jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@c33825b68624 (annotated)

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@c33825b68624 (annotated)

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

Wed, 02 Feb 2011 10:41:20 -0800

author: johnc
date: Wed, 02 Feb 2011 10:41:20 -0800
changeset 2504: c33825b68624
parent 2472: 0fa27f37d4d4
child 2645: c93aa6caa02f
permissions: -rw-r--r--

6923430: G1: assert(res != 0,"This should have worked.")
7007446: G1: expand the heap with a single step, not one region at a time
Summary: Changed G1CollectedHeap::expand() to expand the committed space by calling VirtualSpace::expand_by() once rather than for every region in the expansion amount. This allows the success or failure of the expansion to be determined before creating any heap regions. Introduced a develop flag G1ExitOnExpansionFailure (false by default) that, when true, will exit the VM if the expansion of the committed space fails. Finally G1CollectedHeap::expand() returns a status back to it's caller so that the caller knows whether to attempt the allocation.
Reviewed-by: brutisso, tonyp

 /*
  * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/g1/concurrentG1Refine.hpp"
 #include "gc_implementation/g1/concurrentMark.hpp"
 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
 #include "gc_implementation/shared/gcPolicyCounters.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/java.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "utilities/debug.hpp"
 #define PREDICTIONS_VERBOSE 0
 // <NEW PREDICTION>
 // Different defaults for different number of GC threads
 // They were chosen by running GCOld and SPECjbb on debris with different
 //   numbers of GC threads and choosing them based on the results
 // all the same
 static double rs_length_diff_defaults[] = {
 .0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
 };
 static double cost_per_card_ms_defaults[] = {
 .01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
 };
 // all the same
 static double fully_young_cards_per_entry_ratio_defaults[] = {
 .0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
 };
 static double cost_per_entry_ms_defaults[] = {
 .015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
 };
 static double cost_per_byte_ms_defaults[] = {
 .00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
 };
 // these should be pretty consistent
 static double constant_other_time_ms_defaults[] = {
 .0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
 };
 static double young_other_cost_per_region_ms_defaults[] = {
 .3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
 };
 static double non_young_other_cost_per_region_ms_defaults[] = {
 .0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
 };
 // </NEW PREDICTION>
 G1CollectorPolicy::G1CollectorPolicy() :
   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
     ? ParallelGCThreads : 1),
   _n_pauses(0),
   _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _all_pause_times_ms(new NumberSeq()),
   _stop_world_start(0.0),
   _all_stop_world_times_ms(new NumberSeq()),
   _all_yield_times_ms(new NumberSeq()),
   _all_mod_union_times_ms(new NumberSeq()),
   _summary(new Summary()),
 #ifndef PRODUCT
   _cur_clear_ct_time_ms(0.0),
   _min_clear_cc_time_ms(-1.0),
   _max_clear_cc_time_ms(-1.0),
   _cur_clear_cc_time_ms(0.0),
   _cum_clear_cc_time_ms(0.0),
   _num_cc_clears(0L),
 #endif
   _region_num_young(0),
   _region_num_tenured(0),
   _prev_region_num_young(0),
   _prev_region_num_tenured(0),
   _aux_num(10),
   _all_aux_times_ms(new NumberSeq[_aux_num]),
   _cur_aux_start_times_ms(new double[_aux_num]),
   _cur_aux_times_ms(new double[_aux_num]),
   _cur_aux_times_set(new bool[_aux_num]),
   _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   // <NEW PREDICTION>
   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _prev_collection_pause_end_ms(0.0),
   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   _partially_young_cards_per_entry_ratio_seq(
                                          new TruncatedSeq(TruncatedSeqLength)),
   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   _non_young_other_cost_per_region_ms_seq(
                                          new TruncatedSeq(TruncatedSeqLength)),
   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   _pause_time_target_ms((double) MaxGCPauseMillis),
   // </NEW PREDICTION>
   _in_young_gc_mode(false),
   _full_young_gcs(true),
   _full_young_pause_num(0),
   _partial_young_pause_num(0),
   _during_marking(false),
   _in_marking_window(false),
   _in_marking_window_im(false),
   _known_garbage_ratio(0.0),
   _known_garbage_bytes(0),
   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
    _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
   _recent_avg_pause_time_ratio(0.0),
   _num_markings(0),
   _n_marks(0),
   _n_pauses_at_mark_end(0),
   _all_full_gc_times_ms(new NumberSeq()),
   // G1PausesBtwnConcMark defaults to -1
   // so the hack is to do the cast  QQQ FIXME
   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
   _n_marks_since_last_pause(0),
   _initiate_conc_mark_if_possible(false),
   _during_initial_mark_pause(false),
   _should_revert_to_full_young_gcs(false),
   _last_full_young_gc(false),
   _prev_collection_pause_used_at_end_bytes(0),
   _collection_set(NULL),
   _collection_set_size(0),
   _collection_set_bytes_used_before(0),
   // Incremental CSet attributes
   _inc_cset_build_state(Inactive),
   _inc_cset_head(NULL),
   _inc_cset_tail(NULL),
   _inc_cset_size(0),
   _inc_cset_young_index(0),
   _inc_cset_bytes_used_before(0),
   _inc_cset_max_finger(NULL),
   _inc_cset_recorded_young_bytes(0),
   _inc_cset_recorded_rs_lengths(0),
   _inc_cset_predicted_elapsed_time_ms(0.0),
   _inc_cset_predicted_bytes_to_copy(0),
 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 #endif // _MSC_VER
   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
                                                  G1YoungSurvRateNumRegionsSummary)),
   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
                                               G1YoungSurvRateNumRegionsSummary)),
   // add here any more surv rate groups
   _recorded_survivor_regions(0),
   _recorded_survivor_head(NULL),
   _recorded_survivor_tail(NULL),
   _survivors_age_table(true),
   _gc_overhead_perc(0.0)
 {
   // Set up the region size and associated fields. Given that the
   // policy is created before the heap, we have to set this up here,
   // so it's done as soon as possible.
   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   HeapRegionRemSet::setup_remset_size();
   // Verify PLAB sizes
   const uint region_size = HeapRegion::GrainWords;
   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
     char buffer[128];
     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
                  OldPLABSize > region_size ? "Old" : "Young", region_size);
     vm_exit_during_initialization(buffer);
   }
   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   _par_last_termination_attempts = new double[_parallel_gc_threads];
   _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
   // start conservatively
   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   // <NEW PREDICTION>
   int index;
   if (ParallelGCThreads == 0)
     index = 0;
   else if (ParallelGCThreads > 8)
     index = 7;
   else
     index = ParallelGCThreads - 1;
   _pending_card_diff_seq->add(0.0);
   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   _fully_young_cards_per_entry_ratio_seq->add(
                             fully_young_cards_per_entry_ratio_defaults[index]);
   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   _young_other_cost_per_region_ms_seq->add(
                                young_other_cost_per_region_ms_defaults[index]);
   _non_young_other_cost_per_region_ms_seq->add(
                            non_young_other_cost_per_region_ms_defaults[index]);
   // </NEW PREDICTION>
   // Below, we might need to calculate the pause time target based on
   // the pause interval. When we do so we are going to give G1 maximum
   // flexibility and allow it to do pauses when it needs to. So, we'll
   // arrange that the pause interval to be pause time target + 1 to
   // ensure that a) the pause time target is maximized with respect to
   // the pause interval and b) we maintain the invariant that pause
   // time target < pause interval. If the user does not want this
   // maximum flexibility, they will have to set the pause interval
   // explicitly.
   // First make sure that, if either parameter is set, its value is
   // reasonable.
   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
     if (MaxGCPauseMillis < 1) {
       vm_exit_during_initialization("MaxGCPauseMillis should be "
                                     "greater than 0");
     }
   }
   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
     if (GCPauseIntervalMillis < 1) {
       vm_exit_during_initialization("GCPauseIntervalMillis should be "
                                     "greater than 0");
     }
   }
   // Then, if the pause time target parameter was not set, set it to
   // the default value.
   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
       // The default pause time target in G1 is 200ms
       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
     } else {
       // We do not allow the pause interval to be set without the
       // pause time target
       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
                                     "without setting MaxGCPauseMillis");
     }
   }
   // Then, if the interval parameter was not set, set it according to
   // the pause time target (this will also deal with the case when the
   // pause time target is the default value).
   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
   }
   // Finally, make sure that the two parameters are consistent.
   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
     char buffer[256];
     jio_snprintf(buffer, 256,
                  "MaxGCPauseMillis (%u) should be less than "
                  "GCPauseIntervalMillis (%u)",
                  MaxGCPauseMillis, GCPauseIntervalMillis);
     vm_exit_during_initialization(buffer);
   }
   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   _sigma = (double) G1ConfidencePercent / 100.0;
   // start conservatively (around 50ms is about right)
   _concurrent_mark_init_times_ms->add(0.05);
   _concurrent_mark_remark_times_ms->add(0.05);
   _concurrent_mark_cleanup_times_ms->add(0.20);
   _tenuring_threshold = MaxTenuringThreshold;
   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   // fixed, then _max_survivor_regions will be calculated at
   // calculate_young_list_target_length during initialization
   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   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));
   initialize_all();
 }
 // Increment "i", mod "len"
 static void inc_mod(int& i, int len) {
   i++; if (i == len) i = 0;
 }
 void G1CollectorPolicy::initialize_flags() {
   set_min_alignment(HeapRegion::GrainBytes);
   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   if (SurvivorRatio < 1) {
     vm_exit_during_initialization("Invalid survivor ratio specified");
   }
   CollectorPolicy::initialize_flags();
 }
 // The easiest way to deal with the parsing of the NewSize /
 // MaxNewSize / etc. parameteres is to re-use the code in the
 // TwoGenerationCollectorPolicy class. This is similar to what
 // ParallelScavenge does with its GenerationSizer class (see
 // ParallelScavengeHeap::initialize()). We might change this in the
 // future, but it's a good start.
 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
   size_t size_to_region_num(size_t byte_size) {
     return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
   }
 public:
   G1YoungGenSizer() {
     initialize_flags();
     initialize_size_info();
   }
   size_t min_young_region_num() {
     return size_to_region_num(_min_gen0_size);
   }
   size_t initial_young_region_num() {
     return size_to_region_num(_initial_gen0_size);
   }
   size_t max_young_region_num() {
     return size_to_region_num(_max_gen0_size);
   }
 };
 void G1CollectorPolicy::init() {
   // Set aside an initial future to_space.
