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/g1IHOPControl.hpp"
  33 #include "gc/g1/g1GCPhaseTimes.hpp"
  34 #include "gc/g1/g1Policy.hpp"
  35 #include "gc/g1/g1YoungGenSizer.hpp"
  36 #include "gc/g1/heapRegion.inline.hpp"
  37 #include "gc/g1/heapRegionRemSet.hpp"
  38 #include "gc/shared/gcPolicyCounters.hpp"
  39 #include "runtime/arguments.hpp"
  40 #include "runtime/java.hpp"
  41 #include "runtime/mutexLocker.hpp"
  42 #include "utilities/debug.hpp"
  43 #include "utilities/pair.hpp"
  44 
  45 G1Policy::G1Policy() :
  46   _predictor(G1ConfidencePercent / 100.0),
  47   _analytics(new G1Analytics(&_predictor)),
  48   _pause_time_target_ms((double) MaxGCPauseMillis),
  49   _rs_lengths_prediction(0),
  50   _max_survivor_regions(0),
  51   _survivors_age_table(true),
  52 
  53   _bytes_allocated_in_old_since_last_gc(0),
  54   _ihop_control(NULL),
  55   _policy_counters(new GCPolicyCounters("GarbageFirst", 1, 3)),
  56   _initial_mark_to_mixed() {
  57 
  58   // SurvRateGroups below must be initialized after the predictor because they
  59   // indirectly use it through this object passed to their constructor.
  60   _short_lived_surv_rate_group =
  61     new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary);
  62   _survivor_surv_rate_group =
  63     new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary);
  64 
  65   _phase_times = new G1GCPhaseTimes(ParallelGCThreads);
  66 
  67   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
  68   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
  69   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
  70 
  71   _tenuring_threshold = MaxTenuringThreshold;
  72 
  73 
  74   guarantee(G1ReservePercent <= 50, "Range checking should not allow values over 50.");
  75   _reserve_factor = (double) G1ReservePercent / 100.0;
  76   // This will be set when the heap is expanded
  77   // for the first time during initialization.
  78   _reserve_regions = 0;
  79 
  80   _ihop_control = create_ihop_control();
  81 }
  82 
  83 G1Policy::~G1Policy() {
  84   delete _ihop_control;
  85 }
  86 
  87 G1CollectorState* G1Policy::collector_state() const { return _g1->collector_state(); }
  88 
  89 void G1Policy::init() {
  90   // Set aside an initial future to_space.
  91   _g1 = G1CollectedHeap::heap();
  92   _collection_set = _g1->collection_set();
  93 
  94   assert(Heap_lock->owned_by_self(), "Locking discipline.");
  95 
  96   if (adaptive_young_list_length()) {
  97     _young_list_fixed_length = 0;
  98   } else {
  99     _young_list_fixed_length = _young_gen_sizer.min_desired_young_length();
 100   }
 101   _young_gen_sizer.adjust_max_new_size(_g1->max_regions());
 102 
 103   _free_regions_at_end_of_collection = _g1->num_free_regions();
 104 
 105   update_young_list_max_and_target_length();
 106   // We may immediately start allocating regions and placing them on the
 107   // collection set list. Initialize the per-collection set info
 108   _collection_set->start_incremental_building();
 109 }
 110 
 111 void G1Policy::note_gc_start() {
 112   phase_times()->note_gc_start();
 113 }
 114 
 115 bool G1Policy::predict_will_fit(uint young_length,
 116                                 double base_time_ms,
 117                                 uint base_free_regions,
 118                                 double target_pause_time_ms) const {
 119   if (young_length >= base_free_regions) {
 120     // end condition 1: not enough space for the young regions
 121     return false;
 122   }
 123 
 124   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
 125   size_t bytes_to_copy =
 126                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
 127   double copy_time_ms = _analytics->predict_object_copy_time_ms(bytes_to_copy,
 128                                                                 collector_state()->during_concurrent_mark());
 129   double young_other_time_ms = _analytics->predict_young_other_time_ms(young_length);
 130   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
 131   if (pause_time_ms > target_pause_time_ms) {
 132     // end condition 2: prediction is over the target pause time
 133     return false;
 134   }
 135 
 136   size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
 137 
 138   // When copying, we will likely need more bytes free than is live in the region.
 139   // Add some safety margin to factor in the confidence of our guess, and the
 140   // natural expected waste.
 141   // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
 142   // of the calculation: the lower the confidence, the more headroom.
 143   // (100 + TargetPLABWastePct) represents the increase in expected bytes during
 144   // copying due to anticipated waste in the PLABs.
 145   double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
 146   size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
 147 
 148   if (expected_bytes_to_copy > free_bytes) {
 149     // end condition 3: out-of-space
 150     return false;
 151   }
 152 
 153   // success!
 154   return true;
 155 }
 156 
 157 void G1Policy::record_new_heap_size(uint new_number_of_regions) {
 158   // re-calculate the necessary reserve
 159   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
 160   // We use ceiling so that if reserve_regions_d is > 0.0 (but
 161   // smaller than 1.0) we'll get 1.
