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   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  94   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  95   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  96   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  97   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  98   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  99   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 100   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
 101   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 102   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
 103   _non_young_other_cost_per_region_ms_seq(
 104                                          new TruncatedSeq(TruncatedSeqLength)),
 105 
 106   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
 107   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
 108 
 109   _pause_time_target_ms((double) MaxGCPauseMillis),
 110 
 111   _gcs_are_young(true),
 112 
 113   _during_marking(false),
 114   _in_marking_window(false),
 115   _in_marking_window_im(false),
 116 
 117   _recent_prev_end_times_for_all_gcs_sec(
 118                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
 119 
 120   _recent_avg_pause_time_ratio(0.0),
 121 
 122   _initiate_conc_mark_if_possible(false),
 123   _during_initial_mark_pause(false),
 124   _last_young_gc(false),
 125   _last_gc_was_young(false),
 126 
 127   _eden_bytes_before_gc(0),
 128   _survivor_bytes_before_gc(0),
 129   _capacity_before_gc(0),
 130 
 131   _eden_cset_region_length(0),
 132   _survivor_cset_region_length(0),
 133   _old_cset_region_length(0),
 134 
 135   _collection_set(NULL),
 136   _collection_set_bytes_used_before(0),
 137 
 138   // Incremental CSet attributes
 139   _inc_cset_build_state(Inactive),
 140   _inc_cset_head(NULL),
 141   _inc_cset_tail(NULL),
 142   _inc_cset_bytes_used_before(0),
 143   _inc_cset_max_finger(NULL),
 144   _inc_cset_recorded_rs_lengths(0),
 145   _inc_cset_recorded_rs_lengths_diffs(0),
 146   _inc_cset_predicted_elapsed_time_ms(0.0),
 147   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
 148 
 149 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 150 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 151 #endif // _MSC_VER
 152 
 153   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
 154                                                  G1YoungSurvRateNumRegionsSummary)),
 155   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
 156                                               G1YoungSurvRateNumRegionsSummary)),
 157   // add here any more surv rate groups
 158   _recorded_survivor_regions(0),
 159   _recorded_survivor_head(NULL),
 160   _recorded_survivor_tail(NULL),
 161   _survivors_age_table(true),
 162 
 163   _gc_overhead_perc(0.0) {
 164 
 165   // Set up the region size and associated fields. Given that the
 166   // policy is created before the heap, we have to set this up here,
 167   // so it's done as soon as possible.
 168   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
 169   HeapRegionRemSet::setup_remset_size();
 170 
 171   G1ErgoVerbose::initialize();
 172   if (PrintAdaptiveSizePolicy) {
 173     // Currently, we only use a single switch for all the heuristics.
 174     G1ErgoVerbose::set_enabled(true);
 175     // Given that we don't currently have a verboseness level
 176     // parameter, we'll hardcode this to high. This can be easily
 177     // changed in the future.
 178     G1ErgoVerbose::set_level(ErgoHigh);
 179   } else {
 180     G1ErgoVerbose::set_enabled(false);
 181   }
 182 
 183   // Verify PLAB sizes
 184   const size_t region_size = HeapRegion::GrainWords;
 185   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
 186     char buffer[128];
 187     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
 188                  OldPLABSize > region_size ? "Old" : "Young", region_size);
 189     vm_exit_during_initialization(buffer);
 190   }
 191 
 192   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 193   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 194 
 195   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);
 196 
 197   int index = MIN2(_parallel_gc_threads - 1, 7);
 198 
 199   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
 200   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
 201   _young_cards_per_entry_ratio_seq->add(
 202                                   young_cards_per_entry_ratio_defaults[index]);
 203   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
 204   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
 205   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
 206   _young_other_cost_per_region_ms_seq->add(
 207                                young_other_cost_per_region_ms_defaults[index]);
 208   _non_young_other_cost_per_region_ms_seq->add(
 209                            non_young_other_cost_per_region_ms_defaults[index]);
 210 
 211   // Below, we might need to calculate the pause time target based on
 212   // the pause interval. When we do so we are going to give G1 maximum
 213   // flexibility and allow it to do pauses when it needs to. So, we'll
 214   // arrange that the pause interval to be pause time target + 1 to
 215   // ensure that a) the pause time target is maximized with respect to
 216   // the pause interval and b) we maintain the invariant that pause
 217   // time target < pause interval. If the user does not want this
 218   // maximum flexibility, they will have to set the pause interval
 219   // explicitly.
 220 
 221   // First make sure that, if either parameter is set, its value is
 222   // reasonable.
 223   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 224     if (MaxGCPauseMillis < 1) {
 225       vm_exit_during_initialization("MaxGCPauseMillis should be "
 226                                     "greater than 0");
 227     }
 228   }
 229   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 230     if (GCPauseIntervalMillis < 1) {
 231       vm_exit_during_initialization("GCPauseIntervalMillis should be "
 232                                     "greater than 0");
 233     }
 234   }
 235 
 236   // Then, if the pause time target parameter was not set, set it to
 237   // the default value.
 238   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
 239     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 240       // The default pause time target in G1 is 200ms
 241       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
 242     } else {
 243       // We do not allow the pause interval to be set without the
 244       // pause time target
 245       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
 246                                     "without setting MaxGCPauseMillis");
 247     }
 248   }
 249 
 250   // Then, if the interval parameter was not set, set it according to
 251   // the pause time target (this will also deal with the case when the
 252   // pause time target is the default value).
 253   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
 254     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
 255   }
 256 
 257   // Finally, make sure that the two parameters are consistent.
 258   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
 259     char buffer[256];
 260     jio_snprintf(buffer, 256,
 261                  "MaxGCPauseMillis (%u) should be less than "
 262                  "GCPauseIntervalMillis (%u)",
 263                  MaxGCPauseMillis, GCPauseIntervalMillis);
 264     vm_exit_during_initialization(buffer);
 265   }
 266 
 267   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
 268   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
 269   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
 270 
 271   intx confidence_perc = G1ConfidencePercent;
 272   // Put an artificial ceiling on this so that it's not set to a silly value.
 273   if (confidence_perc > 100) {
 274     confidence_perc = 100;
 275     warning("G1ConfidencePercent is set to a value that is too large, "
 276             "it's been updated to %u", confidence_perc);
 277   }
 278   // Put an artificial flooring on this so that it's not set to a silly value.
 279   if (confidence_perc < 0) {
 280     confidence_perc = 0;
 281     warning("G1ConfidencePercent is set to a value that is too small, "
 282             "it's been updated to %u", confidence_perc);
 283   }
 284   _sigma = (double) confidence_perc / 100.0;
 285 
 286   // start conservatively (around 50ms is about right)
 287   _concurrent_mark_remark_times_ms->add(0.05);
 288   _concurrent_mark_cleanup_times_ms->add(0.20);
 289   _tenuring_threshold = MaxTenuringThreshold;
 290   // _max_survivor_regions will be calculated by
 291   // update_young_list_target_length() during initialization.
 292   _max_survivor_regions = 0;
 293 
 294   assert(GCTimeRatio > 0,
 295          "we should have set it to a default value set_g1_gc_flags() "
 296          "if a user set it to 0");
 297   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
 298 
 299   uintx reserve_perc = G1ReservePercent;
 300   // Put an artificial ceiling on this so that it's not set to a silly value.
 301   if (reserve_perc > 50) {
 302     reserve_perc = 50;
 303     warning("G1ReservePercent is set to a value that is too large, "
 304             "it's been updated to %u", reserve_perc);
 305   }
 306   _reserve_factor = (double) reserve_perc / 100.0;
 307   // This will be set when the heap is expanded
 308   // for the first time during initialization.
 309   _reserve_regions = 0;
 310 
 311   initialize_all();
 312   _collectionSetChooser = new CollectionSetChooser();
 313   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
 314 }
 315 
 316 void G1CollectorPolicy::initialize_flags() {
 317   set_min_alignment(HeapRegion::GrainBytes);
 318   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
 319   if (SurvivorRatio < 1) {
 320     vm_exit_during_initialization("Invalid survivor ratio specified");
 321   }
 322   CollectorPolicy::initialize_flags();
 323 }
 324 
 325 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
 326   assert(G1NewSizePercent <= G1MaxNewSizePercent, "Min larger than max");
 327   assert(G1NewSizePercent > 0 && G1NewSizePercent < 100, "Min out of bounds");
 328   assert(G1MaxNewSizePercent > 0 && G1MaxNewSizePercent < 100, "Max out of bounds");
 329 
 330   if (FLAG_IS_CMDLINE(NewRatio)) {
 331     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
 332       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
 333     } else {
 334       _sizer_kind = SizerNewRatio;
 335       _adaptive_size = false;
 336       return;
 337     }
 338   }
 339 
 340   if (FLAG_IS_CMDLINE(NewSize)) {
 341     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
 342                                      1U);
 343     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 344       _max_desired_young_length =
 345                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 346                                   1U);
 347       _sizer_kind = SizerMaxAndNewSize;
 348       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
 349     } else {
 350       _sizer_kind = SizerNewSizeOnly;
 351     }
 352   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
 353     _max_desired_young_length =
 354                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 355                                   1U);
 356     _sizer_kind = SizerMaxNewSizeOnly;
 357   }
 358 }
 359 
 360 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
 361   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;
 362   return MAX2(1U, default_value);
 363 }
 364 
 365 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
 366   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;
 367   return MAX2(1U, default_value);
 368 }
 369 
 370 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
 371   assert(new_number_of_heap_regions > 0, "Heap must be initialized");
 372 
 373   switch (_sizer_kind) {
 374     case SizerDefaults:
 375       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
 376       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
 377       break;
 378     case SizerNewSizeOnly:
 379       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
 380       _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
 381       break;
 382     case SizerMaxNewSizeOnly:
 383       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
 384       _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
 385       break;
 386     case SizerMaxAndNewSize:
 387       // Do nothing. Values set on the command line, don't update them at runtime.
