Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2001-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 #include "incls/_precompiled.incl"

 #include "incls/_g1CollectorPolicy.cpp.incl"

 #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

 };

 static double cost_per_scan_only_region_ms_defaults[] = {

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

 };

 // 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>

 G1CollectorPolicy::G1CollectorPolicy() :

   _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),

   _n_pauses(0),

   _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _recent_evac_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()),

   _all_mod_union_times_ms(new NumberSeq()),

   _summary(new Summary()),

   _abandoned_summary(new AbandonedSummary()),

   _cur_clear_ct_time_ms(0.0),

   _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_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _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)),

   _cost_per_scan_only_region_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)),

   _cost_per_scan_only_region_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>

   _in_young_gc_mode(false),

   _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)),

   _target_pause_time_ms(-1.0),

    _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),

   _conc_mark_initiated(false),

   _should_initiate_conc_mark(false),

   _should_revert_to_full_young_gcs(false),

   _last_full_young_gc(false),

   _prev_collection_pause_used_at_end_bytes(0),

   _collection_set(NULL),

 #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)

 {

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

   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;

   _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_scan_only_times_ms = new double[_parallel_gc_threads];

   _par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];

   _par_last_update_rs_start_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_start_times_ms = new double[_parallel_gc_threads];

   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];

   _par_last_scan_new_refs_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];

   // 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]);

   _cost_per_scan_only_region_ms_seq->add(

                                  cost_per_scan_only_region_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>

   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;

   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;

   guarantee(max_gc_time < time_slice,

             "Max GC time should not be greater than the time slice");

   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);

   _sigma = (double) G1ConfidencePercent / 100.0;

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

   _concurrent_mark_init_times_ms->add(0.05);

   _concurrent_mark_remark_times_ms->add(0.05);

   _concurrent_mark_cleanup_times_ms->add(0.20);

   _tenuring_threshold = MaxTenuringThreshold;

   if (G1UseSurvivorSpaces) {

     // if G1FixedSurvivorSpaceSize is 0 which means the size is not

     // fixed, then _max_survivor_regions will be calculated at

     // calculate_young_list_target_config during initialization

     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;

   } else {

     _max_survivor_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();

 }

 void G1CollectorPolicy::init() {

   // Set aside an initial future to_space.

   _g1 = G1CollectedHeap::heap();

   size_t regions = Universe::heap()->capacity() / HeapRegion::GrainBytes;

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

   if (G1SteadyStateUsed < 50) {

     vm_exit_during_initialization("G1SteadyStateUsed must be at least 50%.");

   }

   initialize_gc_policy_counters();

   if (G1Gen) {

     _in_young_gc_mode = true;

     if (G1YoungGenSize == 0) {

       set_adaptive_young_list_length(true);

       _young_list_fixed_length = 0;

     } else {

       set_adaptive_young_list_length(false);

       _young_list_fixed_length = (G1YoungGenSize / HeapRegion::GrainBytes);

     }

      _free_regions_at_end_of_collection = _g1->free_regions();

      _scan_only_regions_at_end_of_collection = 0;

      calculate_young_list_min_length();

      guarantee( _young_list_min_length == 0, "invariant, not enough info" );

      calculate_young_list_target_config();

    } else {

      _young_list_fixed_length = 0;

     _in_young_gc_mode = false;

   }

 }

 // Create the jstat counters for the policy.

 void G1CollectorPolicy::initialize_gc_policy_counters()

 {

   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);

 }

 void G1CollectorPolicy::calculate_young_list_min_length() {

   _young_list_min_length = 0;

   if (!adaptive_young_list_length())

     return;

   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();

     int min_regions = (int) ceil(alloc_rate_ms * when_ms);

     int current_region_num = (int) _g1->young_list_length();

     _young_list_min_length = min_regions + current_region_num;

   }

 }

 void G1CollectorPolicy::calculate_young_list_target_config() {

   if (adaptive_young_list_length()) {

     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);

     calculate_young_list_target_config(rs_lengths);

   } else {

     if (full_young_gcs())

       _young_list_target_length = _young_list_fixed_length;

     else

       _young_list_target_length = _young_list_fixed_length / 2;

     _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);

     size_t so_length = calculate_optimal_so_length(_young_list_target_length);

     guarantee( so_length < _young_list_target_length, "invariant" );

     _young_list_so_prefix_length = so_length;

   }

   calculate_survivors_policy();

 }

 // This method calculate the optimal scan-only set for a fixed young

 // gen size. I couldn't work out how to reuse the more elaborate one,

 // i.e. calculate_young_list_target_config(rs_length), as the loops are

 // fundamentally different (the other one finds a config for different

 // S-O lengths, whereas here we need to do the opposite).

 size_t G1CollectorPolicy::calculate_optimal_so_length(

                                                     size_t young_list_length) {

   if (!G1UseScanOnlyPrefix)

     return 0;

   if (_all_pause_times_ms->num() < 3) {

     // we won't use a scan-only set at the beginning to allow the rest

     // of the predictors to warm up

     return 0;

   }

   if (_cost_per_scan_only_region_ms_seq->num() < 3) {

     // then, we'll only set the S-O set to 1 for a little bit of time,

     // to get enough information on the scanning cost

     return 1;

   }

   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);

   size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);

