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

 /*

  * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.

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

  *

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

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

  * published by the Free Software Foundation.

  *

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

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

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

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

  * accompanied this code).

  *

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

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

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

  *

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

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

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/concurrentG1Refine.hpp"

 #include "gc_implementation/g1/concurrentMark.hpp"

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

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

 #include "gc_implementation/g1/g1CollectorPolicy.hpp"

 #include "gc_implementation/g1/g1ErgoVerbose.hpp"

 #include "gc_implementation/g1/heapRegionRemSet.hpp"

 #include "gc_implementation/shared/gcPolicyCounters.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/java.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "utilities/debug.hpp"

 // Different defaults for different number of GC threads

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

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

 // all the same

 static double rs_length_diff_defaults[] = {

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

 };

 static double cost_per_card_ms_defaults[] = {

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

 };

 // all the same

 static double young_cards_per_entry_ratio_defaults[] = {

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

 };

 static double cost_per_entry_ms_defaults[] = {

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

 };

 static double cost_per_byte_ms_defaults[] = {

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

 };

 // these should be pretty consistent

 static double constant_other_time_ms_defaults[] = {

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

 };

 static double young_other_cost_per_region_ms_defaults[] = {

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

 };

 static double non_young_other_cost_per_region_ms_defaults[] = {

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

 };

 // Help class for avoiding interleaved logging

 class LineBuffer: public StackObj {

 private:

   static const int BUFFER_LEN = 1024;

   static const int INDENT_CHARS = 3;

   char _buffer[BUFFER_LEN];

   int _indent_level;

   int _cur;

   void vappend(const char* format, va_list ap) {

     int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);

     if (res != -1) {

       _cur += res;

     } else {

       DEBUG_ONLY(warning("buffer too small in LineBuffer");)

       _buffer[BUFFER_LEN -1] = 0;

       _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again

     }

   }

 public:

   explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {

     for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {

       _buffer[_cur] = ' ';

     }

   }

 #ifndef PRODUCT

   ~LineBuffer() {

     assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");

   }

 #endif

   void append(const char* format, ...) {

     va_list ap;

     va_start(ap, format);

     vappend(format, ap);

     va_end(ap);

   }

   void append_and_print_cr(const char* format, ...) {

     va_list ap;

     va_start(ap, format);

     vappend(format, ap);

     va_end(ap);

     gclog_or_tty->print_cr("%s", _buffer);

     _cur = _indent_level * INDENT_CHARS;

   }

 };

 G1CollectorPolicy::G1CollectorPolicy() :

   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()

                         ? ParallelGCThreads : 1),

   _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()),

   _summary(new Summary()),

   _cur_clear_ct_time_ms(0.0),

   _mark_closure_time_ms(0.0),

   _cur_ref_proc_time_ms(0.0),

   _cur_ref_enq_time_ms(0.0),

 #ifndef PRODUCT

   _min_clear_cc_time_ms(-1.0),

   _max_clear_cc_time_ms(-1.0),

   _cur_clear_cc_time_ms(0.0),

   _cum_clear_cc_time_ms(0.0),

   _num_cc_clears(0L),

 #endif

   _aux_num(10),

   _all_aux_times_ms(new NumberSeq[_aux_num]),

   _cur_aux_start_times_ms(new double[_aux_num]),

   _cur_aux_times_ms(new double[_aux_num]),

   _cur_aux_times_set(new bool[_aux_num]),

   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),

   _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)),

   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),

   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),

   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),

   _non_young_other_cost_per_region_ms_seq(

                                          new TruncatedSeq(TruncatedSeqLength)),

   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),

   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),

   _pause_time_target_ms((double) MaxGCPauseMillis),

   _gcs_are_young(true),

   _young_pause_num(0),

   _mixed_pause_num(0),

   _during_marking(false),

   _in_marking_window(false),

   _in_marking_window_im(false),

   _known_garbage_ratio(0.0),

   _known_garbage_bytes(0),

   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),

   _recent_prev_end_times_for_all_gcs_sec(

                                 new TruncatedSeq(NumPrevPausesForHeuristics)),

   _recent_avg_pause_time_ratio(0.0),

   _all_full_gc_times_ms(new NumberSeq()),

   _initiate_conc_mark_if_possible(false),

   _during_initial_mark_pause(false),

   _should_revert_to_young_gcs(false),

   _last_young_gc(false),

   _last_gc_was_young(false),

   _eden_bytes_before_gc(0),

   _survivor_bytes_before_gc(0),

   _capacity_before_gc(0),

   _prev_collection_pause_used_at_end_bytes(0),

   _eden_cset_region_length(0),

   _survivor_cset_region_length(0),

   _old_cset_region_length(0),

   _collection_set(NULL),

   _collection_set_bytes_used_before(0),

   // Incremental CSet attributes

   _inc_cset_build_state(Inactive),

   _inc_cset_head(NULL),

   _inc_cset_tail(NULL),

   _inc_cset_bytes_used_before(0),

   _inc_cset_max_finger(NULL),

   _inc_cset_recorded_rs_lengths(0),

   _inc_cset_recorded_rs_lengths_diffs(0),

   _inc_cset_predicted_elapsed_time_ms(0.0),

   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),

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

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

 #endif // _MSC_VER

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

                                                  G1YoungSurvRateNumRegionsSummary)),

   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",

                                               G1YoungSurvRateNumRegionsSummary)),

   // add here any more surv rate groups

   _recorded_survivor_regions(0),

   _recorded_survivor_head(NULL),

   _recorded_survivor_tail(NULL),

   _survivors_age_table(true),

   _gc_overhead_perc(0.0) {

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

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

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

   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());

   HeapRegionRemSet::setup_remset_size();

   G1ErgoVerbose::initialize();

   if (PrintAdaptiveSizePolicy) {

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

     G1ErgoVerbose::set_enabled(true);

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

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

     // changed in the future.

     G1ErgoVerbose::set_level(ErgoHigh);

   } else {

     G1ErgoVerbose::set_enabled(false);

   }

   // Verify PLAB sizes

   const size_t region_size = HeapRegion::GrainWords;

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

     char buffer[128];

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

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

     vm_exit_during_initialization(buffer);

   }

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

   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;

   _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];

   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];

   _par_last_satb_filtering_times_ms = new double[_parallel_gc_threads];

   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];

   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];

   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];

   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];

   _par_last_termination_times_ms = new double[_parallel_gc_threads];

   _par_last_termination_attempts = new double[_parallel_gc_threads];

   _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];

   _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];

   _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];

   // start conservatively

   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;

   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]);

   _young_cards_per_entry_ratio_seq->add(

                                   young_cards_per_entry_ratio_defaults[index]);

   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);

   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);

   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);

   _young_other_cost_per_region_ms_seq->add(

                                young_other_cost_per_region_ms_defaults[index]);

   _non_young_other_cost_per_region_ms_seq->add(

                            non_young_other_cost_per_region_ms_defaults[index]);

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

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

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

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

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

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

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

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

   // explicitly.

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

   // reasonable.

   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {

     if (MaxGCPauseMillis < 1) {

       vm_exit_during_initialization("MaxGCPauseMillis should be "

                                     "greater than 0");

     }

   }

   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

     if (GCPauseIntervalMillis < 1) {

       vm_exit_during_initialization("GCPauseIntervalMillis should be "

                                     "greater than 0");

     }

   }

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

   // the default value.

   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {

     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

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

       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);

     } else {

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

       // pause time target

       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "

                                     "without setting MaxGCPauseMillis");

     }

   }

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

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

   // pause time target is the default value).

   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {

     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);

   }

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

   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {

     char buffer[256];

     jio_snprintf(buffer, 256,

                  "MaxGCPauseMillis (%u) should be less than "

                  "GCPauseIntervalMillis (%u)",

                  MaxGCPauseMillis, GCPauseIntervalMillis);

     vm_exit_during_initialization(buffer);

   }

   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;

   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;

   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);

   _sigma = (double) G1ConfidencePercent / 100.0;

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

   _concurrent_mark_remark_times_ms->add(0.05);

   _concurrent_mark_cleanup_times_ms->add(0.20);

   _tenuring_threshold = MaxTenuringThreshold;

   // _max_survivor_regions will be calculated by

   // update_young_list_target_length() during initialization.