 388       break;
 389     case SizerNewRatio:
 390       _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
 391       _max_desired_young_length = _min_desired_young_length;
 392       break;
 393     default:
 394       ShouldNotReachHere();
 395   }
 396 
 397   assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
 398 }
 399 
 400 void G1CollectorPolicy::init() {
 401   // Set aside an initial future to_space.
 402   _g1 = G1CollectedHeap::heap();
 403 
 404   assert(Heap_lock->owned_by_self(), "Locking discipline.");
 405 
 406   initialize_gc_policy_counters();
 407 
 408   if (adaptive_young_list_length()) {
 409     _young_list_fixed_length = 0;
 410   } else {
 411     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
 412   }
 413   _free_regions_at_end_of_collection = _g1->free_regions();
 414   update_young_list_target_length();
 415   _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
 416 
 417   // We may immediately start allocating regions and placing them on the
 418   // collection set list. Initialize the per-collection set info
 419   start_incremental_cset_building();
 420 }
 421 
 422 // Create the jstat counters for the policy.
 423 void G1CollectorPolicy::initialize_gc_policy_counters() {
 424   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
 425 }
 426 
 427 bool G1CollectorPolicy::predict_will_fit(uint young_length,
 428                                          double base_time_ms,
 429                                          uint base_free_regions,
 430                                          double target_pause_time_ms) {
 431   if (young_length >= base_free_regions) {
 432     // end condition 1: not enough space for the young regions
 433     return false;
 434   }
 435 
 436   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 437   size_t bytes_to_copy =
 438                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 439   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
 440   double young_other_time_ms = predict_young_other_time_ms(young_length);
 441   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 442   if (pause_time_ms > target_pause_time_ms) {
 443     // end condition 2: prediction is over the target pause time
 444     return false;
 445   }
 446 
 447   size_t free_bytes =
 448                    (base_free_regions - young_length) * HeapRegion::GrainBytes;
 449   if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
 450     // end condition 3: out-of-space (conservatively!)
 451     return false;
 452   }
 453 
 454   // success!
 455   return true;
 456 }
 457 
 458 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
 459   // re-calculate the necessary reserve
 460   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 461   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 462   // smaller than 1.0) we'll get 1.
 463   _reserve_regions = (uint) ceil(reserve_regions_d);
 464 
 465   _young_gen_sizer->heap_size_changed(new_number_of_regions);
 466 }
 467 
 468 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
 469                                                        uint base_min_length) {
 470   uint desired_min_length = 0;
 471   if (adaptive_young_list_length()) {
 472     if (_alloc_rate_ms_seq->num() > 3) {
 473       double now_sec = os::elapsedTime();
 474       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 475       double alloc_rate_ms = predict_alloc_rate_ms();
 476       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 477     } else {
 478       // otherwise we don't have enough info to make the prediction
 479     }
 480   }
 481   desired_min_length += base_min_length;
 482   // make sure we don't go below any user-defined minimum bound
 483   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
 484 }
 485 
 486 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
 487   // Here, we might want to also take into account any additional
 488   // constraints (i.e., user-defined minimum bound). Currently, we
 489   // effectively don't set this bound.
 490   return _young_gen_sizer->max_desired_young_length();
 491 }
 492 
 493 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
 494   if (rs_lengths == (size_t) -1) {
 495     // if it's set to the default value (-1), we should predict it;
 496     // otherwise, use the given value.
 497     rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
 498   }
 499 
 500   // Calculate the absolute and desired min bounds.
 501 
 502   // This is how many young regions we already have (currently: the survivors).
 503   uint base_min_length = recorded_survivor_regions();
 504   // This is the absolute minimum young length, which ensures that we
 505   // can allocate one eden region in the worst-case.
 506   uint absolute_min_length = base_min_length + 1;
 507   uint desired_min_length =
 508                      calculate_young_list_desired_min_length(base_min_length);
 509   if (desired_min_length < absolute_min_length) {
 510     desired_min_length = absolute_min_length;
 511   }
 512 
 513   // Calculate the absolute and desired max bounds.
 514 
 515   // We will try our best not to "eat" into the reserve.
 516   uint absolute_max_length = 0;
 517   if (_free_regions_at_end_of_collection > _reserve_regions) {
 518     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 519   }
 520   uint desired_max_length = calculate_young_list_desired_max_length();
 521   if (desired_max_length > absolute_max_length) {
 522     desired_max_length = absolute_max_length;
 523   }
 524 
 525   uint young_list_target_length = 0;
 526   if (adaptive_young_list_length()) {
 527     if (gcs_are_young()) {
 528       young_list_target_length =
 529                         calculate_young_list_target_length(rs_lengths,
 530                                                            base_min_length,
 531                                                            desired_min_length,
 532                                                            desired_max_length);
 533       _rs_lengths_prediction = rs_lengths;
 534     } else {
 535       // Don't calculate anything and let the code below bound it to
 536       // the desired_min_length, i.e., do the next GC as soon as
 537       // possible to maximize how many old regions we can add to it.
 538     }
 539   } else {
 540     // The user asked for a fixed young gen so we'll fix the young gen
 541     // whether the next GC is young or mixed.
 542     young_list_target_length = _young_list_fixed_length;
 543   }
 544 
 545   // Make sure we don't go over the desired max length, nor under the
 546   // desired min length. In case they clash, desired_min_length wins
 547   // which is why that test is second.
 548   if (young_list_target_length > desired_max_length) {
 549     young_list_target_length = desired_max_length;
 550   }
 551   if (young_list_target_length < desired_min_length) {
 552     young_list_target_length = desired_min_length;
 553   }
 554 
 555   assert(young_list_target_length > recorded_survivor_regions(),
 556          "we should be able to allocate at least one eden region");
 557   assert(young_list_target_length >= absolute_min_length, "post-condition");
 558   _young_list_target_length = young_list_target_length;
 559 
 560   update_max_gc_locker_expansion();
 561 }
 562 
 563 uint
 564 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
 565                                                      uint base_min_length,
 566                                                      uint desired_min_length,
 567                                                      uint desired_max_length) {
 568   assert(adaptive_young_list_length(), "pre-condition");
 569   assert(gcs_are_young(), "only call this for young GCs");
 570 
 571   // In case some edge-condition makes the desired max length too small...
 572   if (desired_max_length <= desired_min_length) {
 573     return desired_min_length;
 574   }
 575 
 576   // We'll adjust min_young_length and max_young_length not to include
 577   // the already allocated young regions (i.e., so they reflect the
 578   // min and max eden regions we'll allocate). The base_min_length
 579   // will be reflected in the predictions by the
 580   // survivor_regions_evac_time prediction.
 581   assert(desired_min_length > base_min_length, "invariant");
 582   uint min_young_length = desired_min_length - base_min_length;
 583   assert(desired_max_length > base_min_length, "invariant");
 584   uint max_young_length = desired_max_length - base_min_length;
 585 
 586   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 587   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 588   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
 589   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
 590   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
 591   double base_time_ms =
 592     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 593     survivor_regions_evac_time;
 594   uint available_free_regions = _free_regions_at_end_of_collection;
 595   uint base_free_regions = 0;
 596   if (available_free_regions > _reserve_regions) {
 597     base_free_regions = available_free_regions - _reserve_regions;
 598   }
 599 
 600   // Here, we will make sure that the shortest young length that
 601   // makes sense fits within the target pause time.
 602 
 603   if (predict_will_fit(min_young_length, base_time_ms,
 604                        base_free_regions, target_pause_time_ms)) {
 605     // The shortest young length will fit into the target pause time;
 606     // we'll now check whether the absolute maximum number of young
 607     // regions will fit in the target pause time. If not, we'll do
 608     // a binary search between min_young_length and max_young_length.
 609     if (predict_will_fit(max_young_length, base_time_ms,
 610                          base_free_regions, target_pause_time_ms)) {
 611       // The maximum young length will fit into the target pause time.
 612       // We are done so set min young length to the maximum length (as
 613       // the result is assumed to be returned in min_young_length).
 614       min_young_length = max_young_length;
 615     } else {
 616       // The maximum possible number of young regions will not fit within
 617       // the target pause time so we'll search for the optimal
 618       // length. The loop invariants are:
 619       //
 620       // min_young_length < max_young_length
 621       // min_young_length is known to fit into the target pause time
 622       // max_young_length is known not to fit into the target pause time
 623       //
 624       // Going into the loop we know the above hold as we've just
 625       // checked them. Every time around the loop we check whether
 626       // the middle value between min_young_length and
 627       // max_young_length fits into the target pause time. If it
 628       // does, it becomes the new min. If it doesn't, it becomes
 629       // the new max. This way we maintain the loop invariants.
