1 /*
   2  * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/concurrentMarkThread.inline.hpp"
  28 #include "gc/g1/g1Analytics.hpp"
  29 #include "gc/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc/g1/g1CollectionSet.hpp"
  31 #include "gc/g1/g1ConcurrentMark.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() :
  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(ParallelGCThreads)),
  67   _tenuring_threshold(MaxTenuringThreshold),
  68   _max_survivor_regions(0),
  69   _survivors_age_table(true) { }
  70 
  71 G1DefaultPolicy::~G1DefaultPolicy() {
  72   delete _ihop_control;
  73 }
  74 
  75 G1CollectorState* G1DefaultPolicy::collector_state() const { return _g1->collector_state(); }
  76 
  77 void G1DefaultPolicy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) {
  78   _g1 = g1h;
  79   _collection_set = collection_set;
  80 
  81   assert(Heap_lock->owned_by_self(), "Locking discipline.");
  82 
  83   if (!adaptive_young_list_length()) {
  84     _young_list_fixed_length = _young_gen_sizer.min_desired_young_length();
  85   }
  86   _young_gen_sizer.adjust_max_new_size(_g1->max_regions());
  87 
  88   _free_regions_at_end_of_collection = _g1->num_free_regions();
  89 
  90   update_young_list_max_and_target_length();
  91   // We may immediately start allocating regions and placing them on the
  92   // collection set list. Initialize the per-collection set info
  93   _collection_set->start_incremental_building();
  94 }
  95 
  96 void G1DefaultPolicy::note_gc_start() {
  97   phase_times()->note_gc_start();
  98 }
  99 
 100 bool G1DefaultPolicy::predict_will_fit(uint young_length,
 101                                        double base_time_ms,
 102                                        uint base_free_regions,
 103                                        double target_pause_time_ms) const {
 104   if (young_length >= base_free_regions) {
 105     // end condition 1: not enough space for the young regions
 106     return false;
 107   }
 108 
 109   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 110   size_t bytes_to_copy =
 111                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 112   double copy_time_ms = _analytics->predict_object_copy_time_ms(bytes_to_copy,
 113                                                                 collector_state()->during_concurrent_mark());
 114   double young_other_time_ms = _analytics->predict_young_other_time_ms(young_length);
 115   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 116   if (pause_time_ms > target_pause_time_ms) {
 117     // end condition 2: prediction is over the target pause time
 118     return false;
 119   }
 120 
 121   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 122 
 123   // When copying, we will likely need more bytes free than is live in the region.
 124   // Add some safety margin to factor in the confidence of our guess, and the
 125   // natural expected waste.
 126   // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 127   // of the calculation: the lower the confidence, the more headroom.
 128   // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 129   // copying due to anticipated waste in the PLABs.
 130   double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 131   size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
 132 
 133   if (expected_bytes_to_copy > free_bytes) {
 134     // end condition 3: out-of-space
 135     return false;
 136   }
 137 
 138   // success!
 139   return true;
 140 }
 141 
 142 void G1DefaultPolicy::record_new_heap_size(uint new_number_of_regions) {
 143   // re-calculate the necessary reserve
 144   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 145   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 146   // smaller than 1.0) we'll get 1.
 147   _reserve_regions = (uint) ceil(reserve_regions_d);
 148 
 149   _young_gen_sizer.heap_size_changed(new_number_of_regions);
 150 
 151   _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes);
 152 }
 153 
 154 uint G1DefaultPolicy::calculate_young_list_desired_min_length(uint base_min_length) const {
 155   uint desired_min_length = 0;
 156   if (adaptive_young_list_length()) {
 157     if (_analytics->num_alloc_rate_ms() > 3) {
 158       double now_sec = os::elapsedTime();
 159       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 160       double alloc_rate_ms = _analytics->predict_alloc_rate_ms();
 161       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 162     } else {
 163       // otherwise we don't have enough info to make the prediction
 164     }
 165   }
 166   desired_min_length += base_min_length;
 167   // make sure we don't go below any user-defined minimum bound
 168   return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length);
 169 }
 170 
 171 uint G1DefaultPolicy::calculate_young_list_desired_max_length() const {
 172   // Here, we might want to also take into account any additional
 173   // constraints (i.e., user-defined minimum bound). Currently, we
 174   // effectively don't set this bound.
 175   return _young_gen_sizer.max_desired_young_length();
 176 }
 177 
 178 uint G1DefaultPolicy::update_young_list_max_and_target_length() {
 179   return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());
 180 }
 181 
 182 uint G1DefaultPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
 183   uint unbounded_target_length = update_young_list_target_length(rs_lengths);
 184   update_max_gc_locker_expansion();
 185   return unbounded_target_length;
 186 }
 187 
 188 uint G1DefaultPolicy::update_young_list_target_length(size_t rs_lengths) {
 189   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
 190   _young_list_target_length = young_lengths.first;
 191   return young_lengths.second;
 192 }
 193 
 194 G1DefaultPolicy::YoungTargetLengths G1DefaultPolicy::young_list_target_lengths(size_t rs_lengths) const {
 195   YoungTargetLengths result;
 196 
 197   // Calculate the absolute and desired min bounds first.