 162   _reserve_regions = (uint) ceil(reserve_regions_d);
 163 
 164   _young_gen_sizer.heap_size_changed(new_number_of_regions);
 165 
 166   _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes);
 167 }
 168 
 169 uint G1Policy::calculate_young_list_desired_min_length(uint base_min_length) const {
 170   uint desired_min_length = 0;
 171   if (adaptive_young_list_length()) {
 172     if (_analytics->num_alloc_rate_ms() > 3) {
 173       double now_sec = os::elapsedTime();
 174       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
 175       double alloc_rate_ms = _analytics->predict_alloc_rate_ms();
 176       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
 177     } else {
 178       // otherwise we don't have enough info to make the prediction
 179     }
 180   }
 181   desired_min_length += base_min_length;
 182   // make sure we don't go below any user-defined minimum bound
 183   return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length);
 184 }
 185 
 186 uint G1Policy::calculate_young_list_desired_max_length() const {
 187   // Here, we might want to also take into account any additional
 188   // constraints (i.e., user-defined minimum bound). Currently, we
 189   // effectively don't set this bound.
 190   return _young_gen_sizer.max_desired_young_length();
 191 }
 192 
 193 uint G1Policy::update_young_list_max_and_target_length() {
 194   return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());
 195 }
 196 
 197 uint G1Policy::update_young_list_max_and_target_length(size_t rs_lengths) {
 198   uint unbounded_target_length = update_young_list_target_length(rs_lengths);
 199   update_max_gc_locker_expansion();
 200   return unbounded_target_length;
 201 }
 202 
 203 uint G1Policy::update_young_list_target_length(size_t rs_lengths) {
 204   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
 205   _young_list_target_length = young_lengths.first;
 206   return young_lengths.second;
 207 }
 208 
 209 G1Policy::YoungTargetLengths G1Policy::young_list_target_lengths(size_t rs_lengths) const {
 210   YoungTargetLengths result;
 211 
 212   // Calculate the absolute and desired min bounds first.
 213 
 214   // This is how many young regions we already have (currently: the survivors).
 215   const uint base_min_length = _g1->young_list()->survivor_length();
 216   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
 217   // This is the absolute minimum young length. Ensure that we
 218   // will at least have one eden region available for allocation.
 219   uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
 220   // If we shrank the young list target it should not shrink below the current size.
 221   desired_min_length = MAX2(desired_min_length, absolute_min_length);
 222   // Calculate the absolute and desired max bounds.
 223 
 224   uint desired_max_length = calculate_young_list_desired_max_length();
 225 
 226   uint young_list_target_length = 0;
 227   if (adaptive_young_list_length()) {
 228     if (collector_state()->gcs_are_young()) {
 229       young_list_target_length =
 230                         calculate_young_list_target_length(rs_lengths,
 231                                                            base_min_length,
 232                                                            desired_min_length,
 233                                                            desired_max_length);
 234     } else {
 235       // Don't calculate anything and let the code below bound it to
 236       // the desired_min_length, i.e., do the next GC as soon as
 237       // possible to maximize how many old regions we can add to it.
 238     }
 239   } else {
 240     // The user asked for a fixed young gen so we'll fix the young gen
 241     // whether the next GC is young or mixed.
 242     young_list_target_length = _young_list_fixed_length;
 243   }
 244 
 245   result.second = young_list_target_length;
 246 
 247   // We will try our best not to "eat" into the reserve.
 248   uint absolute_max_length = 0;
 249   if (_free_regions_at_end_of_collection > _reserve_regions) {
 250     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
 251   }
 252   if (desired_max_length > absolute_max_length) {
 253     desired_max_length = absolute_max_length;
 254   }
 255 
 256   // Make sure we don't go over the desired max length, nor under the
 257   // desired min length. In case they clash, desired_min_length wins
 258   // which is why that test is second.
 259   if (young_list_target_length > desired_max_length) {
 260     young_list_target_length = desired_max_length;
 261   }
 262   if (young_list_target_length < desired_min_length) {
 263     young_list_target_length = desired_min_length;
 264   }
 265 
 266   assert(young_list_target_length > base_min_length,
 267          "we should be able to allocate at least one eden region");
 268   assert(young_list_target_length >= absolute_min_length, "post-condition");
 269 
 270   result.first = young_list_target_length;
 271   return result;
 272 }
 273 
 274 uint
 275 G1Policy::calculate_young_list_target_length(size_t rs_lengths,
 276                                              uint base_min_length,
 277                                              uint desired_min_length,
 278                                              uint desired_max_length) const {
 279   assert(adaptive_young_list_length(), "pre-condition");
 280   assert(collector_state()->gcs_are_young(), "only call this for young GCs");
 281 
 282   // In case some edge-condition makes the desired max length too small...
 283   if (desired_max_length <= desired_min_length) {
 284     return desired_min_length;
 285   }
 286 
 287   // We'll adjust min_young_length and max_young_length not to include
 288   // the already allocated young regions (i.e., so they reflect the
 289   // min and max eden regions we'll allocate). The base_min_length
 290   // will be reflected in the predictions by the
 291   // survivor_regions_evac_time prediction.
 292   assert(desired_min_length > base_min_length, "invariant");
 293   uint min_young_length = desired_min_length - base_min_length;
 294   assert(desired_max_length > base_min_length, "invariant");
 295   uint max_young_length = desired_max_length - base_min_length;
 296 
 297   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
 298   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
 299   size_t pending_cards = _analytics->predict_pending_cards();
 300   size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();
 301   size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true);
 302   double base_time_ms =
 303     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
 304     survivor_regions_evac_time;
 305   uint available_free_regions = _free_regions_at_end_of_collection;
 306   uint base_free_regions = 0;
 307   if (available_free_regions > _reserve_regions) {
 308     base_free_regions = available_free_regions - _reserve_regions;
 309   }
 310 
 311   // Here, we will make sure that the shortest young length that
 312   // makes sense fits within the target pause time.
