1 /*

     2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "gc/g1/concurrentMarkThread.inline.hpp"

    27 #include "gc/g1/g1Analytics.hpp"

    28 #include "gc/g1/g1CollectedHeap.inline.hpp"

    29 #include "gc/g1/g1CollectionSet.hpp"

    30 #include "gc/g1/g1ConcurrentMark.hpp"

    31 #include "gc/g1/g1ConcurrentRefine.hpp"

    32 #include "gc/g1/g1DefaultPolicy.hpp"

    33 #include "gc/g1/g1HotCardCache.hpp"

    34 #include "gc/g1/g1IHOPControl.hpp"

    35 #include "gc/g1/g1GCPhaseTimes.hpp"

    36 #include "gc/g1/g1Policy.hpp"

    37 #include "gc/g1/g1SurvivorRegions.hpp"

    38 #include "gc/g1/g1YoungGenSizer.hpp"

    39 #include "gc/g1/heapRegion.inline.hpp"

    40 #include "gc/g1/heapRegionRemSet.hpp"

    41 #include "gc/shared/gcPolicyCounters.hpp"

    42 #include "logging/logStream.hpp"

    43 #include "runtime/arguments.hpp"

    44 #include "runtime/java.hpp"

    45 #include "runtime/mutexLocker.hpp"

    46 #include "utilities/debug.hpp"

    47 #include "utilities/growableArray.hpp"

    48 #include "utilities/pair.hpp"

    49 

    50 G1DefaultPolicy::G1DefaultPolicy(STWGCTimer* gc_timer) :

    51   _predictor(G1ConfidencePercent / 100.0),

    52   _analytics(new G1Analytics(&_predictor)),

    53   _mmu_tracker(new G1MMUTrackerQueue(GCPauseIntervalMillis / 1000.0, MaxGCPauseMillis / 1000.0)),

    54   _ihop_control(create_ihop_control(&_predictor)),

    55   _policy_counters(new GCPolicyCounters("GarbageFirst", 1, 2)),

    56   _young_list_fixed_length(0),

    57   _short_lived_surv_rate_group(new SurvRateGroup()),

    58   _survivor_surv_rate_group(new SurvRateGroup()),

    59   _reserve_factor((double) G1ReservePercent / 100.0),

    60   _reserve_regions(0),

    61   _rs_lengths_prediction(0),

    62   _bytes_allocated_in_old_since_last_gc(0),

    63   _initial_mark_to_mixed(),

    64   _collection_set(NULL),

    65   _g1(NULL),

    66   _phase_times(new G1GCPhaseTimes(gc_timer, ParallelGCThreads)),

    67   _tenuring_threshold(MaxTenuringThreshold),

    68   _max_survivor_regions(0),

    69   _survivors_age_table(true),

    70   _collection_pause_end_millis(os::javaTimeNanos() / NANOSECS_PER_MILLISEC) { }

    71 

    72 G1DefaultPolicy::~G1DefaultPolicy() {

    73   delete _ihop_control;

    74 }

    75 

    76 G1CollectorState* G1DefaultPolicy::collector_state() const { return _g1->collector_state(); }

    77 

    78 void G1DefaultPolicy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) {

    79   _g1 = g1h;

    80   _collection_set = collection_set;

    81 

    82   assert(Heap_lock->owned_by_self(), "Locking discipline.");

    83 

    84   if (!adaptive_young_list_length()) {

    85     _young_list_fixed_length = _young_gen_sizer.min_desired_young_length();

    86   }

    87   _young_gen_sizer.adjust_max_new_size(_g1->max_regions());

    88 

    89   _free_regions_at_end_of_collection = _g1->num_free_regions();

    90 

    91   update_young_list_max_and_target_length();

    92   // We may immediately start allocating regions and placing them on the

    93   // collection set list. Initialize the per-collection set info

    94   _collection_set->start_incremental_building();

    95 }

    96 

    97 void G1DefaultPolicy::note_gc_start() {

    98   phase_times()->note_gc_start();

    99 }

   100 

   101 class G1YoungLengthPredictor VALUE_OBJ_CLASS_SPEC {

   102   const bool _during_cm;

   103   const double _base_time_ms;

   104   const double _base_free_regions;

   105   const double _target_pause_time_ms;

   106   const G1DefaultPolicy* const _policy;

   107 

   108  public:

   109   G1YoungLengthPredictor(bool during_cm,

   110                          double base_time_ms,

   111                          double base_free_regions,

   112                          double target_pause_time_ms,

   113                          const G1DefaultPolicy* policy) :

   114     _during_cm(during_cm),

   115     _base_time_ms(base_time_ms),

   116     _base_free_regions(base_free_regions),

   117     _target_pause_time_ms(target_pause_time_ms),

   118     _policy(policy) {}

   119 

   120   bool will_fit(uint young_length) const {

   121     if (young_length >= _base_free_regions) {

   122       // end condition 1: not enough space for the young regions

   123       return false;

   124     }

   125 

   126     const double accum_surv_rate = _policy->accum_yg_surv_rate_pred((int) young_length - 1);

   127     const size_t bytes_to_copy =

   128                  (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);

   129     const double copy_time_ms =

   130       _policy->analytics()->predict_object_copy_time_ms(bytes_to_copy, _during_cm);

   131     const double young_other_time_ms = _policy->analytics()->predict_young_other_time_ms(young_length);

   132     const double pause_time_ms = _base_time_ms + copy_time_ms + young_other_time_ms;

   133     if (pause_time_ms > _target_pause_time_ms) {

   134       // end condition 2: prediction is over the target pause time

   135       return false;

   136     }

   137 

   138     const size_t free_bytes = (_base_free_regions - young_length) * HeapRegion::GrainBytes;

   139 

   140     // When copying, we will likely need more bytes free than is live in the region.

