rev 47675 : [mq]: 8149127-rename-concurrentrefine-a
rev 47677 : [mq]: 8149127-rename-concurrentrefine-b-stefanj-review

   1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"

  26 #include "gc/g1/concurrentMarkThread.inline.hpp"
  27 #include "gc/g1/g1Analytics.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1CollectionSet.hpp"
  30 #include "gc/g1/g1ConcurrentMark.hpp"
  31 #include "gc/g1/g1ConcurrentRefine.hpp"
  32 #include "gc/g1/g1DefaultPolicy.hpp"
  33 #include "gc/g1/g1HotCardCache.hpp"
  34 #include "gc/g1/g1IHOPControl.hpp"
  35 #include "gc/g1/g1GCPhaseTimes.hpp"
  36 #include "gc/g1/g1Policy.hpp"
  37 #include "gc/g1/g1SurvivorRegions.hpp"
  38 #include "gc/g1/g1YoungGenSizer.hpp"
  39 #include "gc/g1/heapRegion.inline.hpp"
  40 #include "gc/g1/heapRegionRemSet.hpp"
  41 #include "gc/shared/gcPolicyCounters.hpp"
  42 #include "logging/logStream.hpp"
  43 #include "runtime/arguments.hpp"
  44 #include "runtime/java.hpp"
  45 #include "runtime/mutexLocker.hpp"
  46 #include "utilities/debug.hpp"
  47 #include "utilities/growableArray.hpp"
  48 #include "utilities/pair.hpp"
  49 
  50 G1DefaultPolicy::G1DefaultPolicy(STWGCTimer* gc_timer) :
  51   _predictor(G1ConfidencePercent / 100.0),
  52   _analytics(new G1Analytics(&_predictor)),
  53   _mmu_tracker(new G1MMUTrackerQueue(GCPauseIntervalMillis / 1000.0, MaxGCPauseMillis / 1000.0)),
  54   _ihop_control(create_ihop_control(&_predictor)),
  55   _policy_counters(new GCPolicyCounters("GarbageFirst", 1, 3)),
  56   _young_list_fixed_length(0),
  57   _short_lived_surv_rate_group(new SurvRateGroup()),
  58   _survivor_surv_rate_group(new SurvRateGroup()),
  59   _reserve_factor((double) G1ReservePercent / 100.0),
  60   _reserve_regions(0),
  61   _rs_lengths_prediction(0),
  62   _bytes_allocated_in_old_since_last_gc(0),
  63   _initial_mark_to_mixed(),
  64   _collection_set(NULL),
  65   _g1(NULL),
  66   _phase_times(new G1GCPhaseTimes(gc_timer, ParallelGCThreads)),
  67   _tenuring_threshold(MaxTenuringThreshold),
  68   _max_survivor_regions(0),
  69   _survivors_age_table(true),
  70   _collection_pause_end_millis(os::javaTimeNanos() / NANOSECS_PER_MILLISEC) { }
  71 
  72 G1DefaultPolicy::~G1DefaultPolicy() {
  73   delete _ihop_control;
  74 }
  75 
  76 G1CollectorState* G1DefaultPolicy::collector_state() const { return _g1->collector_state(); }
  77 
  78 void G1DefaultPolicy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) {
  79   _g1 = g1h;
  80   _collection_set = collection_set;
  81 
  82   assert(Heap_lock->owned_by_self(), "Locking discipline.");
  83 
  84   if (!adaptive_young_list_length()) {
  85     _young_list_fixed_length = _young_gen_sizer.min_desired_young_length();
  86   }
  87   _young_gen_sizer.adjust_max_new_size(_g1->max_regions());
  88 
  89   _free_regions_at_end_of_collection = _g1->num_free_regions();
  90 
  91   update_young_list_max_and_target_length();
  92   // We may immediately start allocating regions and placing them on the
  93   // collection set list. Initialize the per-collection set info
  94   _collection_set->start_incremental_building();
  95 }
  96 
  97 void G1DefaultPolicy::note_gc_start() {
  98   phase_times()->note_gc_start();
  99 }
 100 
 101 class G1YoungLengthPredictor VALUE_OBJ_CLASS_SPEC {
 102   const bool _during_cm;
 103   const double _base_time_ms;
 104   const double _base_free_regions;
 105   const double _target_pause_time_ms;
 106   const G1DefaultPolicy* const _policy;
 107 
 108  public:
 109   G1YoungLengthPredictor(bool during_cm,
 110                          double base_time_ms,
 111                          double base_free_regions,
 112                          double target_pause_time_ms,
 113                          const G1DefaultPolicy* policy) :
 114     _during_cm(during_cm),
 115     _base_time_ms(base_time_ms),
 116     _base_free_regions(base_free_regions),
 117     _target_pause_time_ms(target_pause_time_ms),
 118     _policy(policy) {}
 119 
 120   bool will_fit(uint young_length) const {
 121     if (young_length >= _base_free_regions) {
 122       // end condition 1: not enough space for the young regions
 123       return false;
 124     }
 125 
 126     const double accum_surv_rate = _policy->accum_yg_surv_rate_pred((int) young_length - 1);
 127     const size_t bytes_to_copy =
 128                  (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 129     const double copy_time_ms =
 130       _policy->analytics()->predict_object_copy_time_ms(bytes_to_copy, _during_cm);
 131     const double young_other_time_ms = _policy->analytics()->predict_young_other_time_ms(young_length);
 132     const double pause_time_ms = _base_time_ms + copy_time_ms + young_other_time_ms;
 133     if (pause_time_ms > _target_pause_time_ms) {
 134       // end condition 2: prediction is over the target pause time
 135       return false;
 136     }
 137 
 138     const size_t free_bytes = (_base_free_regions - young_length) * HeapRegion::GrainBytes;
 139 
 140     // When copying, we will likely need more bytes free than is live in the region.