 313 
 314   if (predict_will_fit(min_young_length, base_time_ms,
 315                        base_free_regions, target_pause_time_ms)) {
 316     // The shortest young length will fit into the target pause time;
 317     // we'll now check whether the absolute maximum number of young
 318     // regions will fit in the target pause time. If not, we'll do
 319     // a binary search between min_young_length and max_young_length.
 320     if (predict_will_fit(max_young_length, base_time_ms,
 321                          base_free_regions, target_pause_time_ms)) {
 322       // The maximum young length will fit into the target pause time.
 323       // We are done so set min young length to the maximum length (as
 324       // the result is assumed to be returned in min_young_length).
 325       min_young_length = max_young_length;
 326     } else {
 327       // The maximum possible number of young regions will not fit within
 328       // the target pause time so we'll search for the optimal
 329       // length. The loop invariants are:
 330       //
 331       // min_young_length < max_young_length
 332       // min_young_length is known to fit into the target pause time
 333       // max_young_length is known not to fit into the target pause time
 334       //
 335       // Going into the loop we know the above hold as we've just
 336       // checked them. Every time around the loop we check whether
 337       // the middle value between min_young_length and
 338       // max_young_length fits into the target pause time. If it
 339       // does, it becomes the new min. If it doesn't, it becomes
 340       // the new max. This way we maintain the loop invariants.
 341 
 342       assert(min_young_length < max_young_length, "invariant");
 343       uint diff = (max_young_length - min_young_length) / 2;
 344       while (diff > 0) {
 345         uint young_length = min_young_length + diff;
 346         if (predict_will_fit(young_length, base_time_ms,
 347                              base_free_regions, target_pause_time_ms)) {
 348           min_young_length = young_length;
 349         } else {
 350           max_young_length = young_length;
 351         }
 352         assert(min_young_length <  max_young_length, "invariant");
 353         diff = (max_young_length - min_young_length) / 2;
 354       }
 355       // The results is min_young_length which, according to the
 356       // loop invariants, should fit within the target pause time.
 357 
 358       // These are the post-conditions of the binary search above:
 359       assert(min_young_length < max_young_length,
 360              "otherwise we should have discovered that max_young_length "
 361              "fits into the pause target and not done the binary search");
 362       assert(predict_will_fit(min_young_length, base_time_ms,
 363                               base_free_regions, target_pause_time_ms),
 364              "min_young_length, the result of the binary search, should "
 365              "fit into the pause target");
 366       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
 367                                base_free_regions, target_pause_time_ms),
 368              "min_young_length, the result of the binary search, should be "
 369              "optimal, so no larger length should fit into the pause target");
 370     }
 371   } else {
 372     // Even the minimum length doesn't fit into the pause time
 373     // target, return it as the result nevertheless.
 374   }
 375   return base_min_length + min_young_length;
 376 }
 377 
 378 double G1Policy::predict_survivor_regions_evac_time() const {
 379   double survivor_regions_evac_time = 0.0;
 380   for (HeapRegion * r = _g1->young_list()->first_survivor_region();
 381        r != NULL && r != _g1->young_list()->last_survivor_region()->get_next_young_region();
 382        r = r->get_next_young_region()) {
 383     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
 384   }
 385   return survivor_regions_evac_time;
 386 }
 387 
 388 void G1Policy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {
 389   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
 390 
 391   if (rs_lengths > _rs_lengths_prediction) {
 392     // add 10% to avoid having to recalculate often
 393     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
 394     update_rs_lengths_prediction(rs_lengths_prediction);
 395 
 396     update_young_list_max_and_target_length(rs_lengths_prediction);
 397   }
 398 }
 399 
 400 void G1Policy::update_rs_lengths_prediction() {
 401   update_rs_lengths_prediction(_analytics->predict_rs_lengths());
 402 }
 403 
 404 void G1Policy::update_rs_lengths_prediction(size_t prediction) {
 405   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
 406     _rs_lengths_prediction = prediction;
 407   }
 408 }
 409 
 410 #ifndef PRODUCT
 411 bool G1Policy::verify_young_ages() {
 412   HeapRegion* head = _g1->young_list()->first_region();
 413   return
 414     verify_young_ages(head, _short_lived_surv_rate_group);
 415   // also call verify_young_ages on any additional surv rate groups
 416 }
 417 
 418 bool G1Policy::verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group) {
 419   guarantee( surv_rate_group != NULL, "pre-condition" );
 420 
 421   const char* name = surv_rate_group->name();
 422   bool ret = true;
 423   int prev_age = -1;
 424 
 425   for (HeapRegion* curr = head;
 426        curr != NULL;
 427        curr = curr->get_next_young_region()) {
 428     SurvRateGroup* group = curr->surv_rate_group();
 429     if (group == NULL && !curr->is_survivor()) {
 430       log_error(gc, verify)("## %s: encountered NULL surv_rate_group", name);
 431       ret = false;
 432     }
 433 
 434     if (surv_rate_group == group) {
 435       int age = curr->age_in_surv_rate_group();
 436 
 437       if (age < 0) {
 438         log_error(gc, verify)("## %s: encountered negative age", name);
 439         ret = false;
 440       }
 441 
 442       if (age <= prev_age) {
 443         log_error(gc, verify)("## %s: region ages are not strictly increasing (%d, %d)", name, age, prev_age);
 444         ret = false;
 445       }
 446       prev_age = age;
 447     }
 448   }
 449 
 450   return ret;
 451 }
 452 #endif // PRODUCT
 453 
 454 void G1Policy::record_full_collection_start() {
 455   _full_collection_start_sec = os::elapsedTime();
 456   // Release the future to-space so that it is available for compaction into.