   _g1 = G1CollectedHeap::heap();
   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   initialize_gc_policy_counters();
   if (G1Gen) {
     _in_young_gc_mode = true;
     G1YoungGenSizer sizer;
     size_t initial_region_num = sizer.initial_young_region_num();
     if (UseAdaptiveSizePolicy) {
       set_adaptive_young_list_length(true);
       _young_list_fixed_length = 0;
     } else {
       set_adaptive_young_list_length(false);
       _young_list_fixed_length = initial_region_num;
     }
     _free_regions_at_end_of_collection = _g1->free_regions();
     calculate_young_list_min_length();
     guarantee( _young_list_min_length == 0, "invariant, not enough info" );
     calculate_young_list_target_length();
   } else {
      _young_list_fixed_length = 0;
     _in_young_gc_mode = false;
   }
   // 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, 2 + G1Gen);
 }
 void G1CollectorPolicy::calculate_young_list_min_length() {
   _young_list_min_length = 0;
   if (!adaptive_young_list_length())
     return;
   if (_alloc_rate_ms_seq->num() > 3) {
     double now_sec = os::elapsedTime();
     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
     double alloc_rate_ms = predict_alloc_rate_ms();
     size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
     size_t current_region_num = _g1->young_list()->length();
     _young_list_min_length = min_regions + current_region_num;
   }
 }
 void G1CollectorPolicy::calculate_young_list_target_length() {
   if (adaptive_young_list_length()) {
     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
     calculate_young_list_target_length(rs_lengths);
   } else {
     if (full_young_gcs())
       _young_list_target_length = _young_list_fixed_length;
     else
       _young_list_target_length = _young_list_fixed_length / 2;
   }
   // Make sure we allow the application to allocate at least one
   // region before we need to do a collection again.
   size_t min_length = _g1->young_list()->length() + 1;
   _young_list_target_length = MAX2(_young_list_target_length, min_length);
   calculate_max_gc_locker_expansion();
   calculate_survivors_policy();
 }
 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
   guarantee( adaptive_young_list_length(), "pre-condition" );
   guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
   double start_time_sec = os::elapsedTime();
   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   size_t reserve_regions =
     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
     // we are in fully-young mode and there are free regions in the heap
     double survivor_regions_evac_time =
         predict_survivor_regions_evac_time();
     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
     size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
                           + survivor_regions_evac_time;
     // the result
     size_t final_young_length = 0;
     size_t init_free_regions =
       MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
     // if we're still under the pause target...
     if (base_time_ms <= target_pause_time_ms) {
       // We make sure that the shortest young length that makes sense
       // fits within the target pause time.
       size_t min_young_length = 1;
       if (predict_will_fit(min_young_length, base_time_ms,
                                      init_free_regions, target_pause_time_ms)) {
         // The shortest young length will fit within 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
         size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
         size_t max_young_length = abs_max_young_length;
         if (max_young_length > min_young_length) {
           // Let's check if the initial max young length will fit within the
           // target pause. If so then there is no need to search for a maximal
           // young length - we'll return the initial maximum
           if (predict_will_fit(max_young_length, base_time_ms,
                                 init_free_regions, target_pause_time_ms)) {
             // The maximum young length will satisfy the target pause time.
             // We are done so set min young length to this maximum length.
             // The code after the loop will then set final_young_length using
             // the value cached in the minimum length.
             min_young_length = max_young_length;
           } else {
             // The maximum possible number of young regions will not fit within
             // the target pause time so let's search....
             size_t diff = (max_young_length - min_young_length) / 2;
             max_young_length = min_young_length + diff;
             while (max_young_length > min_young_length) {
               if (predict_will_fit(max_young_length, base_time_ms,
                                         init_free_regions, target_pause_time_ms)) {
                 // The current max young length will fit within the target
                 // pause time. Note we do not exit the loop here. By setting
                 // min = max, and then increasing the max below means that
                 // we will continue searching for an upper bound in the
                 // range [max..max+diff]
                 min_young_length = max_young_length;
               }
               diff = (max_young_length - min_young_length) / 2;
               max_young_length = min_young_length + diff;
             }
             // the above loop found a maximal young length that will fit
             // within the target pause time.
           }
           assert(min_young_length <= abs_max_young_length, "just checking");
         }
         final_young_length = min_young_length;
       }
     }
     // and we're done!
     // we should have at least one region in the target young length
     _young_list_target_length =
                               final_young_length + _recorded_survivor_regions;
     // let's keep an eye of how long we spend on this calculation
     // right now, I assume that we'll print it when we need it; we
     // should really adde it to the breakdown of a pause
     double end_time_sec = os::elapsedTime();
     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
 #ifdef TRACE_CALC_YOUNG_LENGTH
     // leave this in for debugging, just in case
     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
                            "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
                            target_pause_time_ms,
                            _young_list_target_length
                            elapsed_time_ms,
                            full_young_gcs() ? "full" : "partial",
                            during_initial_mark_pause() ? " i-m" : "",
                            _in_marking_window,
                            _in_marking_window_im);
 #endif // TRACE_CALC_YOUNG_LENGTH
     if (_young_list_target_length < _young_list_min_length) {
       // bummer; this means that, if we do a pause when the maximal
       // length dictates, we'll violate the pause spacing target (the
       // min length was calculate based on the application's current
       // alloc rate);
       // so, we have to bite the bullet, and allocate the minimum
       // number. We'll violate our target, but we just can't meet it.
 #ifdef TRACE_CALC_YOUNG_LENGTH
       // leave this in for debugging, just in case
       gclog_or_tty->print_cr("adjusted target length from "
                              SIZE_FORMAT " to " SIZE_FORMAT,
                              _young_list_target_length, _young_list_min_length);
 #endif // TRACE_CALC_YOUNG_LENGTH
       _young_list_target_length = _young_list_min_length;
     }
   } else {
     // we are in a partially-young mode or we've run out of regions (due
     // to evacuation failure)
 #ifdef TRACE_CALC_YOUNG_LENGTH
     // leave this in for debugging, just in case
     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
                            _young_list_min_length);
 #endif // TRACE_CALC_YOUNG_LENGTH
     // we'll do the pause as soon as possible by choosing the minimum
     _young_list_target_length = _young_list_min_length;
   }
   _rs_lengths_prediction = rs_lengths;
 }
 // This is used by: calculate_young_list_target_length(rs_length). It
 // returns true iff:
 //   the predicted pause time for the given young list will not overflow
 //   the target pause time
 // and:
 //   the predicted amount of surviving data will not overflow the
 //   the amount of free space available for survivor regions.
 //
 bool
 G1CollectorPolicy::predict_will_fit(size_t young_length,
                                     double base_time_ms,
                                     size_t init_free_regions,
                                     double target_pause_time_ms) {
   if (young_length >= init_free_regions)
     // end condition 1: not enough space for the young regions
     return false;
   double accum_surv_rate_adj = 0.0;
   double accum_surv_rate =
     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   size_t bytes_to_copy =
     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   double young_other_time_ms =
                        predict_young_other_time_ms(young_length);
   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: over the target pause time
     return false;
   size_t free_bytes =
                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
     // end condition 3: out of to-space (conservatively)
     return false;
   // success!
   return true;
 }
 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   double survivor_regions_evac_time = 0.0;
   for (HeapRegion * r = _recorded_survivor_head;
        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
        r = r->get_next_young_region()) {
     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   }
   return survivor_regions_evac_time;
 }
 void G1CollectorPolicy::check_prediction_validity() {
   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
   if (rs_lengths > _rs_lengths_prediction) {
     // add 10% to avoid having to recalculate often
     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
     calculate_young_list_target_length(rs_lengths_prediction);
   }
 }
 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
                                                bool is_tlab,
                                                bool* gc_overhead_limit_was_exceeded) {
   guarantee(false, "Not using this policy feature yet.");
   return NULL;
 }
 // This method controls how a collector handles one or more
 // of its generations being fully allocated.
 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
                                                        bool is_tlab) {
   guarantee(false, "Not using this policy feature yet.");
   return NULL;
 }
 #ifndef PRODUCT
 bool G1CollectorPolicy::verify_young_ages() {
   HeapRegion* head = _g1->young_list()->first_region();
   return
     verify_young_ages(head, _short_lived_surv_rate_group);
   // also call verify_young_ages on any additional surv rate groups
 }
 bool
 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
                                      SurvRateGroup *surv_rate_group) {
   guarantee( surv_rate_group != NULL, "pre-condition" );
   const char* name = surv_rate_group->name();
   bool ret = true;
   int prev_age = -1;
   for (HeapRegion* curr = head;
        curr != NULL;
        curr = curr->get_next_young_region()) {
     SurvRateGroup* group = curr->surv_rate_group();
     if (group == NULL && !curr->is_survivor()) {
       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
       ret = false;
     }
     if (surv_rate_group == group) {
       int age = curr->age_in_surv_rate_group();
       if (age < 0) {
         gclog_or_tty->print_cr("## %s: encountered negative age", name);
         ret = false;
       }
       if (age <= prev_age) {
         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
                                "(%d, %d)", name, age, prev_age);
         ret = false;
       }
       prev_age = age;
     }
   }
   return ret;
 }
 #endif // PRODUCT
 void G1CollectorPolicy::record_full_collection_start() {
   _cur_collection_start_sec = os::elapsedTime();
   // Release the future to-space so that it is available for compaction into.
