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 /*

  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.

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

  *

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

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

  * published by the Free Software Foundation.

  *

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

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

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

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

  * accompanied this code).

  *

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

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

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

  *

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

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

  * questions.

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  */

 #ifndef __clang_major__

 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.

 #endif

 #include "precompiled.hpp"

 #include "gc_implementation/g1/concurrentG1Refine.hpp"

 #include "gc_implementation/g1/concurrentMark.hpp"

 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1CollectorPolicy.hpp"

 #include "gc_implementation/g1/g1ErgoVerbose.hpp"

 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"

 #include "gc_implementation/g1/g1Log.hpp"

 #include "gc_implementation/g1/heapRegionRemSet.hpp"

 #include "gc_implementation/shared/gcPolicyCounters.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/java.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "utilities/debug.hpp"

 // Different defaults for different number of GC threads

 // They were chosen by running GCOld and SPECjbb on debris with different

 //   numbers of GC threads and choosing them based on the results

 // all the same

 static double rs_length_diff_defaults[] = {

   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0

 };

 static double cost_per_card_ms_defaults[] = {

   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015

 };

 // all the same

 static double young_cards_per_entry_ratio_defaults[] = {

   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0

 };

 static double cost_per_entry_ms_defaults[] = {

   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005

 };

 static double cost_per_byte_ms_defaults[] = {

   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009

 };

 // these should be pretty consistent

 static double constant_other_time_ms_defaults[] = {

   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0

 };

 static double young_other_cost_per_region_ms_defaults[] = {

   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1

 };

 static double non_young_other_cost_per_region_ms_defaults[] = {

   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30

 };

 G1CollectorPolicy::G1CollectorPolicy() :

   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()

                         ? ParallelGCThreads : 1),

   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _stop_world_start(0.0),

   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _prev_collection_pause_end_ms(0.0),

   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),

   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),

   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _non_young_other_cost_per_region_ms_seq(

                                          new TruncatedSeq(TruncatedSeqLength)),

   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),

   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),

   _pause_time_target_ms((double) MaxGCPauseMillis),

   _gcs_are_young(true),

   _during_marking(false),

   _in_marking_window(false),

   _in_marking_window_im(false),

   _recent_prev_end_times_for_all_gcs_sec(

                                 new TruncatedSeq(NumPrevPausesForHeuristics)),

   _recent_avg_pause_time_ratio(0.0),

   _initiate_conc_mark_if_possible(false),

   _during_initial_mark_pause(false),

   _last_young_gc(false),

   _last_gc_was_young(false),

   _eden_used_bytes_before_gc(0),

   _survivor_used_bytes_before_gc(0),

   _heap_used_bytes_before_gc(0),

   _metaspace_used_bytes_before_gc(0),

   _eden_capacity_bytes_before_gc(0),

   _heap_capacity_bytes_before_gc(0),

   _eden_cset_region_length(0),

   _survivor_cset_region_length(0),

   _old_cset_region_length(0),

   _collection_set(NULL),

   _collection_set_bytes_used_before(0),

   // Incremental CSet attributes

   _inc_cset_build_state(Inactive),

   _inc_cset_head(NULL),

   _inc_cset_tail(NULL),

   _inc_cset_bytes_used_before(0),

   _inc_cset_max_finger(NULL),

   _inc_cset_recorded_rs_lengths(0),

   _inc_cset_recorded_rs_lengths_diffs(0),

   _inc_cset_predicted_elapsed_time_ms(0.0),

   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),

 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away

 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list

 #endif // _MSC_VER

   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",

                                                  G1YoungSurvRateNumRegionsSummary)),

   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",

                                               G1YoungSurvRateNumRegionsSummary)),

   // add here any more surv rate groups

   _recorded_survivor_regions(0),

   _recorded_survivor_head(NULL),

   _recorded_survivor_tail(NULL),

   _survivors_age_table(true),

   _gc_overhead_perc(0.0) {

   // Set up the region size and associated fields. Given that the

   // policy is created before the heap, we have to set this up here,

   // so it's done as soon as possible.

   // It would have been natural to pass initial_heap_byte_size() and

   // max_heap_byte_size() to setup_heap_region_size() but those have

   // not been set up at this point since they should be aligned with

   // the region size. So, there is a circular dependency here. We base

   // the region size on the heap size, but the heap size should be

   // aligned with the region size. To get around this we use the

   // unaligned values for the heap.

   HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);

   HeapRegionRemSet::setup_remset_size();

   G1ErgoVerbose::initialize();

   if (PrintAdaptiveSizePolicy) {

     // Currently, we only use a single switch for all the heuristics.

     G1ErgoVerbose::set_enabled(true);

     // Given that we don't currently have a verboseness level

     // parameter, we'll hardcode this to high. This can be easily

     // changed in the future.

     G1ErgoVerbose::set_level(ErgoHigh);

   } else {

     G1ErgoVerbose::set_enabled(false);

   }

   // Verify PLAB sizes

   const size_t region_size = HeapRegion::GrainWords;

   if (YoungPLABSize > region_size || OldPLABSize > region_size) {

     char buffer[128];

     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,

                  OldPLABSize > region_size ? "Old" : "Young", region_size);

     vm_exit_during_initialization(buffer);

   }

   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());

   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;

   _phase_times = new G1GCPhaseTimes(_parallel_gc_threads);

   int index = MIN2(_parallel_gc_threads - 1, 7);

   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);

   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);

   _young_cards_per_entry_ratio_seq->add(

                                   young_cards_per_entry_ratio_defaults[index]);

   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);

   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);

   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);

   _young_other_cost_per_region_ms_seq->add(

                                young_other_cost_per_region_ms_defaults[index]);

   _non_young_other_cost_per_region_ms_seq->add(

                            non_young_other_cost_per_region_ms_defaults[index]);

   // Below, we might need to calculate the pause time target based on

   // the pause interval. When we do so we are going to give G1 maximum

   // flexibility and allow it to do pauses when it needs to. So, we'll

   // arrange that the pause interval to be pause time target + 1 to

   // ensure that a) the pause time target is maximized with respect to

   // the pause interval and b) we maintain the invariant that pause

   // time target < pause interval. If the user does not want this

   // maximum flexibility, they will have to set the pause interval

   // explicitly.

   // First make sure that, if either parameter is set, its value is

   // reasonable.

   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {

     if (MaxGCPauseMillis < 1) {

       vm_exit_during_initialization("MaxGCPauseMillis should be "

                                     "greater than 0");

     }

   }

   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

     if (GCPauseIntervalMillis < 1) {

       vm_exit_during_initialization("GCPauseIntervalMillis should be "

                                     "greater than 0");

     }

   }

   // Then, if the pause time target parameter was not set, set it to

   // the default value.

   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {

     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

       // The default pause time target in G1 is 200ms

       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);

     } else {

       // We do not allow the pause interval to be set without the

       // pause time target

       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "

                                     "without setting MaxGCPauseMillis");

     }

   }

   // Then, if the interval parameter was not set, set it according to

   // the pause time target (this will also deal with the case when the

   // pause time target is the default value).

   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);

   }

   // Finally, make sure that the two parameters are consistent.

   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {

     char buffer[256];

     jio_snprintf(buffer, 256,

                  "MaxGCPauseMillis (%u) should be less than "

                  "GCPauseIntervalMillis (%u)",

                  MaxGCPauseMillis, GCPauseIntervalMillis);

     vm_exit_during_initialization(buffer);

   }

   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;

   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;

   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);

   uintx confidence_perc = G1ConfidencePercent;

   // Put an artificial ceiling on this so that it's not set to a silly value.

   if (confidence_perc > 100) {

     confidence_perc = 100;

     warning("G1ConfidencePercent is set to a value that is too large, "

             "it's been updated to %u", confidence_perc);

   }

   _sigma = (double) confidence_perc / 100.0;

   // start conservatively (around 50ms is about right)

   _concurrent_mark_remark_times_ms->add(0.05);

   _concurrent_mark_cleanup_times_ms->add(0.20);

   _tenuring_threshold = MaxTenuringThreshold;

   // _max_survivor_regions will be calculated by

   // update_young_list_target_length() during initialization.

   _max_survivor_regions = 0;

   assert(GCTimeRatio > 0,

          "we should have set it to a default value set_g1_gc_flags() "

          "if a user set it to 0");

   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));

   uintx reserve_perc = G1ReservePercent;

   // Put an artificial ceiling on this so that it's not set to a silly value.

   if (reserve_perc > 50) {

     reserve_perc = 50;

     warning("G1ReservePercent is set to a value that is too large, "

             "it's been updated to %u", reserve_perc);

   }

   _reserve_factor = (double) reserve_perc / 100.0;

   // This will be set when the heap is expanded

   // for the first time during initialization.