 457   collector_state()->set_full_collection(true);
 458 }
 459 
 460 void G1Policy::record_full_collection_end() {
 461   // Consider this like a collection pause for the purposes of allocation
 462   // since last pause.
 463   double end_sec = os::elapsedTime();
 464   double full_gc_time_sec = end_sec - _full_collection_start_sec;
 465   double full_gc_time_ms = full_gc_time_sec * 1000.0;
 466 
 467   _analytics->update_recent_gc_times(end_sec, full_gc_time_ms);
 468 
 469   collector_state()->set_full_collection(false);
 470 
 471   // "Nuke" the heuristics that control the young/mixed GC
 472   // transitions and make sure we start with young GCs after the Full GC.
 473   collector_state()->set_gcs_are_young(true);
 474   collector_state()->set_last_young_gc(false);
 475   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
 476   collector_state()->set_during_initial_mark_pause(false);
 477   collector_state()->set_in_marking_window(false);
 478   collector_state()->set_in_marking_window_im(false);
 479 
 480   _short_lived_surv_rate_group->start_adding_regions();
 481   // also call this on any additional surv rate groups
 482 
 483   _free_regions_at_end_of_collection = _g1->num_free_regions();
 484   // Reset survivors SurvRateGroup.
 485   _survivor_surv_rate_group->reset();
 486   update_young_list_max_and_target_length();
 487   update_rs_lengths_prediction();
 488   cset_chooser()->clear();
 489 
 490   _bytes_allocated_in_old_since_last_gc = 0;
 491 
 492   record_pause(FullGC, _full_collection_start_sec, end_sec);
 493 }
 494 
 495 void G1Policy::record_collection_pause_start(double start_time_sec) {
 496   // We only need to do this here as the policy will only be applied
 497   // to the GC we're about to start. so, no point is calculating this
 498   // every time we calculate / recalculate the target young length.
 499   update_survivors_policy();
 500 
 501   assert(_g1->used() == _g1->recalculate_used(),
 502          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
 503          _g1->used(), _g1->recalculate_used());
 504 
 505   phase_times()->record_cur_collection_start_sec(start_time_sec);
 506   _pending_cards = _g1->pending_card_num();
 507 
 508   _collection_set->reset_bytes_used_before();
 509   _bytes_copied_during_gc = 0;
 510 
 511   collector_state()->set_last_gc_was_young(false);
 512 
 513   // do that for any other surv rate groups
 514   _short_lived_surv_rate_group->stop_adding_regions();
 515   _survivors_age_table.clear();
 516 
 517   assert( verify_young_ages(), "region age verification" );
 518 }
 519 
 520 void G1Policy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) {
 521   collector_state()->set_during_marking(true);
 522   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
 523   collector_state()->set_during_initial_mark_pause(false);
 524 }
 525 
 526 void G1Policy::record_concurrent_mark_remark_start() {
 527   _mark_remark_start_sec = os::elapsedTime();
 528   collector_state()->set_during_marking(false);
 529 }
 530 
 531 void G1Policy::record_concurrent_mark_remark_end() {
 532   double end_time_sec = os::elapsedTime();
 533   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
 534   _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms);
 535   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
 536 
 537   record_pause(Remark, _mark_remark_start_sec, end_time_sec);
 538 }
 539 
 540 void G1Policy::record_concurrent_mark_cleanup_start() {
 541   _mark_cleanup_start_sec = os::elapsedTime();
 542 }
 543 
 544 void G1Policy::record_concurrent_mark_cleanup_completed() {
 545   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
 546                                                               "skip last young-only gc");
 547   collector_state()->set_last_young_gc(should_continue_with_reclaim);
 548   // We skip the marking phase.
