jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@a248d0be1309 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@a248d0be1309 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp

Mon, 19 Aug 2019 10:11:31 +0200

author: neugens
date: Mon, 19 Aug 2019 10:11:31 +0200
changeset 9861: a248d0be1309
parent 9858: b985cbb00e68
child 9896: 1b8c45b8216a
permissions: -rw-r--r--

8229401: Fix JFR code cache test failures
8223689: Add JFR Thread Sampling Support
8223690: Add JFR BiasedLock Event Support
8223691: Add JFR G1 Region Type Change Event Support
8223692: Add JFR G1 Heap Summary Event Support
Summary: Backport JFR from JDK11, additional fixes
Reviewed-by: neugens, apetushkov
Contributed-by: denghui.ddh@alibaba-inc.com

 /*
  * 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.
  *
  */
 #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
 };
 static double cost_per_card_ms_defaults[] = {
 .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[] = {
 .0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
 };
 static double cost_per_entry_ms_defaults[] = {
 .015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
 };
 static double cost_per_byte_ms_defaults[] = {
 .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[] = {
 .0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
 };
 static double young_other_cost_per_region_ms_defaults[] = {
 .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[] = {
 .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),
 U);
     if (FLAG_IS_CMDLINE(MaxNewSize)) {
       _max_desired_young_length =
                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
 U);
       _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),
 U);
     _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, GCTracer &tracer) {
   // 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(tracer);
   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_time_ms(G1GCPhaseTimes::UpdateRS) / (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_time_ms(G1GCPhaseTimes::ScanRS) / (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_time_ms(G1GCPhaseTimes::ObjCopy) / (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_time_ms(G1GCPhaseTimes::UpdateRS) + phase_times()->average_time_ms(G1GCPhaseTimes::ScanRS) +
           phase_times()->average_time_ms(G1GCPhaseTimes::ObjCopy) + phase_times()->average_time_ms(G1GCPhaseTimes::Termination));
     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_time_ms(G1GCPhaseTimes::UpdateRS),
                                phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS), 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;
 }
 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(GCTracer &tracer) {
   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, tracer);
 }
 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_old_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_young_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_time_ms(G1GCPhaseTimes::ExtRootScan));
     _satb_filtering.add(phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering));
     _update_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS));
     _scan_rs.add(phase_times->average_time_ms(G1GCPhaseTimes::ScanRS));
     _obj_copy.add(phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy));
     _termination.add(phase_times->average_time_ms(G1GCPhaseTimes::Termination));
     double parallel_known_time = phase_times->average_time_ms(G1GCPhaseTimes::ExtRootScan) +
       phase_times->average_time_ms(G1GCPhaseTimes::SATBFiltering) +
       phase_times->average_time_ms(G1GCPhaseTimes::UpdateRS) +
       phase_times->average_time_ms(G1GCPhaseTimes::ScanRS) +
       phase_times->average_time_ms(G1GCPhaseTimes::ObjCopy) +
       phase_times->average_time_ms(G1GCPhaseTimes::Termination);
     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());
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@a248d0be1309 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp