }
 340   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 341     _max_desired_young_length =
 342                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 343                                   1U);
 344     _sizer_kind = SizerMaxNewSizeOnly;
 345   }
 346 }
 347 
 348 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 349   uint default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;
 350   return MAX2(1U, default_value);
 351 }
 352 
 353 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 354   uint default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;
 355   return MAX2(1U, default_value);
 356 }
 357 
 358 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 359   assert(new_number_of_heap_regions > 0, "Heap must be initialized");
 360 
 361   switch (_sizer_kind) {
 362     case SizerDefaults:
 363       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
 364       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
 365       break;
 366     case SizerNewSizeOnly:
 367       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
 368       _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
 369       break;
 370     case SizerMaxNewSizeOnly:
 371       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
 372       _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
 373       break;
 374     case SizerMaxAndNewSize:
 375       // Do nothing. Values set on the command line, don't update them at runtime.
 376       break;
 377     case SizerNewRatio:
 378       _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
 379       _max_desired_young_length = _min_desired_young_length;
 380       break;
 381     default:
 382       ShouldNotReachHere();
 383   }
 384 
 385   assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
 386 }
 387 
 388 void G1CollectorPolicy::init() {
 389   // Set aside an initial future to_space.
 390   _g1 = G1CollectedHeap::heap();
 391 
 392   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 393 
 394   initialize_gc_policy_counters();
 395 
 396   if (adaptive_young_list_length()) {
 397     _young_list_fixed_length = 0;
 398   } else {
 399     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 400   }
 401   _free_regions_at_end_of_collection = _g1->free_regions();
 402   update_young_list_target_length();
 403   _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
 404 
 405   // We may immediately start allocating regions and placing them on the
 406   // collection set list. Initialize the per-collection set info
 407   start_incremental_cset_building();
 408 }
 409 
 410 // Create the jstat counters for the policy.
 411 void G1CollectorPolicy::initialize_gc_policy_counters() {
 412   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 413 }
 414 
 415 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 416                                          double base_time_ms,
 417                                          uint base_free_regions,
 418                                          double target_pause_time_ms) {
 419   if (young_length >= base_free_regions) {
 420     // end condition 1: not enough space for the young regions
 421     return false;
 422   }
 423 
 424   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 425   size_t bytes_to_copy =
 426                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 427   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 428   double young_other_time_ms = predict_young_other_time_ms(young_length);
 429   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 430   if (pause_time_ms > target_pause_time_ms) {
 431     // end condition 2: prediction is over the target pause time
 432     return false;
 433   }
 434 
 435   size_t free_bytes =
 436                    (base_free_regions - young_length) * HeapRegion::GrainBytes;
 437   if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
 438     // end condition 3: out-of-space (conservatively!)
 439     return false;
 440   }
 441 
 442   // success!
 443   return true;
 444 }
 445 
 446 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 447   // re-calculate the necessary reserve
 448   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 449   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 450   // smaller than 1.0) we'll get 1.
 451   _reserve_regions = (uint) ceil(reserve_regions_d);
 452 
 453   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 454 }
 455 
 456 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 457                                                        uint base_min_length) {
 458   uint desired_min_length = 0;
 459   if (adaptive_young_list_length()) {
 460     if (_alloc_rate_ms_seq->num() > 3) {
 461       double now_sec = os::elapsedTime();
 462       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 463       double alloc_rate_ms = predict_alloc_rate_ms();
 464       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 465     } else {
 466       // otherwise we don't have enough info to make the prediction
 467     }
 468   }
 469   desired_min_length += base_min_length;
 470   // make sure we don't go below any user-defined minimum bound
 471   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 472 }
 473 
 474 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
 475   // Here, we might want to also take into account any additional
 476   // constraints (i.e., user-defined minimum bound). Currently, we
 477   // effectively don't set this bound.
 478   return _young_gen_sizer->max_desired_young_length();
 479 }
 480 
 481 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 482   if (rs_lengths == (size_t) -1) {
 483     // if it's set to the default value (-1), we should predict it;
 484     // otherwise, use the given value.
 485     rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
 486   }
 487 
 488   // Calculate the absolute and desired min bounds.
 489 
 490   // This is how many young regions we already have (currently: the survivors).
 491   uint base_min_length = recorded_survivor_regions();
 492   // This is the absolute minimum young length, which ensures that we
 493   // can allocate one eden region in the worst-case.
 494   uint absolute_min_length = base_min_length + 1;
 495   uint desired_min_length =
 496                      calculate_young_list_desired_min_length(base_min_length);
 497   if (desired_min_length < absolute_min_length) {
 498     desired_min_length = absolute_min_length;
 499   }
 500 
 501   // Calculate the absolute and desired max bounds.
 502 
 503   // We will try our best not to "eat" into the reserve.
 504   uint absolute_max_length = 0;
 505   if (_free_regions_at_end_of_collection > _reserve_regions) {
 506     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 507   }
 508   uint desired_max_length = calculate_young_list_desired_max_length();
 509   if (desired_max_length > absolute_max_length) {
 510     desired_max_length = absolute_max_length;
 511   }
 512 
 513   uint young_list_target_length = 0;
 514   if (adaptive_young_list_length()) {
 515     if (gcs_are_young()) {
 516       young_list_target_length =
 517                         calculate_young_list_target_length(rs_lengths,
 518                                                            base_min_length,
 519                                                            desired_min_length,
 520                                                            desired_max_length);
 521       _rs_lengths_prediction = rs_lengths;
 522     } else {
 523       // Don't calculate anything and let the code below bound it to
 524       // the desired_min_length, i.e., do the next GC as soon as
 525       // possible to maximize how many old regions we can add to it.
 526     }
 527   } else {
 528     // The user asked for a fixed young gen so we'll fix the young gen
 529     // whether the next GC is young or mixed.
 530     young_list_target_length = _young_list_fixed_length;
 531   }
 532 
 533   // Make sure we don't go over the desired max length, nor under the
 534   // desired min length. In case they clash, desired_min_length wins
 535   // which is why that test is second.
 536   if (young_list_target_length > desired_max_length) {
 537     young_list_target_length = desired_max_length;
 538   }
 539   if (young_list_target_length < desired_min_length) {
 540     young_list_target_length = desired_min_length;
 541   }
 542 
 543   assert(young_list_target_length > recorded_survivor_regions(),
 544          "we should be able to allocate at least one eden region");
 545   assert(young_list_target_length >= absolute_min_length, "post-condition");
 546   _young_list_target_length = young_list_target_length;
 547 
 548   update_max_gc_locker_expansion();
 549 }
 550 
 551 uint
 552 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 553                                                      uint base_min_length,
 554                                                      uint desired_min_length,
 555                                                      uint desired_max_length) {
 556   assert(adaptive_young_list_length(), "pre-condition");
 557   assert(gcs_are_young(), "only call this for young GCs");
 558 
 559   // In case some edge-condition makes the desired max length too small...
 560   if (desired_max_length <= desired_min_length) {
 561     return desired_min_length;
 562   }
 563 
 564   // We'll adjust min_young_length and max_young_length not to include
 565   // the already allocated young regions (i.e., so they reflect the
 566   // min and max eden regions we'll allocate). The base_min_length
 567   // will be reflected in the predictions by the
 568   // survivor_regions_evac_time prediction.
 569   assert(desired_min_length > base_min_length, "invariant");
 570   uint min_young_length = desired_min_length - base_min_length;
 571   assert(desired_max_length > base_min_length, "invariant");
 572   uint max_young_length = desired_max_length - base_min_length;
 573 
 574   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 575   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 576   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 577   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 578   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 579   double base_time_ms =
 580     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 581     survivor_regions_evac_time;
 582   uint available_free_regions = _free_regions_at_end_of_collection;
 583   uint base_free_regions = 0;
 584   if (available_free_regions > _reserve_regions) {
 585     base_free_regions = available_free_regions - _reserve_regions;
 586   }
 587 
 588   // Here, we will make sure that the shortest young length that
 589   // makes sense fits within the target pause time.
 590 
 591   if (predict_will_fit(min_young_length, base_time_ms,
 592                        base_free_regions, target_pause_time_ms)) {
 593     // The shortest young length will fit into the target pause time;
 594     // we'll now check whether the absolute maximum number of young
 595     // regions will fit in the target pause time. If not, we'll do
 596     // a binary search between min_young_length and max_young_length.