   _max_survivor_regions = 0;

   assert(GCTimeRatio > 0,

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

          "if a user set it to 0");

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

   uintx reserve_perc = G1ReservePercent;

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

   if (reserve_perc > 50) {

     reserve_perc = 50;

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

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

   }

   _reserve_factor = (double) reserve_perc / 100.0;

   // This will be set when the heap is expanded

   // for the first time during initialization.

   _reserve_regions = 0;

   initialize_all();

   _collectionSetChooser = new CollectionSetChooser();

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

 }

 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();

 }

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

   assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");

   assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");

   assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");

   if (FLAG_IS_CMDLINE(NewRatio)) {

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

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

     } else {

       _sizer_kind = SizerNewRatio;

       _adaptive_size = false;

       return;

     }

   }

   if (FLAG_IS_CMDLINE(NewSize)) {

      _min_desired_young_length = MAX2((size_t) 1, NewSize / HeapRegion::GrainBytes);

     if (FLAG_IS_CMDLINE(MaxNewSize)) {

       _max_desired_young_length = MAX2((size_t) 1, MaxNewSize / HeapRegion::GrainBytes);

       _sizer_kind = SizerMaxAndNewSize;

       _adaptive_size = _min_desired_young_length == _max_desired_young_length;

     } else {

       _sizer_kind = SizerNewSizeOnly;

     }

   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {

     _max_desired_young_length = MAX2((size_t) 1, MaxNewSize / HeapRegion::GrainBytes);

     _sizer_kind = SizerMaxNewSizeOnly;

   }

 }

 size_t G1YoungGenSizer::calculate_default_min_length(size_t new_number_of_heap_regions) {

   size_t default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;

   return MAX2((size_t)1, default_value);

 }

 size_t G1YoungGenSizer::calculate_default_max_length(size_t new_number_of_heap_regions) {

   size_t default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;

   return MAX2((size_t)1, default_value);

 }

 void G1YoungGenSizer::heap_size_changed(size_t new_number_of_heap_regions) {

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

   switch (_sizer_kind) {

     case SizerDefaults:

       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);

       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);

       break;

     case SizerNewSizeOnly:

       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);

       _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);

       break;

     case SizerMaxNewSizeOnly:

       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);

       _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);

       break;

     case SizerMaxAndNewSize:

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

       break;

     case SizerNewRatio:

       _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);

       _max_desired_young_length = _min_desired_young_length;

       break;

     default:

       ShouldNotReachHere();

   }

   assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");

 }

 void G1CollectorPolicy::init() {

   // Set aside an initial future to_space.

   _g1 = G1CollectedHeap::heap();

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

   initialize_gc_policy_counters();

   if (adaptive_young_list_length()) {

     _young_list_fixed_length = 0;

   } else {

     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();

   }

   _free_regions_at_end_of_collection = _g1->free_regions();

   update_young_list_target_length();

   _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;

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

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

   start_incremental_cset_building();

 }

 // Create the jstat counters for the policy.

 void G1CollectorPolicy::initialize_gc_policy_counters() {

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

 }

 bool G1CollectorPolicy::predict_will_fit(size_t young_length,

                                          double base_time_ms,

                                          size_t base_free_regions,

                                          double target_pause_time_ms) {

   if (young_length >= base_free_regions) {

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

     return false;

   }

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

   size_t bytes_to_copy =

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

   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);

   double young_other_time_ms = predict_young_other_time_ms(young_length);

   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;

   if (pause_time_ms > target_pause_time_ms) {

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

     return false;

   }

   size_t free_bytes =

                   (base_free_regions - young_length) * HeapRegion::GrainBytes;

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

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

     return false;

   }

   // success!

   return true;

 }

 void G1CollectorPolicy::record_new_heap_size(size_t new_number_of_regions) {

   // re-calculate the necessary reserve

   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;

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

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

   _reserve_regions = (size_t) ceil(reserve_regions_d);

   _young_gen_sizer->heap_size_changed(new_number_of_regions);

 }

 size_t G1CollectorPolicy::calculate_young_list_desired_min_length(

                                                      size_t base_min_length) {

   size_t desired_min_length = 0;

   if (adaptive_young_list_length()) {

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

       double now_sec = os::elapsedTime();

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

       double alloc_rate_ms = predict_alloc_rate_ms();

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

     } else {

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

     }

   }

   desired_min_length += base_min_length;

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

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

 }

 size_t G1CollectorPolicy::calculate_young_list_desired_max_length() {

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

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

   // effectively don't set this bound.

   return _young_gen_sizer->max_desired_young_length();

 }

 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {

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

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

     // otherwise, use the given value.

     rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);

   }

   // Calculate the absolute and desired min bounds.

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

   size_t base_min_length = recorded_survivor_regions();

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

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

   size_t absolute_min_length = base_min_length + 1;

   size_t desired_min_length =

                      calculate_young_list_desired_min_length(base_min_length);

   if (desired_min_length < absolute_min_length) {

     desired_min_length = absolute_min_length;

   }

   // Calculate the absolute and desired max bounds.

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

   size_t absolute_max_length = 0;

   if (_free_regions_at_end_of_collection > _reserve_regions) {

     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;

   }

   size_t desired_max_length = calculate_young_list_desired_max_length();

   if (desired_max_length > absolute_max_length) {

     desired_max_length = absolute_max_length;

   }

   size_t young_list_target_length = 0;

   if (adaptive_young_list_length()) {

     if (gcs_are_young()) {

       young_list_target_length =

                         calculate_young_list_target_length(rs_lengths,

                                                            base_min_length,

                                                            desired_min_length,

                                                            desired_max_length);

       _rs_lengths_prediction = rs_lengths;

     } else {

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

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

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

     }

   } else {

     if (gcs_are_young()) {

       young_list_target_length = _young_list_fixed_length;

     } else {

       // A bit arbitrary: during mixed GCs we allocate half

       // the young regions to try to add old regions to the CSet.

       young_list_target_length = _young_list_fixed_length / 2;

       // We choose to accept that we might go under the desired min

       // length given that we intentionally ask for a smaller young gen.

       desired_min_length = absolute_min_length;

     }

   }

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

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

   // which is why that test is second.

   if (young_list_target_length > desired_max_length) {

     young_list_target_length = desired_max_length;

   }

   if (young_list_target_length < desired_min_length) {

     young_list_target_length = desired_min_length;

   }

   assert(young_list_target_length > recorded_survivor_regions(),

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

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

   _young_list_target_length = young_list_target_length;

   update_max_gc_locker_expansion();

 }

 size_t

 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,

                                                    size_t base_min_length,

                                                    size_t desired_min_length,

                                                    size_t desired_max_length) {

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

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

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

   if (desired_max_length <= desired_min_length) {

     return desired_min_length;

   }

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

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

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

   // will be reflected in the predictions by the

   // survivor_regions_evac_time prediction.

   assert(desired_min_length > base_min_length, "invariant");

   size_t min_young_length = desired_min_length - base_min_length;

   assert(desired_max_length > base_min_length, "invariant");

   size_t max_young_length = desired_max_length - base_min_length;

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

   double survivor_regions_evac_time = predict_survivor_regions_evac_time();

   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);

   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();

   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);

   double base_time_ms =

     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +

     survivor_regions_evac_time;

   size_t available_free_regions = _free_regions_at_end_of_collection;

   size_t base_free_regions = 0;

   if (available_free_regions > _reserve_regions) {

     base_free_regions = available_free_regions - _reserve_regions;

   }

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

   // makes sense fits within the target pause time.

   if (predict_will_fit(min_young_length, base_time_ms,

                        base_free_regions, target_pause_time_ms)) {

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

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

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

     // a binary search between min_young_length and max_young_length.

     if (predict_will_fit(max_young_length, base_time_ms,

                          base_free_regions, target_pause_time_ms)) {

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

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

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

       min_young_length = max_young_length;

     } else {

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

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

       // length. The loop invariants are:

       //

       // min_young_length < max_young_length

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

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

       //

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

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

       // the middle value between min_young_length and

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

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

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

       assert(min_young_length < max_young_length, "invariant");

       size_t diff = (max_young_length - min_young_length) / 2;

       while (diff > 0) {

         size_t young_length = min_young_length + diff;

         if (predict_will_fit(young_length, base_time_ms,

                              base_free_regions, target_pause_time_ms)) {

           min_young_length = young_length;

         } else {

           max_young_length = young_length;

         }

         assert(min_young_length <  max_young_length, "invariant");

         diff = (max_young_length - min_young_length) / 2;

       }

       // The results is min_young_length which, according to the

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

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

       assert(min_young_length < max_young_length,

              "otherwise we should have discovered that max_young_length "

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

       assert(predict_will_fit(min_young_length, base_time_ms,

                               base_free_regions, target_pause_time_ms),

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

              "fit into the pause target");

       assert(!predict_will_fit(min_young_length + 1, base_time_ms,

                                base_free_regions, target_pause_time_ms),

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

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

     }

   } else {

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

     // target, return it as the result nevertheless.