   _g1->set_full_collection();
 }
 void G1CollectorPolicy::record_full_collection_end() {
   // Consider this like a collection pause for the purposes of allocation
   // since last pause.
   double end_sec = os::elapsedTime();
   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
   double full_gc_time_ms = full_gc_time_sec * 1000.0;
   _all_full_gc_times_ms->add(full_gc_time_ms);
   update_recent_gc_times(end_sec, full_gc_time_ms);
   _g1->clear_full_collection();
   // "Nuke" the heuristics that control the fully/partially young GC
   // transitions and make sure we start with fully young GCs after the
   // Full GC.
   set_full_young_gcs(true);
   _last_full_young_gc = false;
   _should_revert_to_full_young_gcs = false;
   clear_initiate_conc_mark_if_possible();
   clear_during_initial_mark_pause();
   _known_garbage_bytes = 0;
   _known_garbage_ratio = 0.0;
   _in_marking_window = false;
   _in_marking_window_im = false;
   _short_lived_surv_rate_group->start_adding_regions();
   // also call this on any additional surv rate groups
   record_survivor_regions(0, NULL, NULL);
   _prev_region_num_young   = _region_num_young;
   _prev_region_num_tenured = _region_num_tenured;
   _free_regions_at_end_of_collection = _g1->free_regions();
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   calculate_young_list_min_length();
   calculate_young_list_target_length();
 }
 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
   _bytes_in_to_space_before_gc += bytes;
 }
 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
   _bytes_in_to_space_after_gc += bytes;
 }
 void G1CollectorPolicy::record_stop_world_start() {
   _stop_world_start = os::elapsedTime();
 }
 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
                                                       size_t start_used) {
   if (PrintGCDetails) {
     gclog_or_tty->stamp(PrintGCTimeStamps);
     gclog_or_tty->print("[GC pause");
     if (in_young_gc_mode())
       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
   }
   assert(_g1->used() == _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_to_space_before_gc = 0;
   _bytes_in_to_space_after_gc = 0;
   _bytes_in_collection_set_before_gc = 0;
 #ifdef DEBUG
   // initialise these to something well known so that we can spot
   // if they are not set properly
   for (int i = 0; i < _parallel_gc_threads; ++i) {
     _par_last_gc_worker_start_times_ms[i] = -1234.0;
     _par_last_ext_root_scan_times_ms[i] = -1234.0;
     _par_last_mark_stack_scan_times_ms[i] = -1234.0;
     _par_last_update_rs_times_ms[i] = -1234.0;
     _par_last_update_rs_processed_buffers[i] = -1234.0;
     _par_last_scan_rs_times_ms[i] = -1234.0;
     _par_last_obj_copy_times_ms[i] = -1234.0;
     _par_last_termination_times_ms[i] = -1234.0;
     _par_last_termination_attempts[i] = -1234.0;
     _par_last_gc_worker_end_times_ms[i] = -1234.0;
   }
 #endif
   for (int i = 0; i < _aux_num; ++i) {
     _cur_aux_times_ms[i] = 0.0;
     _cur_aux_times_set[i] = false;
   }
   _satb_drain_time_set = false;
   _last_satb_drain_processed_buffers = -1;
   if (in_young_gc_mode())
     _last_young_gc_full = false;
   // do that for any other surv rate groups
   _short_lived_surv_rate_group->stop_adding_regions();
   _survivors_age_table.clear();
   assert( verify_young_ages(), "region age verification" );
 }
 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
   _mark_closure_time_ms = mark_closure_time_ms;
 }
 void G1CollectorPolicy::record_concurrent_mark_init_start() {
   _mark_init_start_sec = os::elapsedTime();
   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
 }
 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
                                                    mark_init_elapsed_time_ms) {
   _during_marking = true;
   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_init_end() {
   double end_time_sec = os::elapsedTime();
   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
   record_concurrent_mark_init_end_pre(elapsed_time_ms);
   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
 }
 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
   _mark_remark_start_sec = os::elapsedTime();
   _during_marking = false;
 }
 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
   double end_time_sec = os::elapsedTime();
   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   _prev_collection_pause_end_ms += elapsed_time_ms;
   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
 }
 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
   _mark_cleanup_start_sec = os::elapsedTime();
 }
 void
 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
                                                       size_t max_live_bytes) {
   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
   record_concurrent_mark_cleanup_end_work2();
 }
 void
 G1CollectorPolicy::
 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
                                          size_t max_live_bytes) {
   if (_n_marks < 2) _n_marks++;
   if (G1PolicyVerbose > 0)
     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
                            " (of " SIZE_FORMAT " MB heap).",
                            max_live_bytes/M, _g1->capacity()/M);
 }
 // The important thing about this is that it includes "os::elapsedTime".
 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
   double end_time_sec = os::elapsedTime();
   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   _prev_collection_pause_end_ms += elapsed_time_ms;
   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
   _num_markings++;
   // We did a marking, so reset the "since_last_mark" variables.
   double considerConcMarkCost = 1.0;
   // If there are available processors, concurrent activity is free...
   if (Threads::number_of_non_daemon_threads() * 2 <
       os::active_processor_count()) {
     considerConcMarkCost = 0.0;
   }
   _n_pauses_at_mark_end = _n_pauses;
   _n_marks_since_last_pause++;
 }
 void
 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
   if (in_young_gc_mode()) {
     _should_revert_to_full_young_gcs = false;
     _last_full_young_gc = true;
     _in_marking_window = false;
     if (adaptive_young_list_length())
       calculate_young_list_target_length();
   }
 }
 void G1CollectorPolicy::record_concurrent_pause() {
   if (_stop_world_start > 0.0) {
     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
     _all_yield_times_ms->add(yield_ms);
   }
 }
 void G1CollectorPolicy::record_concurrent_pause_end() {
 }
 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
   _cur_CH_strong_roots_end_sec = os::elapsedTime();
   _cur_CH_strong_roots_dur_ms =
     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
 }
 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
   _cur_G1_strong_roots_end_sec = os::elapsedTime();
   _cur_G1_strong_roots_dur_ms =
     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
 }
 template<class T>
 T sum_of(T* sum_arr, int start, int n, int N) {
   T sum = (T)0;
   for (int i = 0; i < n; i++) {
     int j = (start + i) % N;
     sum += sum_arr[j];
   }
   return sum;
 }
 void G1CollectorPolicy::print_par_stats(int level,
                                         const char* str,
                                         double* data,
                                          bool summary) {
   double min = data[0], max = data[0];
   double total = 0.0;
   int j;
   for (j = 0; j < level; ++j)
     gclog_or_tty->print("   ");
   gclog_or_tty->print("[%s (ms):", str);
   for (uint i = 0; i < ParallelGCThreads; ++i) {
     double val = data[i];
     if (val < min)
       min = val;
     if (val > max)
       max = val;
     total += val;
     gclog_or_tty->print("  %3.1lf", val);
   }
   if (summary) {
     gclog_or_tty->print_cr("");
     double avg = total / (double) ParallelGCThreads;
     gclog_or_tty->print(" ");
     for (j = 0; j < level; ++j)
       gclog_or_tty->print("   ");
     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
                         avg, min, max);
   }
   gclog_or_tty->print_cr("]");
 }
 void G1CollectorPolicy::print_par_sizes(int level,
                                         const char* str,
                                         double* data,
                                         bool summary) {
   double min = data[0], max = data[0];
   double total = 0.0;
   int j;
   for (j = 0; j < level; ++j)
     gclog_or_tty->print("   ");
   gclog_or_tty->print("[%s :", str);
   for (uint i = 0; i < ParallelGCThreads; ++i) {
     double val = data[i];
     if (val < min)
       min = val;
     if (val > max)
       max = val;
     total += val;
     gclog_or_tty->print(" %d", (int) val);
   }
   if (summary) {
     gclog_or_tty->print_cr("");
     double avg = total / (double) ParallelGCThreads;
     gclog_or_tty->print(" ");
     for (j = 0; j < level; ++j)
       gclog_or_tty->print("   ");
     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
                (int)total, (int)avg, (int)min, (int)max);
   }
   gclog_or_tty->print_cr("]");
 }
 void G1CollectorPolicy::print_stats (int level,
                                      const char* str,
                                      double value) {
   for (int j = 0; j < level; ++j)
     gclog_or_tty->print("   ");
   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
 }
 void G1CollectorPolicy::print_stats (int level,
                                      const char* str,
                                      int value) {
   for (int j = 0; j < level; ++j)
     gclog_or_tty->print("   ");
   gclog_or_tty->print_cr("[%s: %d]", str, value);
 }
 double G1CollectorPolicy::avg_value (double* data) {
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     double ret = 0.0;
     for (uint i = 0; i < ParallelGCThreads; ++i)
       ret += data[i];
     return ret / (double) ParallelGCThreads;
   } else {
     return data[0];
   }
 }
 double G1CollectorPolicy::max_value (double* data) {
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     double ret = data[0];
     for (uint i = 1; i < ParallelGCThreads; ++i)
       if (data[i] > ret)
         ret = data[i];
     return ret;
   } else {
     return data[0];
   }
 }
 double G1CollectorPolicy::sum_of_values (double* data) {
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     double sum = 0.0;
     for (uint i = 0; i < ParallelGCThreads; i++)
       sum += data[i];
     return sum;
   } else {
     return data[0];
   }
 }
 double G1CollectorPolicy::max_sum (double* data1,
                                    double* data2) {
   double ret = data1[0] + data2[0];
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     for (uint i = 1; i < ParallelGCThreads; ++i) {
       double data = data1[i] + data2[i];
       if (data > ret)
         ret = data;
     }
   }
   return ret;
 }
 // Anything below that is considered to be zero
 #define MIN_TIMER_GRANULARITY 0.0000001
 void G1CollectorPolicy::record_collection_pause_end() {
   double end_time_sec = os::elapsedTime();
   double elapsed_ms = _last_pause_time_ms;
   bool parallel = G1CollectedHeap::use_parallel_gc_threads();
   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
   size_t rs_size =
     _cur_collection_pause_used_regions_at_start - collection_set_size();
   size_t cur_used_bytes = _g1->used();
   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
   bool last_pause_included_initial_mark = false;
   bool update_stats = !_g1->evacuation_failed();
 #ifndef PRODUCT
   if (G1YoungSurvRateVerbose) {
     gclog_or_tty->print_cr("");
     _short_lived_surv_rate_group->print();
     // do that for any other surv rate groups too
   }
 #endif // PRODUCT
   if (in_young_gc_mode()) {
     last_pause_included_initial_mark = during_initial_mark_pause();
     if (last_pause_included_initial_mark)
       record_concurrent_mark_init_end_pre(0.0);
     size_t min_used_targ =
       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
     if (!_g1->mark_in_progress() && !_last_full_young_gc) {
       assert(!last_pause_included_initial_mark, "invariant");
       if (cur_used_bytes > min_used_targ &&
           cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
         assert(!during_initial_mark_pause(), "we should not see this here");
         // 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();
       }
     }
     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
   }
   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
                           end_time_sec, false);
   guarantee(_cur_collection_pause_used_regions_at_start >=
             collection_set_size(),
             "Negative RS size?");
   // This assert is exempted when we're doing parallel collection pauses,
   // because the fragmentation caused by the parallel GC allocation buffers
   // can lead to more memory being used during collection than was used
   // before. Best leave this out until the fragmentation problem is fixed.