   141     // Add some safety margin to factor in the confidence of our guess, and the

   142     // natural expected waste.

   143     // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty

   144     // of the calculation: the lower the confidence, the more headroom.

   145     // (100 + TargetPLABWastePct) represents the increase in expected bytes during

   146     // copying due to anticipated waste in the PLABs.

   147     const double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;

   148     const size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);

   149 

   150     if (expected_bytes_to_copy > free_bytes) {

   151       // end condition 3: out-of-space

   152       return false;

   153     }

   154 

   155     // success!

   156     return true;

   157   }

   158 };

   159 

   160 void G1DefaultPolicy::record_new_heap_size(uint new_number_of_regions) {

   161   // re-calculate the necessary reserve

   162   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;

   163   // We use ceiling so that if reserve_regions_d is > 0.0 (but

   164   // smaller than 1.0) we'll get 1.

   165   _reserve_regions = (uint) ceil(reserve_regions_d);

   166 

   167   _young_gen_sizer.heap_size_changed(new_number_of_regions);

   168 

   169   _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes);

   170 }

   171 

   172 uint G1DefaultPolicy::calculate_young_list_desired_min_length(uint base_min_length) const {

   173   uint desired_min_length = 0;

   174   if (adaptive_young_list_length()) {

   175     if (_analytics->num_alloc_rate_ms() > 3) {

   176       double now_sec = os::elapsedTime();

   177       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;

   178       double alloc_rate_ms = _analytics->predict_alloc_rate_ms();

   179       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);

   180     } else {

   181       // otherwise we don't have enough info to make the prediction

   182     }

   183   }

   184   desired_min_length += base_min_length;

   185   // make sure we don't go below any user-defined minimum bound

   186   return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length);

   187 }

   188 

   189 uint G1DefaultPolicy::calculate_young_list_desired_max_length() const {

   190   // Here, we might want to also take into account any additional

   191   // constraints (i.e., user-defined minimum bound). Currently, we

   192   // effectively don't set this bound.

   193   return _young_gen_sizer.max_desired_young_length();

   194 }

   195 

   196 uint G1DefaultPolicy::update_young_list_max_and_target_length() {

   197   return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());

   198 }

   199 

   200 uint G1DefaultPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {

   201   uint unbounded_target_length = update_young_list_target_length(rs_lengths);

   202   update_max_gc_locker_expansion();

   203   return unbounded_target_length;

   204 }

   205 

   206 uint G1DefaultPolicy::update_young_list_target_length(size_t rs_lengths) {

   207   YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);

   208   _young_list_target_length = young_lengths.first;

   209   return young_lengths.second;

   210 }

   211 

   212 G1DefaultPolicy::YoungTargetLengths G1DefaultPolicy::young_list_target_lengths(size_t rs_lengths) const {

   213   YoungTargetLengths result;

   214 

   215   // Calculate the absolute and desired min bounds first.

   216 

   217   // This is how many young regions we already have (currently: the survivors).

   218   const uint base_min_length = _g1->survivor_regions_count();

   219   uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);

   220   // This is the absolute minimum young length. Ensure that we

   221   // will at least have one eden region available for allocation.

   222   uint absolute_min_length = base_min_length + MAX2(_g1->eden_regions_count(), (uint)1);

   223   // If we shrank the young list target it should not shrink below the current size.

   224   desired_min_length = MAX2(desired_min_length, absolute_min_length);

   225   // Calculate the absolute and desired max bounds.

   226 

   227   uint desired_max_length = calculate_young_list_desired_max_length();

   228 

   229   uint young_list_target_length = 0;

   230   if (adaptive_young_list_length()) {

   231     if (collector_state()->gcs_are_young()) {

   232       young_list_target_length =

   233                         calculate_young_list_target_length(rs_lengths,

   234                                                            base_min_length,

   235                                                            desired_min_length,

   236                                                            desired_max_length);

   237     } else {

   238       // Don't calculate anything and let the code below bound it to

   239       // the desired_min_length, i.e., do the next GC as soon as

   240       // possible to maximize how many old regions we can add to it.

   241     }

   242   } else {

   243     // The user asked for a fixed young gen so we'll fix the young gen

   244     // whether the next GC is young or mixed.

   245     young_list_target_length = _young_list_fixed_length;

   246   }

   247 

   248   result.second = young_list_target_length;

   249 

   250   // We will try our best not to "eat" into the reserve.

   251   uint absolute_max_length = 0;

   252   if (_free_regions_at_end_of_collection > _reserve_regions) {

   253     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;

   254   }

   255   if (desired_max_length > absolute_max_length) {

   256     desired_max_length = absolute_max_length;

   257   }

   258 

   259   // Make sure we don't go over the desired max length, nor under the

   260   // desired min length. In case they clash, desired_min_length wins

   261   // which is why that test is second.

   262   if (young_list_target_length > desired_max_length) {

   263     young_list_target_length = desired_max_length;

   264   }

   265   if (young_list_target_length < desired_min_length) {

   266     young_list_target_length = desired_min_length;

   267   }

   268 

   269   assert(young_list_target_length > base_min_length,

   270          "we should be able to allocate at least one eden region");

   271   assert(young_list_target_length >= absolute_min_length, "post-condition");

   272 

   273   result.first = young_list_target_length;

   274   return result;

   275 }

   276 

   277 uint

   278 G1DefaultPolicy::calculate_young_list_target_length(size_t rs_lengths,

   279                                                     uint base_min_length,

   280                                                     uint desired_min_length,

   281                                                     uint desired_max_length) const {

   282   assert(adaptive_young_list_length(), "pre-condition");

   283   assert(collector_state()->gcs_are_young(), "only call this for young GCs");

   284 

   285   // In case some edge-condition makes the desired max length too small...