   }

   return base_min_length + min_young_length;

 }

 double G1CollectorPolicy::predict_survivor_regions_evac_time() {

   double survivor_regions_evac_time = 0.0;

   for (HeapRegion * r = _recorded_survivor_head;

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

        r = r->get_next_young_region()) {

     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);

   }

   return survivor_regions_evac_time;

 }

 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {

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

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

   if (rs_lengths > _rs_lengths_prediction) {

     // add 10% to avoid having to recalculate often

     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;

     update_young_list_target_length(rs_lengths_prediction);

   }

 }

 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,

                                                bool is_tlab,

                                                bool* gc_overhead_limit_was_exceeded) {

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

   return NULL;

 }

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

 // of its generations being fully allocated.

 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,

                                                        bool is_tlab) {

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

   return NULL;

 }

 #ifndef PRODUCT

 bool G1CollectorPolicy::verify_young_ages() {

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

   return

     verify_young_ages(head, _short_lived_surv_rate_group);

   // also call verify_young_ages on any additional surv rate groups

 }

 bool

 G1CollectorPolicy::verify_young_ages(HeapRegion* head,

                                      SurvRateGroup *surv_rate_group) {

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

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

   bool ret = true;

   int prev_age = -1;

   for (HeapRegion* curr = head;

        curr != NULL;

        curr = curr->get_next_young_region()) {

     SurvRateGroup* group = curr->surv_rate_group();

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

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

       ret = false;

     }

     if (surv_rate_group == group) {

       int age = curr->age_in_surv_rate_group();

       if (age < 0) {

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

         ret = false;

       }

       if (age <= prev_age) {

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

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

         ret = false;

       }

       prev_age = age;

     }

   }

   return ret;

 }

 #endif // PRODUCT

 void G1CollectorPolicy::record_full_collection_start() {

   _cur_collection_start_sec = os::elapsedTime();

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

   _g1->set_full_collection();

 }

 void G1CollectorPolicy::record_full_collection_end() {

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

   // since last pause.

   double end_sec = os::elapsedTime();

   double full_gc_time_sec = end_sec - _cur_collection_start_sec;

   double full_gc_time_ms = full_gc_time_sec * 1000.0;

   _all_full_gc_times_ms->add(full_gc_time_ms);

   update_recent_gc_times(end_sec, full_gc_time_ms);

   _g1->clear_full_collection();

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

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

   set_gcs_are_young(true);

   _last_young_gc = false;

   _should_revert_to_young_gcs = false;

   clear_initiate_conc_mark_if_possible();

   clear_during_initial_mark_pause();

   _known_garbage_bytes = 0;

   _known_garbage_ratio = 0.0;

   _in_marking_window = false;

   _in_marking_window_im = false;

   _short_lived_surv_rate_group->start_adding_regions();

   // also call this on any additional surv rate groups

   record_survivor_regions(0, NULL, NULL);

   _free_regions_at_end_of_collection = _g1->free_regions();

   // Reset survivors SurvRateGroup.

   _survivor_surv_rate_group->reset();

   update_young_list_target_length();

   _collectionSetChooser->updateAfterFullCollection();

 }

 void G1CollectorPolicy::record_stop_world_start() {

   _stop_world_start = os::elapsedTime();

 }

 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,

                                                       size_t start_used) {

   if (PrintGCDetails) {

     gclog_or_tty->stamp(PrintGCTimeStamps);

     gclog_or_tty->print("[GC pause");

     gclog_or_tty->print(" (%s)", gcs_are_young() ? "young" : "mixed");

   }

   if (!during_initial_mark_pause()) {

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

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

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

     update_survivors_policy();

   } else {

     // The marking phase has a "we only copy implicitly live

     // objects during marking" invariant. The easiest way to ensure it

     // holds is not to allocate any survivor regions and tenure all

     // objects. In the future we might change this and handle survivor

     // regions specially during marking.

     tenure_all_objects();

   }

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

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

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

   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;

   _all_stop_world_times_ms->add(s_w_t_ms);

   _stop_world_start = 0.0;

   _cur_collection_start_sec = start_time_sec;

   _cur_collection_pause_used_at_start_bytes = start_used;

   _cur_collection_pause_used_regions_at_start = _g1->used_regions();

   _pending_cards = _g1->pending_card_num();

   _max_pending_cards = _g1->max_pending_card_num();

   _bytes_in_collection_set_before_gc = 0;

   _bytes_copied_during_gc = 0;

   YoungList* young_list = _g1->young_list();

   _eden_bytes_before_gc = young_list->eden_used_bytes();

   _survivor_bytes_before_gc = young_list->survivor_used_bytes();

   _capacity_before_gc = _g1->capacity();

 #ifdef DEBUG

   // initialise these to something well known so that we can spot

   // if they are not set properly

   for (int i = 0; i < _parallel_gc_threads; ++i) {

     _par_last_gc_worker_start_times_ms[i] = -1234.0;

     _par_last_ext_root_scan_times_ms[i] = -1234.0;

     _par_last_satb_filtering_times_ms[i] = -1234.0;

     _par_last_update_rs_times_ms[i] = -1234.0;

     _par_last_update_rs_processed_buffers[i] = -1234.0;

     _par_last_scan_rs_times_ms[i] = -1234.0;

     _par_last_obj_copy_times_ms[i] = -1234.0;

     _par_last_termination_times_ms[i] = -1234.0;

     _par_last_termination_attempts[i] = -1234.0;

     _par_last_gc_worker_end_times_ms[i] = -1234.0;

     _par_last_gc_worker_times_ms[i] = -1234.0;

     _par_last_gc_worker_other_times_ms[i] = -1234.0;

   }

 #endif

   for (int i = 0; i < _aux_num; ++i) {

     _cur_aux_times_ms[i] = 0.0;

     _cur_aux_times_set[i] = false;

   }

   // This is initialized to zero here and is set during

   // the evacuation pause if marking is in progress.

   _cur_satb_drain_time_ms = 0.0;

   _last_gc_was_young = false;

   // do that for any other surv rate groups

   _short_lived_surv_rate_group->stop_adding_regions();

   _survivors_age_table.clear();

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

 }

 void G1CollectorPolicy::record_concurrent_mark_init_end(double

                                                    mark_init_elapsed_time_ms) {

   _during_marking = true;

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

   clear_during_initial_mark_pause();

   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;

 }

 void G1CollectorPolicy::record_concurrent_mark_remark_start() {

   _mark_remark_start_sec = os::elapsedTime();

   _during_marking = false;

 }

 void G1CollectorPolicy::record_concurrent_mark_remark_end() {

   double end_time_sec = os::elapsedTime();

   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;

   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);

   _cur_mark_stop_world_time_ms += elapsed_time_ms;

   _prev_collection_pause_end_ms += elapsed_time_ms;

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

 }

 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {

   _mark_cleanup_start_sec = os::elapsedTime();

 }

 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {

   _should_revert_to_young_gcs = false;

   _last_young_gc = true;

   _in_marking_window = false;

 }

 void G1CollectorPolicy::record_concurrent_pause() {

   if (_stop_world_start > 0.0) {

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

     _all_yield_times_ms->add(yield_ms);