 549   if (!should_continue_with_reclaim) {
 550     abort_time_to_mixed_tracking();
 551   }
 552   collector_state()->set_in_marking_window(false);
 553 }
 554 
 555 double G1Policy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
 556   return phase_times()->average_time_ms(phase);
 557 }
 558 
 559 double G1Policy::young_other_time_ms() const {
 560   return phase_times()->young_cset_choice_time_ms() +
 561          phase_times()->young_free_cset_time_ms();
 562 }
 563 
 564 double G1Policy::non_young_other_time_ms() const {
 565   return phase_times()->non_young_cset_choice_time_ms() +
 566          phase_times()->non_young_free_cset_time_ms();
 567 
 568 }
 569 
 570 double G1Policy::other_time_ms(double pause_time_ms) const {
 571   return pause_time_ms -
 572          average_time_ms(G1GCPhaseTimes::UpdateRS) -
 573          average_time_ms(G1GCPhaseTimes::ScanRS) -
 574          average_time_ms(G1GCPhaseTimes::ObjCopy) -
 575          average_time_ms(G1GCPhaseTimes::Termination);
 576 }
 577 
 578 double G1Policy::constant_other_time_ms(double pause_time_ms) const {
 579   return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
 580 }
 581 
 582 CollectionSetChooser* G1Policy::cset_chooser() const {
 583   return _collection_set->cset_chooser();
 584 }
 585 
 586 bool G1Policy::about_to_start_mixed_phase() const {
 587   return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
 588 }
 589 
 590 bool G1Policy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
 591   if (about_to_start_mixed_phase()) {
 592     return false;
 593   }
 594 
 595   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
 596 
 597   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
 598   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
 599   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
 600 
 601   bool result = false;
 602   if (marking_request_bytes > marking_initiating_used_threshold) {
 603     result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
 604     log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
 605                               result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
 606                               cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
 607   }
 608 
 609   return result;
 610 }
 611 
 612 // Anything below that is considered to be zero
 613 #define MIN_TIMER_GRANULARITY 0.0000001
 614 
 615 void G1Policy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
 616   double end_time_sec = os::elapsedTime();
 617 
 618   size_t cur_used_bytes = _g1->used();
 619   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
 620   bool last_pause_included_initial_mark = false;
 621   bool update_stats = !_g1->evacuation_failed();
 622 
 623   NOT_PRODUCT(_short_lived_surv_rate_group->print());
 624 
 625   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
 626 
 627   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
 628   if (last_pause_included_initial_mark) {
 629     record_concurrent_mark_init_end(0.0);
 630   } else {
 631     maybe_start_marking();
 632   }
 633 
 634   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms());
 635   if (app_time_ms < MIN_TIMER_GRANULARITY) {
 636     // This usually happens due to the timer not having the required
 637     // granularity. Some Linuxes are the usual culprits.
 638     // We'll just set it to something (arbitrarily) small.
 639     app_time_ms = 1.0;
 640   }
 641 
 642   if (update_stats) {
 643     // We maintain the invariant that all objects allocated by mutator
 644     // threads will be allocated out of eden regions. So, we can use
 645     // the eden region number allocated since the previous GC to
 646     // calculate the application's allocate rate. The only exception
 647     // to that is humongous objects that are allocated separately. But
 648     // given that humongous object allocations do not really affect
 649     // either the pause's duration nor when the next pause will take
 650     // place we can safely ignore them here.
 651     uint regions_allocated = _collection_set->eden_region_length();
 652     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
 653     _analytics->report_alloc_rate_ms(alloc_rate_ms);
 654 
 655     double interval_ms =
 656       (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0;
 657     _analytics->update_recent_gc_times(end_time_sec, pause_time_ms);
 658     _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms);
 659   }
 660 
 661   bool new_in_marking_window = collector_state()->in_marking_window();
 662   bool new_in_marking_window_im = false;
 663   if (last_pause_included_initial_mark) {
 664     new_in_marking_window = true;
 665     new_in_marking_window_im = true;
 666   }
 667 
 668   if (collector_state()->last_young_gc()) {
 669     // This is supposed to to be the "last young GC" before we start
 670     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
 671     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
 672 
 673     if (next_gc_should_be_mixed("start mixed GCs",
 674                                 "do not start mixed GCs")) {
 675       collector_state()->set_gcs_are_young(false);
 676     } else {
 677       // We aborted the mixed GC phase early.
 678       abort_time_to_mixed_tracking();
 679     }
 680 
 681     collector_state()->set_last_young_gc(false);
 682   }
 683 
 684   if (!collector_state()->last_gc_was_young()) {
 685     // This is a mixed GC. Here we decide whether to continue doing
 686     // mixed GCs or not.
 687     if (!next_gc_should_be_mixed("continue mixed GCs",
 688                                  "do not continue mixed GCs")) {
 689       collector_state()->set_gcs_are_young(true);
 690 
 691       maybe_start_marking();
 692     }
 693   }
 694 
 695   _short_lived_surv_rate_group->start_adding_regions();
 696   // Do that for any other surv rate groups
 697 
 698   double scan_hcc_time_ms = ConcurrentG1Refine::hot_card_cache_enabled() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;
 699 
 700   if (update_stats) {
 701     double cost_per_card_ms = 0.0;
 702     if (_pending_cards > 0) {
 703       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;
 704       _analytics->report_cost_per_card_ms(cost_per_card_ms);
 705     }
 706     _analytics->report_cost_scan_hcc(scan_hcc_time_ms);
 707 
 708     double cost_per_entry_ms = 0.0;
 709     if (cards_scanned > 10) {
 710       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
 711       _analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young());
 712     }
 713 
 714     if (_max_rs_lengths > 0) {
 715       double cards_per_entry_ratio =
 716         (double) cards_scanned / (double) _max_rs_lengths;
 717       _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young());
 718     }
 719 
 720     // This is defensive. For a while _max_rs_lengths could get
 721     // smaller than _recorded_rs_lengths which was causing
 722     // rs_length_diff to get very large and mess up the RSet length
 723     // predictions. The reason was unsafe concurrent updates to the
 724     // _inc_cset_recorded_rs_lengths field which the code below guards
 725     // against (see CR 7118202). This bug has now been fixed (see CR
 726     // 7119027). However, I'm still worried that
 727     // _inc_cset_recorded_rs_lengths might still end up somewhat
 728     // inaccurate. The concurrent refinement thread calculates an
 729     // RSet's length concurrently with other CR threads updating it
 730     // which might cause it to calculate the length incorrectly (if,
 731     // say, it's in mid-coarsening). So I'll leave in the defensive
 732     // conditional below just in case.