   // Pauses in which evacuation failed can also lead to negative
   // collections, since no space is reclaimed from a region containing an
   // object whose evacuation failed.
   // Further, we're now always doing parallel collection.  But I'm still
   // leaving this here as a placeholder for a more precise assertion later.
   // (DLD, 10/05.)
   assert((true || parallel) // Always using GC LABs now.
          || _g1->evacuation_failed()
          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
          "Negative collection");
   size_t freed_bytes =
     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
   double survival_fraction =
     (double)surviving_bytes/
     (double)_collection_set_bytes_used_before;
   _n_pauses++;
   if (update_stats) {
     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
     _recent_evac_times_ms->add(evac_ms);
     _recent_pause_times_ms->add(elapsed_ms);
     _recent_rs_sizes->add(rs_size);
     // We exempt parallel collection from this check because Alloc Buffer
     // fragmentation can produce negative collections.  Same with evac
     // failure.
     // Further, we're now always doing parallel collection.  But I'm still
     // leaving this here as a placeholder for a more precise assertion later.
     // (DLD, 10/05.
     assert((true || parallel)
            || _g1->evacuation_failed()
            || surviving_bytes <= _collection_set_bytes_used_before,
            "Or else negative collection!");
     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
     _recent_CS_bytes_surviving->add(surviving_bytes);
     // this is where we update the allocation rate of the application
     double app_time_ms =
       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
     if (app_time_ms < MIN_TIMER_GRANULARITY) {
       // This usually happens due to the timer not having the required
       // granularity. Some Linuxes are the usual culprits.
       // We'll just set it to something (arbitrarily) small.
       app_time_ms = 1.0;
     }
     size_t regions_allocated =
       (_region_num_young - _prev_region_num_young) +
       (_region_num_tenured - _prev_region_num_tenured);
     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
     _alloc_rate_ms_seq->add(alloc_rate_ms);
     _prev_region_num_young   = _region_num_young;
     _prev_region_num_tenured = _region_num_tenured;
     double interval_ms =
       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
     update_recent_gc_times(end_time_sec, elapsed_ms);
     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
     if (recent_avg_pause_time_ratio() < 0.0 ||
         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
 #ifndef PRODUCT
       // Dump info to allow post-facto debugging
       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
       gclog_or_tty->print_cr("-------------------------------------------");
       gclog_or_tty->print_cr("Recent GC Times (ms):");
       _recent_gc_times_ms->dump();
       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
       _recent_prev_end_times_for_all_gcs_sec->dump();
       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
       // In debug mode, terminate the JVM if the user wants to debug at this point.
       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
 #endif  // !PRODUCT
       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
       if (_recent_avg_pause_time_ratio < 0.0) {
         _recent_avg_pause_time_ratio = 0.0;
       } else {
         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
         _recent_avg_pause_time_ratio = 1.0;
       }
     }
   }
   if (G1PolicyVerbose > 1) {
     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
   }
   PauseSummary* summary = _summary;
   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
   double update_rs_processed_buffers =
     sum_of_values(_par_last_update_rs_processed_buffers);
   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
   double termination_time = avg_value(_par_last_termination_times_ms);
   double parallel_other_time = _cur_collection_par_time_ms -
     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
      scan_rs_time + obj_copy_time + termination_time);
   if (update_stats) {
     MainBodySummary* body_summary = summary->main_body_summary();
     guarantee(body_summary != NULL, "should not be null!");
     if (_satb_drain_time_set)
       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
     else
       body_summary->record_satb_drain_time_ms(0.0);
     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
     body_summary->record_update_rs_time_ms(update_rs_time);
     body_summary->record_scan_rs_time_ms(scan_rs_time);
     body_summary->record_obj_copy_time_ms(obj_copy_time);
     if (parallel) {
       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
       body_summary->record_termination_time_ms(termination_time);
       body_summary->record_parallel_other_time_ms(parallel_other_time);
     }
     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
   }
   if (G1PolicyVerbose > 1) {
     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"
                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"
                            "        Evac:      %10.6f ms    (avg: %10.6f ms)\n"
                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
                            "      |RS|: " SIZE_FORMAT,
                            elapsed_ms, recent_avg_time_for_pauses_ms(),
                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
                            evac_ms, recent_avg_time_for_evac_ms(),
                            scan_rs_time,
                            recent_avg_time_for_pauses_ms() -
                            recent_avg_time_for_G1_strong_ms(),
                            rs_size);
     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
                            "       At end " SIZE_FORMAT "K\n"
                            "       garbage      : " SIZE_FORMAT "K"
                            "       of     " SIZE_FORMAT "K\n"
                            "       survival     : %6.2f%%  (%6.2f%% avg)",
                            _cur_collection_pause_used_at_start_bytes/K,
                            _g1->used()/K, freed_bytes/K,
                            _collection_set_bytes_used_before/K,
                            survival_fraction*100.0,
                            recent_avg_survival_fraction()*100.0);
     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
                            recent_avg_pause_time_ratio() * 100.0);
   }
   double other_time_ms = elapsed_ms;
   if (_satb_drain_time_set) {
     other_time_ms -= _cur_satb_drain_time_ms;
   }
   if (parallel) {
     other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
   } else {
     other_time_ms -=
       update_rs_time +
       ext_root_scan_time + mark_stack_scan_time +
       scan_rs_time + obj_copy_time;
   }
   if (PrintGCDetails) {
     gclog_or_tty->print_cr("%s, %1.8lf secs]",
                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
                            elapsed_ms / 1000.0);
     if (_satb_drain_time_set) {
       print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
     }
     if (_last_satb_drain_processed_buffers >= 0) {
       print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
     }
     if (parallel) {
       print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
       print_par_stats(2, "GC Worker Start Time",
                       _par_last_gc_worker_start_times_ms, false);
       print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
       print_par_sizes(3, "Processed Buffers",
                       _par_last_update_rs_processed_buffers, true);
       print_par_stats(2, "Ext Root Scanning",
                       _par_last_ext_root_scan_times_ms);
       print_par_stats(2, "Mark Stack Scanning",
                       _par_last_mark_stack_scan_times_ms);
       print_par_stats(2, "Scan 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, true);
       print_par_stats(2, "GC Worker End Time",
                       _par_last_gc_worker_end_times_ms, false);
       print_stats(2, "Other", parallel_other_time);
       print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
     } else {
       print_stats(1, "Update RS", update_rs_time);
       print_stats(2, "Processed Buffers",
                   (int)update_rs_processed_buffers);
       print_stats(1, "Ext Root Scanning", ext_root_scan_time);
       print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
       print_stats(1, "Scan RS", scan_rs_time);
       print_stats(1, "Object Copying", obj_copy_time);
     }
 #ifndef PRODUCT
     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
     if (_num_cc_clears > 0) {
       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
     }
 #endif
     print_stats(1, "Other", other_time_ms);
     print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
     for (int i = 0; i < _aux_num; ++i) {
       if (_cur_aux_times_set[i]) {
         char buffer[96];
         sprintf(buffer, "Aux%d", i);
         print_stats(1, buffer, _cur_aux_times_ms[i]);
       }
     }
   }
   if (PrintGCDetails)
     gclog_or_tty->print("   [");
   if (PrintGC || PrintGCDetails)
     _g1->print_size_transition(gclog_or_tty,
                                _cur_collection_pause_used_at_start_bytes,
                                _g1->used(), _g1->capacity());
   if (PrintGCDetails)
     gclog_or_tty->print_cr("]");
   _all_pause_times_ms->add(elapsed_ms);
   if (update_stats) {
     summary->record_total_time_ms(elapsed_ms);
     summary->record_other_time_ms(other_time_ms);
   }
   for (int i = 0; i < _aux_num; ++i)
     if (_cur_aux_times_set[i])
       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
   // Reset marks-between-pauses counter.
   _n_marks_since_last_pause = 0;
   // Update the efficiency-since-mark vars.
   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
     // This usually happens due to the timer not having the required
     // granularity. Some Linuxes are the usual culprits.
     // We'll just set it to something (arbitrarily) small.