   }

 }

 void G1CollectorPolicy::record_concurrent_pause_end() {

 }

 template<class T>

 T sum_of(T* sum_arr, int start, int n, int N) {

   T sum = (T)0;

   for (int i = 0; i < n; i++) {

     int j = (start + i) % N;

     sum += sum_arr[j];

   }

   return sum;

 }

 void G1CollectorPolicy::print_par_stats(int level,

                                         const char* str,

                                         double* data) {

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

   double total = 0.0;

   LineBuffer buf(level);

   buf.append("[%s (ms):", str);

   for (uint i = 0; i < no_of_gc_threads(); ++i) {

     double val = data[i];

     if (val < min)

       min = val;

     if (val > max)

       max = val;

     total += val;

     buf.append("  %3.1lf", val);

   }

   buf.append_and_print_cr("");

   double avg = total / (double) no_of_gc_threads();

   buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",

     avg, min, max, max - min);

 }

 void G1CollectorPolicy::print_par_sizes(int level,

                                         const char* str,

                                         double* data) {

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

   double total = 0.0;

   LineBuffer buf(level);

   buf.append("[%s :", str);

   for (uint i = 0; i < no_of_gc_threads(); ++i) {

     double val = data[i];

     if (val < min)

       min = val;

     if (val > max)

       max = val;

     total += val;

     buf.append(" %d", (int) val);

   }

   buf.append_and_print_cr("");

   double avg = total / (double) no_of_gc_threads();

   buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",

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

 }

 void G1CollectorPolicy::print_stats(int level,

                                     const char* str,

                                     double value) {

   LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);

 }

 void G1CollectorPolicy::print_stats(int level,

                                     const char* str,

                                     int value) {

   LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);

 }

 double G1CollectorPolicy::avg_value(double* data) {

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     double ret = 0.0;

     for (uint i = 0; i < no_of_gc_threads(); ++i) {

       ret += data[i];

     }

     return ret / (double) no_of_gc_threads();

   } else {

     return data[0];

   }

 }

 double G1CollectorPolicy::max_value(double* data) {

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     double ret = data[0];

     for (uint i = 1; i < no_of_gc_threads(); ++i) {

       if (data[i] > ret) {

         ret = data[i];

       }

     }

     return ret;

   } else {

     return data[0];

   }

 }

 double G1CollectorPolicy::sum_of_values(double* data) {

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     double sum = 0.0;

     for (uint i = 0; i < no_of_gc_threads(); i++) {

       sum += data[i];

     }

     return sum;

   } else {

     return data[0];

   }

 }

 double G1CollectorPolicy::max_sum(double* data1, double* data2) {

   double ret = data1[0] + data2[0];

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     for (uint i = 1; i < no_of_gc_threads(); ++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(int no_of_gc_threads) {

   double end_time_sec = os::elapsedTime();

   double elapsed_ms = _last_pause_time_ms;

   bool parallel = G1CollectedHeap::use_parallel_gc_threads();

   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),

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

   size_t rs_size =

             _cur_collection_pause_used_regions_at_start - cset_region_length();

   size_t cur_used_bytes = _g1->used();

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

   bool last_pause_included_initial_mark = false;

   bool update_stats = !_g1->evacuation_failed();

   set_no_of_gc_threads(no_of_gc_threads);

 #ifndef PRODUCT

   if (G1YoungSurvRateVerbose) {

     gclog_or_tty->print_cr("");

     _short_lived_surv_rate_group->print();

     // do that for any other surv rate groups too

   }

 #endif // PRODUCT

   last_pause_included_initial_mark = during_initial_mark_pause();

   if (last_pause_included_initial_mark)

     record_concurrent_mark_init_end(0.0);

   size_t marking_initiating_used_threshold =

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

   if (!_g1->mark_in_progress() && !_last_young_gc) {

     assert(!last_pause_included_initial_mark, "invariant");

     if (cur_used_bytes > marking_initiating_used_threshold) {

       if (cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {

         assert(!during_initial_mark_pause(), "we should not see this here");

         ergo_verbose3(ErgoConcCycles,

                       "request concurrent cycle initiation",

                       ergo_format_reason("occupancy higher than threshold")

                       ergo_format_byte("occupancy")

                       ergo_format_byte_perc("threshold"),

                       cur_used_bytes,

                       marking_initiating_used_threshold,

                       (double) InitiatingHeapOccupancyPercent);

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

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

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

         set_initiate_conc_mark_if_possible();

       } else {

         ergo_verbose2(ErgoConcCycles,

                   "do not request concurrent cycle initiation",

                   ergo_format_reason("occupancy lower than previous occupancy")

                   ergo_format_byte("occupancy")

                   ergo_format_byte("previous occupancy"),

                   cur_used_bytes,

                   _prev_collection_pause_used_at_end_bytes);

       }

     }

   }

   _prev_collection_pause_used_at_end_bytes = cur_used_bytes;

   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,

                           end_time_sec, false);

   // 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;

   // These values are used to update the summary information that is

   // displayed when TraceGen0Time is enabled, and are output as part

   // of the PrintGCDetails output, in the non-parallel case.

   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);

   double satb_filtering_time = avg_value(_par_last_satb_filtering_times_ms);

   double update_rs_time = avg_value(_par_last_update_rs_times_ms);

   double update_rs_processed_buffers =

     sum_of_values(_par_last_update_rs_processed_buffers);

   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);

   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);

   double termination_time = avg_value(_par_last_termination_times_ms);

   double known_time = ext_root_scan_time +

                       satb_filtering_time +

                       update_rs_time +

                       scan_rs_time +

                       obj_copy_time;

   double other_time_ms = elapsed_ms;

   // Subtract the SATB drain time. It's initialized to zero at the

   // start of the pause and is updated during the pause if marking

   // is in progress.

   other_time_ms -= _cur_satb_drain_time_ms;

   if (parallel) {

     other_time_ms -= _cur_collection_par_time_ms;

   } else {

     other_time_ms -= known_time;

   }

   // Subtract the time taken to clean the card table from the

   // current value of "other time"

   other_time_ms -= _cur_clear_ct_time_ms;

   // Subtract the time spent completing marking in the collection

   // set. Note if marking is not in progress during the pause

   // the value of _mark_closure_time_ms will be zero.

   other_time_ms -= _mark_closure_time_ms;

   // TraceGen0Time and TraceGen1Time summary info updating.

   _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);

     MainBodySummary* body_summary = _summary->main_body_summary();

     assert(body_summary != NULL, "should not be null!");

     // This will be non-zero iff marking is currently in progress (i.e.

     // _g1->mark_in_progress() == true) and the currrent pause was not

     // an initial mark pause. Since the body_summary items are NumberSeqs,

     // however, they have to be consistent and updated in lock-step with

     // each other. Therefore we unconditionally record the SATB drain

     // time - even if it's zero.

     body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);

     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);

     body_summary->record_satb_filtering_time_ms(satb_filtering_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_termination_time_ms(termination_time);

       double parallel_known_time = known_time + termination_time;

       double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;

       body_summary->record_parallel_other_time_ms(parallel_other_time);

     }

     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);

     body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);

     // We exempt parallel collection from this check because Alloc Buffer

     // fragmentation can produce negative collections.  Same with evac

     // failure.

     // Further, we're now always doing parallel collection.  But I'm still

     // leaving this here as a placeholder for a more precise assertion later.