 141     // Add some safety margin to factor in the confidence of our guess, and the
 142     // natural expected waste.
 143     // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 144     // of the calculation: the lower the confidence, the more headroom.
 145     // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 146     // copying due to anticipated waste in the PLABs.
 147     const double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 148     const size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
 149 
 150     if (expected_bytes_to_copy > free_bytes) {
 151       // end condition 3: out-of-space
 152       return false;
 153     }
 154 
 155     // success!
 156     return true;
 157   }
 158 };
 159 
 160 void G1DefaultPolicy::record_new_heap_size(uint new_number_of_regions) {
 161   // re-calculate the necessary reserve
 162   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 163   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 164   // smaller than 1.0) we'll get 1.
 165   _reserve_regions = (uint) ceil(reserve_regions_d);
 166 
 167   _young_gen_sizer.heap_size_changed(new_number_of_regions);
 168 
 169   _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes);
 170 }
 171 
 172 uint G1DefaultPolicy::calculate_young_list_desired_min_length(uint base_min_length) const {
 173   uint desired_min_length = 0;
 174   if (adaptive_young_list_length()) {
 175     if (_analytics->num_alloc_rate_ms() > 3) {
 176       double now_sec = os::elapsedTime();
 177       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 178       double alloc_rate_ms = _analytics->predict_alloc_rate_ms();
 179       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 180     } else {
 181       // otherwise we don't have enough info to make the prediction
 182     }
 183   }
 184   desired_min_length += base_min_length;
 185   // make sure we don't go below any user-defined minimum bound
 186   return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length);
 187 }
 188 
 189 uint G1DefaultPolicy::calculate_young_list_desired_max_length() const {
 190   // Here, we might want to also take into account any additional
 191   // constraints (i.e., user-defined minimum bound). Currently, we
 192   // effectively don't set this bound.
 193   return _young_gen_sizer.max_desired_young_length();
 194 }
 195 
 196 uint G1DefaultPolicy::update_young_list_max_and_target_length() {
 197   return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());
 198 }
 199 
 200 uint G1DefaultPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 201   uint unbounded_target_length = update_young_list_target_length(rs_lengths);
 202   update_max_gc_locker_expansion();
 203   return unbounded_target_length;
 204 }
 205 
 206 uint G1DefaultPolicy::update_young_list_target_length(size_t rs_lengths) {
 207   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
 208   _young_list_target_length = young_lengths.first;
 209   return young_lengths.second;
 210 }
 211 
 212 G1DefaultPolicy::YoungTargetLengths G1DefaultPolicy::young_list_target_lengths(size_t rs_lengths) const {
 213   YoungTargetLengths result;
 214 
 215   // Calculate the absolute and desired min bounds first.
 216 
 217   // This is how many young regions we already have (currently: the survivors).
 218   const uint base_min_length = _g1->survivor_regions_count();
 219   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 220   // This is the absolute minimum young length. Ensure that we
 221   // will at least have one eden region available for allocation.
 222   uint absolute_min_length = base_min_length + MAX2(_g1->eden_regions_count(), (uint)1);
 223   // If we shrank the young list target it should not shrink below the current size.
 224   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 225   // Calculate the absolute and desired max bounds.
 226 
 227   uint desired_max_length = calculate_young_list_desired_max_length();
 228 
 229   uint young_list_target_length = 0;
 230   if (adaptive_young_list_length()) {
 231     if (collector_state()->gcs_are_young()) {
 232       young_list_target_length =
 233                         calculate_young_list_target_length(rs_lengths,
 234                                                            base_min_length,
 235                                                            desired_min_length,
 236                                                            desired_max_length);
 237     } else {
 238       // Don't calculate anything and let the code below bound it to
 239       // the desired_min_length, i.e., do the next GC as soon as
 240       // possible to maximize how many old regions we can add to it.
 241     }
 242   } else {
 243     // The user asked for a fixed young gen so we'll fix the young gen
 244     // whether the next GC is young or mixed.
 245     young_list_target_length = _young_list_fixed_length;
 246   }
 247 
 248   result.second = young_list_target_length;
 249 
 250   // We will try our best not to "eat" into the reserve.
 251   uint absolute_max_length = 0;
 252   if (_free_regions_at_end_of_collection > _reserve_regions) {
 253     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 254   }
 255   if (desired_max_length > absolute_max_length) {
 256     desired_max_length = absolute_max_length;
 257   }
 258 
 259   // Make sure we don't go over the desired max length, nor under the
 260   // desired min length. In case they clash, desired_min_length wins
 261   // which is why that test is second.
 262   if (young_list_target_length > desired_max_length) {
 263     young_list_target_length = desired_max_length;
 264   }
 265   if (young_list_target_length < desired_min_length) {
 266     young_list_target_length = desired_min_length;
 267   }
 268 
 269   assert(young_list_target_length > base_min_length,
 270          "we should be able to allocate at least one eden region");
 271   assert(young_list_target_length >= absolute_min_length, "post-condition");
 272 
 273   result.first = young_list_target_length;
 274   return result;
 275 }
 276 
 277 uint
 278 G1DefaultPolicy::calculate_young_list_target_length(size_t rs_lengths,
 279                                                     uint base_min_length,
 280                                                     uint desired_min_length,
 281                                                     uint desired_max_length) const {
 282   assert(adaptive_young_list_length(), "pre-condition");
 283   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 284 
 285   // In case some edge-condition makes the desired max length too small...
 286   if (desired_max_length <= desired_min_length) {
 287     return desired_min_length;
 288   }
 289 
 290   // We'll adjust min_young_length and max_young_length not to include
 291   // the already allocated young regions (i.e., so they reflect the
 292   // min and max eden regions we'll allocate). The base_min_length
 293   // will be reflected in the predictions by the
 294   // survivor_regions_evac_time prediction.
 295   assert(desired_min_length > base_min_length, "invariant");
 296   uint min_young_length = desired_min_length - base_min_length;
 297   assert(desired_max_length > base_min_length, "invariant");
 298   uint max_young_length = desired_max_length - base_min_length;
 299 
 300   const double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 301   const double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 302   const size_t pending_cards = _analytics->predict_pending_cards();
 303   const size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();
 304   const size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true);
 305   const double base_time_ms =
 306     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 307     survivor_regions_evac_time;
 308   const uint available_free_regions = _free_regions_at_end_of_collection;
 309   const uint base_free_regions =
 310     available_free_regions > _reserve_regions ? available_free_regions - _reserve_regions : 0;
 311 
 312   // Here, we will make sure that the shortest young length that
 313   // makes sense fits within the target pause time.
 314 
 315   G1YoungLengthPredictor p(collector_state()->during_concurrent_mark(),
 316                            base_time_ms,
 317                            base_free_regions,
 318                            target_pause_time_ms,
 319                            this);
 320   if (p.will_fit(min_young_length)) {
 321     // The shortest young length will fit into the target pause time;
 322     // we'll now check whether the absolute maximum number of young
 323     // regions will fit in the target pause time. If not, we'll do
 324     // a binary search between min_young_length and max_young_length.
 325     if (p.will_fit(max_young_length)) {
 326       // The maximum young length will fit into the target pause time.
 327       // We are done so set min young length to the maximum length (as
 328       // the result is assumed to be returned in min_young_length).
 329       min_young_length = max_young_length;
 330     } else {
 331       // The maximum possible number of young regions will not fit within
 332       // the target pause time so we'll search for the optimal
 333       // length. The loop invariants are:
 334       //
 335       // min_young_length < max_young_length
 336       // min_young_length is known to fit into the target pause time
 337       // max_young_length is known not to fit into the target pause time
 338       //
 339       // Going into the loop we know the above hold as we've just
 340       // checked them. Every time around the loop we check whether
 341       // the middle value between min_young_length and
 342       // max_young_length fits into the target pause time. If it
 343       // does, it becomes the new min. If it doesn't, it becomes
 344       // the new max. This way we maintain the loop invariants.
 345 
 346       assert(min_young_length < max_young_length, "invariant");
 347       uint diff = (max_young_length - min_young_length) / 2;
 348       while (diff > 0) {
 349         uint young_length = min_young_length + diff;
 350         if (p.will_fit(young_length)) {
 351           min_young_length = young_length;
 352         } else {
 353           max_young_length = young_length;
 354         }
 355         assert(min_young_length <  max_young_length, "invariant");
 356         diff = (max_young_length - min_young_length) / 2;
 357       }
 358       // The results is min_young_length which, according to the
 359       // loop invariants, should fit within the target pause time.
 360 
 361       // These are the post-conditions of the binary search above:
 362       assert(min_young_length < max_young_length,
 363              "otherwise we should have discovered that max_young_length "
 364              "fits into the pause target and not done the binary search");
 365       assert(p.will_fit(min_young_length),
 366              "min_young_length, the result of the binary search, should "
 367              "fit into the pause target");
 368       assert(!p.will_fit(min_young_length + 1),
 369              "min_young_length, the result of the binary search, should be "
 370              "optimal, so no larger length should fit into the pause target");
 371     }
 372   } else {
 373     // Even the minimum length doesn't fit into the pause time
 374     // target, return it as the result nevertheless.
 375   }
 376   return base_min_length + min_young_length;
 377 }
 378 
 379 double G1DefaultPolicy::predict_survivor_regions_evac_time() const {
 380   double survivor_regions_evac_time = 0.0;
 381   const GrowableArray<HeapRegion*>* survivor_regions = _g1->survivor()->regions();
 382 
 383   for (GrowableArrayIterator<HeapRegion*> it = survivor_regions->begin();
 384        it != survivor_regions->end();
 385        ++it) {
 386     survivor_regions_evac_time += predict_region_elapsed_time_ms(*it, collector_state()->gcs_are_young());
 387   }
 388   return survivor_regions_evac_time;
 389 }
 390 
 391 void G1DefaultPolicy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {
 392   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 393 
 394   if (rs_lengths > _rs_lengths_prediction) {
 395     // add 10% to avoid having to recalculate often
 396     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 397     update_rs_lengths_prediction(rs_lengths_prediction);
 398 
 399     update_young_list_max_and_target_length(rs_lengths_prediction);
 400   }
 401 }
 402 
 403 void G1DefaultPolicy::update_rs_lengths_prediction() {
 404   update_rs_lengths_prediction(_analytics->predict_rs_lengths());
 405 }
 406 
 407 void G1DefaultPolicy::update_rs_lengths_prediction(size_t prediction) {
 408   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 409     _rs_lengths_prediction = prediction;
 410   }
 411 }
 412 
 413 void G1DefaultPolicy::record_full_collection_start() {
 414   _full_collection_start_sec = os::elapsedTime();
 415   // Release the future to-space so that it is available for compaction into.
