view src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp @ 2740:4dfb2df418f2

6484982: G1: process references during evacuation pauses Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate. Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp
author johnc
date Thu, 22 Sep 2011 10:57:37 -0700
parents d912b598c6c3
children 273b46400613
line wrap: on
line source
/*
 * Copyright (c) 2001, 2011, 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.
 *
 */

#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/heapRegionRemSet.hpp"
#include "gc_implementation/shared/gcPolicyCounters.hpp"
#include "runtime/arguments.hpp"
#include "runtime/java.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/debug.hpp"

#define PREDICTIONS_VERBOSE 0

// <NEW PREDICTION>

// Different defaults for different number of GC threads
// They were chosen by running GCOld and SPECjbb on debris with different
//   numbers of GC threads and choosing them based on the results

// all the same
static double rs_length_diff_defaults[] = {
  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
};

static double cost_per_card_ms_defaults[] = {
  0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
};

// all the same
static double fully_young_cards_per_entry_ratio_defaults[] = {
  1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
};

static double cost_per_entry_ms_defaults[] = {
  0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
};

static double cost_per_byte_ms_defaults[] = {
  0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
};

// these should be pretty consistent
static double constant_other_time_ms_defaults[] = {
  5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
};


static double young_other_cost_per_region_ms_defaults[] = {
  0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
};

static double non_young_other_cost_per_region_ms_defaults[] = {
  1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
};

// </NEW PREDICTION>

// Help class for avoiding interleaved logging
class LineBuffer: public StackObj {

private:
  static const int BUFFER_LEN = 1024;
  static const int INDENT_CHARS = 3;
  char _buffer[BUFFER_LEN];
  int _indent_level;
  int _cur;

  void vappend(const char* format, va_list ap) {
    int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
    if (res != -1) {
      _cur += res;
    } else {
      DEBUG_ONLY(warning("buffer too small in LineBuffer");)
      _buffer[BUFFER_LEN -1] = 0;
      _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
    }
  }

public:
  explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
    for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
      _buffer[_cur] = ' ';
    }
  }

#ifndef PRODUCT
  ~LineBuffer() {
    assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
  }
#endif

  void append(const char* format, ...) {
    va_list ap;
    va_start(ap, format);
    vappend(format, ap);
    va_end(ap);
  }

  void append_and_print_cr(const char* format, ...) {
    va_list ap;
    va_start(ap, format);
    vappend(format, ap);
    va_end(ap);
    gclog_or_tty->print_cr("%s", _buffer);
    _cur = _indent_level * INDENT_CHARS;
  }
};

G1CollectorPolicy::G1CollectorPolicy() :
  _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
                        ? ParallelGCThreads : 1),

  _n_pauses(0),
  _recent_rs_scan_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _all_pause_times_ms(new NumberSeq()),
  _stop_world_start(0.0),
  _all_stop_world_times_ms(new NumberSeq()),
  _all_yield_times_ms(new NumberSeq()),
  _using_new_ratio_calculations(false),

  _all_mod_union_times_ms(new NumberSeq()),

  _summary(new Summary()),

  _cur_clear_ct_time_ms(0.0),

  _cur_ref_proc_time_ms(0.0),
  _cur_ref_enq_time_ms(0.0),

#ifndef PRODUCT
  _min_clear_cc_time_ms(-1.0),
  _max_clear_cc_time_ms(-1.0),
  _cur_clear_cc_time_ms(0.0),
  _cum_clear_cc_time_ms(0.0),
  _num_cc_clears(0L),
#endif

  _region_num_young(0),
  _region_num_tenured(0),
  _prev_region_num_young(0),
  _prev_region_num_tenured(0),

  _aux_num(10),
  _all_aux_times_ms(new NumberSeq[_aux_num]),
  _cur_aux_start_times_ms(new double[_aux_num]),
  _cur_aux_times_ms(new double[_aux_num]),
  _cur_aux_times_set(new bool[_aux_num]),

  _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

  // <NEW PREDICTION>

  _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  _prev_collection_pause_end_ms(0.0),
  _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
  _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
  _partially_young_cards_per_entry_ratio_seq(
                                         new TruncatedSeq(TruncatedSeqLength)),
  _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
  _partially_young_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)),
  _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
  _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),

  _pause_time_target_ms((double) MaxGCPauseMillis),

  // </NEW PREDICTION>

  _full_young_gcs(true),
  _full_young_pause_num(0),
  _partial_young_pause_num(0),

  _during_marking(false),
  _in_marking_window(false),
  _in_marking_window_im(false),

  _known_garbage_ratio(0.0),
  _known_garbage_bytes(0),

  _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),

   _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),

  _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
  _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),

  _recent_avg_pause_time_ratio(0.0),
  _num_markings(0),
  _n_marks(0),
  _n_pauses_at_mark_end(0),

  _all_full_gc_times_ms(new NumberSeq()),

  // G1PausesBtwnConcMark defaults to -1
  // so the hack is to do the cast  QQQ FIXME
  _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
  _n_marks_since_last_pause(0),
  _initiate_conc_mark_if_possible(false),
  _during_initial_mark_pause(false),
  _should_revert_to_full_young_gcs(false),
  _last_full_young_gc(false),

  _eden_bytes_before_gc(0),
  _survivor_bytes_before_gc(0),
  _capacity_before_gc(0),

  _prev_collection_pause_used_at_end_bytes(0),

  _collection_set(NULL),
  _collection_set_size(0),
  _collection_set_bytes_used_before(0),

  // Incremental CSet attributes
  _inc_cset_build_state(Inactive),
  _inc_cset_head(NULL),
  _inc_cset_tail(NULL),
  _inc_cset_size(0),
  _inc_cset_young_index(0),
  _inc_cset_bytes_used_before(0),
  _inc_cset_max_finger(NULL),
  _inc_cset_recorded_young_bytes(0),
  _inc_cset_recorded_rs_lengths(0),
  _inc_cset_predicted_elapsed_time_ms(0.0),
  _inc_cset_predicted_bytes_to_copy(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.
  HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
  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 uint region_size = HeapRegion::GrainWords;
  if (YoungPLABSize > region_size || OldPLABSize > region_size) {
    char buffer[128];
    jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
                 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;

  _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
  _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
  _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];

  _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
  _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];

  _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];

  _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];

  _par_last_termination_times_ms = new double[_parallel_gc_threads];
  _par_last_termination_attempts = new double[_parallel_gc_threads];
  _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
  _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];

  // start conservatively
  _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;

  // <NEW PREDICTION>

  int index;
  if (ParallelGCThreads == 0)
    index = 0;
  else if (ParallelGCThreads > 8)
    index = 7;
  else
    index = ParallelGCThreads - 1;

  _pending_card_diff_seq->add(0.0);
  _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
  _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
  _fully_young_cards_per_entry_ratio_seq->add(
                            fully_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]);

  // </NEW PREDICTION>

  // 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);
  _sigma = (double) G1ConfidencePercent / 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;

  initialize_all();
}

// Increment "i", mod "len"
static void inc_mod(int& i, int len) {
  i++; if (i == len) i = 0;
}

void G1CollectorPolicy::initialize_flags() {
  set_min_alignment(HeapRegion::GrainBytes);
  set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
  if (SurvivorRatio < 1) {
    vm_exit_during_initialization("Invalid survivor ratio specified");
  }
  CollectorPolicy::initialize_flags();
}

// The easiest way to deal with the parsing of the NewSize /
// MaxNewSize / etc. parameteres is to re-use the code in the
// TwoGenerationCollectorPolicy class. This is similar to what
// ParallelScavenge does with its GenerationSizer class (see
// ParallelScavengeHeap::initialize()). We might change this in the
// future, but it's a good start.
class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
private:
  size_t size_to_region_num(size_t byte_size) {
    return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
  }

public:
  G1YoungGenSizer() {
    initialize_flags();
    initialize_size_info();
  }
  size_t min_young_region_num() {
    return size_to_region_num(_min_gen0_size);
  }
  size_t initial_young_region_num() {
    return size_to_region_num(_initial_gen0_size);
  }
  size_t max_young_region_num() {
    return size_to_region_num(_max_gen0_size);
  }
};

void G1CollectorPolicy::update_young_list_size_using_newratio(size_t number_of_heap_regions) {
  assert(number_of_heap_regions > 0, "Heap must be initialized");
  size_t young_size = number_of_heap_regions / (NewRatio + 1);
  _min_desired_young_length = young_size;
  _max_desired_young_length = young_size;
}

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();

  G1YoungGenSizer sizer;
  size_t initial_region_num = sizer.initial_young_region_num();
  _min_desired_young_length = sizer.min_young_region_num();
  _max_desired_young_length = sizer.max_young_region_num();

  if (FLAG_IS_CMDLINE(NewRatio)) {
    if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
      warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
    } else {
      // Treat NewRatio as a fixed size that is only recalculated when the heap size changes
      update_young_list_size_using_newratio(_g1->n_regions());
      _using_new_ratio_calculations = true;
    }
  }

  // GenCollectorPolicy guarantees that min <= initial <= max.
  // Asserting here just to state that we rely on this property.
  assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
  assert(initial_region_num <= _max_desired_young_length, "Initial young gen size too large");
  assert(_min_desired_young_length <= initial_region_num, "Initial young gen size too small");

  set_adaptive_young_list_length(_min_desired_young_length < _max_desired_young_length);
  if (adaptive_young_list_length()) {
    _young_list_fixed_length = 0;
  } else {
    _young_list_fixed_length = initial_region_num;
  }
  _free_regions_at_end_of_collection = _g1->free_regions();
  update_young_list_target_length();
  _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;

  // 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(size_t young_length,
                                         double base_time_ms,
                                         size_t 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(size_t 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 = (size_t) ceil(reserve_regions_d);

  if (_using_new_ratio_calculations) {
    // -XX:NewRatio was specified so we need to update the
    // young gen length when the heap size has changed.
    update_young_list_size_using_newratio(new_number_of_regions);
  }
}

size_t G1CollectorPolicy::calculate_young_list_desired_min_length(
                                                     size_t base_min_length) {
  size_t 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 = (size_t) 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(_min_desired_young_length, desired_min_length);
}

size_t 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 _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).
  size_t 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.
  size_t absolute_min_length = base_min_length + 1;
  size_t 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.
  size_t absolute_max_length = 0;
  if (_free_regions_at_end_of_collection > _reserve_regions) {
    absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
  }
  size_t desired_max_length = calculate_young_list_desired_max_length();
  if (desired_max_length > absolute_max_length) {
    desired_max_length = absolute_max_length;
  }

  size_t young_list_target_length = 0;
  if (adaptive_young_list_length()) {
    if (full_young_gcs()) {
      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 {
    if (full_young_gcs()) {
      young_list_target_length = _young_list_fixed_length;
    } else {
      // A bit arbitrary: during partially-young GCs we allocate half
      // the young regions to try to add old regions to the CSet.
      young_list_target_length = _young_list_fixed_length / 2;
      // We choose to accept that we might go under the desired min
      // length given that we intentionally ask for a smaller young gen.
      desired_min_length = absolute_min_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();
}

size_t
G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
                                                   size_t base_min_length,
                                                   size_t desired_min_length,
                                                   size_t desired_max_length) {
  assert(adaptive_young_list_length(), "pre-condition");
  assert(full_young_gcs(), "only call this for fully-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");
  size_t min_young_length = desired_min_length - base_min_length;
  assert(desired_max_length > base_min_length, "invariant");
  size_t 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;
  size_t available_free_regions = _free_regions_at_end_of_collection;
  size_t 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");
      size_t diff = (max_young_length - min_young_length) / 2;
      while (diff > 0) {
        size_t 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, true);
  }
  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() {
  _cur_collection_start_sec = os::elapsedTime();
  // 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 - _cur_collection_start_sec;
  double full_gc_time_ms = full_gc_time_sec * 1000.0;

  _all_full_gc_times_ms->add(full_gc_time_ms);

  update_recent_gc_times(end_sec, full_gc_time_ms);

  _g1->clear_full_collection();

  // "Nuke" the heuristics that control the fully/partially young GC
  // transitions and make sure we start with fully young GCs after the
  // Full GC.
  set_full_young_gcs(true);
  _last_full_young_gc = false;
  _should_revert_to_full_young_gcs = false;
  clear_initiate_conc_mark_if_possible();
  clear_during_initial_mark_pause();
  _known_garbage_bytes = 0;
  _known_garbage_ratio = 0.0;
  _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);

  _prev_region_num_young   = _region_num_young;
  _prev_region_num_tenured = _region_num_tenured;

  _free_regions_at_end_of_collection = _g1->free_regions();
  // Reset survivors SurvRateGroup.
  _survivor_surv_rate_group->reset();
  update_young_list_target_length();
}

void G1CollectorPolicy::record_stop_world_start() {
  _stop_world_start = os::elapsedTime();
}

void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
                                                      size_t start_used) {
  if (PrintGCDetails) {
    gclog_or_tty->stamp(PrintGCTimeStamps);
    gclog_or_tty->print("[GC pause");
    gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
  }

  // We only need to do this here as the policy will only be applied
  // to the GC we're about to start. so, no point is calculating this
  // every time we calculate / recalculate the target young length.
  update_survivors_policy();

  assert(_g1->used() == _g1->recalculate_used(),
         err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
                 _g1->used(), _g1->recalculate_used()));

  double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
  _all_stop_world_times_ms->add(s_w_t_ms);
  _stop_world_start = 0.0;

  _cur_collection_start_sec = start_time_sec;
  _cur_collection_pause_used_at_start_bytes = start_used;
  _cur_collection_pause_used_regions_at_start = _g1->used_regions();
  _pending_cards = _g1->pending_card_num();
  _max_pending_cards = _g1->max_pending_card_num();

  _bytes_in_collection_set_before_gc = 0;
  _bytes_copied_during_gc = 0;

  YoungList* young_list = _g1->young_list();
  _eden_bytes_before_gc = young_list->eden_used_bytes();
  _survivor_bytes_before_gc = young_list->survivor_used_bytes();
  _capacity_before_gc = _g1->capacity();

#ifdef DEBUG
  // initialise these to something well known so that we can spot
  // if they are not set properly

  for (int i = 0; i < _parallel_gc_threads; ++i) {
    _par_last_gc_worker_start_times_ms[i] = -1234.0;
    _par_last_ext_root_scan_times_ms[i] = -1234.0;
    _par_last_mark_stack_scan_times_ms[i] = -1234.0;
    _par_last_update_rs_times_ms[i] = -1234.0;
    _par_last_update_rs_processed_buffers[i] = -1234.0;
    _par_last_scan_rs_times_ms[i] = -1234.0;
    _par_last_obj_copy_times_ms[i] = -1234.0;
    _par_last_termination_times_ms[i] = -1234.0;
    _par_last_termination_attempts[i] = -1234.0;
    _par_last_gc_worker_end_times_ms[i] = -1234.0;
    _par_last_gc_worker_times_ms[i] = -1234.0;
  }
#endif

  for (int i = 0; i < _aux_num; ++i) {
    _cur_aux_times_ms[i] = 0.0;
    _cur_aux_times_set[i] = false;
  }

  _satb_drain_time_set = false;
  _last_satb_drain_processed_buffers = -1;

  _last_young_gc_full = 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_mark_closure_time(double mark_closure_time_ms) {
  _mark_closure_time_ms = mark_closure_time_ms;
}

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_end(size_t freed_bytes,
                                                      size_t max_live_bytes) {
  record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  record_concurrent_mark_cleanup_end_work2();
}

void
G1CollectorPolicy::
record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
                                         size_t max_live_bytes) {
  if (_n_marks < 2) {
    _n_marks++;
  }
}

// The important thing about this is that it includes "os::elapsedTime".
void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
  double end_time_sec = os::elapsedTime();
  double elapsed_time_ms = (end_time_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_time_sec, true);