     // (DLD, 10/05.

     assert((true || parallel)

            || _g1->evacuation_failed()

            || surviving_bytes <= _collection_set_bytes_used_before,

            "Or else negative collection!");

     // 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;

     }

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

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

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

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

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

     // given that humongous object allocations do not really affect

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

     // place we can safely ignore them here.

     size_t regions_allocated = eden_cset_region_length();

     double alloc_rate_ms = (double) regions_allocated / app_time_ms;

     _alloc_rate_ms_seq->add(alloc_rate_ms);

     double interval_ms =

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

     update_recent_gc_times(end_time_sec, elapsed_ms);

     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;

     if (recent_avg_pause_time_ratio() < 0.0 ||

         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {

 #ifndef PRODUCT

       // Dump info to allow post-facto debugging

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

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

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

       _recent_gc_times_ms->dump();

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

       _recent_prev_end_times_for_all_gcs_sec->dump();

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

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

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

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

 #endif  // !PRODUCT

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

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

       if (_recent_avg_pause_time_ratio < 0.0) {

         _recent_avg_pause_time_ratio = 0.0;

       } else {

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

         _recent_avg_pause_time_ratio = 1.0;

       }

     }

   }

   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]);

     }

   }

   // PrintGCDetails output

   if (PrintGCDetails) {

     bool print_marking_info =

       _g1->mark_in_progress() && !last_pause_included_initial_mark;

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

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

                            elapsed_ms / 1000.0);

     if (parallel) {

       print_stats(1, "Parallel Time", _cur_collection_par_time_ms);

       print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);

       print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);

       if (print_marking_info) {

         print_par_stats(2, "SATB Filtering", _par_last_satb_filtering_times_ms);

       }

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

       print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);

       print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);

       print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);

       print_par_stats(2, "Termination", _par_last_termination_times_ms);

       print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);

       print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);

       for (int i = 0; i < _parallel_gc_threads; i++) {

         _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];

         double worker_known_time = _par_last_ext_root_scan_times_ms[i] +

                                    _par_last_satb_filtering_times_ms[i] +

                                    _par_last_update_rs_times_ms[i] +

                                    _par_last_scan_rs_times_ms[i] +

                                    _par_last_obj_copy_times_ms[i] +

                                    _par_last_termination_times_ms[i];

         _par_last_gc_worker_other_times_ms[i] = _cur_collection_par_time_ms - worker_known_time;

       }

       print_par_stats(2, "GC Worker", _par_last_gc_worker_times_ms);

       print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);

     } else {

       print_stats(1, "Ext Root Scanning", ext_root_scan_time);

       if (print_marking_info) {

         print_stats(1, "SATB Filtering", satb_filtering_time);

       }

       print_stats(1, "Update RS", update_rs_time);

       print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);

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

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

     }

     if (print_marking_info) {

       print_stats(1, "Complete CSet Marking", _mark_closure_time_ms);

     }

     print_stats(1, "Clear CT", _cur_clear_ct_time_ms);

 #ifndef PRODUCT

     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);

     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);

     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);

     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);

     if (_num_cc_clears > 0) {

       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));

     }

 #endif

     print_stats(1, "Other", other_time_ms);

     print_stats(2, "Choose CSet",

                    (_recorded_young_cset_choice_time_ms +

                     _recorded_non_young_cset_choice_time_ms));

     print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);

     print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);

     print_stats(2, "Free CSet",

                    (_recorded_young_free_cset_time_ms +

                     _recorded_non_young_free_cset_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]);

       }

     }

   }

   // Update the efficiency-since-mark vars.

   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;

   if (elapsed_ms < MIN_TIMER_GRANULARITY) {

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

     // granularity. Some Linuxes are the usual culprits.

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

     proc_ms = 1.0;

   }

   double cur_efficiency = (double) freed_bytes / proc_ms;

   bool new_in_marking_window = _in_marking_window;

   bool new_in_marking_window_im = false;

   if (during_initial_mark_pause()) {

     new_in_marking_window = true;

     new_in_marking_window_im = true;

   }

   if (_last_young_gc) {

     if (!last_pause_included_initial_mark) {

       ergo_verbose2(ErgoMixedGCs,

                     "start mixed GCs",

                     ergo_format_byte_perc("known garbage"),

                     _known_garbage_bytes, _known_garbage_ratio * 100.0);

       set_gcs_are_young(false);

     } else {

       ergo_verbose0(ErgoMixedGCs,

                     "do not start mixed GCs",

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

     }

     _last_young_gc = false;

   }

   if (!_last_gc_was_young) {

     if (_should_revert_to_young_gcs) {

       ergo_verbose2(ErgoMixedGCs,

                     "end mixed GCs",

                     ergo_format_reason("mixed GCs end requested")

                     ergo_format_byte_perc("known garbage"),

                     _known_garbage_bytes, _known_garbage_ratio * 100.0);

       set_gcs_are_young(true);

     } else if (_known_garbage_ratio < 0.05) {

       ergo_verbose3(ErgoMixedGCs,

                "end mixed GCs",

                ergo_format_reason("known garbage percent lower than threshold")

                ergo_format_byte_perc("known garbage")

                ergo_format_perc("threshold"),

                _known_garbage_bytes, _known_garbage_ratio * 100.0,

                0.05 * 100.0);

       set_gcs_are_young(true);

     } else if (adaptive_young_list_length() &&

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

       ergo_verbose5(ErgoMixedGCs,

                     "end mixed GCs",

                     ergo_format_reason("current GC efficiency lower than "

                                        "predicted young GC efficiency")

                     ergo_format_double("GC efficiency factor")

                     ergo_format_double("current GC efficiency")

                     ergo_format_double("predicted young GC efficiency")

                     ergo_format_byte_perc("known garbage"),

                     get_gc_eff_factor(), cur_efficiency,

                     predict_young_gc_eff(),

                     _known_garbage_bytes, _known_garbage_ratio * 100.0);

       set_gcs_are_young(true);

     }

   }

   _should_revert_to_young_gcs = false;

   if (_last_gc_was_young && !_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

   if (update_stats) {

     double pause_time_ms = elapsed_ms;

     size_t diff = 0;

     if (_max_pending_cards >= _pending_cards)

       diff = _max_pending_cards - _pending_cards;

     _pending_card_diff_seq->add((double) diff);

     double cost_per_card_ms = 0.0;

     if (_pending_cards > 0) {

       cost_per_card_ms = update_rs_time / (double) _pending_cards;

       _cost_per_card_ms_seq->add(cost_per_card_ms);

     }

     size_t cards_scanned = _g1->cards_scanned();

     double cost_per_entry_ms = 0.0;

     if (cards_scanned > 10) {

       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;

       if (_last_gc_was_young) {

         _cost_per_entry_ms_seq->add(cost_per_entry_ms);

       } else {

         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);

       }

     }

     if (_max_rs_lengths > 0) {

       double cards_per_entry_ratio =

         (double) cards_scanned / (double) _max_rs_lengths;

       if (_last_gc_was_young) {

         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);

       } else {

         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);

       }

     }

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

     // smaller than _recorded_rs_lengths which was causing

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

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

     // _inc_cset_recorded_rs_lengths field which the code below guards

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

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

     // _inc_cset_recorded_rs_lengths might still end up somewhat

     // inaccurate. The concurrent refinement thread calculates an

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

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

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

     // conditional below just in case.

     size_t rs_length_diff = 0;

     if (_max_rs_lengths > _recorded_rs_lengths) {

       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;

     }

     _rs_length_diff_seq->add((double) rs_length_diff);

     size_t copied_bytes = surviving_bytes;

     double cost_per_byte_ms = 0.0;

     if (copied_bytes > 0) {

       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;

       if (_in_marking_window) {

         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);

       } else {

         _cost_per_byte_ms_seq->add(cost_per_byte_ms);

       }

     }

     double all_other_time_ms = pause_time_ms -

       (update_rs_time + scan_rs_time + obj_copy_time +

        _mark_closure_time_ms + termination_time);

     double young_other_time_ms = 0.0;

     if (young_cset_region_length() > 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) young_cset_region_length());

     }

     double non_young_other_time_ms = 0.0;

     if (old_cset_region_length() > 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) old_cset_region_length());

     }

     double constant_other_time_ms = all_other_time_ms -

       (young_other_time_ms + non_young_other_time_ms);

     _constant_other_time_ms_seq->add(constant_other_time_ms);

     double survival_ratio = 0.0;

     if (_bytes_in_collection_set_before_gc > 0) {

       survival_ratio = (double) _bytes_copied_during_gc /

                                    (double) _bytes_in_collection_set_before_gc;

     }

     _pending_cards_seq->add((double) _pending_cards);

     _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;

   }

   _in_marking_window = new_in_marking_window;

   _in_marking_window_im = new_in_marking_window_im;

   _free_regions_at_end_of_collection = _g1->free_regions();

   update_young_list_target_length();

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

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

   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);

   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

 }

 #define EXT_SIZE_FORMAT "%d%s"