   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();

   size_t scanned_cards;

   if (full_young_gcs())

     scanned_cards = predict_young_card_num(adj_rs_lengths);

   else

     scanned_cards = predict_non_young_card_num(adj_rs_lengths);

   double base_time_ms = predict_base_elapsed_time_ms(pending_cards,

                                                      scanned_cards);

   size_t so_length = 0;

   double max_gc_eff = 0.0;

   for (size_t i = 0; i < young_list_length; ++i) {

     double gc_eff = 0.0;

     double pause_time_ms = 0.0;

     predict_gc_eff(young_list_length, i, base_time_ms,

                    &gc_eff, &pause_time_ms);

     if (gc_eff > max_gc_eff) {

       max_gc_eff = gc_eff;

       so_length = i;

     }

   }

   // set it to 95% of the optimal to make sure we sample the "area"

   // around the optimal length to get up-to-date survival rate data

   return so_length * 950 / 1000;

 }

 // This is a really cool piece of code! It finds the best

 // target configuration (young length / scan-only prefix length) so

 // that GC efficiency is maximized and that we also meet a pause

 // time. It's a triple nested loop. These loops are explained below

 // from the inside-out :-)

 //

 // (a) The innermost loop will try to find the optimal young length

 // for a fixed S-O length. It uses a binary search to speed up the

 // process. We assume that, for a fixed S-O length, as we add more

 // young regions to the CSet, the GC efficiency will only go up (I'll

 // skip the proof). So, using a binary search to optimize this process

 // makes perfect sense.

 //

 // (b) The middle loop will fix the S-O length before calling the

 // innermost one. It will vary it between two parameters, increasing

 // it by a given increment.

 //

 // (c) The outermost loop will call the middle loop three times.

 //   (1) The first time it will explore all possible S-O length values

 //   from 0 to as large as it can get, using a coarse increment (to

 //   quickly "home in" to where the optimal seems to be).

 //   (2) The second time it will explore the values around the optimal

 //   that was found by the first iteration using a fine increment.

 //   (3) Once the optimal config has been determined by the second

 //   iteration, we'll redo the calculation, but setting the S-O length

 //   to 95% of the optimal to make sure we sample the "area"

 //   around the optimal length to get up-to-date survival rate data

 //

 // Termination conditions for the iterations are several: the pause

 // time is over the limit, we do not have enough to-space, etc.

 void G1CollectorPolicy::calculate_young_list_target_config(size_t rs_lengths) {

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

   double start_time_sec = os::elapsedTime();

   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1MinReservePercent);

   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);

   size_t reserve_regions =

     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);

   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {

     // we are in fully-young mode and there are free regions in the heap

     double survivor_regions_evac_time =

         predict_survivor_regions_evac_time();

     size_t min_so_length = 0;

     size_t max_so_length = 0;

     if (G1UseScanOnlyPrefix) {

       if (_all_pause_times_ms->num() < 3) {

         // we won't use a scan-only set at the beginning to allow the rest

         // of the predictors to warm up

         min_so_length = 0;

         max_so_length = 0;

       } else if (_cost_per_scan_only_region_ms_seq->num() < 3) {

         // then, we'll only set the S-O set to 1 for a little bit of time,

         // to get enough information on the scanning cost

         min_so_length = 1;

         max_so_length = 1;

       } else if (_in_marking_window || _last_full_young_gc) {

         // no S-O prefix during a marking phase either, as at the end

         // of the marking phase we'll have to use a very small young

         // length target to fill up the rest of the CSet with

         // non-young regions and, if we have lots of scan-only regions

         // left-over, we will not be able to add any more non-young

         // regions.

         min_so_length = 0;

         max_so_length = 0;

       } else {

         // this is the common case; we'll never reach the maximum, we

         // one of the end conditions will fire well before that

         // (hopefully!)

         min_so_length = 0;

         max_so_length = _free_regions_at_end_of_collection - 1;

       }

     } else {

       // no S-O prefix, as the switch is not set, but we still need to

       // do one iteration to calculate the best young target that

       // meets the pause time; this way we reuse the same code instead

       // of replicating it

       min_so_length = 0;

       max_so_length = 0;

     }

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

     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;

     if (full_young_gcs())

       scanned_cards = predict_young_card_num(adj_rs_lengths);

     else

       scanned_cards = predict_non_young_card_num(adj_rs_lengths);

     // calculate this once, so that we don't have to recalculate it in

     // the innermost loop

     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)

                           + survivor_regions_evac_time;

     // the result

     size_t final_young_length = 0;

     size_t final_so_length = 0;

     double final_gc_eff = 0.0;

     // we'll also keep track of how many times we go into the inner loop

     // this is for profiling reasons

     size_t calculations = 0;

     // this determines which of the three iterations the outer loop is in

     typedef enum {

       pass_type_coarse,

       pass_type_fine,

       pass_type_final

     } pass_type_t;

     // range of the outer loop's iteration

     size_t from_so_length   = min_so_length;

     size_t to_so_length     = max_so_length;

     guarantee( from_so_length <= to_so_length, "invariant" );

     // this will keep the S-O length that's found by the second

     // iteration of the outer loop; we'll keep it just in case the third

     // iteration fails to find something

     size_t fine_so_length   = 0;

     // the increment step for the coarse (first) iteration

     size_t so_coarse_increments = 5;

     // the common case, we'll start with the coarse iteration

     pass_type_t pass = pass_type_coarse;

     size_t so_length_incr = so_coarse_increments;

     if (from_so_length == to_so_length) {

       // not point in doing the coarse iteration, we'll go directly into

       // the fine one (we essentially trying to find the optimal young

       // length for a fixed S-O length).

       so_length_incr = 1;

       pass = pass_type_final;

     } else if (to_so_length - from_so_length < 3 * so_coarse_increments) {

       // again, the range is too short so no point in foind the coarse

       // iteration either

       so_length_incr = 1;

       pass = pass_type_fine;

     }

     bool done = false;

     // this is the outermost loop

     while (!done) {

 #ifdef TRACE_CALC_YOUNG_CONFIG

       // leave this in for debugging, just in case

       gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT

                              ", incr " SIZE_FORMAT ", pass %s",

                              from_so_length, to_so_length, so_length_incr,

                              (pass == pass_type_coarse) ? "coarse" :

                              (pass == pass_type_fine) ? "fine" : "final");

 #endif // TRACE_CALC_YOUNG_CONFIG

       size_t so_length = from_so_length;

       size_t init_free_regions =

         MAX2((size_t)0,

              _free_regions_at_end_of_collection +

              _scan_only_regions_at_end_of_collection - reserve_regions);

       // this determines whether a configuration was found

       bool gc_eff_set = false;

       // this is the middle loop

       while (so_length <= to_so_length) {

         // base time, which excludes region-related time; again we

         // calculate it once to avoid recalculating it in the

         // innermost loop

         double base_time_with_so_ms =

                            base_time_ms + predict_scan_only_time_ms(so_length);

         // it's already over the pause target, go around

         if (base_time_with_so_ms > target_pause_time_ms)

           break;

         size_t starting_young_length = so_length+1;

         // we make sure that the short young length that makes sense

         // (one more than the S-O length) is feasible

         size_t min_young_length = starting_young_length;

         double min_gc_eff;

         bool min_ok;

         ++calculations;

         min_ok = predict_gc_eff(min_young_length, so_length,

                                 base_time_with_so_ms,

                                 init_free_regions, target_pause_time_ms,

                                 &min_gc_eff);

         if (min_ok) {

           // the shortest young length is indeed feasible; we'll know

           // set up the max young length and we'll do a binary search

           // between min_young_length and max_young_length

           size_t max_young_length = _free_regions_at_end_of_collection - 1;

           double max_gc_eff = 0.0;

           bool max_ok = false;

           // the innermost loop! (finally!)

           while (max_young_length > min_young_length) {

             // we'll make sure that min_young_length is always at a

             // feasible config

             guarantee( min_ok, "invariant" );

             ++calculations;

             max_ok = predict_gc_eff(max_young_length, so_length,

                                     base_time_with_so_ms,

                                     init_free_regions, target_pause_time_ms,

                                     &max_gc_eff);

             size_t diff = (max_young_length - min_young_length) / 2;

             if (max_ok) {

               min_young_length = max_young_length;

               min_gc_eff = max_gc_eff;

               min_ok = true;

             }

             max_young_length = min_young_length + diff;

           }

           // the innermost loop found a config

           guarantee( min_ok, "invariant" );

           if (min_gc_eff > final_gc_eff) {

             // it's the best config so far, so we'll keep it

             final_gc_eff = min_gc_eff;

             final_young_length = min_young_length;

             final_so_length = so_length;

             gc_eff_set = true;

           }

         }

         // incremental the fixed S-O length and go around

         so_length += so_length_incr;

       }

       // this is the end of the outermost loop and we need to decide

       // what to do during the next iteration

       if (pass == pass_type_coarse) {

         // we just did the coarse pass (first iteration)

         if (!gc_eff_set)

           // we didn't find a feasible config so we'll just bail out; of

           // course, it might be the case that we missed it; but I'd say

           // it's a bit unlikely

           done = true;

         else {

           // We did find a feasible config with optimal GC eff during

           // the first pass. So the second pass we'll only consider the

           // S-O lengths around that config with a fine increment.

           guarantee( so_length_incr == so_coarse_increments, "invariant" );

           guarantee( final_so_length >= min_so_length, "invariant" );

 #ifdef TRACE_CALC_YOUNG_CONFIG

           // leave this in for debugging, just in case

           gclog_or_tty->print_cr("  coarse pass: SO length " SIZE_FORMAT,

                                  final_so_length);

 #endif // TRACE_CALC_YOUNG_CONFIG

           from_so_length =

             (final_so_length - min_so_length > so_coarse_increments) ?

             final_so_length - so_coarse_increments + 1 : min_so_length;

           to_so_length =

             (max_so_length - final_so_length > so_coarse_increments) ?

             final_so_length + so_coarse_increments - 1 : max_so_length;

           pass = pass_type_fine;

           so_length_incr = 1;

         }

       } else if (pass == pass_type_fine) {

         // we just finished the second pass

         if (!gc_eff_set) {

           // we didn't find a feasible config (yes, it's possible;

           // notice that, sometimes, we go directly into the fine

           // iteration and skip the coarse one) so we bail out

           done = true;

         } else {

           // We did find a feasible config with optimal GC eff

           guarantee( so_length_incr == 1, "invariant" );

           if (final_so_length == 0) {

             // The config is of an empty S-O set, so we'll just bail out

             done = true;

           } else {

             // we'll go around once more, setting the S-O length to 95%

             // of the optimal

             size_t new_so_length = 950 * final_so_length / 1000;

 #ifdef TRACE_CALC_YOUNG_CONFIG

             // leave this in for debugging, just in case

             gclog_or_tty->print_cr("  fine pass: SO length " SIZE_FORMAT

                                    ", setting it to " SIZE_FORMAT,

                                     final_so_length, new_so_length);

 #endif // TRACE_CALC_YOUNG_CONFIG

             from_so_length = new_so_length;

             to_so_length = new_so_length;

             fine_so_length = final_so_length;

             pass = pass_type_final;

           }

         }

       } else if (pass == pass_type_final) {

         // we just finished the final (third) pass

         if (!gc_eff_set)

           // we didn't find a feasible config, so we'll just use the one

           // we found during the second pass, which we saved

           final_so_length = fine_so_length;

         // and we're done!

         done = true;

       } else {

         guarantee( false, "should never reach here" );

       }

       // we now go around the outermost loop

     }

     // we should have at least one region in the target young length

     _young_list_target_length =

         MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);

     if (final_so_length >= final_young_length)

       // and we need to ensure that the S-O length is not greater than

       // the target young length (this is being a bit careful)

       final_so_length = 0;

     _young_list_so_prefix_length = final_so_length;

     guarantee( !_in_marking_window || !_last_full_young_gc ||

                _young_list_so_prefix_length == 0, "invariant" );

     // let's keep an eye of how long we spend on this calculation

     // right now, I assume that we'll print it when we need it; we

     // should really adde it to the breakdown of a pause

     double end_time_sec = os::elapsedTime();

     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;

 #ifdef TRACE_CALC_YOUNG_CONFIG

     // leave this in for debugging, just in case

     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT

                            ", SO = " SIZE_FORMAT ", "

                            "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "

                            SIZE_FORMAT SIZE_FORMAT,

                            target_pause_time_ms,

                            _young_list_target_length - _young_list_so_prefix_length,

                            _young_list_so_prefix_length,

                            elapsed_time_ms,

                            calculations,

                            full_young_gcs() ? "full" : "partial",

                            should_initiate_conc_mark() ? " i-m" : "",

                            _in_marking_window,

                            _in_marking_window_im);

 #endif // TRACE_CALC_YOUNG_CONFIG

     if (_young_list_target_length < _young_list_min_length) {

       // bummer; this means that, if we do a pause when the optimal

       // config dictates, we'll violate the pause spacing target (the

       // min length was calculate based on the application's current

       // alloc rate);

       // so, we have to bite the bullet, and allocate the minimum

       // number. We'll violate our target, but we just can't meet it.

       size_t so_length = 0;

       // a note further up explains why we do not want an S-O length

       // during marking

       if (!_in_marking_window && !_last_full_young_gc)

         // but we can still try to see whether we can find an optimal

         // S-O length

         so_length = calculate_optimal_so_length(_young_list_min_length);

 #ifdef TRACE_CALC_YOUNG_CONFIG

       // leave this in for debugging, just in case

       gclog_or_tty->print_cr("adjusted target length from "

                              SIZE_FORMAT " to " SIZE_FORMAT

                              ", SO " SIZE_FORMAT,

                              _young_list_target_length, _young_list_min_length,

                              so_length);

 #endif // TRACE_CALC_YOUNG_CONFIG

       _young_list_target_length =

         MAX2(_young_list_min_length, (size_t)1);

       _young_list_so_prefix_length = so_length;

     }

   } else {

     // we are in a partially-young mode or we've run out of regions (due

     // to evacuation failure)

 #ifdef TRACE_CALC_YOUNG_CONFIG

     // leave this in for debugging, just in case

     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT

                            ", SO " SIZE_FORMAT,

                            _young_list_min_length, 0);

 #endif // TRACE_CALC_YOUNG_CONFIG

     // we'll do the pause as soon as possible and with no S-O prefix

     // (see above for the reasons behind the latter)

     _young_list_target_length =

       MAX2(_young_list_min_length, (size_t) 1);

     _young_list_so_prefix_length = 0;

   }

   _rs_lengths_prediction = rs_lengths;

 }

 // This is used by: calculate_optimal_so_length(length). It returns

 // the GC eff and predicted pause time for a particular config

 void

 G1CollectorPolicy::predict_gc_eff(size_t young_length,

                                   size_t so_length,

                                   double base_time_ms,

                                   double* ret_gc_eff,

                                   double* ret_pause_time_ms) {

   double so_time_ms = predict_scan_only_time_ms(so_length);

   double accum_surv_rate_adj = 0.0;

   if (so_length > 0)

     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));

   double accum_surv_rate =

     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;

   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 - so_length);

   double pause_time_ms =

                 base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;

   size_t reclaimed_bytes =

     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;

   double gc_eff = (double) reclaimed_bytes / pause_time_ms;

   *ret_gc_eff = gc_eff;

   *ret_pause_time_ms = pause_time_ms;

 }

 // This is used by: calculate_young_list_target_config(rs_length). It

 // returns the GC eff of a particular config. It returns false if that

 // config violates any of the end conditions of the search in the

 // calling method, or true upon success. The end conditions were put

 // here since it's called twice and it was best not to replicate them

 // in the caller. Also, passing the parameteres avoids having to

 // recalculate them in the innermost loop.