 597     if (predict_will_fit(max_young_length, base_time_ms,
 598                          base_free_regions, target_pause_time_ms)) {
 599       // The maximum young length will fit into the target pause time.
 600       // We are done so set min young length to the maximum length (as
 601       // the result is assumed to be returned in min_young_length).
 602       min_young_length = max_young_length;
 603     } else {
 604       // The maximum possible number of young regions will not fit within
 605       // the target pause time so we'll search for the optimal
 606       // length. The loop invariants are:
 607       //
 608       // min_young_length < max_young_length
 609       // min_young_length is known to fit into the target pause time
 610       // max_young_length is known not to fit into the target pause time
 611       //
 612       // Going into the loop we know the above hold as we've just
 613       // checked them. Every time around the loop we check whether
 614       // the middle value between min_young_length and
 615       // max_young_length fits into the target pause time. If it
 616       // does, it becomes the new min. If it doesn't, it becomes
 617       // the new max. This way we maintain the loop invariants.
 618 
 619       assert(min_young_length < max_young_length, "invariant");
 620       uint diff = (max_young_length - min_young_length) / 2;
 621       while (diff > 0) {
 622         uint young_length = min_young_length + diff;
 623         if (predict_will_fit(young_length, base_time_ms,
 624                              base_free_regions, target_pause_time_ms)) {
 625           min_young_length = young_length;
 626         } else {
 627           max_young_length = young_length;
 628         }
 629         assert(min_young_length <  max_young_length, "invariant");
 630         diff = (max_young_length - min_young_length) / 2;
 631       }
 632       // The results is min_young_length which, according to the
 633       // loop invariants, should fit within the target pause time.
 634 
 635       // These are the post-conditions of the binary search above:
 636       assert(min_young_length < max_young_length,
 637              "otherwise we should have discovered that max_young_length "
 638              "fits into the pause target and not done the binary search");
 639       assert(predict_will_fit(min_young_length, base_time_ms,
 640                               base_free_regions, target_pause_time_ms),
 641              "min_young_length, the result of the binary search, should "
 642              "fit into the pause target");
 643       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 644                                base_free_regions, target_pause_time_ms),
 645              "min_young_length, the result of the binary search, should be "
 646              "optimal, so no larger length should fit into the pause target");
 647     }
 648   } else {
 649     // Even the minimum length doesn't fit into the pause time
 650     // target, return it as the result nevertheless.
 651   }
 652   return base_min_length + min_young_length;
 653 }
 654 
 655 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
 656   double survivor_regions_evac_time = 0.0;
 657   for (HeapRegion * r = _recorded_survivor_head;
 658        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 659        r = r->get_next_young_region()) {
 660     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
 661   }
 662   return survivor_regions_evac_time;
 663 }
 664 
 665 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 666   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 667 
 668   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 669   if (rs_lengths > _rs_lengths_prediction) {
 670     // add 10% to avoid having to recalculate often
 671     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 672     update_young_list_target_length(rs_lengths_prediction);
 673   }
 674 }
 675 
 676 
 677 
 678 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 679                                                bool is_tlab,
 680                                                bool* gc_overhead_limit_was_exceeded) {
 681   guarantee(false, "Not using this policy feature yet.");
 682   return NULL;
 683 }
 684 
 685 // This method controls how a collector handles one or more
 686 // of its generations being fully allocated.
 687 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 688                                                        bool is_tlab) {
 689   guarantee(false, "Not using this policy feature yet.");
 690   return NULL;
 691 }
 692 
 693 
 694 #ifndef PRODUCT
 695 bool G1CollectorPolicy::verify_young_ages() {
 696   HeapRegion* head = _g1->young_list()->first_region();
 697   return
 698     verify_young_ages(head, _short_lived_surv_rate_group);
 699   // also call verify_young_ages on any additional surv rate groups
 700 }
 701 
 702 bool
 703 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 704                                      SurvRateGroup *surv_rate_group) {
 705   guarantee( surv_rate_group != NULL, "pre-condition" );
 706 
 707   const char* name = surv_rate_group->name();
 708   bool ret = true;
 709   int prev_age = -1;
 710 
 711   for (HeapRegion* curr = head;
 712        curr != NULL;
 713        curr = curr->get_next_young_region()) {
 714     SurvRateGroup* group = curr->surv_rate_group();
 715     if (group == NULL && !curr->is_survivor()) {
 716       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
 717       ret = false;
 718     }
 719 
 720     if (surv_rate_group == group) {
 721       int age = curr->age_in_surv_rate_group();
 722 
 723       if (age < 0) {
 724         gclog_or_tty->print_cr("## %s: encountered negative age", name);
 725         ret = false;
 726       }
 727 
 728       if (age <= prev_age) {
 729         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
 730                                "(%d, %d)", name, age, prev_age);
 731         ret = false;
 732       }
 733       prev_age = age;
 734     }
 735   }
 736 
 737   return ret;
 738 }
 739 #endif // PRODUCT
 740 
 741 void G1CollectorPolicy::record_full_collection_start() {
 742   _full_collection_start_sec = os::elapsedTime();
 743   // Release the future to-space so that it is available for compaction into.
 744   _g1->set_full_collection();
 745 }
 746 
 747 void G1CollectorPolicy::record_full_collection_end() {
 748   // Consider this like a collection pause for the purposes of allocation
 749   // since last pause.
 750   double end_sec = os::elapsedTime();
 751   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 752   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 753 
 754   _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
 755 
 756   update_recent_gc_times(end_sec, full_gc_time_ms);
 757 
 758   _g1->clear_full_collection();
 759 
 760   // "Nuke" the heuristics that control the young/mixed GC
 761   // transitions and make sure we start with young GCs after the Full GC.
 762   set_gcs_are_young(true);
 763   _last_young_gc = false;
 764   clear_initiate_conc_mark_if_possible();
 765   clear_during_initial_mark_pause();
 766   _in_marking_window = false;
 767   _in_marking_window_im = false;
 768 
 769   _short_lived_surv_rate_group->start_adding_regions();
 770   // also call this on any additional surv rate groups
 771 
 772   record_survivor_regions(0, NULL, NULL);
 773 
 774   _free_regions_at_end_of_collection = _g1->free_regions();
 775   // Reset survivors SurvRateGroup.
 776   _survivor_surv_rate_group->reset();
 777   update_young_list_target_length();
 778   _collectionSetChooser->clear();
 779 }
 780 
 781 void G1CollectorPolicy::record_stop_world_start() {
 782   _stop_world_start = os::elapsedTime();
 783 }
 784 
 785 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
 786                                                       size_t start_used) {
 787   // We only need to do this here as the policy will only be applied
 788   // to the GC we're about to start. so, no point is calculating this
 789   // every time we calculate / recalculate the target young length.