 #define EXT_SIZE_PARAMS(bytes)                                  \

   byte_size_in_proper_unit((bytes)),                            \

   proper_unit_for_byte_size((bytes))

 void G1CollectorPolicy::print_heap_transition() {

   if (PrintGCDetails) {

     YoungList* young_list = _g1->young_list();

     size_t eden_bytes = young_list->eden_used_bytes();

     size_t survivor_bytes = young_list->survivor_used_bytes();

     size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;

     size_t used = _g1->used();

     size_t capacity = _g1->capacity();

     size_t eden_capacity =

       (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;

     gclog_or_tty->print_cr(

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

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

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

       EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",

       EXT_SIZE_PARAMS(_eden_bytes_before_gc),

       EXT_SIZE_PARAMS(_prev_eden_capacity),

       EXT_SIZE_PARAMS(eden_bytes),

       EXT_SIZE_PARAMS(eden_capacity),

       EXT_SIZE_PARAMS(_survivor_bytes_before_gc),

       EXT_SIZE_PARAMS(survivor_bytes),

       EXT_SIZE_PARAMS(used_before_gc),

       EXT_SIZE_PARAMS(_capacity_before_gc),

       EXT_SIZE_PARAMS(used),

       EXT_SIZE_PARAMS(capacity));

     _prev_eden_capacity = eden_capacity;

   } else if (PrintGC) {

     _g1->print_size_transition(gclog_or_tty,

                                _cur_collection_pause_used_at_start_bytes,

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

   }

 }

 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,

                                                      double update_rs_processed_buffers,

                                                      double goal_ms) {

   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

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

   if (G1UseAdaptiveConcRefinement) {

     const int k_gy = 3, k_gr = 6;

     const double inc_k = 1.1, dec_k = 0.9;

     int g = cg1r->green_zone();

     if (update_rs_time > goal_ms) {

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

     } else {

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

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

       }

     }

     // Change the refinement threads params

     cg1r->set_green_zone(g);

     cg1r->set_yellow_zone(g * k_gy);

     cg1r->set_red_zone(g * k_gr);

     cg1r->reinitialize_threads();

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

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

                                     cg1r->yellow_zone());

     // Change the barrier params

     dcqs.set_process_completed_threshold(processing_threshold);

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

   }

   int curr_queue_size = dcqs.completed_buffers_num();

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

     dcqs.set_completed_queue_padding(curr_queue_size);

   } else {

     dcqs.set_completed_queue_padding(0);

   }

   dcqs.notify_if_necessary();

 }

 double

 G1CollectorPolicy::

 predict_young_collection_elapsed_time_ms(size_t adjustment) {

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

   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   size_t young_num = g1h->young_list()->length();

   if (young_num == 0)

     return 0.0;

   young_num += adjustment;

   size_t pending_cards = predict_pending_cards();

   size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +

                       predict_rs_length_diff();

   size_t card_num;

   if (gcs_are_young()) {

     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 (gcs_are_young()) {

     card_num = predict_young_card_num(rs_length);

   } else {

     card_num = predict_non_young_card_num(rs_length);

   }

   return predict_base_elapsed_time_ms(pending_cards, card_num);

 }

 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 (gcs_are_young()) {

     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::init_cset_region_lengths(size_t eden_cset_region_length,

                                           size_t survivor_cset_region_length) {

   _eden_cset_region_length     = eden_cset_region_length;

   _survivor_cset_region_length = survivor_cset_region_length;

   _old_cset_region_length      = 0;

 }

 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {

   _recorded_rs_lengths = rs_lengths;

 }

 void G1CollectorPolicy::check_if_region_is_too_expensive(double

                                                            predicted_time_ms) {

   // I don't think we need to do this when in young GC mode since

   // marking will be initiated next time we hit the soft limit anyway...

   if (predicted_time_ms > _expensive_region_limit_ms) {

     ergo_verbose2(ErgoMixedGCs,

               "request mixed GCs end",

               ergo_format_reason("predicted region time higher than threshold")

               ergo_format_ms("predicted region time")

               ergo_format_ms("threshold"),

               predicted_time_ms, _expensive_region_limit_ms);

     // no point in doing another mixed GC

     _should_revert_to_young_gcs = true;

   }

 }

 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,

                                                double elapsed_ms) {

   _recent_gc_times_ms->add(elapsed_ms);

   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);

   _prev_collection_pause_end_ms = end_time_sec * 1000.0;

 }

 size_t G1CollectorPolicy::expansion_amount() {

   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;

   double threshold = _gc_overhead_perc;

   if (recent_gc_overhead > threshold) {

     // We will double the existing space, or take

     // G1ExpandByPercentOfAvailable % of the available expansion

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

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

     const size_t min_expand_bytes = 1*M;

     size_t reserved_bytes = _g1->max_capacity();

     size_t committed_bytes = _g1->capacity();

     size_t uncommitted_bytes = reserved_bytes - committed_bytes;

     size_t expand_bytes;

     size_t expand_bytes_via_pct =

       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;

     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);

     expand_bytes = MAX2(expand_bytes, min_expand_bytes);

     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);

     ergo_verbose5(ErgoHeapSizing,

                   "attempt heap expansion",

                   ergo_format_reason("recent GC overhead higher than "

                                      "threshold after GC")

                   ergo_format_perc("recent GC overhead")

                   ergo_format_perc("threshold")

                   ergo_format_byte("uncommitted")

                   ergo_format_byte_perc("calculated expansion amount"),

                   recent_gc_overhead, threshold,

                   uncommitted_bytes,

                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);

     return expand_bytes;

   } else {

     return 0;

   }

 }

 class CountCSClosure: public HeapRegionClosure {

   G1CollectorPolicy* _g1_policy;

 public:

   CountCSClosure(G1CollectorPolicy* g1_policy) :

     _g1_policy(g1_policy) {}

   bool doHeapRegion(HeapRegion* r) {

     _g1_policy->_bytes_in_collection_set_before_gc += r->used();

     return false;

   }

 };

 void G1CollectorPolicy::count_CS_bytes_used() {

   CountCSClosure cs_closure(this);

   _g1->collection_set_iterate(&cs_closure);

 }

 void G1CollectorPolicy::print_summary(int level,

                                       const char* str,

                                       NumberSeq* seq) const {

   double sum = seq->sum();

   LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",

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

 }

 void G1CollectorPolicy::print_summary_sd(int level,

                                          const char* str,

                                          NumberSeq* seq) const {

   print_summary(level, str, seq);

   LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",

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

 }

 void G1CollectorPolicy::check_other_times(int level,

                                         NumberSeq* other_times_ms,

                                         NumberSeq* calc_other_times_ms) const {

   bool should_print = false;

   LineBuffer buf(level + 2);

   double max_sum = MAX2(fabs(other_times_ms->sum()),

                         fabs(calc_other_times_ms->sum()));

   double min_sum = MIN2(fabs(other_times_ms->sum()),

                         fabs(calc_other_times_ms->sum()));

   double sum_ratio = max_sum / min_sum;

   if (sum_ratio > 1.1) {

     should_print = true;

     buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");

   }

   double max_avg = MAX2(fabs(other_times_ms->avg()),

                         fabs(calc_other_times_ms->avg()));

   double min_avg = MIN2(fabs(other_times_ms->avg()),

                         fabs(calc_other_times_ms->avg()));

   double avg_ratio = max_avg / min_avg;

   if (avg_ratio > 1.1) {

     should_print = true;

     buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");

   }

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

     buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");

   }

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

     buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");

   }

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

     should_print = true;

     buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");

   }

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

     should_print = true;

     buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");

   }

   if (should_print)

     print_summary(level, "Other(Calc)", calc_other_times_ms);

 }

 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {

   bool parallel = G1CollectedHeap::use_parallel_gc_threads();

   MainBodySummary*    body_summary = summary->main_body_summary();

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

     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());

     if (body_summary != NULL) {

       if (parallel) {

         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());

         print_summary(2, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());

         print_summary(2, "SATB Filtering", body_summary->get_satb_filtering_seq());

         print_summary(2, "Update RS", body_summary->get_update_rs_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, "Parallel Other", body_summary->get_parallel_other_seq());