 416   collector_state()->set_full_collection(true);
 417 }
 418 
 419 void G1DefaultPolicy::record_full_collection_end() {
 420   // Consider this like a collection pause for the purposes of allocation
 421   // since last pause.
 422   double end_sec = os::elapsedTime();
 423   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 424   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 425 
 426   _analytics->update_recent_gc_times(end_sec, full_gc_time_ms);
 427 
 428   collector_state()->set_full_collection(false);
 429 
 430   // "Nuke" the heuristics that control the young/mixed GC
 431   // transitions and make sure we start with young GCs after the Full GC.
 432   collector_state()->set_gcs_are_young(true);
 433   collector_state()->set_last_young_gc(false);
 434   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 435   collector_state()->set_during_initial_mark_pause(false);
 436   collector_state()->set_in_marking_window(false);
 437   collector_state()->set_in_marking_window_im(false);
 438 
 439   _short_lived_surv_rate_group->start_adding_regions();
 440   // also call this on any additional surv rate groups
 441 
 442   _free_regions_at_end_of_collection = _g1->num_free_regions();
 443   // Reset survivors SurvRateGroup.
 444   _survivor_surv_rate_group->reset();
 445   update_young_list_max_and_target_length();
 446   update_rs_lengths_prediction();
 447   cset_chooser()->clear();
 448 
 449   _bytes_allocated_in_old_since_last_gc = 0;
 450 
 451   record_pause(FullGC, _full_collection_start_sec, end_sec);
 452 }
 453 
 454 void G1DefaultPolicy::record_collection_pause_start(double start_time_sec) {
 455   // We only need to do this here as the policy will only be applied
 456   // to the GC we're about to start. so, no point is calculating this
 457   // every time we calculate / recalculate the target young length.
 458   update_survivors_policy();
 459 
 460   assert(_g1->used() == _g1->recalculate_used(),
 461          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 462          _g1->used(), _g1->recalculate_used());
 463 
 464   phase_times()->record_cur_collection_start_sec(start_time_sec);
 465   _pending_cards = _g1->pending_card_num();
 466 
 467   _collection_set->reset_bytes_used_before();
 468   _bytes_copied_during_gc = 0;
 469 
 470   collector_state()->set_last_gc_was_young(false);
 471 
 472   // do that for any other surv rate groups
 473   _short_lived_surv_rate_group->stop_adding_regions();
 474   _survivors_age_table.clear();
 475 
 476   assert(_g1->collection_set()->verify_young_ages(), "region age verification failed");
 477 }
 478 
 479 void G1DefaultPolicy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) {
 480   collector_state()->set_during_marking(true);
 481   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 482   collector_state()->set_during_initial_mark_pause(false);
 483 }
 484 
 485 void G1DefaultPolicy::record_concurrent_mark_remark_start() {
 486   _mark_remark_start_sec = os::elapsedTime();
 487   collector_state()->set_during_marking(false);
 488 }
 489 
 490 void G1DefaultPolicy::record_concurrent_mark_remark_end() {
 491   double end_time_sec = os::elapsedTime();
 492   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 493   _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms);
 494   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
 495 
 496   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 497 }
 498 
 499 void G1DefaultPolicy::record_concurrent_mark_cleanup_start() {
 500   _mark_cleanup_start_sec = os::elapsedTime();
 501 }
 502 
 503 void G1DefaultPolicy::record_concurrent_mark_cleanup_completed() {
 504   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 505                                                               "skip last young-only gc");
 506   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 507   // We skip the marking phase.
 508   if (!should_continue_with_reclaim) {
 509     abort_time_to_mixed_tracking();
 510   }
 511   collector_state()->set_in_marking_window(false);
 512 }
 513 
 514 double G1DefaultPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 515   return phase_times()->average_time_ms(phase);
 516 }
 517 
 518 double G1DefaultPolicy::young_other_time_ms() const {
 519   return phase_times()->young_cset_choice_time_ms() +
 520          phase_times()->average_time_ms(G1GCPhaseTimes::YoungFreeCSet);
 521 }
 522 
 523 double G1DefaultPolicy::non_young_other_time_ms() const {
 524   return phase_times()->non_young_cset_choice_time_ms() +
 525          phase_times()->average_time_ms(G1GCPhaseTimes::NonYoungFreeCSet);
 526 }
 527 
 528 double G1DefaultPolicy::other_time_ms(double pause_time_ms) const {
 529   return pause_time_ms - phase_times()->cur_collection_par_time_ms();
 530 }
 531 
 532 double G1DefaultPolicy::constant_other_time_ms(double pause_time_ms) const {
 533   return other_time_ms(pause_time_ms) - phase_times()->total_free_cset_time_ms();
 534 }
 535 
 536 CollectionSetChooser* G1DefaultPolicy::cset_chooser() const {
 537   return _collection_set->cset_chooser();
 538 }
 539 
 540 bool G1DefaultPolicy::about_to_start_mixed_phase() const {
 541   return _g1->concurrent_mark()->cm_thread()->during_cycle() || collector_state()->last_young_gc();
 542 }
 543 
 544 bool G1DefaultPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 545   if (about_to_start_mixed_phase()) {
 546     return false;
 547   }
 548 
 549   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 550 
 551   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 552   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 553   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 554 
 555   bool result = false;
 556   if (marking_request_bytes > marking_initiating_used_threshold) {
 557     result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
 558     log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
 559                               result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
 560                               cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
 561   }
 562 
 563   return result;
 564 }
 565 
 566 // Anything below that is considered to be zero
 567 #define MIN_TIMER_GRANULARITY 0.0000001
 568 
 569 void G1DefaultPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
 570   double end_time_sec = os::elapsedTime();
 571 
 572   size_t cur_used_bytes = _g1->used();
 573   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 574   bool last_pause_included_initial_mark = false;
 575   bool update_stats = !_g1->evacuation_failed();
 576 
 577   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
 578 
 579   _collection_pause_end_millis = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
 580 
 581   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
 582   if (last_pause_included_initial_mark) {
 583     record_concurrent_mark_init_end(0.0);
 584   } else {
 585     maybe_start_marking();
 586   }
 587 
 588   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms());
 589   if (app_time_ms < MIN_TIMER_GRANULARITY) {
 590     // This usually happens due to the timer not having the required
 591     // granularity. Some Linuxes are the usual culprits.