 630 
 631       assert(min_young_length < max_young_length, "invariant");
 632       uint diff = (max_young_length - min_young_length) / 2;
 633       while (diff > 0) {
 634         uint young_length = min_young_length + diff;
 635         if (predict_will_fit(young_length, base_time_ms,
 636                              base_free_regions, target_pause_time_ms)) {
 637           min_young_length = young_length;
 638         } else {
 639           max_young_length = young_length;
 640         }
 641         assert(min_young_length <  max_young_length, "invariant");
 642         diff = (max_young_length - min_young_length) / 2;
 643       }
 644       // The results is min_young_length which, according to the
 645       // loop invariants, should fit within the target pause time.
 646 
 647       // These are the post-conditions of the binary search above:
 648       assert(min_young_length < max_young_length,
 649              "otherwise we should have discovered that max_young_length "
 650              "fits into the pause target and not done the binary search");
 651       assert(predict_will_fit(min_young_length, base_time_ms,
 652                               base_free_regions, target_pause_time_ms),
 653              "min_young_length, the result of the binary search, should "
 654              "fit into the pause target");
 655       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 656                                base_free_regions, target_pause_time_ms),
 657              "min_young_length, the result of the binary search, should be "
 658              "optimal, so no larger length should fit into the pause target");
 659     }
 660   } else {
 661     // Even the minimum length doesn't fit into the pause time
 662     // target, return it as the result nevertheless.
 663   }
 664   return base_min_length + min_young_length;
 665 }
 666 
 667 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
 668   double survivor_regions_evac_time = 0.0;
 669   for (HeapRegion * r = _recorded_survivor_head;
 670        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
 671        r = r->get_next_young_region()) {
 672     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());
 673   }
 674   return survivor_regions_evac_time;
 675 }
 676 
 677 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
 678   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 679 
 680   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
 681   if (rs_lengths > _rs_lengths_prediction) {
 682     // add 10% to avoid having to recalculate often
 683     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 684     update_young_list_target_length(rs_lengths_prediction);
 685   }
 686 }
 687 
 688 
 689 
 690 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 691                                                bool is_tlab,
 692                                                bool* gc_overhead_limit_was_exceeded) {
 693   guarantee(false, "Not using this policy feature yet.");
 694   return NULL;
 695 }
 696 
 697 // This method controls how a collector handles one or more
 698 // of its generations being fully allocated.
 699 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
 700                                                        bool is_tlab) {
 701   guarantee(false, "Not using this policy feature yet.");
 702   return NULL;
 703 }
 704 
 705 
 706 #ifndef PRODUCT
 707 bool G1CollectorPolicy::verify_young_ages() {
 708   HeapRegion* head = _g1->young_list()->first_region();
 709   return
 710     verify_young_ages(head, _short_lived_surv_rate_group);
 711   // also call verify_young_ages on any additional surv rate groups
 712 }
 713 
 714 bool
 715 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
 716                                      SurvRateGroup *surv_rate_group) {
 717   guarantee( surv_rate_group != NULL, "pre-condition" );
 718 
 719   const char* name = surv_rate_group->name();
 720   bool ret = true;
 721   int prev_age = -1;
 722 
 723   for (HeapRegion* curr = head;
 724        curr != NULL;
 725        curr = curr->get_next_young_region()) {
 726     SurvRateGroup* group = curr->surv_rate_group();
 727     if (group == NULL && !curr->is_survivor()) {
 728       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
 729       ret = false;
 730     }
 731 
 732     if (surv_rate_group == group) {
 733       int age = curr->age_in_surv_rate_group();
 734 
 735       if (age < 0) {
 736         gclog_or_tty->print_cr("## %s: encountered negative age", name);
 737         ret = false;
 738       }
 739 
 740       if (age <= prev_age) {
 741         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
 742                                "(%d, %d)", name, age, prev_age);
 743         ret = false;
 744       }
 745       prev_age = age;
 746     }
 747   }
 748 
 749   return ret;
 750 }
 751 #endif // PRODUCT
 752 
 753 void G1CollectorPolicy::record_full_collection_start() {
 754   _full_collection_start_sec = os::elapsedTime();
 755   // Release the future to-space so that it is available for compaction into.
 756   _g1->set_full_collection();
 757 }
 758 
 759 void G1CollectorPolicy::record_full_collection_end() {
 760   // Consider this like a collection pause for the purposes of allocation
 761   // since last pause.
 762   double end_sec = os::elapsedTime();
 763   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 764   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 765 
 766   _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
 767 
 768   update_recent_gc_times(end_sec, full_gc_time_ms);
 769 
 770   _g1->clear_full_collection();
 771 
 772   // "Nuke" the heuristics that control the young/mixed GC
 773   // transitions and make sure we start with young GCs after the Full GC.
 774   set_gcs_are_young(true);
 775   _last_young_gc = false;
 776   clear_initiate_conc_mark_if_possible();
 777   clear_during_initial_mark_pause();
 778   _in_marking_window = false;
 779   _in_marking_window_im = false;
 780 
 781   _short_lived_surv_rate_group->start_adding_regions();
 782   // also call this on any additional surv rate groups
 783 
 784   record_survivor_regions(0, NULL, NULL);
 785 
 786   _free_regions_at_end_of_collection = _g1->free_regions();
 787   // Reset survivors SurvRateGroup.
 788   _survivor_surv_rate_group->reset();
 789   update_young_list_target_length();
 790   _collectionSetChooser->clear();
 791 }
 792 
 793 void G1CollectorPolicy::record_stop_world_start() {
 794   _stop_world_start = os::elapsedTime();
 795 }
 796 
 797 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
 798                                                       size_t start_used) {
 799   // We only need to do this here as the policy will only be applied
 800   // to the GC we're about to start. so, no point is calculating this
 801   // every time we calculate / recalculate the target young length.
 802   update_survivors_policy();
 803 
 804   assert(_g1->used() == _g1->recalculate_used(),
 805          err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
 806                  _g1->used(), _g1->recalculate_used()));
 807 
 808   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
 809   _trace_gen0_time_data.record_start_collection(s_w_t_ms);
 810   _stop_world_start = 0.0;
 811 
 812   phase_times()->record_cur_collection_start_sec(start_time_sec);
 813   _cur_collection_pause_used_at_start_bytes = start_used;
 814   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
 815   _pending_cards = _g1->pending_card_num();
 816 
 817   _collection_set_bytes_used_before = 0;
 818   _bytes_copied_during_gc = 0;
 819 
 820   YoungList* young_list = _g1->young_list();
 821   _eden_bytes_before_gc = young_list->eden_used_bytes();
 822   _survivor_bytes_before_gc = young_list->survivor_used_bytes();
 823   _capacity_before_gc = _g1->capacity();
 824 
 825   _last_gc_was_young = false;
 826 
 827   // do that for any other surv rate groups
 828   _short_lived_surv_rate_group->stop_adding_regions();
 829   _survivors_age_table.clear();
 830 
 831   assert( verify_young_ages(), "region age verification" );
 832 }
 833 
 834 void G1CollectorPolicy::record_concurrent_mark_init_end(double
 835                                                    mark_init_elapsed_time_ms) {
 836   _during_marking = true;
 837   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
 838   clear_during_initial_mark_pause();
 839   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
 840 }
 841 
 842 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
 843   _mark_remark_start_sec = os::elapsedTime();
 844   _during_marking = false;
 845 }
 846 
 847 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
 848   double end_time_sec = os::elapsedTime();
 849   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 850   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
 851   _cur_mark_stop_world_time_ms += elapsed_time_ms;
 852   _prev_collection_pause_end_ms += elapsed_time_ms;
 853 
 854   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
 855 }
 856 
 857 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
 858   _mark_cleanup_start_sec = os::elapsedTime();
 859 }
 860 
 861 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
 862   _last_young_gc = true;
 863   _in_marking_window = false;
 864 }
 865 
 866 void G1CollectorPolicy::record_concurrent_pause() {
 867   if (_stop_world_start > 0.0) {
 868     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
 869     _trace_gen0_time_data.record_yield_time(yield_ms);
 870   }
 871 }
 872 
 873 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 874   if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
 875     return false;
 876   }
 877 
 878   size_t marking_initiating_used_threshold =
 879     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
 880   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 881   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 882 
 883   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
 884     if (gcs_are_young()) {
 885       ergo_verbose5(ErgoConcCycles,
 886         "request concurrent cycle initiation",
 887         ergo_format_reason("occupancy higher than threshold")
 888         ergo_format_byte("occupancy")
 889         ergo_format_byte("allocation request")
 890         ergo_format_byte_perc("threshold")
 891         ergo_format_str("source"),
 892         cur_used_bytes,
 893         alloc_byte_size,
 894         marking_initiating_used_threshold,
 895         (double) InitiatingHeapOccupancyPercent,
 896         source);
 897       return true;
 898     } else {
 899       ergo_verbose5(ErgoConcCycles,
 900         "do not request concurrent cycle initiation",
 901         ergo_format_reason("still doing mixed collections")
 902         ergo_format_byte("occupancy")
 903         ergo_format_byte("allocation request")
 904         ergo_format_byte_perc("threshold")
 905         ergo_format_str("source"),
 906         cur_used_bytes,
 907         alloc_byte_size,
 908         marking_initiating_used_threshold,
 909         (double) InitiatingHeapOccupancyPercent,
 910         source);
 911     }
 912   }
 913 
 914   return false;
 915 }
 916 
 917 // Anything below that is considered to be zero
 918 #define MIN_TIMER_GRANULARITY 0.0000001
 919 
 920 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms) {
 921   double end_time_sec = os::elapsedTime();
 922   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
 923          "otherwise, the subtraction below does not make sense");
 924   size_t rs_size =
 925             _cur_collection_pause_used_regions_at_start - cset_region_length();
 926   size_t cur_used_bytes = _g1->used();
 927   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 928   bool last_pause_included_initial_mark = false;
 929   bool update_stats = !_g1->evacuation_failed();
 930 
 931 #ifndef PRODUCT
 932   if (G1YoungSurvRateVerbose) {
 933     gclog_or_tty->print_cr("");
 934     _short_lived_surv_rate_group->print();
 935     // do that for any other surv rate groups too
 936   }
 937 #endif // PRODUCT
 938 
 939   last_pause_included_initial_mark = during_initial_mark_pause();
 940   if (last_pause_included_initial_mark) {
 941     record_concurrent_mark_init_end(0.0);
 942   } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
 943     // Note: this might have already been set, if during the last
 944     // pause we decided to start a cycle but at the beginning of
 945     // this pause we decided to postpone it. That's OK.