   _reserve_regions = 0;

   _collectionSetChooser = new CollectionSetChooser();

 }

 void G1CollectorPolicy::initialize_alignments() {

   _space_alignment = HeapRegion::GrainBytes;

   size_t card_table_alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);

   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();

   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);

 }

 void G1CollectorPolicy::initialize_flags() {

   if (G1HeapRegionSize != HeapRegion::GrainBytes) {

     FLAG_SET_ERGO(uintx, G1HeapRegionSize, HeapRegion::GrainBytes);

   }

   if (SurvivorRatio < 1) {

     vm_exit_during_initialization("Invalid survivor ratio specified");

   }

   CollectorPolicy::initialize_flags();

   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags

 }

 void G1CollectorPolicy::post_heap_initialize() {

   uintx max_regions = G1CollectedHeap::heap()->max_regions();

   size_t max_young_size = (size_t)_young_gen_sizer->max_young_length(max_regions) * HeapRegion::GrainBytes;

   if (max_young_size != MaxNewSize) {

     FLAG_SET_ERGO(uintx, MaxNewSize, max_young_size);

   }

 }

 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true),

         _min_desired_young_length(0), _max_desired_young_length(0) {

   if (FLAG_IS_CMDLINE(NewRatio)) {

     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {

       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");

     } else {

       _sizer_kind = SizerNewRatio;

       _adaptive_size = false;

       return;

     }

   }

   if (NewSize > MaxNewSize) {

     if (FLAG_IS_CMDLINE(MaxNewSize)) {

       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "

               "A new max generation size of " SIZE_FORMAT "k will be used.",

               NewSize/K, MaxNewSize/K, NewSize/K);

     }

     MaxNewSize = NewSize;

   }

   if (FLAG_IS_CMDLINE(NewSize)) {

     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),

                                      1U);

     if (FLAG_IS_CMDLINE(MaxNewSize)) {

       _max_desired_young_length =

                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),

                                   1U);

       _sizer_kind = SizerMaxAndNewSize;

       _adaptive_size = _min_desired_young_length == _max_desired_young_length;

     } else {

       _sizer_kind = SizerNewSizeOnly;

     }

   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {

     _max_desired_young_length =

                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),

                                   1U);

     _sizer_kind = SizerMaxNewSizeOnly;

   }

 }

 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {

   uint default_value = (new_number_of_heap_regions * G1NewSizePercent) / 100;

   return MAX2(1U, default_value);

 }

 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {

   uint default_value = (new_number_of_heap_regions * G1MaxNewSizePercent) / 100;

   return MAX2(1U, default_value);

 }

 void G1YoungGenSizer::recalculate_min_max_young_length(uint number_of_heap_regions, uint* min_young_length, uint* max_young_length) {

   assert(number_of_heap_regions > 0, "Heap must be initialized");

   switch (_sizer_kind) {

     case SizerDefaults:

       *min_young_length = calculate_default_min_length(number_of_heap_regions);

       *max_young_length = calculate_default_max_length(number_of_heap_regions);

       break;

     case SizerNewSizeOnly:

       *max_young_length = calculate_default_max_length(number_of_heap_regions);

       *max_young_length = MAX2(*min_young_length, *max_young_length);

       break;

     case SizerMaxNewSizeOnly:

       *min_young_length = calculate_default_min_length(number_of_heap_regions);

       *min_young_length = MIN2(*min_young_length, *max_young_length);

       break;

     case SizerMaxAndNewSize:

       // Do nothing. Values set on the command line, don't update them at runtime.

       break;

     case SizerNewRatio:

       *min_young_length = number_of_heap_regions / (NewRatio + 1);

       *max_young_length = *min_young_length;

       break;

     default:

       ShouldNotReachHere();

   }

   assert(*min_young_length <= *max_young_length, "Invalid min/max young gen size values");

 }

 uint G1YoungGenSizer::max_young_length(uint number_of_heap_regions) {

   // We need to pass the desired values because recalculation may not update these

   // values in some cases.

   uint temp = _min_desired_young_length;

   uint result = _max_desired_young_length;

   recalculate_min_max_young_length(number_of_heap_regions, &temp, &result);

   return result;

 }

 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {

   recalculate_min_max_young_length(new_number_of_heap_regions, &_min_desired_young_length,

           &_max_desired_young_length);

 }

 void G1CollectorPolicy::init() {

   // Set aside an initial future to_space.

   _g1 = G1CollectedHeap::heap();

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

   initialize_gc_policy_counters();

   if (adaptive_young_list_length()) {

     _young_list_fixed_length = 0;

   } else {

     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();

   }

   _free_regions_at_end_of_collection = _g1->num_free_regions();

   update_young_list_target_length();

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

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

   start_incremental_cset_building();

 }

 // Create the jstat counters for the policy.

 void G1CollectorPolicy::initialize_gc_policy_counters() {

   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);

 }

 bool G1CollectorPolicy::predict_will_fit(uint young_length,

                                          double base_time_ms,

                                          uint base_free_regions,

                                          double target_pause_time_ms) {

   if (young_length >= base_free_regions) {

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

     return false;

   }

   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);

   size_t bytes_to_copy =

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

   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);

   double young_other_time_ms = predict_young_other_time_ms(young_length);

   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;

   if (pause_time_ms > target_pause_time_ms) {

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

     return false;

   }

   size_t free_bytes =

                    (base_free_regions - young_length) * HeapRegion::GrainBytes;

   if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {

     // end condition 3: out-of-space (conservatively!)

     return false;

   }

   // success!

   return true;

 }

 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {

   // re-calculate the necessary reserve

   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;

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

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

   _reserve_regions = (uint) ceil(reserve_regions_d);

   _young_gen_sizer->heap_size_changed(new_number_of_regions);

 }

 uint G1CollectorPolicy::calculate_young_list_desired_min_length(

                                                        uint base_min_length) {

   uint desired_min_length = 0;

   if (adaptive_young_list_length()) {

     if (_alloc_rate_ms_seq->num() > 3) {

       double now_sec = os::elapsedTime();

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

       double alloc_rate_ms = predict_alloc_rate_ms();

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

     } else {

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

     }

   }

   desired_min_length += base_min_length;

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

   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);

 }

 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {

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

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

   // effectively don't set this bound.

   return _young_gen_sizer->max_desired_young_length();

 }

 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {

   if (rs_lengths == (size_t) -1) {

     // if it's set to the default value (-1), we should predict it;

     // otherwise, use the given value.

     rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);

   }

   // Calculate the absolute and desired min bounds.

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

   uint base_min_length = recorded_survivor_regions();

   // This is the absolute minimum young length, which ensures that we

   // can allocate one eden region in the worst-case.

   uint absolute_min_length = base_min_length + 1;

   uint desired_min_length =

                      calculate_young_list_desired_min_length(base_min_length);

   if (desired_min_length < absolute_min_length) {

     desired_min_length = absolute_min_length;

   }

   // Calculate the absolute and desired max bounds.

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

   uint absolute_max_length = 0;

   if (_free_regions_at_end_of_collection > _reserve_regions) {

     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;

   }

   uint desired_max_length = calculate_young_list_desired_max_length();

   if (desired_max_length > absolute_max_length) {

     desired_max_length = absolute_max_length;

   }

   uint young_list_target_length = 0;

   if (adaptive_young_list_length()) {

     if (gcs_are_young()) {

       young_list_target_length =

                         calculate_young_list_target_length(rs_lengths,

                                                            base_min_length,

                                                            desired_min_length,

                                                            desired_max_length);

       _rs_lengths_prediction = rs_lengths;

     } else {

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

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

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

     }

   } else {

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

     // whether the next GC is young or mixed.

     young_list_target_length = _young_list_fixed_length;

   }

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

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

   // which is why that test is second.

   if (young_list_target_length > desired_max_length) {

     young_list_target_length = desired_max_length;

   }

   if (young_list_target_length < desired_min_length) {

     young_list_target_length = desired_min_length;

   }

   assert(young_list_target_length > recorded_survivor_regions(),

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

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

   _young_list_target_length = young_list_target_length;

   update_max_gc_locker_expansion();

 }

 uint

 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,

                                                      uint base_min_length,

                                                      uint desired_min_length,

                                                      uint desired_max_length) {

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

   assert(gcs_are_young(), "only call this for young GCs");