   286   if (desired_max_length <= desired_min_length) {

   287     return desired_min_length;

   288   }

   289 

   290   // We'll adjust min_young_length and max_young_length not to include

   291   // the already allocated young regions (i.e., so they reflect the

   292   // min and max eden regions we'll allocate). The base_min_length

   293   // will be reflected in the predictions by the

   294   // survivor_regions_evac_time prediction.

   295   assert(desired_min_length > base_min_length, "invariant");

   296   uint min_young_length = desired_min_length - base_min_length;

   297   assert(desired_max_length > base_min_length, "invariant");

   298   uint max_young_length = desired_max_length - base_min_length;

   299 

   300   const double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;

   301   const double survivor_regions_evac_time = predict_survivor_regions_evac_time();

   302   const size_t pending_cards = _analytics->predict_pending_cards();

   303   const size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();

   304   const size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true);

   305   const double base_time_ms =

   306     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +

   307     survivor_regions_evac_time;

   308   const uint available_free_regions = _free_regions_at_end_of_collection;

   309   const uint base_free_regions =

   310     available_free_regions > _reserve_regions ? available_free_regions - _reserve_regions : 0;

   311 

   312   // Here, we will make sure that the shortest young length that

   313   // makes sense fits within the target pause time.

   314 

   315   G1YoungLengthPredictor p(collector_state()->during_concurrent_mark(),

   316                            base_time_ms,

   317                            base_free_regions,

   318                            target_pause_time_ms,

   319                            this);

   320   if (p.will_fit(min_young_length)) {

   321     // The shortest young length will fit into the target pause time;

   322     // we'll now check whether the absolute maximum number of young

   323     // regions will fit in the target pause time. If not, we'll do

   324     // a binary search between min_young_length and max_young_length.

   325     if (p.will_fit(max_young_length)) {

   326       // The maximum young length will fit into the target pause time.

   327       // We are done so set min young length to the maximum length (as

   328       // the result is assumed to be returned in min_young_length).

   329       min_young_length = max_young_length;

   330     } else {

   331       // The maximum possible number of young regions will not fit within

   332       // the target pause time so we'll search for the optimal

   333       // length. The loop invariants are:

   334       //

   335       // min_young_length < max_young_length

   336       // min_young_length is known to fit into the target pause time

   337       // max_young_length is known not to fit into the target pause time

   338       //

   339       // Going into the loop we know the above hold as we've just

   340       // checked them. Every time around the loop we check whether

   341       // the middle value between min_young_length and

   342       // max_young_length fits into the target pause time. If it

   343       // does, it becomes the new min. If it doesn't, it becomes

   344       // the new max. This way we maintain the loop invariants.

   345 

   346       assert(min_young_length < max_young_length, "invariant");

   347       uint diff = (max_young_length - min_young_length) / 2;

   348       while (diff > 0) {

   349         uint young_length = min_young_length + diff;

   350         if (p.will_fit(young_length)) {

   351           min_young_length = young_length;

   352         } else {

   353           max_young_length = young_length;

   354         }

   355         assert(min_young_length <  max_young_length, "invariant");

   356         diff = (max_young_length - min_young_length) / 2;

   357       }

   358       // The results is min_young_length which, according to the

   359       // loop invariants, should fit within the target pause time.

   360 

   361       // These are the post-conditions of the binary search above:

   362       assert(min_young_length < max_young_length,

   363              "otherwise we should have discovered that max_young_length "

   364              "fits into the pause target and not done the binary search");

   365       assert(p.will_fit(min_young_length),

   366              "min_young_length, the result of the binary search, should "

   367              "fit into the pause target");

   368       assert(!p.will_fit(min_young_length + 1),

   369              "min_young_length, the result of the binary search, should be "

   370              "optimal, so no larger length should fit into the pause target");

   371     }

   372   } else {

   373     // Even the minimum length doesn't fit into the pause time

   374     // target, return it as the result nevertheless.

   375   }

   376   return base_min_length + min_young_length;

   377 }

   378 

   379 double G1DefaultPolicy::predict_survivor_regions_evac_time() const {

   380   double survivor_regions_evac_time = 0.0;

   381   const GrowableArray<HeapRegion*>* survivor_regions = _g1->survivor()->regions();

   382 

   383   for (GrowableArrayIterator<HeapRegion*> it = survivor_regions->begin();

   384        it != survivor_regions->end();

   385        ++it) {

   386     survivor_regions_evac_time += predict_region_elapsed_time_ms(*it, collector_state()->gcs_are_young());

   387   }

   388   return survivor_regions_evac_time;

   389 }

   390 

   391 void G1DefaultPolicy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {

   392   guarantee( adaptive_young_list_length(), "should not call this otherwise" );

   393 

   394   if (rs_lengths > _rs_lengths_prediction) {

   395     // add 10% to avoid having to recalculate often

   396     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;

   397     update_rs_lengths_prediction(rs_lengths_prediction);

   398 

   399     update_young_list_max_and_target_length(rs_lengths_prediction);

   400   }

   401 }

   402 

   403 void G1DefaultPolicy::update_rs_lengths_prediction() {

   404   update_rs_lengths_prediction(_analytics->predict_rs_lengths());

   405 }

   406 

   407 void G1DefaultPolicy::update_rs_lengths_prediction(size_t prediction) {

   408   if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {

   409     _rs_lengths_prediction = prediction;

   410   }

   411 }

   412 

   413 void G1DefaultPolicy::record_full_collection_start() {

   414   _full_collection_start_sec = os::elapsedTime();

   415   // Release the future to-space so that it is available for compaction into.