 790   update_survivors_policy();
 791 
 792   assert(_g1->used() == _g1->recalculate_used(),
 793          err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
 794                  _g1->used(), _g1->recalculate_used()));
 795 
 796   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 797   _trace_gen0_time_data.record_start_collection(s_w_t_ms);
 798   _stop_world_start = 0.0;
 799 
 800   phase_times()->_cur_collection_start_sec = start_time_sec;
 801   _cur_collection_pause_used_at_start_bytes = start_used;
 802   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
 803   _pending_cards = _g1->pending_card_num();
 804   _max_pending_cards = _g1->max_pending_card_num();
 805 
 806   _bytes_in_collection_set_before_gc = 0;
 807   _bytes_copied_during_gc = 0;
 808 
 809   YoungList* young_list = _g1->young_list();
 810   _eden_bytes_before_gc = young_list->eden_used_bytes();
 811   _survivor_bytes_before_gc = young_list->survivor_used_bytes();
 812   _capacity_before_gc = _g1->capacity();
 813 
 814   _last_gc_was_young = false;
 815 
 816   // do that for any other surv rate groups
 817   _short_lived_surv_rate_group->stop_adding_regions();
 818   _survivors_age_table.clear();
 819 
 820   assert( verify_young_ages(), "region age verification" );
 821 }
 822 
 823 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 824                                                    mark_init_elapsed_time_ms) {
 825   _during_marking = true;
 826   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
 827   clear_during_initial_mark_pause();
 828   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 829 }
 830 
 831 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 832   _mark_remark_start_sec = os::elapsedTime();
 833   _during_marking = false;
 834 }
 835 
 836 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 837   double end_time_sec = os::elapsedTime();
 838   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 839   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 840   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 841   _prev_collection_pause_end_ms += elapsed_time_ms;
 842 
 843   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
 844 }
 845 
 846 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 847   _mark_cleanup_start_sec = os::elapsedTime();
 848 }
 849 
 850 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 851   _last_young_gc = true;
 852   _in_marking_window = false;
 853 }
 854 
 855 void G1CollectorPolicy::record_concurrent_pause() {
 856   if (_stop_world_start > 0.0) {
 857     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 858     _trace_gen0_time_data.record_yield_time(yield_ms);
 859   }
 860 }
 861 
 862 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 863   if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
 864     return false;
 865   }
 866 
 867   size_t marking_initiating_used_threshold =
 868     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
 869   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 870   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 871 
 872   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
 873     if (gcs_are_young()) {
 874       ergo_verbose5(ErgoConcCycles,
 875         "request concurrent cycle initiation",
 876         ergo_format_reason("occupancy higher than threshold")
 877         ergo_format_byte("occupancy")
 878         ergo_format_byte("allocation request")
 879         ergo_format_byte_perc("threshold")
 880         ergo_format_str("source"),
 881         cur_used_bytes,
 882         alloc_byte_size,
 883         marking_initiating_used_threshold,
 884         (double) InitiatingHeapOccupancyPercent,
 885         source);
 886       return true;
 887     } else {
 888       ergo_verbose5(ErgoConcCycles,
 889         "do not request concurrent cycle initiation",
 890         ergo_format_reason("still doing mixed collections")
 891         ergo_format_byte("occupancy")
 892         ergo_format_byte("allocation request")
 893         ergo_format_byte_perc("threshold")
 894         ergo_format_str("source"),
 895         cur_used_bytes,
 896         alloc_byte_size,
 897         marking_initiating_used_threshold,
 898         (double) InitiatingHeapOccupancyPercent,
 899         source);
 900     }
 901   }
 902 
 903   return false;
 904 }
 905 
 906 // Anything below that is considered to be zero
 907 #define MIN_TIMER_GRANULARITY 0.0000001
 908 
 909 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms) {
 910   double end_time_sec = os::elapsedTime();
 911   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
 912          "otherwise, the subtraction below does not make sense");
 913   size_t rs_size =
 914             _cur_collection_pause_used_regions_at_start - cset_region_length();
 915   size_t cur_used_bytes = _g1->used();
 916   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 917   bool last_pause_included_initial_mark = false;
 918   bool update_stats = !_g1->evacuation_failed();
 919 
 920 #ifndef PRODUCT
 921   if (G1YoungSurvRateVerbose) {
 922     gclog_or_tty->print_cr("");
 923     _short_lived_surv_rate_group->print();
 924     // do that for any other surv rate groups too
 925   }
 926 #endif // PRODUCT
 927 
 928   last_pause_included_initial_mark = during_initial_mark_pause();
 929   if (last_pause_included_initial_mark) {
 930     record_concurrent_mark_init_end(0.0);
 931   } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
 932     // Note: this might have already been set, if during the last
 933     // pause we decided to start a cycle but at the beginning of
 934     // this pause we decided to postpone it. That's OK.
 935     set_initiate_conc_mark_if_possible();
 936   }
 937 
 938   _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
 939                           end_time_sec, false);
 940 
 941   size_t freed_bytes =
 942     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
 943   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
 944 
 945   double survival_fraction =
 946     (double)surviving_bytes/
 947     (double)_collection_set_bytes_used_before;
 948 
 949   if (update_stats) {
 950     _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
 951     // this is where we update the allocation rate of the application
 952     double app_time_ms =
 953       (phase_times()->_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
 954     if (app_time_ms < MIN_TIMER_GRANULARITY) {
 955       // This usually happens due to the timer not having the required
 956       // granularity. Some Linuxes are the usual culprits.
 957       // We'll just set it to something (arbitrarily) small.
 958       app_time_ms = 1.0;
 959     }
 960     // We maintain the invariant that all objects allocated by mutator
 961     // threads will be allocated out of eden regions. So, we can use
 962     // the eden region number allocated since the previous GC to
 963     // calculate the application's allocate rate. The only exception
 964     // to that is humongous objects that are allocated separately. But
 965     // given that humongous object allocations do not really affect
 966     // either the pause's duration nor when the next pause will take
 967     // place we can safely ignore them here.
 968     uint regions_allocated = eden_cset_region_length();
 969     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
 970     _alloc_rate_ms_seq->add(alloc_rate_ms);
 971 
 972     double interval_ms =
 973       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
 974     update_recent_gc_times(end_time_sec, pause_time_ms);
 975     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
 976     if (recent_avg_pause_time_ratio() < 0.0 ||
 977         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
 978 #ifndef PRODUCT
 979       // Dump info to allow post-facto debugging
 980       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
 981       gclog_or_tty->print_cr("-------------------------------------------");
 982       gclog_or_tty->print_cr("Recent GC Times (ms):");
 983       _recent_gc_times_ms->dump();
 984       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
 985       _recent_prev_end_times_for_all_gcs_sec->dump();
 986       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
 987                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
 988       // In debug mode, terminate the JVM if the user wants to debug at this point.
 989       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
 990 #endif  // !PRODUCT
 991       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
 992       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
 993       if (_recent_avg_pause_time_ratio < 0.0) {
 994         _recent_avg_pause_time_ratio = 0.0;
 995       } else {
 996         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
 997         _recent_avg_pause_time_ratio = 1.0;
 998       }
 999     }
1000   }
1001   bool new_in_marking_window = _in_marking_window;
1002   bool new_in_marking_window_im = false;
1003   if (during_initial_mark_pause()) {
1004     new_in_marking_window = true;
1005     new_in_marking_window_im = true;
1006   }
1007 
1008   if (_last_young_gc) {
1009     // This is supposed to to be the "last young GC" before we start
1010     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1011 
1012     if (!last_pause_included_initial_mark) {
1013       if (next_gc_should_be_mixed("start mixed GCs",
1014                                   "do not start mixed GCs")) {
1015         set_gcs_are_young(false);
1016       }
1017     } else {
1018       ergo_verbose0(ErgoMixedGCs,
1019                     "do not start mixed GCs",
1020                     ergo_format_reason("concurrent cycle is about to start"));
1021     }
1022     _last_young_gc = false;
1023   }
1024 
1025   if (!_last_gc_was_young) {
1026     // This is a mixed GC. Here we decide whether to continue doing
1027     // mixed GCs or not.
1028 
1029     if (!next_gc_should_be_mixed("continue mixed GCs",
1030                                  "do not continue mixed GCs")) {
1031       set_gcs_are_young(true);
1032     }
1033   }
1034 
1035   _short_lived_surv_rate_group->start_adding_regions();
1036   // do that for any other surv rate groupsx
1037 
1038   if (update_stats) {
1039     size_t diff = 0;
1040     if (_max_pending_cards >= _pending_cards) {
1041       diff = _max_pending_cards - _pending_cards;
1042     }
1043     _pending_card_diff_seq->add((double) diff);
1044 
1045     double cost_per_card_ms = 0.0;
1046     if (_pending_cards > 0) {
1047       cost_per_card_ms = phase_times()->_update_rs_time / (double) _pending_cards;
1048       _cost_per_card_ms_seq->add(cost_per_card_ms);
1049     }
1050 
1051     size_t cards_scanned = _g1->cards_scanned();
1052 
1053     double cost_per_entry_ms = 0.0;
1054     if (cards_scanned > 10) {
1055       cost_per_entry_ms = phase_times()->_scan_rs_time / (double) cards_scanned;
1056       if (_last_gc_was_young) {
1057         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1058       } else {
1059         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1060       }
1061     }
1062 
1063     if (_max_rs_lengths > 0) {
1064       double cards_per_entry_ratio =
1065         (double) cards_scanned / (double) _max_rs_lengths;
1066       if (_last_gc_was_young) {
1067         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1068       } else {
1069         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1070       }
1071     }
1072 
1073     // This is defensive. For a while _max_rs_lengths could get
1074     // smaller than _recorded_rs_lengths which was causing
1075     // rs_length_diff to get very large and mess up the RSet length
1076     // predictions. The reason was unsafe concurrent updates to the
1077     // _inc_cset_recorded_rs_lengths field which the code below guards
1078     // against (see CR 7118202). This bug has now been fixed (see CR
1079     // 7119027). However, I'm still worried that
1080     // _inc_cset_recorded_rs_lengths might still end up somewhat
1081     // inaccurate. The concurrent refinement thread calculates an
1082     // RSet's length concurrently with other CR threads updating it
1083     // which might cause it to calculate the length incorrectly (if,
1084     // say, it's in mid-coarsening). So I'll leave in the defensive
1085     // conditional below just in case.