 bool

 G1CollectorPolicy::predict_gc_eff(size_t young_length,

                                   size_t so_length,

                                   double base_time_with_so_ms,

                                   size_t init_free_regions,

                                   double target_pause_time_ms,

                                   double* ret_gc_eff) {

   *ret_gc_eff = 0.0;

   if (young_length >= init_free_regions)

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

     return false;

   double accum_surv_rate_adj = 0.0;

   if (so_length > 0)

     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));

   double accum_surv_rate =

     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;

   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 - so_length);

   double pause_time_ms =

                    base_time_with_so_ms + copy_time_ms + young_other_time_ms;

   if (pause_time_ms > target_pause_time_ms)

     // end condition 2: over the target pause time

     return false;

   size_t reclaimed_bytes =

     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;

   size_t free_bytes =

                  (init_free_regions - young_length) * HeapRegion::GrainBytes;

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

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

     return false;

   // success!

   double gc_eff = (double) reclaimed_bytes / pause_time_ms;

   *ret_gc_eff = gc_eff;

   return true;

 }

 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::check_prediction_validity() {

   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;

     calculate_young_list_target_config(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;

   checkpoint_conc_overhead();

   _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;

   _should_initiate_conc_mark = false;

   _known_garbage_bytes = 0;

   _known_garbage_ratio = 0.0;

   _in_marking_window = false;

   _in_marking_window_im = false;

   _short_lived_surv_rate_group->record_scan_only_prefix(0);

   _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();

   _scan_only_regions_at_end_of_collection = 0;

   // Reset survivors SurvRateGroup.

   _survivor_surv_rate_group->reset();

   calculate_young_list_min_length();

   calculate_young_list_target_config();

  }

 void G1CollectorPolicy::record_before_bytes(size_t bytes) {

   _bytes_in_to_space_before_gc += bytes;

 }

 void G1CollectorPolicy::record_after_bytes(size_t bytes) {

   _bytes_in_to_space_after_gc += bytes;

 }

 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");

     if (in_young_gc_mode())

       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");

   }

   assert(_g1->used_regions() == _g1->recalculate_used_regions(),

          "sanity");

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

   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_to_space_before_gc = 0;

   _bytes_in_to_space_after_gc = 0;

   _bytes_in_collection_set_before_gc = 0;

 #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_ext_root_scan_times_ms[i] = -666.0;

     _par_last_mark_stack_scan_times_ms[i] = -666.0;

     _par_last_scan_only_times_ms[i] = -666.0;

     _par_last_scan_only_regions_scanned[i] = -666.0;

     _par_last_update_rs_start_times_ms[i] = -666.0;

     _par_last_update_rs_times_ms[i] = -666.0;

     _par_last_update_rs_processed_buffers[i] = -666.0;

     _par_last_scan_rs_start_times_ms[i] = -666.0;

     _par_last_scan_rs_times_ms[i] = -666.0;

     _par_last_scan_new_refs_times_ms[i] = -666.0;

     _par_last_obj_copy_times_ms[i] = -666.0;

     _par_last_termination_times_ms[i] = -666.0;

   }

 #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;

   if (in_young_gc_mode())

     _last_young_gc_full = false;

   // do that for any other surv rate groups

   _short_lived_surv_rate_group->stop_adding_regions();

   size_t short_lived_so_length = _young_list_so_prefix_length;

   _short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);

   tag_scan_only(short_lived_so_length);

   if (G1UseSurvivorSpaces) {

     _survivors_age_table.clear();

   }

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

 }

 void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {

   // done in a way that it can be extended for other surv rate groups too...

   HeapRegion* head = _g1->young_list_first_region();

   bool finished_short_lived = (short_lived_scan_only_length == 0);

   if (finished_short_lived)

     return;

   for (HeapRegion* curr = head;

        curr != NULL;

        curr = curr->get_next_young_region()) {

     SurvRateGroup* surv_rate_group = curr->surv_rate_group();

     int age = curr->age_in_surv_rate_group();

     if (surv_rate_group == _short_lived_surv_rate_group) {

       if ((size_t)age < short_lived_scan_only_length)

         curr->set_scan_only();

       else

         finished_short_lived = true;

     }

     if (finished_short_lived)

       return;

   }

   guarantee( false, "we should never reach here" );

 }

 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_start() {

   _mark_init_start_sec = os::elapsedTime();

   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");

 }

 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double

                                                    mark_init_elapsed_time_ms) {

   _during_marking = true;

   _should_initiate_conc_mark = false;

   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;

 }

 void G1CollectorPolicy::record_concurrent_mark_init_end() {

   double end_time_sec = os::elapsedTime();

   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;

   _concurrent_mark_init_times_ms->add(elapsed_time_ms);

   checkpoint_conc_overhead();

   record_concurrent_mark_init_end_pre(elapsed_time_ms);

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

 }

 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;

   checkpoint_conc_overhead();

   _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++;

   if (G1PolicyVerbose > 0)

     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "

                            " (of " SIZE_FORMAT " MB heap).",

                            max_live_bytes/M, _g1->capacity()/M);

 }

 // The important thing about this is that it includes "os::elapsedTime".