 198 
 199   // This is how many young regions we already have (currently: the survivors).
 200   const uint base_min_length = _g1->survivor_regions_count();
 201   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 202   // This is the absolute minimum young length. Ensure that we
 203   // will at least have one eden region available for allocation.
 204   uint absolute_min_length = base_min_length + MAX2(_g1->eden_regions_count(), (uint)1);
 205   // If we shrank the young list target it should not shrink below the current size.
 206   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 207   // Calculate the absolute and desired max bounds.
 208 
 209   uint desired_max_length = calculate_young_list_desired_max_length();
 210 
 211   uint young_list_target_length = 0;
 212   if (adaptive_young_list_length()) {
 213     if (collector_state()->gcs_are_young()) {
 214       young_list_target_length =
 215                         calculate_young_list_target_length(rs_lengths,
 216                                                            base_min_length,
 217                                                            desired_min_length,
 218                                                            desired_max_length);
 219     } else {
 220       // Don't calculate anything and let the code below bound it to
 221       // the desired_min_length, i.e., do the next GC as soon as
 222       // possible to maximize how many old regions we can add to it.
 223     }
 224   } else {
 225     // The user asked for a fixed young gen so we'll fix the young gen
 226     // whether the next GC is young or mixed.
 227     young_list_target_length = _young_list_fixed_length;
 228   }
 229 
 230   result.second = young_list_target_length;
 231 
 232   // We will try our best not to "eat" into the reserve.
 233   uint absolute_max_length = 0;
 234   if (_free_regions_at_end_of_collection > _reserve_regions) {
 235     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 236   }
 237   if (desired_max_length > absolute_max_length) {
 238     desired_max_length = absolute_max_length;
 239   }
 240 
 241   // Make sure we don't go over the desired max length, nor under the
 242   // desired min length. In case they clash, desired_min_length wins
 243   // which is why that test is second.
 244   if (young_list_target_length > desired_max_length) {
 245     young_list_target_length = desired_max_length;
 246   }
 247   if (young_list_target_length < desired_min_length) {
 248     young_list_target_length = desired_min_length;
 249   }
 250 
 251   assert(young_list_target_length > base_min_length,
 252          "we should be able to allocate at least one eden region");
 253   assert(young_list_target_length >= absolute_min_length, "post-condition");
 254 
 255   result.first = young_list_target_length;
 256   return result;
 257 }
 258 
 259 uint
 260 G1DefaultPolicy::calculate_young_list_target_length(size_t rs_lengths,
 261                                                     uint base_min_length,
 262                                                     uint desired_min_length,
 263                                                     uint desired_max_length) const {
 264   assert(adaptive_young_list_length(), "pre-condition");
 265   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 266 
 267   // In case some edge-condition makes the desired max length too small...
 268   if (desired_max_length <= desired_min_length) {
 269     return desired_min_length;
 270   }
 271 
 272   // We'll adjust min_young_length and max_young_length not to include
 273   // the already allocated young regions (i.e., so they reflect the
 274   // min and max eden regions we'll allocate). The base_min_length
 275   // will be reflected in the predictions by the
 276   // survivor_regions_evac_time prediction.
 277   assert(desired_min_length > base_min_length, "invariant");
 278   uint min_young_length = desired_min_length - base_min_length;
 279   assert(desired_max_length > base_min_length, "invariant");
 280   uint max_young_length = desired_max_length - base_min_length;
 281 
 282   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 283   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 284   size_t pending_cards = _analytics->predict_pending_cards();
 285   size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();
 286   size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true);
 287   double base_time_ms =
 288     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 289     survivor_regions_evac_time;
 290   uint available_free_regions = _free_regions_at_end_of_collection;
 291   uint base_free_regions = 0;
 292   if (available_free_regions > _reserve_regions) {
 293     base_free_regions = available_free_regions - _reserve_regions;
 294   }
 295 
 296   // Here, we will make sure that the shortest young length that
 297   // makes sense fits within the target pause time.
 298 
 299   if (predict_will_fit(min_young_length, base_time_ms,
 300                        base_free_regions, target_pause_time_ms)) {
 301     // The shortest young length will fit into the target pause time;
 302     // we'll now check whether the absolute maximum number of young
 303     // regions will fit in the target pause time. If not, we'll do
 304     // a binary search between min_young_length and max_young_length.
 305     if (predict_will_fit(max_young_length, base_time_ms,
 306                          base_free_regions, target_pause_time_ms)) {
 307       // The maximum young length will fit into the target pause time.
 308       // We are done so set min young length to the maximum length (as
 309       // the result is assumed to be returned in min_young_length).
 310       min_young_length = max_young_length;
 311     } else {
 312       // The maximum possible number of young regions will not fit within
 313       // the target pause time so we'll search for the optimal
 314       // length. The loop invariants are:
 315       //
 316       // min_young_length < max_young_length
 317       // min_young_length is known to fit into the target pause time
 318       // max_young_length is known not to fit into the target pause time
 319       //
 320       // Going into the loop we know the above hold as we've just
 321       // checked them. Every time around the loop we check whether
 322       // the middle value between min_young_length and
 323       // max_young_length fits into the target pause time. If it
 324       // does, it becomes the new min. If it doesn't, it becomes
 325       // the new max. This way we maintain the loop invariants.