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

   if (desired_max_length <= desired_min_length) {

     return desired_min_length;

   }

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

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

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

   // will be reflected in the predictions by the

   // survivor_regions_evac_time prediction.

   assert(desired_min_length > base_min_length, "invariant");

   uint min_young_length = desired_min_length - base_min_length;

   assert(desired_max_length > base_min_length, "invariant");

   uint max_young_length = desired_max_length - base_min_length;

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

   double survivor_regions_evac_time = predict_survivor_regions_evac_time();

   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);

   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();

   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);

   double base_time_ms =

     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +

     survivor_regions_evac_time;

   uint available_free_regions = _free_regions_at_end_of_collection;

   uint base_free_regions = 0;

   if (available_free_regions > _reserve_regions) {

     base_free_regions = available_free_regions - _reserve_regions;

   }

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

   // makes sense fits within the target pause time.

   if (predict_will_fit(min_young_length, base_time_ms,

                        base_free_regions, target_pause_time_ms)) {

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

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

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

     // a binary search between min_young_length and max_young_length.

     if (predict_will_fit(max_young_length, base_time_ms,

                          base_free_regions, target_pause_time_ms)) {

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

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

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

       min_young_length = max_young_length;

     } else {

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

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

       // length. The loop invariants are:

       //

       // min_young_length < max_young_length

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

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

       //

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

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

       // the middle value between min_young_length and

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

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

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

       assert(min_young_length < max_young_length, "invariant");

       uint diff = (max_young_length - min_young_length) / 2;

       while (diff > 0) {

         uint young_length = min_young_length + diff;

         if (predict_will_fit(young_length, base_time_ms,

                              base_free_regions, target_pause_time_ms)) {

           min_young_length = young_length;

         } else {

           max_young_length = young_length;

         }

         assert(min_young_length <  max_young_length, "invariant");

         diff = (max_young_length - min_young_length) / 2;

       }

       // The results is min_young_length which, according to the

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

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

       assert(min_young_length < max_young_length,

              "otherwise we should have discovered that max_young_length "

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

       assert(predict_will_fit(min_young_length, base_time_ms,

                               base_free_regions, target_pause_time_ms),

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

              "fit into the pause target");

       assert(!predict_will_fit(min_young_length + 1, base_time_ms,

                                base_free_regions, target_pause_time_ms),

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

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

     }

   } else {

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

     // target, return it as the result nevertheless.

   }

   return base_min_length + min_young_length;

 }

 double G1CollectorPolicy::predict_survivor_regions_evac_time() {

   double survivor_regions_evac_time = 0.0;

   for (HeapRegion * r = _recorded_survivor_head;

        r != NULL && r != _recorded_survivor_tail->get_next_young_region();

        r = r->get_next_young_region()) {

     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, gcs_are_young());

   }

   return survivor_regions_evac_time;

 }

 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {

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

   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();

   if (rs_lengths > _rs_lengths_prediction) {

     // add 10% to avoid having to recalculate often

     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;

     update_young_list_target_length(rs_lengths_prediction);

   }

 }

 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,

                                                bool is_tlab,

                                                bool* gc_overhead_limit_was_exceeded) {

   guarantee(false, "Not using this policy feature yet.");

   return NULL;

 }

 // This method controls how a collector handles one or more

 // of its generations being fully allocated.

 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,

                                                        bool is_tlab) {

   guarantee(false, "Not using this policy feature yet.");

   return NULL;

 }

 #ifndef PRODUCT

 bool G1CollectorPolicy::verify_young_ages() {

   HeapRegion* head = _g1->young_list()->first_region();

   return

     verify_young_ages(head, _short_lived_surv_rate_group);

   // also call verify_young_ages on any additional surv rate groups

 }

 bool

 G1CollectorPolicy::verify_young_ages(HeapRegion* head,

                                      SurvRateGroup *surv_rate_group) {

   guarantee( surv_rate_group != NULL, "pre-condition" );

   const char* name = surv_rate_group->name();

   bool ret = true;

   int prev_age = -1;

   for (HeapRegion* curr = head;

        curr != NULL;

        curr = curr->get_next_young_region()) {

     SurvRateGroup* group = curr->surv_rate_group();

     if (group == NULL && !curr->is_survivor()) {

       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);

       ret = false;

     }

     if (surv_rate_group == group) {

       int age = curr->age_in_surv_rate_group();

       if (age < 0) {

         gclog_or_tty->print_cr("## %s: encountered negative age", name);

         ret = false;

       }

       if (age <= prev_age) {

         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "

                                "(%d, %d)", name, age, prev_age);

         ret = false;

       }

       prev_age = age;

     }

   }

   return ret;

 }

 #endif // PRODUCT

 void G1CollectorPolicy::record_full_collection_start() {

   _full_collection_start_sec = os::elapsedTime();

   record_heap_size_info_at_start(true /* full */);

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

   _g1->set_full_collection();

 }

 void G1CollectorPolicy::record_full_collection_end() {

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

   // since last pause.

   double end_sec = os::elapsedTime();

   double full_gc_time_sec = end_sec - _full_collection_start_sec;

   double full_gc_time_ms = full_gc_time_sec * 1000.0;

   _trace_gen1_time_data.record_full_collection(full_gc_time_ms);

   update_recent_gc_times(end_sec, full_gc_time_ms);

   _g1->clear_full_collection();

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

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

   set_gcs_are_young(true);

   _last_young_gc = false;

   clear_initiate_conc_mark_if_possible();

   clear_during_initial_mark_pause();

   _in_marking_window = false;

   _in_marking_window_im = false;

   _short_lived_surv_rate_group->start_adding_regions();

   // also call this on any additional surv rate groups

   record_survivor_regions(0, NULL, NULL);

   _free_regions_at_end_of_collection = _g1->num_free_regions();

   // Reset survivors SurvRateGroup.

   _survivor_surv_rate_group->reset();

   update_young_list_target_length();

   _collectionSetChooser->clear();

 }

 void G1CollectorPolicy::record_stop_world_start() {

   _stop_world_start = os::elapsedTime();

 }

 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {

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

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

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

   update_survivors_policy();

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

          err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,

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

   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;

   _trace_gen0_time_data.record_start_collection(s_w_t_ms);

   _stop_world_start = 0.0;

   record_heap_size_info_at_start(false /* full */);

   phase_times()->record_cur_collection_start_sec(start_time_sec);

   _pending_cards = _g1->pending_card_num();

   _collection_set_bytes_used_before = 0;

   _bytes_copied_during_gc = 0;

   _last_gc_was_young = false;

   // do that for any other surv rate groups

   _short_lived_surv_rate_group->stop_adding_regions();

   _survivors_age_table.clear();

   assert( verify_young_ages(), "region age verification" );

 }

 void G1CollectorPolicy::record_concurrent_mark_init_end(double

                                                    mark_init_elapsed_time_ms) {

   _during_marking = true;

   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");

   clear_during_initial_mark_pause();

   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;

 }

 void G1CollectorPolicy::record_concurrent_mark_remark_start() {

   _mark_remark_start_sec = os::elapsedTime();

   _during_marking = false;

 }

 void G1CollectorPolicy::record_concurrent_mark_remark_end() {

   double end_time_sec = os::elapsedTime();

   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;

   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);

   _cur_mark_stop_world_time_ms += elapsed_time_ms;

   _prev_collection_pause_end_ms += elapsed_time_ms;

   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);

 }

 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {

   _mark_cleanup_start_sec = os::elapsedTime();

 }

 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {

   _last_young_gc = true;

   _in_marking_window = false;

 }

 void G1CollectorPolicy::record_concurrent_pause() {

   if (_stop_world_start > 0.0) {

     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;

     _trace_gen0_time_data.record_yield_time(yield_ms);

   }

 }

 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {

   if (_g1->concurrent_mark()->cmThread()->during_cycle()) {

     return false;

   }

   size_t marking_initiating_used_threshold =

     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;

   size_t cur_used_bytes = _g1->non_young_capacity_bytes();

   size_t alloc_byte_size = alloc_word_size * HeapWordSize;

   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {

     if (gcs_are_young() && !_last_young_gc) {

       ergo_verbose5(ErgoConcCycles,

         "request concurrent cycle initiation",

         ergo_format_reason("occupancy higher than threshold")

         ergo_format_byte("occupancy")

         ergo_format_byte("allocation request")

         ergo_format_byte_perc("threshold")

         ergo_format_str("source"),

         cur_used_bytes,

         alloc_byte_size,

         marking_initiating_used_threshold,

         (double) InitiatingHeapOccupancyPercent,

         source);

       return true;