   416   collector_state()->set_full_collection(true);

   417 }

   418 

   419 void G1DefaultPolicy::record_full_collection_end() {

   420   // Consider this like a collection pause for the purposes of allocation

   421   // since last pause.

   422   double end_sec = os::elapsedTime();

   423   double full_gc_time_sec = end_sec - _full_collection_start_sec;

   424   double full_gc_time_ms = full_gc_time_sec * 1000.0;

   425 

   426   _analytics->update_recent_gc_times(end_sec, full_gc_time_ms);

   427 

   428   collector_state()->set_full_collection(false);

   429 

   430   // "Nuke" the heuristics that control the young/mixed GC

   431   // transitions and make sure we start with young GCs after the Full GC.

   432   collector_state()->set_gcs_are_young(true);

   433   collector_state()->set_last_young_gc(false);

   434   collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));

   435   collector_state()->set_during_initial_mark_pause(false);

   436   collector_state()->set_in_marking_window(false);

   437   collector_state()->set_in_marking_window_im(false);

   438 

   439   _short_lived_surv_rate_group->start_adding_regions();

   440   // also call this on any additional surv rate groups

   441 

   442   _free_regions_at_end_of_collection = _g1->num_free_regions();

   443   // Reset survivors SurvRateGroup.

   444   _survivor_surv_rate_group->reset();

   445   update_young_list_max_and_target_length();

   446   update_rs_lengths_prediction();

   447   cset_chooser()->clear();

   448 

   449   _bytes_allocated_in_old_since_last_gc = 0;

   450 

   451   record_pause(FullGC, _full_collection_start_sec, end_sec);

   452 }

   453 

   454 void G1DefaultPolicy::record_collection_pause_start(double start_time_sec) {

   455   // We only need to do this here as the policy will only be applied

   456   // to the GC we're about to start. so, no point is calculating this

   457   // every time we calculate / recalculate the target young length.

   458   update_survivors_policy();

   459 

   460   assert(_g1->used() == _g1->recalculate_used(),

   461          "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,

   462          _g1->used(), _g1->recalculate_used());

   463 

   464   phase_times()->record_cur_collection_start_sec(start_time_sec);

   465   _pending_cards = _g1->pending_card_num();

   466 

   467   _collection_set->reset_bytes_used_before();

   468   _bytes_copied_during_gc = 0;

   469 

   470   collector_state()->set_last_gc_was_young(false);

   471 

   472   // do that for any other surv rate groups

   473   _short_lived_surv_rate_group->stop_adding_regions();

   474   _survivors_age_table.clear();

   475 

   476   assert(_g1->collection_set()->verify_young_ages(), "region age verification failed");

   477 }

   478 

   479 void G1DefaultPolicy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) {

   480   collector_state()->set_during_marking(true);

   481   assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");

   482   collector_state()->set_during_initial_mark_pause(false);

   483 }

   484 

   485 void G1DefaultPolicy::record_concurrent_mark_remark_start() {

   486   _mark_remark_start_sec = os::elapsedTime();

   487   collector_state()->set_during_marking(false);

   488 }

   489 

   490 void G1DefaultPolicy::record_concurrent_mark_remark_end() {

   491   double end_time_sec = os::elapsedTime();

   492   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;

   493   _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms);

   494   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);

   495 

   496   record_pause(Remark, _mark_remark_start_sec, end_time_sec);

   497 }

   498 

   499 void G1DefaultPolicy::record_concurrent_mark_cleanup_start() {

   500   _mark_cleanup_start_sec = os::elapsedTime();

   501 }

   502 

   503 void G1DefaultPolicy::record_concurrent_mark_cleanup_completed() {

   504   bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",

   505                                                               "skip last young-only gc");

   506   collector_state()->set_last_young_gc(should_continue_with_reclaim);

   507   // We skip the marking phase.

   508   if (!should_continue_with_reclaim) {

   509     abort_time_to_mixed_tracking();

   510   }

   511   collector_state()->set_in_marking_window(false);

   512 }

   513 

   514 double G1DefaultPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {

   515   return phase_times()->average_time_ms(phase);

   516 }

   517 

   518 double G1DefaultPolicy::young_other_time_ms() const {

   519   return phase_times()->young_cset_choice_time_ms() +

   520          phase_times()->average_time_ms(G1GCPhaseTimes::YoungFreeCSet);

   521 }

   522 

   523 double G1DefaultPolicy::non_young_other_time_ms() const {

   524   return phase_times()->non_young_cset_choice_time_ms() +

   525          phase_times()->average_time_ms(G1GCPhaseTimes::NonYoungFreeCSet);

   526 }

   527 

   528 double G1DefaultPolicy::other_time_ms(double pause_time_ms) const {

   529   return pause_time_ms - phase_times()->cur_collection_par_time_ms();

   530 }

   531 

   532 double G1DefaultPolicy::constant_other_time_ms(double pause_time_ms) const {

   533   return other_time_ms(pause_time_ms) - phase_times()->total_free_cset_time_ms();

   534 }

   535 

   536 CollectionSetChooser* G1DefaultPolicy::cset_chooser() const {

   537   return _collection_set->cset_chooser();

   538 }

   539 

   540 bool G1DefaultPolicy::about_to_start_mixed_phase() const {

   541   return _g1->concurrent_mark()->cm_thread()->during_cycle() || collector_state()->last_young_gc();

   542 }

   543 

   544 bool G1DefaultPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {

   545   if (about_to_start_mixed_phase()) {

   546     return false;

   547   }

   548 

   549   size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();

   550 

   551   size_t cur_used_bytes = _g1->non_young_capacity_bytes();

   552   size_t alloc_byte_size = alloc_word_size * HeapWordSize;

   553   size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;

   554 

   555   bool result = false;