     proc_ms = 1.0;
   }
   double cur_efficiency = (double) freed_bytes / proc_ms;
   bool new_in_marking_window = _in_marking_window;
   bool new_in_marking_window_im = false;
   if (during_initial_mark_pause()) {
     new_in_marking_window = true;
     new_in_marking_window_im = true;
   }
   if (in_young_gc_mode()) {
     if (_last_full_young_gc) {
       set_full_young_gcs(false);
       _last_full_young_gc = false;
     }
     if ( !_last_young_gc_full ) {
       if ( _should_revert_to_full_young_gcs ||
            _known_garbage_ratio < 0.05 ||
            (adaptive_young_list_length() &&
            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
         set_full_young_gcs(true);
       }
     }
     _should_revert_to_full_young_gcs = false;
     if (_last_young_gc_full && !_during_marking)
       _young_gc_eff_seq->add(cur_efficiency);
   }
   _short_lived_surv_rate_group->start_adding_regions();
   // do that for any other surv rate groupsx
   // <NEW PREDICTION>
   if (update_stats) {
     double pause_time_ms = elapsed_ms;
     size_t diff = 0;
     if (_max_pending_cards >= _pending_cards)
       diff = _max_pending_cards - _pending_cards;
     _pending_card_diff_seq->add((double) diff);
     double cost_per_card_ms = 0.0;
     if (_pending_cards > 0) {
       cost_per_card_ms = update_rs_time / (double) _pending_cards;
       _cost_per_card_ms_seq->add(cost_per_card_ms);
     }
     size_t cards_scanned = _g1->cards_scanned();
     double cost_per_entry_ms = 0.0;
     if (cards_scanned > 10) {
       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
       if (_last_young_gc_full)
         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
       else
         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
     }
     if (_max_rs_lengths > 0) {
       double cards_per_entry_ratio =
         (double) cards_scanned / (double) _max_rs_lengths;
       if (_last_young_gc_full)
         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
       else
         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
     }
     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
     if (rs_length_diff >= 0)
       _rs_length_diff_seq->add((double) rs_length_diff);
     size_t copied_bytes = surviving_bytes;
     double cost_per_byte_ms = 0.0;
     if (copied_bytes > 0) {
       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
       if (_in_marking_window)
         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
       else
         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
     }
     double all_other_time_ms = pause_time_ms -
       (update_rs_time + scan_rs_time + obj_copy_time +
        _mark_closure_time_ms + termination_time);
     double young_other_time_ms = 0.0;
     if (_recorded_young_regions > 0) {
       young_other_time_ms =
         _recorded_young_cset_choice_time_ms +
         _recorded_young_free_cset_time_ms;
       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
                                              (double) _recorded_young_regions);
     }
     double non_young_other_time_ms = 0.0;
     if (_recorded_non_young_regions > 0) {
       non_young_other_time_ms =
         _recorded_non_young_cset_choice_time_ms +
         _recorded_non_young_free_cset_time_ms;
       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
                                          (double) _recorded_non_young_regions);
     }
     double constant_other_time_ms = all_other_time_ms -
       (young_other_time_ms + non_young_other_time_ms);
     _constant_other_time_ms_seq->add(constant_other_time_ms);
     double survival_ratio = 0.0;
     if (_bytes_in_collection_set_before_gc > 0) {
       survival_ratio = (double) bytes_in_to_space_during_gc() /
         (double) _bytes_in_collection_set_before_gc;
     }
     _pending_cards_seq->add((double) _pending_cards);
     _scanned_cards_seq->add((double) cards_scanned);
     _rs_lengths_seq->add((double) _max_rs_lengths);
     double expensive_region_limit_ms =
       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
     if (expensive_region_limit_ms < 0.0) {
       // this means that the other time was predicted to be longer than
       // than the max pause time
       expensive_region_limit_ms = (double) MaxGCPauseMillis;
     }
     _expensive_region_limit_ms = expensive_region_limit_ms;
     if (PREDICTIONS_VERBOSE) {
       gclog_or_tty->print_cr("");
       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
                     "REGIONS %d %d %d "
                     "PENDING_CARDS %d %d "
                     "CARDS_SCANNED %d %d "
                     "RS_LENGTHS %d %d "
                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
                     "SURVIVAL_RATIO %1.6lf %1.6lf "
                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
                     "OTHER_YOUNG %1.6lf %1.6lf "
                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
                     "ELAPSED %1.6lf %1.6lf ",
                     _cur_collection_start_sec,
                     (!_last_young_gc_full) ? 2 :
                     (last_pause_included_initial_mark) ? 1 : 0,
                     _recorded_region_num,
                     _recorded_young_regions,
                     _recorded_non_young_regions,
                     _predicted_pending_cards, _pending_cards,
                     _predicted_cards_scanned, cards_scanned,
                     _predicted_rs_lengths, _max_rs_lengths,
                     _predicted_rs_update_time_ms, update_rs_time,
                     _predicted_rs_scan_time_ms, scan_rs_time,
                     _predicted_survival_ratio, survival_ratio,
                     _predicted_object_copy_time_ms, obj_copy_time,
                     _predicted_constant_other_time_ms, constant_other_time_ms,
                     _predicted_young_other_time_ms, young_other_time_ms,
                     _predicted_non_young_other_time_ms,
                     non_young_other_time_ms,
                     _vtime_diff_ms, termination_time,
                     _predicted_pause_time_ms, elapsed_ms);
     }
     if (G1PolicyVerbose > 0) {
       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
                     _predicted_pause_time_ms,
                     (_within_target) ? "within" : "outside",
                     elapsed_ms);
     }
   }
   _in_marking_window = new_in_marking_window;
   _in_marking_window_im = new_in_marking_window_im;
   _free_regions_at_end_of_collection = _g1->free_regions();
   calculate_young_list_min_length();
   calculate_young_list_target_length();
   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
   // </NEW PREDICTION>
 }
 // <NEW PREDICTION>
 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
                                                      double update_rs_processed_buffers,
                                                      double goal_ms) {
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
   if (G1UseAdaptiveConcRefinement) {
     const int k_gy = 3, k_gr = 6;
     const double inc_k = 1.1, dec_k = 0.9;
     int g = cg1r->green_zone();
     if (update_rs_time > goal_ms) {
       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
     } else {
       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
         g = (int)MAX2(g * inc_k, g + 1.0);
       }
     }
     // Change the refinement threads params
     cg1r->set_green_zone(g);
     cg1r->set_yellow_zone(g * k_gy);
     cg1r->set_red_zone(g * k_gr);
     cg1r->reinitialize_threads();
     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
                                     cg1r->yellow_zone());
     // Change the barrier params
     dcqs.set_process_completed_threshold(processing_threshold);
     dcqs.set_max_completed_queue(cg1r->red_zone());
   }
   int curr_queue_size = dcqs.completed_buffers_num();
   if (curr_queue_size >= cg1r->yellow_zone()) {
     dcqs.set_completed_queue_padding(curr_queue_size);
   } else {
     dcqs.set_completed_queue_padding(0);
   }
   dcqs.notify_if_necessary();
 }
 double
 G1CollectorPolicy::
 predict_young_collection_elapsed_time_ms(size_t adjustment) {
   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   size_t young_num = g1h->young_list()->length();
   if (young_num == 0)
     return 0.0;
   young_num += adjustment;
   size_t pending_cards = predict_pending_cards();
   size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
                       predict_rs_length_diff();
   size_t card_num;
   if (full_young_gcs())
     card_num = predict_young_card_num(rs_lengths);
   else
     card_num = predict_non_young_card_num(rs_lengths);
   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
   double accum_yg_surv_rate =
     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
   size_t bytes_to_copy =
     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
   return
     predict_rs_update_time_ms(pending_cards) +
     predict_rs_scan_time_ms(card_num) +
     predict_object_copy_time_ms(bytes_to_copy) +
     predict_young_other_time_ms(young_num) +
     predict_constant_other_time_ms();
 }
 double
 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
   size_t rs_length = predict_rs_length_diff();
   size_t card_num;
   if (full_young_gcs())
     card_num = predict_young_card_num(rs_length);
   else
     card_num = predict_non_young_card_num(rs_length);
   return predict_base_elapsed_time_ms(pending_cards, card_num);
 }
 double
 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
                                                 size_t scanned_cards) {
   return
     predict_rs_update_time_ms(pending_cards) +
     predict_rs_scan_time_ms(scanned_cards) +
     predict_constant_other_time_ms();
 }
 double
 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
                                                   bool young) {
   size_t rs_length = hr->rem_set()->occupied();
   size_t card_num;
   if (full_young_gcs())
     card_num = predict_young_card_num(rs_length);
   else
     card_num = predict_non_young_card_num(rs_length);
   size_t bytes_to_copy = predict_bytes_to_copy(hr);
   double region_elapsed_time_ms =
     predict_rs_scan_time_ms(card_num) +
     predict_object_copy_time_ms(bytes_to_copy);
   if (young)
     region_elapsed_time_ms += predict_young_other_time_ms(1);
   else
     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
   return region_elapsed_time_ms;
 }
 size_t
 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
   size_t bytes_to_copy;
   if (hr->is_marked())
     bytes_to_copy = hr->max_live_bytes();
   else {
     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
                "invariant" );
     int age = hr->age_in_surv_rate_group();
     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
   }
   return bytes_to_copy;
 }
 void
 G1CollectorPolicy::start_recording_regions() {
   _recorded_rs_lengths            = 0;
   _recorded_young_regions         = 0;
   _recorded_non_young_regions     = 0;
 #if PREDICTIONS_VERBOSE
   _recorded_marked_bytes          = 0;
   _recorded_young_bytes           = 0;
   _predicted_bytes_to_copy        = 0;
   _predicted_rs_lengths           = 0;
   _predicted_cards_scanned        = 0;
 #endif // PREDICTIONS_VERBOSE
 }
 void
 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
 #if PREDICTIONS_VERBOSE
   if (!young) {
     _recorded_marked_bytes += hr->max_live_bytes();
   }
   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
 #endif // PREDICTIONS_VERBOSE
   size_t rs_length = hr->rem_set()->occupied();
   _recorded_rs_lengths += rs_length;
 }
 void
 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
   assert(!hr->is_young(), "should not call this");
   ++_recorded_non_young_regions;
   record_cset_region_info(hr, false);
 }
 void
 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
   _recorded_young_regions = n_regions;
 }
 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
 #if PREDICTIONS_VERBOSE
   _recorded_young_bytes = bytes;
 #endif // PREDICTIONS_VERBOSE
 }
 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
   _recorded_rs_lengths = rs_lengths;
 }
 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
   _predicted_bytes_to_copy = bytes;
 }
 void
 G1CollectorPolicy::end_recording_regions() {
   // The _predicted_pause_time_ms field is referenced in code
   // not under PREDICTIONS_VERBOSE. Let's initialize it.
   _predicted_pause_time_ms = -1.0;
 #if PREDICTIONS_VERBOSE
   _predicted_pending_cards = predict_pending_cards();
   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
   if (full_young_gcs())
     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
   else
     _predicted_cards_scanned +=
       predict_non_young_card_num(_predicted_rs_lengths);
   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
   _predicted_rs_update_time_ms =
     predict_rs_update_time_ms(_g1->pending_card_num());
   _predicted_rs_scan_time_ms =
     predict_rs_scan_time_ms(_predicted_cards_scanned);
   _predicted_object_copy_time_ms =
     predict_object_copy_time_ms(_predicted_bytes_to_copy);
   _predicted_constant_other_time_ms =
     predict_constant_other_time_ms();
   _predicted_young_other_time_ms =
     predict_young_other_time_ms(_recorded_young_regions);
   _predicted_non_young_other_time_ms =
     predict_non_young_other_time_ms(_recorded_non_young_regions);
   _predicted_pause_time_ms =
     _predicted_rs_update_time_ms +
     _predicted_rs_scan_time_ms +
     _predicted_object_copy_time_ms +
     _predicted_constant_other_time_ms +
     _predicted_young_other_time_ms +
     _predicted_non_young_other_time_ms;
 #endif // PREDICTIONS_VERBOSE
 }
 void G1CollectorPolicy::check_if_region_is_too_expensive(double
                                                            predicted_time_ms) {
   // I don't think we need to do this when in young GC mode since
   // marking will be initiated next time we hit the soft limit anyway...