 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {

   checkpoint_conc_overhead();

   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++;

   // We did a marking, so reset the "since_last_mark" variables.

   double considerConcMarkCost = 1.0;

   // If there are available processors, concurrent activity is free...

   if (Threads::number_of_non_daemon_threads() * 2 <

       os::active_processor_count()) {

     considerConcMarkCost = 0.0;

   }

   _n_pauses_at_mark_end = _n_pauses;

   _n_marks_since_last_pause++;

   _conc_mark_initiated = false;

 }

 void

 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {

   if (in_young_gc_mode()) {

     _should_revert_to_full_young_gcs = false;

     _last_full_young_gc = true;

     _in_marking_window = false;

     if (adaptive_young_list_length())

       calculate_young_list_target_config();

   }

 }

 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() {

 }

 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {

   _cur_CH_strong_roots_end_sec = os::elapsedTime();

   _cur_CH_strong_roots_dur_ms =

     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;

 }

 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {

   _cur_G1_strong_roots_end_sec = os::elapsedTime();

   _cur_G1_strong_roots_dur_ms =

     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;

 }

 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,

                                          bool summary) {

   double min = data[0], max = data[0];

   double total = 0.0;

   int j;

   for (j = 0; j < level; ++j)

     gclog_or_tty->print("   ");

   gclog_or_tty->print("[%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;

     gclog_or_tty->print("  %3.1lf", val);

   }

   if (summary) {

     gclog_or_tty->print_cr("");

     double avg = total / (double) ParallelGCThreads;

     gclog_or_tty->print(" ");

     for (j = 0; j < level; ++j)

       gclog_or_tty->print("   ");

     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",

                         avg, min, max);

   }

   gclog_or_tty->print_cr("]");

 }

 void G1CollectorPolicy::print_par_buffers (int level,

                                          const char* str,

                                          double* data,

                                          bool summary) {

   double min = data[0], max = data[0];

   double total = 0.0;

   int j;

   for (j = 0; j < level; ++j)

     gclog_or_tty->print("   ");

   gclog_or_tty->print("[%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;

     gclog_or_tty->print(" %d", (int) val);

   }

   if (summary) {

     gclog_or_tty->print_cr("");

     double avg = total / (double) ParallelGCThreads;

     gclog_or_tty->print(" ");

     for (j = 0; j < level; ++j)

       gclog_or_tty->print("   ");

     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",

                (int)total, (int)avg, (int)min, (int)max);

   }

   gclog_or_tty->print_cr("]");

 }

 void G1CollectorPolicy::print_stats (int level,

                                      const char* str,

                                      double value) {

   for (int j = 0; j < level; ++j)

     gclog_or_tty->print("   ");

   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);

 }

 void G1CollectorPolicy::print_stats (int level,

                                      const char* str,

                                      int value) {

   for (int j = 0; j < level; ++j)

     gclog_or_tty->print("   ");

   gclog_or_tty->print_cr("[%s: %d]", str, value);

 }

 double G1CollectorPolicy::avg_value (double* data) {

   if (ParallelGCThreads > 0) {

     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 (ParallelGCThreads > 0) {

     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 (ParallelGCThreads > 0) {

     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 (ParallelGCThreads > 0) {

     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(bool abandoned) {

   double end_time_sec = os::elapsedTime();

   double elapsed_ms = _last_pause_time_ms;

   bool parallel = ParallelGCThreads > 0;

   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;

   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 = !abandoned && !_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

   checkpoint_conc_overhead();

   if (in_young_gc_mode()) {

     last_pause_included_initial_mark = _should_initiate_conc_mark;

     if (last_pause_included_initial_mark)

       record_concurrent_mark_init_end_pre(0.0);

     size_t min_used_targ =

       (_g1->capacity() / 100) * (G1SteadyStateUsed - G1SteadyStateUsedDelta);

     if (cur_used_bytes > min_used_targ) {

       if (cur_used_bytes <= _prev_collection_pause_used_at_end_bytes) {

       } else if (!_g1->mark_in_progress() && !_last_full_young_gc) {

         _should_initiate_conc_mark = true;

       }

     }

     _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++;

   if (update_stats) {

     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);

     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);

     _recent_evac_times_ms->add(evac_ms);

     _recent_pause_times_ms->add(elapsed_ms);

     _recent_rs_sizes->add(rs_size);

     // 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;

     assert(recent_avg_pause_time_ratio() < 1.00, "All GC?");

   }

   if (G1PolicyVerbose > 1) {

     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);

   }

   PauseSummary* summary;

   if (abandoned) {

     summary = _abandoned_summary;

   } else {

     summary = _summary;

   }

   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 scan_only_time = avg_value(_par_last_scan_only_times_ms);

   double scan_only_regions_scanned =

     sum_of_values(_par_last_scan_only_regions_scanned);

   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_other_time = _cur_collection_par_time_ms -

     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +

      scan_only_time + scan_rs_time + obj_copy_time + termination_time);

   if (update_stats) {

     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_scan_only_time_ms(scan_only_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);

   }

   if (G1PolicyVerbose > 1) {

     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"

                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"

                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"

                            "        Evac:      %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(),

                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),

                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),

                            evac_ms, recent_avg_time_for_evac_ms(),

                            scan_rs_time,

                            recent_avg_time_for_pauses_ms() -

                            recent_avg_time_for_G1_strong_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 (!abandoned) {

     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_only_time +

         scan_rs_time + obj_copy_time;

   }

   if (PrintGCDetails) {

     gclog_or_tty->print_cr("%s%s, %1.8lf secs]",

                            abandoned ? " (abandoned)" : "",

                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",

                            elapsed_ms / 1000.0);

     if (!abandoned) {

       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, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);

         print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);

         print_par_buffers(3, "Processed Buffers",

                           _par_last_update_rs_processed_buffers, true);