         {

           NumberSeq* other_parts[] = {

             body_summary->get_ext_root_scan_seq(),

             body_summary->get_satb_filtering_seq(),

             body_summary->get_update_rs_seq(),

             body_summary->get_scan_rs_seq(),

             body_summary->get_obj_copy_seq(),

             body_summary->get_termination_seq()

           };

           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),

                                         6, other_parts);

           check_other_times(2, body_summary->get_parallel_other_seq(),

                             &calc_other_times_ms);

         }

       } else {

         print_summary(1, "Ext Root Scanning", body_summary->get_ext_root_scan_seq());

         print_summary(1, "SATB Filtering", body_summary->get_satb_filtering_seq());

         print_summary(1, "Update RS", body_summary->get_update_rs_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, "Mark Closure", body_summary->get_mark_closure_seq());

     print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());

     print_summary(1, "Other", summary->get_other_seq());

     {

       if (body_summary != NULL) {

         NumberSeq calc_other_times_ms;

         if (parallel) {

           // parallel

           NumberSeq* other_parts[] = {

             body_summary->get_satb_drain_seq(),

             body_summary->get_parallel_seq(),

             body_summary->get_clear_ct_seq()

           };

           calc_other_times_ms = NumberSeq(summary->get_total_seq(),

                                                 3, other_parts);

         } else {

           // serial

           NumberSeq* other_parts[] = {

             body_summary->get_satb_drain_seq(),

             body_summary->get_update_rs_seq(),

             body_summary->get_ext_root_scan_seq(),

             body_summary->get_satb_filtering_seq(),

             body_summary->get_scan_rs_seq(),

             body_summary->get_obj_copy_seq()

           };

           calc_other_times_ms = NumberSeq(summary->get_total_seq(),

                                                 6, other_parts);

         }

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

       }

     }

   } else {

     LineBuffer(1).append_and_print_cr("none");

   }

   LineBuffer(0).append_and_print_cr("");

 }

 void G1CollectorPolicy::print_tracing_info() const {

   if (TraceGen0Time) {

     gclog_or_tty->print_cr("ALL PAUSES");

     print_summary_sd(0, "Total", _all_pause_times_ms);

     gclog_or_tty->print_cr("");

     gclog_or_tty->print_cr("");

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

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

     gclog_or_tty->print_cr("");

     gclog_or_tty->print_cr("EVACUATION PAUSES");

     print_summary(_summary);

     gclog_or_tty->print_cr("MISC");

     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);

     print_summary_sd(0, "Yields", _all_yield_times_ms);

     for (int i = 0; i < _aux_num; ++i) {

       if (_all_aux_times_ms[i].num() > 0) {

         char buffer[96];

         sprintf(buffer, "Aux%d", i);

         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);

       }

     }

   }

   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

 }

 #ifndef PRODUCT

 // for debugging, bit of a hack...

 static char*

 region_num_to_mbs(int length) {

   static char buffer[64];

   double bytes = (double) (length * HeapRegion::GrainBytes);

   double mbs = bytes / (double) (1024 * 1024);

   sprintf(buffer, "%7.2lfMB", mbs);

   return buffer;

 }

 #endif // PRODUCT

 size_t G1CollectorPolicy::max_regions(int purpose) {

   switch (purpose) {

     case GCAllocForSurvived:

       return _max_survivor_regions;

     case GCAllocForTenured:

       return REGIONS_UNLIMITED;

     default:

       ShouldNotReachHere();

       return REGIONS_UNLIMITED;

   };

 }

 void G1CollectorPolicy::update_max_gc_locker_expansion() {

   size_t expansion_region_num = 0;

   if (GCLockerEdenExpansionPercent > 0) {

     double perc = (double) GCLockerEdenExpansionPercent / 100.0;

     double expansion_region_num_d = perc * (double) _young_list_target_length;

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

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

     expansion_region_num = (size_t) ceil(expansion_region_num_d);

   } else {

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

   }

   _young_list_max_length = _young_list_target_length + expansion_region_num;

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

 }

 // Calculates survivor space parameters.

 void G1CollectorPolicy::update_survivors_policy() {

   double max_survivor_regions_d =

                  (double) _young_list_target_length / (double) SurvivorRatio;

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

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

   _max_survivor_regions = (size_t) ceil(max_survivor_regions_d);

   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(

         HeapRegion::GrainWords * _max_survivor_regions);

 }

 #ifndef PRODUCT

 class HRSortIndexIsOKClosure: public HeapRegionClosure {

   CollectionSetChooser* _chooser;

 public:

   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :

     _chooser(chooser) {}

   bool doHeapRegion(HeapRegion* r) {

     if (!r->continuesHumongous()) {

       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");

     }

     return false;

   }

 };

 bool G1CollectorPolicy::assertMarkedBytesDataOK() {

   HRSortIndexIsOKClosure cl(_collectionSetChooser);

   _g1->heap_region_iterate(&cl);

   return true;

 }

 #endif

 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(

                                                      GCCause::Cause gc_cause) {

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

   if (!during_cycle) {

     ergo_verbose1(ErgoConcCycles,

                   "request concurrent cycle initiation",

                   ergo_format_reason("requested by GC cause")

                   ergo_format_str("GC cause"),

                   GCCause::to_string(gc_cause));

     set_initiate_conc_mark_if_possible();

     return true;

   } else {

     ergo_verbose1(ErgoConcCycles,

                   "do not request concurrent cycle initiation",

                   ergo_format_reason("concurrent cycle already in progress")

                   ergo_format_str("GC cause"),

                   GCCause::to_string(gc_cause));

     return false;

   }

 }

 void

 G1CollectorPolicy::decide_on_conc_mark_initiation() {

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

   // initial-mark pause.

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

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

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

   // initial-mark pause).

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

   if (initiate_conc_mark_if_possible()) {

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

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

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

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

     if (!during_cycle) {

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

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

       // initiate a new cycle.

       set_during_initial_mark_pause();

       // We do not allow mixed GCs during marking.

       if (!gcs_are_young()) {

         set_gcs_are_young(true);

         ergo_verbose0(ErgoMixedGCs,

                       "end mixed GCs",

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

       }

       // And we can now clear initiate_conc_mark_if_possible() as

       // we've already acted on it.

       clear_initiate_conc_mark_if_possible();

       ergo_verbose0(ErgoConcCycles,

                   "initiate concurrent cycle",

                   ergo_format_reason("concurrent cycle initiation requested"));

     } else {

       // The concurrent marking thread is still finishing up the

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

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

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

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

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

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

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

       // periodically yields while clearing the next marking bitmap

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

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

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

       ergo_verbose0(ErgoConcCycles,

                     "do not initiate concurrent cycle",

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

     }

   }

 }

 class KnownGarbageClosure: public HeapRegionClosure {

   CollectionSetChooser* _hrSorted;

 public:

   KnownGarbageClosure(CollectionSetChooser* hrSorted) :

     _hrSorted(hrSorted)

   {}

   bool doHeapRegion(HeapRegion* r) {

     // We only include humongous regions in collection

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

     // unreachable.

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

     if (r->is_marked()) {

       // We don't include humongous regions in collection

       // sets because we collect them immediately at the end of a marking

       // cycle.  We also don't include young regions because we *must*

       // include them in the next collection pause.

       if (!r->isHumongous() && !r->is_young()) {

         _hrSorted->addMarkedHeapRegion(r);

       }

     }

     return false;

   }

 };

 class ParKnownGarbageHRClosure: public HeapRegionClosure {

   CollectionSetChooser* _hrSorted;

   jint _marked_regions_added;

   jint _chunk_size;

   jint _cur_chunk_idx;

   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)

   int _worker;

   int _invokes;

   void get_new_chunk() {

     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);

     _cur_chunk_end = _cur_chunk_idx + _chunk_size;

   }

   void add_region(HeapRegion* r) {

     if (_cur_chunk_idx == _cur_chunk_end) {

       get_new_chunk();

     }

     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");

     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);

     _marked_regions_added++;

     _cur_chunk_idx++;

   }

 public:

   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,

                            jint chunk_size,

                            int worker) :

     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),

     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),

     _invokes(0)

   {}

   bool doHeapRegion(HeapRegion* r) {

     // We only include humongous regions in collection

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

     // unreachable.