   if (predicted_time_ms > _expensive_region_limit_ms) {
     if (!in_young_gc_mode()) {
         set_full_young_gcs(true);
         // We might want to do something different here. However,
         // right now we don't support the non-generational G1 mode
         // (and in fact we are planning to remove the associated code,
         // see CR 6814390). So, let's leave it as is and this will be
         // removed some time in the future
         ShouldNotReachHere();
         set_during_initial_mark_pause();
     } else
       // no point in doing another partial one
       _should_revert_to_full_young_gcs = true;
   }
 }
 // </NEW PREDICTION>
 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
                                                double elapsed_ms) {
   _recent_gc_times_ms->add(elapsed_ms);
   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
 }
 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
   if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
   else return _recent_pause_times_ms->avg();
 }
 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
   if (_recent_CH_strong_roots_times_ms->num() == 0)
     return (double)MaxGCPauseMillis/3.0;
   else return _recent_CH_strong_roots_times_ms->avg();
 }
 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
   if (_recent_G1_strong_roots_times_ms->num() == 0)
     return (double)MaxGCPauseMillis/3.0;
   else return _recent_G1_strong_roots_times_ms->avg();
 }
 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
   else return _recent_evac_times_ms->avg();
 }
 int G1CollectorPolicy::number_of_recent_gcs() {
   assert(_recent_CH_strong_roots_times_ms->num() ==
          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
   assert(_recent_G1_strong_roots_times_ms->num() ==
          _recent_evac_times_ms->num(), "Sequence out of sync");
   assert(_recent_evac_times_ms->num() ==
          _recent_pause_times_ms->num(), "Sequence out of sync");
   assert(_recent_pause_times_ms->num() ==
          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
   assert(_recent_CS_bytes_used_before->num() ==
          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
   return _recent_pause_times_ms->num();
 }
 double G1CollectorPolicy::recent_avg_survival_fraction() {
   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
                                            _recent_CS_bytes_used_before);
 }
 double G1CollectorPolicy::last_survival_fraction() {
   return last_survival_fraction_work(_recent_CS_bytes_surviving,
                                      _recent_CS_bytes_used_before);
 }
 double
 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
                                                      TruncatedSeq* before) {
   assert(surviving->num() == before->num(), "Sequence out of sync");
   if (before->sum() > 0.0) {
       double recent_survival_rate = surviving->sum() / before->sum();
       // We exempt parallel collection from this check because Alloc Buffer
       // fragmentation can produce negative collections.
       // Further, we're now always doing parallel collection.  But I'm still
       // leaving this here as a placeholder for a more precise assertion later.
       // (DLD, 10/05.)
       assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
              _g1->evacuation_failed() ||
              recent_survival_rate <= 1.0, "Or bad frac");
       return recent_survival_rate;
   } else {
     return 1.0; // Be conservative.
   }
 }
 double
 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
                                                TruncatedSeq* before) {
   assert(surviving->num() == before->num(), "Sequence out of sync");
   if (surviving->num() > 0 && before->last() > 0.0) {
     double last_survival_rate = surviving->last() / before->last();
     // We exempt parallel collection from this check because Alloc Buffer
     // fragmentation can produce negative collections.
     // Further, we're now always doing parallel collection.  But I'm still
     // leaving this here as a placeholder for a more precise assertion later.
     // (DLD, 10/05.)
     assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
            last_survival_rate <= 1.0, "Or bad frac");
     return last_survival_rate;
   } else {
     return 1.0;
   }
 }
 static const int survival_min_obs = 5;
 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
 static const double min_survival_rate = 0.1;
 double
 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
                                                            double latest) {
   double res = avg;
   if (number_of_recent_gcs() < survival_min_obs) {
     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
   }
   res = MAX2(res, latest);
   res = MAX2(res, min_survival_rate);
   // In the parallel case, LAB fragmentation can produce "negative
   // collections"; so can evac failure.  Cap at 1.0
   res = MIN2(res, 1.0);
   return res;
 }
 size_t G1CollectorPolicy::expansion_amount() {
   if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
     // 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);
     if (G1PolicyVerbose > 1) {
       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
                  "                   Answer = %d.\n",
                  recent_avg_pause_time_ratio(),
                  byte_size_in_proper_unit(committed_bytes),
                  proper_unit_for_byte_size(committed_bytes),
                  byte_size_in_proper_unit(uncommitted_bytes),
                  proper_unit_for_byte_size(uncommitted_bytes),
                  byte_size_in_proper_unit(expand_bytes_via_pct),
                  proper_unit_for_byte_size(expand_bytes_via_pct),
                  byte_size_in_proper_unit(expand_bytes),
                  proper_unit_for_byte_size(expand_bytes));
     }
     return expand_bytes;
   } else {
     return 0;
   }
 }
 void G1CollectorPolicy::note_start_of_mark_thread() {
   _mark_thread_startup_sec = os::elapsedTime();
 }
 class CountCSClosure: public HeapRegionClosure {
   G1CollectorPolicy* _g1_policy;
 public:
   CountCSClosure(G1CollectorPolicy* g1_policy) :
     _g1_policy(g1_policy) {}
   bool doHeapRegion(HeapRegion* r) {
     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
     return false;
   }
 };
 void G1CollectorPolicy::count_CS_bytes_used() {
   CountCSClosure cs_closure(this);
   _g1->collection_set_iterate(&cs_closure);
 }
 static void print_indent(int level) {
   for (int j = 0; j < level+1; ++j)
     gclog_or_tty->print("   ");
 }
 void G1CollectorPolicy::print_summary (int level,
                                        const char* str,
                                        NumberSeq* seq) const {
   double sum = seq->sum();
   print_indent(level);
   gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
                 str, sum / 1000.0, seq->avg());
 }
 void G1CollectorPolicy::print_summary_sd (int level,
                                           const char* str,
                                           NumberSeq* seq) const {
   print_summary(level, str, seq);
   print_indent(level + 5);
   gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
                 seq->num(), seq->sd(), seq->maximum());
 }
 void G1CollectorPolicy::check_other_times(int level,
                                         NumberSeq* other_times_ms,
                                         NumberSeq* calc_other_times_ms) const {
   bool should_print = false;
   double max_sum = MAX2(fabs(other_times_ms->sum()),
                         fabs(calc_other_times_ms->sum()));
   double min_sum = MIN2(fabs(other_times_ms->sum()),
                         fabs(calc_other_times_ms->sum()));
   double sum_ratio = max_sum / min_sum;
   if (sum_ratio > 1.1) {
     should_print = true;
     print_indent(level + 1);
     gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
   }
   double max_avg = MAX2(fabs(other_times_ms->avg()),
                         fabs(calc_other_times_ms->avg()));
   double min_avg = MIN2(fabs(other_times_ms->avg()),
                         fabs(calc_other_times_ms->avg()));
   double avg_ratio = max_avg / min_avg;
   if (avg_ratio > 1.1) {
     should_print = true;
     print_indent(level + 1);
     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
   }
   if (other_times_ms->sum() < -0.01) {
     print_indent(level + 1);
     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
   }
   if (other_times_ms->avg() < -0.01) {
     print_indent(level + 1);
     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
   }
   if (calc_other_times_ms->sum() < -0.01) {
     should_print = true;
     print_indent(level + 1);
     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
   }
   if (calc_other_times_ms->avg() < -0.01) {
     should_print = true;
     print_indent(level + 1);
     gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
   }
   if (should_print)
     print_summary(level, "Other(Calc)", calc_other_times_ms);
 }
 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
   bool parallel = G1CollectedHeap::use_parallel_gc_threads();
   MainBodySummary*    body_summary = summary->main_body_summary();
   if (summary->get_total_seq()->num() > 0) {
     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
     if (body_summary != NULL) {
       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
       if (parallel) {
         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
         print_summary(2, "Ext Root Scanning",
                       body_summary->get_ext_root_scan_seq());
         print_summary(2, "Mark Stack Scanning",
                       body_summary->get_mark_stack_scan_seq());
         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
         print_summary(2, "Termination", body_summary->get_termination_seq());
         print_summary(2, "Other", body_summary->get_parallel_other_seq());
         {
           NumberSeq* other_parts[] = {
             body_summary->get_update_rs_seq(),
             body_summary->get_ext_root_scan_seq(),
             body_summary->get_mark_stack_scan_seq(),
             body_summary->get_scan_rs_seq(),
             body_summary->get_obj_copy_seq(),
             body_summary->get_termination_seq()
           };
           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
 , other_parts);
           check_other_times(2, body_summary->get_parallel_other_seq(),
                             &calc_other_times_ms);
         }
         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
       } else {
         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
         print_summary(1, "Ext Root Scanning",
                       body_summary->get_ext_root_scan_seq());
         print_summary(1, "Mark Stack Scanning",
                       body_summary->get_mark_stack_scan_seq());
         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
       }
     }
     print_summary(1, "Other", summary->get_other_seq());
     {
       if (body_summary != NULL) {
         NumberSeq calc_other_times_ms;
         if (parallel) {
           // parallel
           NumberSeq* other_parts[] = {
             body_summary->get_satb_drain_seq(),
             body_summary->get_parallel_seq(),
             body_summary->get_clear_ct_seq()
           };
           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
 , other_parts);
         } else {
           // serial
           NumberSeq* other_parts[] = {
             body_summary->get_satb_drain_seq(),
             body_summary->get_update_rs_seq(),
             body_summary->get_ext_root_scan_seq(),
             body_summary->get_mark_stack_scan_seq(),
             body_summary->get_scan_rs_seq(),
             body_summary->get_obj_copy_seq()
           };
           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
 , other_parts);
         }
         check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
       }
     }
   } else {
     print_indent(0);
     gclog_or_tty->print_cr("none");
   }
   gclog_or_tty->print_cr("");
 }
 void G1CollectorPolicy::print_tracing_info() const {
   if (TraceGen0Time) {
     gclog_or_tty->print_cr("ALL PAUSES");
     print_summary_sd(0, "Total", _all_pause_times_ms);
     gclog_or_tty->print_cr("");
     gclog_or_tty->print_cr("");
     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
     gclog_or_tty->print_cr("");
     gclog_or_tty->print_cr("EVACUATION PAUSES");
     print_summary(_summary);
     gclog_or_tty->print_cr("MISC");
     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
     print_summary_sd(0, "Yields", _all_yield_times_ms);
     for (int i = 0; i < _aux_num; ++i) {
       if (_all_aux_times_ms[i].num() > 0) {
         char buffer[96];
         sprintf(buffer, "Aux%d", i);
         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
       }
     }
     size_t all_region_num = _region_num_young + _region_num_tenured;
     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
                "Tenured %8d (%6.2lf%%)",
                all_region_num,
                _region_num_young,
                (double) _region_num_young / (double) all_region_num * 100.0,
                _region_num_tenured,
                (double) _region_num_tenured / (double) all_region_num * 100.0);
   }
   if (TraceGen1Time) {
     if (_all_full_gc_times_ms->num() > 0) {
       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
                  _all_full_gc_times_ms->num(),
                  _all_full_gc_times_ms->sum() / 1000.0);
       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
                     _all_full_gc_times_ms->sd(),
                     _all_full_gc_times_ms->maximum());
     }
   }
 }
 void G1CollectorPolicy::print_yg_surv_rate_info() const {
 #ifndef PRODUCT
   _short_lived_surv_rate_group->print_surv_rate_summary();
   // add this call for any other surv rate groups
 #endif // PRODUCT
 }
 void
 G1CollectorPolicy::update_region_num(bool young) {
   if (young) {
     ++_region_num_young;
   } else {
     ++_region_num_tenured;
   }
 }
 #ifndef PRODUCT
 // for debugging, bit of a hack...