 592     // We'll just set it to something (arbitrarily) small.
 593     app_time_ms = 1.0;
 594   }
 595 
 596   if (update_stats) {
 597     // We maintain the invariant that all objects allocated by mutator
 598     // threads will be allocated out of eden regions. So, we can use
 599     // the eden region number allocated since the previous GC to
 600     // calculate the application's allocate rate. The only exception
 601     // to that is humongous objects that are allocated separately. But
 602     // given that humongous object allocations do not really affect
 603     // either the pause's duration nor when the next pause will take
 604     // place we can safely ignore them here.
 605     uint regions_allocated = _collection_set->eden_region_length();
 606     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
 607     _analytics->report_alloc_rate_ms(alloc_rate_ms);
 608 
 609     double interval_ms =
 610       (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0;
 611     _analytics->update_recent_gc_times(end_time_sec, pause_time_ms);
 612     _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms);
 613   }
 614 
 615   bool new_in_marking_window = collector_state()->in_marking_window();
 616   bool new_in_marking_window_im = false;
 617   if (last_pause_included_initial_mark) {
 618     new_in_marking_window = true;
 619     new_in_marking_window_im = true;
 620   }
 621 
 622   if (collector_state()->last_young_gc()) {
 623     // This is supposed to to be the "last young GC" before we start
 624     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
 625     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
 626 
 627     if (next_gc_should_be_mixed("start mixed GCs",
 628                                 "do not start mixed GCs")) {
 629       collector_state()->set_gcs_are_young(false);
 630     } else {
 631       // We aborted the mixed GC phase early.
 632       abort_time_to_mixed_tracking();
 633     }
 634 
 635     collector_state()->set_last_young_gc(false);
 636   }
 637 
 638   if (!collector_state()->last_gc_was_young()) {
 639     // This is a mixed GC. Here we decide whether to continue doing
 640     // mixed GCs or not.
 641     if (!next_gc_should_be_mixed("continue mixed GCs",
 642                                  "do not continue mixed GCs")) {
 643       collector_state()->set_gcs_are_young(true);
 644 
 645       maybe_start_marking();
 646     }
 647   }
 648 
 649   _short_lived_surv_rate_group->start_adding_regions();
 650   // Do that for any other surv rate groups
 651 
 652   double scan_hcc_time_ms = G1HotCardCache::default_use_cache() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;
 653 
 654   if (update_stats) {
 655     double cost_per_card_ms = 0.0;
 656     if (_pending_cards > 0) {
 657       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;
 658       _analytics->report_cost_per_card_ms(cost_per_card_ms);
 659     }
 660     _analytics->report_cost_scan_hcc(scan_hcc_time_ms);
 661 
 662     double cost_per_entry_ms = 0.0;
 663     if (cards_scanned > 10) {
 664       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
 665       _analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young());
 666     }
 667 
 668     if (_max_rs_lengths > 0) {
 669       double cards_per_entry_ratio =
 670         (double) cards_scanned / (double) _max_rs_lengths;
 671       _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young());
 672     }
 673 
 674     // This is defensive. For a while _max_rs_lengths could get
 675     // smaller than _recorded_rs_lengths which was causing
 676     // rs_length_diff to get very large and mess up the RSet length
 677     // predictions. The reason was unsafe concurrent updates to the
 678     // _inc_cset_recorded_rs_lengths field which the code below guards
 679     // against (see CR 7118202). This bug has now been fixed (see CR
 680     // 7119027). However, I'm still worried that
 681     // _inc_cset_recorded_rs_lengths might still end up somewhat
 682     // inaccurate. The concurrent refinement thread calculates an
 683     // RSet's length concurrently with other CR threads updating it
 684     // which might cause it to calculate the length incorrectly (if,
 685     // say, it's in mid-coarsening). So I'll leave in the defensive
 686     // conditional below just in case.
 687     size_t rs_length_diff = 0;
 688     size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();
 689     if (_max_rs_lengths > recorded_rs_lengths) {
 690       rs_length_diff = _max_rs_lengths - recorded_rs_lengths;
 691     }
 692     _analytics->report_rs_length_diff((double) rs_length_diff);
 693 
 694     size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
 695     size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes;
 696     double cost_per_byte_ms = 0.0;
 697 
 698     if (copied_bytes > 0) {
 699       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
 700       _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window());
 701     }
 702 
 703     if (_collection_set->young_region_length() > 0) {
 704       _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() /
 705                                                         _collection_set->young_region_length());
 706     }
 707 
 708     if (_collection_set->old_region_length() > 0) {
 709       _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() /
 710                                                             _collection_set->old_region_length());
 711     }
 712 
 713     _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms));
 714 
 715     _analytics->report_pending_cards((double) _pending_cards);
 716     _analytics->report_rs_lengths((double) _max_rs_lengths);
 717   }
 718 
 719   collector_state()->set_in_marking_window(new_in_marking_window);
 720   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
 721   _free_regions_at_end_of_collection = _g1->num_free_regions();
 722   // IHOP control wants to know the expected young gen length if it were not
 723   // restrained by the heap reserve. Using the actual length would make the
 724   // prediction too small and the limit the young gen every time we get to the
 725   // predicted target occupancy.