     } else {

       ergo_verbose5(ErgoConcCycles,

         "do not request concurrent cycle initiation",

         ergo_format_reason("still doing mixed collections")

         ergo_format_byte("occupancy")

         ergo_format_byte("allocation request")

         ergo_format_byte_perc("threshold")

         ergo_format_str("source"),

         cur_used_bytes,

         alloc_byte_size,

         marking_initiating_used_threshold,

         (double) InitiatingHeapOccupancyPercent,

         source);

     }

   }

   return false;

 }

 // Anything below that is considered to be zero

 #define MIN_TIMER_GRANULARITY 0.0000001

 void G1CollectorPolicy::record_collection_pause_end(double pause_time_ms, EvacuationInfo& evacuation_info) {

   double end_time_sec = os::elapsedTime();

   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),

          "otherwise, the subtraction below does not make sense");

   size_t rs_size =

             _cur_collection_pause_used_regions_at_start - cset_region_length();

   size_t cur_used_bytes = _g1->used();

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

   bool last_pause_included_initial_mark = false;

   bool update_stats = !_g1->evacuation_failed();

 #ifndef PRODUCT

   if (G1YoungSurvRateVerbose) {

     gclog_or_tty->cr();

     _short_lived_surv_rate_group->print();

     // do that for any other surv rate groups too

   }

 #endif // PRODUCT

   last_pause_included_initial_mark = during_initial_mark_pause();

   if (last_pause_included_initial_mark) {

     record_concurrent_mark_init_end(0.0);

   } else if (need_to_start_conc_mark("end of GC")) {

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

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

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

     set_initiate_conc_mark_if_possible();

   }

   _mmu_tracker->add_pause(end_time_sec - pause_time_ms/1000.0,

                           end_time_sec, false);

   evacuation_info.set_collectionset_used_before(_collection_set_bytes_used_before);

   evacuation_info.set_bytes_copied(_bytes_copied_during_gc);

   if (update_stats) {

     _trace_gen0_time_data.record_end_collection(pause_time_ms, phase_times());

     // this is where we update the allocation rate of the application

     double app_time_ms =

       (phase_times()->cur_collection_start_sec() * 1000.0 - _prev_collection_pause_end_ms);

     if (app_time_ms < MIN_TIMER_GRANULARITY) {

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

       // granularity. Some Linuxes are the usual culprits.

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

       app_time_ms = 1.0;

     }

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

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

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

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

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

     // given that humongous object allocations do not really affect

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

     // place we can safely ignore them here.

     uint regions_allocated = eden_cset_region_length();

     double alloc_rate_ms = (double) regions_allocated / app_time_ms;

     _alloc_rate_ms_seq->add(alloc_rate_ms);

     double interval_ms =

       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;

     update_recent_gc_times(end_time_sec, pause_time_ms);

     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;

     if (recent_avg_pause_time_ratio() < 0.0 ||

         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {

 #ifndef PRODUCT

       // Dump info to allow post-facto debugging

       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");

       gclog_or_tty->print_cr("-------------------------------------------");

       gclog_or_tty->print_cr("Recent GC Times (ms):");

       _recent_gc_times_ms->dump();

       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);

       _recent_prev_end_times_for_all_gcs_sec->dump();

       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",

                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());

       // In debug mode, terminate the JVM if the user wants to debug at this point.

       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");

 #endif  // !PRODUCT

       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in

       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.

       if (_recent_avg_pause_time_ratio < 0.0) {

         _recent_avg_pause_time_ratio = 0.0;

       } else {

         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");

         _recent_avg_pause_time_ratio = 1.0;

       }

     }

   }

   bool new_in_marking_window = _in_marking_window;

   bool new_in_marking_window_im = false;

   if (last_pause_included_initial_mark) {

     new_in_marking_window = true;

     new_in_marking_window_im = true;

   }

   if (_last_young_gc) {

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

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

     if (!last_pause_included_initial_mark) {

       if (next_gc_should_be_mixed("start mixed GCs",

                                   "do not start mixed GCs")) {

         set_gcs_are_young(false);

       }

     } else {

       ergo_verbose0(ErgoMixedGCs,

                     "do not start mixed GCs",

                     ergo_format_reason("concurrent cycle is about to start"));

     }

     _last_young_gc = false;

   }

   if (!_last_gc_was_young) {

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

     // mixed GCs or not.

     if (!next_gc_should_be_mixed("continue mixed GCs",

                                  "do not continue mixed GCs")) {

       set_gcs_are_young(true);

     }

   }

   _short_lived_surv_rate_group->start_adding_regions();

   // do that for any other surv rate groupsx

   if (update_stats) {

     double cost_per_card_ms = 0.0;

     if (_pending_cards > 0) {

       cost_per_card_ms = phase_times()->average_last_update_rs_time() / (double) _pending_cards;

       _cost_per_card_ms_seq->add(cost_per_card_ms);

     }

     size_t cards_scanned = _g1->cards_scanned();

     double cost_per_entry_ms = 0.0;

     if (cards_scanned > 10) {

       cost_per_entry_ms = phase_times()->average_last_scan_rs_time() / (double) cards_scanned;

       if (_last_gc_was_young) {

         _cost_per_entry_ms_seq->add(cost_per_entry_ms);

       } else {

         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);

       }

     }

     if (_max_rs_lengths > 0) {

       double cards_per_entry_ratio =

         (double) cards_scanned / (double) _max_rs_lengths;

       if (_last_gc_was_young) {

         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);

       } else {

         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);

       }

     }

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

     // smaller than _recorded_rs_lengths which was causing

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

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

     // _inc_cset_recorded_rs_lengths field which the code below guards

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

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

     // _inc_cset_recorded_rs_lengths might still end up somewhat

     // inaccurate. The concurrent refinement thread calculates an

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

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

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

     // conditional below just in case.

     size_t rs_length_diff = 0;

     if (_max_rs_lengths > _recorded_rs_lengths) {

       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;

     }

     _rs_length_diff_seq->add((double) rs_length_diff);

     size_t freed_bytes = _heap_used_bytes_before_gc - cur_used_bytes;

     size_t copied_bytes = _collection_set_bytes_used_before - freed_bytes;

     double cost_per_byte_ms = 0.0;

     if (copied_bytes > 0) {

       cost_per_byte_ms = phase_times()->average_last_obj_copy_time() / (double) copied_bytes;

       if (_in_marking_window) {

         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);

       } else {

         _cost_per_byte_ms_seq->add(cost_per_byte_ms);

       }

     }

     double all_other_time_ms = pause_time_ms -

       (phase_times()->average_last_update_rs_time() + phase_times()->average_last_scan_rs_time()

       + phase_times()->average_last_obj_copy_time() + phase_times()->average_last_termination_time());

     double young_other_time_ms = 0.0;

     if (young_cset_region_length() > 0) {

       young_other_time_ms =

         phase_times()->young_cset_choice_time_ms() +

         phase_times()->young_free_cset_time_ms();

       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /

                                           (double) young_cset_region_length());

     }

     double non_young_other_time_ms = 0.0;

     if (old_cset_region_length() > 0) {

       non_young_other_time_ms =

         phase_times()->non_young_cset_choice_time_ms() +

         phase_times()->non_young_free_cset_time_ms();

       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /

                                             (double) old_cset_region_length());

     }

     double constant_other_time_ms = all_other_time_ms -

       (young_other_time_ms + non_young_other_time_ms);

     _constant_other_time_ms_seq->add(constant_other_time_ms);

     double survival_ratio = 0.0;

     if (_collection_set_bytes_used_before > 0) {

       survival_ratio = (double) _bytes_copied_during_gc /

                                    (double) _collection_set_bytes_used_before;

     }

     _pending_cards_seq->add((double) _pending_cards);

     _rs_lengths_seq->add((double) _max_rs_lengths);

   }

   _in_marking_window = new_in_marking_window;

   _in_marking_window_im = new_in_marking_window_im;

   _free_regions_at_end_of_collection = _g1->num_free_regions();

   update_young_list_target_length();

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

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

   adjust_concurrent_refinement(phase_times()->average_last_update_rs_time(),

                                phase_times()->sum_last_update_rs_processed_buffers(), update_rs_time_goal_ms);

   _collectionSetChooser->verify();

 }

 #define EXT_SIZE_FORMAT "%.1f%s"

 #define EXT_SIZE_PARAMS(bytes)                                  \

   byte_size_in_proper_unit((double)(bytes)),                    \

   proper_unit_for_byte_size((bytes))

 void G1CollectorPolicy::record_heap_size_info_at_start(bool full) {

   YoungList* young_list = _g1->young_list();