 733     size_t rs_length_diff = 0;
 734     size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();
 735     if (_max_rs_lengths > recorded_rs_lengths) {
 736       rs_length_diff = _max_rs_lengths - recorded_rs_lengths;
 737     }
 738     _analytics->report_rs_length_diff((double) rs_length_diff);
 739 
 740     size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
 741     size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes;
 742     double cost_per_byte_ms = 0.0;
 743 
 744     if (copied_bytes > 0) {
 745       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
 746       _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window());
 747     }
 748 
 749     if (_collection_set->young_region_length() > 0) {
 750       _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() /
 751                                                         _collection_set->young_region_length());
 752     }
 753 
 754     if (_collection_set->old_region_length() > 0) {
 755       _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() /
 756                                                             _collection_set->old_region_length());
 757     }
 758 
 759     _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms));
 760 
 761     _analytics->report_pending_cards((double) _pending_cards);
 762     _analytics->report_rs_lengths((double) _max_rs_lengths);
 763   }
 764 
 765   collector_state()->set_in_marking_window(new_in_marking_window);
 766   collector_state()->set_in_marking_window_im(new_in_marking_window_im);
 767   _free_regions_at_end_of_collection = _g1->num_free_regions();
 768   // IHOP control wants to know the expected young gen length if it were not
 769   // restrained by the heap reserve. Using the actual length would make the
 770   // prediction too small and the limit the young gen every time we get to the
 771   // predicted target occupancy.
 772   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
 773   update_rs_lengths_prediction();
 774 
 775   update_ihop_prediction(app_time_ms / 1000.0,
 776                          _bytes_allocated_in_old_since_last_gc,
 777                          last_unrestrained_young_length * HeapRegion::GrainBytes);
 778   _bytes_allocated_in_old_since_last_gc = 0;
 779 
 780   _ihop_control->send_trace_event(_g1->gc_tracer_stw());
 781 
 782   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
 783   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
 784 
 785   if (update_rs_time_goal_ms < scan_hcc_time_ms) {
 786     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
 787                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
 788                                 update_rs_time_goal_ms, scan_hcc_time_ms);
 789 
 790     update_rs_time_goal_ms = 0;
 791   } else {
 792     update_rs_time_goal_ms -= scan_hcc_time_ms;
 793   }
 794   _g1->concurrent_g1_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
 795                                       phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
 796                                       update_rs_time_goal_ms);
 797 
 798   cset_chooser()->verify();
 799 }
 800 
 801 G1IHOPControl* G1Policy::create_ihop_control() const {
 802   if (G1UseAdaptiveIHOP) {
 803     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
 804                                      &_predictor,
 805                                      G1ReservePercent,
 806                                      G1HeapWastePercent);
 807   } else {
 808     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent);
 809   }
 810 }
 811 
 812 void G1Policy::update_ihop_prediction(double mutator_time_s,
 813                                       size_t mutator_alloc_bytes,
 814                                       size_t young_gen_size) {
 815   // Always try to update IHOP prediction. Even evacuation failures give information
 816   // about e.g. whether to start IHOP earlier next time.
 817 
 818   // Avoid using really small application times that might create samples with
 819   // very high or very low values. They may be caused by e.g. back-to-back gcs.
 820   double const min_valid_time = 1e-6;
 821 
 822   bool report = false;
 823 
 824   double marking_to_mixed_time = -1.0;
 825   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
 826     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
 827     assert(marking_to_mixed_time > 0.0,
 828            "Initial mark to mixed time must be larger than zero but is %.3f",
 829            marking_to_mixed_time);
 830     if (marking_to_mixed_time > min_valid_time) {
 831       _ihop_control->update_marking_length(marking_to_mixed_time);
 832       report = true;
 833     }
 834   }
 835 
 836   // As an approximation for the young gc promotion rates during marking we use
 837   // all of them. In many applications there are only a few if any young gcs during
 838   // marking, which makes any prediction useless. This increases the accuracy of the
 839   // prediction.
 840   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
 841     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
 842     report = true;
 843   }
 844 
 845   if (report) {
 846     report_ihop_statistics();
 847   }
 848 }
 849 
 850 void G1Policy::report_ihop_statistics() {
 851   _ihop_control->print();
 852 }
 853 
 854 void G1Policy::print_phases() {
 855   phase_times()->print();
 856 }
 857 
 858 double G1Policy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
 859   TruncatedSeq* seq = surv_rate_group->get_seq(age);
 860   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
 861   double pred = _predictor.get_new_prediction(seq);
 862   if (pred > 1.0) {
 863     pred = 1.0;
 864   }
 865   return pred;
 866 }
 867 
 868 double G1Policy::predict_yg_surv_rate(int age) const {
 869   return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
 870 }
 871 
 872 double G1Policy::accum_yg_surv_rate_pred(int age) const {
 873   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
 874 }
 875 
 876 double G1Policy::predict_base_elapsed_time_ms(size_t pending_cards,
 877                                               size_t scanned_cards) const {
 878   return
 879     _analytics->predict_rs_update_time_ms(pending_cards) +
 880     _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) +
 881     _analytics->predict_constant_other_time_ms();
 882 }
 883 
 884 double G1Policy::predict_base_elapsed_time_ms(size_t pending_cards) const {
 885   size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();
 886   size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young());
 887   return predict_base_elapsed_time_ms(pending_cards, card_num);
 888 }
 889 
 890 size_t G1Policy::predict_bytes_to_copy(HeapRegion* hr) const {
 891   size_t bytes_to_copy;
 892   if (hr->is_marked())
 893     bytes_to_copy = hr->max_live_bytes();
 894   else {
 895     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
 896     int age = hr->age_in_surv_rate_group();
 897     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
 898     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
 899   }
 900   return bytes_to_copy;
 901 }
 902 
 903 double G1Policy::predict_region_elapsed_time_ms(HeapRegion* hr,
 904                                                 bool for_young_gc) const {
 905   size_t rs_length = hr->rem_set()->occupied();
 906   // Predicting the number of cards is based on which type of GC
 907   // we're predicting for.