  _num_markings++;
  _n_pauses_at_mark_end = _n_pauses;
  _n_marks_since_last_pause++;
}

void
G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
  _should_revert_to_full_young_gcs = false;
  _last_full_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;
    _all_yield_times_ms->add(yield_ms);
  }
}

void G1CollectorPolicy::record_concurrent_pause_end() {
}

template<class T>
T sum_of(T* sum_arr, int start, int n, int N) {
  T sum = (T)0;
  for (int i = 0; i < n; i++) {
    int j = (start + i) % N;
    sum += sum_arr[j];
  }
  return sum;
}

void G1CollectorPolicy::print_par_stats(int level,
                                        const char* str,
                                        double* data) {
  double min = data[0], max = data[0];
  double total = 0.0;
  LineBuffer buf(level);
  buf.append("[%s (ms):", str);
  for (uint i = 0; i < ParallelGCThreads; ++i) {
    double val = data[i];
    if (val < min)
      min = val;
    if (val > max)
      max = val;
    total += val;
    buf.append("  %3.1lf", val);
  }
  buf.append_and_print_cr("");
  double avg = total / (double) ParallelGCThreads;
  buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
    avg, min, max, max - min);
}

void G1CollectorPolicy::print_par_sizes(int level,
                                        const char* str,
                                        double* data) {
  double min = data[0], max = data[0];
  double total = 0.0;
  LineBuffer buf(level);
  buf.append("[%s :", str);
  for (uint i = 0; i < ParallelGCThreads; ++i) {
    double val = data[i];
    if (val < min)
      min = val;
    if (val > max)
      max = val;
    total += val;
    buf.append(" %d", (int) val);
  }
  buf.append_and_print_cr("");
  double avg = total / (double) ParallelGCThreads;
  buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
    (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
}

void G1CollectorPolicy::print_stats (int level,
                                     const char* str,
                                     double value) {
  LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
}

void G1CollectorPolicy::print_stats (int level,
                                     const char* str,
                                     int value) {
  LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
}

double G1CollectorPolicy::avg_value (double* data) {
  if (G1CollectedHeap::use_parallel_gc_threads()) {
    double ret = 0.0;
    for (uint i = 0; i < ParallelGCThreads; ++i)
      ret += data[i];
    return ret / (double) ParallelGCThreads;
  } else {
    return data[0];
  }
}

double G1CollectorPolicy::max_value (double* data) {
  if (G1CollectedHeap::use_parallel_gc_threads()) {
    double ret = data[0];
    for (uint i = 1; i < ParallelGCThreads; ++i)
      if (data[i] > ret)
        ret = data[i];
    return ret;
  } else {
    return data[0];
  }
}

double G1CollectorPolicy::sum_of_values (double* data) {
  if (G1CollectedHeap::use_parallel_gc_threads()) {
    double sum = 0.0;
    for (uint i = 0; i < ParallelGCThreads; i++)
      sum += data[i];
    return sum;
  } else {
    return data[0];
  }
}

double G1CollectorPolicy::max_sum (double* data1,
                                   double* data2) {
  double ret = data1[0] + data2[0];

  if (G1CollectedHeap::use_parallel_gc_threads()) {
    for (uint i = 1; i < ParallelGCThreads; ++i) {
      double data = data1[i] + data2[i];
      if (data > ret)
        ret = data;
    }
  }
  return ret;
}

// Anything below that is considered to be zero
#define MIN_TIMER_GRANULARITY 0.0000001

void G1CollectorPolicy::record_collection_pause_end() {
  double end_time_sec = os::elapsedTime();
  double elapsed_ms = _last_pause_time_ms;
  bool parallel = G1CollectedHeap::use_parallel_gc_threads();
  size_t rs_size =
    _cur_collection_pause_used_regions_at_start - collection_set_size();
  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->print_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);

  size_t marking_initiating_used_threshold =
    (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;

  if (!_g1->mark_in_progress() && !_last_full_young_gc) {
    assert(!last_pause_included_initial_mark, "invariant");
    if (cur_used_bytes > marking_initiating_used_threshold) {
      if (cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
        assert(!during_initial_mark_pause(), "we should not see this here");

        ergo_verbose3(ErgoConcCycles,
                      "request concurrent cycle initiation",
                      ergo_format_reason("occupancy higher than threshold")
                      ergo_format_byte("occupancy")
                      ergo_format_byte_perc("threshold"),
                      cur_used_bytes,
                      marking_initiating_used_threshold,
                      (double) InitiatingHeapOccupancyPercent);

        // 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();
      } else {
        ergo_verbose2(ErgoConcCycles,
                  "do not request concurrent cycle initiation",
                  ergo_format_reason("occupancy lower than previous occupancy")
                  ergo_format_byte("occupancy")
                  ergo_format_byte("previous occupancy"),
                  cur_used_bytes,
                  _prev_collection_pause_used_at_end_bytes);
      }
    }
  }

  _prev_collection_pause_used_at_end_bytes = cur_used_bytes;

  _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
                          end_time_sec, false);

  guarantee(_cur_collection_pause_used_regions_at_start >=
            collection_set_size(),
            "Negative RS size?");

  // This assert is exempted when we're doing parallel collection pauses,
  // because the fragmentation caused by the parallel GC allocation buffers
  // can lead to more memory being used during collection than was used
  // before. Best leave this out until the fragmentation problem is fixed.
  // Pauses in which evacuation failed can also lead to negative
  // collections, since no space is reclaimed from a region containing an
  // object whose evacuation failed.
  // Further, we're now always doing parallel collection.  But I'm still
  // leaving this here as a placeholder for a more precise assertion later.
  // (DLD, 10/05.)
  assert((true || parallel) // Always using GC LABs now.
         || _g1->evacuation_failed()
         || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
         "Negative collection");

  size_t freed_bytes =
    _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;

  double survival_fraction =
    (double)surviving_bytes/
    (double)_collection_set_bytes_used_before;

  _n_pauses++;

  double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  double update_rs_processed_buffers =
    sum_of_values(_par_last_update_rs_processed_buffers);
  double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  double termination_time = avg_value(_par_last_termination_times_ms);

  double parallel_known_time = update_rs_time +
                               ext_root_scan_time +
                               mark_stack_scan_time +
                               scan_rs_time +
                               obj_copy_time +
                               termination_time;

  double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;

  PauseSummary* summary = _summary;

  if (update_stats) {
    _recent_rs_scan_times_ms->add(scan_rs_time);
    _recent_pause_times_ms->add(elapsed_ms);
    _recent_rs_sizes->add(rs_size);

    MainBodySummary* body_summary = summary->main_body_summary();
    guarantee(body_summary != NULL, "should not be null!");

    if (_satb_drain_time_set)
      body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
    else
      body_summary->record_satb_drain_time_ms(0.0);

    body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
    body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
    body_summary->record_update_rs_time_ms(update_rs_time);
    body_summary->record_scan_rs_time_ms(scan_rs_time);
    body_summary->record_obj_copy_time_ms(obj_copy_time);
    if (parallel) {
      body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
      body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
      body_summary->record_termination_time_ms(termination_time);
      body_summary->record_parallel_other_time_ms(parallel_other_time);
    }
    body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);

    // We exempt parallel collection from this check because Alloc Buffer
    // fragmentation can produce negative collections.  Same with evac
    // failure.
    // Further, we're now always doing parallel collection.  But I'm still
    // leaving this here as a placeholder for a more precise assertion later.
    // (DLD, 10/05.
    assert((true || parallel)
           || _g1->evacuation_failed()
           || surviving_bytes <= _collection_set_bytes_used_before,
           "Or else negative collection!");
    _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
    _recent_CS_bytes_surviving->add(surviving_bytes);

    // this is where we update the allocation rate of the application
    double app_time_ms =
      (_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;
    }
    size_t regions_allocated =
      (_region_num_young - _prev_region_num_young) +
      (_region_num_tenured - _prev_region_num_tenured);
    double alloc_rate_ms = (double) regions_allocated / app_time_ms;
    _alloc_rate_ms_seq->add(alloc_rate_ms);
    _prev_region_num_young   = _region_num_young;
    _prev_region_num_tenured = _region_num_tenured;

    double interval_ms =
      (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
    update_recent_gc_times(end_time_sec, elapsed_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;
      }
    }
  }

  if (G1PolicyVerbose > 1) {
    gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  }

  if (G1PolicyVerbose > 1) {
    gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
                           "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
                           "      |RS|: " SIZE_FORMAT,
                           elapsed_ms, recent_avg_time_for_pauses_ms(),
                           scan_rs_time, recent_avg_time_for_rs_scan_ms(),
                           rs_size);

    gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
                           "       At end " SIZE_FORMAT "K\n"
                           "       garbage      : " SIZE_FORMAT "K"
                           "       of     " SIZE_FORMAT "K\n"
                           "       survival     : %6.2f%%  (%6.2f%% avg)",
                           _cur_collection_pause_used_at_start_bytes/K,
                           _g1->used()/K, freed_bytes/K,
                           _collection_set_bytes_used_before/K,
                           survival_fraction*100.0,
                           recent_avg_survival_fraction()*100.0);
    gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
                           recent_avg_pause_time_ratio() * 100.0);
  }