   _eden_used_bytes_before_gc = young_list->eden_used_bytes();

   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();

   _heap_capacity_bytes_before_gc = _g1->capacity();

   _heap_used_bytes_before_gc = _g1->used();

   _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();

   _eden_capacity_bytes_before_gc =

          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;

   if (full) {

     _metaspace_used_bytes_before_gc = MetaspaceAux::used_bytes();

   }

 }

 void G1CollectorPolicy::print_heap_transition() {

   _g1->print_size_transition(gclog_or_tty,

                              _heap_used_bytes_before_gc,

                              _g1->used(),

                              _g1->capacity());

 }

 void G1CollectorPolicy::print_detailed_heap_transition(bool full) {

   YoungList* young_list = _g1->young_list();

   size_t eden_used_bytes_after_gc = young_list->eden_used_bytes();

   size_t survivor_used_bytes_after_gc = young_list->survivor_used_bytes();

   size_t heap_used_bytes_after_gc = _g1->used();

   size_t heap_capacity_bytes_after_gc = _g1->capacity();

   size_t eden_capacity_bytes_after_gc =

     (_young_list_target_length * HeapRegion::GrainBytes) - survivor_used_bytes_after_gc;

   gclog_or_tty->print(

     "   [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "

     "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "

     "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"

     EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",

     EXT_SIZE_PARAMS(_eden_used_bytes_before_gc),

     EXT_SIZE_PARAMS(_eden_capacity_bytes_before_gc),

     EXT_SIZE_PARAMS(eden_used_bytes_after_gc),

     EXT_SIZE_PARAMS(eden_capacity_bytes_after_gc),

     EXT_SIZE_PARAMS(_survivor_used_bytes_before_gc),

     EXT_SIZE_PARAMS(survivor_used_bytes_after_gc),

     EXT_SIZE_PARAMS(_heap_used_bytes_before_gc),

     EXT_SIZE_PARAMS(_heap_capacity_bytes_before_gc),

     EXT_SIZE_PARAMS(heap_used_bytes_after_gc),

     EXT_SIZE_PARAMS(heap_capacity_bytes_after_gc));

   if (full) {

     MetaspaceAux::print_metaspace_change(_metaspace_used_bytes_before_gc);

   }

   gclog_or_tty->cr();

 }

 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,

                                                      double update_rs_processed_buffers,

                                                      double goal_ms) {

   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();

   if (G1UseAdaptiveConcRefinement) {

     const int k_gy = 3, k_gr = 6;

     const double inc_k = 1.1, dec_k = 0.9;

     int g = cg1r->green_zone();

     if (update_rs_time > goal_ms) {

       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.

     } else {

       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {

         g = (int)MAX2(g * inc_k, g + 1.0);

       }

     }

     // Change the refinement threads params

     cg1r->set_green_zone(g);

     cg1r->set_yellow_zone(g * k_gy);

     cg1r->set_red_zone(g * k_gr);

     cg1r->reinitialize_threads();

     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);

     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,

                                     cg1r->yellow_zone());

     // Change the barrier params

     dcqs.set_process_completed_threshold(processing_threshold);

     dcqs.set_max_completed_queue(cg1r->red_zone());

   }

   int curr_queue_size = dcqs.completed_buffers_num();

   if (curr_queue_size >= cg1r->yellow_zone()) {

     dcqs.set_completed_queue_padding(curr_queue_size);

   } else {

     dcqs.set_completed_queue_padding(0);

   }

   dcqs.notify_if_necessary();

 }

 double

 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,

                                                 size_t scanned_cards) {

   return

     predict_rs_update_time_ms(pending_cards) +

     predict_rs_scan_time_ms(scanned_cards) +

     predict_constant_other_time_ms();

 }

 double

 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {

   size_t rs_length = predict_rs_length_diff();

   size_t card_num;

   if (gcs_are_young()) {

     card_num = predict_young_card_num(rs_length);

   } else {

     card_num = predict_non_young_card_num(rs_length);

   }

   return predict_base_elapsed_time_ms(pending_cards, card_num);

 }

 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {

   size_t bytes_to_copy;

   if (hr->is_marked())

     bytes_to_copy = hr->max_live_bytes();

   else {

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

     int age = hr->age_in_surv_rate_group();

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

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

   }

   return bytes_to_copy;

 }

 double

 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,

                                                   bool for_young_gc) {

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

   size_t card_num;

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

   // we're predicting for.

   if (for_young_gc) {

     card_num = predict_young_card_num(rs_length);

   } else {

     card_num = predict_non_young_card_num(rs_length);

   }

   size_t bytes_to_copy = predict_bytes_to_copy(hr);

   double region_elapsed_time_ms =

     predict_rs_scan_time_ms(card_num) +

     predict_object_copy_time_ms(bytes_to_copy);

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

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

   if (hr->is_young()) {

     region_elapsed_time_ms += predict_young_other_time_ms(1);

   } else {

     region_elapsed_time_ms += predict_non_young_other_time_ms(1);

   }

   return region_elapsed_time_ms;

 }

 void

 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,

                                             uint survivor_cset_region_length) {

   _eden_cset_region_length     = eden_cset_region_length;

   _survivor_cset_region_length = survivor_cset_region_length;

   _old_cset_region_length      = 0;

 }

 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {

   _recorded_rs_lengths = rs_lengths;

 }

 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,

                                                double elapsed_ms) {

   _recent_gc_times_ms->add(elapsed_ms);

   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);

   _prev_collection_pause_end_ms = end_time_sec * 1000.0;

 }

 size_t G1CollectorPolicy::expansion_amount() {

   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;

   double threshold = _gc_overhead_perc;

   if (recent_gc_overhead > threshold) {

     // We will double the existing space, or take

     // G1ExpandByPercentOfAvailable % of the available expansion

     // space, whichever is smaller, bounded below by a minimum

     // expansion (unless that's all that's left.)

     const size_t min_expand_bytes = 1*M;

     size_t reserved_bytes = _g1->max_capacity();

     size_t committed_bytes = _g1->capacity();

     size_t uncommitted_bytes = reserved_bytes - committed_bytes;

     size_t expand_bytes;

     size_t expand_bytes_via_pct =

       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;

     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);

     expand_bytes = MAX2(expand_bytes, min_expand_bytes);

     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);

     ergo_verbose5(ErgoHeapSizing,

                   "attempt heap expansion",

                   ergo_format_reason("recent GC overhead higher than "

                                      "threshold after GC")

                   ergo_format_perc("recent GC overhead")

                   ergo_format_perc("threshold")

                   ergo_format_byte("uncommitted")

                   ergo_format_byte_perc("calculated expansion amount"),

                   recent_gc_overhead, threshold,

                   uncommitted_bytes,

                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);

     return expand_bytes;

   } else {

     return 0;

   }

 }

 void G1CollectorPolicy::print_tracing_info() const {

   _trace_gen0_time_data.print();

   _trace_gen1_time_data.print();

 }

 void G1CollectorPolicy::print_yg_surv_rate_info() const {

 #ifndef PRODUCT

   _short_lived_surv_rate_group->print_surv_rate_summary();

   // add this call for any other surv rate groups

 #endif // PRODUCT

 }

 bool G1CollectorPolicy::is_young_list_full() {

   uint young_list_length = _g1->young_list()->length();

   uint young_list_target_length = _young_list_target_length;

   return young_list_length >= young_list_target_length;

 }

 bool G1CollectorPolicy::can_expand_young_list() {

   uint young_list_length = _g1->young_list()->length();

   uint young_list_max_length = _young_list_max_length;

   return young_list_length < young_list_max_length;

 }

 uint G1CollectorPolicy::max_regions(int purpose) {

   switch (purpose) {

     case GCAllocForSurvived:

       return _max_survivor_regions;

     case GCAllocForTenured:

       return REGIONS_UNLIMITED;

     default:

       ShouldNotReachHere();

       return REGIONS_UNLIMITED;

   };

 }

 void G1CollectorPolicy::update_max_gc_locker_expansion() {

   uint expansion_region_num = 0;

   if (GCLockerEdenExpansionPercent > 0) {

     double perc = (double) GCLockerEdenExpansionPercent / 100.0;

     double expansion_region_num_d = perc * (double) _young_list_target_length;

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

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

     expansion_region_num = (uint) ceil(expansion_region_num_d);

   } else {

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

   }

   _young_list_max_length = _young_list_target_length + expansion_region_num;

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

 }

 // Calculates survivor space parameters.

 void G1CollectorPolicy::update_survivors_policy() {

   double max_survivor_regions_d =

                  (double) _young_list_target_length / (double) SurvivorRatio;

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

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

   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);

   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(

         HeapRegion::GrainWords * _max_survivor_regions);

 }

 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(

                                                      GCCause::Cause gc_cause) {

   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();

   if (!during_cycle) {

     ergo_verbose1(ErgoConcCycles,

                   "request concurrent cycle initiation",

                   ergo_format_reason("requested by GC cause")

                   ergo_format_str("GC cause"),

                   GCCause::to_string(gc_cause));

     set_initiate_conc_mark_if_possible();

     return true;

   } else {

     ergo_verbose1(ErgoConcCycles,

                   "do not request concurrent cycle initiation",

                   ergo_format_reason("concurrent cycle already in progress")

                   ergo_format_str("GC cause"),

                   GCCause::to_string(gc_cause));

     return false;

   }

 }

 void

 G1CollectorPolicy::decide_on_conc_mark_initiation() {

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

   // initial-mark pause.