 946     set_initiate_conc_mark_if_possible();
 947   }
 948 
 949   _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,
 950                           end_time_sec, false);
 951 
 952   size_t freed_bytes =
 953     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
 954   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
 955 
 956   double survival_fraction =
 957     (double)surviving_bytes/
 958     (double)_collection_set_bytes_used_before;
 959 
 960   if (update_stats) {
 961     _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());
 962     // this is where we update the allocation rate of the application
 963     double app_time_ms =
 964       (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);
 965     if (app_time_ms < MIN_TIMER_GRANULARITY) {
 966       // This usually happens due to the timer not having the required
 967       // granularity. Some Linuxes are the usual culprits.
 968       // We'll just set it to something (arbitrarily) small.
 969       app_time_ms = 1.0;
 970     }
 971     // We maintain the invariant that all objects allocated by mutator
 972     // threads will be allocated out of eden regions. So, we can use
 973     // the eden region number allocated since the previous GC to
 974     // calculate the application's allocate rate. The only exception
 975     // to that is humongous objects that are allocated separately. But
 976     // given that humongous object allocations do not really affect
 977     // either the pause's duration nor when the next pause will take
 978     // place we can safely ignore them here.
 979     uint regions_allocated = eden_cset_region_length();
 980     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
 981     _alloc_rate_ms_seq->add(alloc_rate_ms);
 982 
 983     double interval_ms =
 984       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
 985     update_recent_gc_times(end_time_sec, pause_time_ms);
 986     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
 987     if (recent_avg_pause_time_ratio() < 0.0 ||
 988         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
 989 #ifndef PRODUCT
 990       // Dump info to allow post-facto debugging
 991       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
 992       gclog_or_tty->print_cr("-------------------------------------------");
 993       gclog_or_tty->print_cr("Recent GC Times (ms):");
 994       _recent_gc_times_ms->dump();
 995       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
 996       _recent_prev_end_times_for_all_gcs_sec->dump();
 997       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
 998                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
 999       // In debug mode, terminate the JVM if the user wants to debug at this point.
1000       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
1001 #endif  // !PRODUCT
1002       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
1003       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
1004       if (_recent_avg_pause_time_ratio < 0.0) {
1005         _recent_avg_pause_time_ratio = 0.0;
1006       } else {
1007         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
1008         _recent_avg_pause_time_ratio = 1.0;
1009       }
1010     }
1011   }
1012   bool new_in_marking_window = _in_marking_window;
1013   bool new_in_marking_window_im = false;
1014   if (during_initial_mark_pause()) {
1015     new_in_marking_window = true;
1016     new_in_marking_window_im = true;
1017   }
1018 
1019   if (_last_young_gc) {
1020     // This is supposed to to be the "last young GC" before we start
1021     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
1022 
1023     if (!last_pause_included_initial_mark) {
1024       if (next_gc_should_be_mixed("start mixed GCs",
1025                                   "do not start mixed GCs")) {
1026         set_gcs_are_young(false);
1027       }
1028     } else {
1029       ergo_verbose0(ErgoMixedGCs,
1030                     "do not start mixed GCs",
1031                     ergo_format_reason("concurrent cycle is about to start"));
1032     }
1033     _last_young_gc = false;
1034   }
1035 
1036   if (!_last_gc_was_young) {
1037     // This is a mixed GC. Here we decide whether to continue doing
1038     // mixed GCs or not.
1039 
1040     if (!next_gc_should_be_mixed("continue mixed GCs",
1041                                  "do not continue mixed GCs")) {
1042       set_gcs_are_young(true);
1043     }
1044   }
1045 
1046   _short_lived_surv_rate_group->start_adding_regions();
1047   // do that for any other surv rate groupsx
1048 
1049   if (update_stats) {
1050     double cost_per_card_ms = 0.0;
1051     if (_pending_cards > 0) {
1052       cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;
1053       _cost_per_card_ms_seq->add(cost_per_card_ms);
1054     }
1055 
1056     size_t cards_scanned = _g1->cards_scanned();
1057 
1058     double cost_per_entry_ms = 0.0;
1059     if (cards_scanned > 10) {
1060       cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;
1061       if (_last_gc_was_young) {
1062         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
1063       } else {
1064         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
1065       }
1066     }
1067 
1068     if (_max_rs_lengths > 0) {
1069       double cards_per_entry_ratio =
1070         (double) cards_scanned / (double) _max_rs_lengths;
1071       if (_last_gc_was_young) {
1072         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1073       } else {
1074         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
1075       }
1076     }
1077 
1078     // This is defensive. For a while _max_rs_lengths could get
1079     // smaller than _recorded_rs_lengths which was causing
1080     // rs_length_diff to get very large and mess up the RSet length
1081     // predictions. The reason was unsafe concurrent updates to the
1082     // _inc_cset_recorded_rs_lengths field which the code below guards
1083     // against (see CR 7118202). This bug has now been fixed (see CR
1084     // 7119027). However, I'm still worried that
1085     // _inc_cset_recorded_rs_lengths might still end up somewhat
1086     // inaccurate. The concurrent refinement thread calculates an
1087     // RSet's length concurrently with other CR threads updating it
1088     // which might cause it to calculate the length incorrectly (if,
1089     // say, it's in mid-coarsening). So I'll leave in the defensive
1090     // conditional below just in case.