  double other_time_ms = elapsed_ms;

  if (_satb_drain_time_set) {
    other_time_ms -= _cur_satb_drain_time_ms;
  }

  if (parallel) {
    other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  } else {
    other_time_ms -=
      update_rs_time +
      ext_root_scan_time + mark_stack_scan_time +
      scan_rs_time + obj_copy_time;
  }

  if (PrintGCDetails) {
    gclog_or_tty->print_cr("%s, %1.8lf secs]",
                           (last_pause_included_initial_mark) ? " (initial-mark)" : "",
                           elapsed_ms / 1000.0);

    if (_satb_drain_time_set) {
      print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
    }
    if (_last_satb_drain_processed_buffers >= 0) {
      print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
    }
    if (parallel) {
      print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
      print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
      print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
      print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
      print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
      print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
      print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
      print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
      print_par_stats(2, "Termination", _par_last_termination_times_ms);
      print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
      print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);

      for (int i = 0; i < _parallel_gc_threads; i++) {
        _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
      }
      print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);

      print_stats(2, "Parallel Other", parallel_other_time);
      print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
    } else {
      print_stats(1, "Update RS", update_rs_time);
      print_stats(2, "Processed Buffers",
                  (int)update_rs_processed_buffers);
      print_stats(1, "Ext Root Scanning", ext_root_scan_time);
      print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
      print_stats(1, "Scan RS", scan_rs_time);
      print_stats(1, "Object Copying", obj_copy_time);
    }
#ifndef PRODUCT
    print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
    print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
    print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
    print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
    if (_num_cc_clears > 0) {
      print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
    }
#endif
    print_stats(1, "Other", other_time_ms);
    print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
    print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
    print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);

    for (int i = 0; i < _aux_num; ++i) {
      if (_cur_aux_times_set[i]) {
        char buffer[96];
        sprintf(buffer, "Aux%d", i);
        print_stats(1, buffer, _cur_aux_times_ms[i]);
      }
    }
  }

  _all_pause_times_ms->add(elapsed_ms);
  if (update_stats) {
    summary->record_total_time_ms(elapsed_ms);
    summary->record_other_time_ms(other_time_ms);
  }
  for (int i = 0; i < _aux_num; ++i)
    if (_cur_aux_times_set[i])
      _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);

  // Reset marks-between-pauses counter.
  _n_marks_since_last_pause = 0;

  // Update the efficiency-since-mark vars.
  double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  if (elapsed_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.
    proc_ms = 1.0;
  }
  double cur_efficiency = (double) freed_bytes / proc_ms;

  bool new_in_marking_window = _in_marking_window;
  bool new_in_marking_window_im = false;
  if (during_initial_mark_pause()) {
    new_in_marking_window = true;
    new_in_marking_window_im = true;
  }

  if (_last_full_young_gc) {
    ergo_verbose2(ErgoPartiallyYoungGCs,
                  "start partially-young GCs",
                  ergo_format_byte_perc("known garbage"),
                  _known_garbage_bytes, _known_garbage_ratio * 100.0);
    set_full_young_gcs(false);
    _last_full_young_gc = false;
  }

  if ( !_last_young_gc_full ) {
    if (_should_revert_to_full_young_gcs) {
      ergo_verbose2(ErgoPartiallyYoungGCs,
                    "end partially-young GCs",
                    ergo_format_reason("partially-young GCs end requested")
                    ergo_format_byte_perc("known garbage"),
                    _known_garbage_bytes, _known_garbage_ratio * 100.0);
      set_full_young_gcs(true);
    } else if (_known_garbage_ratio < 0.05) {
      ergo_verbose3(ErgoPartiallyYoungGCs,
               "end partially-young GCs",
               ergo_format_reason("known garbage percent lower than threshold")
               ergo_format_byte_perc("known garbage")
               ergo_format_perc("threshold"),
               _known_garbage_bytes, _known_garbage_ratio * 100.0,
               0.05 * 100.0);
      set_full_young_gcs(true);
    } else if (adaptive_young_list_length() &&
              (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) {
      ergo_verbose5(ErgoPartiallyYoungGCs,
                    "end partially-young GCs",
                    ergo_format_reason("current GC efficiency lower than "
                                       "predicted fully-young GC efficiency")
                    ergo_format_double("GC efficiency factor")
                    ergo_format_double("current GC efficiency")
                    ergo_format_double("predicted fully-young GC efficiency")
                    ergo_format_byte_perc("known garbage"),
                    get_gc_eff_factor(), cur_efficiency,
                    predict_young_gc_eff(),
                    _known_garbage_bytes, _known_garbage_ratio * 100.0);
      set_full_young_gcs(true);
    }
  }
  _should_revert_to_full_young_gcs = false;

  if (_last_young_gc_full && !_during_marking) {
    _young_gc_eff_seq->add(cur_efficiency);
  }

  _short_lived_surv_rate_group->start_adding_regions();
  // do that for any other surv rate groupsx

  // <NEW PREDICTION>

  if (update_stats) {
    double pause_time_ms = elapsed_ms;

    size_t diff = 0;
    if (_max_pending_cards >= _pending_cards)
      diff = _max_pending_cards - _pending_cards;
    _pending_card_diff_seq->add((double) diff);

    double cost_per_card_ms = 0.0;
    if (_pending_cards > 0) {
      cost_per_card_ms = update_rs_time / (double) _pending_cards;
      _cost_per_card_ms_seq->add(cost_per_card_ms);
    }

    size_t cards_scanned = _g1->cards_scanned();

    double cost_per_entry_ms = 0.0;
    if (cards_scanned > 10) {
      cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
      if (_last_young_gc_full)
        _cost_per_entry_ms_seq->add(cost_per_entry_ms);
      else
        _partially_young_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_young_gc_full)
        _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
      else
        _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
    }

    size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
    if (rs_length_diff >= 0)
      _rs_length_diff_seq->add((double) rs_length_diff);

    size_t copied_bytes = surviving_bytes;
    double cost_per_byte_ms = 0.0;
    if (copied_bytes > 0) {
      cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
      if (_in_marking_window)
        _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
      else
        _cost_per_byte_ms_seq->add(cost_per_byte_ms);
    }

    double all_other_time_ms = pause_time_ms -
      (update_rs_time + scan_rs_time + obj_copy_time +
       _mark_closure_time_ms + termination_time);

    double young_other_time_ms = 0.0;
    if (_recorded_young_regions > 0) {
      young_other_time_ms =
        _recorded_young_cset_choice_time_ms +
        _recorded_young_free_cset_time_ms;
      _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
                                             (double) _recorded_young_regions);
    }
    double non_young_other_time_ms = 0.0;
    if (_recorded_non_young_regions > 0) {
      non_young_other_time_ms =
        _recorded_non_young_cset_choice_time_ms +
        _recorded_non_young_free_cset_time_ms;

      _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
                                         (double) _recorded_non_young_regions);
    }

    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 (_bytes_in_collection_set_before_gc > 0) {
      survival_ratio = (double) _bytes_copied_during_gc /
                                   (double) _bytes_in_collection_set_before_gc;
    }