   // First, during_initial_mark_pause() should not be already set. We

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

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

   // initial-mark pause).

   assert(!during_initial_mark_pause(), "pre-condition");

   if (initiate_conc_mark_if_possible()) {

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

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

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

     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();

     if (!during_cycle) {

       // The concurrent marking thread is not "during a cycle", i.e.,

       // it has completed the last one. So we can go ahead and

       // initiate a new cycle.

       set_during_initial_mark_pause();

       // We do not allow mixed GCs during marking.

       if (!gcs_are_young()) {

         set_gcs_are_young(true);

         ergo_verbose0(ErgoMixedGCs,

                       "end mixed GCs",

                       ergo_format_reason("concurrent cycle is about to start"));

       }

       // And we can now clear initiate_conc_mark_if_possible() as

       // we've already acted on it.

       clear_initiate_conc_mark_if_possible();

       ergo_verbose0(ErgoConcCycles,

                   "initiate concurrent cycle",

                   ergo_format_reason("concurrent cycle initiation requested"));

     } else {

       // The concurrent marking thread is still finishing up the

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

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

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

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

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

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

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

       // periodically yields while clearing the next marking bitmap

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

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

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

       ergo_verbose0(ErgoConcCycles,

                     "do not initiate concurrent cycle",

                     ergo_format_reason("concurrent cycle already in progress"));

     }

   }

 }

 class KnownGarbageClosure: public HeapRegionClosure {

   G1CollectedHeap* _g1h;

   CollectionSetChooser* _hrSorted;

 public:

   KnownGarbageClosure(CollectionSetChooser* hrSorted) :

     _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }

   bool doHeapRegion(HeapRegion* r) {

     // We only include humongous regions in collection

     // sets when concurrent mark shows that their contained object is

     // unreachable.

     // Do we have any marking information for this region?

     if (r->is_marked()) {

       // We will skip any region that's currently used as an old GC

       // alloc region (we should not consider those for collection

       // before we fill them up).

       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {

         _hrSorted->add_region(r);

       }

     }

     return false;

   }

 };

 class ParKnownGarbageHRClosure: public HeapRegionClosure {

   G1CollectedHeap* _g1h;

   CSetChooserParUpdater _cset_updater;

 public:

   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,

                            uint chunk_size) :

     _g1h(G1CollectedHeap::heap()),

     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }

   bool doHeapRegion(HeapRegion* r) {

     // Do we have any marking information for this region?

     if (r->is_marked()) {

       // We will skip any region that's currently used as an old GC

       // alloc region (we should not consider those for collection

       // before we fill them up).

       if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {

         _cset_updater.add_region(r);

       }

     }

     return false;

   }

 };

 class ParKnownGarbageTask: public AbstractGangTask {

   CollectionSetChooser* _hrSorted;

   uint _chunk_size;

   G1CollectedHeap* _g1;

 public:

   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :

     AbstractGangTask("ParKnownGarbageTask"),

     _hrSorted(hrSorted), _chunk_size(chunk_size),

     _g1(G1CollectedHeap::heap()) { }

   void work(uint worker_id) {

     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);

     // Back to zero for the claim value.

     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,

                                          _g1->workers()->active_workers(),

                                          HeapRegion::InitialClaimValue);

   }

 };

 void

 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {

   _collectionSetChooser->clear();

   uint region_num = _g1->num_regions();

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     const uint OverpartitionFactor = 4;

     uint WorkUnit;

     // The use of MinChunkSize = 8 in the original code

     // causes some assertion failures when the total number of

     // region is less than 8.  The code here tries to fix that.

     // Should the original code also be fixed?

     if (no_of_gc_threads > 0) {

       const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);

       WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),

                       MinWorkUnit);

     } else {

       assert(no_of_gc_threads > 0,

         "The active gc workers should be greater than 0");

       // In a product build do something reasonable to avoid a crash.

       const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);

       WorkUnit =

         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),

              MinWorkUnit);

     }

     _collectionSetChooser->prepare_for_par_region_addition(_g1->num_regions(),

                                                            WorkUnit);

     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,

                                             (int) WorkUnit);

     _g1->workers()->run_task(&parKnownGarbageTask);

     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),

            "sanity check");

   } else {

     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);

     _g1->heap_region_iterate(&knownGarbagecl);

   }

   _collectionSetChooser->sort_regions();

   double end_sec = os::elapsedTime();

   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;

   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);

   _cur_mark_stop_world_time_ms += elapsed_time_ms;

   _prev_collection_pause_end_ms += elapsed_time_ms;

   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);

 }

 // Add the heap region at the head of the non-incremental collection set

 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {

   assert(_inc_cset_build_state == Active, "Precondition");

   assert(hr->is_old(), "the region should be old");

   assert(!hr->in_collection_set(), "should not already be in the CSet");

   hr->set_in_collection_set(true);

   hr->set_next_in_collection_set(_collection_set);

   _collection_set = hr;

   _collection_set_bytes_used_before += hr->used();

   _g1->register_region_with_in_cset_fast_test(hr);

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

   _recorded_rs_lengths += rs_length;

   _old_cset_region_length += 1;

 }

 // Initialize the per-collection-set information

 void G1CollectorPolicy::start_incremental_cset_building() {

   assert(_inc_cset_build_state == Inactive, "Precondition");

   _inc_cset_head = NULL;

   _inc_cset_tail = NULL;

   _inc_cset_bytes_used_before = 0;

   _inc_cset_max_finger = 0;

   _inc_cset_recorded_rs_lengths = 0;

   _inc_cset_recorded_rs_lengths_diffs = 0;

   _inc_cset_predicted_elapsed_time_ms = 0.0;

   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;

   _inc_cset_build_state = Active;

 }

 void G1CollectorPolicy::finalize_incremental_cset_building() {

   assert(_inc_cset_build_state == Active, "Precondition");

   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");

   // The two "main" fields, _inc_cset_recorded_rs_lengths and

   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread

   // that adds a new region to the CSet. Further updates by the

   // concurrent refinement thread that samples the young RSet lengths

   // are accumulated in the *_diffs fields. Here we add the diffs to

   // the "main" fields.

   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {

     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;

   } else {

     // This is defensive. The diff should in theory be always positive

     // as RSets can only grow between GCs. However, given that we

     // sample their size concurrently with other threads updating them

     // it's possible that we might get the wrong size back, which

     // could make the calculations somewhat inaccurate.

     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);

     if (_inc_cset_recorded_rs_lengths >= diffs) {

       _inc_cset_recorded_rs_lengths -= diffs;

     } else {

       _inc_cset_recorded_rs_lengths = 0;

     }

   }

   _inc_cset_predicted_elapsed_time_ms +=

                                      _inc_cset_predicted_elapsed_time_ms_diffs;

   _inc_cset_recorded_rs_lengths_diffs = 0;

   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;

 }

 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {

   // This routine is used when:

   // * adding survivor regions to the incremental cset at the end of an

   //   evacuation pause,

   // * adding the current allocation region to the incremental cset

   //   when it is retired, and

   // * updating existing policy information for a region in the

   //   incremental cset via young list RSet sampling.

   // Therefore this routine may be called at a safepoint by the

   // VM thread, or in-between safepoints by mutator threads (when

   // retiring the current allocation region) or a concurrent

   // refine thread (RSet sampling).