 726   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
 727   update_rs_lengths_prediction();
 728 
 729   update_ihop_prediction(app_time_ms / 1000.0,
 730                          _bytes_allocated_in_old_since_last_gc,
 731                          last_unrestrained_young_length * HeapRegion::GrainBytes);
 732   _bytes_allocated_in_old_since_last_gc = 0;
 733 
 734   _ihop_control->send_trace_event(_g1->gc_tracer_stw());
 735 
 736   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
 737   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
 738 
 739   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
 740     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
 741                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
 742                                 update_rs_time_goal_ms, scan_hcc_time_ms);
 743 
 744     update_rs_time_goal_ms = 0;
 745   } else {
 746     update_rs_time_goal_ms -= scan_hcc_time_ms;
 747   }
 748   _g1->concurrent_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
 749                                       phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
 750                                       update_rs_time_goal_ms);
 751 
 752   cset_chooser()->verify();
 753 }
 754 
 755 G1IHOPControl* G1DefaultPolicy::create_ihop_control(const G1Predictions* predictor){
 756   if (G1UseAdaptiveIHOP) {
 757     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
 758                                      predictor,
 759                                      G1ReservePercent,
 760                                      G1HeapWastePercent);
 761   } else {
 762     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent);
 763   }
 764 }
 765 
 766 void G1DefaultPolicy::update_ihop_prediction(double mutator_time_s,
 767                                       size_t mutator_alloc_bytes,
 768                                       size_t young_gen_size) {
 769   // Always try to update IHOP prediction. Even evacuation failures give information
 770   // about e.g. whether to start IHOP earlier next time.
 771 
 772   // Avoid using really small application times that might create samples with
 773   // very high or very low values. They may be caused by e.g. back-to-back gcs.
 774   double const min_valid_time = 1e-6;
 775 
 776   bool report = false;
 777 
 778   double marking_to_mixed_time = -1.0;
 779   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
 780     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
 781     assert(marking_to_mixed_time > 0.0,
 782            "Initial mark to mixed time must be larger than zero but is %.3f",
 783            marking_to_mixed_time);
 784     if (marking_to_mixed_time > min_valid_time) {
 785       _ihop_control->update_marking_length(marking_to_mixed_time);
 786       report = true;
 787     }
 788   }
 789 
 790   // As an approximation for the young gc promotion rates during marking we use
 791   // all of them. In many applications there are only a few if any young gcs during
 792   // marking, which makes any prediction useless. This increases the accuracy of the
 793   // prediction.
 794   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
 795     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
 796     report = true;
 797   }
 798 
 799   if (report) {
 800     report_ihop_statistics();
 801   }
 802 }
 803 
 804 void G1DefaultPolicy::report_ihop_statistics() {
 805   _ihop_control->print();
 806 }
 807 
 808 void G1DefaultPolicy::print_phases() {
 809   phase_times()->print();
 810 }
 811 
 812 double G1DefaultPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
 813   TruncatedSeq* seq = surv_rate_group->get_seq(age);
 814   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
 815   double pred = _predictor.get_new_prediction(seq);
 816   if (pred > 1.0) {
 817     pred = 1.0;
 818   }
 819   return pred;
 820 }
 821 
 822 double G1DefaultPolicy::accum_yg_surv_rate_pred(int age) const {
 823   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
 824 }
 825 
 826 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
 827                                               size_t scanned_cards) const {
 828   return
 829     _analytics->predict_rs_update_time_ms(pending_cards) +
 830     _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) +
 831     _analytics->predict_constant_other_time_ms();
 832 }
 833 
 834 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
 835   size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();
 836   size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young());
 837   return predict_base_elapsed_time_ms(pending_cards, card_num);
 838 }
 839 
 840 size_t G1DefaultPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
 841   size_t bytes_to_copy;
 842   if (hr->is_marked())
 843     bytes_to_copy = hr->max_live_bytes();
 844   else {
 845     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
 846     int age = hr->age_in_surv_rate_group();
 847     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
 848     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
 849   }
 850   return bytes_to_copy;
 851 }
 852 
 853 double G1DefaultPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
 854                                                 bool for_young_gc) const {
 855   size_t rs_length = hr->rem_set()->occupied();
 856   // Predicting the number of cards is based on which type of GC
 857   // we're predicting for.
 858   size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc);
 859   size_t bytes_to_copy = predict_bytes_to_copy(hr);
 860 
 861   double region_elapsed_time_ms =
 862     _analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) +
 863     _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark());
 864 
 865   // The prediction of the "other" time for this region is based
 866   // upon the region type and NOT the GC type.