    _pending_cards_seq->add((double) _pending_cards);
    _scanned_cards_seq->add((double) cards_scanned);
    _rs_lengths_seq->add((double) _max_rs_lengths);

    double expensive_region_limit_ms =
      (double) MaxGCPauseMillis - predict_constant_other_time_ms();
    if (expensive_region_limit_ms < 0.0) {
      // this means that the other time was predicted to be longer than
      // than the max pause time
      expensive_region_limit_ms = (double) MaxGCPauseMillis;
    }
    _expensive_region_limit_ms = expensive_region_limit_ms;

    if (PREDICTIONS_VERBOSE) {
      gclog_or_tty->print_cr("");
      gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
                    "REGIONS %d %d %d "
                    "PENDING_CARDS %d %d "
                    "CARDS_SCANNED %d %d "
                    "RS_LENGTHS %d %d "
                    "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
                    "SURVIVAL_RATIO %1.6lf %1.6lf "
                    "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
                    "OTHER_YOUNG %1.6lf %1.6lf "
                    "OTHER_NON_YOUNG %1.6lf %1.6lf "
                    "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
                    "ELAPSED %1.6lf %1.6lf ",
                    _cur_collection_start_sec,
                    (!_last_young_gc_full) ? 2 :
                    (last_pause_included_initial_mark) ? 1 : 0,
                    _recorded_region_num,
                    _recorded_young_regions,
                    _recorded_non_young_regions,
                    _predicted_pending_cards, _pending_cards,
                    _predicted_cards_scanned, cards_scanned,
                    _predicted_rs_lengths, _max_rs_lengths,
                    _predicted_rs_update_time_ms, update_rs_time,
                    _predicted_rs_scan_time_ms, scan_rs_time,
                    _predicted_survival_ratio, survival_ratio,
                    _predicted_object_copy_time_ms, obj_copy_time,
                    _predicted_constant_other_time_ms, constant_other_time_ms,
                    _predicted_young_other_time_ms, young_other_time_ms,
                    _predicted_non_young_other_time_ms,
                    non_young_other_time_ms,
                    _vtime_diff_ms, termination_time,
                    _predicted_pause_time_ms, elapsed_ms);
    }

    if (G1PolicyVerbose > 0) {
      gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
                    _predicted_pause_time_ms,
                    (_within_target) ? "within" : "outside",
                    elapsed_ms);
    }

  }

  _in_marking_window = new_in_marking_window;
  _in_marking_window_im = new_in_marking_window_im;
  _free_regions_at_end_of_collection = _g1->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(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  // </NEW PREDICTION>
}

#define EXT_SIZE_FORMAT "%d%s"
#define EXT_SIZE_PARAMS(bytes)                                  \
  byte_size_in_proper_unit((bytes)),                            \
  proper_unit_for_byte_size((bytes))

void G1CollectorPolicy::print_heap_transition() {
  if (PrintGCDetails) {
    YoungList* young_list = _g1->young_list();
    size_t eden_bytes = young_list->eden_used_bytes();
    size_t survivor_bytes = young_list->survivor_used_bytes();
    size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
    size_t used = _g1->used();
    size_t capacity = _g1->capacity();
    size_t eden_capacity =
      (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;

    gclog_or_tty->print_cr(
      "   [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_bytes_before_gc),
      EXT_SIZE_PARAMS(_prev_eden_capacity),
      EXT_SIZE_PARAMS(eden_bytes),
      EXT_SIZE_PARAMS(eden_capacity),
      EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
      EXT_SIZE_PARAMS(survivor_bytes),
      EXT_SIZE_PARAMS(used_before_gc),
      EXT_SIZE_PARAMS(_capacity_before_gc),
      EXT_SIZE_PARAMS(used),
      EXT_SIZE_PARAMS(capacity));

    _prev_eden_capacity = eden_capacity;
  } else if (PrintGC) {
    _g1->print_size_transition(gclog_or_tty,
                               _cur_collection_pause_used_at_start_bytes,
                               _g1->used(), _g1->capacity());
  }
}

// <NEW PREDICTION>

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_young_collection_elapsed_time_ms(size_t adjustment) {
  guarantee( adjustment == 0 || adjustment == 1, "invariant" );

  G1CollectedHeap* g1h = G1CollectedHeap::heap();
  size_t young_num = g1h->young_list()->length();
  if (young_num == 0)
    return 0.0;

  young_num += adjustment;
  size_t pending_cards = predict_pending_cards();
  size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
                      predict_rs_length_diff();
  size_t card_num;
  if (full_young_gcs())
    card_num = predict_young_card_num(rs_lengths);
  else
    card_num = predict_non_young_card_num(rs_lengths);
  size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  double accum_yg_surv_rate =
    _short_lived_surv_rate_group->accum_surv_rate(adjustment);

  size_t bytes_to_copy =
    (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);

  return
    predict_rs_update_time_ms(pending_cards) +
    predict_rs_scan_time_ms(card_num) +
    predict_object_copy_time_ms(bytes_to_copy) +
    predict_young_other_time_ms(young_num) +
    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 (full_young_gcs())
    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);
}

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_region_elapsed_time_ms(HeapRegion* hr,
                                                  bool young) {
  size_t rs_length = hr->rem_set()->occupied();
  size_t card_num;
  if (full_young_gcs())
    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);

  if (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;
}

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 {
    guarantee( 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;
}

void
G1CollectorPolicy::start_recording_regions() {
  _recorded_rs_lengths            = 0;
  _recorded_young_regions         = 0;
  _recorded_non_young_regions     = 0;

#if PREDICTIONS_VERBOSE
  _recorded_marked_bytes          = 0;
  _recorded_young_bytes           = 0;
  _predicted_bytes_to_copy        = 0;
  _predicted_rs_lengths           = 0;
  _predicted_cards_scanned        = 0;
#endif // PREDICTIONS_VERBOSE
}

void
G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
#if PREDICTIONS_VERBOSE
  if (!young) {
    _recorded_marked_bytes += hr->max_live_bytes();
  }
  _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
#endif // PREDICTIONS_VERBOSE

  size_t rs_length = hr->rem_set()->occupied();
  _recorded_rs_lengths += rs_length;
}

void
G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
  assert(!hr->is_young(), "should not call this");
  ++_recorded_non_young_regions;
  record_cset_region_info(hr, false);
}

void
G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
  _recorded_young_regions = n_regions;
}

void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
#if PREDICTIONS_VERBOSE
  _recorded_young_bytes = bytes;
#endif // PREDICTIONS_VERBOSE
}

void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
  _recorded_rs_lengths = rs_lengths;
}

void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
  _predicted_bytes_to_copy = bytes;
}

void
G1CollectorPolicy::end_recording_regions() {
  // The _predicted_pause_time_ms field is referenced in code
  // not under PREDICTIONS_VERBOSE. Let's initialize it.
  _predicted_pause_time_ms = -1.0;

#if PREDICTIONS_VERBOSE
  _predicted_pending_cards = predict_pending_cards();
  _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  if (full_young_gcs())
    _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  else
    _predicted_cards_scanned +=
      predict_non_young_card_num(_predicted_rs_lengths);
  _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;

  _predicted_rs_update_time_ms =
    predict_rs_update_time_ms(_g1->pending_card_num());
  _predicted_rs_scan_time_ms =
    predict_rs_scan_time_ms(_predicted_cards_scanned);
  _predicted_object_copy_time_ms =
    predict_object_copy_time_ms(_predicted_bytes_to_copy);
  _predicted_constant_other_time_ms =
    predict_constant_other_time_ms();
  _predicted_young_other_time_ms =
    predict_young_other_time_ms(_recorded_young_regions);
  _predicted_non_young_other_time_ms =
    predict_non_young_other_time_ms(_recorded_non_young_regions);

  _predicted_pause_time_ms =
    _predicted_rs_update_time_ms +
    _predicted_rs_scan_time_ms +
    _predicted_object_copy_time_ms +
    _predicted_constant_other_time_ms +
    _predicted_young_other_time_ms +
    _predicted_non_young_other_time_ms;
#endif // PREDICTIONS_VERBOSE
}

void G1CollectorPolicy::check_if_region_is_too_expensive(double
                                                           predicted_time_ms) {
  // I don't think we need to do this when in young GC mode since
  // marking will be initiated next time we hit the soft limit anyway...
  if (predicted_time_ms > _expensive_region_limit_ms) {
    ergo_verbose2(ErgoPartiallyYoungGCs,
              "request partially-young GCs end",
              ergo_format_reason("predicted region time higher than threshold")
              ergo_format_ms("predicted region time")
              ergo_format_ms("threshold"),
              predicted_time_ms, _expensive_region_limit_ms);
    // no point in doing another partial one
    _should_revert_to_full_young_gcs = true;
  }
}