1086     size_t rs_length_diff = 0;
1087     if (_max_rs_lengths > _recorded_rs_lengths) {
1088       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1089     }
1090     _rs_length_diff_seq->add((double) rs_length_diff);
1091 
1092     size_t copied_bytes = surviving_bytes;
1093     double cost_per_byte_ms = 0.0;
1094     if (copied_bytes > 0) {
1095       cost_per_byte_ms = phase_times()->_obj_copy_time / (double) copied_bytes;
1096       if (_in_marking_window) {
1097         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1098       } else {
1099         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1100       }
1101     }
1102 
1103     double all_other_time_ms = pause_time_ms -
1104       (phase_times()->_update_rs_time + phase_times()->_scan_rs_time + phase_times()->_obj_copy_time + phase_times()->_termination_time);
1105 
1106     double young_other_time_ms = 0.0;
1107     if (young_cset_region_length() > 0) {
1108       young_other_time_ms =
1109         phase_times()->_recorded_young_cset_choice_time_ms +
1110         phase_times()->_recorded_young_free_cset_time_ms;
1111       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1112                                           (double) young_cset_region_length());
1113     }
1114     double non_young_other_time_ms = 0.0;
1115     if (old_cset_region_length() > 0) {
1116       non_young_other_time_ms =
1117         phase_times()->_recorded_non_young_cset_choice_time_ms +
1118         phase_times()->_recorded_non_young_free_cset_time_ms;
1119 
1120       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1121                                             (double) old_cset_region_length());
1122     }
1123 
1124     double constant_other_time_ms = all_other_time_ms -
1125       (young_other_time_ms + non_young_other_time_ms);
1126     _constant_other_time_ms_seq->add(constant_other_time_ms);
1127 
1128     double survival_ratio = 0.0;
1129     if (_bytes_in_collection_set_before_gc > 0) {
1130       survival_ratio = (double) _bytes_copied_during_gc /
1131                                    (double) _bytes_in_collection_set_before_gc;
1132     }
1133 
1134     _pending_cards_seq->add((double) _pending_cards);
1135     _rs_lengths_seq->add((double) _max_rs_lengths);
1136   }
1137 
1138   _in_marking_window = new_in_marking_window;
1139   _in_marking_window_im = new_in_marking_window_im;
1140   _free_regions_at_end_of_collection = _g1->free_regions();
1141   update_young_list_target_length();
1142 
1143   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1144   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1145   adjust_concurrent_refinement(phase_times()->_update_rs_time, phase_times()->_update_rs_processed_buffers, update_rs_time_goal_ms);
1146 
1147   _collectionSetChooser->verify();
1148 }
1149 
1150 #define EXT_SIZE_FORMAT "%.1f%s"
1151 #define EXT_SIZE_PARAMS(bytes)                                  \
1152   byte_size_in_proper_unit((double)(bytes)),                    \
1153   proper_unit_for_byte_size((bytes))
1154 
1155 void G1CollectorPolicy::print_heap_transition() {
1156   if (G1Log::finer()) {
1157     YoungList* young_list = _g1->young_list();
1158     size_t eden_bytes = young_list->eden_used_bytes();
1159     size_t survivor_bytes = young_list->survivor_used_bytes();
1160     size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1161     size_t used = _g1->used();
1162     size_t capacity = _g1->capacity();
1163     size_t eden_capacity =
1164       (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1165 
1166     gclog_or_tty->print_cr(
1167       "   [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1168       "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1169       "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1170       EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1171       EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1172       EXT_SIZE_PARAMS(_prev_eden_capacity),
1173       EXT_SIZE_PARAMS(eden_bytes),
1174       EXT_SIZE_PARAMS(eden_capacity),
1175       EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1176       EXT_SIZE_PARAMS(survivor_bytes),
1177       EXT_SIZE_PARAMS(used_before_gc),
1178       EXT_SIZE_PARAMS(_capacity_before_gc),
1179       EXT_SIZE_PARAMS(used),
1180       EXT_SIZE_PARAMS(capacity));
1181 
1182     _prev_eden_capacity = eden_capacity;
1183   } else if (G1Log::fine()) {
1184     _g1->print_size_transition(gclog_or_tty,
1185                                _cur_collection_pause_used_at_start_bytes,
1186                                _g1->used(), _g1->capacity());
1187   }
1188 }
1189 
1190 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1191                                                      double update_rs_processed_buffers,
1192                                                      double goal_ms) {
1193   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1194   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1195 
1196   if (G1UseAdaptiveConcRefinement) {
1197     const int k_gy = 3, k_gr = 6;
1198     const double inc_k = 1.1, dec_k = 0.9;
1199 
1200     int g = cg1r->green_zone();
1201     if (update_rs_time > goal_ms) {
1202       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1203     } else {
1204       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1205         g = (int)MAX2(g * inc_k, g + 1.0);
1206       }
1207     }
1208     // Change the refinement threads params
1209     cg1r->set_green_zone(g);
1210     cg1r->set_yellow_zone(g * k_gy);
1211     cg1r->set_red_zone(g * k_gr);
1212     cg1r->reinitialize_threads();
1213 
1214     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1215     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1216                                     cg1r->yellow_zone());
1217     // Change the barrier params
1218     dcqs.set_process_completed_threshold(processing_threshold);
1219     dcqs.set_max_completed_queue(cg1r->red_zone());
1220   }
1221 
1222   int curr_queue_size = dcqs.completed_buffers_num();
1223   if (curr_queue_size >= cg1r->yellow_zone()) {
1224     dcqs.set_completed_queue_padding(curr_queue_size);
1225   } else {
1226     dcqs.set_completed_queue_padding(0);
1227   }
1228   dcqs.notify_if_necessary();
1229 }
1230 
1231 double
1232 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1233   size_t rs_length = predict_rs_length_diff();
1234   size_t card_num;
1235   if (gcs_are_young()) {
1236     card_num = predict_young_card_num(rs_length);
1237   } else {
1238     card_num = predict_non_young_card_num(rs_length);
1239   }
1240   return predict_base_elapsed_time_ms(pending_cards, card_num);
1241 }
1242 
1243 double
1244 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1245                                                 size_t scanned_cards) {
1246   return
1247     predict_rs_update_time_ms(pending_cards) +
1248     predict_rs_scan_time_ms(scanned_cards) +
1249     predict_constant_other_time_ms();
1250 }
1251 
1252 double
1253 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1254                                                   bool young) {
1255   size_t rs_length = hr->rem_set()->occupied();
1256   size_t card_num;
1257   if (gcs_are_young()) {
1258     card_num = predict_young_card_num(rs_length);
1259   } else {
1260     card_num = predict_non_young_card_num(rs_length);
1261   }
1262   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1263 
1264   double region_elapsed_time_ms =
1265     predict_rs_scan_time_ms(card_num) +
1266     predict_object_copy_time_ms(bytes_to_copy);
1267 
1268   if (young)
1269     region_elapsed_time_ms += predict_young_other_time_ms(1);
1270   else
1271     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1272 
1273   return region_elapsed_time_ms;
1274 }
1275 
1276 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1277   size_t bytes_to_copy;
1278   if (hr->is_marked())
1279     bytes_to_copy = hr->max_live_bytes();
1280   else {
1281     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1282     int age = hr->age_in_surv_rate_group();
1283     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1284     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1285   }
1286   return bytes_to_copy;
1287 }
1288 
1289 void
1290 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1291                                             uint survivor_cset_region_length) {
1292   _eden_cset_region_length     = eden_cset_region_length;
1293   _survivor_cset_region_length = survivor_cset_region_length;
1294   _old_cset_region_length      = 0;
1295 }
1296 
1297 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1298   _recorded_rs_lengths = rs_lengths;
1299 }
1300 
1301 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1302                                                double elapsed_ms) {
1303   _recent_gc_times_ms->add(elapsed_ms);
1304   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1305   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1306 }
1307 
1308 size_t G1CollectorPolicy::expansion_amount() {
1309   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1310   double threshold = _gc_overhead_perc;
1311   if (recent_gc_overhead > threshold) {
1312     // We will double the existing space, or take
1313     // G1ExpandByPercentOfAvailable % of the available expansion
1314     // space, whichever is smaller, bounded below by a minimum
1315     // expansion (unless that's all that's left.)