 867   if (hr->is_young()) {
 868     region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1);
 869   } else {
 870     region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1);
 871   }
 872   return region_elapsed_time_ms;
 873 }
 874 
 875 bool G1DefaultPolicy::should_allocate_mutator_region() const {
 876   uint young_list_length = _g1->young_regions_count();
 877   uint young_list_target_length = _young_list_target_length;
 878   return young_list_length < young_list_target_length;
 879 }
 880 
 881 bool G1DefaultPolicy::can_expand_young_list() const {
 882   uint young_list_length = _g1->young_regions_count();
 883   uint young_list_max_length = _young_list_max_length;
 884   return young_list_length < young_list_max_length;
 885 }
 886 
 887 bool G1DefaultPolicy::adaptive_young_list_length() const {
 888   return _young_gen_sizer.adaptive_young_list_length();
 889 }
 890 
 891 size_t G1DefaultPolicy::desired_survivor_size() const {
 892   size_t const survivor_capacity = HeapRegion::GrainWords * _max_survivor_regions;
 893   return (size_t)((((double)survivor_capacity) * TargetSurvivorRatio) / 100);
 894 }
 895 
 896 void G1DefaultPolicy::print_age_table() {
 897   _survivors_age_table.print_age_table(_tenuring_threshold);
 898 }
 899 
 900 void G1DefaultPolicy::update_max_gc_locker_expansion() {
 901   uint expansion_region_num = 0;
 902   if (GCLockerEdenExpansionPercent > 0) {
 903     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
 904     double expansion_region_num_d = perc * (double) _young_list_target_length;
 905     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
 906     // less than 1.0) we'll get 1.
 907     expansion_region_num = (uint) ceil(expansion_region_num_d);
 908   } else {
 909     assert(expansion_region_num == 0, "sanity");
 910   }
 911   _young_list_max_length = _young_list_target_length + expansion_region_num;
 912   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
 913 }
 914 
 915 // Calculates survivor space parameters.
 916 void G1DefaultPolicy::update_survivors_policy() {
 917   double max_survivor_regions_d =
 918                  (double) _young_list_target_length / (double) SurvivorRatio;
 919   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
 920   // smaller than 1.0) we'll get 1.
 921   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
 922 
 923   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(desired_survivor_size());
 924   if (UsePerfData) {
 925     _policy_counters->tenuring_threshold()->set_value(_tenuring_threshold);
 926     _policy_counters->desired_survivor_size()->set_value(desired_survivor_size() * oopSize);
 927   }
 928 }
 929 
 930 bool G1DefaultPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
 931   // We actually check whether we are marking here and not if we are in a
 932   // reclamation phase. This means that we will schedule a concurrent mark
 933   // even while we are still in the process of reclaiming memory.
 934   bool during_cycle = _g1->concurrent_mark()->cm_thread()->during_cycle();
 935   if (!during_cycle) {
 936     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
 937     collector_state()->set_initiate_conc_mark_if_possible(true);
 938     return true;
 939   } else {
 940     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
 941     return false;
 942   }
 943 }
 944 
 945 void G1DefaultPolicy::initiate_conc_mark() {
 946   collector_state()->set_during_initial_mark_pause(true);
 947   collector_state()->set_initiate_conc_mark_if_possible(false);
 948 }
 949 
 950 void G1DefaultPolicy::decide_on_conc_mark_initiation() {
 951   // We are about to decide on whether this pause will be an
 952   // initial-mark pause.
 953 
 954   // First, collector_state()->during_initial_mark_pause() should not be already set. We
 955   // will set it here if we have to. However, it should be cleared by
 956   // the end of the pause (it's only set for the duration of an
 957   // initial-mark pause).
 958   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
 959 
 960   if (collector_state()->initiate_conc_mark_if_possible()) {
 961     // We had noticed on a previous pause that the heap occupancy has
 962     // gone over the initiating threshold and we should start a
 963     // concurrent marking cycle. So we might initiate one.
 964 
 965     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
 966       // Initiate a new initial mark if there is no marking or reclamation going on.
 967       initiate_conc_mark();
 968       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
 969     } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
 970       // Initiate a user requested initial mark. An initial mark must be young only
 971       // GC, so the collector state must be updated to reflect this.
 972       collector_state()->set_gcs_are_young(true);
 973       collector_state()->set_last_young_gc(false);
 974 
 975       abort_time_to_mixed_tracking();
 976       initiate_conc_mark();
 977       log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
 978     } else {
 979       // The concurrent marking thread is still finishing up the
 980       // previous cycle. If we start one right now the two cycles
 981       // overlap. In particular, the concurrent marking thread might
 982       // be in the process of clearing the next marking bitmap (which
 983       // we will use for the next cycle if we start one). Starting a
 984       // cycle now will be bad given that parts of the marking
 985       // information might get cleared by the marking thread. And we
 986       // cannot wait for the marking thread to finish the cycle as it
 987       // periodically yields while clearing the next marking bitmap
 988       // and, if it's in a yield point, it's waiting for us to
 989       // finish. So, at this point we will not start a cycle and we'll
 990       // let the concurrent marking thread complete the last one.
 991       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
 992     }
 993   }
 994 }
 995 
 996 void G1DefaultPolicy::record_concurrent_mark_cleanup_end() {
 997   cset_chooser()->rebuild(_g1->workers(), _g1->num_regions());
 998 
 999   double end_sec = os::elapsedTime();
1000   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1001   _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms);
1002   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
1003 
1004   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1005 }
1006 
1007 double G1DefaultPolicy::reclaimable_bytes_percent(size_t reclaimable_bytes) const {
1008   return percent_of(reclaimable_bytes, _g1->capacity());
1009 }
1010 
1011 void G1DefaultPolicy::maybe_start_marking() {
1012   if (need_to_start_conc_mark("end of GC")) {
1013     // Note: this might have already been set, if during the last
1014     // pause we decided to start a cycle but at the beginning of
1015     // this pause we decided to postpone it. That's OK.