   556   if (marking_request_bytes > marking_initiating_used_threshold) {

   557     result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();

   558     log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",

   559                               result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",

   560                               cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);

   561   }

   562 

   563   return result;

   564 }

   565 

   566 // Anything below that is considered to be zero

   567 #define MIN_TIMER_GRANULARITY 0.0000001

   568 

   569 void G1DefaultPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {

   570   double end_time_sec = os::elapsedTime();

   571 

   572   size_t cur_used_bytes = _g1->used();

   573   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");

   574   bool last_pause_included_initial_mark = false;

   575   bool update_stats = !_g1->evacuation_failed();

   576 

   577   record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);

   578 

   579   _collection_pause_end_millis = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;

   580 

   581   last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();

   582   if (last_pause_included_initial_mark) {

   583     record_concurrent_mark_init_end(0.0);

   584   } else {

   585     maybe_start_marking();

   586   }

   587 

   588   double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms());

   589   if (app_time_ms < MIN_TIMER_GRANULARITY) {

   590     // This usually happens due to the timer not having the required

   591     // granularity. Some Linuxes are the usual culprits.

   592     // We'll just set it to something (arbitrarily) small.

   593     app_time_ms = 1.0;

   594   }

   595 

   596   if (update_stats) {

   597     // We maintain the invariant that all objects allocated by mutator

   598     // threads will be allocated out of eden regions. So, we can use

   599     // the eden region number allocated since the previous GC to

   600     // calculate the application's allocate rate. The only exception

   601     // to that is humongous objects that are allocated separately. But

   602     // given that humongous object allocations do not really affect

   603     // either the pause's duration nor when the next pause will take

   604     // place we can safely ignore them here.

   605     uint regions_allocated = _collection_set->eden_region_length();

   606     double alloc_rate_ms = (double) regions_allocated / app_time_ms;

   607     _analytics->report_alloc_rate_ms(alloc_rate_ms);

   608 

   609     double interval_ms =

   610       (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0;

   611     _analytics->update_recent_gc_times(end_time_sec, pause_time_ms);

   612     _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms);

   613   }

   614 

   615   bool new_in_marking_window = collector_state()->in_marking_window();

   616   bool new_in_marking_window_im = false;

   617   if (last_pause_included_initial_mark) {

   618     new_in_marking_window = true;

   619     new_in_marking_window_im = true;

   620   }

   621 

   622   if (collector_state()->last_young_gc()) {

   623     // This is supposed to to be the "last young GC" before we start

   624     // doing mixed GCs. Here we decide whether to start mixed GCs or not.

   625     assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");

   626 

   627     if (next_gc_should_be_mixed("start mixed GCs",

   628                                 "do not start mixed GCs")) {

   629       collector_state()->set_gcs_are_young(false);

   630     } else {

   631       // We aborted the mixed GC phase early.

   632       abort_time_to_mixed_tracking();

   633     }

   634 

   635     collector_state()->set_last_young_gc(false);

   636   }

   637 

   638   if (!collector_state()->last_gc_was_young()) {

   639     // This is a mixed GC. Here we decide whether to continue doing

   640     // mixed GCs or not.

   641     if (!next_gc_should_be_mixed("continue mixed GCs",

   642                                  "do not continue mixed GCs")) {

   643       collector_state()->set_gcs_are_young(true);

   644 

   645       maybe_start_marking();

   646     }

   647   }

   648 

   649   _short_lived_surv_rate_group->start_adding_regions();

   650   // Do that for any other surv rate groups

   651 

   652   double scan_hcc_time_ms = G1HotCardCache::default_use_cache() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;

   653 

   654   if (update_stats) {

   655     double cost_per_card_ms = 0.0;

   656     if (_pending_cards > 0) {

   657       cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;

   658       _analytics->report_cost_per_card_ms(cost_per_card_ms);

   659     }

   660     _analytics->report_cost_scan_hcc(scan_hcc_time_ms);

   661 

   662     double cost_per_entry_ms = 0.0;

   663     if (cards_scanned > 10) {

   664       cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;

   665       _analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young());

   666     }

   667 

   668     if (_max_rs_lengths > 0) {

   669       double cards_per_entry_ratio =

   670         (double) cards_scanned / (double) _max_rs_lengths;

   671       _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young());

   672     }

   673 

   674     // This is defensive. For a while _max_rs_lengths could get

   675     // smaller than _recorded_rs_lengths which was causing

   676     // rs_length_diff to get very large and mess up the RSet length

   677     // predictions. The reason was unsafe concurrent updates to the

   678     // _inc_cset_recorded_rs_lengths field which the code below guards

   679     // against (see CR 7118202). This bug has now been fixed (see CR

   680     // 7119027). However, I'm still worried that

   681     // _inc_cset_recorded_rs_lengths might still end up somewhat

   682     // inaccurate. The concurrent refinement thread calculates an

   683     // RSet's length concurrently with other CR threads updating it

   684     // which might cause it to calculate the length incorrectly (if,

   685     // say, it's in mid-coarsening). So I'll leave in the defensive

   686     // conditional below just in case.