1316     const size_t min_expand_bytes = 1*M;
1317     size_t reserved_bytes = _g1->max_capacity();
1318     size_t committed_bytes = _g1->capacity();
1319     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1320     size_t expand_bytes;
1321     size_t expand_bytes_via_pct =
1322       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1323     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1324     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1325     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1326 
1327     ergo_verbose5(ErgoHeapSizing,
1328                   "attempt heap expansion",
1329                   ergo_format_reason("recent GC overhead higher than "
1330                                      "threshold after GC")
1331                   ergo_format_perc("recent GC overhead")
1332                   ergo_format_perc("threshold")
1333                   ergo_format_byte("uncommitted")
1334                   ergo_format_byte_perc("calculated expansion amount"),
1335                   recent_gc_overhead, threshold,
1336                   uncommitted_bytes,
1337                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1338 
1339     return expand_bytes;
1340   } else {
1341     return 0;
1342   }
1343 }
1344 
1345 class CountCSClosure: public HeapRegionClosure {
1346   G1CollectorPolicy* _g1_policy;
1347 public:
1348   CountCSClosure(G1CollectorPolicy* g1_policy) :
1349     _g1_policy(g1_policy) {}
1350   bool doHeapRegion(HeapRegion* r) {
1351     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
1352     return false;
1353   }
1354 };
1355 
1356 void G1CollectorPolicy::count_CS_bytes_used() {
1357   CountCSClosure cs_closure(this);
1358   _g1->collection_set_iterate(&cs_closure);
1359 }
1360 
1361 void G1CollectorPolicy::print_tracing_info() const {
1362   _trace_gen0_time_data.print();
1363   _trace_gen1_time_data.print();
1364 }
1365 
1366 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1367 #ifndef PRODUCT
1368   _short_lived_surv_rate_group->print_surv_rate_summary();
1369   // add this call for any other surv rate groups
1370 #endif // PRODUCT
1371 }
1372 
1373 #ifndef PRODUCT
1374 // for debugging, bit of a hack...
1375 static char*
1376 region_num_to_mbs(int length) {
1377   static char buffer[64];
1378   double bytes = (double) (length * HeapRegion::GrainBytes);
1379   double mbs = bytes / (double) (1024 * 1024);
1380   sprintf(buffer, "%7.2lfMB", mbs);
1381   return buffer;
1382 }
1383 #endif // PRODUCT
1384 
1385 uint G1CollectorPolicy::max_regions(int purpose) {
1386   switch (purpose) {
1387     case GCAllocForSurvived:
1388       return _max_survivor_regions;
1389     case GCAllocForTenured:
1390       return REGIONS_UNLIMITED;
1391     default:
1392       ShouldNotReachHere();
1393       return REGIONS_UNLIMITED;
1394   };
1395 }
1396 
1397 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1398   uint expansion_region_num = 0;
1399   if (GCLockerEdenExpansionPercent > 0) {
1400     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1401     double expansion_region_num_d = perc * (double) _young_list_target_length;
1402     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1403     // less than 1.0) we'll get 1.
1404     expansion_region_num = (uint) ceil(expansion_region_num_d);
1405   } else {
1406     assert(expansion_region_num == 0, "sanity");
1407   }
1408   _young_list_max_length = _young_list_target_length + expansion_region_num;
1409   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1410 }
1411 
1412 // Calculates survivor space parameters.
1413 void G1CollectorPolicy::update_survivors_policy() {
1414   double max_survivor_regions_d =
1415                  (double) _young_list_target_length / (double) SurvivorRatio;
1416   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1417   // smaller than 1.0) we'll get 1.
1418   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1419 
1420   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1421         HeapRegion::GrainWords * _max_survivor_regions);
1422 }
1423 
1424 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1425                                                      GCCause::Cause gc_cause) {
1426   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1427   if (!during_cycle) {
1428     ergo_verbose1(ErgoConcCycles,
1429                   "request concurrent cycle initiation",
1430                   ergo_format_reason("requested by GC cause")
1431                   ergo_format_str("GC cause"),
1432                   GCCause::to_string(gc_cause));
1433     set_initiate_conc_mark_if_possible();
1434     return true;
1435   } else {
1436     ergo_verbose1(ErgoConcCycles,
1437                   "do not request concurrent cycle initiation",
1438                   ergo_format_reason("concurrent cycle already in progress")
1439                   ergo_format_str("GC cause"),
1440                   GCCause::to_string(gc_cause));
1441     return false;
1442   }
1443 }
1444 
1445 void
1446 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1447   // We are about to decide on whether this pause will be an
1448   // initial-mark pause.
1449 
1450   // First, during_initial_mark_pause() should not be already set. We
1451   // will set it here if we have to. However, it should be cleared by
1452   // the end of the pause (it's only set for the duration of an
1453   // initial-mark pause).
1454   assert(!during_initial_mark_pause(), "pre-condition");
1455 
1456   if (initiate_conc_mark_if_possible()) {
1457     // We had noticed on a previous pause that the heap occupancy has
1458     // gone over the initiating threshold and we should start a
1459     // concurrent marking cycle. So we might initiate one.
1460 
1461     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1462     if (!during_cycle) {
1463       // The concurrent marking thread is not "during a cycle", i.e.,
1464       // it has completed the last one. So we can go ahead and
1465       // initiate a new cycle.
1466 
1467       set_during_initial_mark_pause();
1468       // We do not allow mixed GCs during marking.
1469       if (!gcs_are_young()) {
1470         set_gcs_are_young(true);
1471         ergo_verbose0(ErgoMixedGCs,
1472                       "end mixed GCs",
1473                       ergo_format_reason("concurrent cycle is about to start"));
1474       }
1475 
1476       // And we can now clear initiate_conc_mark_if_possible() as
1477       // we've already acted on it.
1478       clear_initiate_conc_mark_if_possible();
1479 
1480       ergo_verbose0(ErgoConcCycles,
1481                   "initiate concurrent cycle",
1482                   ergo_format_reason("concurrent cycle initiation requested"));
1483     } else {
1484       // The concurrent marking thread is still finishing up the
1485       // previous cycle. If we start one right now the two cycles
1486       // overlap. In particular, the concurrent marking thread might
1487       // be in the process of clearing the next marking bitmap (which
1488       // we will use for the next cycle if we start one). Starting a
1489       // cycle now will be bad given that parts of the marking
1490       // information might get cleared by the marking thread. And we
1491       // cannot wait for the marking thread to finish the cycle as it
1492       // periodically yields while clearing the next marking bitmap
1493       // and, if it's in a yield point, it's waiting for us to
1494       // finish. So, at this point we will not start a cycle and we'll
1495       // let the concurrent marking thread complete the last one.
1496       ergo_verbose0(ErgoConcCycles,
1497                     "do not initiate concurrent cycle",
1498                     ergo_format_reason("concurrent cycle already in progress"));
1499     }
1500   }
1501 }
1502 
1503 class KnownGarbageClosure: public HeapRegionClosure {
1504   G1CollectedHeap* _g1h;
1505   CollectionSetChooser* _hrSorted;
1506 
1507 public:
1508   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1509     _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1510 
1511   bool doHeapRegion(HeapRegion* r) {
1512     // We only include humongous regions in collection
1513     // sets when concurrent mark shows that their contained object is
1514     // unreachable.
1515 
1516     // Do we have any marking information for this region?
1517     if (r->is_marked()) {
1518       // We will skip any region that's currently used as an old GC
1519       // alloc region (we should not consider those for collection
1520       // before we fill them up).