// </NEW PREDICTION>


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;
}

double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  if (_recent_pause_times_ms->num() == 0) {
    return (double) MaxGCPauseMillis;
  }
  return _recent_pause_times_ms->avg();
}

double G1CollectorPolicy::recent_avg_time_for_rs_scan_ms() {
  if (_recent_rs_scan_times_ms->num() == 0) {
    return (double)MaxGCPauseMillis/3.0;
  }
  return _recent_rs_scan_times_ms->avg();
}

int G1CollectorPolicy::number_of_recent_gcs() {
  assert(_recent_rs_scan_times_ms->num() ==
         _recent_pause_times_ms->num(), "Sequence out of sync");
  assert(_recent_pause_times_ms->num() ==
         _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  assert(_recent_CS_bytes_used_before->num() ==
         _recent_CS_bytes_surviving->num(), "Sequence out of sync");

  return _recent_pause_times_ms->num();
}

double G1CollectorPolicy::recent_avg_survival_fraction() {
  return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
                                           _recent_CS_bytes_used_before);
}

double G1CollectorPolicy::last_survival_fraction() {
  return last_survival_fraction_work(_recent_CS_bytes_surviving,
                                     _recent_CS_bytes_used_before);
}

double
G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
                                                     TruncatedSeq* before) {
  assert(surviving->num() == before->num(), "Sequence out of sync");
  if (before->sum() > 0.0) {
      double recent_survival_rate = surviving->sum() / before->sum();
      // We exempt parallel collection from this check because Alloc Buffer
      // fragmentation can produce negative collections.
      // Further, we're now always doing parallel collection.  But I'm still
      // leaving this here as a placeholder for a more precise assertion later.
      // (DLD, 10/05.)
      assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
             _g1->evacuation_failed() ||
             recent_survival_rate <= 1.0, "Or bad frac");
      return recent_survival_rate;
  } else {
    return 1.0; // Be conservative.
  }
}

double
G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
                                               TruncatedSeq* before) {
  assert(surviving->num() == before->num(), "Sequence out of sync");
  if (surviving->num() > 0 && before->last() > 0.0) {
    double last_survival_rate = surviving->last() / before->last();
    // We exempt parallel collection from this check because Alloc Buffer
    // fragmentation can produce negative collections.
    // Further, we're now always doing parallel collection.  But I'm still
    // leaving this here as a placeholder for a more precise assertion later.
    // (DLD, 10/05.)
    assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
           last_survival_rate <= 1.0, "Or bad frac");
    return last_survival_rate;
  } else {
    return 1.0;
  }
}

static const int survival_min_obs = 5;
static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
static const double min_survival_rate = 0.1;

double
G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
                                                           double latest) {
  double res = avg;
  if (number_of_recent_gcs() < survival_min_obs) {
    res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  }
  res = MAX2(res, latest);
  res = MAX2(res, min_survival_rate);
  // In the parallel case, LAB fragmentation can produce "negative
  // collections"; so can evac failure.  Cap at 1.0
  res = MIN2(res, 1.0);
  return res;
}

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::note_start_of_mark_thread() {
  _mark_thread_startup_sec = os::elapsedTime();
}

class CountCSClosure: public HeapRegionClosure {
  G1CollectorPolicy* _g1_policy;
public:
  CountCSClosure(G1CollectorPolicy* g1_policy) :
    _g1_policy(g1_policy) {}
  bool doHeapRegion(HeapRegion* r) {
    _g1_policy->_bytes_in_collection_set_before_gc += r->used();
    return false;
  }
};

void G1CollectorPolicy::count_CS_bytes_used() {
  CountCSClosure cs_closure(this);
  _g1->collection_set_iterate(&cs_closure);
}

void G1CollectorPolicy::print_summary (int level,
                                       const char* str,
                                       NumberSeq* seq) const {
  double sum = seq->sum();
  LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
                str, sum / 1000.0, seq->avg());
}

void G1CollectorPolicy::print_summary_sd (int level,
                                          const char* str,
                                          NumberSeq* seq) const {
  print_summary(level, str, seq);
  LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
                seq->num(), seq->sd(), seq->maximum());
}

void G1CollectorPolicy::check_other_times(int level,
                                        NumberSeq* other_times_ms,
                                        NumberSeq* calc_other_times_ms) const {
  bool should_print = false;
  LineBuffer buf(level + 2);

  double max_sum = MAX2(fabs(other_times_ms->sum()),
                        fabs(calc_other_times_ms->sum()));
  double min_sum = MIN2(fabs(other_times_ms->sum()),
                        fabs(calc_other_times_ms->sum()));
  double sum_ratio = max_sum / min_sum;
  if (sum_ratio > 1.1) {
    should_print = true;
    buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  }

  double max_avg = MAX2(fabs(other_times_ms->avg()),
                        fabs(calc_other_times_ms->avg()));
  double min_avg = MIN2(fabs(other_times_ms->avg()),
                        fabs(calc_other_times_ms->avg()));
  double avg_ratio = max_avg / min_avg;
  if (avg_ratio > 1.1) {
    should_print = true;
    buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  }

  if (other_times_ms->sum() < -0.01) {
    buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  }

  if (other_times_ms->avg() < -0.01) {
    buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  }

  if (calc_other_times_ms->sum() < -0.01) {
    should_print = true;
    buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  }

  if (calc_other_times_ms->avg() < -0.01) {
    should_print = true;
    buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  }

  if (should_print)
    print_summary(level, "Other(Calc)", calc_other_times_ms);
}

void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  bool parallel = G1CollectedHeap::use_parallel_gc_threads();
  MainBodySummary*    body_summary = summary->main_body_summary();
  if (summary->get_total_seq()->num() > 0) {
    print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
    if (body_summary != NULL) {
      print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
      if (parallel) {
        print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
        print_summary(2, "Update RS", body_summary->get_update_rs_seq());
        print_summary(2, "Ext Root Scanning",
                      body_summary->get_ext_root_scan_seq());
        print_summary(2, "Mark Stack Scanning",
                      body_summary->get_mark_stack_scan_seq());
        print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
        print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
        print_summary(2, "Termination", body_summary->get_termination_seq());
        print_summary(2, "Other", body_summary->get_parallel_other_seq());
        {
          NumberSeq* other_parts[] = {
            body_summary->get_update_rs_seq(),
            body_summary->get_ext_root_scan_seq(),
            body_summary->get_mark_stack_scan_seq(),
            body_summary->get_scan_rs_seq(),
            body_summary->get_obj_copy_seq(),
            body_summary->get_termination_seq()
          };
          NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
                                        6, other_parts);
          check_other_times(2, body_summary->get_parallel_other_seq(),
                            &calc_other_times_ms);
        }
        print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
        print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
      } else {
        print_summary(1, "Update RS", body_summary->get_update_rs_seq());
        print_summary(1, "Ext Root Scanning",
                      body_summary->get_ext_root_scan_seq());
        print_summary(1, "Mark Stack Scanning",
                      body_summary->get_mark_stack_scan_seq());
        print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
        print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
      }
    }
    print_summary(1, "Other", summary->get_other_seq());
    {
      if (body_summary != NULL) {
        NumberSeq calc_other_times_ms;
        if (parallel) {
          // parallel
          NumberSeq* other_parts[] = {
            body_summary->get_satb_drain_seq(),
            body_summary->get_parallel_seq(),
            body_summary->get_clear_ct_seq()
          };
          calc_other_times_ms = NumberSeq(summary->get_total_seq(),
                                                3, other_parts);
        } else {
          // serial
          NumberSeq* other_parts[] = {
            body_summary->get_satb_drain_seq(),
            body_summary->get_update_rs_seq(),
            body_summary->get_ext_root_scan_seq(),
            body_summary->get_mark_stack_scan_seq(),
            body_summary->get_scan_rs_seq(),
            body_summary->get_obj_copy_seq()
          };
          calc_other_times_ms = NumberSeq(summary->get_total_seq(),
                                                6, other_parts);
        }
        check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
      }
    }
  } else {
    LineBuffer(1).append_and_print_cr("none");
  }
  LineBuffer(0).append_and_print_cr("");
}

void G1CollectorPolicy::print_tracing_info() const {
  if (TraceGen0Time) {
    gclog_or_tty->print_cr("ALL PAUSES");
    print_summary_sd(0, "Total", _all_pause_times_ms);
    gclog_or_tty->print_cr("");
    gclog_or_tty->print_cr("");
    gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
    gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
    gclog_or_tty->print_cr("");

    gclog_or_tty->print_cr("EVACUATION PAUSES");
    print_summary(_summary);

    gclog_or_tty->print_cr("MISC");
    print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
    print_summary_sd(0, "Yields", _all_yield_times_ms);
    for (int i = 0; i < _aux_num; ++i) {
      if (_all_aux_times_ms[i].num() > 0) {
        char buffer[96];
        sprintf(buffer, "Aux%d", i);
        print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
      }
    }

    size_t all_region_num = _region_num_young + _region_num_tenured;
    gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
               "Tenured %8d (%6.2lf%%)",
               all_region_num,
               _region_num_young,
               (double) _region_num_young / (double) all_region_num * 100.0,
               _region_num_tenured,
               (double) _region_num_tenured / (double) all_region_num * 100.0);
  }
  if (TraceGen1Time) {
    if (_all_full_gc_times_ms->num() > 0) {
      gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
                 _all_full_gc_times_ms->num(),
                 _all_full_gc_times_ms->sum() / 1000.0);
      gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
      gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
                    _all_full_gc_times_ms->sd(),
                    _all_full_gc_times_ms->maximum());
    }
  }
}