   687     size_t rs_length_diff = 0;

   688     size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();

   689     if (_max_rs_lengths > recorded_rs_lengths) {

   690       rs_length_diff = _max_rs_lengths - recorded_rs_lengths;

   691     }

   692     _analytics->report_rs_length_diff((double) rs_length_diff);

   693 

   694     size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;

   695     size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes;

   696     double cost_per_byte_ms = 0.0;

   697 

   698     if (copied_bytes > 0) {

   699       cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;

   700       _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window());

   701     }

   702 

   703     if (_collection_set->young_region_length() > 0) {

   704       _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() /

   705                                                         _collection_set->young_region_length());

   706     }

   707 

   708     if (_collection_set->old_region_length() > 0) {

   709       _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() /

   710                                                             _collection_set->old_region_length());

   711     }

   712 

   713     _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms));

   714 

   715     _analytics->report_pending_cards((double) _pending_cards);

   716     _analytics->report_rs_lengths((double) _max_rs_lengths);

   717   }

   718 

   719   collector_state()->set_in_marking_window(new_in_marking_window);

   720   collector_state()->set_in_marking_window_im(new_in_marking_window_im);

   721   _free_regions_at_end_of_collection = _g1->num_free_regions();

   722   // IHOP control wants to know the expected young gen length if it were not

   723   // restrained by the heap reserve. Using the actual length would make the

   724   // prediction too small and the limit the young gen every time we get to the

   725   // predicted target occupancy.

   726   size_t last_unrestrained_young_length = update_young_list_max_and_target_length();

   727   update_rs_lengths_prediction();

   728 

   729   update_ihop_prediction(app_time_ms / 1000.0,

   730                          _bytes_allocated_in_old_since_last_gc,

   731                          last_unrestrained_young_length * HeapRegion::GrainBytes);

   732   _bytes_allocated_in_old_since_last_gc = 0;

   733 

   734   _ihop_control->send_trace_event(_g1->gc_tracer_stw());

   735 

   736   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.

   737   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;

   738 

   739   if (update_rs_time_goal_ms < scan_hcc_time_ms) {

   740     log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."

   741                                 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms",

   742                                 update_rs_time_goal_ms, scan_hcc_time_ms);

   743 

   744     update_rs_time_goal_ms = 0;

   745   } else {

   746     update_rs_time_goal_ms -= scan_hcc_time_ms;

   747   }

   748   _g1->concurrent_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,

   749                                       phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),

   750                                       update_rs_time_goal_ms);

   751 

   752   cset_chooser()->verify();

   753 }

   754 

   755 G1IHOPControl* G1DefaultPolicy::create_ihop_control(const G1Predictions* predictor){

   756   if (G1UseAdaptiveIHOP) {

   757     return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,

   758                                      predictor,

   759                                      G1ReservePercent,

   760                                      G1HeapWastePercent);

   761   } else {

   762     return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent);

   763   }

   764 }

   765 

   766 void G1DefaultPolicy::update_ihop_prediction(double mutator_time_s,

   767                                       size_t mutator_alloc_bytes,

   768                                       size_t young_gen_size) {

   769   // Always try to update IHOP prediction. Even evacuation failures give information

   770   // about e.g. whether to start IHOP earlier next time.

   771 

   772   // Avoid using really small application times that might create samples with

   773   // very high or very low values. They may be caused by e.g. back-to-back gcs.

   774   double const min_valid_time = 1e-6;

   775 

   776   bool report = false;

   777 

   778   double marking_to_mixed_time = -1.0;

   779   if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {

   780     marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();

   781     assert(marking_to_mixed_time > 0.0,

   782            "Initial mark to mixed time must be larger than zero but is %.3f",

   783            marking_to_mixed_time);

   784     if (marking_to_mixed_time > min_valid_time) {

   785       _ihop_control->update_marking_length(marking_to_mixed_time);

   786       report = true;

   787     }

   788   }

   789 

   790   // As an approximation for the young gc promotion rates during marking we use

   791   // all of them. In many applications there are only a few if any young gcs during

   792   // marking, which makes any prediction useless. This increases the accuracy of the

   793   // prediction.

   794   if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {

   795     _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);

   796     report = true;

   797   }

   798 

   799   if (report) {

   800     report_ihop_statistics();

   801   }

   802 }

   803 

   804 void G1DefaultPolicy::report_ihop_statistics() {

   805   _ihop_control->print();

   806 }

   807 

   808 void G1DefaultPolicy::print_phases() {

   809   phase_times()->print();

   810 }

   811 

   812 double G1DefaultPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {

   813   TruncatedSeq* seq = surv_rate_group->get_seq(age);

   814   guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);

   815   double pred = _predictor.get_new_prediction(seq);

   816   if (pred > 1.0) {

   817     pred = 1.0;

   818   }

   819   return pred;

   820 }

   821 

   822 double G1DefaultPolicy::accum_yg_surv_rate_pred(int age) const {

   823   return _short_lived_surv_rate_group->accum_surv_rate_pred(age);

   824 }

   825 

   826 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards,

   827                                               size_t scanned_cards) const {

   828   return

   829     _analytics->predict_rs_update_time_ms(pending_cards) +

   830     _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) +

   831     _analytics->predict_constant_other_time_ms();

   832 }

   833 

   834 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {

   835   size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();

   836   size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young());

   837   return predict_base_elapsed_time_ms(pending_cards, card_num);

   838 }

   839 

   840 size_t G1DefaultPolicy::predict_bytes_to_copy(HeapRegion* hr) const {

   841   size_t bytes_to_copy;

   842   if (hr->is_marked())

   843     bytes_to_copy = hr->max_live_bytes();

   844   else {

   845     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");

   846     int age = hr->age_in_surv_rate_group();

   847     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());

   848     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);

   849   }

   850   return bytes_to_copy;

   851 }

   852 

   853 double G1DefaultPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,

   854                                                 bool for_young_gc) const {

   855   size_t rs_length = hr->rem_set()->occupied();

   856   // Predicting the number of cards is based on which type of GC

   857   // we're predicting for.

   858   size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc);

   859   size_t bytes_to_copy = predict_bytes_to_copy(hr);

   860 

   861   double region_elapsed_time_ms =

   862     _analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) +

   863     _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark());

   864 

   865   // The prediction of the "other" time for this region is based

   866   // upon the region type and NOT the GC type.