     _invokes++;

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

     if (r->is_marked()) {

       // We don't include humongous regions in collection

       // sets because we collect them immediately at the end of a marking

       // cycle.

       // We also do not include young regions in collection sets

       if (!r->isHumongous() && !r->is_young()) {

         add_region(r);

       }

     }

     return false;

   }

   jint marked_regions_added() { return _marked_regions_added; }

   int invokes() { return _invokes; }

 };

 class ParKnownGarbageTask: public AbstractGangTask {

   CollectionSetChooser* _hrSorted;

   jint _chunk_size;

   G1CollectedHeap* _g1;

 public:

   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :

     AbstractGangTask("ParKnownGarbageTask"),

     _hrSorted(hrSorted), _chunk_size(chunk_size),

     _g1(G1CollectedHeap::heap())

   {}

   void work(uint worker_id) {

     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted,

                                                _chunk_size,

                                                worker_id);

     // Back to zero for the claim value.

     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,

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

                                          HeapRegion::InitialClaimValue);

     jint regions_added = parKnownGarbageCl.marked_regions_added();

     _hrSorted->incNumMarkedHeapRegions(regions_added);

     if (G1PrintParCleanupStats) {

       gclog_or_tty->print_cr("     Thread %d called %d times, added %d regions to list.",

                  worker_id, parKnownGarbageCl.invokes(), regions_added);

     }

   }

 };

 void

 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {

   double start_sec;

   if (G1PrintParCleanupStats) {

     start_sec = os::elapsedTime();

   }

   _collectionSetChooser->clearMarkedHeapRegions();

   double clear_marked_end_sec;

   if (G1PrintParCleanupStats) {

     clear_marked_end_sec = os::elapsedTime();

     gclog_or_tty->print_cr("  clear marked regions: %8.3f ms.",

                            (clear_marked_end_sec - start_sec) * 1000.0);

   }

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     const size_t OverpartitionFactor = 4;

     size_t WorkUnit;

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

     // causes some assertion failures when the total number of

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

     // Should the original code also be fixed?

     if (no_of_gc_threads > 0) {

       const size_t MinWorkUnit =

         MAX2(_g1->n_regions() / no_of_gc_threads, (size_t) 1U);

       WorkUnit =

         MAX2(_g1->n_regions() / (no_of_gc_threads * OverpartitionFactor),

              MinWorkUnit);

     } else {

       assert(no_of_gc_threads > 0,

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

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

       const size_t MinWorkUnit =

         MAX2(_g1->n_regions() / ParallelGCThreads, (size_t) 1U);

       WorkUnit =

         MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),

              MinWorkUnit);

     }

     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),

                                                              WorkUnit);

     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,

                                             (int) WorkUnit);

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

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

            "sanity check");

   } else {

     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);

     _g1->heap_region_iterate(&knownGarbagecl);

   }

   double known_garbage_end_sec;

   if (G1PrintParCleanupStats) {

     known_garbage_end_sec = os::elapsedTime();

     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",

                       (known_garbage_end_sec - clear_marked_end_sec) * 1000.0);

   }

   _collectionSetChooser->sortMarkedHeapRegions();

   double end_sec = os::elapsedTime();

   if (G1PrintParCleanupStats) {

     gclog_or_tty->print_cr("  sorting: %8.3f ms.",

                            (end_sec - known_garbage_end_sec) * 1000.0);

   }

   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;

   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);

   _cur_mark_stop_world_time_ms += elapsed_time_ms;

   _prev_collection_pause_end_ms += elapsed_time_ms;

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

 }

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

 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {

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

   assert(!hr->is_young(), "non-incremental add of young region");

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

   hr->set_in_collection_set(true);

   hr->set_next_in_collection_set(_collection_set);

   _collection_set = hr;

   _collection_set_bytes_used_before += hr->used();

   _g1->register_region_with_in_cset_fast_test(hr);

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

   _recorded_rs_lengths += rs_length;

   _old_cset_region_length += 1;

 }

 // Initialize the per-collection-set information

 void G1CollectorPolicy::start_incremental_cset_building() {

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

   _inc_cset_head = NULL;

   _inc_cset_tail = NULL;

   _inc_cset_bytes_used_before = 0;

   _inc_cset_max_finger = 0;

   _inc_cset_recorded_rs_lengths = 0;

   _inc_cset_recorded_rs_lengths_diffs = 0;

   _inc_cset_predicted_elapsed_time_ms = 0.0;

   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;

   _inc_cset_build_state = Active;

 }

 void G1CollectorPolicy::finalize_incremental_cset_building() {

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

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

   // The two "main" fields, _inc_cset_recorded_rs_lengths and

   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread

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

   // concurrent refinement thread that samples the young RSet lengths

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

   // the "main" fields.

   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {

     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;

   } else {

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

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

     // sample their size concurrently with other threads updating them

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

     // could make the calculations somewhat inaccurate.

     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);

     if (_inc_cset_recorded_rs_lengths >= diffs) {

       _inc_cset_recorded_rs_lengths -= diffs;

     } else {

       _inc_cset_recorded_rs_lengths = 0;

     }

   }

   _inc_cset_predicted_elapsed_time_ms +=

                                      _inc_cset_predicted_elapsed_time_ms_diffs;

   _inc_cset_recorded_rs_lengths_diffs = 0;

   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;

 }

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

   // This routine is used when:

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

   //   evacuation pause,

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

   //   when it is retired, and

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

   //   incremental cset via young list RSet sampling.

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

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

   // retiring the current allocation region) or a concurrent

   // refine thread (RSet sampling).

   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);

   size_t used_bytes = hr->used();

   _inc_cset_recorded_rs_lengths += rs_length;

   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;

   _inc_cset_bytes_used_before += used_bytes;

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

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

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

   // rset sampling code

   hr->set_recorded_rs_length(rs_length);

   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);

 }

 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,

                                                      size_t new_rs_length) {

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

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

   assert(!SafepointSynchronize::is_at_safepoint(),

                                                "should not be at a safepoint");

   // We could have updated _inc_cset_recorded_rs_lengths and

   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do

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

   // refinement thread, potentially concurrently with a mutator thread

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

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

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

   // fields at the start of a GC.

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

   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;

   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;

   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();

   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);

   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;

   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;

   hr->set_recorded_rs_length(new_rs_length);

   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);

 }

 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {

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

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

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

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

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

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

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

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

   // by the Young List sampling code.

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

   add_to_incremental_cset_info(hr, rs_length);

   HeapWord* hr_end = hr->end();

   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);

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

   hr->set_in_collection_set(true);

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

   _g1->register_region_with_in_cset_fast_test(hr);

 }

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

 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {

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

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

   // Do the 'common' stuff

   add_region_to_incremental_cset_common(hr);

   // Now add the region at the right hand side

   if (_inc_cset_tail == NULL) {

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

     _inc_cset_head = hr;

   } else {

     _inc_cset_tail->set_next_in_collection_set(hr);

   }

   _inc_cset_tail = hr;

 }

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

 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {

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

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

   // Do the 'common' stuff

   add_region_to_incremental_cset_common(hr);

   // Add the region at the left hand side

   hr->set_next_in_collection_set(_inc_cset_head);

   if (_inc_cset_head == NULL) {

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

     _inc_cset_tail = hr;

   }

   _inc_cset_head = hr;

 }

 #ifndef PRODUCT

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

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

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

   HeapRegion* csr = list_head;

   while (csr != NULL) {

     HeapRegion* next = csr->next_in_collection_set();

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

     st->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "

                  "age: %4d, y: %d, surv: %d",

                         csr->bottom(), csr->end(),

                         csr->top(),

                         csr->prev_top_at_mark_start(),

                         csr->next_top_at_mark_start(),

                         csr->top_at_conc_mark_count(),

                         csr->age_in_surv_rate_group_cond(),

                         csr->is_young(),

                         csr->is_survivor());

     csr = next;

   }

 }

 #endif // !PRODUCT

 void G1CollectorPolicy::choose_collection_set(double target_pause_time_ms) {

   // Set this here - in case we're not doing young collections.

   double non_young_start_time_sec = os::elapsedTime();

   YoungList* young_list = _g1->young_list();