 908   size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc);
 909   size_t bytes_to_copy = predict_bytes_to_copy(hr);
 910 
 911   double region_elapsed_time_ms =
 912     _analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) +
 913     _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark());
 914 
 915   // The prediction of the "other" time for this region is based
 916   // upon the region type and NOT the GC type.
 917   if (hr->is_young()) {
 918     region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1);
 919   } else {
 920     region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1);
 921   }
 922   return region_elapsed_time_ms;
 923 }
 924 
 925 
 926 void G1Policy::print_yg_surv_rate_info() const {
 927 #ifndef PRODUCT
 928   _short_lived_surv_rate_group->print_surv_rate_summary();
 929   // add this call for any other surv rate groups
 930 #endif // PRODUCT
 931 }
 932 
 933 bool G1Policy::is_young_list_full() const {
 934   uint young_list_length = _g1->young_list()->length();
 935   uint young_list_target_length = _young_list_target_length;
 936   return young_list_length >= young_list_target_length;
 937 }
 938 
 939 bool G1Policy::can_expand_young_list() const {
 940   uint young_list_length = _g1->young_list()->length();
 941   uint young_list_max_length = _young_list_max_length;
 942   return young_list_length < young_list_max_length;
 943 }
 944 
 945 bool G1Policy::adaptive_young_list_length() const {
 946   return _young_gen_sizer.adaptive_young_list_length();
 947 }
 948 
 949 void G1Policy::update_max_gc_locker_expansion() {
 950   uint expansion_region_num = 0;
 951   if (GCLockerEdenExpansionPercent > 0) {
 952     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
 953     double expansion_region_num_d = perc * (double) _young_list_target_length;
 954     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
 955     // less than 1.0) we'll get 1.
 956     expansion_region_num = (uint) ceil(expansion_region_num_d);
 957   } else {
 958     assert(expansion_region_num == 0, "sanity");
 959   }
 960   _young_list_max_length = _young_list_target_length + expansion_region_num;
 961   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
 962 }
 963 
 964 // Calculates survivor space parameters.
 965 void G1Policy::update_survivors_policy() {
 966   double max_survivor_regions_d =
 967                  (double) _young_list_target_length / (double) SurvivorRatio;
 968   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
 969   // smaller than 1.0) we'll get 1.
 970   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
 971 
 972   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
 973       HeapRegion::GrainWords * _max_survivor_regions, _policy_counters);
 974 }
 975 
 976 bool G1Policy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
 977   // We actually check whether we are marking here and not if we are in a
 978   // reclamation phase. This means that we will schedule a concurrent mark
 979   // even while we are still in the process of reclaiming memory.
 980   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
 981   if (!during_cycle) {
 982     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
 983     collector_state()->set_initiate_conc_mark_if_possible(true);
 984     return true;
 985   } else {
 986     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
 987     return false;
 988   }
 989 }
 990 
 991 void G1Policy::initiate_conc_mark() {
 992   collector_state()->set_during_initial_mark_pause(true);
 993   collector_state()->set_initiate_conc_mark_if_possible(false);
 994 }
 995 
 996 void G1Policy::decide_on_conc_mark_initiation() {
 997   // We are about to decide on whether this pause will be an
 998   // initial-mark pause.
 999 
1000   // First, collector_state()->during_initial_mark_pause() should not be already set. We
1001   // will set it here if we have to. However, it should be cleared by
1002   // the end of the pause (it's only set for the duration of an
1003   // initial-mark pause).
1004   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
1005 
1006   if (collector_state()->initiate_conc_mark_if_possible()) {
1007     // We had noticed on a previous pause that the heap occupancy has
1008     // gone over the initiating threshold and we should start a
1009     // concurrent marking cycle. So we might initiate one.
1010 
1011     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
1012       // Initiate a new initial mark if there is no marking or reclamation going on.
1013       initiate_conc_mark();
1014       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
1015     } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
1016       // Initiate a user requested initial mark. An initial mark must be young only
1017       // GC, so the collector state must be updated to reflect this.
1018       collector_state()->set_gcs_are_young(true);
1019       collector_state()->set_last_young_gc(false);
1020 
1021       abort_time_to_mixed_tracking();
1022       initiate_conc_mark();
1023       log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
1024     } else {
1025       // The concurrent marking thread is still finishing up the
1026       // previous cycle. If we start one right now the two cycles
1027       // overlap. In particular, the concurrent marking thread might
1028       // be in the process of clearing the next marking bitmap (which
1029       // we will use for the next cycle if we start one). Starting a
1030       // cycle now will be bad given that parts of the marking
1031       // information might get cleared by the marking thread. And we
1032       // cannot wait for the marking thread to finish the cycle as it
1033       // periodically yields while clearing the next marking bitmap
1034       // and, if it's in a yield point, it's waiting for us to
1035       // finish. So, at this point we will not start a cycle and we'll
1036       // let the concurrent marking thread complete the last one.