 326 
 327       assert(min_young_length < max_young_length, "invariant");
 328       uint diff = (max_young_length - min_young_length) / 2;
 329       while (diff > 0) {
 330         uint young_length = min_young_length + diff;
 331         if (predict_will_fit(young_length, base_time_ms,
 332                              base_free_regions, target_pause_time_ms)) {
 333           min_young_length = young_length;
 334         } else {
 335           max_young_length = young_length;
 336         }
 337         assert(min_young_length <  max_young_length, "invariant");
 338         diff = (max_young_length - min_young_length) / 2;
 339       }
 340       // The results is min_young_length which, according to the
 341       // loop invariants, should fit within the target pause time.
 342 
 343       // These are the post-conditions of the binary search above:
 344       assert(min_young_length < max_young_length,
 345              "otherwise we should have discovered that max_young_length "
 346              "fits into the pause target and not done the binary search");
 347       assert(predict_will_fit(min_young_length, base_time_ms,
 348                               base_free_regions, target_pause_time_ms),
 349              "min_young_length, the result of the binary search, should "
 350              "fit into the pause target");
 351       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 352                                base_free_regions, target_pause_time_ms),
 353              "min_young_length, the result of the binary search, should be "
 354              "optimal, so no larger length should fit into the pause target");
 355     }
 356   } else {
 357     // Even the minimum length doesn't fit into the pause time
 358     // target, return it as the result nevertheless.
 359   }
 360   return base_min_length + min_young_length;
 361 }
 362 
 363 double G1DefaultPolicy::predict_survivor_regions_evac_time() const {
 364   double survivor_regions_evac_time = 0.0;
 365   const GrowableArray<HeapRegion*>* survivor_regions = _g1->survivor()->regions();
 366 
 367   for (GrowableArrayIterator<HeapRegion*> it = survivor_regions->begin();
 368        it != survivor_regions->end();
 369        ++it) {
 370     survivor_regions_evac_time += predict_region_elapsed_time_ms(*it, collector_state()->gcs_are_young());
 371   }
 372   return survivor_regions_evac_time;
 373 }
 374 
 375 void G1DefaultPolicy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {
 376   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 377 
 378   if (rs_lengths > _rs_lengths_prediction) {
 379     // add 10% to avoid having to recalculate often
 380     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 381     update_rs_lengths_prediction(rs_lengths_prediction);
 382 
 383     update_young_list_max_and_target_length(rs_lengths_prediction);
 384   }
 385 }
 386 
 387 void G1DefaultPolicy::update_rs_lengths_prediction() {
 388   update_rs_lengths_prediction(_analytics->predict_rs_lengths());
 389 }
 390 
 391 void G1DefaultPolicy::update_rs_lengths_prediction(size_t prediction) {
 392   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 393     _rs_lengths_prediction = prediction;
 394   }
 395 }
 396 
 397 void G1DefaultPolicy::record_full_collection_start() {
 398   _full_collection_start_sec = os::elapsedTime();
 399   // Release the future to-space so that it is available for compaction into.
 400   collector_state()->set_full_collection(true);
 401 }
 402 
 403 void G1DefaultPolicy::record_full_collection_end() {
 404   // Consider this like a collection pause for the purposes of allocation
 405   // since last pause.
 406   double end_sec = os::elapsedTime();
 407   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 408   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 409 
 410   _analytics->update_recent_gc_times(end_sec, full_gc_time_ms);
 411 
 412   collector_state()->set_full_collection(false);
 413 
 414   // "Nuke" the heuristics that control the young/mixed GC
 415   // transitions and make sure we start with young GCs after the Full GC.
 416   collector_state()->set_gcs_are_young(true);
 417   collector_state()->set_last_young_gc(false);
 418   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 419   collector_state()->set_during_initial_mark_pause(false);
 420   collector_state()->set_in_marking_window(false);
 421   collector_state()->set_in_marking_window_im(false);
 422 
 423   _short_lived_surv_rate_group->start_adding_regions();
 424   // also call this on any additional surv rate groups
 425 
 426   _free_regions_at_end_of_collection = _g1->num_free_regions();
 427   // Reset survivors SurvRateGroup.
 428   _survivor_surv_rate_group->reset();
 429   update_young_list_max_and_target_length();
 430   update_rs_lengths_prediction();
 431   cset_chooser()->clear();
 432 
 433   _bytes_allocated_in_old_since_last_gc = 0;
 434 
 435   record_pause(FullGC, _full_collection_start_sec, end_sec);
 436 }
 437 
 438 void G1DefaultPolicy::record_collection_pause_start(double start_time_sec) {
 439   // We only need to do this here as the policy will only be applied
 440   // to the GC we're about to start. so, no point is calculating this
 441   // every time we calculate / recalculate the target young length.
 442   update_survivors_policy();
 443 
 444   assert(_g1->used() == _g1->recalculate_used(),
 445          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 446          _g1->used(), _g1->recalculate_used());
 447 
 448   phase_times()->record_cur_collection_start_sec(start_time_sec);
 449   _pending_cards = _g1->pending_card_num();
 450 
 451   _collection_set->reset_bytes_used_before();
 452   _bytes_copied_during_gc = 0;
 453 
 454   collector_state()->set_last_gc_was_young(false);
 455 
 456   // do that for any other surv rate groups
 457   _short_lived_surv_rate_group->stop_adding_regions();
 458   _survivors_age_table.clear();
 459 
 460   assert(_g1->collection_set()->verify_young_ages(), "region age verification failed");
 461 }
 462 
 463 void G1DefaultPolicy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) {
 464   collector_state()->set_during_marking(true);
 465   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 466   collector_state()->set_during_initial_mark_pause(false);
 467 }
 468 
 469 void G1DefaultPolicy::record_concurrent_mark_remark_start() {
 470   _mark_remark_start_sec = os::elapsedTime();
 471   collector_state()->set_during_marking(false);
 472 }
 473 
 474 void G1DefaultPolicy::record_concurrent_mark_remark_end() {
 475   double end_time_sec = os::elapsedTime();
 476   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 477   _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms);
 478   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
 479 
 480   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 481 }
 482 
 483 void G1DefaultPolicy::record_concurrent_mark_cleanup_start() {
 484   _mark_cleanup_start_sec = os::elapsedTime();
 485 }
 486 
 487 void G1DefaultPolicy::record_concurrent_mark_cleanup_completed() {
 488   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 489                                                               "skip last young-only gc");
 490   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 491   // We skip the marking phase.
 492   if (!should_continue_with_reclaim) {
 493     abort_time_to_mixed_tracking();
 494   }
 495   collector_state()->set_in_marking_window(false);
 496 }
 497 
 498 double G1DefaultPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 499   return phase_times()->average_time_ms(phase);
 500 }
 501 
 502 double G1DefaultPolicy::young_other_time_ms() const {
 503   return phase_times()->young_cset_choice_time_ms() +
 504          phase_times()->average_time_ms(G1GCPhaseTimes::YoungFreeCSet);
 505 }
 506 
 507 double G1DefaultPolicy::non_young_other_time_ms() const {
 508   return phase_times()->non_young_cset_choice_time_ms() +
 509          phase_times()->average_time_ms(G1GCPhaseTimes::NonYoungFreeCSet);
 510 }
 511 
 512 double G1DefaultPolicy::other_time_ms(double pause_time_ms) const {
 513   return pause_time_ms - phase_times()->cur_collection_par_time_ms();
 514 }
 515 
 516 double G1DefaultPolicy::constant_other_time_ms(double pause_time_ms) const {
 517   return other_time_ms(pause_time_ms) - phase_times()->total_free_cset_time_ms();
 518 }
 519 
 520 CollectionSetChooser* G1DefaultPolicy::cset_chooser() const {
 521   return _collection_set->cset_chooser();
 522 }
 523 
 524 bool G1DefaultPolicy::about_to_start_mixed_phase() const {
 525   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 526 }
 527 
 528 bool G1DefaultPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 529   if (about_to_start_mixed_phase()) {
 530     return false;
 531   }
 532 
 533   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 534 
 535   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 536   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 537   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 538 
 539   bool result = false;
 540   if (marking_request_bytes > marking_initiating_used_threshold) {
 541     result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
 542     log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
 543                               result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
 544                               cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
 545   }
 546 
 547   return result;
 548 }
 549 
 550 // Anything below that is considered to be zero
 551 #define MIN_TIMER_GRANULARITY 0.0000001
 552 
 553 void G1DefaultPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
 554   double end_time_sec = os::elapsedTime();
 555 
 556   size_t cur_used_bytes = _g1->used();
 557   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 558   bool last_pause_included_initial_mark = false;
 559   bool update_stats = !_g1->evacuation_failed();
 560 
 561   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
 562 
 563   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
 564   if (last_pause_included_initial_mark) {
 565     record_concurrent_mark_init_end(0.0);
 566   } else {
 567     maybe_start_marking();
 568   }
 569 
 570   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms());
 571   if (app_time_ms < MIN_TIMER_GRANULARITY) {
 572     // This usually happens due to the timer not having the required
 573     // granularity. Some Linuxes are the usual culprits.
 574     // We'll just set it to something (arbitrarily) small.
 575     app_time_ms = 1.0;
 576   }
 577 
 578   if (update_stats) {
 579     // We maintain the invariant that all objects allocated by mutator
 580     // threads will be allocated out of eden regions. So, we can use
 581     // the eden region number allocated since the previous GC to
 582     // calculate the application's allocate rate. The only exception
 583     // to that is humongous objects that are allocated separately. But
 584     // given that humongous object allocations do not really affect
 585     // either the pause's duration nor when the next pause will take
 586     // place we can safely ignore them here.
 587     uint regions_allocated = _collection_set->eden_region_length();
 588     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
 589     _analytics->report_alloc_rate_ms(alloc_rate_ms);
 590 
 591     double interval_ms =
 592       (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0;
 593     _analytics->update_recent_gc_times(end_time_sec, pause_time_ms);
 594     _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms);
 595   }
 596 
 597   bool new_in_marking_window = collector_state()->in_marking_window();
 598   bool new_in_marking_window_im = false;
 599   if (last_pause_included_initial_mark) {
 600     new_in_marking_window = true;
 601     new_in_marking_window_im = true;
 602   }
 603 
 604   if (collector_state()->last_young_gc()) {
 605     // This is supposed to to be the "last young GC" before we start
 606     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
 607     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
 608 
 609     if (next_gc_should_be_mixed("start mixed GCs",
 610                                 "do not start mixed GCs")) {
 611       collector_state()->set_gcs_are_young(false);
 612     } else {
 613       // We aborted the mixed GC phase early.
 614       abort_time_to_mixed_tracking();
 615     }
 616 
 617     collector_state()->set_last_young_gc(false);
 618   }
 619 
 620   if (!collector_state()->last_gc_was_young()) {
 621     // This is a mixed GC. Here we decide whether to continue doing
 622     // mixed GCs or not.
 623     if (!next_gc_should_be_mixed("continue mixed GCs",
 624                                  "do not continue mixed GCs")) {
 625       collector_state()->set_gcs_are_young(true);
 626 
 627       maybe_start_marking();
 628     }
 629   }
 630 
 631   _short_lived_surv_rate_group->start_adding_regions();
 632   // Do that for any other surv rate groups
 633 
 634   double scan_hcc_time_ms = G1HotCardCache::default_use_cache() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;
 635 
 636   if (update_stats) {
 637     double cost_per_card_ms = 0.0;
 638     if (_pending_cards > 0) {
 639       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;
 640       _analytics->report_cost_per_card_ms(cost_per_card_ms);
 641     }
 642     _analytics->report_cost_scan_hcc(scan_hcc_time_ms);
 643 
 644     double cost_per_entry_ms = 0.0;
 645     if (cards_scanned > 10) {
 646       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
 647       _analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young());
 648     }
 649 
 650     if (_max_rs_lengths > 0) {
 651       double cards_per_entry_ratio =
 652         (double) cards_scanned / (double) _max_rs_lengths;
 653       _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young());
 654     }
 655 
 656     // This is defensive. For a while _max_rs_lengths could get
 657     // smaller than _recorded_rs_lengths which was causing
 658     // rs_length_diff to get very large and mess up the RSet length
 659     // predictions. The reason was unsafe concurrent updates to the
 660     // _inc_cset_recorded_rs_lengths field which the code below guards
 661     // against (see CR 7118202). This bug has now been fixed (see CR
 662     // 7119027). However, I'm still worried that
 663     // _inc_cset_recorded_rs_lengths might still end up somewhat
 664     // inaccurate. The concurrent refinement thread calculates an
 665     // RSet's length concurrently with other CR threads updating it
 666     // which might cause it to calculate the length incorrectly (if,
 667     // say, it's in mid-coarsening). So I'll leave in the defensive
 668     // conditional below just in case.
 669     size_t rs_length_diff = 0;
 670     size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();
 671     if (_max_rs_lengths > recorded_rs_lengths) {
 672       rs_length_diff = _max_rs_lengths - recorded_rs_lengths;
 673     }
 674     _analytics->report_rs_length_diff((double) rs_length_diff);
 675 
 676     size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
 677     size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes;
 678     double cost_per_byte_ms = 0.0;
 679 
 680     if (copied_bytes > 0) {
 681       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
 682       _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window());
 683     }
 684 
 685     if (_collection_set->young_region_length() > 0) {
 686       _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() /
 687                                                         _collection_set->young_region_length());
 688     }
 689 
 690     if (_collection_set->old_region_length() > 0) {
 691       _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() /
 692                                                             _collection_set->old_region_length());
 693     }
 694 
 695     _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms));
 696 
 697     _analytics->report_pending_cards((double) _pending_cards);
 698     _analytics->report_rs_lengths((double) _max_rs_lengths);
 699   }
 700 
 701   collector_state()->set_in_marking_window(new_in_marking_window);
 702   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
 703   _free_regions_at_end_of_collection = _g1->num_free_regions();
 704   // IHOP control wants to know the expected young gen length if it were not
 705   // restrained by the heap reserve. Using the actual length would make the
 706   // prediction too small and the limit the young gen every time we get to the
 707   // predicted target occupancy.