1091     size_t rs_length_diff = 0;
1092     if (_max_rs_lengths > _recorded_rs_lengths) {
1093       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
1094     }
1095     _rs_length_diff_seq->add((double) rs_length_diff);
1096 
1097     size_t copied_bytes = surviving_bytes;
1098     double cost_per_byte_ms = 0.0;
1099     if (copied_bytes > 0) {
1100       cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;
1101       if (_in_marking_window) {
1102         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
1103       } else {
1104         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
1105       }
1106     }
1107 
1108     double all_other_time_ms = pause_time_ms -
1109       (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()
1110       + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());
1111 
1112     double young_other_time_ms = 0.0;
1113     if (young_cset_region_length() > 0) {
1114       young_other_time_ms =
1115         phase_times()->young_cset_choice_time_ms() +
1116         phase_times()->young_free_cset_time_ms();
1117       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
1118                                           (double) young_cset_region_length());
1119     }
1120     double non_young_other_time_ms = 0.0;
1121     if (old_cset_region_length() > 0) {
1122       non_young_other_time_ms =
1123         phase_times()->non_young_cset_choice_time_ms() +
1124         phase_times()->non_young_free_cset_time_ms();
1125 
1126       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
1127                                             (double) old_cset_region_length());
1128     }
1129 
1130     double constant_other_time_ms = all_other_time_ms -
1131       (young_other_time_ms + non_young_other_time_ms);
1132     _constant_other_time_ms_seq->add(constant_other_time_ms);
1133 
1134     double survival_ratio = 0.0;
1135     if (_collection_set_bytes_used_before > 0) {
1136       survival_ratio = (double) _bytes_copied_during_gc /
1137                                    (double) _collection_set_bytes_used_before;
1138     }
1139 
1140     _pending_cards_seq->add((double) _pending_cards);
1141     _rs_lengths_seq->add((double) _max_rs_lengths);
1142   }
1143 
1144   _in_marking_window = new_in_marking_window;
1145   _in_marking_window_im = new_in_marking_window_im;
1146   _free_regions_at_end_of_collection = _g1->free_regions();
1147   update_young_list_target_length();
1148 
1149   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
1150   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
1151   adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),
1152                                phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);
1153 
1154   _collectionSetChooser->verify();
1155 }
1156 
1157 #define EXT_SIZE_FORMAT "%.1f%s"
1158 #define EXT_SIZE_PARAMS(bytes)                                  \
1159   byte_size_in_proper_unit((double)(bytes)),                    \
1160   proper_unit_for_byte_size((bytes))
1161 
1162 void G1CollectorPolicy::print_heap_transition() {
1163   _g1->print_size_transition(gclog_or_tty,
1164     _cur_collection_pause_used_at_start_bytes, _g1->used(), _g1->capacity());
1165 }
1166 
1167 void G1CollectorPolicy::print_detailed_heap_transition() {
1168     YoungList* young_list = _g1->young_list();
1169     size_t eden_bytes = young_list->eden_used_bytes();
1170     size_t survivor_bytes = young_list->survivor_used_bytes();
1171     size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
1172     size_t used = _g1->used();
1173     size_t capacity = _g1->capacity();
1174     size_t eden_capacity =
1175       (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
1176 
1177     gclog_or_tty->print_cr(
1178       "   [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
1179       "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
1180       "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
1181       EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
1182       EXT_SIZE_PARAMS(_eden_bytes_before_gc),
1183       EXT_SIZE_PARAMS(_prev_eden_capacity),
1184       EXT_SIZE_PARAMS(eden_bytes),
1185       EXT_SIZE_PARAMS(eden_capacity),
1186       EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
1187       EXT_SIZE_PARAMS(survivor_bytes),
1188       EXT_SIZE_PARAMS(used_before_gc),
1189       EXT_SIZE_PARAMS(_capacity_before_gc),
1190       EXT_SIZE_PARAMS(used),
1191       EXT_SIZE_PARAMS(capacity));
1192 
1193     _prev_eden_capacity = eden_capacity;
1194 }
1195 
1196 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
1197                                                      double update_rs_processed_buffers,
1198                                                      double goal_ms) {
1199   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1200   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
1201 
1202   if (G1UseAdaptiveConcRefinement) {
1203     const int k_gy = 3, k_gr = 6;
1204     const double inc_k = 1.1, dec_k = 0.9;
1205 
1206     int g = cg1r->green_zone();
1207     if (update_rs_time > goal_ms) {
1208       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
1209     } else {
1210       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
1211         g = (int)MAX2(g * inc_k, g + 1.0);
1212       }
1213     }
1214     // Change the refinement threads params
1215     cg1r->set_green_zone(g);
1216     cg1r->set_yellow_zone(g * k_gy);
1217     cg1r->set_red_zone(g * k_gr);
1218     cg1r->reinitialize_threads();
1219 
1220     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
1221     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
1222                                     cg1r->yellow_zone());
1223     // Change the barrier params
1224     dcqs.set_process_completed_threshold(processing_threshold);
1225     dcqs.set_max_completed_queue(cg1r->red_zone());
1226   }
1227 
1228   int curr_queue_size = dcqs.completed_buffers_num();
1229   if (curr_queue_size >= cg1r->yellow_zone()) {
1230     dcqs.set_completed_queue_padding(curr_queue_size);
1231   } else {
1232     dcqs.set_completed_queue_padding(0);
1233   }
1234   dcqs.notify_if_necessary();
1235 }
1236 
1237 double
1238 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
1239                                                 size_t scanned_cards) {
1240   return
1241     predict_rs_update_time_ms(pending_cards) +
1242     predict_rs_scan_time_ms(scanned_cards) +
1243     predict_constant_other_time_ms();
1244 }
1245 
1246 double
1247 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
1248   size_t rs_length = predict_rs_length_diff();
1249   size_t card_num;
1250   if (gcs_are_young()) {
1251     card_num = predict_young_card_num(rs_length);
1252   } else {
1253     card_num = predict_non_young_card_num(rs_length);
1254   }
1255   return predict_base_elapsed_time_ms(pending_cards, card_num);
1256 }
1257 
1258 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
1259   size_t bytes_to_copy;
1260   if (hr->is_marked())
1261     bytes_to_copy = hr->max_live_bytes();
1262   else {
1263     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
1264     int age = hr->age_in_surv_rate_group();
1265     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
1266     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
1267   }
1268   return bytes_to_copy;
1269 }
1270 
1271 double
1272 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
1273                                                   bool for_young_gc) {
1274   size_t rs_length = hr->rem_set()->occupied();
1275   size_t card_num;
1276 
1277   // Predicting the number of cards is based on which type of GC
1278   // we're predicting for.
1279   if (for_young_gc) {
1280     card_num = predict_young_card_num(rs_length);
1281   } else {
1282     card_num = predict_non_young_card_num(rs_length);
1283   }
1284   size_t bytes_to_copy = predict_bytes_to_copy(hr);
1285 
1286   double region_elapsed_time_ms =
1287     predict_rs_scan_time_ms(card_num) +
1288     predict_object_copy_time_ms(bytes_to_copy);
1289 
1290   // The prediction of the "other" time for this region is based
1291   // upon the region type and NOT the GC type.
1292   if (hr->is_young()) {
1293     region_elapsed_time_ms += predict_young_other_time_ms(1);
1294   } else {
1295     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
1296   }
1297   return region_elapsed_time_ms;
1298 }
1299 
1300 void
1301 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
1302                                             uint survivor_cset_region_length) {
1303   _eden_cset_region_length     = eden_cset_region_length;
1304   _survivor_cset_region_length = survivor_cset_region_length;
1305   _old_cset_region_length      = 0;
1306 }
1307 
1308 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
1309   _recorded_rs_lengths = rs_lengths;
1310 }
1311 
1312 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
1313                                                double elapsed_ms) {
1314   _recent_gc_times_ms->add(elapsed_ms);
1315   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
1316   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
1317 }
1318 
1319 size_t G1CollectorPolicy::expansion_amount() {
1320   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
1321   double threshold = _gc_overhead_perc;
1322   if (recent_gc_overhead > threshold) {
1323     // We will double the existing space, or take
1324     // G1ExpandByPercentOfAvailable % of the available expansion
1325     // space, whichever is smaller, bounded below by a minimum
1326     // expansion (unless that's all that's left.)
1327     const size_t min_expand_bytes = 1*M;
1328     size_t reserved_bytes = _g1->max_capacity();
1329     size_t committed_bytes = _g1->capacity();
1330     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
1331     size_t expand_bytes;
1332     size_t expand_bytes_via_pct =
1333       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
1334     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
1335     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
1336     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
1337 
1338     ergo_verbose5(ErgoHeapSizing,
1339                   "attempt heap expansion",
1340                   ergo_format_reason("recent GC overhead higher than "
1341                                      "threshold after GC")
1342                   ergo_format_perc("recent GC overhead")
1343                   ergo_format_perc("threshold")
1344                   ergo_format_byte("uncommitted")
1345                   ergo_format_byte_perc("calculated expansion amount"),
1346                   recent_gc_overhead, threshold,
1347                   uncommitted_bytes,
1348                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
1349 
1350     return expand_bytes;
1351   } else {
1352     return 0;
1353   }
1354 }
1355 
1356 void G1CollectorPolicy::print_tracing_info() const {
1357   _trace_gen0_time_data.print();
1358   _trace_gen1_time_data.print();
1359 }
1360 
1361 void G1CollectorPolicy::print_yg_surv_rate_info() const {
1362 #ifndef PRODUCT
1363   _short_lived_surv_rate_group->print_surv_rate_summary();
1364   // add this call for any other surv rate groups
1365 #endif // PRODUCT
1366 }
1367 
1368 #ifndef PRODUCT
1369 // for debugging, bit of a hack...
1370 static char*
1371 region_num_to_mbs(int length) {
1372   static char buffer[64];
1373   double bytes = (double) (length * HeapRegion::GrainBytes);
1374   double mbs = bytes / (double) (1024 * 1024);
1375   sprintf(buffer, "%7.2lfMB", mbs);
1376   return buffer;
1377 }
1378 #endif // PRODUCT
1379 
1380 uint G1CollectorPolicy::max_regions(int purpose) {
1381   switch (purpose) {
1382     case GCAllocForSurvived:
1383       return _max_survivor_regions;
1384     case GCAllocForTenured:
1385       return REGIONS_UNLIMITED;
1386     default:
1387       ShouldNotReachHere();
1388       return REGIONS_UNLIMITED;
1389   };
1390 }
1391 
1392 void G1CollectorPolicy::update_max_gc_locker_expansion() {
1393   uint expansion_region_num = 0;
1394   if (GCLockerEdenExpansionPercent > 0) {
1395     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
1396     double expansion_region_num_d = perc * (double) _young_list_target_length;
1397     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
1398     // less than 1.0) we'll get 1.
1399     expansion_region_num = (uint) ceil(expansion_region_num_d);
1400   } else {
1401     assert(expansion_region_num == 0, "sanity");
1402   }
1403   _young_list_max_length = _young_list_target_length + expansion_region_num;
1404   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
1405 }
1406 
1407 // Calculates survivor space parameters.