         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-Only Scanning", _par_last_scan_only_times_ms);

         print_par_buffers(3, "Scan-Only Regions",

                           _par_last_scan_only_regions_scanned, true);

         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_stats(2, "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-Only Scanning", scan_only_time);

         print_stats(1, "Scan RS", scan_rs_time);

         print_stats(1, "Object Copying", obj_copy_time);

       }

     }

     print_stats(1, "Other", other_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]);

       }

     }

   }

   if (PrintGCDetails)

     gclog_or_tty->print("   [");

   if (PrintGC || PrintGCDetails)

     _g1->print_size_transition(gclog_or_tty,

                                _cur_collection_pause_used_at_start_bytes,

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

   if (PrintGCDetails)

     gclog_or_tty->print_cr("]");

   _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 (_should_initiate_conc_mark) {

     new_in_marking_window = true;

     new_in_marking_window_im = true;

   }

   if (in_young_gc_mode()) {

     if (_last_full_young_gc) {

       set_full_young_gcs(false);

       _last_full_young_gc = false;

     }

     if ( !_last_young_gc_full ) {

       if ( _should_revert_to_full_young_gcs ||

            _known_garbage_ratio < 0.05 ||

            (adaptive_young_list_length() &&

            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {

         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);

     }

     double cost_per_scan_only_region_ms = 0.0;

     if (scan_only_regions_scanned > 0.0) {

       cost_per_scan_only_region_ms =

         scan_only_time / scan_only_regions_scanned;

       if (_in_marking_window_im)

         _cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);

       else

         _cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_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_only_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_in_to_space_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 %d "

                     "PENDING_CARDS %d %d "

                     "CARDS_SCANNED %d %d "

                     "RS_LENGTHS %d %d "

                     "SCAN_ONLY_SCAN %1.6lf %1.6lf "

                     "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_scan_only_regions,

                     _recorded_non_young_regions,

                     _predicted_pending_cards, _pending_cards,

                     _predicted_cards_scanned, cards_scanned,

                     _predicted_rs_lengths, _max_rs_lengths,

                     _predicted_scan_only_scan_time_ms, scan_only_time,

                     _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();

   _scan_only_regions_at_end_of_collection = _g1->young_list_length();

   calculate_young_list_min_length();

   calculate_young_list_target_config();

   // </NEW PREDICTION>

   _target_pause_time_ms = -1.0;

 }

 // <NEW PREDICTION>

 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_scan_only_regions     = 0;

   _recorded_young_regions         = 0;

   _recorded_non_young_regions     = 0;

 #if PREDICTIONS_VERBOSE

   _predicted_rs_lengths           = 0;

   _predicted_cards_scanned        = 0;

   _recorded_marked_bytes          = 0;

   _recorded_young_bytes           = 0;

   _predicted_bytes_to_copy        = 0;

 #endif // PREDICTIONS_VERBOSE

 }

 void

 G1CollectorPolicy::record_cset_region(HeapRegion* hr, bool young) {

   if (young) {

     ++_recorded_young_regions;

   } else {

     ++_recorded_non_young_regions;

   }

 #if PREDICTIONS_VERBOSE

   if (young) {

     _recorded_young_bytes += hr->used();

   } else {

     _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_scan_only_regions(size_t scan_only_length) {

   _recorded_scan_only_regions = scan_only_length;

 }

 void

 G1CollectorPolicy::end_recording_regions() {

 #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_scan_only_scan_time_ms =

     predict_scan_only_time_ms(_recorded_scan_only_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_scan_only_scan_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) {

     if (!in_young_gc_mode()) {

         set_full_young_gcs(true);

       _should_initiate_conc_mark = true;

     } else

       // 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;

   else return _recent_pause_times_ms->avg();

 }

 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {

   if (_recent_CH_strong_roots_times_ms->num() == 0)

     return (double)MaxGCPauseMillis/3.0;

   else return _recent_CH_strong_roots_times_ms->avg();

 }

 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {

   if (_recent_G1_strong_roots_times_ms->num() == 0)

     return (double)MaxGCPauseMillis/3.0;

   else return _recent_G1_strong_roots_times_ms->avg();

 }

 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {

   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;

   else return _recent_evac_times_ms->avg();

 }

 int G1CollectorPolicy::number_of_recent_gcs() {

   assert(_recent_CH_strong_roots_times_ms->num() ==

          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");

   assert(_recent_G1_strong_roots_times_ms->num() ==

          _recent_evac_times_ms->num(), "Sequence out of sync");

   assert(_recent_evac_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 || ParallelGCThreads > 0) ||

              _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 || ParallelGCThreads > 0) ||

            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() {

   if ((int)(recent_avg_pause_time_ratio() * 100.0) > G1GCPercent) {

     // 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->g1_reserved_obj_bytes();

     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);

     if (G1PolicyVerbose > 1) {

       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "

                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"

                  "                   Answer = %d.\n",

                  recent_avg_pause_time_ratio(),

                  byte_size_in_proper_unit(committed_bytes),

                  proper_unit_for_byte_size(committed_bytes),

                  byte_size_in_proper_unit(uncommitted_bytes),

                  proper_unit_for_byte_size(uncommitted_bytes),

                  byte_size_in_proper_unit(expand_bytes_via_pct),

                  proper_unit_for_byte_size(expand_bytes_via_pct),

                  byte_size_in_proper_unit(expand_bytes),

                  proper_unit_for_byte_size(expand_bytes));