   867   if (hr->is_young()) {

   868     region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1);

   869   } else {

   870     region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1);

   871   }

   872   return region_elapsed_time_ms;

   873 }

   874 

   875 bool G1DefaultPolicy::should_allocate_mutator_region() const {

   876   uint young_list_length = _g1->young_regions_count();

   877   uint young_list_target_length = _young_list_target_length;

   878   return young_list_length < young_list_target_length;

   879 }

   880 

   881 bool G1DefaultPolicy::can_expand_young_list() const {

   882   uint young_list_length = _g1->young_regions_count();

   883   uint young_list_max_length = _young_list_max_length;

   884   return young_list_length < young_list_max_length;

   885 }

   886 

   887 bool G1DefaultPolicy::adaptive_young_list_length() const {

   888   return _young_gen_sizer.adaptive_young_list_length();

   889 }

   890 

   891 size_t G1DefaultPolicy::desired_survivor_size() const {

   892   size_t const survivor_capacity = HeapRegion::GrainWords * _max_survivor_regions;

   893   return (size_t)((((double)survivor_capacity) * TargetSurvivorRatio) / 100);

   894 }

   895 

   896 void G1DefaultPolicy::print_age_table() {

   897   _survivors_age_table.print_age_table(_tenuring_threshold);

   898 }

   899 

   900 void G1DefaultPolicy::update_max_gc_locker_expansion() {

   901   uint expansion_region_num = 0;

   902   if (GCLockerEdenExpansionPercent > 0) {

   903     double perc = (double) GCLockerEdenExpansionPercent / 100.0;

   904     double expansion_region_num_d = perc * (double) _young_list_target_length;

   905     // We use ceiling so that if expansion_region_num_d is > 0.0 (but

   906     // less than 1.0) we'll get 1.

   907     expansion_region_num = (uint) ceil(expansion_region_num_d);

   908   } else {

   909     assert(expansion_region_num == 0, "sanity");

   910   }

   911   _young_list_max_length = _young_list_target_length + expansion_region_num;

   912   assert(_young_list_target_length <= _young_list_max_length, "post-condition");

   913 }

   914 

   915 // Calculates survivor space parameters.

   916 void G1DefaultPolicy::update_survivors_policy() {

   917   double max_survivor_regions_d =

   918                  (double) _young_list_target_length / (double) SurvivorRatio;

   919   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but

   920   // smaller than 1.0) we'll get 1.

   921   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);

   922 

   923   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(desired_survivor_size());

   924   if (UsePerfData) {

   925     _policy_counters->tenuring_threshold()->set_value(_tenuring_threshold);

   926     _policy_counters->desired_survivor_size()->set_value(desired_survivor_size() * oopSize);

   927   }

   928 }

   929 

   930 bool G1DefaultPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {

   931   // We actually check whether we are marking here and not if we are in a

   932   // reclamation phase. This means that we will schedule a concurrent mark

   933   // even while we are still in the process of reclaiming memory.

   934   bool during_cycle = _g1->concurrent_mark()->cm_thread()->during_cycle();

   935   if (!during_cycle) {

   936     log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));

   937     collector_state()->set_initiate_conc_mark_if_possible(true);

   938     return true;

   939   } else {

   940     log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));

   941     return false;

   942   }

   943 }

   944 

   945 void G1DefaultPolicy::initiate_conc_mark() {

   946   collector_state()->set_during_initial_mark_pause(true);

   947   collector_state()->set_initiate_conc_mark_if_possible(false);

   948 }

   949 

   950 void G1DefaultPolicy::decide_on_conc_mark_initiation() {

   951   // We are about to decide on whether this pause will be an

   952   // initial-mark pause.

   953 

   954   // First, collector_state()->during_initial_mark_pause() should not be already set. We

   955   // will set it here if we have to. However, it should be cleared by

   956   // the end of the pause (it's only set for the duration of an

   957   // initial-mark pause).

   958   assert(!collector_state()->during_initial_mark_pause(), "pre-condition");

   959 

   960   if (collector_state()->initiate_conc_mark_if_possible()) {

   961     // We had noticed on a previous pause that the heap occupancy has

   962     // gone over the initiating threshold and we should start a

   963     // concurrent marking cycle. So we might initiate one.

   964 

   965     if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {

   966       // Initiate a new initial mark if there is no marking or reclamation going on.

   967       initiate_conc_mark();

   968       log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");

   969     } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {

   970       // Initiate a user requested initial mark. An initial mark must be young only

   971       // GC, so the collector state must be updated to reflect this.

   972       collector_state()->set_gcs_are_young(true);

   973       collector_state()->set_last_young_gc(false);

   974 

   975       abort_time_to_mixed_tracking();

   976       initiate_conc_mark();

   977       log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");

   978     } else {

   979       // The concurrent marking thread is still finishing up the

   980       // previous cycle. If we start one right now the two cycles

   981       // overlap. In particular, the concurrent marking thread might

   982       // be in the process of clearing the next marking bitmap (which

   983       // we will use for the next cycle if we start one). Starting a

   984       // cycle now will be bad given that parts of the marking

   985       // information might get cleared by the marking thread. And we

   986       // cannot wait for the marking thread to finish the cycle as it

   987       // periodically yields while clearing the next marking bitmap

   988       // and, if it's in a yield point, it's waiting for us to

   989       // finish. So, at this point we will not start a cycle and we'll

   990       // let the concurrent marking thread complete the last one.