1408 void G1CollectorPolicy::update_survivors_policy() {
1409   double max_survivor_regions_d =
1410                  (double) _young_list_target_length / (double) SurvivorRatio;
1411   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
1412   // smaller than 1.0) we'll get 1.
1413   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
1414 
1415   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
1416         HeapRegion::GrainWords * _max_survivor_regions);
1417 }
1418 
1419 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
1420                                                      GCCause::Cause gc_cause) {
1421   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1422   if (!during_cycle) {
1423     ergo_verbose1(ErgoConcCycles,
1424                   "request concurrent cycle initiation",
1425                   ergo_format_reason("requested by GC cause")
1426                   ergo_format_str("GC cause"),
1427                   GCCause::to_string(gc_cause));
1428     set_initiate_conc_mark_if_possible();
1429     return true;
1430   } else {
1431     ergo_verbose1(ErgoConcCycles,
1432                   "do not request concurrent cycle initiation",
1433                   ergo_format_reason("concurrent cycle already in progress")
1434                   ergo_format_str("GC cause"),
1435                   GCCause::to_string(gc_cause));
1436     return false;
1437   }
1438 }
1439 
1440 void
1441 G1CollectorPolicy::decide_on_conc_mark_initiation() {
1442   // We are about to decide on whether this pause will be an
1443   // initial-mark pause.
1444 
1445   // First, during_initial_mark_pause() should not be already set. We
1446   // will set it here if we have to. However, it should be cleared by
1447   // the end of the pause (it's only set for the duration of an
1448   // initial-mark pause).
1449   assert(!during_initial_mark_pause(), "pre-condition");
1450 
1451   if (initiate_conc_mark_if_possible()) {
1452     // We had noticed on a previous pause that the heap occupancy has
1453     // gone over the initiating threshold and we should start a
1454     // concurrent marking cycle. So we might initiate one.
1455 
1456     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
1457     if (!during_cycle) {
1458       // The concurrent marking thread is not "during a cycle", i.e.,
1459       // it has completed the last one. So we can go ahead and
1460       // initiate a new cycle.
1461 
1462       set_during_initial_mark_pause();
1463       // We do not allow mixed GCs during marking.
1464       if (!gcs_are_young()) {
1465         set_gcs_are_young(true);
1466         ergo_verbose0(ErgoMixedGCs,
1467                       "end mixed GCs",
1468                       ergo_format_reason("concurrent cycle is about to start"));
1469       }
1470 
1471       // And we can now clear initiate_conc_mark_if_possible() as
1472       // we've already acted on it.
1473       clear_initiate_conc_mark_if_possible();
1474 
1475       ergo_verbose0(ErgoConcCycles,
1476                   "initiate concurrent cycle",
1477                   ergo_format_reason("concurrent cycle initiation requested"));
1478     } else {
1479       // The concurrent marking thread is still finishing up the
1480       // previous cycle. If we start one right now the two cycles
1481       // overlap. In particular, the concurrent marking thread might
1482       // be in the process of clearing the next marking bitmap (which
1483       // we will use for the next cycle if we start one). Starting a
1484       // cycle now will be bad given that parts of the marking
1485       // information might get cleared by the marking thread. And we
1486       // cannot wait for the marking thread to finish the cycle as it
1487       // periodically yields while clearing the next marking bitmap
1488       // and, if it's in a yield point, it's waiting for us to
1489       // finish. So, at this point we will not start a cycle and we'll
1490       // let the concurrent marking thread complete the last one.
1491       ergo_verbose0(ErgoConcCycles,
1492                     "do not initiate concurrent cycle",
1493                     ergo_format_reason("concurrent cycle already in progress"));
1494     }
1495   }
1496 }
1497 
1498 class KnownGarbageClosure: public HeapRegionClosure {
1499   G1CollectedHeap* _g1h;
1500   CollectionSetChooser* _hrSorted;
1501 
1502 public:
1503   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
1504     _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
1505 
1506   bool doHeapRegion(HeapRegion* r) {
1507     // We only include humongous regions in collection
1508     // sets when concurrent mark shows that their contained object is
1509     // unreachable.
1510 
1511     // Do we have any marking information for this region?
1512     if (r->is_marked()) {
1513       // We will skip any region that's currently used as an old GC
1514       // alloc region (we should not consider those for collection
1515       // before we fill them up).
1516       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1517         _hrSorted->add_region(r);
1518       }
1519     }
1520     return false;
1521   }
1522 };
1523 
1524 class ParKnownGarbageHRClosure: public HeapRegionClosure {
1525   G1CollectedHeap* _g1h;
1526   CSetChooserParUpdater _cset_updater;
1527 
1528 public:
1529   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
1530                            uint chunk_size) :
1531     _g1h(G1CollectedHeap::heap()),
1532     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
1533 
1534   bool doHeapRegion(HeapRegion* r) {
1535     // Do we have any marking information for this region?
1536     if (r->is_marked()) {
1537       // We will skip any region that's currently used as an old GC
1538       // alloc region (we should not consider those for collection
1539       // before we fill them up).
1540       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
1541         _cset_updater.add_region(r);
1542       }
1543     }
1544     return false;
1545   }
1546 };
1547 
1548 class ParKnownGarbageTask: public AbstractGangTask {
1549   CollectionSetChooser* _hrSorted;
1550   uint _chunk_size;
1551   G1CollectedHeap* _g1;
1552 public:
1553   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
1554     AbstractGangTask("ParKnownGarbageTask"),
1555     _hrSorted(hrSorted), _chunk_size(chunk_size),
1556     _g1(G1CollectedHeap::heap()) { }
1557 
1558   void work(uint worker_id) {
1559     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
1560 
1561     // Back to zero for the claim value.
1562     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
1563                                          _g1->workers()->active_workers(),
1564                                          HeapRegion::InitialClaimValue);
1565   }
1566 };
1567 
1568 void
1569 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
1570   _collectionSetChooser->clear();
1571 
1572   uint region_num = _g1->n_regions();
1573   if (G1CollectedHeap::use_parallel_gc_threads()) {
1574     const uint OverpartitionFactor = 4;
1575     uint WorkUnit;
1576     // The use of MinChunkSize = 8 in the original code
1577     // causes some assertion failures when the total number of
1578     // region is less than 8.  The code here tries to fix that.
1579     // Should the original code also be fixed?
1580     if (no_of_gc_threads > 0) {
1581       const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
1582       WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
1583                       MinWorkUnit);
1584     } else {
1585       assert(no_of_gc_threads > 0,
1586         "The active gc workers should be greater than 0");
1587       // In a product build do something reasonable to avoid a crash.
1588       const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
1589       WorkUnit =
1590         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
1591              MinWorkUnit);
1592     }
1593     _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
1594                                                            WorkUnit);
1595     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
1596                                             (int) WorkUnit);
1597     _g1->workers()->run_task(&parKnownGarbageTask);
1598 
1599     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1600            "sanity check");
1601   } else {
1602     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
1603     _g1->heap_region_iterate(&knownGarbagecl);
1604   }
1605 
1606   _collectionSetChooser->sort_regions();
1607 
1608   double end_sec = os::elapsedTime();
1609   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1610   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
1611   _cur_mark_stop_world_time_ms += elapsed_time_ms;
1612   _prev_collection_pause_end_ms += elapsed_time_ms;
1613   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
1614 }
1615 
1616 // Add the heap region at the head of the non-incremental collection set
1617 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
1618   assert(_inc_cset_build_state == Active, "Precondition");
1619   assert(!hr->is_young(), "non-incremental add of young region");
1620 
1621   assert(!hr->in_collection_set(), "should not already be in the CSet");
1622   hr->set_in_collection_set(true);
1623   hr->set_next_in_collection_set(_collection_set);
1624   _collection_set = hr;
1625   _collection_set_bytes_used_before += hr->used();
1626   _g1->register_region_with_in_cset_fast_test(hr);
1627   size_t rs_length = hr->rem_set()->occupied();
1628   _recorded_rs_lengths += rs_length;
1629   _old_cset_region_length += 1;
1630 }
1631 
1632 // Initialize the per-collection-set information
1633 void G1CollectorPolicy::start_incremental_cset_building() {
1634   assert(_inc_cset_build_state == Inactive, "Precondition");
1635 
1636   _inc_cset_head = NULL;
1637   _inc_cset_tail = NULL;
1638   _inc_cset_bytes_used_before = 0;
1639 
1640   _inc_cset_max_finger = 0;
1641   _inc_cset_recorded_rs_lengths = 0;
1642   _inc_cset_recorded_rs_lengths_diffs = 0;
1643   _inc_cset_predicted_elapsed_time_ms = 0.0;
1644   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1645   _inc_cset_build_state = Active;
1646 }
1647 
1648 void G1CollectorPolicy::finalize_incremental_cset_building() {
1649   assert(_inc_cset_build_state == Active, "Precondition");
1650   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1651 
1652   // The two "main" fields, _inc_cset_recorded_rs_lengths and
1653   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
1654   // that adds a new region to the CSet. Further updates by the
1655   // concurrent refinement thread that samples the young RSet lengths
1656   // are accumulated in the *_diffs fields. Here we add the diffs to
1657   // the "main" fields.