1016     collector_state()->set_initiate_conc_mark_if_possible(true);
1017   }
1018 }
1019 
1020 G1DefaultPolicy::PauseKind G1DefaultPolicy::young_gc_pause_kind() const {
1021   assert(!collector_state()->full_collection(), "must be");
1022   if (collector_state()->during_initial_mark_pause()) {
1023     assert(collector_state()->last_gc_was_young(), "must be");
1024     assert(!collector_state()->last_young_gc(), "must be");
1025     return InitialMarkGC;
1026   } else if (collector_state()->last_young_gc()) {
1027     assert(!collector_state()->during_initial_mark_pause(), "must be");
1028     assert(collector_state()->last_gc_was_young(), "must be");
1029     return LastYoungGC;
1030   } else if (!collector_state()->last_gc_was_young()) {
1031     assert(!collector_state()->during_initial_mark_pause(), "must be");
1032     assert(!collector_state()->last_young_gc(), "must be");
1033     return MixedGC;
1034   } else {
1035     assert(collector_state()->last_gc_was_young(), "must be");
1036     assert(!collector_state()->during_initial_mark_pause(), "must be");
1037     assert(!collector_state()->last_young_gc(), "must be");
1038     return YoungOnlyGC;
1039   }
1040 }
1041 
1042 void G1DefaultPolicy::record_pause(PauseKind kind, double start, double end) {
1043   // Manage the MMU tracker. For some reason it ignores Full GCs.
1044   if (kind != FullGC) {
1045     _mmu_tracker->add_pause(start, end);
1046   }
1047   // Manage the mutator time tracking from initial mark to first mixed gc.
1048   switch (kind) {
1049     case FullGC:
1050       abort_time_to_mixed_tracking();
1051       break;
1052     case Cleanup:
1053     case Remark:
1054     case YoungOnlyGC:
1055     case LastYoungGC:
1056       _initial_mark_to_mixed.add_pause(end - start);
1057       break;
1058     case InitialMarkGC:
1059       _initial_mark_to_mixed.record_initial_mark_end(end);
1060       break;
1061     case MixedGC:
1062       _initial_mark_to_mixed.record_mixed_gc_start(start);
1063       break;
1064     default:
1065       ShouldNotReachHere();
1066   }
1067 }
1068 
1069 void G1DefaultPolicy::abort_time_to_mixed_tracking() {
1070   _initial_mark_to_mixed.reset();
1071 }
1072 
1073 bool G1DefaultPolicy::next_gc_should_be_mixed(const char* true_action_str,
1074                                        const char* false_action_str) const {
1075   if (cset_chooser()->is_empty()) {
1076     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
1077     return false;
1078   }
1079 
1080   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1081   size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
1082   double reclaimable_percent = reclaimable_bytes_percent(reclaimable_bytes);
1083   double threshold = (double) G1HeapWastePercent;
1084   if (reclaimable_percent <= threshold) {
1085     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1086                         false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent);
1087     return false;
1088   }
1089   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1090                       true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent);
1091   return true;
1092 }
1093 
1094 uint G1DefaultPolicy::calc_min_old_cset_length() const {
1095   // The min old CSet region bound is based on the maximum desired
1096   // number of mixed GCs after a cycle. I.e., even if some old regions
1097   // look expensive, we should add them to the CSet anyway to make
1098   // sure we go through the available old regions in no more than the
1099   // maximum desired number of mixed GCs.
1100   //
1101   // The calculation is based on the number of marked regions we added
1102   // to the CSet chooser in the first place, not how many remain, so
1103   // that the result is the same during all mixed GCs that follow a cycle.
1104 
1105   const size_t region_num = (size_t) cset_chooser()->length();
1106   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1107   size_t result = region_num / gc_num;
1108   // emulate ceiling
1109   if (result * gc_num < region_num) {
1110     result += 1;
1111   }
1112   return (uint) result;
1113 }
1114 
1115 uint G1DefaultPolicy::calc_max_old_cset_length() const {
1116   // The max old CSet region bound is based on the threshold expressed
1117   // as a percentage of the heap size. I.e., it should bound the
1118   // number of old regions added to the CSet irrespective of how many
1119   // of them are available.
1120 
1121   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
1122   const size_t region_num = g1h->num_regions();
1123   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1124   size_t result = region_num * perc / 100;
1125   // emulate ceiling
1126   if (100 * result < region_num * perc) {
1127     result += 1;
1128   }
1129   return (uint) result;
1130 }
1131 
1132 void G1DefaultPolicy::finalize_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {
1133   double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms, survivor);
1134   _collection_set->finalize_old_part(time_remaining_ms);
1135 }
1136 
1137 void G1DefaultPolicy::transfer_survivors_to_cset(const G1SurvivorRegions* survivors) {
1138 
1139   // Add survivor regions to SurvRateGroup.
1140   note_start_adding_survivor_regions();
1141   finished_recalculating_age_indexes(true /* is_survivors */);
1142 
1143   HeapRegion* last = NULL;
1144   for (GrowableArrayIterator<HeapRegion*> it = survivors->regions()->begin();
1145        it != survivors->regions()->end();
1146        ++it) {
1147     HeapRegion* curr = *it;
1148     set_region_survivor(curr);
1149 
1150     // The region is a non-empty survivor so let's add it to
1151     // the incremental collection set for the next evacuation
1152     // pause.
1153     _collection_set->add_survivor_regions(curr);
1154 
1155     last = curr;
1156   }
1157   note_stop_adding_survivor_regions();
1158 
1159   // Don't clear the survivor list handles until the start of
1160   // the next evacuation pause - we need it in order to re-tag
1161   // the survivor regions from this evacuation pause as 'young'
1162   // at the start of the next.
1163 
1164   finished_recalculating_age_indexes(false /* is_survivors */);
1165 }
--- EOF ---