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
}

void G1CollectorPolicy::update_region_num(bool young) {
  if (young) {
    ++_region_num_young;
  } else {
    ++_region_num_tenured;
  }
}

#ifndef PRODUCT
// for debugging, bit of a hack...
static char*
region_num_to_mbs(int length) {
  static char buffer[64];
  double bytes = (double) (length * HeapRegion::GrainBytes);
  double mbs = bytes / (double) (1024 * 1024);
  sprintf(buffer, "%7.2lfMB", mbs);
  return buffer;
}
#endif // PRODUCT

size_t G1CollectorPolicy::max_regions(int purpose) {
  switch (purpose) {
    case GCAllocForSurvived:
      return _max_survivor_regions;
    case GCAllocForTenured:
      return REGIONS_UNLIMITED;
    default:
      ShouldNotReachHere();
      return REGIONS_UNLIMITED;
  };
}

void G1CollectorPolicy::update_max_gc_locker_expansion() {
  size_t 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 = (size_t) ceil(expansion_region_num_d);
  } else {
    assert(expansion_region_num == 0, "sanity");
  }
  _young_list_max_length = _young_list_target_length + expansion_region_num;
  assert(_young_list_target_length <= _young_list_max_length, "post-condition");
}

// Calculates survivor space parameters.
void G1CollectorPolicy::update_survivors_policy() {
  double max_survivor_regions_d =
                 (double) _young_list_target_length / (double) SurvivorRatio;
  // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
  // smaller than 1.0) we'll get 1.
  _max_survivor_regions = (size_t) ceil(max_survivor_regions_d);

  _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
        HeapRegion::GrainWords * _max_survivor_regions);
}

#ifndef PRODUCT
class HRSortIndexIsOKClosure: public HeapRegionClosure {
  CollectionSetChooser* _chooser;
public:
  HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
    _chooser(chooser) {}

  bool doHeapRegion(HeapRegion* r) {
    if (!r->continuesHumongous()) {
      assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
    }
    return false;
  }
};

bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  HRSortIndexIsOKClosure cl(_collectionSetChooser);
  _g1->heap_region_iterate(&cl);
  return true;
}
#endif

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();

      // 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"));
    }
  }
}

void
G1CollectorPolicy_BestRegionsFirst::
record_collection_pause_start(double start_time_sec, size_t start_used) {
  G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
}

class KnownGarbageClosure: public HeapRegionClosure {
  CollectionSetChooser* _hrSorted;

public:
  KnownGarbageClosure(CollectionSetChooser* hrSorted) :
    _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 don't include humongous regions in collection
      // sets because we collect them immediately at the end of a marking
      // cycle.  We also don't include young regions because we *must*
      // include them in the next collection pause.
      if (!r->isHumongous() && !r->is_young()) {
        _hrSorted->addMarkedHeapRegion(r);
      }
    }
    return false;
  }
};

class ParKnownGarbageHRClosure: public HeapRegionClosure {
  CollectionSetChooser* _hrSorted;
  jint _marked_regions_added;
  jint _chunk_size;
  jint _cur_chunk_idx;
  jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  int _worker;
  int _invokes;

  void get_new_chunk() {
    _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
    _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  }
  void add_region(HeapRegion* r) {
    if (_cur_chunk_idx == _cur_chunk_end) {
      get_new_chunk();
    }
    assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
    _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
    _marked_regions_added++;
    _cur_chunk_idx++;
  }

public:
  ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
                           jint chunk_size,
                           int worker) :
    _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
    _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
    _invokes(0)
  {}

  bool doHeapRegion(HeapRegion* r) {
    // We only include humongous regions in collection
    // sets when concurrent mark shows that their contained object is
    // unreachable.
    _invokes++;

    // Do we have any marking information for this region?
    if (r->is_marked()) {
      // We don't include humongous regions in collection
      // sets because we collect them immediately at the end of a marking
      // cycle.
      // We also do not include young regions in collection sets
      if (!r->isHumongous() && !r->is_young()) {
        add_region(r);
      }
    }
    return false;
  }
  jint marked_regions_added() { return _marked_regions_added; }
  int invokes() { return _invokes; }
};

class ParKnownGarbageTask: public AbstractGangTask {
  CollectionSetChooser* _hrSorted;
  jint _chunk_size;
  G1CollectedHeap* _g1;
public:
  ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
    AbstractGangTask("ParKnownGarbageTask"),
    _hrSorted(hrSorted), _chunk_size(chunk_size),
    _g1(G1CollectedHeap::heap())
  {}

  void work(int i) {
    ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
    // Back to zero for the claim value.
    _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
                                         HeapRegion::InitialClaimValue);
    jint regions_added = parKnownGarbageCl.marked_regions_added();
    _hrSorted->incNumMarkedHeapRegions(regions_added);
    if (G1PrintParCleanupStats) {
      gclog_or_tty->print_cr("     Thread %d called %d times, added %d regions to list.",
                 i, parKnownGarbageCl.invokes(), regions_added);
    }
  }
};

void
G1CollectorPolicy_BestRegionsFirst::
record_concurrent_mark_cleanup_end(size_t freed_bytes,
                                   size_t max_live_bytes) {
  double start;
  if (G1PrintParCleanupStats) start = os::elapsedTime();
  record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);

  _collectionSetChooser->clearMarkedHeapRegions();
  double clear_marked_end;
  if (G1PrintParCleanupStats) {
    clear_marked_end = os::elapsedTime();
    gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
                  (clear_marked_end - start)*1000.0);
  }
  if (G1CollectedHeap::use_parallel_gc_threads()) {
    const size_t OverpartitionFactor = 4;
    const size_t MinWorkUnit = 8;
    const size_t WorkUnit =
      MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
           MinWorkUnit);
    _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_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);
  }
  double known_garbage_end;
  if (G1PrintParCleanupStats) {
    known_garbage_end = os::elapsedTime();
    gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
                  (known_garbage_end - clear_marked_end)*1000.0);
  }
  _collectionSetChooser->sortMarkedHeapRegions();
  double sort_end;
  if (G1PrintParCleanupStats) {
    sort_end = os::elapsedTime();
    gclog_or_tty->print_cr("  sorting: %8.3f ms.",
                  (sort_end - known_garbage_end)*1000.0);
  }

  record_concurrent_mark_cleanup_end_work2();
  double work2_end;
  if (G1PrintParCleanupStats) {
    work2_end = os::elapsedTime();
    gclog_or_tty->print_cr("  work2: %8.3f ms.",
                  (work2_end - sort_end)*1000.0);
  }
}

// Add the heap region at the head of the non-incremental collection set
void G1CollectorPolicy::
add_to_collection_set(HeapRegion* hr) {
  assert(_inc_cset_build_state == Active, "Precondition");
  assert(!hr->is_young(), "non-incremental add of young region");

  if (_g1->mark_in_progress())
    _g1->concurrent_mark()->registerCSetRegion(hr);

  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_size++;
  _collection_set_bytes_used_before += hr->used();
  _g1->register_region_with_in_cset_fast_test(hr);
}

// 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_size = 0;
  _inc_cset_bytes_used_before = 0;

  _inc_cset_young_index = 0;

  _inc_cset_max_finger = 0;
  _inc_cset_recorded_young_bytes = 0;
  _inc_cset_recorded_rs_lengths = 0;
  _inc_cset_predicted_elapsed_time_ms = 0;
  _inc_cset_predicted_bytes_to_copy = 0;
  _inc_cset_build_state = Active;
}

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, true);
  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);

#if PREDICTIONS_VERBOSE
  size_t bytes_to_copy = predict_bytes_to_copy(hr);
  _inc_cset_predicted_bytes_to_copy += bytes_to_copy;