1658 
1659   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
1660     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
1661   } else {
1662     // This is defensive. The diff should in theory be always positive
1663     // as RSets can only grow between GCs. However, given that we
1664     // sample their size concurrently with other threads updating them
1665     // it's possible that we might get the wrong size back, which
1666     // could make the calculations somewhat inaccurate.
1667     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
1668     if (_inc_cset_recorded_rs_lengths >= diffs) {
1669       _inc_cset_recorded_rs_lengths -= diffs;
1670     } else {
1671       _inc_cset_recorded_rs_lengths = 0;
1672     }
1673   }
1674   _inc_cset_predicted_elapsed_time_ms +=
1675                                      _inc_cset_predicted_elapsed_time_ms_diffs;
1676 
1677   _inc_cset_recorded_rs_lengths_diffs = 0;
1678   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
1679 }
1680 
1681 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
1682   // This routine is used when:
1683   // * adding survivor regions to the incremental cset at the end of an
1684   //   evacuation pause,
1685   // * adding the current allocation region to the incremental cset
1686   //   when it is retired, and
1687   // * updating existing policy information for a region in the
1688   //   incremental cset via young list RSet sampling.
1689   // Therefore this routine may be called at a safepoint by the
1690   // VM thread, or in-between safepoints by mutator threads (when
1691   // retiring the current allocation region) or a concurrent
1692   // refine thread (RSet sampling).
1693 
1694   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1695   size_t used_bytes = hr->used();
1696   _inc_cset_recorded_rs_lengths += rs_length;
1697   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
1698   _inc_cset_bytes_used_before += used_bytes;
1699 
1700   // Cache the values we have added to the aggregated informtion
1701   // in the heap region in case we have to remove this region from
1702   // the incremental collection set, or it is updated by the
1703   // rset sampling code
1704   hr->set_recorded_rs_length(rs_length);
1705   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
1706 }
1707 
1708 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
1709                                                      size_t new_rs_length) {
1710   // Update the CSet information that is dependent on the new RS length
1711   assert(hr->is_young(), "Precondition");
1712   assert(!SafepointSynchronize::is_at_safepoint(),
1713                                                "should not be at a safepoint");
1714 
1715   // We could have updated _inc_cset_recorded_rs_lengths and
1716   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
1717   // that atomically, as this code is executed by a concurrent
1718   // refinement thread, potentially concurrently with a mutator thread
1719   // allocating a new region and also updating the same fields. To
1720   // avoid the atomic operations we accumulate these updates on two
1721   // separate fields (*_diffs) and we'll just add them to the "main"
1722   // fields at the start of a GC.
1723 
1724   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
1725   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
1726   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
1727 
1728   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
1729   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1730   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
1731   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
1732 
1733   hr->set_recorded_rs_length(new_rs_length);
1734   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
1735 }
1736 
1737 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
1738   assert(hr->is_young(), "invariant");
1739   assert(hr->young_index_in_cset() > -1, "should have already been set");
1740   assert(_inc_cset_build_state == Active, "Precondition");
1741 
1742   // We need to clear and set the cached recorded/cached collection set
1743   // information in the heap region here (before the region gets added
1744   // to the collection set). An individual heap region's cached values
1745   // are calculated, aggregated with the policy collection set info,
1746   // and cached in the heap region here (initially) and (subsequently)
1747   // by the Young List sampling code.
1748 
1749   size_t rs_length = hr->rem_set()->occupied();
1750   add_to_incremental_cset_info(hr, rs_length);
1751 
1752   HeapWord* hr_end = hr->end();
1753   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
1754 
1755   assert(!hr->in_collection_set(), "invariant");
1756   hr->set_in_collection_set(true);
1757   assert( hr->next_in_collection_set() == NULL, "invariant");
1758 
1759   _g1->register_region_with_in_cset_fast_test(hr);
1760 }
1761 
1762 // Add the region at the RHS of the incremental cset
1763 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
1764   // We should only ever be appending survivors at the end of a pause
1765   assert( hr->is_survivor(), "Logic");
1766 
1767   // Do the 'common' stuff
1768   add_region_to_incremental_cset_common(hr);
1769 
1770   // Now add the region at the right hand side
1771   if (_inc_cset_tail == NULL) {
1772     assert(_inc_cset_head == NULL, "invariant");
1773     _inc_cset_head = hr;
1774   } else {
1775     _inc_cset_tail->set_next_in_collection_set(hr);
1776   }
1777   _inc_cset_tail = hr;
1778 }
1779 
1780 // Add the region to the LHS of the incremental cset
1781 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
1782   // Survivors should be added to the RHS at the end of a pause
1783   assert(!hr->is_survivor(), "Logic");
1784 
1785   // Do the 'common' stuff
1786   add_region_to_incremental_cset_common(hr);
1787 
1788   // Add the region at the left hand side
1789   hr->set_next_in_collection_set(_inc_cset_head);
1790   if (_inc_cset_head == NULL) {
1791     assert(_inc_cset_tail == NULL, "Invariant");
1792     _inc_cset_tail = hr;
1793   }
1794   _inc_cset_head = hr;
1795 }
1796 
1797 #ifndef PRODUCT
1798 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
1799   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
1800 
1801   st->print_cr("\nCollection_set:");
1802   HeapRegion* csr = list_head;
1803   while (csr != NULL) {
1804     HeapRegion* next = csr->next_in_collection_set();
1805     assert(csr->in_collection_set(), "bad CS");
1806     st->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
1807                  HR_FORMAT_PARAMS(csr),
1808                  csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
1809                  csr->age_in_surv_rate_group_cond());
1810     csr = next;
1811   }
1812 }
1813 #endif // !PRODUCT
1814 
1815 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1816                                                 const char* false_action_str) {
1817   CollectionSetChooser* cset_chooser = _collectionSetChooser;
1818   if (cset_chooser->is_empty()) {
1819     ergo_verbose0(ErgoMixedGCs,
1820                   false_action_str,
1821                   ergo_format_reason("candidate old regions not available"));
1822     return false;
1823   }
1824   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1825   size_t capacity_bytes = _g1->capacity();
1826   double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1827   double threshold = (double) G1HeapWastePercent;
1828   if (perc < threshold) {
1829     ergo_verbose4(ErgoMixedGCs,
1830               false_action_str,
1831               ergo_format_reason("reclaimable percentage lower than threshold")
1832               ergo_format_region("candidate old regions")
1833               ergo_format_byte_perc("reclaimable")
1834               ergo_format_perc("threshold"),
1835               cset_chooser->remaining_regions(),
1836               reclaimable_bytes, perc, threshold);
1837     return false;
1838   }
1839 
1840   ergo_verbose4(ErgoMixedGCs,
1841                 true_action_str,
1842                 ergo_format_reason("candidate old regions available")
1843                 ergo_format_region("candidate old regions")
1844                 ergo_format_byte_perc("reclaimable")
1845                 ergo_format_perc("threshold"),
1846                 cset_chooser->remaining_regions(),
1847                 reclaimable_bytes, perc, threshold);
1848   return true;
1849 }
1850 
1851 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
1852   double young_start_time_sec = os::elapsedTime();
1853 
1854   YoungList* young_list = _g1->young_list();
1855   finalize_incremental_cset_building();
1856 
1857   guarantee(target_pause_time_ms > 0.0,
1858             err_msg("target_pause_time_ms = %1.6lf should be positive",
1859                     target_pause_time_ms));
1860   guarantee(_collection_set == NULL, "Precondition");
1861 
1862   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1863   double predicted_pause_time_ms = base_time_ms;
1864   double time_remaining_ms = target_pause_time_ms - base_time_ms;
1865 
1866   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1867                 "start choosing CSet",
1868                 ergo_format_size("_pending_cards")
1869                 ergo_format_ms("predicted base time")
1870                 ergo_format_ms("remaining time")
1871                 ergo_format_ms("target pause time"),
1872                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
1873 
1874   _last_gc_was_young = gcs_are_young() ? true : false;
1875 
1876   if (_last_gc_was_young) {
1877     _trace_gen0_time_data.increment_young_collection_count();
1878   } else {
1879     _trace_gen0_time_data.increment_mixed_collection_count();
1880   }
1881 
1882   // The young list is laid with the survivor regions from the previous
1883   // pause are appended to the RHS of the young list, i.e.
1884   //   [Newly Young Regions ++ Survivors from last pause].
1885 
1886   uint survivor_region_length = young_list->survivor_length();
1887   uint eden_region_length = young_list->length() - survivor_region_length;
1888   init_cset_region_lengths(eden_region_length, survivor_region_length);
1889 
1890   HeapRegion* hr = young_list->first_survivor_region();
1891   while (hr != NULL) {
1892     assert(hr->is_survivor(), "badly formed young list");
1893     hr->set_young();
1894     hr = hr->get_next_young_region();
1895   }
1896 
1897   // Clear the fields that point to the survivor list - they are all young now.
1898   young_list->clear_survivors();
1899 
1900   _collection_set = _inc_cset_head;
1901   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1902   time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
1903   predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1904 
1905   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1906                 "add young regions to CSet",
1907                 ergo_format_region("eden")
1908                 ergo_format_region("survivors")
1909                 ergo_format_ms("predicted young region time"),
1910                 eden_region_length, survivor_region_length,
1911                 _inc_cset_predicted_elapsed_time_ms);
1912 
1913   // The number of recorded young regions is the incremental
1914   // collection set's current size
1915   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
1916 
1917   double young_end_time_sec = os::elapsedTime();
1918   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
1919 
1920   // Set the start of the non-young choice time.
1921   double non_young_start_time_sec = young_end_time_sec;
1922 
1923   if (!gcs_are_young()) {
1924     CollectionSetChooser* cset_chooser = _collectionSetChooser;
1925     cset_chooser->verify();
1926     const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
1927     const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
1928 
1929     uint expensive_region_num = 0;
1930     bool check_time_remaining = adaptive_young_list_length();
1931 
1932     HeapRegion* hr = cset_chooser->peek();
1933     while (hr != NULL) {
1934       if (old_cset_region_length() >= max_old_cset_length) {
1935         // Added maximum number of old regions to the CSet.
1936         ergo_verbose2(ErgoCSetConstruction,
1937                       "finish adding old regions to CSet",
1938                       ergo_format_reason("old CSet region num reached max")
1939                       ergo_format_region("old")
1940                       ergo_format_region("max"),
1941                       old_cset_region_length(), max_old_cset_length);
1942         break;
1943       }
1944 
1945       double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1946       if (check_time_remaining) {
1947         if (predicted_time_ms > time_remaining_ms) {
1948           // Too expensive for the current CSet.
1949 
1950           if (old_cset_region_length() >= min_old_cset_length) {
1951             // We have added the minimum number of old regions to the CSet,
1952             // we are done with this CSet.
1953             ergo_verbose4(ErgoCSetConstruction,
1954                           "finish adding old regions to CSet",
1955                           ergo_format_reason("predicted time is too high")
1956                           ergo_format_ms("predicted time")
1957                           ergo_format_ms("remaining time")
1958                           ergo_format_region("old")
1959                           ergo_format_region("min"),
1960                           predicted_time_ms, time_remaining_ms,
1961                           old_cset_region_length(), min_old_cset_length);
1962             break;
1963           }
1964 
1965           // We'll add it anyway given that we haven't reached the
1966           // minimum number of old regions.
1967           expensive_region_num += 1;
1968         }
1969       } else {
1970         if (old_cset_region_length() >= min_old_cset_length) {
1971           // In the non-auto-tuning case, we'll finish adding regions
1972           // to the CSet if we reach the minimum.
1973           ergo_verbose2(ErgoCSetConstruction,
1974                         "finish adding old regions to CSet",
1975                         ergo_format_reason("old CSet region num reached min")
1976                         ergo_format_region("old")
1977                         ergo_format_region("min"),
1978                         old_cset_region_length(), min_old_cset_length);
1979           break;
1980         }
1981       }
1982 
1983       // We will add this region to the CSet.
1984       time_remaining_ms -= predicted_time_ms;
1985       predicted_pause_time_ms += predicted_time_ms;
1986       cset_chooser->remove_and_move_to_next(hr);
1987       _g1->old_set_remove(hr);
1988       add_old_region_to_cset(hr);
1989 
1990       hr = cset_chooser->peek();
1991     }
1992     if (hr == NULL) {
1993       ergo_verbose0(ErgoCSetConstruction,
1994                     "finish adding old regions to CSet",
1995                     ergo_format_reason("candidate old regions not available"));
1996     }
1997 
1998     if (expensive_region_num > 0) {
1999       // We print the information once here at the end, predicated on
2000       // whether we added any apparently expensive regions or not, to
2001       // avoid generating output per region.
2002       ergo_verbose4(ErgoCSetConstruction,
2003                     "added expensive regions to CSet",
2004                     ergo_format_reason("old CSet region num not reached min")
2005                     ergo_format_region("old")
2006                     ergo_format_region("expensive")
2007                     ergo_format_region("min")
2008                     ergo_format_ms("remaining time"),
2009                     old_cset_region_length(),
2010                     expensive_region_num,
2011                     min_old_cset_length,
2012                     time_remaining_ms);
2013     }
2014 
2015     cset_chooser->verify();
2016   }
2017 
2018   stop_incremental_cset_building();
2019 
2020   ergo_verbose5(ErgoCSetConstruction,
2021                 "finish choosing CSet",
2022                 ergo_format_region("eden")
2023                 ergo_format_region("survivors")
2024                 ergo_format_region("old")
2025                 ergo_format_ms("predicted pause time")
2026                 ergo_format_ms("target pause time"),
2027                 eden_region_length, survivor_region_length,
2028                 old_cset_region_length(),
2029                 predicted_pause_time_ms, target_pause_time_ms);
2030 
2031   double non_young_end_time_sec = os::elapsedTime();
2032   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
2033 }
2034 
2035 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
2036   if(TraceGen0Time) {
2037     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
2038   }
2039 }
2040 
2041 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
2042   if(TraceGen0Time) {
2043     _all_yield_times_ms.add(yield_time_ms);
2044   }
2045 }
2046 
2047 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {
2048   if(TraceGen0Time) {
2049     _total.add(pause_time_ms);
2050     _other.add(pause_time_ms - phase_times->accounted_time_ms());
2051     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());
2052     _parallel.add(phase_times->cur_collection_par_time_ms());
2053     _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());
2054     _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());
2055     _update_rs.add(phase_times->average_last_update_rs_time());
2056     _scan_rs.add(phase_times->average_last_scan_rs_time());
2057     _obj_copy.add(phase_times->average_last_obj_copy_time());
2058     _termination.add(phase_times->average_last_termination_time());
2059 
2060     double parallel_known_time = phase_times->average_last_ext_root_scan_time() +
2061       phase_times->average_last_satb_filtering_times_ms() +
2062       phase_times->average_last_update_rs_time() +
2063       phase_times->average_last_scan_rs_time() +
2064       phase_times->average_last_obj_copy_time() +
2065       + phase_times->average_last_termination_time();
2066 
2067     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;
2068     _parallel_other.add(parallel_other_time);
2069     _clear_ct.add(phase_times->cur_clear_ct_time_ms());
2070   }
2071 }
2072 
2073 void TraceGen0TimeData::increment_young_collection_count() {
2074   if(TraceGen0Time) {
2075     ++_young_pause_num;
2076   }
2077 }
2078 
2079 void TraceGen0TimeData::increment_mixed_collection_count() {
2080   if(TraceGen0Time) {
2081     ++_mixed_pause_num;
2082   }
2083 }
2084 
2085 void TraceGen0TimeData::print_summary(const char* str,
2086                                       const NumberSeq* seq) const {
2087   double sum = seq->sum();
2088   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",
2089                 str, sum / 1000.0, seq->avg());
2090 }
2091 
2092 void TraceGen0TimeData::print_summary_sd(const char* str,
2093                                          const NumberSeq* seq) const {
2094   print_summary(str, seq);
2095   gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
2096                 "(num", seq->num(), seq->sd(), seq->maximum());
2097 }
2098 
2099 void TraceGen0TimeData::print() const {
2100   if (!TraceGen0Time) {
2101     return;
2102   }
2103 
2104   gclog_or_tty->print_cr("ALL PAUSES");
2105   print_summary_sd("   Total", &_total);
2106   gclog_or_tty->print_cr("");
2107   gclog_or_tty->print_cr("");
2108   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
2109   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
2110   gclog_or_tty->print_cr("");
2111 
2112   gclog_or_tty->print_cr("EVACUATION PAUSES");
2113 
2114   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
2115     gclog_or_tty->print_cr("none");
2116   } else {
2117     print_summary_sd("   Evacuation Pauses", &_total);
2118     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);
2119     print_summary("      Parallel Time", &_parallel);
2120     print_summary("         Ext Root Scanning", &_ext_root_scan);
2121     print_summary("         SATB Filtering", &_satb_filtering);
2122     print_summary("         Update RS", &_update_rs);
2123     print_summary("         Scan RS", &_scan_rs);
2124     print_summary("         Object Copy", &_obj_copy);
2125     print_summary("         Termination", &_termination);
2126     print_summary("         Parallel Other", &_parallel_other);
2127     print_summary("      Clear CT", &_clear_ct);
2128     print_summary("      Other", &_other);
2129   }
2130   gclog_or_tty->print_cr("");
2131 
2132   gclog_or_tty->print_cr("MISC");
2133   print_summary_sd("   Stop World", &_all_stop_world_times_ms);
2134   print_summary_sd("   Yields", &_all_yield_times_ms);
2135 }
2136 
2137 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
2138   if (TraceGen1Time) {
2139     _all_full_gc_times.add(full_gc_time_ms);
2140   }
2141 }
2142 
2143 void TraceGen1TimeData::print() const {
2144   if (!TraceGen1Time) {
2145     return;
2146   }
2147 
2148   if (_all_full_gc_times.num() > 0) {
2149     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
2150       _all_full_gc_times.num(),
2151       _all_full_gc_times.sum() / 1000.0);
2152     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
2153     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
2154       _all_full_gc_times.sd(),
2155       _all_full_gc_times.maximum());
2156   }
2157 }