 static char*
 region_num_to_mbs(int length) {
   static char buffer[64];
   double bytes = (double) (length * HeapRegion::GrainBytes);
   double mbs = bytes / (double) (1024 * 1024);
   sprintf(buffer, "%7.2lfMB", mbs);
   return buffer;
 }
 #endif // PRODUCT
 size_t G1CollectorPolicy::max_regions(int purpose) {
   switch (purpose) {
     case GCAllocForSurvived:
       return _max_survivor_regions;
     case GCAllocForTenured:
       return REGIONS_UNLIMITED;
     default:
       ShouldNotReachHere();
       return REGIONS_UNLIMITED;
   };
 }
 void G1CollectorPolicy::calculate_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::calculate_survivors_policy()
 {
   if (G1FixedSurvivorSpaceSize == 0) {
     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
   } else {
     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   }
   if (G1FixedTenuringThreshold) {
     _tenuring_threshold = MaxTenuringThreshold;
   } else {
     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
         HeapRegion::GrainWords * _max_survivor_regions);
   }
 }
 #ifndef PRODUCT
 class HRSortIndexIsOKClosure: public HeapRegionClosure {
   CollectionSetChooser* _chooser;
 public:
   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
     _chooser(chooser) {}
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
     }
     return false;
   }
 };
 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
   HRSortIndexIsOKClosure cl(_collectionSetChooser);
   _g1->heap_region_iterate(&cl);
   return true;
 }
 #endif
 bool
 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
   if (!during_cycle) {
     set_initiate_conc_mark_if_possible();
     return true;
   } else {
     return false;
   }
 }
 void
 G1CollectorPolicy::decide_on_conc_mark_initiation() {
   // We are about to decide on whether this pause will be an
   // initial-mark pause.
   // First, during_initial_mark_pause() should not be already set. We
   // will set it here if we have to. However, it should be cleared by
   // the end of the pause (it's only set for the duration of an
   // initial-mark pause).
   assert(!during_initial_mark_pause(), "pre-condition");
   if (initiate_conc_mark_if_possible()) {
     // We had noticed on a previous pause that the heap occupancy has
     // gone over the initiating threshold and we should start a
     // concurrent marking cycle. So we might initiate one.
     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
     if (!during_cycle) {
       // The concurrent marking thread is not "during a cycle", i.e.,
       // it has completed the last one. So we can go ahead and
       // initiate a new cycle.
       set_during_initial_mark_pause();
       // And we can now clear initiate_conc_mark_if_possible() as
       // we've already acted on it.
       clear_initiate_conc_mark_if_possible();
     } 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.
     }
   }
 }
 void
 G1CollectorPolicy_BestRegionsFirst::
 record_collection_pause_start(double start_time_sec, size_t start_used) {
   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
 }
 class NextNonCSElemFinder: public HeapRegionClosure {
   HeapRegion* _res;
 public:
   NextNonCSElemFinder(): _res(NULL) {}
   bool doHeapRegion(HeapRegion* r) {
     if (!r->in_collection_set()) {
       _res = r;
       return true;
     } else {
       return false;
     }
   }
   HeapRegion* res() { return _res; }
 };
 class KnownGarbageClosure: public HeapRegionClosure {
   CollectionSetChooser* _hrSorted;
 public:
   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
     _hrSorted(hrSorted)
   {}
   bool doHeapRegion(HeapRegion* r) {
     // We only include humongous regions in collection
     // sets when concurrent mark shows that their contained object is
     // unreachable.
     // Do we have any marking information for this region?
     if (r->is_marked()) {
       // We don't include humongous regions in collection
       // sets because we collect them immediately at the end of a marking
       // cycle.  We also don't include young regions because we *must*
       // include them in the next collection pause.
       if (!r->isHumongous() && !r->is_young()) {
         _hrSorted->addMarkedHeapRegion(r);
       }
     }
     return false;
   }
 };
 class ParKnownGarbageHRClosure: public HeapRegionClosure {
   CollectionSetChooser* _hrSorted;
   jint _marked_regions_added;
   jint _chunk_size;
   jint _cur_chunk_idx;
   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
   int _worker;
   int _invokes;
   void get_new_chunk() {
     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
   }
   void add_region(HeapRegion* r) {
     if (_cur_chunk_idx == _cur_chunk_end) {
       get_new_chunk();
     }
     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
     _marked_regions_added++;
     _cur_chunk_idx++;
   }
 public:
   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
                            jint chunk_size,
                            int worker) :
     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
     _invokes(0)
   {}
   bool doHeapRegion(HeapRegion* r) {
     // We only include humongous regions in collection
     // sets when concurrent mark shows that their contained object is
     // unreachable.
     _invokes++;
     // Do we have any marking information for this region?
     if (r->is_marked()) {
       // We don't include humongous regions in collection
       // sets because we collect them immediately at the end of a marking
       // cycle.
       // We also do not include young regions in collection sets
       if (!r->isHumongous() && !r->is_young()) {
         add_region(r);
       }
     }
     return false;
   }
   jint marked_regions_added() { return _marked_regions_added; }
   int invokes() { return _invokes; }
 };
 class ParKnownGarbageTask: public AbstractGangTask {
   CollectionSetChooser* _hrSorted;
   jint _chunk_size;
   G1CollectedHeap* _g1;
 public:
   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
     AbstractGangTask("ParKnownGarbageTask"),
     _hrSorted(hrSorted), _chunk_size(chunk_size),
     _g1(G1CollectedHeap::heap())
   {}
   void work(int i) {
     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
     // Back to zero for the claim value.
     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
                                          HeapRegion::InitialClaimValue);
     jint regions_added = parKnownGarbageCl.marked_regions_added();
     _hrSorted->incNumMarkedHeapRegions(regions_added);
     if (G1PrintParCleanupStats) {
       gclog_or_tty->print("     Thread %d called %d times, added %d regions to list.\n",
                  i, parKnownGarbageCl.invokes(), regions_added);
     }
   }
 };
 void
 G1CollectorPolicy_BestRegionsFirst::
 record_concurrent_mark_cleanup_end(size_t freed_bytes,
                                    size_t max_live_bytes) {
   double start;
   if (G1PrintParCleanupStats) start = os::elapsedTime();
   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
   _collectionSetChooser->clearMarkedHeapRegions();
   double clear_marked_end;
   if (G1PrintParCleanupStats) {
     clear_marked_end = os::elapsedTime();
     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
                   (clear_marked_end - start)*1000.0);
   }
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     const size_t OverpartitionFactor = 4;
     const size_t MinWorkUnit = 8;
     const size_t WorkUnit =
       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
            MinWorkUnit);
     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
                                                              WorkUnit);
     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
                                             (int) WorkUnit);
     _g1->workers()->run_task(&parKnownGarbageTask);
     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
            "sanity check");
   } else {
     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
     _g1->heap_region_iterate(&knownGarbagecl);
   }
   double known_garbage_end;
   if (G1PrintParCleanupStats) {
     known_garbage_end = os::elapsedTime();
     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
                   (known_garbage_end - clear_marked_end)*1000.0);
   }
   _collectionSetChooser->sortMarkedHeapRegions();
   double sort_end;
   if (G1PrintParCleanupStats) {
     sort_end = os::elapsedTime();
     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
                   (sort_end - known_garbage_end)*1000.0);
   }
   record_concurrent_mark_cleanup_end_work2();
   double work2_end;
   if (G1PrintParCleanupStats) {
     work2_end = os::elapsedTime();
     gclog_or_tty->print_cr("  work2: %8.3f ms.",
                   (work2_end - sort_end)*1000.0);
   }
 }
 // Add the heap region at the head of the non-incremental collection set
 void G1CollectorPolicy::
 add_to_collection_set(HeapRegion* hr) {
   assert(_inc_cset_build_state == Active, "Precondition");
   assert(!hr->is_young(), "non-incremental add of young region");
   if (G1PrintHeapRegions) {
     gclog_or_tty->print_cr("added region to cset "
                            "%d:["PTR_FORMAT", "PTR_FORMAT"], "
                            "top "PTR_FORMAT", %s",
                            hr->hrs_index(), hr->bottom(), hr->end(),
                            hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
   }
   if (_g1->mark_in_progress())
     _g1->concurrent_mark()->registerCSetRegion(hr);
   assert(!hr->in_collection_set(), "should not already be in the CSet");
   hr->set_in_collection_set(true);
   hr->set_next_in_collection_set(_collection_set);
   _collection_set = hr;
   _collection_set_size++;
   _collection_set_bytes_used_before += hr->used();
   _g1->register_region_with_in_cset_fast_test(hr);
 }
 // Initialize the per-collection-set information
 void G1CollectorPolicy::start_incremental_cset_building() {
   assert(_inc_cset_build_state == Inactive, "Precondition");
   _inc_cset_head = NULL;
   _inc_cset_tail = NULL;
   _inc_cset_size = 0;
   _inc_cset_bytes_used_before = 0;
   if (in_young_gc_mode()) {
     _inc_cset_young_index = 0;
   }
   _inc_cset_max_finger = 0;
   _inc_cset_recorded_young_bytes = 0;
   _inc_cset_recorded_rs_lengths = 0;
   _inc_cset_predicted_elapsed_time_ms = 0;
   _inc_cset_predicted_bytes_to_copy = 0;
   _inc_cset_build_state = Active;
 }
 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
   // This routine is used when:
   // * adding survivor regions to the incremental cset at the end of an
   //   evacuation pause,
   // * adding the current allocation region to the incremental cset
   //   when it is retired, and
   // * updating existing policy information for a region in the
   //   incremental cset via young list RSet sampling.