 708   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
 709   update_rs_lengths_prediction();
 710 
 711   update_ihop_prediction(app_time_ms / 1000.0,
 712                          _bytes_allocated_in_old_since_last_gc,
 713                          last_unrestrained_young_length * HeapRegion::GrainBytes);
 714   _bytes_allocated_in_old_since_last_gc = 0;
 715 
 716   _ihop_control->send_trace_event(_g1->gc_tracer_stw());
 717 
 718   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
 719   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
 720 
 721   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
 722     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
 723                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
 724                                 update_rs_time_goal_ms, scan_hcc_time_ms);
 725 
 726     update_rs_time_goal_ms = 0;
 727   } else {
 728     update_rs_time_goal_ms -= scan_hcc_time_ms;
 729   }
 730   _g1->concurrent_g1_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
 731                                       phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
 732                                       update_rs_time_goal_ms);
 733 
 734   cset_chooser()->verify();
 735 }
 736 
 737 G1IHOPControl* G1DefaultPolicy::create_ihop_control(const G1Predictions* predictor){
 738   if (G1UseAdaptiveIHOP) {
 739     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
 740                                      predictor,
 741                                      G1ReservePercent,
 742                                      G1HeapWastePercent);
 743   } else {
 744     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent);
 745   }
 746 }
 747 
 748 void G1DefaultPolicy::update_ihop_prediction(double mutator_time_s,
 749                                       size_t mutator_alloc_bytes,
 750                                       size_t young_gen_size) {
 751   // Always try to update IHOP prediction. Even evacuation failures give information
 752   // about e.g. whether to start IHOP earlier next time.
 753 
 754   // Avoid using really small application times that might create samples with
 755   // very high or very low values. They may be caused by e.g. back-to-back gcs.
 756   double const min_valid_time = 1e-6;
 757 
 758   bool report = false;
 759 
 760   double marking_to_mixed_time = -1.0;
 761   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
 762     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
 763     assert(marking_to_mixed_time > 0.0,
 764            "Initial mark to mixed time must be larger than zero but is %.3f",
 765            marking_to_mixed_time);
 766     if (marking_to_mixed_time > min_valid_time) {
 767       _ihop_control->update_marking_length(marking_to_mixed_time);
 768       report = true;
 769     }
 770   }
 771 
 772   // As an approximation for the young gc promotion rates during marking we use
 773   // all of them. In many applications there are only a few if any young gcs during
 774   // marking, which makes any prediction useless. This increases the accuracy of the
 775   // prediction.
 776   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
 777     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
 778     report = true;
 779   }
 780 
 781   if (report) {
 782     report_ihop_statistics();
 783   }
 784 }
 785 
 786 void G1DefaultPolicy::report_ihop_statistics() {
 787   _ihop_control->print();
 788 }
 789 
 790 void G1DefaultPolicy::print_phases() {
 791   phase_times()->print();
 792 }
 793 
 794 double G1DefaultPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
 795   TruncatedSeq* seq = surv_rate_group->get_seq(age);
 796   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
 797   double pred = _predictor.get_new_prediction(seq);
 798   if (pred > 1.0) {
 799     pred = 1.0;
 800   }
 801   return pred;
 802 }
 803 
 804 double G1DefaultPolicy::accum_yg_surv_rate_pred(int age) const {
 805   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
 806 }
 807 
 808 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
 809                                               size_t scanned_cards) const {
 810   return
 811     _analytics->predict_rs_update_time_ms(pending_cards) +
 812     _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) +
 813     _analytics->predict_constant_other_time_ms();
 814 }
 815 
 816 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
 817   size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();
 818   size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young());
 819   return predict_base_elapsed_time_ms(pending_cards, card_num);
 820 }
 821 
 822 size_t G1DefaultPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
 823   size_t bytes_to_copy;
 824   if (hr->is_marked())
 825     bytes_to_copy = hr->max_live_bytes();
 826   else {
 827     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
 828     int age = hr->age_in_surv_rate_group();
 829     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
 830     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
 831   }
 832   return bytes_to_copy;
 833 }
 834 
 835 double G1DefaultPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
 836                                                 bool for_young_gc) const {
 837   size_t rs_length = hr->rem_set()->occupied();
 838   // Predicting the number of cards is based on which type of GC
 839   // we're predicting for.
 840   size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc);
 841   size_t bytes_to_copy = predict_bytes_to_copy(hr);
 842 
 843   double region_elapsed_time_ms =
 844     _analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) +
 845     _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark());
 846 
 847   // The prediction of the "other" time for this region is based
 848   // upon the region type and NOT the GC type.
 849   if (hr->is_young()) {
 850     region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1);
 851   } else {
 852     region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1);
 853   }
 854   return region_elapsed_time_ms;
 855 }
 856 
 857 bool G1DefaultPolicy::should_allocate_mutator_region() const {
 858   uint young_list_length = _g1->young_regions_count();
 859   uint young_list_target_length = _young_list_target_length;
 860   return young_list_length < young_list_target_length;
 861 }
 862 
 863 bool G1DefaultPolicy::can_expand_young_list() const {
 864   uint young_list_length = _g1->young_regions_count();
 865   uint young_list_max_length = _young_list_max_length;
 866   return young_list_length < young_list_max_length;
 867 }
 868 
 869 bool G1DefaultPolicy::adaptive_young_list_length() const {
 870   return _young_gen_sizer.adaptive_young_list_length();
 871 }
 872 
 873 void G1DefaultPolicy::update_max_gc_locker_expansion() {
 874   uint expansion_region_num = 0;
 875   if (GCLockerEdenExpansionPercent > 0) {
 876     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
 877     double expansion_region_num_d = perc * (double) _young_list_target_length;
 878     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
 879     // less than 1.0) we'll get 1.