1521       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1522         _hrSorted->add_region(r);
1523       }
1524     }
1525     return false;
1526   }
1527 };
1528 
1529 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1530   G1CollectedHeap* _g1h;
1531   CollectionSetChooser* _hrSorted;
1532   uint _marked_regions_added;
1533   size_t _reclaimable_bytes_added;
1534   uint _chunk_size;
1535   uint _cur_chunk_idx;
1536   uint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
1537 
1538   void get_new_chunk() {
1539     _cur_chunk_idx = _hrSorted->claim_array_chunk(_chunk_size);
1540     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
1541   }
1542   void add_region(HeapRegion* r) {
1543     if (_cur_chunk_idx == _cur_chunk_end) {
1544       get_new_chunk();
1545     }
1546     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
1547     _hrSorted->set_region(_cur_chunk_idx, r);
1548     _marked_regions_added++;
1549     _reclaimable_bytes_added += r->reclaimable_bytes();
1550     _cur_chunk_idx++;
1551   }
1552 
1553 public:
1554   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1555                            uint chunk_size) :
1556       _g1h(G1CollectedHeap::heap()),
1557       _hrSorted(hrSorted), _chunk_size(chunk_size),
1558       _marked_regions_added(0), _reclaimable_bytes_added(0),
1559       _cur_chunk_idx(0), _cur_chunk_end(0) { }
1560 
1561   bool doHeapRegion(HeapRegion* r) {
1562     // Do we have any marking information for this region?
1563     if (r->is_marked()) {
1564       // We will skip any region that's currently used as an old GC
1565       // alloc region (we should not consider those for collection
1566       // before we fill them up).
1567       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1568         add_region(r);
1569       }
1570     }
1571     return false;
1572   }
1573   uint marked_regions_added() { return _marked_regions_added; }
1574   size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
1575 };
1576 
1577 class ParKnownGarbageTask: public AbstractGangTask {
1578   CollectionSetChooser* _hrSorted;
1579   uint _chunk_size;
1580   G1CollectedHeap* _g1;
1581 public:
1582   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1583     AbstractGangTask("ParKnownGarbageTask"),
1584     _hrSorted(hrSorted), _chunk_size(chunk_size),
1585     _g1(G1CollectedHeap::heap()) { }
1586 
1587   void work(uint worker_id) {
1588     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1589 
1590     // Back to zero for the claim value.
1591     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1592                                          _g1->workers()->active_workers(),
1593                                          HeapRegion::InitialClaimValue);
1594     uint regions_added = parKnownGarbageCl.marked_regions_added();
1595     size_t reclaimable_bytes_added =
1596                                    parKnownGarbageCl.reclaimable_bytes_added();
1597     _hrSorted->update_totals(regions_added, reclaimable_bytes_added);
1598   }
1599 };
1600 
1601 void
1602 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1603   _collectionSetChooser->clear();
1604 
1605   uint region_num = _g1->n_regions();
1606   if (G1CollectedHeap::use_parallel_gc_threads()) {
1607     const uint OverpartitionFactor = 4;
1608     uint WorkUnit;
1609     // The use of MinChunkSize = 8 in the original code
1610     // causes some assertion failures when the total number of
1611     // region is less than 8.  The code here tries to fix that.
1612     // Should the original code also be fixed?
1613     if (no_of_gc_threads > 0) {
1614       const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1615       WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1616                       MinWorkUnit);
1617     } else {
1618       assert(no_of_gc_threads > 0,
1619         "The active gc workers should be greater than 0");
1620       // In a product build do something reasonable to avoid a crash.
1621       const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1622       WorkUnit =
1623         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1624              MinWorkUnit);
1625     }
1626     _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1627                                                            WorkUnit);
1628     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1629                                             (int) WorkUnit);
1630     _g1->workers()->run_task(&parKnownGarbageTask);
1631 
1632     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1633            "sanity check");
1634   } else {
1635     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1636     _g1->heap_region_iterate(&knownGarbagecl);
1637   }
1638 
1639   _collectionSetChooser->sort_regions();
1640 
1641   double end_sec = os::elapsedTime();
1642   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1643   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1644   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1645   _prev_collection_pause_end_ms += elapsed_time_ms;
1646   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1647 }
1648 
1649 // Add the heap region at the head of the non-incremental collection set
1650 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1651   assert(_inc_cset_build_state == Active, "Precondition");
1652   assert(!hr->is_young(), "non-incremental add of young region");
1653 
1654   assert(!hr->in_collection_set(), "should not already be in the CSet");
1655   hr->set_in_collection_set(true);
1656   hr->set_next_in_collection_set(_collection_set);
1657   _collection_set = hr;
1658   _collection_set_bytes_used_before += hr->used();
1659   _g1->register_region_with_in_cset_fast_test(hr);
1660   size_t rs_length = hr->rem_set()->occupied();
1661   _recorded_rs_lengths += rs_length;
1662   _old_cset_region_length += 1;
1663 }
1664 
1665 // Initialize the per-collection-set information
1666 void G1CollectorPolicy::start_incremental_cset_building() {
1667   assert(_inc_cset_build_state == Inactive, "Precondition");
1668 
1669   _inc_cset_head = NULL;
1670   _inc_cset_tail = NULL;
1671   _inc_cset_bytes_used_before = 0;
1672 
1673   _inc_cset_max_finger = 0;
1674   _inc_cset_recorded_rs_lengths = 0;
1675   _inc_cset_recorded_rs_lengths_diffs = 0;
1676   _inc_cset_predicted_elapsed_time_ms = 0.0;
1677   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1678   _inc_cset_build_state = Active;
1679 }
1680 
1681 void G1CollectorPolicy::finalize_incremental_cset_building() {
1682   assert(_inc_cset_build_state == Active, "Precondition");
1683   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1684 
1685   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1686   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1687   // that adds a new region to the CSet. Further updates by the
1688   // concurrent refinement thread that samples the young RSet lengths
1689   // are accumulated in the *_diffs fields. Here we add the diffs to
1690   // the "main" fields.
1691 
1692   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1693     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1694   } else {
1695     // This is defensive. The diff should in theory be always positive
1696     // as RSets can only grow between GCs. However, given that we
1697     // sample their size concurrently with other threads updating them
1698     // it's possible that we might get the wrong size back, which
1699     // could make the calculations somewhat inaccurate.
1700     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1701     if (_inc_cset_recorded_rs_lengths >= diffs) {
1702       _inc_cset_recorded_rs_lengths -= diffs;
1703     } else {
1704       _inc_cset_recorded_rs_lengths = 0;
1705     }
1706   }
1707   _inc_cset_predicted_elapsed_time_ms +=
1708                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1709 
1710   _inc_cset_recorded_rs_lengths_diffs = 0;
1711   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1712 }
1713 
1714 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1715   // This routine is used when:
1716   // * adding survivor regions to the incremental cset at the end of an
1717   //   evacuation pause,
1718   // * adding the current allocation region to the incremental cset
1719   //   when it is retired, and
1720   // * updating existing policy information for a region in the
1721   //   incremental cset via young list RSet sampling.
1722   // Therefore this routine may be called at a safepoint by the
1723   // VM thread, or in-between safepoints by mutator threads (when
1724   // retiring the current allocation region) or a concurrent
1725   // refine thread (RSet sampling).
1726 
1727   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
1728   size_t used_bytes = hr->used();
1729   _inc_cset_recorded_rs_lengths += rs_length;
1730   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1731   _inc_cset_bytes_used_before += used_bytes;
1732 
1733   // Cache the values we have added to the aggregated informtion
1734   // in the heap region in case we have to remove this region from
1735   // the incremental collection set, or it is updated by the
1736   // rset sampling code
1737   hr->set_recorded_rs_length(rs_length);
1738   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1739 }
1740 
1741 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1742                                                      size_t new_rs_length) {
1743   // Update the CSet information that is dependent on the new RS length
1744   assert(hr->is_young(), "Precondition");
1745   assert(!SafepointSynchronize::is_at_safepoint(),
1746                                                "should not be at a safepoint");
1747 
1748   // We could have updated _inc_cset_recorded_rs_lengths and
1749   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1750   // that atomically, as this code is executed by a concurrent
1751   // refinement thread, potentially concurrently with a mutator thread
1752   // allocating a new region and also updating the same fields. To
1753   // avoid the atomic operations we accumulate these updates on two
1754   // separate fields (*_diffs) and we'll just add them to the "main"
1755   // fields at the start of a GC.