   // Therefore this routine may be called at a safepoint by the
   // VM thread, or in-between safepoints by mutator threads (when
   // retiring the current allocation region) or a concurrent
   // refine thread (RSet sampling).
   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
   size_t used_bytes = hr->used();
   _inc_cset_recorded_rs_lengths += rs_length;
   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
   _inc_cset_bytes_used_before += used_bytes;
   // Cache the values we have added to the aggregated informtion
   // in the heap region in case we have to remove this region from
   // the incremental collection set, or it is updated by the
   // rset sampling code
   hr->set_recorded_rs_length(rs_length);
   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
 #if PREDICTIONS_VERBOSE
   size_t bytes_to_copy = predict_bytes_to_copy(hr);
   _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
   // Record the number of bytes used in this region
   _inc_cset_recorded_young_bytes += used_bytes;
   // Cache the values we have added to the aggregated informtion
   // in the heap region in case we have to remove this region from
   // the incremental collection set, or it is updated by the
   // rset sampling code
   hr->set_predicted_bytes_to_copy(bytes_to_copy);
 #endif // PREDICTIONS_VERBOSE
 }
 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
   // This routine is currently only called as part of the updating of
   // existing policy information for regions in the incremental cset that
   // is performed by the concurrent refine thread(s) as part of young list
   // RSet sampling. Therefore we should not be at a safepoint.
   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
   assert(hr->is_young(), "it should be");
   size_t used_bytes = hr->used();
   size_t old_rs_length = hr->recorded_rs_length();
   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
   // Subtract the old recorded/predicted policy information for
   // the given heap region from the collection set info.
   _inc_cset_recorded_rs_lengths -= old_rs_length;
   _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
   _inc_cset_bytes_used_before -= used_bytes;
   // Clear the values cached in the heap region
   hr->set_recorded_rs_length(0);
   hr->set_predicted_elapsed_time_ms(0);
 #if PREDICTIONS_VERBOSE
   size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
   _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
   // Subtract the number of bytes used in this region
   _inc_cset_recorded_young_bytes -= used_bytes;
   // Clear the values cached in the heap region
   hr->set_predicted_bytes_to_copy(0);
 #endif // PREDICTIONS_VERBOSE
 }
 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
   // Update the collection set information that is dependent on the new RS length
   assert(hr->is_young(), "Precondition");
   remove_from_incremental_cset_info(hr);
   add_to_incremental_cset_info(hr, new_rs_length);
 }
 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
   assert( hr->is_young(), "invariant");
   assert( hr->young_index_in_cset() == -1, "invariant" );
   assert(_inc_cset_build_state == Active, "Precondition");
   // We need to clear and set the cached recorded/cached collection set
   // information in the heap region here (before the region gets added
   // to the collection set). An individual heap region's cached values
   // are calculated, aggregated with the policy collection set info,
   // and cached in the heap region here (initially) and (subsequently)
   // by the Young List sampling code.
   size_t rs_length = hr->rem_set()->occupied();
   add_to_incremental_cset_info(hr, rs_length);
   HeapWord* hr_end = hr->end();
   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
   assert(!hr->in_collection_set(), "invariant");
   hr->set_in_collection_set(true);
   assert( hr->next_in_collection_set() == NULL, "invariant");
   _inc_cset_size++;
   _g1->register_region_with_in_cset_fast_test(hr);
   hr->set_young_index_in_cset((int) _inc_cset_young_index);
   ++_inc_cset_young_index;
 }
 // Add the region at the RHS of the incremental cset
 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
   // We should only ever be appending survivors at the end of a pause
   assert( hr->is_survivor(), "Logic");
   // Do the 'common' stuff
   add_region_to_incremental_cset_common(hr);
   // Now add the region at the right hand side
   if (_inc_cset_tail == NULL) {
     assert(_inc_cset_head == NULL, "invariant");
     _inc_cset_head = hr;
   } else {
     _inc_cset_tail->set_next_in_collection_set(hr);
   }
   _inc_cset_tail = hr;
   if (G1PrintHeapRegions) {
     gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
                   "%d:["PTR_FORMAT", "PTR_FORMAT"], "
                   "top "PTR_FORMAT", young %s",
                   hr->hrs_index(), hr->bottom(), hr->end(),
                   hr->top(), (hr->is_young()) ? "YES" : "NO");
   }
 }
 // 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;
   if (G1PrintHeapRegions) {
     gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
                   "%d:["PTR_FORMAT", "PTR_FORMAT"], "
                   "top "PTR_FORMAT", young %s",
                   hr->hrs_index(), hr->bottom(), hr->end(),
                   hr->top(), (hr->is_young()) ? "YES" : "NO");
   }
 }
 #ifndef PRODUCT
 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
   st->print_cr("\nCollection_set:");
   HeapRegion* csr = list_head;
   while (csr != NULL) {
     HeapRegion* next = csr->next_in_collection_set();
     assert(csr->in_collection_set(), "bad CS");
     st->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
                  "age: %4d, y: %d, surv: %d",
                         csr->bottom(), csr->end(),
                         csr->top(),
                         csr->prev_top_at_mark_start(),
                         csr->next_top_at_mark_start(),
                         csr->top_at_conc_mark_count(),
                         csr->age_in_surv_rate_group_cond(),
                         csr->is_young(),
                         csr->is_survivor());
     csr = next;
   }
 }
 #endif // !PRODUCT
 void
 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
                                                   double target_pause_time_ms) {
   // Set this here - in case we're not doing young collections.
   double non_young_start_time_sec = os::elapsedTime();
   start_recording_regions();
   guarantee(target_pause_time_ms > 0.0,
             err_msg("target_pause_time_ms = %1.6lf should be positive",
                     target_pause_time_ms));
   guarantee(_collection_set == NULL, "Precondition");
   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
   double predicted_pause_time_ms = base_time_ms;
   double time_remaining_ms = target_pause_time_ms - base_time_ms;
   // the 10% and 50% values are arbitrary...
   if (time_remaining_ms < 0.10 * target_pause_time_ms) {
     time_remaining_ms = 0.50 * target_pause_time_ms;
     _within_target = false;
   } else {
     _within_target = true;
   }
   // We figure out the number of bytes available for future to-space.
   // For new regions without marking information, we must assume the
   // worst-case of complete survival.  If we have marking information for a
   // region, we can bound the amount of live data.  We can add a number of
   // such regions, as long as the sum of the live data bounds does not
   // exceed the available evacuation space.
   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
   size_t expansion_bytes =
     _g1->expansion_regions() * HeapRegion::GrainBytes;
   _collection_set_bytes_used_before = 0;
   _collection_set_size = 0;
   // Adjust for expansion and slop.
   max_live_bytes = max_live_bytes + expansion_bytes;
   HeapRegion* hr;
   if (in_young_gc_mode()) {
     double young_start_time_sec = os::elapsedTime();
     if (G1PolicyVerbose > 0) {
       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
                     _g1->young_list()->length());
     }
     _young_cset_length  = 0;
     _last_young_gc_full = full_young_gcs() ? true : false;
     if (_last_young_gc_full)
       ++_full_young_pause_num;
     else
       ++_partial_young_pause_num;
     // The young list is laid with the survivor regions from the previous
     // pause are appended to the RHS of the young list, i.e.
     //   [Newly Young Regions ++ Survivors from last pause].
     hr = _g1->young_list()->first_survivor_region();
     while (hr != NULL) {
       assert(hr->is_survivor(), "badly formed young list");
       hr->set_young();
       hr = hr->get_next_young_region();
     }
     // Clear the fields that point to the survivor list - they are
     // all young now.
     _g1->young_list()->clear_survivors();
     if (_g1->mark_in_progress())
       _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
     _young_cset_length = _inc_cset_young_index;
     _collection_set = _inc_cset_head;
     _collection_set_size = _inc_cset_size;
     _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
     // For young regions in the collection set, we assume the worst
     // case of complete survival
     max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
     time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
     predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
     // The number of recorded young regions is the incremental
     // collection set's current size
     set_recorded_young_regions(_inc_cset_size);
     set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
     set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
 #if PREDICTIONS_VERBOSE
     set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
 #endif // PREDICTIONS_VERBOSE
     if (G1PolicyVerbose > 0) {
       gclog_or_tty->print_cr("  Added " PTR_FORMAT " Young Regions to CS.",
                              _inc_cset_size);
       gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
                             max_live_bytes/K);
     }
     assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
     double young_end_time_sec = os::elapsedTime();
     _recorded_young_cset_choice_time_ms =
       (young_end_time_sec - young_start_time_sec) * 1000.0;
     // We are doing young collections so reset this.
     non_young_start_time_sec = young_end_time_sec;
     // Note we can use either _collection_set_size or
     // _young_cset_length here
     if (_collection_set_size > 0 && _last_young_gc_full) {
       // don't bother adding more regions...
       goto choose_collection_set_end;
     }
   }
   if (!in_young_gc_mode() || !full_young_gcs()) {
     bool should_continue = true;
     NumberSeq seq;
     double avg_prediction = 100000000000000000.0; // something very large
     do {
       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
                                                       avg_prediction);
       if (hr != NULL) {
         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
         time_remaining_ms -= predicted_time_ms;
         predicted_pause_time_ms += predicted_time_ms;
         add_to_collection_set(hr);
         record_non_young_cset_region(hr);
         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
         if (G1PolicyVerbose > 0) {
           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
                         max_live_bytes/K);
         }
         seq.add(predicted_time_ms);
         avg_prediction = seq.avg() + seq.sd();
       }
       should_continue =
         ( hr != NULL) &&
         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
           : _collection_set_size < _young_list_fixed_length );
     } while (should_continue);
     if (!adaptive_young_list_length() &&
         _collection_set_size < _young_list_fixed_length)
       _should_revert_to_full_young_gcs  = true;
   }
 choose_collection_set_end:
   stop_incremental_cset_building();
   count_CS_bytes_used();
   end_recording_regions();
   double non_young_end_time_sec = os::elapsedTime();
   _recorded_non_young_cset_choice_time_ms =
     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
 }
 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
   G1CollectorPolicy::record_full_collection_end();
   _collectionSetChooser->updateAfterFullCollection();
 }
 void G1CollectorPolicy_BestRegionsFirst::
 expand_if_possible(size_t numRegions) {
   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
   _g1->expand(expansion_bytes);
 }
 void G1CollectorPolicy_BestRegionsFirst::
 record_collection_pause_end() {
   G1CollectorPolicy::record_collection_pause_end();
   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp@c33825b68624 (annotated)

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