   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());

   size_t used_bytes = hr->used();

   _inc_cset_recorded_rs_lengths += rs_length;

   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;

   _inc_cset_bytes_used_before += used_bytes;

   // Cache the values we have added to the aggregated informtion

   // in the heap region in case we have to remove this region from

   // the incremental collection set, or it is updated by the

   // rset sampling code

   hr->set_recorded_rs_length(rs_length);

   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);

 }

 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,

                                                      size_t new_rs_length) {

   // Update the CSet information that is dependent on the new RS length

   assert(hr->is_young(), "Precondition");

   assert(!SafepointSynchronize::is_at_safepoint(),

                                                "should not be at a safepoint");

   // We could have updated _inc_cset_recorded_rs_lengths and

   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do

   // that atomically, as this code is executed by a concurrent

   // refinement thread, potentially concurrently with a mutator thread

   // allocating a new region and also updating the same fields. To

   // avoid the atomic operations we accumulate these updates on two

   // separate fields (*_diffs) and we'll just add them to the "main"

   // fields at the start of a GC.

   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();

   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;

   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;

   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();

   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());

   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;

   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;

   hr->set_recorded_rs_length(new_rs_length);

   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);

 }

 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {

   assert(hr->is_young(), "invariant");

   assert(hr->young_index_in_cset() > -1, "should have already been set");

   assert(_inc_cset_build_state == Active, "Precondition");

   // We need to clear and set the cached recorded/cached collection set

   // information in the heap region here (before the region gets added

   // to the collection set). An individual heap region's cached values

   // are calculated, aggregated with the policy collection set info,

   // and cached in the heap region here (initially) and (subsequently)

   // by the Young List sampling code.

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

   add_to_incremental_cset_info(hr, rs_length);

   HeapWord* hr_end = hr->end();

   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);

   assert(!hr->in_collection_set(), "invariant");

   hr->set_in_collection_set(true);

   assert( hr->next_in_collection_set() == NULL, "invariant");

   _g1->register_region_with_in_cset_fast_test(hr);

 }

 // Add the region at the RHS of the incremental cset

 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {

   // We should only ever be appending survivors at the end of a pause

   assert(hr->is_survivor(), "Logic");

   // Do the 'common' stuff

   add_region_to_incremental_cset_common(hr);

   // Now add the region at the right hand side

   if (_inc_cset_tail == NULL) {

     assert(_inc_cset_head == NULL, "invariant");

     _inc_cset_head = hr;

   } else {

     _inc_cset_tail->set_next_in_collection_set(hr);

   }

   _inc_cset_tail = hr;

 }

 // Add the region to the LHS of the incremental cset

 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {

   // Survivors should be added to the RHS at the end of a pause

   assert(hr->is_eden(), "Logic");

   // Do the 'common' stuff

   add_region_to_incremental_cset_common(hr);

   // Add the region at the left hand side

   hr->set_next_in_collection_set(_inc_cset_head);

   if (_inc_cset_head == NULL) {

     assert(_inc_cset_tail == NULL, "Invariant");

     _inc_cset_tail = hr;

   }

   _inc_cset_head = hr;

 }

 #ifndef PRODUCT

 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {

   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");

   st->print_cr("\nCollection_set:");

   HeapRegion* csr = list_head;

   while (csr != NULL) {

     HeapRegion* next = csr->next_in_collection_set();

     assert(csr->in_collection_set(), "bad CS");

     st->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",

                  HR_FORMAT_PARAMS(csr),

                  csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),

                  csr->age_in_surv_rate_group_cond());

     csr = next;

   }

 }

 #endif // !PRODUCT

 double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {

   // Returns the given amount of reclaimable bytes (that represents

   // the amount of reclaimable space still to be collected) as a

   // percentage of the current heap capacity.

   size_t capacity_bytes = _g1->capacity();

   return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;

 }

 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,

                                                 const char* false_action_str) {

   CollectionSetChooser* cset_chooser = _collectionSetChooser;

   if (cset_chooser->is_empty()) {

     ergo_verbose0(ErgoMixedGCs,

                   false_action_str,

                   ergo_format_reason("candidate old regions not available"));

     return false;

   }

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

   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();

   double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);

   double threshold = (double) G1HeapWastePercent;

   if (reclaimable_perc <= threshold) {

     ergo_verbose4(ErgoMixedGCs,

               false_action_str,

               ergo_format_reason("reclaimable percentage not over threshold")

               ergo_format_region("candidate old regions")

               ergo_format_byte_perc("reclaimable")

               ergo_format_perc("threshold"),

               cset_chooser->remaining_regions(),

               reclaimable_bytes,

               reclaimable_perc, threshold);

     return false;

   }

   ergo_verbose4(ErgoMixedGCs,

                 true_action_str,

                 ergo_format_reason("candidate old regions available")

                 ergo_format_region("candidate old regions")

                 ergo_format_byte_perc("reclaimable")

                 ergo_format_perc("threshold"),

                 cset_chooser->remaining_regions(),

                 reclaimable_bytes,

                 reclaimable_perc, threshold);

   return true;

 }

 uint G1CollectorPolicy::calc_min_old_cset_length() {

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

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

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

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

   // maximum desired number of mixed GCs.

   //

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

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

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

   const size_t region_num = (size_t) _collectionSetChooser->length();

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

   size_t result = region_num / gc_num;

   // emulate ceiling

   if (result * gc_num < region_num) {

     result += 1;

   }

   return (uint) result;

 }

 uint G1CollectorPolicy::calc_max_old_cset_length() {

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

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

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

   // of them are available.

   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   const size_t region_num = g1h->num_regions();

   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;

   size_t result = region_num * perc / 100;

   // emulate ceiling

   if (100 * result < region_num * perc) {

     result += 1;

   }

   return (uint) result;

 }

 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms, EvacuationInfo& evacuation_info) {

   double young_start_time_sec = os::elapsedTime();

   YoungList* young_list = _g1->young_list();

   finalize_incremental_cset_building();

   guarantee(target_pause_time_ms > 0.0,

             err_msg("target_pause_time_ms = %1.6lf should be positive",

                     target_pause_time_ms));

   guarantee(_collection_set == NULL, "Precondition");

   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);

   double predicted_pause_time_ms = base_time_ms;

   double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);

   ergo_verbose4(ErgoCSetConstruction | ErgoHigh,

                 "start choosing CSet",

                 ergo_format_size("_pending_cards")

                 ergo_format_ms("predicted base time")

                 ergo_format_ms("remaining time")

                 ergo_format_ms("target pause time"),

                 _pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);

   _last_gc_was_young = gcs_are_young() ? true : false;

   if (_last_gc_was_young) {

     _trace_gen0_time_data.increment_young_collection_count();

   } else {

     _trace_gen0_time_data.increment_mixed_collection_count();

   }

   // The young list is laid with the survivor regions from the previous

   // pause are appended to the RHS of the young list, i.e.

   //   [Newly Young Regions ++ Survivors from last pause].

   uint survivor_region_length = young_list->survivor_length();

   uint eden_region_length = young_list->length() - survivor_region_length;

   init_cset_region_lengths(eden_region_length, survivor_region_length);

   HeapRegion* hr = young_list->first_survivor_region();

   while (hr != NULL) {

     assert(hr->is_survivor(), "badly formed young list");

     // There is a convention that all the young regions in the CSet

     // are tagged as "eden", so we do this for the survivors here. We

     // use the special set_eden_pre_gc() as it doesn't check that the

     // region is free (which is not the case here).

     hr->set_eden_pre_gc();

     hr = hr->get_next_young_region();

   }

   // Clear the fields that point to the survivor list - they are all young now.

   young_list->clear_survivors();

   _collection_set = _inc_cset_head;

   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;

   time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);

   predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;

   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,

                 "add young regions to CSet",

                 ergo_format_region("eden")

                 ergo_format_region("survivors")

                 ergo_format_ms("predicted young region time"),

                 eden_region_length, survivor_region_length,

                 _inc_cset_predicted_elapsed_time_ms);

   // The number of recorded young regions is the incremental

   // collection set's current size

   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);

   double young_end_time_sec = os::elapsedTime();

   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);

   // Set the start of the non-young choice time.

   double non_young_start_time_sec = young_end_time_sec;

   if (!gcs_are_young()) {

     CollectionSetChooser* cset_chooser = _collectionSetChooser;

     cset_chooser->verify();

     const uint min_old_cset_length = calc_min_old_cset_length();

     const uint max_old_cset_length = calc_max_old_cset_length();

     uint expensive_region_num = 0;

     bool check_time_remaining = adaptive_young_list_length();

     HeapRegion* hr = cset_chooser->peek();

     while (hr != NULL) {

       if (old_cset_region_length() >= max_old_cset_length) {

         // Added maximum number of old regions to the CSet.