     }

     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);

 }

 static void print_indent(int level) {

   for (int j = 0; j < level+1; ++j)

     gclog_or_tty->print("   ");

 }

 void G1CollectorPolicy::print_summary (int level,

                                        const char* str,

                                        NumberSeq* seq) const {

   double sum = seq->sum();

   print_indent(level);

   gclog_or_tty->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);

   print_indent(level + 5);

   gclog_or_tty->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;

   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;

     print_indent(level + 1);

     gclog_or_tty->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;

     print_indent(level + 1);

     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");

   }

   if (other_times_ms->sum() < -0.01) {

     print_indent(level + 1);

     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");

   }

   if (other_times_ms->avg() < -0.01) {

     print_indent(level + 1);

     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");

   }

   if (calc_other_times_ms->sum() < -0.01) {

     should_print = true;

     print_indent(level + 1);

     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");

   }

   if (calc_other_times_ms->avg() < -0.01) {

     should_print = true;

     print_indent(level + 1);

     gclog_or_tty->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 = ParallelGCThreads > 0;

   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-Only Scanning",

                       body_summary->get_scan_only_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_only_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(),

                                         7, 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-Only Scanning",

                       body_summary->get_scan_only_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());

     {

       NumberSeq calc_other_times_ms;

       if (body_summary != NULL) {

         // not abandoned

         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_only_seq(),

             body_summary->get_scan_rs_seq(),

             body_summary->get_obj_copy_seq()

           };

           calc_other_times_ms = NumberSeq(summary->get_total_seq(),

                                           7, other_parts);

         }

       } else {

         // abandoned

         calc_other_times_ms = NumberSeq();

       }

       check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);

     }

   } else {

     print_indent(0);

     gclog_or_tty->print_cr("none");

   }

   gclog_or_tty->print_cr("");

 }

 void

 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {

   bool printed = false;

   if (summary->get_total_seq()->num() > 0) {

     printed = true;

     print_summary(summary);

   }

   if (!printed) {

     print_indent(0);

     gclog_or_tty->print_cr("none");

     gclog_or_tty->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("ABANDONED PAUSES");

     print_abandoned_summary(_abandoned_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

 }

 bool

 G1CollectorPolicy::should_add_next_region_to_young_list() {

   assert(in_young_gc_mode(), "should be in young GC mode");

   bool ret;

   size_t young_list_length = _g1->young_list_length();

   size_t young_list_max_length = _young_list_target_length;

   if (G1FixedEdenSize) {

     young_list_max_length -= _max_survivor_regions;

   }

   if (young_list_length < young_list_max_length) {

     ret = true;

     ++_region_num_young;

   } else {

     ret = false;

     ++_region_num_tenured;

   }

   return ret;

 }

 #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

 void

 G1CollectorPolicy::checkpoint_conc_overhead() {

   double conc_overhead = 0.0;

   if (G1AccountConcurrentOverhead)

     conc_overhead = COTracker::totalPredConcOverhead();

   _mmu_tracker->update_conc_overhead(conc_overhead);

 #if 0

   gclog_or_tty->print(" CO %1.4lf TARGET %1.4lf",

              conc_overhead, _mmu_tracker->max_gc_time());

 #endif

 }

 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;

   };

 }

 // Calculates survivor space parameters.

 void G1CollectorPolicy::calculate_survivors_policy()

 {

   if (!G1UseSurvivorSpaces) {

     return;

   }

   if (G1FixedSurvivorSpaceSize == 0) {

     _max_survivor_regions = _young_list_target_length / SurvivorRatio;

   } else {

     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;

   }

   if (G1FixedTenuringThreshold) {

     _tenuring_threshold = MaxTenuringThreshold;

   } else {

     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(

         HeapRegion::GrainWords * _max_survivor_regions);

   }

 }

 bool

 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t

                                                                word_size) {

   assert(_g1->regions_accounted_for(), "Region leakage!");

   // Initiate a pause when we reach the steady-state "used" target.

   size_t used_hard = (_g1->capacity() / 100) * G1SteadyStateUsed;

   size_t used_soft =

    MAX2((_g1->capacity() / 100) * (G1SteadyStateUsed - G1SteadyStateUsedDelta),

         used_hard/2);

   size_t used = _g1->used();

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

   size_t young_list_length = _g1->young_list_length();

   size_t young_list_max_length = _young_list_target_length;

   if (G1FixedEdenSize) {

     young_list_max_length -= _max_survivor_regions;

   }

   bool reached_target_length = young_list_length >= young_list_max_length;

   if (in_young_gc_mode()) {

     if (reached_target_length) {

       assert( young_list_length > 0 && _g1->young_list_length() > 0,

               "invariant" );

       _target_pause_time_ms = max_pause_time_ms;

       return true;

     }

   } else {

     guarantee( false, "should not reach here" );

   }

   return false;

 }

 #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

 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 NextNonCSElemFinder: public HeapRegionClosure {

   HeapRegion* _res;

 public:

   NextNonCSElemFinder(): _res(NULL) {}

   bool doHeapRegion(HeapRegion* r) {

     if (!r->in_collection_set()) {

       _res = r;

       return true;

     } else {

       return false;

     }

   }

   HeapRegion* res() { return _res; }

 };

 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