 880     expansion_region_num = (uint) ceil(expansion_region_num_d);
 881   } else {
 882     assert(expansion_region_num == 0, "sanity");
 883   }
 884   _young_list_max_length = _young_list_target_length + expansion_region_num;
 885   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
 886 }
 887 
 888 // Calculates survivor space parameters.
 889 void G1DefaultPolicy::update_survivors_policy() {
 890   double max_survivor_regions_d =
 891                  (double) _young_list_target_length / (double) SurvivorRatio;
 892   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
 893   // smaller than 1.0) we'll get 1.
 894   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
 895 
 896   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
 897       HeapRegion::GrainWords * _max_survivor_regions, _policy_counters);
 898 }
 899 
 900 bool G1DefaultPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
 901   // We actually check whether we are marking here and not if we are in a
 902   // reclamation phase. This means that we will schedule a concurrent mark
 903   // even while we are still in the process of reclaiming memory.
 904   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
 905   if (!during_cycle) {
 906     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
 907     collector_state()->set_initiate_conc_mark_if_possible(true);
 908     return true;
 909   } else {
 910     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
 911     return false;
 912   }
 913 }
 914 
 915 void G1DefaultPolicy::initiate_conc_mark() {
 916   collector_state()->set_during_initial_mark_pause(true);
 917   collector_state()->set_initiate_conc_mark_if_possible(false);
 918 }
 919 
 920 void G1DefaultPolicy::decide_on_conc_mark_initiation() {
 921   // We are about to decide on whether this pause will be an
 922   // initial-mark pause.
 923 
 924   // First, collector_state()->during_initial_mark_pause() should not be already set. We
 925   // will set it here if we have to. However, it should be cleared by
 926   // the end of the pause (it's only set for the duration of an
 927   // initial-mark pause).
 928   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
 929 
 930   if (collector_state()->initiate_conc_mark_if_possible()) {
 931     // We had noticed on a previous pause that the heap occupancy has
 932     // gone over the initiating threshold and we should start a
 933     // concurrent marking cycle. So we might initiate one.
 934 
 935     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
 936       // Initiate a new initial mark if there is no marking or reclamation going on.
 937       initiate_conc_mark();
 938       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
 939     } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
 940       // Initiate a user requested initial mark. An initial mark must be young only
 941       // GC, so the collector state must be updated to reflect this.
 942       collector_state()->set_gcs_are_young(true);
 943       collector_state()->set_last_young_gc(false);
 944 
 945       abort_time_to_mixed_tracking();
 946       initiate_conc_mark();
 947       log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
 948     } else {
 949       // The concurrent marking thread is still finishing up the
 950       // previous cycle. If we start one right now the two cycles
 951       // overlap. In particular, the concurrent marking thread might
 952       // be in the process of clearing the next marking bitmap (which
 953       // we will use for the next cycle if we start one). Starting a
 954       // cycle now will be bad given that parts of the marking
 955       // information might get cleared by the marking thread. And we
 956       // cannot wait for the marking thread to finish the cycle as it
 957       // periodically yields while clearing the next marking bitmap
 958       // and, if it's in a yield point, it's waiting for us to
 959       // finish. So, at this point we will not start a cycle and we'll
 960       // let the concurrent marking thread complete the last one.
 961       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
 962     }
 963   }
 964 }
 965 
 966 void G1DefaultPolicy::record_concurrent_mark_cleanup_end() {
 967   cset_chooser()->rebuild(_g1->workers(), _g1->num_regions());
 968 
 969   double end_sec = os::elapsedTime();
 970   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
 971   _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms);
 972   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
 973 
 974   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
 975 }
 976 
 977 double G1DefaultPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
 978   // Returns the given amount of reclaimable bytes (that represents
 979   // the amount of reclaimable space still to be collected) as a
 980   // percentage of the current heap capacity.
 981   size_t capacity_bytes = _g1->capacity();
 982   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
 983 }
 984 
 985 void G1DefaultPolicy::maybe_start_marking() {
 986   if (need_to_start_conc_mark("end of GC")) {
 987     // Note: this might have already been set, if during the last
 988     // pause we decided to start a cycle but at the beginning of
 989     // this pause we decided to postpone it. That's OK.