         ergo_verbose2(ErgoCSetConstruction,

                       "finish adding old regions to CSet",

                       ergo_format_reason("old CSet region num reached max")

                       ergo_format_region("old")

                       ergo_format_region("max"),

                       old_cset_region_length(), max_old_cset_length);

         break;

       }

       // Stop adding regions if the remaining reclaimable space is

       // not above G1HeapWastePercent.

       size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();

       double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);

       double threshold = (double) G1HeapWastePercent;

       if (reclaimable_perc <= threshold) {

         // We've added enough old regions that the amount of uncollected

         // reclaimable space is at or below the waste threshold. Stop

         // adding old regions to the CSet.

         ergo_verbose5(ErgoCSetConstruction,

                       "finish adding old regions to CSet",

                       ergo_format_reason("reclaimable percentage not over threshold")

                       ergo_format_region("old")

                       ergo_format_region("max")

                       ergo_format_byte_perc("reclaimable")

                       ergo_format_perc("threshold"),

                       old_cset_region_length(),

                       max_old_cset_length,

                       reclaimable_bytes,

                       reclaimable_perc, threshold);

         break;

       }

       double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());

       if (check_time_remaining) {

         if (predicted_time_ms > time_remaining_ms) {

           // Too expensive for the current CSet.

           if (old_cset_region_length() >= min_old_cset_length) {

             // We have added the minimum number of old regions to the CSet,

             // we are done with this CSet.

             ergo_verbose4(ErgoCSetConstruction,

                           "finish adding old regions to CSet",

                           ergo_format_reason("predicted time is too high")

                           ergo_format_ms("predicted time")

                           ergo_format_ms("remaining time")

                           ergo_format_region("old")

                           ergo_format_region("min"),

                           predicted_time_ms, time_remaining_ms,

                           old_cset_region_length(), min_old_cset_length);

             break;

           }

           // We'll add it anyway given that we haven't reached the

           // minimum number of old regions.

           expensive_region_num += 1;

         }

       } else {

         if (old_cset_region_length() >= min_old_cset_length) {

           // In the non-auto-tuning case, we'll finish adding regions

           // to the CSet if we reach the minimum.

           ergo_verbose2(ErgoCSetConstruction,

                         "finish adding old regions to CSet",

                         ergo_format_reason("old CSet region num reached min")

                         ergo_format_region("old")

                         ergo_format_region("min"),

                         old_cset_region_length(), min_old_cset_length);

           break;

         }

       }

       // We will add this region to the CSet.

       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);

       predicted_pause_time_ms += predicted_time_ms;

       cset_chooser->remove_and_move_to_next(hr);

       _g1->old_set_remove(hr);

       add_old_region_to_cset(hr);

       hr = cset_chooser->peek();

     }

     if (hr == NULL) {

       ergo_verbose0(ErgoCSetConstruction,

                     "finish adding old regions to CSet",

                     ergo_format_reason("candidate old regions not available"));

     }

     if (expensive_region_num > 0) {

       // We print the information once here at the end, predicated on

       // whether we added any apparently expensive regions or not, to

       // avoid generating output per region.

       ergo_verbose4(ErgoCSetConstruction,

                     "added expensive regions to CSet",

                     ergo_format_reason("old CSet region num not reached min")

                     ergo_format_region("old")

                     ergo_format_region("expensive")

                     ergo_format_region("min")

                     ergo_format_ms("remaining time"),

                     old_cset_region_length(),

                     expensive_region_num,

                     min_old_cset_length,

                     time_remaining_ms);

     }

     cset_chooser->verify();

   }

   stop_incremental_cset_building();

   ergo_verbose5(ErgoCSetConstruction,

                 "finish choosing CSet",

                 ergo_format_region("eden")

                 ergo_format_region("survivors")

                 ergo_format_region("old")

                 ergo_format_ms("predicted pause time")

                 ergo_format_ms("target pause time"),

                 eden_region_length, survivor_region_length,

                 old_cset_region_length(),

                 predicted_pause_time_ms, target_pause_time_ms);

   double non_young_end_time_sec = os::elapsedTime();

   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);

   evacuation_info.set_collectionset_regions(cset_region_length());

 }

 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {

   if(TraceGen0Time) {

     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);

   }

 }

 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {

   if(TraceGen0Time) {

     _all_yield_times_ms.add(yield_time_ms);

   }

 }

 void TraceGen0TimeData::record_end_collection(double pause_time_ms, G1GCPhaseTimes* phase_times) {

   if(TraceGen0Time) {

     _total.add(pause_time_ms);

     _other.add(pause_time_ms - phase_times->accounted_time_ms());

     _root_region_scan_wait.add(phase_times->root_region_scan_wait_time_ms());

     _parallel.add(phase_times->cur_collection_par_time_ms());

     _ext_root_scan.add(phase_times->average_last_ext_root_scan_time());

     _satb_filtering.add(phase_times->average_last_satb_filtering_times_ms());

     _update_rs.add(phase_times->average_last_update_rs_time());

     _scan_rs.add(phase_times->average_last_scan_rs_time());

     _obj_copy.add(phase_times->average_last_obj_copy_time());

     _termination.add(phase_times->average_last_termination_time());

     double parallel_known_time = phase_times->average_last_ext_root_scan_time() +

       phase_times->average_last_satb_filtering_times_ms() +

       phase_times->average_last_update_rs_time() +

       phase_times->average_last_scan_rs_time() +

       phase_times->average_last_obj_copy_time() +

       + phase_times->average_last_termination_time();

     double parallel_other_time = phase_times->cur_collection_par_time_ms() - parallel_known_time;

     _parallel_other.add(parallel_other_time);

     _clear_ct.add(phase_times->cur_clear_ct_time_ms());

   }

 }

 void TraceGen0TimeData::increment_young_collection_count() {

   if(TraceGen0Time) {

     ++_young_pause_num;

   }

 }

 void TraceGen0TimeData::increment_mixed_collection_count() {

   if(TraceGen0Time) {

     ++_mixed_pause_num;

   }

 }

 void TraceGen0TimeData::print_summary(const char* str,

                                       const NumberSeq* seq) const {

   double sum = seq->sum();

   gclog_or_tty->print_cr("%-27s = %8.2lf s (avg = %8.2lf ms)",

                 str, sum / 1000.0, seq->avg());

 }

 void TraceGen0TimeData::print_summary_sd(const char* str,

                                          const NumberSeq* seq) const {

   print_summary(str, seq);

   gclog_or_tty->print_cr("%+45s = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",

                 "(num", seq->num(), seq->sd(), seq->maximum());

 }

 void TraceGen0TimeData::print() const {

   if (!TraceGen0Time) {

     return;

   }

   gclog_or_tty->print_cr("ALL PAUSES");

   print_summary_sd("   Total", &_total);

   gclog_or_tty->cr();

   gclog_or_tty->cr();

   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);

   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);

   gclog_or_tty->cr();

   gclog_or_tty->print_cr("EVACUATION PAUSES");

   if (_young_pause_num == 0 && _mixed_pause_num == 0) {

     gclog_or_tty->print_cr("none");

   } else {

     print_summary_sd("   Evacuation Pauses", &_total);

     print_summary("      Root Region Scan Wait", &_root_region_scan_wait);

     print_summary("      Parallel Time", &_parallel);

     print_summary("         Ext Root Scanning", &_ext_root_scan);

     print_summary("         SATB Filtering", &_satb_filtering);

     print_summary("         Update RS", &_update_rs);

     print_summary("         Scan RS", &_scan_rs);

     print_summary("         Object Copy", &_obj_copy);

     print_summary("         Termination", &_termination);

     print_summary("         Parallel Other", &_parallel_other);

     print_summary("      Clear CT", &_clear_ct);

     print_summary("      Other", &_other);

   }

   gclog_or_tty->cr();

   gclog_or_tty->print_cr("MISC");

   print_summary_sd("   Stop World", &_all_stop_world_times_ms);

   print_summary_sd("   Yields", &_all_yield_times_ms);

 }

 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {

   if (TraceGen1Time) {

     _all_full_gc_times.add(full_gc_time_ms);

   }

 }

 void TraceGen1TimeData::print() const {

   if (!TraceGen1Time) {

     return;

   }

   if (_all_full_gc_times.num() > 0) {

     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",

       _all_full_gc_times.num(),

       _all_full_gc_times.sum() / 1000.0);

     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());

     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",

       _all_full_gc_times.sd(),

       _all_full_gc_times.maximum());

   }

 }