   991       log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");

   992     }

   993   }

   994 }

   995 

   996 void G1DefaultPolicy::record_concurrent_mark_cleanup_end() {

   997   cset_chooser()->rebuild(_g1->workers(), _g1->num_regions());

   998 

   999   double end_sec = os::elapsedTime();

  1000   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;

  1001   _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms);

  1002   _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);

  1003 

  1004   record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);

  1005 }

  1006 

  1007 double G1DefaultPolicy::reclaimable_bytes_percent(size_t reclaimable_bytes) const {

  1008   return percent_of(reclaimable_bytes, _g1->capacity());

  1009 }

  1010 

  1011 void G1DefaultPolicy::maybe_start_marking() {

  1012   if (need_to_start_conc_mark("end of GC")) {

  1013     // Note: this might have already been set, if during the last

  1014     // pause we decided to start a cycle but at the beginning of

  1015     // this pause we decided to postpone it. That's OK.

  1016     collector_state()->set_initiate_conc_mark_if_possible(true);

  1017   }

  1018 }

  1019 

  1020 G1DefaultPolicy::PauseKind G1DefaultPolicy::young_gc_pause_kind() const {

  1021   assert(!collector_state()->full_collection(), "must be");

  1022   if (collector_state()->during_initial_mark_pause()) {

  1023     assert(collector_state()->last_gc_was_young(), "must be");

  1024     assert(!collector_state()->last_young_gc(), "must be");

  1025     return InitialMarkGC;

  1026   } else if (collector_state()->last_young_gc()) {

  1027     assert(!collector_state()->during_initial_mark_pause(), "must be");

  1028     assert(collector_state()->last_gc_was_young(), "must be");

  1029     return LastYoungGC;

  1030   } else if (!collector_state()->last_gc_was_young()) {

  1031     assert(!collector_state()->during_initial_mark_pause(), "must be");

  1032     assert(!collector_state()->last_young_gc(), "must be");

  1033     return MixedGC;

  1034   } else {

  1035     assert(collector_state()->last_gc_was_young(), "must be");

  1036     assert(!collector_state()->during_initial_mark_pause(), "must be");

  1037     assert(!collector_state()->last_young_gc(), "must be");

  1038     return YoungOnlyGC;

  1039   }

  1040 }

  1041 

  1042 void G1DefaultPolicy::record_pause(PauseKind kind, double start, double end) {

  1043   // Manage the MMU tracker. For some reason it ignores Full GCs.

  1044   if (kind != FullGC) {

  1045     _mmu_tracker->add_pause(start, end);

  1046   }

  1047   // Manage the mutator time tracking from initial mark to first mixed gc.

  1048   switch (kind) {

  1049     case FullGC:

  1050       abort_time_to_mixed_tracking();

  1051       break;

  1052     case Cleanup:

  1053     case Remark:

  1054     case YoungOnlyGC:

  1055     case LastYoungGC:

  1056       _initial_mark_to_mixed.add_pause(end - start);

  1057       break;

  1058     case InitialMarkGC:

  1059       _initial_mark_to_mixed.record_initial_mark_end(end);

  1060       break;

  1061     case MixedGC:

  1062       _initial_mark_to_mixed.record_mixed_gc_start(start);

  1063       break;

  1064     default:

  1065       ShouldNotReachHere();

  1066   }

  1067 }

  1068 

  1069 void G1DefaultPolicy::abort_time_to_mixed_tracking() {

  1070   _initial_mark_to_mixed.reset();

  1071 }

  1072 

  1073 bool G1DefaultPolicy::next_gc_should_be_mixed(const char* true_action_str,

  1074                                        const char* false_action_str) const {

  1075   if (cset_chooser()->is_empty()) {

  1076     log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);

  1077     return false;

  1078   }

  1079 

  1080   // Is the amount of uncollected reclaimable space above G1HeapWastePercent?

  1081   size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();

  1082   double reclaimable_percent = reclaimable_bytes_percent(reclaimable_bytes);

  1083   double threshold = (double) G1HeapWastePercent;

  1084   if (reclaimable_percent <= threshold) {

  1085     log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,

  1086                         false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent);

  1087     return false;

  1088   }

  1089   log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,

  1090                       true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent);

  1091   return true;

  1092 }

  1093 

  1094 uint G1DefaultPolicy::calc_min_old_cset_length() const {

  1095   // The min old CSet region bound is based on the maximum desired

  1096   // number of mixed GCs after a cycle. I.e., even if some old regions

  1097   // look expensive, we should add them to the CSet anyway to make

  1098   // sure we go through the available old regions in no more than the

  1099   // maximum desired number of mixed GCs.

  1100   //

  1101   // The calculation is based on the number of marked regions we added

  1102   // to the CSet chooser in the first place, not how many remain, so

  1103   // that the result is the same during all mixed GCs that follow a cycle.

  1104 

  1105   const size_t region_num = (size_t) cset_chooser()->length();

  1106   const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);

  1107   size_t result = region_num / gc_num;

  1108   // emulate ceiling

  1109   if (result * gc_num < region_num) {

  1110     result += 1;

  1111   }

  1112   return (uint) result;

  1113 }

  1114 

  1115 uint G1DefaultPolicy::calc_max_old_cset_length() const {

  1116   // The max old CSet region bound is based on the threshold expressed

  1117   // as a percentage of the heap size. I.e., it should bound the

  1118   // number of old regions added to the CSet irrespective of how many

  1119   // of them are available.

  1120 

  1121   const G1CollectedHeap* g1h = G1CollectedHeap::heap();

  1122   const size_t region_num = g1h->num_regions();

  1123   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;

  1124   size_t result = region_num * perc / 100;

  1125   // emulate ceiling

  1126   if (100 * result < region_num * perc) {

  1127     result += 1;

  1128   }

  1129   return (uint) result;

  1130 }

  1131 

  1132 void G1DefaultPolicy::finalize_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {

  1133   double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms, survivor);

  1134   _collection_set->finalize_old_part(time_remaining_ms);

  1135 }