 990     collector_state()->set_initiate_conc_mark_if_possible(true);
 991   }
 992 }
 993 
 994 G1DefaultPolicy::PauseKind G1DefaultPolicy::young_gc_pause_kind() const {
 995   assert(!collector_state()->full_collection(), "must be");
 996   if (collector_state()->during_initial_mark_pause()) {
 997     assert(collector_state()->last_gc_was_young(), "must be");
 998     assert(!collector_state()->last_young_gc(), "must be");
 999     return InitialMarkGC;
1000   } else if (collector_state()->last_young_gc()) {
1001     assert(!collector_state()->during_initial_mark_pause(), "must be");
1002     assert(collector_state()->last_gc_was_young(), "must be");
1003     return LastYoungGC;
1004   } else if (!collector_state()->last_gc_was_young()) {
1005     assert(!collector_state()->during_initial_mark_pause(), "must be");
1006     assert(!collector_state()->last_young_gc(), "must be");
1007     return MixedGC;
1008   } else {
1009     assert(collector_state()->last_gc_was_young(), "must be");
1010     assert(!collector_state()->during_initial_mark_pause(), "must be");
1011     assert(!collector_state()->last_young_gc(), "must be");
1012     return YoungOnlyGC;
1013   }
1014 }
1015 
1016 void G1DefaultPolicy::record_pause(PauseKind kind, double start, double end) {
1017   // Manage the MMU tracker. For some reason it ignores Full GCs.
1018   if (kind != FullGC) {
1019     _mmu_tracker->add_pause(start, end);
1020   }
1021   // Manage the mutator time tracking from initial mark to first mixed gc.
1022   switch (kind) {
1023     case FullGC:
1024       abort_time_to_mixed_tracking();
1025       break;
1026     case Cleanup:
1027     case Remark:
1028     case YoungOnlyGC:
1029     case LastYoungGC:
1030       _initial_mark_to_mixed.add_pause(end - start);
1031       break;
1032     case InitialMarkGC:
1033       _initial_mark_to_mixed.record_initial_mark_end(end);
1034       break;
1035     case MixedGC:
1036       _initial_mark_to_mixed.record_mixed_gc_start(start);
1037       break;
1038     default:
1039       ShouldNotReachHere();
1040   }
1041 }
1042 
1043 void G1DefaultPolicy::abort_time_to_mixed_tracking() {
1044   _initial_mark_to_mixed.reset();
1045 }
1046 
1047 bool G1DefaultPolicy::next_gc_should_be_mixed(const char* true_action_str,
1048                                        const char* false_action_str) const {
1049   if (cset_chooser()->is_empty()) {
1050     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
1051     return false;
1052   }
1053 
1054   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1055   size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
1056   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1057   double threshold = (double) G1HeapWastePercent;
1058   if (reclaimable_perc <= threshold) {
1059     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1060                         false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1061     return false;
1062   }
1063   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1064                       true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1065   return true;
1066 }
1067 
1068 uint G1DefaultPolicy::calc_min_old_cset_length() const {
1069   // The min old CSet region bound is based on the maximum desired
1070   // number of mixed GCs after a cycle. I.e., even if some old regions
1071   // look expensive, we should add them to the CSet anyway to make
1072   // sure we go through the available old regions in no more than the
1073   // maximum desired number of mixed GCs.
1074   //
1075   // The calculation is based on the number of marked regions we added
1076   // to the CSet chooser in the first place, not how many remain, so
1077   // that the result is the same during all mixed GCs that follow a cycle.
1078 
1079   const size_t region_num = (size_t) cset_chooser()->length();
1080   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1081   size_t result = region_num / gc_num;
1082   // emulate ceiling
1083   if (result * gc_num < region_num) {
1084     result += 1;
1085   }
1086   return (uint) result;
1087 }
1088 
1089 uint G1DefaultPolicy::calc_max_old_cset_length() const {
1090   // The max old CSet region bound is based on the threshold expressed
1091   // as a percentage of the heap size. I.e., it should bound the
1092   // number of old regions added to the CSet irrespective of how many
1093   // of them are available.
1094 
1095   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
1096   const size_t region_num = g1h->num_regions();
1097   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1098   size_t result = region_num * perc / 100;
1099   // emulate ceiling
1100   if (100 * result < region_num * perc) {
1101     result += 1;
1102   }
1103   return (uint) result;
1104 }
1105 
1106 void G1DefaultPolicy::finalize_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {
1107   double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms, survivor);
1108   _collection_set->finalize_old_part(time_remaining_ms);
1109 }
1110 
1111 void G1DefaultPolicy::transfer_survivors_to_cset(const G1SurvivorRegions* survivors) {
1112 
1113   // Add survivor regions to SurvRateGroup.
1114   note_start_adding_survivor_regions();
1115   finished_recalculating_age_indexes(true /* is_survivors */);
1116 
1117   HeapRegion* last = NULL;
1118   for (GrowableArrayIterator<HeapRegion*> it = survivors->regions()->begin();
1119        it != survivors->regions()->end();
1120        ++it) {
1121     HeapRegion* curr = *it;
1122     set_region_survivor(curr);
1123 
1124     // The region is a non-empty survivor so let's add it to
1125     // the incremental collection set for the next evacuation
1126     // pause.
1127     _collection_set->add_survivor_regions(curr);
1128 
1129     last = curr;
1130   }
1131   note_stop_adding_survivor_regions();
1132 
1133   // Don't clear the survivor list handles until the start of
1134   // the next evacuation pause - we need it in order to re-tag
1135   // the survivor regions from this evacuation pause as 'young'
1136   // at the start of the next.
1137 
1138   finished_recalculating_age_indexes(false /* is_survivors */);
1139 }