1756 
1757   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1758   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1759   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1760 
1761   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1762   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
1763   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1764   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1765 
1766   hr->set_recorded_rs_length(new_rs_length);
1767   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1768 }
1769 
1770 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1771   assert(hr->is_young(), "invariant");
1772   assert(hr->young_index_in_cset() > -1, "should have already been set");
1773   assert(_inc_cset_build_state == Active, "Precondition");
1774 
1775   // We need to clear and set the cached recorded/cached collection set
1776   // information in the heap region here (before the region gets added
1777   // to the collection set). An individual heap region's cached values
1778   // are calculated, aggregated with the policy collection set info,
1779   // and cached in the heap region here (initially) and (subsequently)
1780   // by the Young List sampling code.
1781 
1782   size_t rs_length = hr->rem_set()->occupied();
1783   add_to_incremental_cset_info(hr, rs_length);
1784 
1785   HeapWord* hr_end = hr->end();
1786   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1787 
1788   assert(!hr->in_collection_set(), "invariant");
1789   hr->set_in_collection_set(true);
1790   assert( hr->next_in_collection_set() == NULL, "invariant");
1791 
1792   _g1->register_region_with_in_cset_fast_test(hr);
1793 }
1794 
1795 // Add the region at the RHS of the incremental cset
1796 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1797   // We should only ever be appending survivors at the end of a pause
1798   assert( hr->is_survivor(), "Logic");
1799 
1800   // Do the 'common' stuff
1801   add_region_to_incremental_cset_common(hr);
1802 
1803   // Now add the region at the right hand side
1804   if (_inc_cset_tail == NULL) {
1805     assert(_inc_cset_head == NULL, "invariant");
1806     _inc_cset_head = hr;
1807   } else {
1808     _inc_cset_tail->set_next_in_collection_set(hr);
1809   }
1810   _inc_cset_tail = hr;
1811 }
1812 
1813 // Add the region to the LHS of the incremental cset
1814 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1815   // Survivors should be added to the RHS at the end of a pause
1816   assert(!hr->is_survivor(), "Logic");
1817 
1818   // Do the 'common' stuff
1819   add_region_to_incremental_cset_common(hr);
1820 
1821   // Add the region at the left hand side
1822   hr->set_next_in_collection_set(_inc_cset_head);
1823   if (_inc_cset_head == NULL) {
1824     assert(_inc_cset_tail == NULL, "Invariant");
1825     _inc_cset_tail = hr;
1826   }
1827   _inc_cset_head = hr;
1828 }
1829 
1830 #ifndef PRODUCT
1831 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1832   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1833 
1834   st->print_cr("\nCollection_set:");
1835   HeapRegion* csr = list_head;
1836   while (csr != NULL) {
1837     HeapRegion* next = csr->next_in_collection_set();
1838     assert(csr->in_collection_set(), "bad CS");
1839     st->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1840                  HR_FORMAT_PARAMS(csr),
1841                  csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1842                  csr->age_in_surv_rate_group_cond());
1843     csr = next;
1844   }
1845 }
1846 #endif // !PRODUCT
1847 
1848 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1849                                                 const char* false_action_str) {
1850   CollectionSetChooser* cset_chooser = _collectionSetChooser;
1851   if (cset_chooser->is_empty()) {
1852     ergo_verbose0(ErgoMixedGCs,
1853                   false_action_str,
1854                   ergo_format_reason("candidate old regions not available"));
1855     return false;
1856   }
1857   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1858   size_t capacity_bytes = _g1->capacity();
1859   double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1860   double threshold = (double) G1HeapWastePercent;
1861   if (perc < threshold) {
1862     ergo_verbose4(ErgoMixedGCs,
1863               false_action_str,
1864               ergo_format_reason("reclaimable percentage lower than threshold")
1865               ergo_format_region("candidate old regions")
1866               ergo_format_byte_perc("reclaimable")
1867               ergo_format_perc("threshold"),
1868               cset_chooser->remaining_regions(),
1869               reclaimable_bytes, perc, threshold);
1870     return false;
1871   }
1872 
1873   ergo_verbose4(ErgoMixedGCs,
1874                 true_action_str,
1875                 ergo_format_reason("candidate old regions available")
1876                 ergo_format_region("candidate old regions")
1877                 ergo_format_byte_perc("reclaimable")
1878                 ergo_format_perc("threshold"),
1879                 cset_chooser->remaining_regions(),
1880                 reclaimable_bytes, perc, threshold);
1881   return true;
1882 }
1883 
1884 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
1885   // Set this here - in case we're not doing young collections.
1886   double non_young_start_time_sec = os::elapsedTime();
1887 
1888   YoungList* young_list = _g1->young_list();
1889   finalize_incremental_cset_building();
1890 
1891   guarantee(target_pause_time_ms > 0.0,
1892             err_msg("target_pause_time_ms = %1.6lf should be positive",
1893                     target_pause_time_ms));
1894   guarantee(_collection_set == NULL, "Precondition");
1895 
1896   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1897   double predicted_pause_time_ms = base_time_ms;
1898   double time_remaining_ms = target_pause_time_ms - base_time_ms;
1899 
1900   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1901                 "start choosing CSet",
1902                 ergo_format_ms("predicted base time")
1903                 ergo_format_ms("remaining time")
1904                 ergo_format_ms("target pause time"),
1905                 base_time_ms, time_remaining_ms, target_pause_time_ms);
1906 
1907   HeapRegion* hr;
1908   double young_start_time_sec = os::elapsedTime();
1909 
1910   _collection_set_bytes_used_before = 0;
1911   _last_gc_was_young = gcs_are_young() ? true : false;
1912 
1913   if (_last_gc_was_young) {
1914     _trace_gen0_time_data.increment_young_collection_count();
1915   } else {
1916     _trace_gen0_time_data.increment_mixed_collection_count();
1917   }
1918 
1919   // The young list is laid with the survivor regions from the previous
1920   // pause are appended to the RHS of the young list, i.e.
1921   //   [Newly Young Regions ++ Survivors from last pause].
1922 
1923   uint survivor_region_length = young_list->survivor_length();
1924   uint eden_region_length = young_list->length() - survivor_region_length;
1925   init_cset_region_lengths(eden_region_length, survivor_region_length);
1926   hr = young_list->first_survivor_region();
1927   while (hr != NULL) {
1928     assert(hr->is_survivor(), "badly formed young list");
1929     hr->set_young();
1930     hr = hr->get_next_young_region();
1931   }
1932 
1933   // Clear the fields that point to the survivor list - they are all young now.
1934   young_list->clear_survivors();
1935 
1936   _collection_set = _inc_cset_head;
1937   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1938   time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
1939   predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1940 
1941   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1942                 "add young regions to CSet",
1943                 ergo_format_region("eden")
1944                 ergo_format_region("survivors")
1945                 ergo_format_ms("predicted young region time"),
1946                 eden_region_length, survivor_region_length,
1947                 _inc_cset_predicted_elapsed_time_ms);
1948 
1949   // The number of recorded young regions is the incremental
1950   // collection set's current size
1951   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1952 
1953   double young_end_time_sec = os::elapsedTime();
1954   phase_times()->_recorded_young_cset_choice_time_ms =
1955     (young_end_time_sec - young_start_time_sec) * 1000.0;
1956 
1957   // We are doing young collections so reset this.
1958   non_young_start_time_sec = young_end_time_sec;
1959 
1960   if (!gcs_are_young()) {
1961     CollectionSetChooser* cset_chooser = _collectionSetChooser;
1962     cset_chooser->verify();
1963     const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
1964     const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
1965 
1966     uint expensive_region_num = 0;
1967     bool check_time_remaining = adaptive_young_list_length();
1968     HeapRegion* hr = cset_chooser->peek();
1969     while (hr != NULL) {
1970       if (old_cset_region_length() >= max_old_cset_length) {
1971         // Added maximum number of old regions to the CSet.