  // Record the number of bytes used in this region
  _inc_cset_recorded_young_bytes += 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_predicted_bytes_to_copy(bytes_to_copy);
#endif // PREDICTIONS_VERBOSE
}

void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
  // This routine is currently only called as part of the updating of
  // existing policy information for regions in the incremental cset that
  // is performed by the concurrent refine thread(s) as part of young list
  // RSet sampling. Therefore we should not be at a safepoint.

  assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
  assert(hr->is_young(), "it should be");

  size_t used_bytes = hr->used();
  size_t old_rs_length = hr->recorded_rs_length();
  double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();

  // Subtract the old recorded/predicted policy information for
  // the given heap region from the collection set info.
  _inc_cset_recorded_rs_lengths -= old_rs_length;
  _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;

  _inc_cset_bytes_used_before -= used_bytes;

  // Clear the values cached in the heap region
  hr->set_recorded_rs_length(0);
  hr->set_predicted_elapsed_time_ms(0);

#if PREDICTIONS_VERBOSE
  size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
  _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;

  // Subtract the number of bytes used in this region
  _inc_cset_recorded_young_bytes -= used_bytes;

  // Clear the values cached in the heap region
  hr->set_predicted_bytes_to_copy(0);
#endif // PREDICTIONS_VERBOSE
}

void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
  // Update the collection set information that is dependent on the new RS length
  assert(hr->is_young(), "Precondition");

  remove_from_incremental_cset_info(hr);
  add_to_incremental_cset_info(hr, new_rs_length);
}

void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
  assert( hr->is_young(), "invariant");
  assert( hr->young_index_in_cset() == -1, "invariant" );
  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");

  _inc_cset_size++;
  _g1->register_region_with_in_cset_fast_test(hr);

  hr->set_young_index_in_cset((int) _inc_cset_young_index);
  ++_inc_cset_young_index;
}

// 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_survivor(), "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("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
                 "age: %4d, y: %d, surv: %d",
                        csr->bottom(), csr->end(),
                        csr->top(),
                        csr->prev_top_at_mark_start(),
                        csr->next_top_at_mark_start(),
                        csr->top_at_conc_mark_count(),
                        csr->age_in_surv_rate_group_cond(),
                        csr->is_young(),
                        csr->is_survivor());
    csr = next;
  }
}
#endif // !PRODUCT

void
G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
                                                  double target_pause_time_ms) {
  // Set this here - in case we're not doing young collections.
  double non_young_start_time_sec = os::elapsedTime();

  YoungList* young_list = _g1->young_list();

  start_recording_regions();

  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 = target_pause_time_ms - base_time_ms;

  ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
                "start choosing CSet",
                ergo_format_ms("predicted base time")
                ergo_format_ms("remaining time")
                ergo_format_ms("target pause time"),
                base_time_ms, time_remaining_ms, target_pause_time_ms);

  // the 10% and 50% values are arbitrary...
  double threshold = 0.10 * target_pause_time_ms;
  if (time_remaining_ms < threshold) {
    double prev_time_remaining_ms = time_remaining_ms;
    time_remaining_ms = 0.50 * target_pause_time_ms;
    _within_target = false;
    ergo_verbose3(ErgoCSetConstruction,
                  "adjust remaining time",
                  ergo_format_reason("remaining time lower than threshold")
                  ergo_format_ms("remaining time")
                  ergo_format_ms("threshold")
                  ergo_format_ms("adjusted remaining time"),
                  prev_time_remaining_ms, threshold, time_remaining_ms);
  } else {
    _within_target = true;
  }

  size_t expansion_bytes = _g1->expansion_regions() * HeapRegion::GrainBytes;

  HeapRegion* hr;
  double young_start_time_sec = os::elapsedTime();

  _collection_set_bytes_used_before = 0;
  _collection_set_size = 0;
  _young_cset_length  = 0;
  _last_young_gc_full = full_young_gcs() ? true : false;

  if (_last_young_gc_full) {
    ++_full_young_pause_num;
  } else {
    ++_partial_young_pause_num;
  }

  // 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].

  size_t survivor_region_num = young_list->survivor_length();
  size_t eden_region_num = young_list->length() - survivor_region_num;
  size_t old_region_num = 0;
  hr = young_list->first_survivor_region();
  while (hr != NULL) {
    assert(hr->is_survivor(), "badly formed young list");
    hr->set_young();
    hr = hr->get_next_young_region();
  }

  // Clear the fields that point to the survivor list - they are all young now.
  young_list->clear_survivors();

  if (_g1->mark_in_progress())
    _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);

  _young_cset_length = _inc_cset_young_index;
  _collection_set = _inc_cset_head;
  _collection_set_size = _inc_cset_size;
  _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
  time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
  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_num, survivor_region_num,
                _inc_cset_predicted_elapsed_time_ms);

  // The number of recorded young regions is the incremental
  // collection set's current size
  set_recorded_young_regions(_inc_cset_size);
  set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
  set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
#if PREDICTIONS_VERBOSE
  set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
#endif // PREDICTIONS_VERBOSE

  assert(_inc_cset_size == young_list->length(), "Invariant");

  double young_end_time_sec = os::elapsedTime();
  _recorded_young_cset_choice_time_ms =
    (young_end_time_sec - young_start_time_sec) * 1000.0;

  // We are doing young collections so reset this.
  non_young_start_time_sec = young_end_time_sec;

  if (!full_young_gcs()) {
    bool should_continue = true;
    NumberSeq seq;
    double avg_prediction = 100000000000000000.0; // something very large

    size_t prev_collection_set_size = _collection_set_size;
    double prev_predicted_pause_time_ms = predicted_pause_time_ms;
    do {
      hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
                                                      avg_prediction);
      if (hr != NULL) {
        double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
        time_remaining_ms -= predicted_time_ms;
        predicted_pause_time_ms += predicted_time_ms;
        add_to_collection_set(hr);
        record_non_young_cset_region(hr);
        seq.add(predicted_time_ms);
        avg_prediction = seq.avg() + seq.sd();
      }

      should_continue = true;
      if (hr == NULL) {
        // No need for an ergo verbose message here,
        // getNextMarkRegion() does this when it returns NULL.
        should_continue = false;
      } else {
        if (adaptive_young_list_length()) {
          if (time_remaining_ms < 0.0) {
            ergo_verbose1(ErgoCSetConstruction,
                          "stop adding old regions to CSet",
                          ergo_format_reason("remaining time is lower than 0")
                          ergo_format_ms("remaining time"),
                          time_remaining_ms);
            should_continue = false;
          }
        } else {
          if (_collection_set_size >= _young_list_fixed_length) {
            ergo_verbose2(ErgoCSetConstruction,
                          "stop adding old regions to CSet",
                          ergo_format_reason("CSet length reached target")
                          ergo_format_region("CSet")
                          ergo_format_region("young target"),
                          _collection_set_size, _young_list_fixed_length);
            should_continue = false;
          }
        }
      }
    } while (should_continue);

    if (!adaptive_young_list_length() &&
        _collection_set_size < _young_list_fixed_length) {
      ergo_verbose2(ErgoCSetConstruction,
                    "request partially-young GCs end",
                    ergo_format_reason("CSet length lower than target")
                    ergo_format_region("CSet")
                    ergo_format_region("young target"),
                    _collection_set_size, _young_list_fixed_length);
      _should_revert_to_full_young_gcs  = true;
    }

    old_region_num = _collection_set_size - prev_collection_set_size;

    ergo_verbose2(ErgoCSetConstruction | ErgoHigh,
                  "add old regions to CSet",
                  ergo_format_region("old")
                  ergo_format_ms("predicted old region time"),
                  old_region_num,
                  predicted_pause_time_ms - prev_predicted_pause_time_ms);
  }

  stop_incremental_cset_building();

  count_CS_bytes_used();

  end_recording_regions();

  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_num, survivor_region_num, old_region_num,
                predicted_pause_time_ms, target_pause_time_ms);

  double non_young_end_time_sec = os::elapsedTime();
  _recorded_non_young_cset_choice_time_ms =
    (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
}

void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  G1CollectorPolicy::record_full_collection_end();
  _collectionSetChooser->updateAfterFullCollection();
}

void G1CollectorPolicy_BestRegionsFirst::
record_collection_pause_end() {
  G1CollectorPolicy::record_collection_pause_end();
  assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
}