1037       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
1038     }
1039   }
1040 }
1041 
1042 void G1Policy::record_concurrent_mark_cleanup_end() {
1043   cset_chooser()->rebuild(_g1->workers(), _g1->num_regions());
1044 
1045   double end_sec = os::elapsedTime();
1046   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
1047   _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms);
1048   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
1049 
1050   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
1051 }
1052 
1053 double G1Policy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
1054   // Returns the given amount of reclaimable bytes (that represents
1055   // the amount of reclaimable space still to be collected) as a
1056   // percentage of the current heap capacity.
1057   size_t capacity_bytes = _g1->capacity();
1058   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1059 }
1060 
1061 void G1Policy::maybe_start_marking() {
1062   if (need_to_start_conc_mark("end of GC")) {
1063     // Note: this might have already been set, if during the last
1064     // pause we decided to start a cycle but at the beginning of
1065     // this pause we decided to postpone it. That's OK.
1066     collector_state()->set_initiate_conc_mark_if_possible(true);
1067   }
1068 }
1069 
1070 G1Policy::PauseKind G1Policy::young_gc_pause_kind() const {
1071   assert(!collector_state()->full_collection(), "must be");
1072   if (collector_state()->during_initial_mark_pause()) {
1073     assert(collector_state()->last_gc_was_young(), "must be");
1074     assert(!collector_state()->last_young_gc(), "must be");
1075     return InitialMarkGC;
1076   } else if (collector_state()->last_young_gc()) {
1077     assert(!collector_state()->during_initial_mark_pause(), "must be");
1078     assert(collector_state()->last_gc_was_young(), "must be");
1079     return LastYoungGC;
1080   } else if (!collector_state()->last_gc_was_young()) {
1081     assert(!collector_state()->during_initial_mark_pause(), "must be");
1082     assert(!collector_state()->last_young_gc(), "must be");
1083     return MixedGC;
1084   } else {
1085     assert(collector_state()->last_gc_was_young(), "must be");
1086     assert(!collector_state()->during_initial_mark_pause(), "must be");
1087     assert(!collector_state()->last_young_gc(), "must be");
1088     return YoungOnlyGC;
1089   }
1090 }
1091 
1092 void G1Policy::record_pause(PauseKind kind, double start, double end) {
1093   // Manage the MMU tracker. For some reason it ignores Full GCs.
1094   if (kind != FullGC) {
1095     _mmu_tracker->add_pause(start, end);
1096   }
1097   // Manage the mutator time tracking from initial mark to first mixed gc.
1098   switch (kind) {
1099     case FullGC:
1100       abort_time_to_mixed_tracking();
1101       break;
1102     case Cleanup:
1103     case Remark:
1104     case YoungOnlyGC:
1105     case LastYoungGC:
1106       _initial_mark_to_mixed.add_pause(end - start);
1107       break;
1108     case InitialMarkGC:
1109       _initial_mark_to_mixed.record_initial_mark_end(end);
1110       break;
1111     case MixedGC:
1112       _initial_mark_to_mixed.record_mixed_gc_start(start);
1113       break;
1114     default:
1115       ShouldNotReachHere();
1116   }
1117 }
1118 
1119 void G1Policy::abort_time_to_mixed_tracking() {
1120   _initial_mark_to_mixed.reset();
1121 }
1122 
1123 bool G1Policy::next_gc_should_be_mixed(const char* true_action_str,
1124                                        const char* false_action_str) const {
1125   if (cset_chooser()->is_empty()) {
1126     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
1127     return false;
1128   }
1129 
1130   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1131   size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
1132   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1133   double threshold = (double) G1HeapWastePercent;
1134   if (reclaimable_perc <= threshold) {
1135     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1136                         false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1137     return false;
1138   }
1139   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
1140                       true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
1141   return true;
1142 }
1143 
1144 uint G1Policy::calc_min_old_cset_length() const {
1145   // The min old CSet region bound is based on the maximum desired
1146   // number of mixed GCs after a cycle. I.e., even if some old regions
1147   // look expensive, we should add them to the CSet anyway to make
1148   // sure we go through the available old regions in no more than the
1149   // maximum desired number of mixed GCs.
1150   //
1151   // The calculation is based on the number of marked regions we added
1152   // to the CSet chooser in the first place, not how many remain, so
1153   // that the result is the same during all mixed GCs that follow a cycle.
1154 
1155   const size_t region_num = (size_t) cset_chooser()->length();
1156   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1157   size_t result = region_num / gc_num;
1158   // emulate ceiling
1159   if (result * gc_num < region_num) {
1160     result += 1;
1161   }
1162   return (uint) result;
1163 }
1164 
1165 uint G1Policy::calc_max_old_cset_length() const {
1166   // The max old CSet region bound is based on the threshold expressed
1167   // as a percentage of the heap size. I.e., it should bound the
1168   // number of old regions added to the CSet irrespective of how many
1169   // of them are available.
1170 
1171   const G1CollectedHeap* g1h = G1CollectedHeap::heap();
1172   const size_t region_num = g1h->num_regions();
1173   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1174   size_t result = region_num * perc / 100;
1175   // emulate ceiling
1176   if (100 * result < region_num * perc) {
1177     result += 1;
1178   }
1179   return (uint) result;
1180 }
1181 
1182 void G1Policy::finalize_collection_set(double target_pause_time_ms) {
1183   double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms);
1184   _collection_set->finalize_old_part(time_remaining_ms);
1185 }