1972         ergo_verbose2(ErgoCSetConstruction,
1973                       "finish adding old regions to CSet",
1974                       ergo_format_reason("old CSet region num reached max")
1975                       ergo_format_region("old")
1976                       ergo_format_region("max"),
1977                       old_cset_region_length(), max_old_cset_length);
1978         break;
1979       }
1980 
1981       double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
1982       if (check_time_remaining) {
1983         if (predicted_time_ms > time_remaining_ms) {
1984           // Too expensive for the current CSet.
1985 
1986           if (old_cset_region_length() >= min_old_cset_length) {
1987             // We have added the minimum number of old regions to the CSet,
1988             // we are done with this CSet.
1989             ergo_verbose4(ErgoCSetConstruction,
1990                           "finish adding old regions to CSet",
1991                           ergo_format_reason("predicted time is too high")
1992                           ergo_format_ms("predicted time")
1993                           ergo_format_ms("remaining time")
1994                           ergo_format_region("old")
1995                           ergo_format_region("min"),
1996                           predicted_time_ms, time_remaining_ms,
1997                           old_cset_region_length(), min_old_cset_length);
1998             break;
1999           }
2000 
2001           // We'll add it anyway given that we haven't reached the
2002           // minimum number of old regions.
2003           expensive_region_num += 1;
2004         }
2005       } else {
2006         if (old_cset_region_length() >= min_old_cset_length) {
2007           // In the non-auto-tuning case, we'll finish adding regions
2008           // to the CSet if we reach the minimum.
2009           ergo_verbose2(ErgoCSetConstruction,
2010                         "finish adding old regions to CSet",
2011                         ergo_format_reason("old CSet region num reached min")
2012                         ergo_format_region("old")
2013                         ergo_format_region("min"),
2014                         old_cset_region_length(), min_old_cset_length);
2015           break;
2016         }
2017       }
2018 
2019       // We will add this region to the CSet.
2020       time_remaining_ms -= predicted_time_ms;
2021       predicted_pause_time_ms += predicted_time_ms;
2022       cset_chooser->remove_and_move_to_next(hr);
2023       _g1->old_set_remove(hr);
2024       add_old_region_to_cset(hr);
2025 
2026       hr = cset_chooser->peek();
2027     }
2028     if (hr == NULL) {
2029       ergo_verbose0(ErgoCSetConstruction,
2030                     "finish adding old regions to CSet",
2031                     ergo_format_reason("candidate old regions not available"));
2032     }
2033 
2034     if (expensive_region_num > 0) {
2035       // We print the information once here at the end, predicated on
2036       // whether we added any apparently expensive regions or not, to
2037       // avoid generating output per region.
2038       ergo_verbose4(ErgoCSetConstruction,
2039                     "added expensive regions to CSet",
2040                     ergo_format_reason("old CSet region num not reached min")
2041                     ergo_format_region("old")
2042                     ergo_format_region("expensive")
2043                     ergo_format_region("min")
2044                     ergo_format_ms("remaining time"),
2045                     old_cset_region_length(),
2046                     expensive_region_num,
2047                     min_old_cset_length,
2048                     time_remaining_ms);
2049     }
2050 
2051     cset_chooser->verify();
2052   }
2053 
2054   stop_incremental_cset_building();
2055 
2056   count_CS_bytes_used();
2057 
2058   ergo_verbose5(ErgoCSetConstruction,
2059                 "finish choosing CSet",
2060                 ergo_format_region("eden")
2061                 ergo_format_region("survivors")
2062                 ergo_format_region("old")
2063                 ergo_format_ms("predicted pause time")
2064                 ergo_format_ms("target pause time"),
2065                 eden_region_length, survivor_region_length,
2066                 old_cset_region_length(),
2067                 predicted_pause_time_ms, target_pause_time_ms);
2068 
2069   double non_young_end_time_sec = os::elapsedTime();
2070   phase_times()->_recorded_non_young_cset_choice_time_ms =
2071     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
2072 }
2073 
2074 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2075   if(TraceGen0Time) {
2076     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2077   }
2078 }
2079 
2080 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2081   if(TraceGen0Time) {
2082     _all_yield_times_ms.add(yield_time_ms);
2083   }
2084 }
2085 
2086 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2087   if(TraceGen0Time) {
2088     _total.add(pause_time_ms);
2089     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2090     _root_region_scan_wait.add(phase_times->_root_region_scan_wait_time_ms);
2091     _parallel.add(phase_times->_cur_collection_par_time_ms);
2092     _ext_root_scan.add(phase_times->_ext_root_scan_time);
2093     _satb_filtering.add(phase_times->_satb_filtering_time);
2094     _update_rs.add(phase_times->_update_rs_time);
2095     _scan_rs.add(phase_times->_scan_rs_time);
2096     _obj_copy.add(phase_times->_obj_copy_time);
2097     _termination.add(phase_times->_termination_time);
2098 
2099     double parallel_known_time = phase_times->_ext_root_scan_time +
2100       phase_times->_satb_filtering_time +
2101       phase_times->_update_rs_time +
2102       phase_times->_scan_rs_time +
2103       phase_times->_obj_copy_time +
2104       + phase_times->_termination_time;
2105 
2106     double parallel_other_time = phase_times->_cur_collection_par_time_ms - parallel_known_time;
2107     _parallel_other.add(parallel_other_time);
2108     _clear_ct.add(phase_times->_cur_clear_ct_time_ms);
2109   }
2110 }
2111 
2112 void TraceGen0TimeData::increment_young_collection_count() {
2113   if(TraceGen0Time) {
2114     ++_young_pause_num;
2115   }
2116 }
2117 
2118 void TraceGen0TimeData::increment_mixed_collection_count() {
2119   if(TraceGen0Time) {
2120     ++_mixed_pause_num;
2121   }
2122 }
2123 
2124 void TraceGen0TimeData::print_summary(const char* str,
2125                                       const NumberSeq* seq) const {
2126   double sum = seq->sum();
2127   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2128                 str, sum / 1000.0, seq->avg());
2129 }
2130 
2131 void TraceGen0TimeData::print_summary_sd(const char* str,
2132                                          const NumberSeq* seq) const {
2133   print_summary(str, seq);
2134   gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2135                 "(num", seq->num(), seq->sd(), seq->maximum());
2136 }
2137 
2138 void TraceGen0TimeData::print() const {
2139   if (!TraceGen0Time) {
2140     return;
2141   }
2142 
2143   gclog_or_tty->print_cr("ALL PAUSES");
2144   print_summary_sd("   Total", &_total);
2145   gclog_or_tty->print_cr("");
2146   gclog_or_tty->print_cr("");
2147   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2148   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2149   gclog_or_tty->print_cr("");
2150 
2151   gclog_or_tty->print_cr("EVACUATION PAUSES");
2152 
2153   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2154     gclog_or_tty->print_cr("none");
2155   } else {
2156     print_summary_sd("   Evacuation Pauses", &_total);
2157     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2158     print_summary("      Parallel Time", &_parallel);
2159     print_summary("         Ext Root Scanning", &_ext_root_scan);
2160     print_summary("         SATB Filtering", &_satb_filtering);
2161     print_summary("         Update RS", &_update_rs);
2162     print_summary("         Scan RS", &_scan_rs);
2163     print_summary("         Object Copy", &_obj_copy);
2164     print_summary("         Termination", &_termination);
2165     print_summary("         Parallel Other", &_parallel_other);
2166     print_summary("      Clear CT", &_clear_ct);
2167     print_summary("      Other", &_other);
2168   }
2169   gclog_or_tty->print_cr("");
2170 
2171   gclog_or_tty->print_cr("MISC");
2172   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2173   print_summary_sd("   Yields", &_all_yield_times_ms);
2174 }
2175 
2176 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2177   if (TraceGen1Time) {
2178     _all_full_gc_times.add(full_gc_time_ms);
2179   }
2180 }
2181 
2182 void TraceGen1TimeData::print() const {
2183   if (!TraceGen1Time) {
2184     return;
2185   }
2186 
2187   if (_all_full_gc_times.num() > 0) {
2188     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2189       _all_full_gc_times.num(),
2190       _all_full_gc_times.sum() / 1000.0);
2191     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2192     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2193       _all_full_gc_times.sd(),
2194       _all_full_gc_times.maximum());
2195   }
2196 }